truffle: src/share/vm/prims/jvmtiTagMap.cpp comparison

comparison src/share/vm/prims/jvmtiTagMap.cpp @ 0:a61af66fc99e jdk7-b24

Initial load

author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	ba764ed4b6f2

comparison

equal deleted inserted replaced

--1:000000000000
+:a61af66fc99e
+/*
+* Copyright 2003-2007 Sun Microsystems, Inc.  All Rights Reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+# include "incls/_precompiled.incl"
+# include "incls/_jvmtiTagMap.cpp.incl"
+// JvmtiTagHashmapEntry
+//
+// Each entry encapsulates a JNI weak reference to the tagged object
+// and the tag value. In addition an entry includes a next pointer which
+// is used to chain entries together.
+class JvmtiTagHashmapEntry : public CHeapObj {
+private:
+friend class JvmtiTagMap;
+jweak _object;                        // JNI weak ref to tagged object
+jlong _tag;                           // the tag
+JvmtiTagHashmapEntry* _next;          // next on the list
+inline void init(jweak object, jlong tag) {
+_object = object;
+_tag = tag;
+_next = NULL;
+}
+// constructor
+JvmtiTagHashmapEntry(jweak object, jlong tag)         { init(object, tag); }
+public:
+// accessor methods
+inline jweak object() const                           { return _object; }
+inline jlong tag() const                              { return _tag; }
+inline void set_tag(jlong tag) {
+assert(tag != 0, "can't be zero");
+_tag = tag;
+}
+inline JvmtiTagHashmapEntry* next() const             { return _next; }
+inline void set_next(JvmtiTagHashmapEntry* next)      { _next = next; }
+};
+// JvmtiTagHashmap
+//
+// A hashmap is essentially a table of pointers to entries. Entries
+// are hashed to a location, or position in the table, and then
+// chained from that location. The "key" for hashing is address of
+// the object, or oop. The "value" is the JNI weak reference to the
+// object and the tag value. Keys are not stored with the entry.
+// Instead the weak reference is resolved to obtain the key.
+//
+// A hashmap maintains a count of the number entries in the hashmap
+// and resizes if the number of entries exceeds a given threshold.
+// The threshold is specified as a percentage of the size - for
+// example a threshold of 0.75 will trigger the hashmap to resize
+// if the number of entries is >75% of table size.
+//
+// A hashmap provides functions for adding, removing, and finding
+// entries. It also provides a function to iterate over all entries
+// in the hashmap.
+class JvmtiTagHashmap : public CHeapObj {
+private:
+friend class JvmtiTagMap;
+enum {
+small_trace_threshold  = 10000,                  // threshold for tracing
+medium_trace_threshold = 100000,
+large_trace_threshold  = 1000000,
+initial_trace_threshold = small_trace_threshold
+};
+static int _sizes[];                  // array of possible hashmap sizes
+int _size;                            // actual size of the table
+int _size_index;                      // index into size table
+int _entry_count;                     // number of entries in the hashmap
+float _load_factor;                   // load factor as a % of the size
+int _resize_threshold;                // computed threshold to trigger resizing.
+bool _resizing_enabled;               // indicates if hashmap can resize
+int _trace_threshold;                 // threshold for trace messages
+JvmtiTagHashmapEntry** _table;        // the table of entries.
+// private accessors
+int resize_threshold() const                  { return _resize_threshold; }
+int trace_threshold() const                   { return _trace_threshold; }
+// initialize the hashmap
+void init(int size_index=0, float load_factor=4.0f) {
+int initial_size =  _sizes[size_index];
+_size_index = size_index;
+_size = initial_size;
+_entry_count = 0;
+if (TraceJVMTIObjectTagging) {
+_trace_threshold = initial_trace_threshold;
+} else {
+_trace_threshold = -1;
+}
+_load_factor = load_factor;
+_resize_threshold = (int)(_load_factor * _size);
+_resizing_enabled = true;
+size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
+_table = (JvmtiTagHashmapEntry**)os::malloc(s);
+if (_table == NULL) {
+vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags");
+}
+for (int i=0; i<initial_size; i++) {
+_table[i] = NULL;
+}
+}
+// hash a given key (oop) with the specified size
+static unsigned int hash(oop key, int size) {
+// shift right to get better distribution (as these bits will be zero
+// with aligned addresses)
+unsigned int addr = (unsigned int)((intptr_t)key);
+#ifdef _LP64
+return (addr >> 3) % size;
+#else
+return (addr >> 2) % size;
+#endif
+}
+// hash a given key (oop)
+unsigned int hash(oop key) {
+return hash(key, _size);
+}
+// resize the hashmap - allocates a large table and re-hashes
+// all entries into the new table.
+void resize() {
+int new_size_index = _size_index+1;
+int new_size = _sizes[new_size_index];
+if (new_size < 0) {
+// hashmap already at maximum capacity
+return;
+}
+// allocate new table
+size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
+JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s);
+if (new_table == NULL) {
+warning("unable to allocate larger hashtable for jvmti object tags");
+set_resizing_enabled(false);
+return;
+}
+// initialize new table
+int i;
+for (i=0; i<new_size; i++) {
+new_table[i] = NULL;
+}
+// rehash all entries into the new table
+for (i=0; i<_size; i++) {
+JvmtiTagHashmapEntry* entry = _table[i];
+while (entry != NULL) {
+JvmtiTagHashmapEntry* next = entry->next();
+oop key = JNIHandles::resolve(entry->object());
+assert(key != NULL, "jni weak reference cleared!!");
+unsigned int h = hash(key, new_size);
+JvmtiTagHashmapEntry* anchor = new_table[h];
+if (anchor == NULL) {
+new_table[h] = entry;
+entry->set_next(NULL);
+} else {
+entry->set_next(anchor);
+new_table[h] = entry;
+}
+entry = next;
+}
+}
+// free old table and update settings.
+os::free((void*)_table);
+_table = new_table;
+_size_index = new_size_index;
+_size = new_size;
+// compute new resize threshold
+_resize_threshold = (int)(_load_factor * _size);
+}
+// internal remove function - remove an entry at a given position in the
+// table.
+inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
+assert(pos >= 0 && pos < _size, "out of range");
+if (prev == NULL) {
+_table[pos] = entry->next();
+} else {
+prev->set_next(entry->next());
+}
+assert(_entry_count > 0, "checking");
+_entry_count--;
+}
+// resizing switch
+bool is_resizing_enabled() const          { return _resizing_enabled; }
+void set_resizing_enabled(bool enable)    { _resizing_enabled = enable; }
+// debugging
+void print_memory_usage();
+void compute_next_trace_threshold();
+public:
+// create a JvmtiTagHashmap of a preferred size and optionally a load factor.
+// The preferred size is rounded down to an actual size.
+JvmtiTagHashmap(int size, float load_factor=0.0f) {
+int i=0;
+while (_sizes[i] < size) {
+if (_sizes[i] < 0) {
+assert(i > 0, "sanity check");
+i--;
+break;
+}
+i++;
+}
+// if a load factor is specified then use it, otherwise use default
+if (load_factor > 0.01f) {
+init(i, load_factor);
+} else {
+init(i);
+}
+}
+// create a JvmtiTagHashmap with default settings
+JvmtiTagHashmap() {
+init();
+}
+// release table when JvmtiTagHashmap destroyed
+~JvmtiTagHashmap() {
+if (_table != NULL) {
+os::free((void*)_table);
+_table = NULL;
+}
+}
+// accessors
+int size() const                              { return _size; }
+JvmtiTagHashmapEntry** table() const          { return _table; }
+int entry_count() const                       { return _entry_count; }
+// find an entry in the hashmap, returns NULL if not found.
+inline JvmtiTagHashmapEntry* find(oop key) {
+unsigned int h = hash(key);
+JvmtiTagHashmapEntry* entry = _table[h];
+while (entry != NULL) {
+oop orig_key = JNIHandles::resolve(entry->object());
+assert(orig_key != NULL, "jni weak reference cleared!!");
+if (key == orig_key) {
+break;
+}
+entry = entry->next();
+}
+return entry;
+}
+// add a new entry to hashmap
+inline void add(oop key, JvmtiTagHashmapEntry* entry) {
+assert(key != NULL, "checking");
+assert(find(key) == NULL, "duplicate detected");
+unsigned int h = hash(key);
+JvmtiTagHashmapEntry* anchor = _table[h];
+if (anchor == NULL) {
+_table[h] = entry;
+entry->set_next(NULL);
+} else {
+entry->set_next(anchor);
+_table[h] = entry;
+}
+_entry_count++;
+if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
+assert(TraceJVMTIObjectTagging, "should only get here when tracing");
+print_memory_usage();
+compute_next_trace_threshold();
+}
+// if the number of entries exceed the threshold then resize
+if (entry_count() > resize_threshold() && is_resizing_enabled()) {
+resize();
+}
+}
+// remove an entry with the given key.
+inline JvmtiTagHashmapEntry* remove(oop key) {
+unsigned int h = hash(key);
+JvmtiTagHashmapEntry* entry = _table[h];
+JvmtiTagHashmapEntry* prev = NULL;
+while (entry != NULL) {
+oop orig_key = JNIHandles::resolve(entry->object());
+assert(orig_key != NULL, "jni weak reference cleared!!");
+if (key == orig_key) {
+break;
+}
+prev = entry;
+entry = entry->next();
+}
+if (entry != NULL) {
+remove(prev, h, entry);
+}
+return entry;
+}
+// iterate over all entries in the hashmap
+void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
+};
+// possible hashmap sizes - odd primes that roughly double in size.
+// To avoid excessive resizing the odd primes from 4801-76831 and
+// 76831-307261 have been removed. The list must be terminated by -1.
+int JvmtiTagHashmap::_sizes[] =  { 4801, 76831, 307261, 614563, 1228891,
+2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
+// A supporting class for iterating over all entries in Hashmap
+class JvmtiTagHashmapEntryClosure {
+public:
+virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
+};
+// iterate over all entries in the hashmap
+void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
+for (int i=0; i<_size; i++) {
+JvmtiTagHashmapEntry* entry = _table[i];
+JvmtiTagHashmapEntry* prev = NULL;
+while (entry != NULL) {
+// obtain the next entry before invoking do_entry - this is
+// necessary because do_entry may remove the entry from the
+// hashmap.
+JvmtiTagHashmapEntry* next = entry->next();
+closure->do_entry(entry);
+entry = next;
+}
+}
+}
+// debugging
+void JvmtiTagHashmap::print_memory_usage() {
+intptr_t p = (intptr_t)this;
+tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
+// table + entries in KB
+int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
+entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
+int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
+tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
+entry_count(), hashmap_usage, weak_globals_usage);
+}
+// compute threshold for the next trace message
+void JvmtiTagHashmap::compute_next_trace_threshold() {
+if (trace_threshold() < medium_trace_threshold) {
+_trace_threshold += small_trace_threshold;
+} else {
+if (trace_threshold() < large_trace_threshold) {
+_trace_threshold += medium_trace_threshold;
+} else {
+_trace_threshold += large_trace_threshold;
+}
+}
+}
+// memory region for young generation
+MemRegion JvmtiTagMap::_young_gen;
+// get the memory region used for the young generation
+void JvmtiTagMap::get_young_generation() {
+if (Universe::heap()->kind() == CollectedHeap::GenCollectedHeap) {
+GenCollectedHeap* gch = GenCollectedHeap::heap();
+_young_gen = gch->get_gen(0)->reserved();
+} else {
+#ifndef SERIALGC
+ParallelScavengeHeap* psh = ParallelScavengeHeap::heap();
+_young_gen= psh->young_gen()->reserved();
+#else  // SERIALGC
+fatal("SerialGC only supported in this configuration.");
+#endif // SERIALGC
+}
+}
+// returns true if oop is in the young generation
+inline bool JvmtiTagMap::is_in_young(oop o) {
+assert(_young_gen.start() != NULL, "checking");
+void* p = (void*)o;
+bool in_young = _young_gen.contains(p);
+return in_young;
+}
+// returns the appropriate hashmap for a given object
+inline JvmtiTagHashmap* JvmtiTagMap::hashmap_for(oop o) {
+if (is_in_young(o)) {
+return _hashmap[0];
+} else {
+return _hashmap[1];
+}
+}
+// create a JvmtiTagMap
+JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
+_env(env),
+_lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
+_free_entries(NULL),
+_free_entries_count(0)
+{
+assert(JvmtiThreadState_lock->is_locked(), "sanity check");
+assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
+// create the hashmaps
+for (int i=0; i<n_hashmaps; i++) {
+_hashmap[i] = new JvmtiTagHashmap();
+}
+// get the memory region used by the young generation
+get_young_generation();
+// finally add us to the environment
+((JvmtiEnvBase *)env)->set_tag_map(this);
+}
+// destroy a JvmtiTagMap
+JvmtiTagMap::~JvmtiTagMap() {
+// no lock acquired as we assume the enclosing environment is
+// also being destroryed.
+((JvmtiEnvBase *)_env)->set_tag_map(NULL);
+// iterate over the hashmaps and destroy each of the entries
+for (int i=0; i<n_hashmaps; i++) {
+JvmtiTagHashmap* hashmap = _hashmap[i];
+JvmtiTagHashmapEntry** table = hashmap->table();
+for (int j=0; j<hashmap->size(); j++) {
+JvmtiTagHashmapEntry *entry = table[j];
+while (entry != NULL) {
+JvmtiTagHashmapEntry* next = entry->next();
+jweak ref = entry->object();
+JNIHandles::destroy_weak_global(ref);
+delete entry;
+entry = next;
+}
+}
+// finally destroy the hashmap
+delete hashmap;
+}
+// remove any entries on the free list
+JvmtiTagHashmapEntry* entry = _free_entries;
+while (entry != NULL) {
+JvmtiTagHashmapEntry* next = entry->next();
+delete entry;
+entry = next;
+}
+}
+// create a hashmap entry
+// - if there's an entry on the (per-environment) free list then this
+// is returned. Otherwise an new entry is allocated.
+JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) {
+assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
+JvmtiTagHashmapEntry* entry;
+if (_free_entries == NULL) {
+entry = new JvmtiTagHashmapEntry(ref, tag);
+} else {
+assert(_free_entries_count > 0, "mismatched _free_entries_count");
+_free_entries_count--;
+entry = _free_entries;
+_free_entries = entry->next();
+entry->init(ref, tag);
+}
+return entry;
+}
+// destroy an entry by returning it to the free list
+void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
+assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
+// limit the size of the free list
+if (_free_entries_count >= max_free_entries) {
+delete entry;
+} else {
+entry->set_next(_free_entries);
+_free_entries = entry;
+_free_entries_count++;
+}
+}
+// returns the tag map for the given environments. If the tag map
+// doesn't exist then it is created.
+JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
+JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
+if (tag_map == NULL) {
+MutexLocker mu(JvmtiThreadState_lock);
+tag_map = ((JvmtiEnvBase *)env)->tag_map();
+if (tag_map == NULL) {
+tag_map = new JvmtiTagMap(env);
+}
+} else {
+CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
+}
+return tag_map;
+}
+// iterate over all entries in the tag map.
+void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
+for (int i=0; i<n_hashmaps; i++) {
+JvmtiTagHashmap* hashmap = _hashmap[i];
+hashmap->entry_iterate(closure);
+}
+}
+// returns true if the hashmaps are empty
+bool JvmtiTagMap::is_empty() {
+assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
+assert(n_hashmaps == 2, "not implemented");
+return ((_hashmap[0]->entry_count() == 0) && (_hashmap[1]->entry_count() == 0));
+}
+// Return the tag value for an object, or 0 if the object is
+// not tagged
+//
+static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
+JvmtiTagHashmapEntry* entry = tag_map->hashmap_for(o)->find(o);
+if (entry == NULL) {
+return 0;
+} else {
+return entry->tag();
+}
+}
+// If the object is a java.lang.Class then return the klassOop,
+// otherwise return the original object
+static inline oop klassOop_if_java_lang_Class(oop o) {
+if (o->klass() == SystemDictionary::class_klass()) {
+if (!java_lang_Class::is_primitive(o)) {
+o = (oop)java_lang_Class::as_klassOop(o);
+assert(o != NULL, "class for non-primitive mirror must exist");
+}
+}
+return o;
+}
+// A CallbackWrapper is a support class for querying and tagging an object
+// around a callback to a profiler. The constructor does pre-callback
+// work to get the tag value, klass tag value, ... and the destructor
+// does the post-callback work of tagging or untagging the object.
+//
+// {
+//   CallbackWrapper wrapper(tag_map, o);
+//
+//   (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
+//
+// } // wrapper goes out of scope here which results in the destructor
+//      checking to see if the object has been tagged, untagged, or the
+//      tag value has changed.
+//
+class CallbackWrapper : public StackObj {
+private:
+JvmtiTagMap* _tag_map;
+JvmtiTagHashmap* _hashmap;
+JvmtiTagHashmapEntry* _entry;
+oop _o;
+jlong _obj_size;
+jlong _obj_tag;
+klassOop _klass;         // the object's class
+jlong _klass_tag;
+protected:
+JvmtiTagMap* tag_map() const      { return _tag_map; }
+// invoked post-callback to tag, untag, or update the tag of an object
+void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
+JvmtiTagHashmapEntry* entry, jlong obj_tag);
+public:
+CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
+assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
+"MT unsafe or must be VM thread");
+// for Classes the klassOop is tagged
+_o = klassOop_if_java_lang_Class(o);
+// object size
+_obj_size = _o->size() * wordSize;
+// record the context
+_tag_map = tag_map;
+_hashmap = tag_map->hashmap_for(_o);
+_entry = _hashmap->find(_o);
+// get object tag
+_obj_tag = (_entry == NULL) ? 0 : _entry->tag();
+// get the class and the class's tag value
+if (_o == o) {
+_klass = _o->klass();
+} else {
+// if the object represents a runtime class then use the
+// tag for java.lang.Class
+_klass = SystemDictionary::class_klass();
+}
+_klass_tag = tag_for(tag_map, _klass);
+}
+~CallbackWrapper() {
+post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
+}
+inline jlong* obj_tag_p()                     { return &_obj_tag; }
+inline jlong obj_size() const                 { return _obj_size; }
+inline jlong obj_tag() const                  { return _obj_tag; }
+inline klassOop klass() const                 { return _klass; }
+inline jlong klass_tag() const                { return _klass_tag; }
+};
+// callback post-callback to tag, untag, or update the tag of an object
+void inline CallbackWrapper::post_callback_tag_update(oop o,
+JvmtiTagHashmap* hashmap,
+JvmtiTagHashmapEntry* entry,
+jlong obj_tag) {
+if (entry == NULL) {
+if (obj_tag != 0) {
+// callback has tagged the object
+assert(Thread::current()->is_VM_thread(), "must be VMThread");
+HandleMark hm;
+Handle h(o);
+jweak ref = JNIHandles::make_weak_global(h);
+entry = tag_map()->create_entry(ref, obj_tag);
+hashmap->add(o, entry);
+}
+} else {
+// object was previously tagged - the callback may have untagged
+// the object or changed the tag value
+if (obj_tag == 0) {
+jweak ref = entry->object();
+JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
+assert(entry_removed == entry, "checking");
+tag_map()->destroy_entry(entry);
+JNIHandles::destroy_weak_global(ref);
+} else {
+if (obj_tag != entry->tag()) {
+entry->set_tag(obj_tag);
+}
+}
+}
+}
+// An extended CallbackWrapper used when reporting an object reference
+// to the agent.
+//
+// {
+//   TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
+//
+//   (*callback)(wrapper.klass_tag(),
+//               wrapper.obj_size(),
+//               wrapper.obj_tag_p()
+//               wrapper.referrer_tag_p(), ...)
+//
+// } // wrapper goes out of scope here which results in the destructor
+//      checking to see if the referrer object has been tagged, untagged,
+//      or the tag value has changed.
+//
+class TwoOopCallbackWrapper : public CallbackWrapper {
+private:
+bool _is_reference_to_self;
+JvmtiTagHashmap* _referrer_hashmap;
+JvmtiTagHashmapEntry* _referrer_entry;
+oop _referrer;
+jlong _referrer_obj_tag;
+jlong _referrer_klass_tag;
+jlong* _referrer_tag_p;
+bool is_reference_to_self() const             { return _is_reference_to_self; }
+public:
+TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
+CallbackWrapper(tag_map, o)
+{
+// self reference needs to be handled in a special way
+_is_reference_to_self = (referrer == o);
+if (_is_reference_to_self) {
+_referrer_klass_tag = klass_tag();
+_referrer_tag_p = obj_tag_p();
+} else {
+// for Classes the klassOop is tagged
+_referrer = klassOop_if_java_lang_Class(referrer);
+// record the context
+_referrer_hashmap = tag_map->hashmap_for(_referrer);
+_referrer_entry = _referrer_hashmap->find(_referrer);
+// get object tag
+_referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
+_referrer_tag_p = &_referrer_obj_tag;
+// get referrer class tag.
+klassOop k = (_referrer == referrer) ?  // Check if referrer is a class...
+_referrer->klass()                  // No, just get its class
+: SystemDictionary::class_klass();   // Yes, its class is Class
+_referrer_klass_tag = tag_for(tag_map, k);
+}
+}
+~TwoOopCallbackWrapper() {
+if (!is_reference_to_self()){
+post_callback_tag_update(_referrer,
+_referrer_hashmap,
+_referrer_entry,
+_referrer_obj_tag);
+}
+}
+// address of referrer tag
+// (for a self reference this will return the same thing as obj_tag_p())
+inline jlong* referrer_tag_p()        { return _referrer_tag_p; }
+// referrer's class tag
+inline jlong referrer_klass_tag()     { return _referrer_klass_tag; }
+};
+// tag an object
+//
+// This function is performance critical. If many threads attempt to tag objects
+// around the same time then it's possible that the Mutex associated with the
+// tag map will be a hot lock. Eliminating this lock will not eliminate the issue
+// because creating a JNI weak reference requires acquiring a global lock also.
+void JvmtiTagMap::set_tag(jobject object, jlong tag) {
+MutexLocker ml(lock());
+// resolve the object
+oop o = JNIHandles::resolve_non_null(object);
+// for Classes we tag the klassOop
+o = klassOop_if_java_lang_Class(o);
+// see if the object is already tagged
+JvmtiTagHashmap* hashmap = hashmap_for(o);
+JvmtiTagHashmapEntry* entry = hashmap->find(o);
+// if the object is not already tagged then we tag it
+if (entry == NULL) {
+if (tag != 0) {
+HandleMark hm;
+Handle h(o);
+jweak ref = JNIHandles::make_weak_global(h);
+// the object may have moved because make_weak_global may
+// have blocked - thus it is necessary resolve the handle
+// and re-hash the object.
+o = h();
+entry = create_entry(ref, tag);
+hashmap_for(o)->add(o, entry);
+} else {
+// no-op
+}
+} else {
+// if the object is already tagged then we either update
+// the tag (if a new tag value has been provided)
+// or remove the object if the new tag value is 0.
+// Removing the object requires that we also delete the JNI
+// weak ref to the object.
+if (tag == 0) {
+jweak ref = entry->object();
+hashmap->remove(o);
+destroy_entry(entry);
+JNIHandles::destroy_weak_global(ref);
+} else {
+entry->set_tag(tag);
+}
+}
+}
+// get the tag for an object
+jlong JvmtiTagMap::get_tag(jobject object) {
+MutexLocker ml(lock());
+// resolve the object
+oop o = JNIHandles::resolve_non_null(object);
+// for Classes get the tag from the klassOop
+return tag_for(this, klassOop_if_java_lang_Class(o));
+}
+// Helper class used to describe the static or instance fields of a class.
+// For each field it holds the field index (as defined by the JVMTI specification),
+// the field type, and the offset.
+class ClassFieldDescriptor: public CHeapObj {
+private:
+int _field_index;
+int _field_offset;
+char _field_type;
+public:
+ClassFieldDescriptor(int index, char type, int offset) :
+_field_index(index), _field_type(type), _field_offset(offset) {
+}
+int field_index()  const  { return _field_index; }
+char field_type()  const  { return _field_type; }
+int field_offset() const  { return _field_offset; }
+};
+class ClassFieldMap: public CHeapObj {
+private:
+enum {
+initial_field_count = 5
+};
+// list of field descriptors
+GrowableArray<ClassFieldDescriptor*>* _fields;
+// constructor
+ClassFieldMap();
+// add a field
+void add(int index, char type, int offset);
+// returns the field count for the given class
+static int compute_field_count(instanceKlassHandle ikh);
+public:
+~ClassFieldMap();
+// access
+int field_count()                     { return _fields->length(); }
+ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
+// functions to create maps of static or instance fields
+static ClassFieldMap* create_map_of_static_fields(klassOop k);
+static ClassFieldMap* create_map_of_instance_fields(oop obj);
+};
+ClassFieldMap::ClassFieldMap() {
+_fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
+}
+ClassFieldMap::~ClassFieldMap() {
+for (int i=0; i<_fields->length(); i++) {
+delete _fields->at(i);
+}
+delete _fields;
+}
+void ClassFieldMap::add(int index, char type, int offset) {
+ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
+_fields->append(field);
+}
+// Returns a heap allocated ClassFieldMap to describe the static fields
+// of the given class.
+//
+ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) {
+HandleMark hm;
+instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
+// create the field map
+ClassFieldMap* field_map = new ClassFieldMap();
+FilteredFieldStream f(ikh, false, false);
+int max_field_index = f.field_count()-1;
+int index = 0;
+for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
+// ignore instance fields
+if (!fld.access_flags().is_static()) {
+continue;
+}
+field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
+}
+return field_map;
+}
+// Returns a heap allocated ClassFieldMap to describe the instance fields
+// of the given class. All instance fields are included (this means public
+// and private fields declared in superclasses and superinterfaces too).
+//
+ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
+HandleMark hm;
+instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
+// create the field map
+ClassFieldMap* field_map = new ClassFieldMap();
+FilteredFieldStream f(ikh, false, false);
+int max_field_index = f.field_count()-1;
+int index = 0;
+for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
+// ignore static fields
+if (fld.access_flags().is_static()) {
+continue;
+}
+field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
+}
+return field_map;
+}
+// Helper class used to cache a ClassFileMap for the instance fields of
+// a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during
+// heap iteration and avoid creating a field map for each object in the heap
+// (only need to create the map when the first instance of a class is encountered).
+//
+class JvmtiCachedClassFieldMap : public CHeapObj {
+private:
+enum {
+initial_class_count = 200
+};
+ClassFieldMap* _field_map;
+ClassFieldMap* field_map() const          { return _field_map; }
+JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
+~JvmtiCachedClassFieldMap();
+static GrowableArray<instanceKlass*>* _class_list;
+static void add_to_class_list(instanceKlass* ik);
+public:
+// returns the field map for a given object (returning map cached
+// by instanceKlass if possible
+static ClassFieldMap* get_map_of_instance_fields(oop obj);
+// removes the field map from all instanceKlasses - should be
+// called before VM operation completes
+static void clear_cache();
+// returns the number of ClassFieldMap cached by instanceKlasses
+static int cached_field_map_count();
+};
+GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
+JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
+_field_map = field_map;
+}
+JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
+if (_field_map != NULL) {
+delete _field_map;
+}
+}
+// Marker class to ensure that the class file map cache is only used in a defined
+// scope.
+class ClassFieldMapCacheMark : public StackObj {
+private:
+static bool _is_active;
+public:
+ClassFieldMapCacheMark() {
+assert(Thread::current()->is_VM_thread(), "must be VMThread");
+assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
+assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
+_is_active = true;
+}
+~ClassFieldMapCacheMark() {
+JvmtiCachedClassFieldMap::clear_cache();
+_is_active = false;
+}
+static bool is_active() { return _is_active; }
+};
+bool ClassFieldMapCacheMark::_is_active;
+// record that the given instanceKlass is caching a field map
+void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) {
+if (_class_list == NULL) {
+_class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true);
+}
+_class_list->push(ik);
+}
+// returns the instance field map for the given object
+// (returns field map cached by the instanceKlass if possible)
+ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
+assert(Thread::current()->is_VM_thread(), "must be VMThread");
+assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
+klassOop k = obj->klass();
+instanceKlass* ik = instanceKlass::cast(k);
+// return cached map if possible
+JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
+if (cached_map != NULL) {
+assert(cached_map->field_map() != NULL, "missing field list");
+return cached_map->field_map();
+} else {
+ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
+cached_map = new JvmtiCachedClassFieldMap(field_map);
+ik->set_jvmti_cached_class_field_map(cached_map);
+add_to_class_list(ik);
+return field_map;
+}
+}
+// remove the fields maps cached from all instanceKlasses
+void JvmtiCachedClassFieldMap::clear_cache() {
+assert(Thread::current()->is_VM_thread(), "must be VMThread");
+if (_class_list != NULL) {
+for (int i = 0; i < _class_list->length(); i++) {
+instanceKlass* ik = _class_list->at(i);
+JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
+assert(cached_map != NULL, "should not be NULL");
+ik->set_jvmti_cached_class_field_map(NULL);
+delete cached_map;  // deletes the encapsulated field map
+}
+delete _class_list;
+_class_list = NULL;
+}
+}
+// returns the number of ClassFieldMap cached by instanceKlasses
+int JvmtiCachedClassFieldMap::cached_field_map_count() {
+return (_class_list == NULL) ? 0 : _class_list->length();
+}
+// helper function to indicate if an object is filtered by its tag or class tag
+static inline bool is_filtered_by_heap_filter(jlong obj_tag,
+jlong klass_tag,
+int heap_filter) {
+// apply the heap filter
+if (obj_tag != 0) {
+// filter out tagged objects
+if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
+} else {
+// filter out untagged objects
+if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
+}
+if (klass_tag != 0) {
+// filter out objects with tagged classes
+if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
+} else {
+// filter out objects with untagged classes.
+if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
+}
+return false;
+}
+// helper function to indicate if an object is filtered by a klass filter
+static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
+if (!klass_filter.is_null()) {
+if (obj->klass() != klass_filter()) {
+return true;
+}
+}
+return false;
+}
+// helper function to tell if a field is a primitive field or not
+static inline bool is_primitive_field_type(char type) {
+return (type != 'L' && type != '[');
+}
+// helper function to copy the value from location addr to jvalue.
+static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
+switch (value_type) {
+case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
+case JVMTI_PRIMITIVE_TYPE_BYTE    : { v->b = *(jbyte*)addr;    break; }
+case JVMTI_PRIMITIVE_TYPE_CHAR    : { v->c = *(jchar*)addr;    break; }
+case JVMTI_PRIMITIVE_TYPE_SHORT   : { v->s = *(jshort*)addr;   break; }
+case JVMTI_PRIMITIVE_TYPE_INT     : { v->i = *(jint*)addr;     break; }
+case JVMTI_PRIMITIVE_TYPE_LONG    : { v->j = *(jlong*)addr;    break; }
+case JVMTI_PRIMITIVE_TYPE_FLOAT   : { v->f = *(jfloat*)addr;   break; }
+case JVMTI_PRIMITIVE_TYPE_DOUBLE  : { v->d = *(jdouble*)addr;  break; }
+default: ShouldNotReachHere();
+}
+}
+// helper function to invoke string primitive value callback
+// returns visit control flags
+static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
+CallbackWrapper* wrapper,
+oop str,
+void* user_data)
+{
+assert(str->klass() == SystemDictionary::string_klass(), "not a string");
+// get the string value and length
+// (string value may be offset from the base)
+int s_len = java_lang_String::length(str);
+typeArrayOop s_value = java_lang_String::value(str);
+int s_offset = java_lang_String::offset(str);
+jchar* value;
+if (s_len > 0) {
+value = s_value->char_at_addr(s_offset);
+} else {
+value = (jchar*) s_value->base(T_CHAR);
+}
+// invoke the callback
+return (*cb)(wrapper->klass_tag(),
+wrapper->obj_size(),
+wrapper->obj_tag_p(),
+value,
+(jint)s_len,
+user_data);
+}
+// helper function to invoke string primitive value callback
+// returns visit control flags
+static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
+CallbackWrapper* wrapper,
+oop obj,
+void* user_data)
+{
+assert(obj->is_typeArray(), "not a primitive array");
+// get base address of first element
+typeArrayOop array = typeArrayOop(obj);
+BasicType type = typeArrayKlass::cast(array->klass())->element_type();
+void* elements = array->base(type);
+// jvmtiPrimitiveType is defined so this mapping is always correct
+jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
+return (*cb)(wrapper->klass_tag(),
+wrapper->obj_size(),
+wrapper->obj_tag_p(),
+(jint)array->length(),
+elem_type,
+elements,
+user_data);
+}
+// helper function to invoke the primitive field callback for all static fields
+// of a given class
+static jint invoke_primitive_field_callback_for_static_fields
+(CallbackWrapper* wrapper,
+oop obj,
+jvmtiPrimitiveFieldCallback cb,
+void* user_data)
+{
+// for static fields only the index will be set
+static jvmtiHeapReferenceInfo reference_info = { 0 };
+assert(obj->klass() == SystemDictionary::class_klass(), "not a class");
+if (java_lang_Class::is_primitive(obj)) {
+return 0;
+}
+klassOop k = java_lang_Class::as_klassOop(obj);
+Klass* klass = k->klass_part();
+// ignore classes for object and type arrays
+if (!klass->oop_is_instance()) {
+return 0;
+}
+// ignore classes which aren't linked yet
+instanceKlass* ik = instanceKlass::cast(k);
+if (!ik->is_linked()) {
+return 0;
+}
+// get the field map
+ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
+// invoke the callback for each static primitive field
+for (int i=0; i<field_map->field_count(); i++) {
+ClassFieldDescriptor* field = field_map->field_at(i);
+// ignore non-primitive fields
+char type = field->field_type();
+if (!is_primitive_field_type(type)) {
+continue;
+}
+// one-to-one mapping
+jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
+// get offset and field value
+int offset = field->field_offset();
+address addr = (address)k + offset;
+jvalue value;
+copy_to_jvalue(&value, addr, value_type);
+// field index
+reference_info.field.index = field->field_index();
+// invoke the callback
+jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
+&reference_info,
+wrapper->klass_tag(),
+wrapper->obj_tag_p(),
+value,
+value_type,
+user_data);
+if (res & JVMTI_VISIT_ABORT) {
+delete field_map;
+return res;
+}
+}
+delete field_map;
+return 0;
+}
+// helper function to invoke the primitive field callback for all instance fields
+// of a given object
+static jint invoke_primitive_field_callback_for_instance_fields(
+CallbackWrapper* wrapper,
+oop obj,
+jvmtiPrimitiveFieldCallback cb,
+void* user_data)
+{
+// for instance fields only the index will be set
+static jvmtiHeapReferenceInfo reference_info = { 0 };
+// get the map of the instance fields
+ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
+// invoke the callback for each instance primitive field
+for (int i=0; i<fields->field_count(); i++) {
+ClassFieldDescriptor* field = fields->field_at(i);
+// ignore non-primitive fields
+char type = field->field_type();
+if (!is_primitive_field_type(type)) {
+continue;
+}
+// one-to-one mapping
+jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
+// get offset and field value
+int offset = field->field_offset();
+address addr = (address)obj + offset;
+jvalue value;
+copy_to_jvalue(&value, addr, value_type);
+// field index
+reference_info.field.index = field->field_index();
+// invoke the callback
+jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
+&reference_info,
+wrapper->klass_tag(),
+wrapper->obj_tag_p(),
+value,
+value_type,
+user_data);
+if (res & JVMTI_VISIT_ABORT) {
+return res;
+}
+}
+return 0;
+}
+// VM operation to iterate over all objects in the heap (both reachable
+// and unreachable)
+class VM_HeapIterateOperation: public VM_Operation {
+private:
+ObjectClosure* _blk;
+public:
+VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
+VMOp_Type type() const { return VMOp_HeapIterateOperation; }
+void doit() {
+// allows class files maps to be cached during iteration
+ClassFieldMapCacheMark cm;
+// make sure that heap is parsable (fills TLABs with filler objects)
+Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
+// Verify heap before iteration - if the heap gets corrupted then
+// JVMTI's IterateOverHeap will crash.
+if (VerifyBeforeIteration) {
+Universe::verify();
+}
+// do the iteration
+Universe::heap()->object_iterate(_blk);
+// when sharing is enabled we must iterate over the shared spaces
+if (UseSharedSpaces) {
+GenCollectedHeap* gch = GenCollectedHeap::heap();
+CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
+gen->ro_space()->object_iterate(_blk);
+gen->rw_space()->object_iterate(_blk);
+}
+}
+};
+// An ObjectClosure used to support the deprecated IterateOverHeap and
+// IterateOverInstancesOfClass functions
+class IterateOverHeapObjectClosure: public ObjectClosure {
+private:
+JvmtiTagMap* _tag_map;
+KlassHandle _klass;
+jvmtiHeapObjectFilter _object_filter;
+jvmtiHeapObjectCallback _heap_object_callback;
+const void* _user_data;
+// accessors
+JvmtiTagMap* tag_map() const                    { return _tag_map; }
+jvmtiHeapObjectFilter object_filter() const     { return _object_filter; }
+jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
+KlassHandle klass() const                       { return _klass; }
+const void* user_data() const                   { return _user_data; }
+// indicates if iteration has been aborted
+bool _iteration_aborted;
+bool is_iteration_aborted() const               { return _iteration_aborted; }
+void set_iteration_aborted(bool aborted)        { _iteration_aborted = aborted; }
+public:
+IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
+KlassHandle klass,
+jvmtiHeapObjectFilter object_filter,
+jvmtiHeapObjectCallback heap_object_callback,
+const void* user_data) :
+_tag_map(tag_map),
+_klass(klass),
+_object_filter(object_filter),
+_heap_object_callback(heap_object_callback),
+_user_data(user_data),
+_iteration_aborted(false)
+{
+}
+void do_object(oop o);
+};
+// invoked for each object in the heap
+void IterateOverHeapObjectClosure::do_object(oop o) {
+// check if iteration has been halted
+if (is_iteration_aborted()) return;
+// ignore any objects that aren't visible to profiler
+if (!ServiceUtil::visible_oop(o)) return;
+// instanceof check when filtering by klass
+if (!klass().is_null() && !o->is_a(klass()())) {
+return;
+}
+// prepare for the calllback
+CallbackWrapper wrapper(tag_map(), o);
+// if the object is tagged and we're only interested in untagged objects
+// then don't invoke the callback. Similiarly, if the object is untagged
+// and we're only interested in tagged objects we skip the callback.
+if (wrapper.obj_tag() != 0) {
+if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
+} else {
+if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
+}
+// invoke the agent's callback
+jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+(void*)user_data());
+if (control == JVMTI_ITERATION_ABORT) {
+set_iteration_aborted(true);
+}
+}
+// An ObjectClosure used to support the IterateThroughHeap function
+class IterateThroughHeapObjectClosure: public ObjectClosure {
+private:
+JvmtiTagMap* _tag_map;
+KlassHandle _klass;
+int _heap_filter;
+const jvmtiHeapCallbacks* _callbacks;
+const void* _user_data;
+// accessor functions
+JvmtiTagMap* tag_map() const                     { return _tag_map; }
+int heap_filter() const                          { return _heap_filter; }
+const jvmtiHeapCallbacks* callbacks() const      { return _callbacks; }
+KlassHandle klass() const                        { return _klass; }
+const void* user_data() const                    { return _user_data; }
+// indicates if the iteration has been aborted
+bool _iteration_aborted;
+bool is_iteration_aborted() const                { return _iteration_aborted; }
+// used to check the visit control flags. If the abort flag is set
+// then we set the iteration aborted flag so that the iteration completes
+// without processing any further objects
+bool check_flags_for_abort(jint flags) {
+bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
+if (is_abort) {
+_iteration_aborted = true;
+}
+return is_abort;
+}
+public:
+IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
+KlassHandle klass,
+int heap_filter,
+const jvmtiHeapCallbacks* heap_callbacks,
+const void* user_data) :
+_tag_map(tag_map),
+_klass(klass),
+_heap_filter(heap_filter),
+_callbacks(heap_callbacks),
+_user_data(user_data),
+_iteration_aborted(false)
+{
+}
+void do_object(oop o);
+};
+// invoked for each object in the heap
+void IterateThroughHeapObjectClosure::do_object(oop obj) {
+// check if iteration has been halted
+if (is_iteration_aborted()) return;
+// ignore any objects that aren't visible to profiler
+if (!ServiceUtil::visible_oop(obj)) return;
+// apply class filter
+if (is_filtered_by_klass_filter(obj, klass())) return;
+// prepare for callback
+CallbackWrapper wrapper(tag_map(), obj);
+// check if filtered by the heap filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
+return;
+}
+// for arrays we need the length, otherwise -1
+bool is_array = obj->is_array();
+int len = is_array ? arrayOop(obj)->length() : -1;
+// invoke the object callback (if callback is provided)
+if (callbacks()->heap_iteration_callback != NULL) {
+jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
+jint res = (*cb)(wrapper.klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+(jint)len,
+(void*)user_data());
+if (check_flags_for_abort(res)) return;
+}
+// for objects and classes we report primitive fields if callback provided
+if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
+jint res;
+jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
+if (obj->klass() == SystemDictionary::class_klass()) {
+res = invoke_primitive_field_callback_for_static_fields(&wrapper,
+obj,
+cb,
+(void*)user_data());
+} else {
+res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
+obj,
+cb,
+(void*)user_data());
+}
+if (check_flags_for_abort(res)) return;
+}
+// string callback
+if (!is_array &&
+callbacks()->string_primitive_value_callback != NULL &&
+obj->klass() == SystemDictionary::string_klass()) {
+jint res = invoke_string_value_callback(
+callbacks()->string_primitive_value_callback,
+&wrapper,
+obj,
+(void*)user_data() );
+if (check_flags_for_abort(res)) return;
+}
+// array callback
+if (is_array &&
+callbacks()->array_primitive_value_callback != NULL &&
+obj->is_typeArray()) {
+jint res = invoke_array_primitive_value_callback(
+callbacks()->array_primitive_value_callback,
+&wrapper,
+obj,
+(void*)user_data() );
+if (check_flags_for_abort(res)) return;
+}
+};
+// Deprecated function to iterate over all objects in the heap
+void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
+KlassHandle klass,
+jvmtiHeapObjectCallback heap_object_callback,
+const void* user_data)
+{
+MutexLocker ml(Heap_lock);
+IterateOverHeapObjectClosure blk(this,
+klass,
+object_filter,
+heap_object_callback,
+user_data);
+VM_HeapIterateOperation op(&blk);
+VMThread::execute(&op);
+}
+// Iterates over all objects in the heap
+void JvmtiTagMap::iterate_through_heap(jint heap_filter,
+KlassHandle klass,
+const jvmtiHeapCallbacks* callbacks,
+const void* user_data)
+{
+MutexLocker ml(Heap_lock);
+IterateThroughHeapObjectClosure blk(this,
+klass,
+heap_filter,
+callbacks,
+user_data);
+VM_HeapIterateOperation op(&blk);
+VMThread::execute(&op);
+}
+// support class for get_objects_with_tags
+class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
+private:
+JvmtiEnv* _env;
+jlong* _tags;
+jint _tag_count;
+GrowableArray<jobject>* _object_results;  // collected objects (JNI weak refs)
+GrowableArray<uint64_t>* _tag_results;    // collected tags
+public:
+TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
+_env = env;
+_tags = (jlong*)tags;
+_tag_count = tag_count;
+_object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true);
+_tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true);
+}
+~TagObjectCollector() {
+delete _object_results;
+delete _tag_results;
+}
+// for each tagged object check if the tag value matches
+// - if it matches then we create a JNI local reference to the object
+// and record the reference and tag value.
+//
+void do_entry(JvmtiTagHashmapEntry* entry) {
+for (int i=0; i<_tag_count; i++) {
+if (_tags[i] == entry->tag()) {
+oop o = JNIHandles::resolve(entry->object());
+assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check");
+// the mirror is tagged
+if (o->is_klass()) {
+klassOop k = (klassOop)o;
+o = Klass::cast(k)->java_mirror();
+}
+jobject ref = JNIHandles::make_local(JavaThread::current(), o);
+_object_results->append(ref);
+_tag_results->append((uint64_t)entry->tag());
+}
+}
+}
+// return the results from the collection
+//
+jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
+jvmtiError error;
+int count = _object_results->length();
+assert(count >= 0, "sanity check");
+// if object_result_ptr is not NULL then allocate the result and copy
+// in the object references.
+if (object_result_ptr != NULL) {
+error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
+if (error != JVMTI_ERROR_NONE) {
+return error;
+}
+for (int i=0; i<count; i++) {
+(*object_result_ptr)[i] = _object_results->at(i);
+}
+}
+// if tag_result_ptr is not NULL then allocate the result and copy
+// in the tag values.
+if (tag_result_ptr != NULL) {
+error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
+if (error != JVMTI_ERROR_NONE) {
+if (object_result_ptr != NULL) {
+_env->Deallocate((unsigned char*)object_result_ptr);
+}
+return error;
+}
+for (int i=0; i<count; i++) {
+(*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
+}
+}
+*count_ptr = count;
+return JVMTI_ERROR_NONE;
+}
+};
+// return the list of objects with the specified tags
+jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
+jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
+TagObjectCollector collector(env(), tags, count);
+{
+// iterate over all tagged objects
+MutexLocker ml(lock());
+entry_iterate(&collector);
+}
+return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
+}
+// ObjectMarker is used to support the marking objects when walking the
+// heap.
+//
+// This implementation uses the existing mark bits in an object for
+// marking. Objects that are marked must later have their headers restored.
+// As most objects are unlocked and don't have their identity hash computed
+// we don't have to save their headers. Instead we save the headers that
+// are "interesting". Later when the headers are restored this implementation
+// restores all headers to their initial value and then restores the few
+// objects that had interesting headers.
+//
+// Future work: This implementation currently uses growable arrays to save
+// the oop and header of interesting objects. As an optimization we could
+// use the same technique as the GC and make use of the unused area
+// between top() and end().
+//
+// An ObjectClosure used to restore the mark bits of an object
+class RestoreMarksClosure : public ObjectClosure {
+public:
+void do_object(oop o) {
+if (o != NULL) {
+markOop mark = o->mark();
+if (mark->is_marked()) {
+o->init_mark();
+}
+}
+}
+};
+// ObjectMarker provides the mark and visited functions
+class ObjectMarker : AllStatic {
+private:
+// saved headers
+static GrowableArray<oop>* _saved_oop_stack;
+static GrowableArray<markOop>* _saved_mark_stack;
+public:
+static void init();                       // initialize
+static void done();                       // clean-up
+static inline void mark(oop o);           // mark an object
+static inline bool visited(oop o);        // check if object has been visited
+};
+GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
+GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
+// initialize ObjectMarker - prepares for object marking
+void ObjectMarker::init() {
+assert(Thread::current()->is_VM_thread(), "must be VMThread");
+// prepare heap for iteration
+Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
+// create stacks for interesting headers
+_saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true);
+_saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
+if (UseBiasedLocking) {
+BiasedLocking::preserve_marks();
+}
+}
+// Object marking is done so restore object headers
+void ObjectMarker::done() {
+// iterate over all objects and restore the mark bits to
+// their initial value
+RestoreMarksClosure blk;
+Universe::heap()->object_iterate(&blk);
+// When sharing is enabled we need to restore the headers of the objects
+// in the readwrite space too.
+if (UseSharedSpaces) {
+GenCollectedHeap* gch = GenCollectedHeap::heap();
+CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
+gen->rw_space()->object_iterate(&blk);
+}
+// now restore the interesting headers
+for (int i = 0; i < _saved_oop_stack->length(); i++) {
+oop o = _saved_oop_stack->at(i);
+markOop mark = _saved_mark_stack->at(i);
+o->set_mark(mark);
+}
+if (UseBiasedLocking) {
+BiasedLocking::restore_marks();
+}
+// free the stacks
+delete _saved_oop_stack;
+delete _saved_mark_stack;
+}
+// mark an object
+inline void ObjectMarker::mark(oop o) {
+assert(Universe::heap()->is_in(o), "sanity check");
+assert(!o->mark()->is_marked(), "should only mark an object once");
+// object's mark word
+markOop mark = o->mark();
+if (mark->must_be_preserved(o)) {
+_saved_mark_stack->push(mark);
+_saved_oop_stack->push(o);
+}
+// mark the object
+o->set_mark(markOopDesc::prototype()->set_marked());
+}
+// return true if object is marked
+inline bool ObjectMarker::visited(oop o) {
+return o->mark()->is_marked();
+}
+// Stack allocated class to help ensure that ObjectMarker is used
+// correctly. Constructor initializes ObjectMarker, destructor calls
+// ObjectMarker's done() function to restore object headers.
+class ObjectMarkerController : public StackObj {
+public:
+ObjectMarkerController() {
+ObjectMarker::init();
+}
+~ObjectMarkerController() {
+ObjectMarker::done();
+}
+};
+// helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
+// (not performance critical as only used for roots)
+static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
+switch (kind) {
+case JVMTI_HEAP_REFERENCE_JNI_GLOBAL:   return JVMTI_HEAP_ROOT_JNI_GLOBAL;
+case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
+case JVMTI_HEAP_REFERENCE_MONITOR:      return JVMTI_HEAP_ROOT_MONITOR;
+case JVMTI_HEAP_REFERENCE_STACK_LOCAL:  return JVMTI_HEAP_ROOT_STACK_LOCAL;
+case JVMTI_HEAP_REFERENCE_JNI_LOCAL:    return JVMTI_HEAP_ROOT_JNI_LOCAL;
+case JVMTI_HEAP_REFERENCE_THREAD:       return JVMTI_HEAP_ROOT_THREAD;
+case JVMTI_HEAP_REFERENCE_OTHER:        return JVMTI_HEAP_ROOT_OTHER;
+default: ShouldNotReachHere();          return JVMTI_HEAP_ROOT_OTHER;
+}
+}
+// Base class for all heap walk contexts. The base class maintains a flag
+// to indicate if the context is valid or not.
+class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
+private:
+bool _valid;
+public:
+HeapWalkContext(bool valid)                   { _valid = valid; }
+void invalidate()                             { _valid = false; }
+bool is_valid() const                         { return _valid; }
+};
+// A basic heap walk context for the deprecated heap walking functions.
+// The context for a basic heap walk are the callbacks and fields used by
+// the referrer caching scheme.
+class BasicHeapWalkContext: public HeapWalkContext {
+private:
+jvmtiHeapRootCallback _heap_root_callback;
+jvmtiStackReferenceCallback _stack_ref_callback;
+jvmtiObjectReferenceCallback _object_ref_callback;
+// used for caching
+oop _last_referrer;
+jlong _last_referrer_tag;
+public:
+BasicHeapWalkContext() : HeapWalkContext(false) { }
+BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
+jvmtiStackReferenceCallback stack_ref_callback,
+jvmtiObjectReferenceCallback object_ref_callback) :
+HeapWalkContext(true),
+_heap_root_callback(heap_root_callback),
+_stack_ref_callback(stack_ref_callback),
+_object_ref_callback(object_ref_callback),
+_last_referrer(NULL),
+_last_referrer_tag(0) {
+}
+// accessors
+jvmtiHeapRootCallback heap_root_callback() const         { return _heap_root_callback; }
+jvmtiStackReferenceCallback stack_ref_callback() const   { return _stack_ref_callback; }
+jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback;  }
+oop last_referrer() const               { return _last_referrer; }
+void set_last_referrer(oop referrer)    { _last_referrer = referrer; }
+jlong last_referrer_tag() const         { return _last_referrer_tag; }
+void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
+};
+// The advanced heap walk context for the FollowReferences functions.
+// The context is the callbacks, and the fields used for filtering.
+class AdvancedHeapWalkContext: public HeapWalkContext {
+private:
+jint _heap_filter;
+KlassHandle _klass_filter;
+const jvmtiHeapCallbacks* _heap_callbacks;
+public:
+AdvancedHeapWalkContext() : HeapWalkContext(false) { }
+AdvancedHeapWalkContext(jint heap_filter,
+KlassHandle klass_filter,
+const jvmtiHeapCallbacks* heap_callbacks) :
+HeapWalkContext(true),
+_heap_filter(heap_filter),
+_klass_filter(klass_filter),
+_heap_callbacks(heap_callbacks) {
+}
+// accessors
+jint heap_filter() const         { return _heap_filter; }
+KlassHandle klass_filter() const { return _klass_filter; }
+const jvmtiHeapReferenceCallback heap_reference_callback() const {
+return _heap_callbacks->heap_reference_callback;
+};
+const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
+return _heap_callbacks->primitive_field_callback;
+}
+const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
+return _heap_callbacks->array_primitive_value_callback;
+}
+const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
+return _heap_callbacks->string_primitive_value_callback;
+}
+};
+// The CallbackInvoker is a class with static functions that the heap walk can call
+// into to invoke callbacks. It works in one of two modes. The "basic" mode is
+// used for the deprecated IterateOverReachableObjects functions. The "advanced"
+// mode is for the newer FollowReferences function which supports a lot of
+// additional callbacks.
+class CallbackInvoker : AllStatic {
+private:
+// heap walk styles
+enum { basic, advanced };
+static int _heap_walk_type;
+static bool is_basic_heap_walk()           { return _heap_walk_type == basic; }
+static bool is_advanced_heap_walk()        { return _heap_walk_type == advanced; }
+// context for basic style heap walk
+static BasicHeapWalkContext _basic_context;
+static BasicHeapWalkContext* basic_context() {
+assert(_basic_context.is_valid(), "invalid");
+return &_basic_context;
+}
+// context for advanced style heap walk
+static AdvancedHeapWalkContext _advanced_context;
+static AdvancedHeapWalkContext* advanced_context() {
+assert(_advanced_context.is_valid(), "invalid");
+return &_advanced_context;
+}
+// context needed for all heap walks
+static JvmtiTagMap* _tag_map;
+static const void* _user_data;
+static GrowableArray<oop>* _visit_stack;
+// accessors
+static JvmtiTagMap* tag_map()                        { return _tag_map; }
+static const void* user_data()                       { return _user_data; }
+static GrowableArray<oop>* visit_stack()             { return _visit_stack; }
+// if the object hasn't been visited then push it onto the visit stack
+// so that it will be visited later
+static inline bool check_for_visit(oop obj) {
+if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
+return true;
+}
+// invoke basic style callbacks
+static inline bool invoke_basic_heap_root_callback
+(jvmtiHeapRootKind root_kind, oop obj);
+static inline bool invoke_basic_stack_ref_callback
+(jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
+int slot, oop obj);
+static inline bool invoke_basic_object_reference_callback
+(jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
+// invoke advanced style callbacks
+static inline bool invoke_advanced_heap_root_callback
+(jvmtiHeapReferenceKind ref_kind, oop obj);
+static inline bool invoke_advanced_stack_ref_callback
+(jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
+jmethodID method, jlocation bci, jint slot, oop obj);
+static inline bool invoke_advanced_object_reference_callback
+(jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
+// used to report the value of primitive fields
+static inline bool report_primitive_field
+(jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
+public:
+// initialize for basic mode
+static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
+GrowableArray<oop>* visit_stack,
+const void* user_data,
+BasicHeapWalkContext context);
+// initialize for advanced mode
+static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
+GrowableArray<oop>* visit_stack,
+const void* user_data,
+AdvancedHeapWalkContext context);
+// functions to report roots
+static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
+static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
+jmethodID m, oop o);
+static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
+jmethodID method, jlocation bci, jint slot, oop o);
+// functions to report references
+static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
+static inline bool report_class_reference(oop referrer, oop referree);
+static inline bool report_class_loader_reference(oop referrer, oop referree);
+static inline bool report_signers_reference(oop referrer, oop referree);
+static inline bool report_protection_domain_reference(oop referrer, oop referree);
+static inline bool report_superclass_reference(oop referrer, oop referree);
+static inline bool report_interface_reference(oop referrer, oop referree);
+static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
+static inline bool report_field_reference(oop referrer, oop referree, jint slot);
+static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
+static inline bool report_primitive_array_values(oop array);
+static inline bool report_string_value(oop str);
+static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
+static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
+};
+// statics
+int CallbackInvoker::_heap_walk_type;
+BasicHeapWalkContext CallbackInvoker::_basic_context;
+AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
+JvmtiTagMap* CallbackInvoker::_tag_map;
+const void* CallbackInvoker::_user_data;
+GrowableArray<oop>* CallbackInvoker::_visit_stack;
+// initialize for basic heap walk (IterateOverReachableObjects et al)
+void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
+GrowableArray<oop>* visit_stack,
+const void* user_data,
+BasicHeapWalkContext context) {
+_tag_map = tag_map;
+_visit_stack = visit_stack;
+_user_data = user_data;
+_basic_context = context;
+_advanced_context.invalidate();       // will trigger assertion if used
+_heap_walk_type = basic;
+}
+// initialize for advanced heap walk (FollowReferences)
+void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
+GrowableArray<oop>* visit_stack,
+const void* user_data,
+AdvancedHeapWalkContext context) {
+_tag_map = tag_map;
+_visit_stack = visit_stack;
+_user_data = user_data;
+_advanced_context = context;
+_basic_context.invalidate();      // will trigger assertion if used
+_heap_walk_type = advanced;
+}
+// invoke basic style heap root callback
+inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
+assert(ServiceUtil::visible_oop(obj), "checking");
+// if we heap roots should be reported
+jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
+if (cb == NULL) {
+return check_for_visit(obj);
+}
+CallbackWrapper wrapper(tag_map(), obj);
+jvmtiIterationControl control = (*cb)(root_kind,
+wrapper.klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+(void*)user_data());
+// push root to visit stack when following references
+if (control == JVMTI_ITERATION_CONTINUE &&
+basic_context()->object_ref_callback() != NULL) {
+visit_stack()->push(obj);
+}
+return control != JVMTI_ITERATION_ABORT;
+}
+// invoke basic style stack ref callback
+inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
+jlong thread_tag,
+jint depth,
+jmethodID method,
+jint slot,
+oop obj) {
+assert(ServiceUtil::visible_oop(obj), "checking");
+// if we stack refs should be reported
+jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
+if (cb == NULL) {
+return check_for_visit(obj);
+}
+CallbackWrapper wrapper(tag_map(), obj);
+jvmtiIterationControl control = (*cb)(root_kind,
+wrapper.klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+thread_tag,
+depth,
+method,
+slot,
+(void*)user_data());
+// push root to visit stack when following references
+if (control == JVMTI_ITERATION_CONTINUE &&
+basic_context()->object_ref_callback() != NULL) {
+visit_stack()->push(obj);
+}
+return control != JVMTI_ITERATION_ABORT;
+}
+// invoke basic style object reference callback
+inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
+oop referrer,
+oop referree,
+jint index) {
+assert(ServiceUtil::visible_oop(referrer), "checking");
+assert(ServiceUtil::visible_oop(referree), "checking");
+BasicHeapWalkContext* context = basic_context();
+// callback requires the referrer's tag. If it's the same referrer
+// as the last call then we use the cached value.
+jlong referrer_tag;
+if (referrer == context->last_referrer()) {
+referrer_tag = context->last_referrer_tag();
+} else {
+referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer));
+}
+// do the callback
+CallbackWrapper wrapper(tag_map(), referree);
+jvmtiObjectReferenceCallback cb = context->object_ref_callback();
+jvmtiIterationControl control = (*cb)(ref_kind,
+wrapper.klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+referrer_tag,
+index,
+(void*)user_data());
+// record referrer and referrer tag. For self-references record the
+// tag value from the callback as this might differ from referrer_tag.
+context->set_last_referrer(referrer);
+if (referrer == referree) {
+context->set_last_referrer_tag(*wrapper.obj_tag_p());
+} else {
+context->set_last_referrer_tag(referrer_tag);
+}
+if (control == JVMTI_ITERATION_CONTINUE) {
+return check_for_visit(referree);
+} else {
+return control != JVMTI_ITERATION_ABORT;
+}
+}
+// invoke advanced style heap root callback
+inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
+oop obj) {
+assert(ServiceUtil::visible_oop(obj), "checking");
+AdvancedHeapWalkContext* context = advanced_context();
+// check that callback is provided
+jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
+if (cb == NULL) {
+return check_for_visit(obj);
+}
+// apply class filter
+if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
+return check_for_visit(obj);
+}
+// setup the callback wrapper
+CallbackWrapper wrapper(tag_map(), obj);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return check_for_visit(obj);
+}
+// for arrays we need the length, otherwise -1
+jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
+// invoke the callback
+jint res  = (*cb)(ref_kind,
+NULL, // referrer info
+wrapper.klass_tag(),
+0,    // referrer_class_tag is 0 for heap root
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+NULL, // referrer_tag_p
+len,
+(void*)user_data());
+if (res & JVMTI_VISIT_ABORT) {
+return false;// referrer class tag
+}
+if (res & JVMTI_VISIT_OBJECTS) {
+check_for_visit(obj);
+}
+return true;
+}
+// report a reference from a thread stack to an object
+inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
+jlong thread_tag,
+jlong tid,
+int depth,
+jmethodID method,
+jlocation bci,
+jint slot,
+oop obj) {
+assert(ServiceUtil::visible_oop(obj), "checking");
+AdvancedHeapWalkContext* context = advanced_context();
+// check that callback is provider
+jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
+if (cb == NULL) {
+return check_for_visit(obj);
+}
+// apply class filter
+if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
+return check_for_visit(obj);
+}
+// setup the callback wrapper
+CallbackWrapper wrapper(tag_map(), obj);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return check_for_visit(obj);
+}
+// setup the referrer info
+jvmtiHeapReferenceInfo reference_info;
+reference_info.stack_local.thread_tag = thread_tag;
+reference_info.stack_local.thread_id = tid;
+reference_info.stack_local.depth = depth;
+reference_info.stack_local.method = method;
+reference_info.stack_local.location = bci;
+reference_info.stack_local.slot = slot;
+// for arrays we need the length, otherwise -1
+jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
+// call into the agent
+int res = (*cb)(ref_kind,
+&reference_info,
+wrapper.klass_tag(),
+0,    // referrer_class_tag is 0 for heap root (stack)
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+NULL, // referrer_tag is 0 for root
+len,
+(void*)user_data());
+if (res & JVMTI_VISIT_ABORT) {
+return false;
+}
+if (res & JVMTI_VISIT_OBJECTS) {
+check_for_visit(obj);
+}
+return true;
+}
+// This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
+// only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
+#define REF_INFO_MASK  ((1 << JVMTI_HEAP_REFERENCE_FIELD)         \
+| (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD)  \
+| (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
+| (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
+| (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL)   \
+| (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
+// invoke the object reference callback to report a reference
+inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
+oop referrer,
+oop obj,
+jint index)
+{
+// field index is only valid field in reference_info
+static jvmtiHeapReferenceInfo reference_info = { 0 };
+assert(ServiceUtil::visible_oop(referrer), "checking");
+assert(ServiceUtil::visible_oop(obj), "checking");
+AdvancedHeapWalkContext* context = advanced_context();
+// check that callback is provider
+jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
+if (cb == NULL) {
+return check_for_visit(obj);
+}
+// apply class filter
+if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
+return check_for_visit(obj);
+}
+// setup the callback wrapper
+TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return check_for_visit(obj);
+}
+// field index is only valid field in reference_info
+reference_info.field.index = index;
+// for arrays we need the length, otherwise -1
+jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
+// invoke the callback
+int res = (*cb)(ref_kind,
+(REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
+wrapper.klass_tag(),
+wrapper.referrer_klass_tag(),
+wrapper.obj_size(),
+wrapper.obj_tag_p(),
+wrapper.referrer_tag_p(),
+len,
+(void*)user_data());
+if (res & JVMTI_VISIT_ABORT) {
+return false;
+}
+if (res & JVMTI_VISIT_OBJECTS) {
+check_for_visit(obj);
+}
+return true;
+}
+// report a "simple root"
+inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
+assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
+kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
+assert(ServiceUtil::visible_oop(obj), "checking");
+if (is_basic_heap_walk()) {
+// map to old style root kind
+jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
+return invoke_basic_heap_root_callback(root_kind, obj);
+} else {
+assert(is_advanced_heap_walk(), "wrong heap walk type");
+return invoke_advanced_heap_root_callback(kind, obj);
+}
+}
+// invoke the primitive array values
+inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
+assert(obj->is_typeArray(), "not a primitive array");
+AdvancedHeapWalkContext* context = advanced_context();
+assert(context->array_primitive_value_callback() != NULL, "no callback");
+// apply class filter
+if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
+return true;
+}
+CallbackWrapper wrapper(tag_map(), obj);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return true;
+}
+// invoke the callback
+int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
+&wrapper,
+obj,
+(void*)user_data());
+return (!(res & JVMTI_VISIT_ABORT));
+}
+// invoke the string value callback
+inline bool CallbackInvoker::report_string_value(oop str) {
+assert(str->klass() == SystemDictionary::string_klass(), "not a string");
+AdvancedHeapWalkContext* context = advanced_context();
+assert(context->string_primitive_value_callback() != NULL, "no callback");
+// apply class filter
+if (is_filtered_by_klass_filter(str, context->klass_filter())) {
+return true;
+}
+CallbackWrapper wrapper(tag_map(), str);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return true;
+}
+// invoke the callback
+int res = invoke_string_value_callback(context->string_primitive_value_callback(),
+&wrapper,
+str,
+(void*)user_data());
+return (!(res & JVMTI_VISIT_ABORT));
+}
+// invoke the primitive field callback
+inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
+oop obj,
+jint index,
+address addr,
+char type)
+{
+// for primitive fields only the index will be set
+static jvmtiHeapReferenceInfo reference_info = { 0 };
+AdvancedHeapWalkContext* context = advanced_context();
+assert(context->primitive_field_callback() != NULL, "no callback");
+// apply class filter
+if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
+return true;
+}
+CallbackWrapper wrapper(tag_map(), obj);
+// apply tag filter
+if (is_filtered_by_heap_filter(wrapper.obj_tag(),
+wrapper.klass_tag(),
+context->heap_filter())) {
+return true;
+}
+// the field index in the referrer
+reference_info.field.index = index;
+// map the type
+jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
+// setup the jvalue
+jvalue value;
+copy_to_jvalue(&value, addr, value_type);
+jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
+int res = (*cb)(ref_kind,
+&reference_info,
+wrapper.klass_tag(),
+wrapper.obj_tag_p(),
+value,
+value_type,
+(void*)user_data());
+return (!(res & JVMTI_VISIT_ABORT));
+}
+// instance field
+inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
+jint index,
+address value,
+char type) {
+return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
+obj,
+index,
+value,
+type);
+}
+// static field
+inline bool CallbackInvoker::report_primitive_static_field(oop obj,
+jint index,
+address value,
+char type) {
+return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
+obj,
+index,
+value,
+type);
+}
+// report a JNI local (root object) to the profiler
+inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
+if (is_basic_heap_walk()) {
+return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
+thread_tag,
+depth,
+m,
+-1,
+obj);
+} else {
+return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
+thread_tag, tid,
+depth,
+m,
+(jlocation)-1,
+-1,
+obj);
+}
+}
+// report a local (stack reference, root object)
+inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
+jlong tid,
+jint depth,
+jmethodID method,
+jlocation bci,
+jint slot,
+oop obj) {
+if (is_basic_heap_walk()) {
+return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
+thread_tag,
+depth,
+method,
+slot,
+obj);
+} else {
+return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
+thread_tag,
+tid,
+depth,
+method,
+bci,
+slot,
+obj);
+}
+}
+// report an object referencing a class.
+inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
+}
+}
+// report a class referencing its class loader.
+inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
+}
+}
+// report a class referencing its signers.
+inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
+}
+}
+// report a class referencing its protection domain..
+inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
+}
+}
+// report a class referencing its superclass.
+inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+// Send this to be consistent with past implementation
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
+}
+}
+// report a class referencing one of its interfaces.
+inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
+}
+}
+// report a class referencing one of its static fields.
+inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
+}
+}
+// report an array referencing an element object
+inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
+}
+}
+// report an object referencing an instance field object
+inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
+}
+}
+// report an array referencing an element object
+inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
+if (is_basic_heap_walk()) {
+return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
+} else {
+return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
+}
+}
+// A supporting closure used to process simple roots
+class SimpleRootsClosure : public OopClosure {
+private:
+jvmtiHeapReferenceKind _kind;
+bool _continue;
+jvmtiHeapReferenceKind root_kind()    { return _kind; }
+public:
+void set_kind(jvmtiHeapReferenceKind kind) {
+_kind = kind;
+_continue = true;
+}
+inline bool stopped() {
+return !_continue;
+}
+void do_oop(oop* obj_p) {
+// iteration has terminated
+if (stopped()) {
+return;
+}
+// ignore null or deleted handles
+oop o = *obj_p;
+if (o == NULL || o == JNIHandles::deleted_handle()) {
+return;
+}
+jvmtiHeapReferenceKind kind = root_kind();
+// many roots are Klasses so we use the java mirror
+if (o->is_klass()) {
+klassOop k = (klassOop)o;
+o = Klass::cast(k)->java_mirror();
+} else {
+// SystemDictionary::always_strong_oops_do reports the application
+// class loader as a root. We want this root to be reported as
+// a root kind of "OTHER" rather than "SYSTEM_CLASS".
+if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
+kind = JVMTI_HEAP_REFERENCE_OTHER;
+}
+}
+// some objects are ignored - in the case of simple
+// roots it's mostly symbolOops that we are skipping
+// here.
+if (!ServiceUtil::visible_oop(o)) {
+return;
+}
+// invoke the callback
+_continue = CallbackInvoker::report_simple_root(kind, o);
+}
+};
+// A supporting closure used to process JNI locals
+class JNILocalRootsClosure : public OopClosure {
+private:
+jlong _thread_tag;
+jlong _tid;
+jint _depth;
+jmethodID _method;
+bool _continue;
+public:
+void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
+_thread_tag = thread_tag;
+_tid = tid;
+_depth = depth;
+_method = method;
+_continue = true;
+}
+inline bool stopped() {
+return !_continue;
+}
+void do_oop(oop* obj_p) {
+// iteration has terminated
+if (stopped()) {
+return;
+}
+// ignore null or deleted handles
+oop o = *obj_p;
+if (o == NULL || o == JNIHandles::deleted_handle()) {
+return;
+}
+if (!ServiceUtil::visible_oop(o)) {
+return;
+}
+// invoke the callback
+_continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
+}
+};
+// A VM operation to iterate over objects that are reachable from
+// a set of roots or an initial object.
+//
+// For VM_HeapWalkOperation the set of roots used is :-
+//
+// - All JNI global references
+// - All inflated monitors
+// - All classes loaded by the boot class loader (or all classes
+//     in the event that class unloading is disabled)
+// - All java threads
+// - For each java thread then all locals and JNI local references
+//      on the thread's execution stack
+// - All visible/explainable objects from Universes::oops_do
+//
+class VM_HeapWalkOperation: public VM_Operation {
+private:
+enum {
+initial_visit_stack_size = 4000
+};
+bool _is_advanced_heap_walk;                      // indicates FollowReferences
+JvmtiTagMap* _tag_map;
+Handle _initial_object;
+GrowableArray<oop>* _visit_stack;                 // the visit stack
+bool _collecting_heap_roots;                      // are we collecting roots
+bool _following_object_refs;                      // are we following object references
+bool _reporting_primitive_fields;                 // optional reporting
+bool _reporting_primitive_array_values;
+bool _reporting_string_values;
+GrowableArray<oop>* create_visit_stack() {
+return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true);
+}
+// accessors
+bool is_advanced_heap_walk() const               { return _is_advanced_heap_walk; }
+JvmtiTagMap* tag_map() const                     { return _tag_map; }
+Handle initial_object() const                    { return _initial_object; }
+bool is_following_references() const             { return _following_object_refs; }
+bool is_reporting_primitive_fields()  const      { return _reporting_primitive_fields; }
+bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
+bool is_reporting_string_values() const          { return _reporting_string_values; }
+GrowableArray<oop>* visit_stack() const          { return _visit_stack; }
+// iterate over the various object types
+inline bool iterate_over_array(oop o);
+inline bool iterate_over_type_array(oop o);
+inline bool iterate_over_class(klassOop o);
+inline bool iterate_over_object(oop o);
+// root collection
+inline bool collect_simple_roots();
+inline bool collect_stack_roots();
+inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
+// visit an object
+inline bool visit(oop o);
+public:
+VM_HeapWalkOperation(JvmtiTagMap* tag_map,
+Handle initial_object,
+BasicHeapWalkContext callbacks,
+const void* user_data);
+VM_HeapWalkOperation(JvmtiTagMap* tag_map,
+Handle initial_object,
+AdvancedHeapWalkContext callbacks,
+const void* user_data);
+~VM_HeapWalkOperation();
+VMOp_Type type() const { return VMOp_HeapWalkOperation; }
+void doit();
+};
+VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
+Handle initial_object,
+BasicHeapWalkContext callbacks,
+const void* user_data) {
+_is_advanced_heap_walk = false;
+_tag_map = tag_map;
+_initial_object = initial_object;
+_following_object_refs = (callbacks.object_ref_callback() != NULL);
+_reporting_primitive_fields = false;
+_reporting_primitive_array_values = false;
+_reporting_string_values = false;
+_visit_stack = create_visit_stack();
+CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
+}
+VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
+Handle initial_object,
+AdvancedHeapWalkContext callbacks,
+const void* user_data) {
+_is_advanced_heap_walk = true;
+_tag_map = tag_map;
+_initial_object = initial_object;
+_following_object_refs = true;
+_reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
+_reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
+_reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
+_visit_stack = create_visit_stack();
+CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
+}
+VM_HeapWalkOperation::~VM_HeapWalkOperation() {
+if (_following_object_refs) {
+assert(_visit_stack != NULL, "checking");
+delete _visit_stack;
+_visit_stack = NULL;
+}
+}
+// an array references its class and has a reference to
+// each element in the array
+inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
+objArrayOop array = objArrayOop(o);
+if (array->klass() == Universe::systemObjArrayKlassObj()) {
+// filtered out
+return true;
+}
+// array reference to its class
+oop mirror = objArrayKlass::cast(array->klass())->java_mirror();
+if (!CallbackInvoker::report_class_reference(o, mirror)) {
+return false;
+}
+// iterate over the array and report each reference to a
+// non-null element
+for (int index=0; index<array->length(); index++) {
+oop elem = array->obj_at(index);
+if (elem == NULL) {
+continue;
+}
+// report the array reference o[index] = elem
+if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
+return false;
+}
+}
+return true;
+}
+// a type array references its class
+inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
+klassOop k = o->klass();
+oop mirror = Klass::cast(k)->java_mirror();
+if (!CallbackInvoker::report_class_reference(o, mirror)) {
+return false;
+}
+// report the array contents if required
+if (is_reporting_primitive_array_values()) {
+if (!CallbackInvoker::report_primitive_array_values(o)) {
+return false;
+}
+}
+return true;
+}
+// verify that a static oop field is in range
+static inline bool verify_static_oop(instanceKlass* ik, oop* obj_p) {
+oop* start = ik->start_of_static_fields();
+oop* end = start + ik->static_oop_field_size();
+assert(end >= start, "sanity check");
+if (obj_p >= start && obj_p < end) {
+return true;
+} else {
+return false;
+}
+}
+// a class references its super class, interfaces, class loader, ...
+// and finally its static fields
+inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) {
+int i;
+Klass* klass = klassOop(k)->klass_part();
+if (klass->oop_is_instance()) {
+instanceKlass* ik = instanceKlass::cast(k);
+// ignore the class if it's has been initialized yet
+if (!ik->is_linked()) {
+return true;
+}
+// get the java mirror
+oop mirror = klass->java_mirror();
+// super (only if something more interesting than java.lang.Object)
+klassOop java_super = ik->java_super();
+if (java_super != NULL && java_super != SystemDictionary::object_klass()) {
+oop super = Klass::cast(java_super)->java_mirror();
+if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
+return false;
+}
+}
+// class loader
+oop cl = ik->class_loader();
+if (cl != NULL) {
+if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
+return false;
+}
+}
+// protection domain
+oop pd = ik->protection_domain();
+if (pd != NULL) {
+if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
+return false;
+}
+}
+// signers
+oop signers = ik->signers();
+if (signers != NULL) {
+if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
+return false;
+}
+}
+// references from the constant pool
+{
+const constantPoolOop pool = ik->constants();
+for (int i = 1; i < pool->length(); i++) {
+constantTag tag = pool->tag_at(i).value();
+if (tag.is_string() || tag.is_klass()) {
+oop entry;
+if (tag.is_string()) {
+entry = pool->resolved_string_at(i);
+assert(java_lang_String::is_instance(entry), "must be string");
+} else {
+entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror();
+}
+if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
+return false;
+}
+}
+}
+}
+// interfaces
+// (These will already have been reported as references from the constant pool
+//  but are specified by IterateOverReachableObjects and must be reported).
+objArrayOop interfaces = ik->local_interfaces();
+for (i = 0; i < interfaces->length(); i++) {
+oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror();
+if (interf == NULL) {
+continue;
+}
+if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
+return false;
+}
+}
+// iterate over the static fields
+ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
+for (i=0; i<field_map->field_count(); i++) {
+ClassFieldDescriptor* field = field_map->field_at(i);
+char type = field->field_type();
+if (!is_primitive_field_type(type)) {
+address addr = (address)k + field->field_offset();
+oop* f = (oop*)addr;
+assert(verify_static_oop(ik, f), "sanity check");
+oop fld_o = *f;
+if (fld_o != NULL) {
+int slot = field->field_index();
+if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
+delete field_map;
+return false;
+}
+}
+} else {
+if (is_reporting_primitive_fields()) {
+address addr = (address)k + field->field_offset();
+int slot = field->field_index();
+if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
+delete field_map;
+return false;
+}
+}
+}
+}
+delete field_map;
+return true;
+}
+return true;
+}
+// an object references a class and its instance fields
+// (static fields are ignored here as we report these as
+// references from the class).
+inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
+// reference to the class
+if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) {
+return false;
+}
+// iterate over instance fields
+ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
+for (int i=0; i<field_map->field_count(); i++) {
+ClassFieldDescriptor* field = field_map->field_at(i);
+char type = field->field_type();
+if (!is_primitive_field_type(type)) {
+address addr = (address)o + field->field_offset();
+oop* f = (oop*)addr;
+oop fld_o = *f;
+if (fld_o != NULL) {
+// reflection code may have a reference to a klassOop.
+// - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe
+if (fld_o->is_klass()) {
+klassOop k = (klassOop)fld_o;
+fld_o = Klass::cast(k)->java_mirror();
+}
+int slot = field->field_index();
+if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
+return false;
+}
+}
+} else {
+if (is_reporting_primitive_fields()) {
+// primitive instance field
+address addr = (address)o + field->field_offset();
+int slot = field->field_index();
+if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
+return false;
+}
+}
+}
+}
+// if the object is a java.lang.String
+if (is_reporting_string_values() &&
+o->klass() == SystemDictionary::string_klass()) {
+if (!CallbackInvoker::report_string_value(o)) {
+return false;
+}
+}
+return true;
+}
+// collects all simple (non-stack) roots.
+// if there's a heap root callback provided then the callback is
+// invoked for each simple root.
+// if an object reference callback is provided then all simple
+// roots are pushed onto the marking stack so that they can be
+// processed later
+//
+inline bool VM_HeapWalkOperation::collect_simple_roots() {
+SimpleRootsClosure blk;
+// JNI globals
+blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
+JNIHandles::oops_do(&blk);
+if (blk.stopped()) {
+return false;
+}
+// Preloaded classes and loader from the system dictionary
+blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
+SystemDictionary::always_strong_oops_do(&blk);
+if (blk.stopped()) {
+return false;
+}
+// Inflated monitors
+blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
+ObjectSynchronizer::oops_do(&blk);
+if (blk.stopped()) {
+return false;
+}
+// Threads
+for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
+oop threadObj = thread->threadObj();
+if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
+bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj);
+if (!cont) {
+return false;
+}
+}
+}
+// Other kinds of roots maintained by HotSpot
+// Many of these won't be visible but others (such as instances of important
+// exceptions) will be visible.
+blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
+Universe::oops_do(&blk);
+return true;
+}
+// Walk the stack of a given thread and find all references (locals
+// and JNI calls) and report these as stack references
+inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
+JNILocalRootsClosure* blk)
+{
+oop threadObj = java_thread->threadObj();
+assert(threadObj != NULL, "sanity check");
+// only need to get the thread's tag once per thread
+jlong thread_tag = tag_for(_tag_map, threadObj);
+// also need the thread id
+jlong tid = java_lang_Thread::thread_id(threadObj);
+if (java_thread->has_last_Java_frame()) {
+// vframes are resource allocated
+Thread* current_thread = Thread::current();
+ResourceMark rm(current_thread);
+HandleMark hm(current_thread);
+RegisterMap reg_map(java_thread);
+frame f = java_thread->last_frame();
+vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
+bool is_top_frame = true;
+int depth = 0;
+frame* last_entry_frame = NULL;
+while (vf != NULL) {
+if (vf->is_java_frame()) {
+// java frame (interpreted, compiled, ...)
+javaVFrame *jvf = javaVFrame::cast(vf);
+// the jmethodID
+jmethodID method = jvf->method()->jmethod_id();
+if (!(jvf->method()->is_native())) {
+jlocation bci = (jlocation)jvf->bci();
+StackValueCollection* locals = jvf->locals();
+for (int slot=0; slot<locals->size(); slot++) {
+if (locals->at(slot)->type() == T_OBJECT) {
+oop o = locals->obj_at(slot)();
+if (o == NULL) {
+continue;
+}
+// stack reference
+if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
+bci, slot, o)) {
+return false;
+}
+}
+}
+} else {
+blk->set_context(thread_tag, tid, depth, method);
+if (is_top_frame) {
+// JNI locals for the top frame.
+java_thread->active_handles()->oops_do(blk);
+} else {
+if (last_entry_frame != NULL) {
+// JNI locals for the entry frame
+assert(last_entry_frame->is_entry_frame(), "checking");
+last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
+}
+}
+}
+last_entry_frame = NULL;
+depth++;
+} else {
+// externalVFrame - for an entry frame then we report the JNI locals
+// when we find the corresponding javaVFrame
+frame* fr = vf->frame_pointer();
+assert(fr != NULL, "sanity check");
+if (fr->is_entry_frame()) {
+last_entry_frame = fr;
+}
+}
+vf = vf->sender();
+is_top_frame = false;
+}
+} else {
+// no last java frame but there may be JNI locals
+blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
+java_thread->active_handles()->oops_do(blk);
+}
+return true;
+}
+// collects all stack roots - for each thread it walks the execution
+// stack to find all references and local JNI refs.
+inline bool VM_HeapWalkOperation::collect_stack_roots() {
+JNILocalRootsClosure blk;
+for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
+oop threadObj = thread->threadObj();
+if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
+if (!collect_stack_roots(thread, &blk)) {
+return false;
+}
+}
+}
+return true;
+}
+// visit an object
+// first mark the object as visited
+// second get all the outbound references from this object (in other words, all
+// the objects referenced by this object).
+//
+bool VM_HeapWalkOperation::visit(oop o) {
+// mark object as visited
+assert(!ObjectMarker::visited(o), "can't visit same object more than once");
+ObjectMarker::mark(o);
+// instance
+if (o->is_instance()) {
+if (o->klass() == SystemDictionary::class_klass()) {
+o = klassOop_if_java_lang_Class(o);
+if (o->is_klass()) {
+// a java.lang.Class
+return iterate_over_class(klassOop(o));
+}
+} else {
+return iterate_over_object(o);
+}
+}
+// object array
+if (o->is_objArray()) {
+return iterate_over_array(o);
+}
+// type array
+if (o->is_typeArray()) {
+return iterate_over_type_array(o);
+}
+return true;
+}
+void VM_HeapWalkOperation::doit() {
+ResourceMark rm;
+ObjectMarkerController marker;
+ClassFieldMapCacheMark cm;
+assert(visit_stack()->is_empty(), "visit stack must be empty");
+// the heap walk starts with an initial object or the heap roots
+if (initial_object().is_null()) {
+if (!collect_simple_roots()) return;
+if (!collect_stack_roots()) return;
+} else {
+visit_stack()->push(initial_object()());
+}
+// object references required
+if (is_following_references()) {
+// visit each object until all reachable objects have been
+// visited or the callback asked to terminate the iteration.
+while (!visit_stack()->is_empty()) {
+oop o = visit_stack()->pop();
+if (!ObjectMarker::visited(o)) {
+if (!visit(o)) {
+break;
+}
+}
+}
+}
+}
+// iterate over all objects that are reachable from a set of roots
+void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
+jvmtiStackReferenceCallback stack_ref_callback,
+jvmtiObjectReferenceCallback object_ref_callback,
+const void* user_data) {
+MutexLocker ml(Heap_lock);
+BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
+VM_HeapWalkOperation op(this, Handle(), context, user_data);
+VMThread::execute(&op);
+}
+// iterate over all objects that are reachable from a given object
+void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
+jvmtiObjectReferenceCallback object_ref_callback,
+const void* user_data) {
+oop obj = JNIHandles::resolve(object);
+Handle initial_object(Thread::current(), obj);
+MutexLocker ml(Heap_lock);
+BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
+VM_HeapWalkOperation op(this, initial_object, context, user_data);
+VMThread::execute(&op);
+}
+// follow references from an initial object or the GC roots
+void JvmtiTagMap::follow_references(jint heap_filter,
+KlassHandle klass,
+jobject object,
+const jvmtiHeapCallbacks* callbacks,
+const void* user_data)
+{
+oop obj = JNIHandles::resolve(object);
+Handle initial_object(Thread::current(), obj);
+MutexLocker ml(Heap_lock);
+AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
+VM_HeapWalkOperation op(this, initial_object, context, user_data);
+VMThread::execute(&op);
+}
+// called post-GC
+// - for each JVMTI environment with an object tag map, call its rehash
+// function to re-sync with the new object locations.
+void JvmtiTagMap::gc_epilogue(bool full) {
+assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
+if (JvmtiEnv::environments_might_exist()) {
+// re-obtain the memory region for the young generation (might
+// changed due to adaptive resizing policy)
+get_young_generation();
+JvmtiEnvIterator it;
+for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
+JvmtiTagMap* tag_map = env->tag_map();
+if (tag_map != NULL && !tag_map->is_empty()) {
+TraceTime t(full ? "JVMTI Full Rehash " : "JVMTI Rehash ", TraceJVMTIObjectTagging);
+if (full) {
+tag_map->rehash(0, n_hashmaps);
+} else {
+tag_map->rehash(0, 0);        // tag map for young gen only
+}
+}
+}
+}
+}
+// CMS has completed referencing processing so we may have JNI weak refs
+// to objects in the CMS generation that have been GC'ed.
+void JvmtiTagMap::cms_ref_processing_epilogue() {
+assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
+assert(UseConcMarkSweepGC, "should only be used with CMS");
+if (JvmtiEnv::environments_might_exist()) {
+JvmtiEnvIterator it;
+for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
+JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
+if (tag_map != NULL && !tag_map->is_empty()) {
+TraceTime t("JVMTI Rehash (CMS) ", TraceJVMTIObjectTagging);
+tag_map->rehash(1, n_hashmaps);    // assume CMS not used in young gen
+}
+}
+}
+}
+// For each entry in the hashmaps 'start' to 'end' :
+//
+// 1. resolve the JNI weak reference
+//
+// 2. If it resolves to NULL it means the object has been freed so the entry
+//    is removed, the weak reference destroyed, and the object free event is
+//    posted (if enabled).
+//
+// 3. If the weak reference resolves to an object then we re-hash the object
+//    to see if it has moved or has been promoted (from the young to the old
+//    generation for example).
+//
+void JvmtiTagMap::rehash(int start, int end) {
+// does this environment have the OBJECT_FREE event enabled
+bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
+// counters used for trace message
+int freed = 0;
+int moved = 0;
+int promoted = 0;
+// we assume there are two hashmaps - one for the young generation
+// and the other for all other spaces.
+assert(n_hashmaps == 2, "not implemented");
+JvmtiTagHashmap* young_hashmap = _hashmap[0];
+JvmtiTagHashmap* other_hashmap = _hashmap[1];
+// reenable sizing (if disabled)
+young_hashmap->set_resizing_enabled(true);
+other_hashmap->set_resizing_enabled(true);
+// when re-hashing the hashmap corresponding to the young generation we
+// collect the entries corresponding to objects that have been promoted.
+JvmtiTagHashmapEntry* promoted_entries = NULL;
+if (end >= n_hashmaps) {
+end = n_hashmaps - 1;
+}
+for (int i=start; i <= end; i++) {
+JvmtiTagHashmap* hashmap = _hashmap[i];
+// if the hashmap is empty then we can skip it
+if (hashmap->_entry_count == 0) {
+continue;
+}
+// now iterate through each entry in the table
+JvmtiTagHashmapEntry** table = hashmap->table();
+int size = hashmap->size();
+for (int pos=0; pos<size; pos++) {
+JvmtiTagHashmapEntry* entry = table[pos];
+JvmtiTagHashmapEntry* prev = NULL;
+while (entry != NULL) {
+JvmtiTagHashmapEntry* next = entry->next();
+jweak ref = entry->object();
+oop oop = JNIHandles::resolve(ref);
+// has object been GC'ed
+if (oop == NULL) {
+// grab the tag
+jlong tag = entry->tag();
+guarantee(tag != 0, "checking");
+// remove GC'ed entry from hashmap and return the
+// entry to the free list
+hashmap->remove(prev, pos, entry);
+destroy_entry(entry);
+// destroy the weak ref
+JNIHandles::destroy_weak_global(ref);
+// post the event to the profiler
+if (post_object_free) {
+JvmtiExport::post_object_free(env(), tag);
+}
+freed++;
+entry = next;
+continue;
+}
+// if this is the young hashmap then the object is either promoted
+// or moved.
+// if this is the other hashmap then the object is moved.
+bool same_gen;
+if (i == 0) {
+assert(hashmap == young_hashmap, "checking");
+same_gen = is_in_young(oop);
+} else {
+same_gen = true;
+}
+if (same_gen) {
+// if the object has moved then re-hash it and move its
+// entry to its new location.
+unsigned int new_pos = JvmtiTagHashmap::hash(oop, size);
+if (new_pos != (unsigned int)pos) {
+if (prev == NULL) {
+table[pos] = next;
+} else {
+prev->set_next(next);
+}
+entry->set_next(table[new_pos]);
+table[new_pos] = entry;
+moved++;
+} else {
+// object didn't move
+prev = entry;
+}
+} else {
+// object has been promoted so remove the entry from the
+// young hashmap
+assert(hashmap == young_hashmap, "checking");
+hashmap->remove(prev, pos, entry);
+// move the entry to the promoted list
+entry->set_next(promoted_entries);
+promoted_entries = entry;
+}
+entry = next;
+}
+}
+}
+// add the entries, corresponding to the promoted objects, to the
+// other hashmap.
+JvmtiTagHashmapEntry* entry = promoted_entries;
+while (entry != NULL) {
+oop o = JNIHandles::resolve(entry->object());
+assert(hashmap_for(o) == other_hashmap, "checking");
+JvmtiTagHashmapEntry* next = entry->next();
+other_hashmap->add(o, entry);
+entry = next;
+promoted++;
+}
+// stats
+if (TraceJVMTIObjectTagging) {
+int total_moves = promoted + moved;
+int post_total = 0;
+for (int i=0; i<n_hashmaps; i++) {
+post_total += _hashmap[i]->_entry_count;
+}
+int pre_total = post_total + freed;
+tty->print("(%d->%d, %d freed, %d promoted, %d total moves)",
+pre_total, post_total, freed, promoted, total_moves);
+}
+}

Mercurial > hg > truffle

comparison src/share/vm/prims/jvmtiTagMap.cpp @ 0:a61af66fc99e jdk7-b24