Mercurial > hg > truffle
view src/share/vm/prims/jvmtiTagMap.cpp @ 4898:d851f3714641
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author | dholmes |
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date | Wed, 25 Jan 2012 19:26:35 -0500 |
parents | 88dce6a60ac8 |
children | 2b150750d53d |
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/* * Copyright (c) 2003, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/symbolTable.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "jvmtifiles/jvmtiEnv.hpp" #include "oops/instanceMirrorKlass.hpp" #include "oops/objArrayKlass.hpp" #include "oops/oop.inline2.hpp" #include "prims/jvmtiEventController.hpp" #include "prims/jvmtiEventController.inline.hpp" #include "prims/jvmtiExport.hpp" #include "prims/jvmtiImpl.hpp" #include "prims/jvmtiTagMap.hpp" #include "runtime/biasedLocking.hpp" #include "runtime/javaCalls.hpp" #include "runtime/jniHandles.hpp" #include "runtime/mutex.hpp" #include "runtime/mutexLocker.hpp" #include "runtime/reflectionUtils.hpp" #include "runtime/vframe.hpp" #include "runtime/vmThread.hpp" #include "runtime/vm_operations.hpp" #include "services/serviceUtil.hpp" #ifndef SERIALGC #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" #endif // JvmtiTagHashmapEntry // // Each entry encapsulates a 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; oop _object; // tagged object jlong _tag; // the tag JvmtiTagHashmapEntry* _next; // next on the list inline void init(oop object, jlong tag) { _object = object; _tag = tag; _next = NULL; } // constructor JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); } public: // accessor methods inline oop object() const { return _object; } inline oop* object_addr() { 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 tag value. // // 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 = 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) { if (entry->object() == key) { return entry; } entry = entry->next(); } return NULL; } // 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) { if (key == entry->object()) { 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; } } } // 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"); _hashmap = new JvmtiTagHashmap(); // 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); JvmtiTagHashmapEntry** table = _hashmap->table(); for (int j = 0; j < _hashmap->size(); j++) { JvmtiTagHashmapEntry* entry = table[j]; while (entry != NULL) { JvmtiTagHashmapEntry* next = entry->next(); delete entry; entry = next; } } // finally destroy the hashmap delete _hashmap; _hashmap = NULL; // remove any entries on the free list JvmtiTagHashmapEntry* entry = _free_entries; while (entry != NULL) { JvmtiTagHashmapEntry* next = entry->next(); delete entry; entry = next; } _free_entries = NULL; } // 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(oop 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) { hashmap()->entry_iterate(closure); } // returns true if the hashmaps are empty bool JvmtiTagMap::is_empty() { assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); return hashmap()->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()->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(); _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"); entry = tag_map()->create_entry(o, 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) { JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o); assert(entry_removed == entry, "checking"); tag_map()->destroy_entry(entry); } 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(); _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. 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; JvmtiTagHashmapEntry* entry = hashmap->find(o); // if the object is not already tagged then we tag it if (entry == NULL) { if (tag != 0) { entry = create_entry(o, tag); hashmap->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. if (tag == 0) { hashmap->remove(o); destroy_entry(entry); } 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 // If this operation encounters a bad object when using CMS, // consider using safe_object_iterate() which avoids perm gen // objects that may contain bad references. 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 = entry->object(); assert(o != NULL, "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; static bool _needs_reset; // do we need to reset mark bits? 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 static inline bool needs_reset() { return _needs_reset; } static inline void set_needs_reset(bool v) { _needs_reset = v; } }; GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL; GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL; bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default // 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; if (needs_reset()) { Universe::heap()->object_iterate(&blk); } else { // We don't need to reset mark bits on this call, but reset the // flag to the default for the next call. set_needs_reset(true); } // 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(); if (o == NULL) { // Classes without mirrors don't correspond to real Java // classes so just ignore them. return; } } 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 Symbol*s that we are skipping // here. if (!ServiceUtil::visible_oop(o)) { return; } // invoke the callback _continue = CallbackInvoker::report_simple_root(kind, o); } virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } }; // 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); } virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } }; // 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 mirror, int offset) { address obj_p = (address)mirror + offset; address start = (address)instanceMirrorKlass::start_of_static_fields(mirror); address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize); 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)) { oop fld_o = mirror->obj_field(field->field_offset()); assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check"); 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)mirror + 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)) { oop fld_o = o->obj_field(field->field_offset()); 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 except for threads; // threads are handled in collect_stack_roots() as an optimization. // 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 are now handled in collect_stack_roots() // 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); // If there are any non-perm roots in the code cache, visit them. blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); CodeBlobToOopClosure look_in_blobs(&blk, false); CodeCache::scavenge_root_nmethods_do(&look_in_blobs); 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; } if (fr->is_ricochet_frame()) { fr->oops_ricochet_do(blk, vf->register_map()); } } 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 the simple roots for all threads and 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()) { // Collect the simple root for this thread before we // collect its stack roots if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) { return false; } 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 either collect_stack_roots() or collect_simple_roots() // returns false at this point, then there are no mark bits // to reset. ObjectMarker::set_needs_reset(false); // Calling collect_stack_roots() before collect_simple_roots() // can result in a big performance boost for an agent that is // focused on analyzing references in the thread stacks. if (!collect_stack_roots()) return; if (!collect_simple_roots()) return; // no early return so enable heap traversal to reset the mark bits ObjectMarker::set_needs_reset(true); } 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); } void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) { // No locks during VM bring-up (0 threads) and no safepoints after main // thread creation and before VMThread creation (1 thread); initial GC // verification can happen in that window which gets to here. assert(Threads::number_of_threads() <= 1 || SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); if (JvmtiEnv::environments_might_exist()) { 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()) { tag_map->do_weak_oops(is_alive, f); } } } } void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) { // 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; JvmtiTagHashmap* hashmap = this->hashmap(); // reenable sizing (if disabled) hashmap->set_resizing_enabled(true); // if the hashmap is empty then we can skip it if (hashmap->_entry_count == 0) { return; } // now iterate through each entry in the table JvmtiTagHashmapEntry** table = hashmap->table(); int size = hashmap->size(); JvmtiTagHashmapEntry* delayed_add = NULL; for (int pos = 0; pos < size; ++pos) { JvmtiTagHashmapEntry* entry = table[pos]; JvmtiTagHashmapEntry* prev = NULL; while (entry != NULL) { JvmtiTagHashmapEntry* next = entry->next(); oop* obj = entry->object_addr(); // has object been GC'ed if (!is_alive->do_object_b(entry->object())) { // 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); // post the event to the profiler if (post_object_free) { JvmtiExport::post_object_free(env(), tag); } ++freed; } else { f->do_oop(entry->object_addr()); oop new_oop = entry->object(); // if the object has moved then re-hash it and move its // entry to its new location. unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size); if (new_pos != (unsigned int)pos) { if (prev == NULL) { table[pos] = next; } else { prev->set_next(next); } if (new_pos < (unsigned int)pos) { entry->set_next(table[new_pos]); table[new_pos] = entry; } else { // Delay adding this entry to it's new position as we'd end up // hitting it again during this iteration. entry->set_next(delayed_add); delayed_add = entry; } moved++; } else { // object didn't move prev = entry; } } entry = next; } } // Re-add all the entries which were kept aside while (delayed_add != NULL) { JvmtiTagHashmapEntry* next = delayed_add->next(); unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size); delayed_add->set_next(table[pos]); table[pos] = delayed_add; delayed_add = next; } // stats if (TraceJVMTIObjectTagging) { int post_total = hashmap->_entry_count; int pre_total = post_total + freed; tty->print_cr("(%d->%d, %d freed, %d total moves)", pre_total, post_total, freed, moved); } }