Mercurial > hg > truffle
diff src/share/vm/prims/jvmtiTagMap.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/prims/jvmtiTagMap.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,3535 @@ +/* + * Copyright 2003-2007 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +# include "incls/_precompiled.incl" +# include "incls/_jvmtiTagMap.cpp.incl" + +// JvmtiTagHashmapEntry +// +// Each entry encapsulates a JNI weak reference to the tagged object +// and the tag value. In addition an entry includes a next pointer which +// is used to chain entries together. + +class JvmtiTagHashmapEntry : public CHeapObj { + private: + friend class JvmtiTagMap; + + jweak _object; // JNI weak ref to tagged object + jlong _tag; // the tag + JvmtiTagHashmapEntry* _next; // next on the list + + inline void init(jweak object, jlong tag) { + _object = object; + _tag = tag; + _next = NULL; + } + + // constructor + JvmtiTagHashmapEntry(jweak object, jlong tag) { init(object, tag); } + + public: + + // accessor methods + inline jweak object() const { return _object; } + inline jlong tag() const { return _tag; } + + inline void set_tag(jlong tag) { + assert(tag != 0, "can't be zero"); + _tag = tag; + } + + inline JvmtiTagHashmapEntry* next() const { return _next; } + inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; } +}; + + +// JvmtiTagHashmap +// +// A hashmap is essentially a table of pointers to entries. Entries +// are hashed to a location, or position in the table, and then +// chained from that location. The "key" for hashing is address of +// the object, or oop. The "value" is the JNI weak reference to the +// object and the tag value. Keys are not stored with the entry. +// Instead the weak reference is resolved to obtain the key. +// +// A hashmap maintains a count of the number entries in the hashmap +// and resizes if the number of entries exceeds a given threshold. +// The threshold is specified as a percentage of the size - for +// example a threshold of 0.75 will trigger the hashmap to resize +// if the number of entries is >75% of table size. +// +// A hashmap provides functions for adding, removing, and finding +// entries. It also provides a function to iterate over all entries +// in the hashmap. + +class JvmtiTagHashmap : public CHeapObj { + private: + friend class JvmtiTagMap; + + enum { + small_trace_threshold = 10000, // threshold for tracing + medium_trace_threshold = 100000, + large_trace_threshold = 1000000, + initial_trace_threshold = small_trace_threshold + }; + + static int _sizes[]; // array of possible hashmap sizes + int _size; // actual size of the table + int _size_index; // index into size table + + int _entry_count; // number of entries in the hashmap + + float _load_factor; // load factor as a % of the size + int _resize_threshold; // computed threshold to trigger resizing. + bool _resizing_enabled; // indicates if hashmap can resize + + int _trace_threshold; // threshold for trace messages + + JvmtiTagHashmapEntry** _table; // the table of entries. + + // private accessors + int resize_threshold() const { return _resize_threshold; } + int trace_threshold() const { return _trace_threshold; } + + // initialize the hashmap + void init(int size_index=0, float load_factor=4.0f) { + int initial_size = _sizes[size_index]; + _size_index = size_index; + _size = initial_size; + _entry_count = 0; + if (TraceJVMTIObjectTagging) { + _trace_threshold = initial_trace_threshold; + } else { + _trace_threshold = -1; + } + _load_factor = load_factor; + _resize_threshold = (int)(_load_factor * _size); + _resizing_enabled = true; + size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*); + _table = (JvmtiTagHashmapEntry**)os::malloc(s); + if (_table == NULL) { + vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags"); + } + for (int i=0; i<initial_size; i++) { + _table[i] = NULL; + } + } + + // hash a given key (oop) with the specified size + static unsigned int hash(oop key, int size) { + // shift right to get better distribution (as these bits will be zero + // with aligned addresses) + unsigned int addr = (unsigned int)((intptr_t)key); +#ifdef _LP64 + return (addr >> 3) % size; +#else + return (addr >> 2) % size; +#endif + } + + // hash a given key (oop) + unsigned int hash(oop key) { + return hash(key, _size); + } + + // resize the hashmap - allocates a large table and re-hashes + // all entries into the new table. + void resize() { + int new_size_index = _size_index+1; + int new_size = _sizes[new_size_index]; + if (new_size < 0) { + // hashmap already at maximum capacity + return; + } + + // allocate new table + size_t s = new_size * sizeof(JvmtiTagHashmapEntry*); + JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s); + if (new_table == NULL) { + warning("unable to allocate larger hashtable for jvmti object tags"); + set_resizing_enabled(false); + return; + } + + // initialize new table + int i; + for (i=0; i<new_size; i++) { + new_table[i] = NULL; + } + + // rehash all entries into the new table + for (i=0; i<_size; i++) { + JvmtiTagHashmapEntry* entry = _table[i]; + while (entry != NULL) { + JvmtiTagHashmapEntry* next = entry->next(); + oop key = JNIHandles::resolve(entry->object()); + assert(key != NULL, "jni weak reference cleared!!"); + unsigned int h = hash(key, new_size); + JvmtiTagHashmapEntry* anchor = new_table[h]; + if (anchor == NULL) { + new_table[h] = entry; + entry->set_next(NULL); + } else { + entry->set_next(anchor); + new_table[h] = entry; + } + entry = next; + } + } + + // free old table and update settings. + os::free((void*)_table); + _table = new_table; + _size_index = new_size_index; + _size = new_size; + + // compute new resize threshold + _resize_threshold = (int)(_load_factor * _size); + } + + + // internal remove function - remove an entry at a given position in the + // table. + inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) { + assert(pos >= 0 && pos < _size, "out of range"); + if (prev == NULL) { + _table[pos] = entry->next(); + } else { + prev->set_next(entry->next()); + } + assert(_entry_count > 0, "checking"); + _entry_count--; + } + + // resizing switch + bool is_resizing_enabled() const { return _resizing_enabled; } + void set_resizing_enabled(bool enable) { _resizing_enabled = enable; } + + // debugging + void print_memory_usage(); + void compute_next_trace_threshold(); + + public: + + // create a JvmtiTagHashmap of a preferred size and optionally a load factor. + // The preferred size is rounded down to an actual size. + JvmtiTagHashmap(int size, float load_factor=0.0f) { + int i=0; + while (_sizes[i] < size) { + if (_sizes[i] < 0) { + assert(i > 0, "sanity check"); + i--; + break; + } + i++; + } + + // if a load factor is specified then use it, otherwise use default + if (load_factor > 0.01f) { + init(i, load_factor); + } else { + init(i); + } + } + + // create a JvmtiTagHashmap with default settings + JvmtiTagHashmap() { + init(); + } + + // release table when JvmtiTagHashmap destroyed + ~JvmtiTagHashmap() { + if (_table != NULL) { + os::free((void*)_table); + _table = NULL; + } + } + + // accessors + int size() const { return _size; } + JvmtiTagHashmapEntry** table() const { return _table; } + int entry_count() const { return _entry_count; } + + // find an entry in the hashmap, returns NULL if not found. + inline JvmtiTagHashmapEntry* find(oop key) { + unsigned int h = hash(key); + JvmtiTagHashmapEntry* entry = _table[h]; + while (entry != NULL) { + oop orig_key = JNIHandles::resolve(entry->object()); + assert(orig_key != NULL, "jni weak reference cleared!!"); + if (key == orig_key) { + break; + } + entry = entry->next(); + } + return entry; + } + + + // add a new entry to hashmap + inline void add(oop key, JvmtiTagHashmapEntry* entry) { + assert(key != NULL, "checking"); + assert(find(key) == NULL, "duplicate detected"); + unsigned int h = hash(key); + JvmtiTagHashmapEntry* anchor = _table[h]; + if (anchor == NULL) { + _table[h] = entry; + entry->set_next(NULL); + } else { + entry->set_next(anchor); + _table[h] = entry; + } + + _entry_count++; + if (trace_threshold() > 0 && entry_count() >= trace_threshold()) { + assert(TraceJVMTIObjectTagging, "should only get here when tracing"); + print_memory_usage(); + compute_next_trace_threshold(); + } + + // if the number of entries exceed the threshold then resize + if (entry_count() > resize_threshold() && is_resizing_enabled()) { + resize(); + } + } + + // remove an entry with the given key. + inline JvmtiTagHashmapEntry* remove(oop key) { + unsigned int h = hash(key); + JvmtiTagHashmapEntry* entry = _table[h]; + JvmtiTagHashmapEntry* prev = NULL; + while (entry != NULL) { + oop orig_key = JNIHandles::resolve(entry->object()); + assert(orig_key != NULL, "jni weak reference cleared!!"); + if (key == orig_key) { + break; + } + prev = entry; + entry = entry->next(); + } + if (entry != NULL) { + remove(prev, h, entry); + } + return entry; + } + + // iterate over all entries in the hashmap + void entry_iterate(JvmtiTagHashmapEntryClosure* closure); +}; + +// possible hashmap sizes - odd primes that roughly double in size. +// To avoid excessive resizing the odd primes from 4801-76831 and +// 76831-307261 have been removed. The list must be terminated by -1. +int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891, + 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 }; + + +// A supporting class for iterating over all entries in Hashmap +class JvmtiTagHashmapEntryClosure { + public: + virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0; +}; + + +// iterate over all entries in the hashmap +void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { + for (int i=0; i<_size; i++) { + JvmtiTagHashmapEntry* entry = _table[i]; + JvmtiTagHashmapEntry* prev = NULL; + while (entry != NULL) { + // obtain the next entry before invoking do_entry - this is + // necessary because do_entry may remove the entry from the + // hashmap. + JvmtiTagHashmapEntry* next = entry->next(); + closure->do_entry(entry); + entry = next; + } + } +} + +// debugging +void JvmtiTagHashmap::print_memory_usage() { + intptr_t p = (intptr_t)this; + tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p); + + // table + entries in KB + int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) + + entry_count()*sizeof(JvmtiTagHashmapEntry))/K; + + int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K); + tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]", + entry_count(), hashmap_usage, weak_globals_usage); +} + +// compute threshold for the next trace message +void JvmtiTagHashmap::compute_next_trace_threshold() { + if (trace_threshold() < medium_trace_threshold) { + _trace_threshold += small_trace_threshold; + } else { + if (trace_threshold() < large_trace_threshold) { + _trace_threshold += medium_trace_threshold; + } else { + _trace_threshold += large_trace_threshold; + } + } +} + +// memory region for young generation +MemRegion JvmtiTagMap::_young_gen; + +// get the memory region used for the young generation +void JvmtiTagMap::get_young_generation() { + if (Universe::heap()->kind() == CollectedHeap::GenCollectedHeap) { + GenCollectedHeap* gch = GenCollectedHeap::heap(); + _young_gen = gch->get_gen(0)->reserved(); + } else { +#ifndef SERIALGC + ParallelScavengeHeap* psh = ParallelScavengeHeap::heap(); + _young_gen= psh->young_gen()->reserved(); +#else // SERIALGC + fatal("SerialGC only supported in this configuration."); +#endif // SERIALGC + } +} + +// returns true if oop is in the young generation +inline bool JvmtiTagMap::is_in_young(oop o) { + assert(_young_gen.start() != NULL, "checking"); + void* p = (void*)o; + bool in_young = _young_gen.contains(p); + return in_young; +} + +// returns the appropriate hashmap for a given object +inline JvmtiTagHashmap* JvmtiTagMap::hashmap_for(oop o) { + if (is_in_young(o)) { + return _hashmap[0]; + } else { + return _hashmap[1]; + } +} + + +// create a JvmtiTagMap +JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) : + _env(env), + _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false), + _free_entries(NULL), + _free_entries_count(0) +{ + assert(JvmtiThreadState_lock->is_locked(), "sanity check"); + assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment"); + + // create the hashmaps + for (int i=0; i<n_hashmaps; i++) { + _hashmap[i] = new JvmtiTagHashmap(); + } + + // get the memory region used by the young generation + get_young_generation(); + + // finally add us to the environment + ((JvmtiEnvBase *)env)->set_tag_map(this); +} + + +// destroy a JvmtiTagMap +JvmtiTagMap::~JvmtiTagMap() { + + // no lock acquired as we assume the enclosing environment is + // also being destroryed. + ((JvmtiEnvBase *)_env)->set_tag_map(NULL); + + // iterate over the hashmaps and destroy each of the entries + for (int i=0; i<n_hashmaps; i++) { + JvmtiTagHashmap* hashmap = _hashmap[i]; + JvmtiTagHashmapEntry** table = hashmap->table(); + for (int j=0; j<hashmap->size(); j++) { + JvmtiTagHashmapEntry *entry = table[j]; + while (entry != NULL) { + JvmtiTagHashmapEntry* next = entry->next(); + jweak ref = entry->object(); + JNIHandles::destroy_weak_global(ref); + delete entry; + entry = next; + } + } + + // finally destroy the hashmap + delete hashmap; + } + + // remove any entries on the free list + JvmtiTagHashmapEntry* entry = _free_entries; + while (entry != NULL) { + JvmtiTagHashmapEntry* next = entry->next(); + delete entry; + entry = next; + } +} + +// create a hashmap entry +// - if there's an entry on the (per-environment) free list then this +// is returned. Otherwise an new entry is allocated. +JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) { + assert(Thread::current()->is_VM_thread() || is_locked(), "checking"); + JvmtiTagHashmapEntry* entry; + if (_free_entries == NULL) { + entry = new JvmtiTagHashmapEntry(ref, tag); + } else { + assert(_free_entries_count > 0, "mismatched _free_entries_count"); + _free_entries_count--; + entry = _free_entries; + _free_entries = entry->next(); + entry->init(ref, tag); + } + return entry; +} + +// destroy an entry by returning it to the free list +void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) { + assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); + // limit the size of the free list + if (_free_entries_count >= max_free_entries) { + delete entry; + } else { + entry->set_next(_free_entries); + _free_entries = entry; + _free_entries_count++; + } +} + +// returns the tag map for the given environments. If the tag map +// doesn't exist then it is created. +JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) { + JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map(); + if (tag_map == NULL) { + MutexLocker mu(JvmtiThreadState_lock); + tag_map = ((JvmtiEnvBase *)env)->tag_map(); + if (tag_map == NULL) { + tag_map = new JvmtiTagMap(env); + } + } else { + CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); + } + return tag_map; +} + +// iterate over all entries in the tag map. +void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { + for (int i=0; i<n_hashmaps; i++) { + JvmtiTagHashmap* hashmap = _hashmap[i]; + hashmap->entry_iterate(closure); + } +} + +// returns true if the hashmaps are empty +bool JvmtiTagMap::is_empty() { + assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); + assert(n_hashmaps == 2, "not implemented"); + return ((_hashmap[0]->entry_count() == 0) && (_hashmap[1]->entry_count() == 0)); +} + + +// Return the tag value for an object, or 0 if the object is +// not tagged +// +static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) { + JvmtiTagHashmapEntry* entry = tag_map->hashmap_for(o)->find(o); + if (entry == NULL) { + return 0; + } else { + return entry->tag(); + } +} + +// If the object is a java.lang.Class then return the klassOop, +// otherwise return the original object +static inline oop klassOop_if_java_lang_Class(oop o) { + if (o->klass() == SystemDictionary::class_klass()) { + if (!java_lang_Class::is_primitive(o)) { + o = (oop)java_lang_Class::as_klassOop(o); + assert(o != NULL, "class for non-primitive mirror must exist"); + } + } + return o; +} + +// A CallbackWrapper is a support class for querying and tagging an object +// around a callback to a profiler. The constructor does pre-callback +// work to get the tag value, klass tag value, ... and the destructor +// does the post-callback work of tagging or untagging the object. +// +// { +// CallbackWrapper wrapper(tag_map, o); +// +// (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...) +// +// } // wrapper goes out of scope here which results in the destructor +// checking to see if the object has been tagged, untagged, or the +// tag value has changed. +// +class CallbackWrapper : public StackObj { + private: + JvmtiTagMap* _tag_map; + JvmtiTagHashmap* _hashmap; + JvmtiTagHashmapEntry* _entry; + oop _o; + jlong _obj_size; + jlong _obj_tag; + klassOop _klass; // the object's class + jlong _klass_tag; + + protected: + JvmtiTagMap* tag_map() const { return _tag_map; } + + // invoked post-callback to tag, untag, or update the tag of an object + void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap, + JvmtiTagHashmapEntry* entry, jlong obj_tag); + public: + CallbackWrapper(JvmtiTagMap* tag_map, oop o) { + assert(Thread::current()->is_VM_thread() || tag_map->is_locked(), + "MT unsafe or must be VM thread"); + + // for Classes the klassOop is tagged + _o = klassOop_if_java_lang_Class(o); + + // object size + _obj_size = _o->size() * wordSize; + + // record the context + _tag_map = tag_map; + _hashmap = tag_map->hashmap_for(_o); + _entry = _hashmap->find(_o); + + // get object tag + _obj_tag = (_entry == NULL) ? 0 : _entry->tag(); + + // get the class and the class's tag value + if (_o == o) { + _klass = _o->klass(); + } else { + // if the object represents a runtime class then use the + // tag for java.lang.Class + _klass = SystemDictionary::class_klass(); + } + _klass_tag = tag_for(tag_map, _klass); + } + + ~CallbackWrapper() { + post_callback_tag_update(_o, _hashmap, _entry, _obj_tag); + } + + inline jlong* obj_tag_p() { return &_obj_tag; } + inline jlong obj_size() const { return _obj_size; } + inline jlong obj_tag() const { return _obj_tag; } + inline klassOop klass() const { return _klass; } + inline jlong klass_tag() const { return _klass_tag; } +}; + + + +// callback post-callback to tag, untag, or update the tag of an object +void inline CallbackWrapper::post_callback_tag_update(oop o, + JvmtiTagHashmap* hashmap, + JvmtiTagHashmapEntry* entry, + jlong obj_tag) { + if (entry == NULL) { + if (obj_tag != 0) { + // callback has tagged the object + assert(Thread::current()->is_VM_thread(), "must be VMThread"); + HandleMark hm; + Handle h(o); + jweak ref = JNIHandles::make_weak_global(h); + entry = tag_map()->create_entry(ref, obj_tag); + hashmap->add(o, entry); + } + } else { + // object was previously tagged - the callback may have untagged + // the object or changed the tag value + if (obj_tag == 0) { + jweak ref = entry->object(); + + JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o); + assert(entry_removed == entry, "checking"); + tag_map()->destroy_entry(entry); + + JNIHandles::destroy_weak_global(ref); + } else { + if (obj_tag != entry->tag()) { + entry->set_tag(obj_tag); + } + } + } +} + +// An extended CallbackWrapper used when reporting an object reference +// to the agent. +// +// { +// TwoOopCallbackWrapper wrapper(tag_map, referrer, o); +// +// (*callback)(wrapper.klass_tag(), +// wrapper.obj_size(), +// wrapper.obj_tag_p() +// wrapper.referrer_tag_p(), ...) +// +// } // wrapper goes out of scope here which results in the destructor +// checking to see if the referrer object has been tagged, untagged, +// or the tag value has changed. +// +class TwoOopCallbackWrapper : public CallbackWrapper { + private: + bool _is_reference_to_self; + JvmtiTagHashmap* _referrer_hashmap; + JvmtiTagHashmapEntry* _referrer_entry; + oop _referrer; + jlong _referrer_obj_tag; + jlong _referrer_klass_tag; + jlong* _referrer_tag_p; + + bool is_reference_to_self() const { return _is_reference_to_self; } + + public: + TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) : + CallbackWrapper(tag_map, o) + { + // self reference needs to be handled in a special way + _is_reference_to_self = (referrer == o); + + if (_is_reference_to_self) { + _referrer_klass_tag = klass_tag(); + _referrer_tag_p = obj_tag_p(); + } else { + // for Classes the klassOop is tagged + _referrer = klassOop_if_java_lang_Class(referrer); + // record the context + _referrer_hashmap = tag_map->hashmap_for(_referrer); + _referrer_entry = _referrer_hashmap->find(_referrer); + + // get object tag + _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag(); + _referrer_tag_p = &_referrer_obj_tag; + + // get referrer class tag. + klassOop k = (_referrer == referrer) ? // Check if referrer is a class... + _referrer->klass() // No, just get its class + : SystemDictionary::class_klass(); // Yes, its class is Class + _referrer_klass_tag = tag_for(tag_map, k); + } + } + + ~TwoOopCallbackWrapper() { + if (!is_reference_to_self()){ + post_callback_tag_update(_referrer, + _referrer_hashmap, + _referrer_entry, + _referrer_obj_tag); + } + } + + // address of referrer tag + // (for a self reference this will return the same thing as obj_tag_p()) + inline jlong* referrer_tag_p() { return _referrer_tag_p; } + + // referrer's class tag + inline jlong referrer_klass_tag() { return _referrer_klass_tag; } +}; + +// tag an object +// +// This function is performance critical. If many threads attempt to tag objects +// around the same time then it's possible that the Mutex associated with the +// tag map will be a hot lock. Eliminating this lock will not eliminate the issue +// because creating a JNI weak reference requires acquiring a global lock also. +void JvmtiTagMap::set_tag(jobject object, jlong tag) { + MutexLocker ml(lock()); + + // resolve the object + oop o = JNIHandles::resolve_non_null(object); + + // for Classes we tag the klassOop + o = klassOop_if_java_lang_Class(o); + + // see if the object is already tagged + JvmtiTagHashmap* hashmap = hashmap_for(o); + JvmtiTagHashmapEntry* entry = hashmap->find(o); + + // if the object is not already tagged then we tag it + if (entry == NULL) { + if (tag != 0) { + HandleMark hm; + Handle h(o); + jweak ref = JNIHandles::make_weak_global(h); + + // the object may have moved because make_weak_global may + // have blocked - thus it is necessary resolve the handle + // and re-hash the object. + o = h(); + entry = create_entry(ref, tag); + hashmap_for(o)->add(o, entry); + } else { + // no-op + } + } else { + // if the object is already tagged then we either update + // the tag (if a new tag value has been provided) + // or remove the object if the new tag value is 0. + // Removing the object requires that we also delete the JNI + // weak ref to the object. + if (tag == 0) { + jweak ref = entry->object(); + hashmap->remove(o); + destroy_entry(entry); + JNIHandles::destroy_weak_global(ref); + } else { + entry->set_tag(tag); + } + } +} + +// get the tag for an object +jlong JvmtiTagMap::get_tag(jobject object) { + MutexLocker ml(lock()); + + // resolve the object + oop o = JNIHandles::resolve_non_null(object); + + // for Classes get the tag from the klassOop + return tag_for(this, klassOop_if_java_lang_Class(o)); +} + + +// Helper class used to describe the static or instance fields of a class. +// For each field it holds the field index (as defined by the JVMTI specification), +// the field type, and the offset. + +class ClassFieldDescriptor: public CHeapObj { + private: + int _field_index; + int _field_offset; + char _field_type; + public: + ClassFieldDescriptor(int index, char type, int offset) : + _field_index(index), _field_type(type), _field_offset(offset) { + } + int field_index() const { return _field_index; } + char field_type() const { return _field_type; } + int field_offset() const { return _field_offset; } +}; + +class ClassFieldMap: public CHeapObj { + private: + enum { + initial_field_count = 5 + }; + + // list of field descriptors + GrowableArray<ClassFieldDescriptor*>* _fields; + + // constructor + ClassFieldMap(); + + // add a field + void add(int index, char type, int offset); + + // returns the field count for the given class + static int compute_field_count(instanceKlassHandle ikh); + + public: + ~ClassFieldMap(); + + // access + int field_count() { return _fields->length(); } + ClassFieldDescriptor* field_at(int i) { return _fields->at(i); } + + // functions to create maps of static or instance fields + static ClassFieldMap* create_map_of_static_fields(klassOop k); + static ClassFieldMap* create_map_of_instance_fields(oop obj); +}; + +ClassFieldMap::ClassFieldMap() { + _fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true); +} + +ClassFieldMap::~ClassFieldMap() { + for (int i=0; i<_fields->length(); i++) { + delete _fields->at(i); + } + delete _fields; +} + +void ClassFieldMap::add(int index, char type, int offset) { + ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset); + _fields->append(field); +} + +// Returns a heap allocated ClassFieldMap to describe the static fields +// of the given class. +// +ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) { + HandleMark hm; + instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k); + + // create the field map + ClassFieldMap* field_map = new ClassFieldMap(); + + FilteredFieldStream f(ikh, false, false); + int max_field_index = f.field_count()-1; + + int index = 0; + for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) { + // ignore instance fields + if (!fld.access_flags().is_static()) { + continue; + } + field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); + } + return field_map; +} + +// Returns a heap allocated ClassFieldMap to describe the instance fields +// of the given class. All instance fields are included (this means public +// and private fields declared in superclasses and superinterfaces too). +// +ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) { + HandleMark hm; + instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass()); + + // create the field map + ClassFieldMap* field_map = new ClassFieldMap(); + + FilteredFieldStream f(ikh, false, false); + + int max_field_index = f.field_count()-1; + + int index = 0; + for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) { + // ignore static fields + if (fld.access_flags().is_static()) { + continue; + } + field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); + } + + return field_map; +} + +// Helper class used to cache a ClassFileMap for the instance fields of +// a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during +// heap iteration and avoid creating a field map for each object in the heap +// (only need to create the map when the first instance of a class is encountered). +// +class JvmtiCachedClassFieldMap : public CHeapObj { + private: + enum { + initial_class_count = 200 + }; + ClassFieldMap* _field_map; + + ClassFieldMap* field_map() const { return _field_map; } + + JvmtiCachedClassFieldMap(ClassFieldMap* field_map); + ~JvmtiCachedClassFieldMap(); + + static GrowableArray<instanceKlass*>* _class_list; + static void add_to_class_list(instanceKlass* ik); + + public: + // returns the field map for a given object (returning map cached + // by instanceKlass if possible + static ClassFieldMap* get_map_of_instance_fields(oop obj); + + // removes the field map from all instanceKlasses - should be + // called before VM operation completes + static void clear_cache(); + + // returns the number of ClassFieldMap cached by instanceKlasses + static int cached_field_map_count(); +}; + +GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list; + +JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) { + _field_map = field_map; +} + +JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() { + if (_field_map != NULL) { + delete _field_map; + } +} + +// Marker class to ensure that the class file map cache is only used in a defined +// scope. +class ClassFieldMapCacheMark : public StackObj { + private: + static bool _is_active; + public: + ClassFieldMapCacheMark() { + assert(Thread::current()->is_VM_thread(), "must be VMThread"); + assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty"); + assert(!_is_active, "ClassFieldMapCacheMark cannot be nested"); + _is_active = true; + } + ~ClassFieldMapCacheMark() { + JvmtiCachedClassFieldMap::clear_cache(); + _is_active = false; + } + static bool is_active() { return _is_active; } +}; + +bool ClassFieldMapCacheMark::_is_active; + + +// record that the given instanceKlass is caching a field map +void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) { + if (_class_list == NULL) { + _class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true); + } + _class_list->push(ik); +} + +// returns the instance field map for the given object +// (returns field map cached by the instanceKlass if possible) +ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) { + assert(Thread::current()->is_VM_thread(), "must be VMThread"); + assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active"); + + klassOop k = obj->klass(); + instanceKlass* ik = instanceKlass::cast(k); + + // return cached map if possible + JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); + if (cached_map != NULL) { + assert(cached_map->field_map() != NULL, "missing field list"); + return cached_map->field_map(); + } else { + ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj); + cached_map = new JvmtiCachedClassFieldMap(field_map); + ik->set_jvmti_cached_class_field_map(cached_map); + add_to_class_list(ik); + return field_map; + } +} + +// remove the fields maps cached from all instanceKlasses +void JvmtiCachedClassFieldMap::clear_cache() { + assert(Thread::current()->is_VM_thread(), "must be VMThread"); + if (_class_list != NULL) { + for (int i = 0; i < _class_list->length(); i++) { + instanceKlass* ik = _class_list->at(i); + JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); + assert(cached_map != NULL, "should not be NULL"); + ik->set_jvmti_cached_class_field_map(NULL); + delete cached_map; // deletes the encapsulated field map + } + delete _class_list; + _class_list = NULL; + } +} + +// returns the number of ClassFieldMap cached by instanceKlasses +int JvmtiCachedClassFieldMap::cached_field_map_count() { + return (_class_list == NULL) ? 0 : _class_list->length(); +} + +// helper function to indicate if an object is filtered by its tag or class tag +static inline bool is_filtered_by_heap_filter(jlong obj_tag, + jlong klass_tag, + int heap_filter) { + // apply the heap filter + if (obj_tag != 0) { + // filter out tagged objects + if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true; + } else { + // filter out untagged objects + if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true; + } + if (klass_tag != 0) { + // filter out objects with tagged classes + if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true; + } else { + // filter out objects with untagged classes. + if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true; + } + return false; +} + +// helper function to indicate if an object is filtered by a klass filter +static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) { + if (!klass_filter.is_null()) { + if (obj->klass() != klass_filter()) { + return true; + } + } + return false; +} + +// helper function to tell if a field is a primitive field or not +static inline bool is_primitive_field_type(char type) { + return (type != 'L' && type != '['); +} + +// helper function to copy the value from location addr to jvalue. +static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) { + switch (value_type) { + case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; } + case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; } + default: ShouldNotReachHere(); + } +} + +// helper function to invoke string primitive value callback +// returns visit control flags +static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb, + CallbackWrapper* wrapper, + oop str, + void* user_data) +{ + assert(str->klass() == SystemDictionary::string_klass(), "not a string"); + + // get the string value and length + // (string value may be offset from the base) + int s_len = java_lang_String::length(str); + typeArrayOop s_value = java_lang_String::value(str); + int s_offset = java_lang_String::offset(str); + jchar* value; + if (s_len > 0) { + value = s_value->char_at_addr(s_offset); + } else { + value = (jchar*) s_value->base(T_CHAR); + } + + // invoke the callback + return (*cb)(wrapper->klass_tag(), + wrapper->obj_size(), + wrapper->obj_tag_p(), + value, + (jint)s_len, + user_data); +} + +// helper function to invoke string primitive value callback +// returns visit control flags +static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb, + CallbackWrapper* wrapper, + oop obj, + void* user_data) +{ + assert(obj->is_typeArray(), "not a primitive array"); + + // get base address of first element + typeArrayOop array = typeArrayOop(obj); + BasicType type = typeArrayKlass::cast(array->klass())->element_type(); + void* elements = array->base(type); + + // jvmtiPrimitiveType is defined so this mapping is always correct + jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type); + + return (*cb)(wrapper->klass_tag(), + wrapper->obj_size(), + wrapper->obj_tag_p(), + (jint)array->length(), + elem_type, + elements, + user_data); +} + +// helper function to invoke the primitive field callback for all static fields +// of a given class +static jint invoke_primitive_field_callback_for_static_fields + (CallbackWrapper* wrapper, + oop obj, + jvmtiPrimitiveFieldCallback cb, + void* user_data) +{ + // for static fields only the index will be set + static jvmtiHeapReferenceInfo reference_info = { 0 }; + + assert(obj->klass() == SystemDictionary::class_klass(), "not a class"); + if (java_lang_Class::is_primitive(obj)) { + return 0; + } + klassOop k = java_lang_Class::as_klassOop(obj); + Klass* klass = k->klass_part(); + + // ignore classes for object and type arrays + if (!klass->oop_is_instance()) { + return 0; + } + + // ignore classes which aren't linked yet + instanceKlass* ik = instanceKlass::cast(k); + if (!ik->is_linked()) { + return 0; + } + + // get the field map + ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k); + + // invoke the callback for each static primitive field + for (int i=0; i<field_map->field_count(); i++) { + ClassFieldDescriptor* field = field_map->field_at(i); + + // ignore non-primitive fields + char type = field->field_type(); + if (!is_primitive_field_type(type)) { + continue; + } + // one-to-one mapping + jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; + + // get offset and field value + int offset = field->field_offset(); + address addr = (address)k + offset; + jvalue value; + copy_to_jvalue(&value, addr, value_type); + + // field index + reference_info.field.index = field->field_index(); + + // invoke the callback + jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD, + &reference_info, + wrapper->klass_tag(), + wrapper->obj_tag_p(), + value, + value_type, + user_data); + if (res & JVMTI_VISIT_ABORT) { + delete field_map; + return res; + } + } + + delete field_map; + return 0; +} + +// helper function to invoke the primitive field callback for all instance fields +// of a given object +static jint invoke_primitive_field_callback_for_instance_fields( + CallbackWrapper* wrapper, + oop obj, + jvmtiPrimitiveFieldCallback cb, + void* user_data) +{ + // for instance fields only the index will be set + static jvmtiHeapReferenceInfo reference_info = { 0 }; + + // get the map of the instance fields + ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj); + + // invoke the callback for each instance primitive field + for (int i=0; i<fields->field_count(); i++) { + ClassFieldDescriptor* field = fields->field_at(i); + + // ignore non-primitive fields + char type = field->field_type(); + if (!is_primitive_field_type(type)) { + continue; + } + // one-to-one mapping + jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; + + // get offset and field value + int offset = field->field_offset(); + address addr = (address)obj + offset; + jvalue value; + copy_to_jvalue(&value, addr, value_type); + + // field index + reference_info.field.index = field->field_index(); + + // invoke the callback + jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD, + &reference_info, + wrapper->klass_tag(), + wrapper->obj_tag_p(), + value, + value_type, + user_data); + if (res & JVMTI_VISIT_ABORT) { + return res; + } + } + return 0; +} + + +// VM operation to iterate over all objects in the heap (both reachable +// and unreachable) +class VM_HeapIterateOperation: public VM_Operation { + private: + ObjectClosure* _blk; + public: + VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; } + + VMOp_Type type() const { return VMOp_HeapIterateOperation; } + void doit() { + // allows class files maps to be cached during iteration + ClassFieldMapCacheMark cm; + + // make sure that heap is parsable (fills TLABs with filler objects) + Universe::heap()->ensure_parsability(false); // no need to retire TLABs + + // Verify heap before iteration - if the heap gets corrupted then + // JVMTI's IterateOverHeap will crash. + if (VerifyBeforeIteration) { + Universe::verify(); + } + + // do the iteration + Universe::heap()->object_iterate(_blk); + + // when sharing is enabled we must iterate over the shared spaces + if (UseSharedSpaces) { + GenCollectedHeap* gch = GenCollectedHeap::heap(); + CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen(); + gen->ro_space()->object_iterate(_blk); + gen->rw_space()->object_iterate(_blk); + } + } + +}; + + +// An ObjectClosure used to support the deprecated IterateOverHeap and +// IterateOverInstancesOfClass functions +class IterateOverHeapObjectClosure: public ObjectClosure { + private: + JvmtiTagMap* _tag_map; + KlassHandle _klass; + jvmtiHeapObjectFilter _object_filter; + jvmtiHeapObjectCallback _heap_object_callback; + const void* _user_data; + + // accessors + JvmtiTagMap* tag_map() const { return _tag_map; } + jvmtiHeapObjectFilter object_filter() const { return _object_filter; } + jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; } + KlassHandle klass() const { return _klass; } + const void* user_data() const { return _user_data; } + + // indicates if iteration has been aborted + bool _iteration_aborted; + bool is_iteration_aborted() const { return _iteration_aborted; } + void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; } + + public: + IterateOverHeapObjectClosure(JvmtiTagMap* tag_map, + KlassHandle klass, + jvmtiHeapObjectFilter object_filter, + jvmtiHeapObjectCallback heap_object_callback, + const void* user_data) : + _tag_map(tag_map), + _klass(klass), + _object_filter(object_filter), + _heap_object_callback(heap_object_callback), + _user_data(user_data), + _iteration_aborted(false) + { + } + + void do_object(oop o); +}; + +// invoked for each object in the heap +void IterateOverHeapObjectClosure::do_object(oop o) { + // check if iteration has been halted + if (is_iteration_aborted()) return; + + // ignore any objects that aren't visible to profiler + if (!ServiceUtil::visible_oop(o)) return; + + // instanceof check when filtering by klass + if (!klass().is_null() && !o->is_a(klass()())) { + return; + } + // prepare for the calllback + CallbackWrapper wrapper(tag_map(), o); + + // if the object is tagged and we're only interested in untagged objects + // then don't invoke the callback. Similiarly, if the object is untagged + // and we're only interested in tagged objects we skip the callback. + if (wrapper.obj_tag() != 0) { + if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return; + } else { + if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return; + } + + // invoke the agent's callback + jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + (void*)user_data()); + if (control == JVMTI_ITERATION_ABORT) { + set_iteration_aborted(true); + } +} + +// An ObjectClosure used to support the IterateThroughHeap function +class IterateThroughHeapObjectClosure: public ObjectClosure { + private: + JvmtiTagMap* _tag_map; + KlassHandle _klass; + int _heap_filter; + const jvmtiHeapCallbacks* _callbacks; + const void* _user_data; + + // accessor functions + JvmtiTagMap* tag_map() const { return _tag_map; } + int heap_filter() const { return _heap_filter; } + const jvmtiHeapCallbacks* callbacks() const { return _callbacks; } + KlassHandle klass() const { return _klass; } + const void* user_data() const { return _user_data; } + + // indicates if the iteration has been aborted + bool _iteration_aborted; + bool is_iteration_aborted() const { return _iteration_aborted; } + + // used to check the visit control flags. If the abort flag is set + // then we set the iteration aborted flag so that the iteration completes + // without processing any further objects + bool check_flags_for_abort(jint flags) { + bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0; + if (is_abort) { + _iteration_aborted = true; + } + return is_abort; + } + + public: + IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map, + KlassHandle klass, + int heap_filter, + const jvmtiHeapCallbacks* heap_callbacks, + const void* user_data) : + _tag_map(tag_map), + _klass(klass), + _heap_filter(heap_filter), + _callbacks(heap_callbacks), + _user_data(user_data), + _iteration_aborted(false) + { + } + + void do_object(oop o); +}; + +// invoked for each object in the heap +void IterateThroughHeapObjectClosure::do_object(oop obj) { + // check if iteration has been halted + if (is_iteration_aborted()) return; + + // ignore any objects that aren't visible to profiler + if (!ServiceUtil::visible_oop(obj)) return; + + // apply class filter + if (is_filtered_by_klass_filter(obj, klass())) return; + + // prepare for callback + CallbackWrapper wrapper(tag_map(), obj); + + // check if filtered by the heap filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) { + return; + } + + // for arrays we need the length, otherwise -1 + bool is_array = obj->is_array(); + int len = is_array ? arrayOop(obj)->length() : -1; + + // invoke the object callback (if callback is provided) + if (callbacks()->heap_iteration_callback != NULL) { + jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback; + jint res = (*cb)(wrapper.klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + (jint)len, + (void*)user_data()); + if (check_flags_for_abort(res)) return; + } + + // for objects and classes we report primitive fields if callback provided + if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) { + jint res; + jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback; + if (obj->klass() == SystemDictionary::class_klass()) { + res = invoke_primitive_field_callback_for_static_fields(&wrapper, + obj, + cb, + (void*)user_data()); + } else { + res = invoke_primitive_field_callback_for_instance_fields(&wrapper, + obj, + cb, + (void*)user_data()); + } + if (check_flags_for_abort(res)) return; + } + + // string callback + if (!is_array && + callbacks()->string_primitive_value_callback != NULL && + obj->klass() == SystemDictionary::string_klass()) { + jint res = invoke_string_value_callback( + callbacks()->string_primitive_value_callback, + &wrapper, + obj, + (void*)user_data() ); + if (check_flags_for_abort(res)) return; + } + + // array callback + if (is_array && + callbacks()->array_primitive_value_callback != NULL && + obj->is_typeArray()) { + jint res = invoke_array_primitive_value_callback( + callbacks()->array_primitive_value_callback, + &wrapper, + obj, + (void*)user_data() ); + if (check_flags_for_abort(res)) return; + } +}; + + +// Deprecated function to iterate over all objects in the heap +void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter, + KlassHandle klass, + jvmtiHeapObjectCallback heap_object_callback, + const void* user_data) +{ + MutexLocker ml(Heap_lock); + IterateOverHeapObjectClosure blk(this, + klass, + object_filter, + heap_object_callback, + user_data); + VM_HeapIterateOperation op(&blk); + VMThread::execute(&op); +} + + +// Iterates over all objects in the heap +void JvmtiTagMap::iterate_through_heap(jint heap_filter, + KlassHandle klass, + const jvmtiHeapCallbacks* callbacks, + const void* user_data) +{ + MutexLocker ml(Heap_lock); + IterateThroughHeapObjectClosure blk(this, + klass, + heap_filter, + callbacks, + user_data); + VM_HeapIterateOperation op(&blk); + VMThread::execute(&op); +} + +// support class for get_objects_with_tags + +class TagObjectCollector : public JvmtiTagHashmapEntryClosure { + private: + JvmtiEnv* _env; + jlong* _tags; + jint _tag_count; + + GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs) + GrowableArray<uint64_t>* _tag_results; // collected tags + + public: + TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) { + _env = env; + _tags = (jlong*)tags; + _tag_count = tag_count; + _object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true); + _tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true); + } + + ~TagObjectCollector() { + delete _object_results; + delete _tag_results; + } + + // for each tagged object check if the tag value matches + // - if it matches then we create a JNI local reference to the object + // and record the reference and tag value. + // + void do_entry(JvmtiTagHashmapEntry* entry) { + for (int i=0; i<_tag_count; i++) { + if (_tags[i] == entry->tag()) { + oop o = JNIHandles::resolve(entry->object()); + assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check"); + + // the mirror is tagged + if (o->is_klass()) { + klassOop k = (klassOop)o; + o = Klass::cast(k)->java_mirror(); + } + + jobject ref = JNIHandles::make_local(JavaThread::current(), o); + _object_results->append(ref); + _tag_results->append((uint64_t)entry->tag()); + } + } + } + + // return the results from the collection + // + jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { + jvmtiError error; + int count = _object_results->length(); + assert(count >= 0, "sanity check"); + + // if object_result_ptr is not NULL then allocate the result and copy + // in the object references. + if (object_result_ptr != NULL) { + error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr); + if (error != JVMTI_ERROR_NONE) { + return error; + } + for (int i=0; i<count; i++) { + (*object_result_ptr)[i] = _object_results->at(i); + } + } + + // if tag_result_ptr is not NULL then allocate the result and copy + // in the tag values. + if (tag_result_ptr != NULL) { + error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr); + if (error != JVMTI_ERROR_NONE) { + if (object_result_ptr != NULL) { + _env->Deallocate((unsigned char*)object_result_ptr); + } + return error; + } + for (int i=0; i<count; i++) { + (*tag_result_ptr)[i] = (jlong)_tag_results->at(i); + } + } + + *count_ptr = count; + return JVMTI_ERROR_NONE; + } +}; + +// return the list of objects with the specified tags +jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags, + jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { + + TagObjectCollector collector(env(), tags, count); + { + // iterate over all tagged objects + MutexLocker ml(lock()); + entry_iterate(&collector); + } + return collector.result(count_ptr, object_result_ptr, tag_result_ptr); +} + + +// ObjectMarker is used to support the marking objects when walking the +// heap. +// +// This implementation uses the existing mark bits in an object for +// marking. Objects that are marked must later have their headers restored. +// As most objects are unlocked and don't have their identity hash computed +// we don't have to save their headers. Instead we save the headers that +// are "interesting". Later when the headers are restored this implementation +// restores all headers to their initial value and then restores the few +// objects that had interesting headers. +// +// Future work: This implementation currently uses growable arrays to save +// the oop and header of interesting objects. As an optimization we could +// use the same technique as the GC and make use of the unused area +// between top() and end(). +// + +// An ObjectClosure used to restore the mark bits of an object +class RestoreMarksClosure : public ObjectClosure { + public: + void do_object(oop o) { + if (o != NULL) { + markOop mark = o->mark(); + if (mark->is_marked()) { + o->init_mark(); + } + } + } +}; + +// ObjectMarker provides the mark and visited functions +class ObjectMarker : AllStatic { + private: + // saved headers + static GrowableArray<oop>* _saved_oop_stack; + static GrowableArray<markOop>* _saved_mark_stack; + + public: + static void init(); // initialize + static void done(); // clean-up + + static inline void mark(oop o); // mark an object + static inline bool visited(oop o); // check if object has been visited +}; + +GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL; +GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL; + +// initialize ObjectMarker - prepares for object marking +void ObjectMarker::init() { + assert(Thread::current()->is_VM_thread(), "must be VMThread"); + + // prepare heap for iteration + Universe::heap()->ensure_parsability(false); // no need to retire TLABs + + // create stacks for interesting headers + _saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true); + _saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); + + if (UseBiasedLocking) { + BiasedLocking::preserve_marks(); + } +} + +// Object marking is done so restore object headers +void ObjectMarker::done() { + // iterate over all objects and restore the mark bits to + // their initial value + RestoreMarksClosure blk; + Universe::heap()->object_iterate(&blk); + + // When sharing is enabled we need to restore the headers of the objects + // in the readwrite space too. + if (UseSharedSpaces) { + GenCollectedHeap* gch = GenCollectedHeap::heap(); + CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen(); + gen->rw_space()->object_iterate(&blk); + } + + // now restore the interesting headers + for (int i = 0; i < _saved_oop_stack->length(); i++) { + oop o = _saved_oop_stack->at(i); + markOop mark = _saved_mark_stack->at(i); + o->set_mark(mark); + } + + if (UseBiasedLocking) { + BiasedLocking::restore_marks(); + } + + // free the stacks + delete _saved_oop_stack; + delete _saved_mark_stack; +} + +// mark an object +inline void ObjectMarker::mark(oop o) { + assert(Universe::heap()->is_in(o), "sanity check"); + assert(!o->mark()->is_marked(), "should only mark an object once"); + + // object's mark word + markOop mark = o->mark(); + + if (mark->must_be_preserved(o)) { + _saved_mark_stack->push(mark); + _saved_oop_stack->push(o); + } + + // mark the object + o->set_mark(markOopDesc::prototype()->set_marked()); +} + +// return true if object is marked +inline bool ObjectMarker::visited(oop o) { + return o->mark()->is_marked(); +} + +// Stack allocated class to help ensure that ObjectMarker is used +// correctly. Constructor initializes ObjectMarker, destructor calls +// ObjectMarker's done() function to restore object headers. +class ObjectMarkerController : public StackObj { + public: + ObjectMarkerController() { + ObjectMarker::init(); + } + ~ObjectMarkerController() { + ObjectMarker::done(); + } +}; + + +// helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind +// (not performance critical as only used for roots) +static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) { + switch (kind) { + case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL; + case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS; + case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR; + case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL; + case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL; + case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD; + case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER; + default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER; + } +} + +// Base class for all heap walk contexts. The base class maintains a flag +// to indicate if the context is valid or not. +class HeapWalkContext VALUE_OBJ_CLASS_SPEC { + private: + bool _valid; + public: + HeapWalkContext(bool valid) { _valid = valid; } + void invalidate() { _valid = false; } + bool is_valid() const { return _valid; } +}; + +// A basic heap walk context for the deprecated heap walking functions. +// The context for a basic heap walk are the callbacks and fields used by +// the referrer caching scheme. +class BasicHeapWalkContext: public HeapWalkContext { + private: + jvmtiHeapRootCallback _heap_root_callback; + jvmtiStackReferenceCallback _stack_ref_callback; + jvmtiObjectReferenceCallback _object_ref_callback; + + // used for caching + oop _last_referrer; + jlong _last_referrer_tag; + + public: + BasicHeapWalkContext() : HeapWalkContext(false) { } + + BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback, + jvmtiStackReferenceCallback stack_ref_callback, + jvmtiObjectReferenceCallback object_ref_callback) : + HeapWalkContext(true), + _heap_root_callback(heap_root_callback), + _stack_ref_callback(stack_ref_callback), + _object_ref_callback(object_ref_callback), + _last_referrer(NULL), + _last_referrer_tag(0) { + } + + // accessors + jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; } + jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; } + jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; } + + oop last_referrer() const { return _last_referrer; } + void set_last_referrer(oop referrer) { _last_referrer = referrer; } + jlong last_referrer_tag() const { return _last_referrer_tag; } + void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; } +}; + +// The advanced heap walk context for the FollowReferences functions. +// The context is the callbacks, and the fields used for filtering. +class AdvancedHeapWalkContext: public HeapWalkContext { + private: + jint _heap_filter; + KlassHandle _klass_filter; + const jvmtiHeapCallbacks* _heap_callbacks; + + public: + AdvancedHeapWalkContext() : HeapWalkContext(false) { } + + AdvancedHeapWalkContext(jint heap_filter, + KlassHandle klass_filter, + const jvmtiHeapCallbacks* heap_callbacks) : + HeapWalkContext(true), + _heap_filter(heap_filter), + _klass_filter(klass_filter), + _heap_callbacks(heap_callbacks) { + } + + // accessors + jint heap_filter() const { return _heap_filter; } + KlassHandle klass_filter() const { return _klass_filter; } + + const jvmtiHeapReferenceCallback heap_reference_callback() const { + return _heap_callbacks->heap_reference_callback; + }; + const jvmtiPrimitiveFieldCallback primitive_field_callback() const { + return _heap_callbacks->primitive_field_callback; + } + const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const { + return _heap_callbacks->array_primitive_value_callback; + } + const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const { + return _heap_callbacks->string_primitive_value_callback; + } +}; + +// The CallbackInvoker is a class with static functions that the heap walk can call +// into to invoke callbacks. It works in one of two modes. The "basic" mode is +// used for the deprecated IterateOverReachableObjects functions. The "advanced" +// mode is for the newer FollowReferences function which supports a lot of +// additional callbacks. +class CallbackInvoker : AllStatic { + private: + // heap walk styles + enum { basic, advanced }; + static int _heap_walk_type; + static bool is_basic_heap_walk() { return _heap_walk_type == basic; } + static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; } + + // context for basic style heap walk + static BasicHeapWalkContext _basic_context; + static BasicHeapWalkContext* basic_context() { + assert(_basic_context.is_valid(), "invalid"); + return &_basic_context; + } + + // context for advanced style heap walk + static AdvancedHeapWalkContext _advanced_context; + static AdvancedHeapWalkContext* advanced_context() { + assert(_advanced_context.is_valid(), "invalid"); + return &_advanced_context; + } + + // context needed for all heap walks + static JvmtiTagMap* _tag_map; + static const void* _user_data; + static GrowableArray<oop>* _visit_stack; + + // accessors + static JvmtiTagMap* tag_map() { return _tag_map; } + static const void* user_data() { return _user_data; } + static GrowableArray<oop>* visit_stack() { return _visit_stack; } + + // if the object hasn't been visited then push it onto the visit stack + // so that it will be visited later + static inline bool check_for_visit(oop obj) { + if (!ObjectMarker::visited(obj)) visit_stack()->push(obj); + return true; + } + + // invoke basic style callbacks + static inline bool invoke_basic_heap_root_callback + (jvmtiHeapRootKind root_kind, oop obj); + static inline bool invoke_basic_stack_ref_callback + (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method, + int slot, oop obj); + static inline bool invoke_basic_object_reference_callback + (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index); + + // invoke advanced style callbacks + static inline bool invoke_advanced_heap_root_callback + (jvmtiHeapReferenceKind ref_kind, oop obj); + static inline bool invoke_advanced_stack_ref_callback + (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth, + jmethodID method, jlocation bci, jint slot, oop obj); + static inline bool invoke_advanced_object_reference_callback + (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index); + + // used to report the value of primitive fields + static inline bool report_primitive_field + (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type); + + public: + // initialize for basic mode + static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, + GrowableArray<oop>* visit_stack, + const void* user_data, + BasicHeapWalkContext context); + + // initialize for advanced mode + static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, + GrowableArray<oop>* visit_stack, + const void* user_data, + AdvancedHeapWalkContext context); + + // functions to report roots + static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o); + static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth, + jmethodID m, oop o); + static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth, + jmethodID method, jlocation bci, jint slot, oop o); + + // functions to report references + static inline bool report_array_element_reference(oop referrer, oop referree, jint index); + static inline bool report_class_reference(oop referrer, oop referree); + static inline bool report_class_loader_reference(oop referrer, oop referree); + static inline bool report_signers_reference(oop referrer, oop referree); + static inline bool report_protection_domain_reference(oop referrer, oop referree); + static inline bool report_superclass_reference(oop referrer, oop referree); + static inline bool report_interface_reference(oop referrer, oop referree); + static inline bool report_static_field_reference(oop referrer, oop referree, jint slot); + static inline bool report_field_reference(oop referrer, oop referree, jint slot); + static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index); + static inline bool report_primitive_array_values(oop array); + static inline bool report_string_value(oop str); + static inline bool report_primitive_instance_field(oop o, jint index, address value, char type); + static inline bool report_primitive_static_field(oop o, jint index, address value, char type); +}; + +// statics +int CallbackInvoker::_heap_walk_type; +BasicHeapWalkContext CallbackInvoker::_basic_context; +AdvancedHeapWalkContext CallbackInvoker::_advanced_context; +JvmtiTagMap* CallbackInvoker::_tag_map; +const void* CallbackInvoker::_user_data; +GrowableArray<oop>* CallbackInvoker::_visit_stack; + +// initialize for basic heap walk (IterateOverReachableObjects et al) +void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, + GrowableArray<oop>* visit_stack, + const void* user_data, + BasicHeapWalkContext context) { + _tag_map = tag_map; + _visit_stack = visit_stack; + _user_data = user_data; + _basic_context = context; + _advanced_context.invalidate(); // will trigger assertion if used + _heap_walk_type = basic; +} + +// initialize for advanced heap walk (FollowReferences) +void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, + GrowableArray<oop>* visit_stack, + const void* user_data, + AdvancedHeapWalkContext context) { + _tag_map = tag_map; + _visit_stack = visit_stack; + _user_data = user_data; + _advanced_context = context; + _basic_context.invalidate(); // will trigger assertion if used + _heap_walk_type = advanced; +} + + +// invoke basic style heap root callback +inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) { + assert(ServiceUtil::visible_oop(obj), "checking"); + + // if we heap roots should be reported + jvmtiHeapRootCallback cb = basic_context()->heap_root_callback(); + if (cb == NULL) { + return check_for_visit(obj); + } + + CallbackWrapper wrapper(tag_map(), obj); + jvmtiIterationControl control = (*cb)(root_kind, + wrapper.klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + (void*)user_data()); + // push root to visit stack when following references + if (control == JVMTI_ITERATION_CONTINUE && + basic_context()->object_ref_callback() != NULL) { + visit_stack()->push(obj); + } + return control != JVMTI_ITERATION_ABORT; +} + +// invoke basic style stack ref callback +inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind, + jlong thread_tag, + jint depth, + jmethodID method, + jint slot, + oop obj) { + assert(ServiceUtil::visible_oop(obj), "checking"); + + // if we stack refs should be reported + jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback(); + if (cb == NULL) { + return check_for_visit(obj); + } + + CallbackWrapper wrapper(tag_map(), obj); + jvmtiIterationControl control = (*cb)(root_kind, + wrapper.klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + thread_tag, + depth, + method, + slot, + (void*)user_data()); + // push root to visit stack when following references + if (control == JVMTI_ITERATION_CONTINUE && + basic_context()->object_ref_callback() != NULL) { + visit_stack()->push(obj); + } + return control != JVMTI_ITERATION_ABORT; +} + +// invoke basic style object reference callback +inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind, + oop referrer, + oop referree, + jint index) { + + assert(ServiceUtil::visible_oop(referrer), "checking"); + assert(ServiceUtil::visible_oop(referree), "checking"); + + BasicHeapWalkContext* context = basic_context(); + + // callback requires the referrer's tag. If it's the same referrer + // as the last call then we use the cached value. + jlong referrer_tag; + if (referrer == context->last_referrer()) { + referrer_tag = context->last_referrer_tag(); + } else { + referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer)); + } + + // do the callback + CallbackWrapper wrapper(tag_map(), referree); + jvmtiObjectReferenceCallback cb = context->object_ref_callback(); + jvmtiIterationControl control = (*cb)(ref_kind, + wrapper.klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + referrer_tag, + index, + (void*)user_data()); + + // record referrer and referrer tag. For self-references record the + // tag value from the callback as this might differ from referrer_tag. + context->set_last_referrer(referrer); + if (referrer == referree) { + context->set_last_referrer_tag(*wrapper.obj_tag_p()); + } else { + context->set_last_referrer_tag(referrer_tag); + } + + if (control == JVMTI_ITERATION_CONTINUE) { + return check_for_visit(referree); + } else { + return control != JVMTI_ITERATION_ABORT; + } +} + +// invoke advanced style heap root callback +inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind, + oop obj) { + assert(ServiceUtil::visible_oop(obj), "checking"); + + AdvancedHeapWalkContext* context = advanced_context(); + + // check that callback is provided + jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); + if (cb == NULL) { + return check_for_visit(obj); + } + + // apply class filter + if (is_filtered_by_klass_filter(obj, context->klass_filter())) { + return check_for_visit(obj); + } + + // setup the callback wrapper + CallbackWrapper wrapper(tag_map(), obj); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return check_for_visit(obj); + } + + // for arrays we need the length, otherwise -1 + jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); + + // invoke the callback + jint res = (*cb)(ref_kind, + NULL, // referrer info + wrapper.klass_tag(), + 0, // referrer_class_tag is 0 for heap root + wrapper.obj_size(), + wrapper.obj_tag_p(), + NULL, // referrer_tag_p + len, + (void*)user_data()); + if (res & JVMTI_VISIT_ABORT) { + return false;// referrer class tag + } + if (res & JVMTI_VISIT_OBJECTS) { + check_for_visit(obj); + } + return true; +} + +// report a reference from a thread stack to an object +inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind, + jlong thread_tag, + jlong tid, + int depth, + jmethodID method, + jlocation bci, + jint slot, + oop obj) { + assert(ServiceUtil::visible_oop(obj), "checking"); + + AdvancedHeapWalkContext* context = advanced_context(); + + // check that callback is provider + jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); + if (cb == NULL) { + return check_for_visit(obj); + } + + // apply class filter + if (is_filtered_by_klass_filter(obj, context->klass_filter())) { + return check_for_visit(obj); + } + + // setup the callback wrapper + CallbackWrapper wrapper(tag_map(), obj); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return check_for_visit(obj); + } + + // setup the referrer info + jvmtiHeapReferenceInfo reference_info; + reference_info.stack_local.thread_tag = thread_tag; + reference_info.stack_local.thread_id = tid; + reference_info.stack_local.depth = depth; + reference_info.stack_local.method = method; + reference_info.stack_local.location = bci; + reference_info.stack_local.slot = slot; + + // for arrays we need the length, otherwise -1 + jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); + + // call into the agent + int res = (*cb)(ref_kind, + &reference_info, + wrapper.klass_tag(), + 0, // referrer_class_tag is 0 for heap root (stack) + wrapper.obj_size(), + wrapper.obj_tag_p(), + NULL, // referrer_tag is 0 for root + len, + (void*)user_data()); + + if (res & JVMTI_VISIT_ABORT) { + return false; + } + if (res & JVMTI_VISIT_OBJECTS) { + check_for_visit(obj); + } + return true; +} + +// This mask is used to pass reference_info to a jvmtiHeapReferenceCallback +// only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed. +#define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \ + | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \ + | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \ + | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \ + | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \ + | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL)) + +// invoke the object reference callback to report a reference +inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind, + oop referrer, + oop obj, + jint index) +{ + // field index is only valid field in reference_info + static jvmtiHeapReferenceInfo reference_info = { 0 }; + + assert(ServiceUtil::visible_oop(referrer), "checking"); + assert(ServiceUtil::visible_oop(obj), "checking"); + + AdvancedHeapWalkContext* context = advanced_context(); + + // check that callback is provider + jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); + if (cb == NULL) { + return check_for_visit(obj); + } + + // apply class filter + if (is_filtered_by_klass_filter(obj, context->klass_filter())) { + return check_for_visit(obj); + } + + // setup the callback wrapper + TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return check_for_visit(obj); + } + + // field index is only valid field in reference_info + reference_info.field.index = index; + + // for arrays we need the length, otherwise -1 + jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); + + // invoke the callback + int res = (*cb)(ref_kind, + (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL, + wrapper.klass_tag(), + wrapper.referrer_klass_tag(), + wrapper.obj_size(), + wrapper.obj_tag_p(), + wrapper.referrer_tag_p(), + len, + (void*)user_data()); + + if (res & JVMTI_VISIT_ABORT) { + return false; + } + if (res & JVMTI_VISIT_OBJECTS) { + check_for_visit(obj); + } + return true; +} + +// report a "simple root" +inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) { + assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL && + kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root"); + assert(ServiceUtil::visible_oop(obj), "checking"); + + if (is_basic_heap_walk()) { + // map to old style root kind + jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind); + return invoke_basic_heap_root_callback(root_kind, obj); + } else { + assert(is_advanced_heap_walk(), "wrong heap walk type"); + return invoke_advanced_heap_root_callback(kind, obj); + } +} + + +// invoke the primitive array values +inline bool CallbackInvoker::report_primitive_array_values(oop obj) { + assert(obj->is_typeArray(), "not a primitive array"); + + AdvancedHeapWalkContext* context = advanced_context(); + assert(context->array_primitive_value_callback() != NULL, "no callback"); + + // apply class filter + if (is_filtered_by_klass_filter(obj, context->klass_filter())) { + return true; + } + + CallbackWrapper wrapper(tag_map(), obj); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return true; + } + + // invoke the callback + int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(), + &wrapper, + obj, + (void*)user_data()); + return (!(res & JVMTI_VISIT_ABORT)); +} + +// invoke the string value callback +inline bool CallbackInvoker::report_string_value(oop str) { + assert(str->klass() == SystemDictionary::string_klass(), "not a string"); + + AdvancedHeapWalkContext* context = advanced_context(); + assert(context->string_primitive_value_callback() != NULL, "no callback"); + + // apply class filter + if (is_filtered_by_klass_filter(str, context->klass_filter())) { + return true; + } + + CallbackWrapper wrapper(tag_map(), str); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return true; + } + + // invoke the callback + int res = invoke_string_value_callback(context->string_primitive_value_callback(), + &wrapper, + str, + (void*)user_data()); + return (!(res & JVMTI_VISIT_ABORT)); +} + +// invoke the primitive field callback +inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind, + oop obj, + jint index, + address addr, + char type) +{ + // for primitive fields only the index will be set + static jvmtiHeapReferenceInfo reference_info = { 0 }; + + AdvancedHeapWalkContext* context = advanced_context(); + assert(context->primitive_field_callback() != NULL, "no callback"); + + // apply class filter + if (is_filtered_by_klass_filter(obj, context->klass_filter())) { + return true; + } + + CallbackWrapper wrapper(tag_map(), obj); + + // apply tag filter + if (is_filtered_by_heap_filter(wrapper.obj_tag(), + wrapper.klass_tag(), + context->heap_filter())) { + return true; + } + + // the field index in the referrer + reference_info.field.index = index; + + // map the type + jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; + + // setup the jvalue + jvalue value; + copy_to_jvalue(&value, addr, value_type); + + jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback(); + int res = (*cb)(ref_kind, + &reference_info, + wrapper.klass_tag(), + wrapper.obj_tag_p(), + value, + value_type, + (void*)user_data()); + return (!(res & JVMTI_VISIT_ABORT)); +} + + +// instance field +inline bool CallbackInvoker::report_primitive_instance_field(oop obj, + jint index, + address value, + char type) { + return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD, + obj, + index, + value, + type); +} + +// static field +inline bool CallbackInvoker::report_primitive_static_field(oop obj, + jint index, + address value, + char type) { + return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD, + obj, + index, + value, + type); +} + +// report a JNI local (root object) to the profiler +inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) { + if (is_basic_heap_walk()) { + return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL, + thread_tag, + depth, + m, + -1, + obj); + } else { + return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL, + thread_tag, tid, + depth, + m, + (jlocation)-1, + -1, + obj); + } +} + + +// report a local (stack reference, root object) +inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag, + jlong tid, + jint depth, + jmethodID method, + jlocation bci, + jint slot, + oop obj) { + if (is_basic_heap_walk()) { + return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL, + thread_tag, + depth, + method, + slot, + obj); + } else { + return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL, + thread_tag, + tid, + depth, + method, + bci, + slot, + obj); + } +} + +// report an object referencing a class. +inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1); + } +} + +// report a class referencing its class loader. +inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1); + } +} + +// report a class referencing its signers. +inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1); + } +} + +// report a class referencing its protection domain.. +inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); + } +} + +// report a class referencing its superclass. +inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + // Send this to be consistent with past implementation + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1); + } +} + +// report a class referencing one of its interfaces. +inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1); + } +} + +// report a class referencing one of its static fields. +inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot); + } +} + +// report an array referencing an element object +inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); + } +} + +// report an object referencing an instance field object +inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot); + } +} + +// report an array referencing an element object +inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) { + if (is_basic_heap_walk()) { + return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index); + } else { + return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index); + } +} + +// A supporting closure used to process simple roots +class SimpleRootsClosure : public OopClosure { + private: + jvmtiHeapReferenceKind _kind; + bool _continue; + + jvmtiHeapReferenceKind root_kind() { return _kind; } + + public: + void set_kind(jvmtiHeapReferenceKind kind) { + _kind = kind; + _continue = true; + } + + inline bool stopped() { + return !_continue; + } + + void do_oop(oop* obj_p) { + // iteration has terminated + if (stopped()) { + return; + } + + // ignore null or deleted handles + oop o = *obj_p; + if (o == NULL || o == JNIHandles::deleted_handle()) { + return; + } + + jvmtiHeapReferenceKind kind = root_kind(); + + // many roots are Klasses so we use the java mirror + if (o->is_klass()) { + klassOop k = (klassOop)o; + o = Klass::cast(k)->java_mirror(); + } else { + + // SystemDictionary::always_strong_oops_do reports the application + // class loader as a root. We want this root to be reported as + // a root kind of "OTHER" rather than "SYSTEM_CLASS". + if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) { + kind = JVMTI_HEAP_REFERENCE_OTHER; + } + } + + // some objects are ignored - in the case of simple + // roots it's mostly symbolOops that we are skipping + // here. + if (!ServiceUtil::visible_oop(o)) { + return; + } + + // invoke the callback + _continue = CallbackInvoker::report_simple_root(kind, o); + + } +}; + +// A supporting closure used to process JNI locals +class JNILocalRootsClosure : public OopClosure { + private: + jlong _thread_tag; + jlong _tid; + jint _depth; + jmethodID _method; + bool _continue; + public: + void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) { + _thread_tag = thread_tag; + _tid = tid; + _depth = depth; + _method = method; + _continue = true; + } + + inline bool stopped() { + return !_continue; + } + + void do_oop(oop* obj_p) { + // iteration has terminated + if (stopped()) { + return; + } + + // ignore null or deleted handles + oop o = *obj_p; + if (o == NULL || o == JNIHandles::deleted_handle()) { + return; + } + + if (!ServiceUtil::visible_oop(o)) { + return; + } + + // invoke the callback + _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o); + } +}; + + +// A VM operation to iterate over objects that are reachable from +// a set of roots or an initial object. +// +// For VM_HeapWalkOperation the set of roots used is :- +// +// - All JNI global references +// - All inflated monitors +// - All classes loaded by the boot class loader (or all classes +// in the event that class unloading is disabled) +// - All java threads +// - For each java thread then all locals and JNI local references +// on the thread's execution stack +// - All visible/explainable objects from Universes::oops_do +// +class VM_HeapWalkOperation: public VM_Operation { + private: + enum { + initial_visit_stack_size = 4000 + }; + + bool _is_advanced_heap_walk; // indicates FollowReferences + JvmtiTagMap* _tag_map; + Handle _initial_object; + GrowableArray<oop>* _visit_stack; // the visit stack + + bool _collecting_heap_roots; // are we collecting roots + bool _following_object_refs; // are we following object references + + bool _reporting_primitive_fields; // optional reporting + bool _reporting_primitive_array_values; + bool _reporting_string_values; + + GrowableArray<oop>* create_visit_stack() { + return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true); + } + + // accessors + bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; } + JvmtiTagMap* tag_map() const { return _tag_map; } + Handle initial_object() const { return _initial_object; } + + bool is_following_references() const { return _following_object_refs; } + + bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; } + bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; } + bool is_reporting_string_values() const { return _reporting_string_values; } + + GrowableArray<oop>* visit_stack() const { return _visit_stack; } + + // iterate over the various object types + inline bool iterate_over_array(oop o); + inline bool iterate_over_type_array(oop o); + inline bool iterate_over_class(klassOop o); + inline bool iterate_over_object(oop o); + + // root collection + inline bool collect_simple_roots(); + inline bool collect_stack_roots(); + inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk); + + // visit an object + inline bool visit(oop o); + + public: + VM_HeapWalkOperation(JvmtiTagMap* tag_map, + Handle initial_object, + BasicHeapWalkContext callbacks, + const void* user_data); + + VM_HeapWalkOperation(JvmtiTagMap* tag_map, + Handle initial_object, + AdvancedHeapWalkContext callbacks, + const void* user_data); + + ~VM_HeapWalkOperation(); + + VMOp_Type type() const { return VMOp_HeapWalkOperation; } + void doit(); +}; + + +VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, + Handle initial_object, + BasicHeapWalkContext callbacks, + const void* user_data) { + _is_advanced_heap_walk = false; + _tag_map = tag_map; + _initial_object = initial_object; + _following_object_refs = (callbacks.object_ref_callback() != NULL); + _reporting_primitive_fields = false; + _reporting_primitive_array_values = false; + _reporting_string_values = false; + _visit_stack = create_visit_stack(); + + + CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks); +} + +VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, + Handle initial_object, + AdvancedHeapWalkContext callbacks, + const void* user_data) { + _is_advanced_heap_walk = true; + _tag_map = tag_map; + _initial_object = initial_object; + _following_object_refs = true; + _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);; + _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);; + _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);; + _visit_stack = create_visit_stack(); + + CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks); +} + +VM_HeapWalkOperation::~VM_HeapWalkOperation() { + if (_following_object_refs) { + assert(_visit_stack != NULL, "checking"); + delete _visit_stack; + _visit_stack = NULL; + } +} + +// an array references its class and has a reference to +// each element in the array +inline bool VM_HeapWalkOperation::iterate_over_array(oop o) { + objArrayOop array = objArrayOop(o); + if (array->klass() == Universe::systemObjArrayKlassObj()) { + // filtered out + return true; + } + + // array reference to its class + oop mirror = objArrayKlass::cast(array->klass())->java_mirror(); + if (!CallbackInvoker::report_class_reference(o, mirror)) { + return false; + } + + // iterate over the array and report each reference to a + // non-null element + for (int index=0; index<array->length(); index++) { + oop elem = array->obj_at(index); + if (elem == NULL) { + continue; + } + + // report the array reference o[index] = elem + if (!CallbackInvoker::report_array_element_reference(o, elem, index)) { + return false; + } + } + return true; +} + +// a type array references its class +inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) { + klassOop k = o->klass(); + oop mirror = Klass::cast(k)->java_mirror(); + if (!CallbackInvoker::report_class_reference(o, mirror)) { + return false; + } + + // report the array contents if required + if (is_reporting_primitive_array_values()) { + if (!CallbackInvoker::report_primitive_array_values(o)) { + return false; + } + } + return true; +} + +// verify that a static oop field is in range +static inline bool verify_static_oop(instanceKlass* ik, oop* obj_p) { + oop* start = ik->start_of_static_fields(); + oop* end = start + ik->static_oop_field_size(); + assert(end >= start, "sanity check"); + + if (obj_p >= start && obj_p < end) { + return true; + } else { + return false; + } +} + +// a class references its super class, interfaces, class loader, ... +// and finally its static fields +inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) { + int i; + Klass* klass = klassOop(k)->klass_part(); + + if (klass->oop_is_instance()) { + instanceKlass* ik = instanceKlass::cast(k); + + // ignore the class if it's has been initialized yet + if (!ik->is_linked()) { + return true; + } + + // get the java mirror + oop mirror = klass->java_mirror(); + + // super (only if something more interesting than java.lang.Object) + klassOop java_super = ik->java_super(); + if (java_super != NULL && java_super != SystemDictionary::object_klass()) { + oop super = Klass::cast(java_super)->java_mirror(); + if (!CallbackInvoker::report_superclass_reference(mirror, super)) { + return false; + } + } + + // class loader + oop cl = ik->class_loader(); + if (cl != NULL) { + if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) { + return false; + } + } + + // protection domain + oop pd = ik->protection_domain(); + if (pd != NULL) { + if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) { + return false; + } + } + + // signers + oop signers = ik->signers(); + if (signers != NULL) { + if (!CallbackInvoker::report_signers_reference(mirror, signers)) { + return false; + } + } + + // references from the constant pool + { + const constantPoolOop pool = ik->constants(); + for (int i = 1; i < pool->length(); i++) { + constantTag tag = pool->tag_at(i).value(); + if (tag.is_string() || tag.is_klass()) { + oop entry; + if (tag.is_string()) { + entry = pool->resolved_string_at(i); + assert(java_lang_String::is_instance(entry), "must be string"); + } else { + entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror(); + } + if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) { + return false; + } + } + } + } + + // interfaces + // (These will already have been reported as references from the constant pool + // but are specified by IterateOverReachableObjects and must be reported). + objArrayOop interfaces = ik->local_interfaces(); + for (i = 0; i < interfaces->length(); i++) { + oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror(); + if (interf == NULL) { + continue; + } + if (!CallbackInvoker::report_interface_reference(mirror, interf)) { + return false; + } + } + + // iterate over the static fields + + ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k); + for (i=0; i<field_map->field_count(); i++) { + ClassFieldDescriptor* field = field_map->field_at(i); + char type = field->field_type(); + if (!is_primitive_field_type(type)) { + address addr = (address)k + field->field_offset(); + oop* f = (oop*)addr; + assert(verify_static_oop(ik, f), "sanity check"); + oop fld_o = *f; + if (fld_o != NULL) { + int slot = field->field_index(); + if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) { + delete field_map; + return false; + } + } + } else { + if (is_reporting_primitive_fields()) { + address addr = (address)k + field->field_offset(); + int slot = field->field_index(); + if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) { + delete field_map; + return false; + } + } + } + } + delete field_map; + + return true; + } + + return true; +} + +// an object references a class and its instance fields +// (static fields are ignored here as we report these as +// references from the class). +inline bool VM_HeapWalkOperation::iterate_over_object(oop o) { + // reference to the class + if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) { + return false; + } + + // iterate over instance fields + ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o); + for (int i=0; i<field_map->field_count(); i++) { + ClassFieldDescriptor* field = field_map->field_at(i); + char type = field->field_type(); + if (!is_primitive_field_type(type)) { + address addr = (address)o + field->field_offset(); + oop* f = (oop*)addr; + oop fld_o = *f; + if (fld_o != NULL) { + // reflection code may have a reference to a klassOop. + // - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe + if (fld_o->is_klass()) { + klassOop k = (klassOop)fld_o; + fld_o = Klass::cast(k)->java_mirror(); + } + int slot = field->field_index(); + if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) { + return false; + } + } + } else { + if (is_reporting_primitive_fields()) { + // primitive instance field + address addr = (address)o + field->field_offset(); + int slot = field->field_index(); + if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) { + return false; + } + } + } + } + + // if the object is a java.lang.String + if (is_reporting_string_values() && + o->klass() == SystemDictionary::string_klass()) { + if (!CallbackInvoker::report_string_value(o)) { + return false; + } + } + return true; +} + + +// collects all simple (non-stack) roots. +// if there's a heap root callback provided then the callback is +// invoked for each simple root. +// if an object reference callback is provided then all simple +// roots are pushed onto the marking stack so that they can be +// processed later +// +inline bool VM_HeapWalkOperation::collect_simple_roots() { + SimpleRootsClosure blk; + + // JNI globals + blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL); + JNIHandles::oops_do(&blk); + if (blk.stopped()) { + return false; + } + + // Preloaded classes and loader from the system dictionary + blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS); + SystemDictionary::always_strong_oops_do(&blk); + if (blk.stopped()) { + return false; + } + + // Inflated monitors + blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR); + ObjectSynchronizer::oops_do(&blk); + if (blk.stopped()) { + return false; + } + + // Threads + for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) { + oop threadObj = thread->threadObj(); + if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { + bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj); + if (!cont) { + return false; + } + } + } + + // Other kinds of roots maintained by HotSpot + // Many of these won't be visible but others (such as instances of important + // exceptions) will be visible. + blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); + Universe::oops_do(&blk); + return true; +} + +// Walk the stack of a given thread and find all references (locals +// and JNI calls) and report these as stack references +inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread, + JNILocalRootsClosure* blk) +{ + oop threadObj = java_thread->threadObj(); + assert(threadObj != NULL, "sanity check"); + + // only need to get the thread's tag once per thread + jlong thread_tag = tag_for(_tag_map, threadObj); + + // also need the thread id + jlong tid = java_lang_Thread::thread_id(threadObj); + + + if (java_thread->has_last_Java_frame()) { + + // vframes are resource allocated + Thread* current_thread = Thread::current(); + ResourceMark rm(current_thread); + HandleMark hm(current_thread); + + RegisterMap reg_map(java_thread); + frame f = java_thread->last_frame(); + vframe* vf = vframe::new_vframe(&f, ®_map, java_thread); + + bool is_top_frame = true; + int depth = 0; + frame* last_entry_frame = NULL; + + while (vf != NULL) { + if (vf->is_java_frame()) { + + // java frame (interpreted, compiled, ...) + javaVFrame *jvf = javaVFrame::cast(vf); + + // the jmethodID + jmethodID method = jvf->method()->jmethod_id(); + + if (!(jvf->method()->is_native())) { + jlocation bci = (jlocation)jvf->bci(); + StackValueCollection* locals = jvf->locals(); + for (int slot=0; slot<locals->size(); slot++) { + if (locals->at(slot)->type() == T_OBJECT) { + oop o = locals->obj_at(slot)(); + if (o == NULL) { + continue; + } + + // stack reference + if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method, + bci, slot, o)) { + return false; + } + } + } + } else { + blk->set_context(thread_tag, tid, depth, method); + if (is_top_frame) { + // JNI locals for the top frame. + java_thread->active_handles()->oops_do(blk); + } else { + if (last_entry_frame != NULL) { + // JNI locals for the entry frame + assert(last_entry_frame->is_entry_frame(), "checking"); + last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk); + } + } + } + last_entry_frame = NULL; + depth++; + } else { + // externalVFrame - for an entry frame then we report the JNI locals + // when we find the corresponding javaVFrame + frame* fr = vf->frame_pointer(); + assert(fr != NULL, "sanity check"); + if (fr->is_entry_frame()) { + last_entry_frame = fr; + } + } + + vf = vf->sender(); + is_top_frame = false; + } + } else { + // no last java frame but there may be JNI locals + blk->set_context(thread_tag, tid, 0, (jmethodID)NULL); + java_thread->active_handles()->oops_do(blk); + } + return true; +} + + +// collects all stack roots - for each thread it walks the execution +// stack to find all references and local JNI refs. +inline bool VM_HeapWalkOperation::collect_stack_roots() { + JNILocalRootsClosure blk; + for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) { + oop threadObj = thread->threadObj(); + if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { + if (!collect_stack_roots(thread, &blk)) { + return false; + } + } + } + return true; +} + +// visit an object +// first mark the object as visited +// second get all the outbound references from this object (in other words, all +// the objects referenced by this object). +// +bool VM_HeapWalkOperation::visit(oop o) { + // mark object as visited + assert(!ObjectMarker::visited(o), "can't visit same object more than once"); + ObjectMarker::mark(o); + + // instance + if (o->is_instance()) { + if (o->klass() == SystemDictionary::class_klass()) { + o = klassOop_if_java_lang_Class(o); + if (o->is_klass()) { + // a java.lang.Class + return iterate_over_class(klassOop(o)); + } + } else { + return iterate_over_object(o); + } + } + + // object array + if (o->is_objArray()) { + return iterate_over_array(o); + } + + // type array + if (o->is_typeArray()) { + return iterate_over_type_array(o); + } + + return true; +} + +void VM_HeapWalkOperation::doit() { + ResourceMark rm; + ObjectMarkerController marker; + ClassFieldMapCacheMark cm; + + assert(visit_stack()->is_empty(), "visit stack must be empty"); + + // the heap walk starts with an initial object or the heap roots + if (initial_object().is_null()) { + if (!collect_simple_roots()) return; + if (!collect_stack_roots()) return; + } else { + visit_stack()->push(initial_object()()); + } + + // object references required + if (is_following_references()) { + + // visit each object until all reachable objects have been + // visited or the callback asked to terminate the iteration. + while (!visit_stack()->is_empty()) { + oop o = visit_stack()->pop(); + if (!ObjectMarker::visited(o)) { + if (!visit(o)) { + break; + } + } + } + } +} + +// iterate over all objects that are reachable from a set of roots +void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, + jvmtiStackReferenceCallback stack_ref_callback, + jvmtiObjectReferenceCallback object_ref_callback, + const void* user_data) { + MutexLocker ml(Heap_lock); + BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback); + VM_HeapWalkOperation op(this, Handle(), context, user_data); + VMThread::execute(&op); +} + +// iterate over all objects that are reachable from a given object +void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object, + jvmtiObjectReferenceCallback object_ref_callback, + const void* user_data) { + oop obj = JNIHandles::resolve(object); + Handle initial_object(Thread::current(), obj); + + MutexLocker ml(Heap_lock); + BasicHeapWalkContext context(NULL, NULL, object_ref_callback); + VM_HeapWalkOperation op(this, initial_object, context, user_data); + VMThread::execute(&op); +} + +// follow references from an initial object or the GC roots +void JvmtiTagMap::follow_references(jint heap_filter, + KlassHandle klass, + jobject object, + const jvmtiHeapCallbacks* callbacks, + const void* user_data) +{ + oop obj = JNIHandles::resolve(object); + Handle initial_object(Thread::current(), obj); + + MutexLocker ml(Heap_lock); + AdvancedHeapWalkContext context(heap_filter, klass, callbacks); + VM_HeapWalkOperation op(this, initial_object, context, user_data); + VMThread::execute(&op); +} + + +// called post-GC +// - for each JVMTI environment with an object tag map, call its rehash +// function to re-sync with the new object locations. +void JvmtiTagMap::gc_epilogue(bool full) { + assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); + if (JvmtiEnv::environments_might_exist()) { + // re-obtain the memory region for the young generation (might + // changed due to adaptive resizing policy) + get_young_generation(); + + JvmtiEnvIterator it; + for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) { + JvmtiTagMap* tag_map = env->tag_map(); + if (tag_map != NULL && !tag_map->is_empty()) { + TraceTime t(full ? "JVMTI Full Rehash " : "JVMTI Rehash ", TraceJVMTIObjectTagging); + if (full) { + tag_map->rehash(0, n_hashmaps); + } else { + tag_map->rehash(0, 0); // tag map for young gen only + } + } + } + } +} + +// CMS has completed referencing processing so we may have JNI weak refs +// to objects in the CMS generation that have been GC'ed. +void JvmtiTagMap::cms_ref_processing_epilogue() { + assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); + assert(UseConcMarkSweepGC, "should only be used with CMS"); + if (JvmtiEnv::environments_might_exist()) { + JvmtiEnvIterator it; + for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) { + JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map(); + if (tag_map != NULL && !tag_map->is_empty()) { + TraceTime t("JVMTI Rehash (CMS) ", TraceJVMTIObjectTagging); + tag_map->rehash(1, n_hashmaps); // assume CMS not used in young gen + } + } + } +} + + +// For each entry in the hashmaps 'start' to 'end' : +// +// 1. resolve the JNI weak reference +// +// 2. If it resolves to NULL it means the object has been freed so the entry +// is removed, the weak reference destroyed, and the object free event is +// posted (if enabled). +// +// 3. If the weak reference resolves to an object then we re-hash the object +// to see if it has moved or has been promoted (from the young to the old +// generation for example). +// +void JvmtiTagMap::rehash(int start, int end) { + + // does this environment have the OBJECT_FREE event enabled + bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE); + + // counters used for trace message + int freed = 0; + int moved = 0; + int promoted = 0; + + // we assume there are two hashmaps - one for the young generation + // and the other for all other spaces. + assert(n_hashmaps == 2, "not implemented"); + JvmtiTagHashmap* young_hashmap = _hashmap[0]; + JvmtiTagHashmap* other_hashmap = _hashmap[1]; + + // reenable sizing (if disabled) + young_hashmap->set_resizing_enabled(true); + other_hashmap->set_resizing_enabled(true); + + // when re-hashing the hashmap corresponding to the young generation we + // collect the entries corresponding to objects that have been promoted. + JvmtiTagHashmapEntry* promoted_entries = NULL; + + if (end >= n_hashmaps) { + end = n_hashmaps - 1; + } + + for (int i=start; i <= end; i++) { + JvmtiTagHashmap* hashmap = _hashmap[i]; + + // if the hashmap is empty then we can skip it + if (hashmap->_entry_count == 0) { + continue; + } + + // now iterate through each entry in the table + + JvmtiTagHashmapEntry** table = hashmap->table(); + int size = hashmap->size(); + + for (int pos=0; pos<size; pos++) { + JvmtiTagHashmapEntry* entry = table[pos]; + JvmtiTagHashmapEntry* prev = NULL; + + while (entry != NULL) { + JvmtiTagHashmapEntry* next = entry->next(); + + jweak ref = entry->object(); + oop oop = JNIHandles::resolve(ref); + + // has object been GC'ed + if (oop == NULL) { + // grab the tag + jlong tag = entry->tag(); + guarantee(tag != 0, "checking"); + + // remove GC'ed entry from hashmap and return the + // entry to the free list + hashmap->remove(prev, pos, entry); + destroy_entry(entry); + + // destroy the weak ref + JNIHandles::destroy_weak_global(ref); + + // post the event to the profiler + if (post_object_free) { + JvmtiExport::post_object_free(env(), tag); + } + + freed++; + entry = next; + continue; + } + + // if this is the young hashmap then the object is either promoted + // or moved. + // if this is the other hashmap then the object is moved. + + bool same_gen; + if (i == 0) { + assert(hashmap == young_hashmap, "checking"); + same_gen = is_in_young(oop); + } else { + same_gen = true; + } + + + if (same_gen) { + // if the object has moved then re-hash it and move its + // entry to its new location. + unsigned int new_pos = JvmtiTagHashmap::hash(oop, size); + if (new_pos != (unsigned int)pos) { + if (prev == NULL) { + table[pos] = next; + } else { + prev->set_next(next); + } + entry->set_next(table[new_pos]); + table[new_pos] = entry; + moved++; + } else { + // object didn't move + prev = entry; + } + } else { + // object has been promoted so remove the entry from the + // young hashmap + assert(hashmap == young_hashmap, "checking"); + hashmap->remove(prev, pos, entry); + + // move the entry to the promoted list + entry->set_next(promoted_entries); + promoted_entries = entry; + } + + entry = next; + } + } + } + + + // add the entries, corresponding to the promoted objects, to the + // other hashmap. + JvmtiTagHashmapEntry* entry = promoted_entries; + while (entry != NULL) { + oop o = JNIHandles::resolve(entry->object()); + assert(hashmap_for(o) == other_hashmap, "checking"); + JvmtiTagHashmapEntry* next = entry->next(); + other_hashmap->add(o, entry); + entry = next; + promoted++; + } + + // stats + if (TraceJVMTIObjectTagging) { + int total_moves = promoted + moved; + + int post_total = 0; + for (int i=0; i<n_hashmaps; i++) { + post_total += _hashmap[i]->_entry_count; + } + int pre_total = post_total + freed; + + tty->print("(%d->%d, %d freed, %d promoted, %d total moves)", + pre_total, post_total, freed, promoted, total_moves); + } +}