jdk-sandbox: comparison hotspot/src/share/vm/prims/jvmtiTagMap.cpp

equal deleted inserted replaced

-:e71bad345f3a
+:08aadd7aa3ee
 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
 #endif
 // JvmtiTagHashmapEntry
 //
-// Each entry encapsulates a JNI weak reference to the tagged object
+// Each entry encapsulates a reference to the tagged object
 // and the tag value. In addition an entry includes a next pointer which
 // is used to chain entries together.
 class JvmtiTagHashmapEntry : public CHeapObj {
 private:
 friend class JvmtiTagMap;
-jweak _object;                        // JNI weak ref to tagged object
+oop _object;                          // tagged object
 jlong _tag;                           // the tag
 JvmtiTagHashmapEntry* _next;          // next on the list
-inline void init(jweak object, jlong tag) {
+inline void init(oop object, jlong tag) {
 _object = object;
 _tag = tag;
 _next = NULL;
 }
 // constructor
-JvmtiTagHashmapEntry(jweak object, jlong tag)         { init(object, tag); }
+JvmtiTagHashmapEntry(oop object, jlong tag)         { init(object, tag); }
 public:
 // accessor methods
-inline jweak object() const                           { return _object; }
+inline oop object() const                           { return _object; }
-inline jlong tag() const                              { return _tag; }
+inline oop* object_addr()                           { return &_object; }
+inline jlong tag() const                            { return _tag; }
 inline void set_tag(jlong tag) {
 assert(tag != 0, "can't be zero");
 _tag = tag;
 }
 // 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
+// the object, or oop. The "value" is the tag value.
-// 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
 // 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());
+oop key = entry->object();
 assert(key != NULL, "jni weak reference cleared!!");
 unsigned int h = hash(key, new_size);
 JvmtiTagHashmapEntry* anchor = new_table[h];
 if (anchor == NULL) {
 new_table[h] = entry;
 // 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());
+if (entry->object() == key) {
-assert(orig_key != NULL, "jni weak reference cleared!!");
+return entry;
-if (key == orig_key) {
-break;
 }
 entry = entry->next();
 }
-return entry;
+return NULL;
 }
 // add a new entry to hashmap
 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
 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());
+if (key == entry->object()) {
-assert(orig_key != NULL, "jni weak reference cleared!!");
-if (key == orig_key) {
 break;
 }
 prev = entry;
 entry = entry->next();
 }
 _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() {
-CollectedHeap* ch = Universe::heap();
-switch (ch->kind()) {
-case (CollectedHeap::GenCollectedHeap): {
-_young_gen = ((GenCollectedHeap*)ch)->get_gen(0)->reserved();
-break;
-}
-#ifndef SERIALGC
-case (CollectedHeap::ParallelScavengeHeap): {
-_young_gen = ((ParallelScavengeHeap*)ch)->young_gen()->reserved();
-break;
-}
-case (CollectedHeap::G1CollectedHeap): {
-// Until a more satisfactory solution is implemented, all
-// oops in the tag map will require rehash at each gc.
-// This is a correct, if extremely inefficient solution.
-// See RFE 6621729 for related commentary.
-_young_gen = ch->reserved_region();
-break;
-}
-#endif  // !SERIALGC
-default:
-ShouldNotReachHere();
-}
-}
-// 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
+_hashmap = new JvmtiTagHashmap();
-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);
 }
 // 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
+JvmtiTagHashmapEntry** table = _hashmap->table();
-for (int i=0; i<n_hashmaps; i++) {
+for (int j = 0; j < _hashmap->size(); j++) {
-JvmtiTagHashmap* hashmap = _hashmap[i];
+JvmtiTagHashmapEntry* entry = table[j];
-JvmtiTagHashmapEntry** table = hashmap->table();
+while (entry != NULL) {
-for (int j=0; j<hashmap->size(); j++) {
+JvmtiTagHashmapEntry* next = entry->next();
-JvmtiTagHashmapEntry *entry = table[j];
+delete entry;
-while (entry != NULL) {
+entry = next;
-JvmtiTagHashmapEntry* next = entry->next();
+}
-jweak ref = entry->object();
+}
-JNIHandles::destroy_weak_global(ref);
-delete entry;
+// finally destroy the hashmap
-entry = next;
+delete _hashmap;
-}
+_hashmap = NULL;
-}
-// 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;
 }
+_free_entries = NULL;
 }
 // create a hashmap entry
 // - if there's an entry on the (per-environment) free list then this
 // is returned. Otherwise an new entry is allocated.
-JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) {
+JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
 JvmtiTagHashmapEntry* entry;
 if (_free_entries == NULL) {
 entry = new JvmtiTagHashmapEntry(ref, tag);
 } else {
 }
 // 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();
+JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
 if (tag_map == NULL) {
 MutexLocker mu(JvmtiThreadState_lock);
-tag_map = ((JvmtiEnvBase *)env)->tag_map();
+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++) {
+hashmap()->entry_iterate(closure);
-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()->entry_count() == 0;
-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);
+JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
 if (entry == NULL) {
 return 0;
 } else {
 return entry->tag();
 }
 // object size
 _obj_size = _o->size() * wordSize;
 // record the context
 _tag_map = tag_map;
-_hashmap = tag_map->hashmap_for(_o);
+_hashmap = tag_map->hashmap();
 _entry = _hashmap->find(_o);
 // get object tag
 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
 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;
+entry = tag_map()->create_entry(o, obj_tag);
-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);
 }
 }
 _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_hashmap = tag_map->hashmap();
 _referrer_entry = _referrer_hashmap->find(_referrer);
 // get object tag
 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
 _referrer_tag_p = &_referrer_obj_tag;
 // 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
+// tag map will be a hot lock.
-// 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);
+JvmtiTagHashmap* hashmap = _hashmap;
 JvmtiTagHashmapEntry* entry = hashmap->find(o);
 // if the object is not already tagged then we tag it
 if (entry == NULL) {
 if (tag != 0) {
-HandleMark hm;
+entry = create_entry(o, tag);
-Handle h(o);
+hashmap->add(o, entry);
-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);
 }
 }
 }
 // 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());
+oop o = entry->object();
-assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check");
+assert(o != NULL, "sanity check");
 // the mirror is tagged
 if (o->is_klass()) {
 klassOop k = (klassOop)o;
 o = Klass::cast(k)->java_mirror();
 VM_HeapWalkOperation op(this, initial_object, context, user_data);
 VMThread::execute(&op);
 }
-// called post-GC
+void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
-// - for each JVMTI environment with an object tag map, call its rehash
+assert(SafepointSynchronize::is_at_safepoint(),
-// function to re-sync with the new object locations.
+"must be executed at a safepoint");
-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);
+tag_map->do_weak_oops(is_alive, f);
-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
+void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
-// 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;
+JvmtiTagHashmap* hashmap = this->hashmap();
-// 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);
+hashmap->set_resizing_enabled(true);
-other_hashmap->set_resizing_enabled(true);
+// if the hashmap is empty then we can skip it
-// when re-hashing the hashmap corresponding to the young generation we
+if (hashmap->_entry_count == 0) {
-// collect the entries corresponding to objects that have been promoted.
+return;
-JvmtiTagHashmapEntry* promoted_entries = NULL;
+}
-if (end >= n_hashmaps) {
+// now iterate through each entry in the table
-end = n_hashmaps - 1;
-}
+JvmtiTagHashmapEntry** table = hashmap->table();
+int size = hashmap->size();
-for (int i=start; i <= end; i++) {
-JvmtiTagHashmap* hashmap = _hashmap[i];
+JvmtiTagHashmapEntry* delayed_add = NULL;
-// if the hashmap is empty then we can skip it
+for (int pos = 0; pos < size; ++pos) {
-if (hashmap->_entry_count == 0) {
+JvmtiTagHashmapEntry* entry = table[pos];
-continue;
+JvmtiTagHashmapEntry* prev = NULL;
-}
+while (entry != NULL) {
-// now iterate through each entry in the table
+JvmtiTagHashmapEntry* next = entry->next();
-JvmtiTagHashmapEntry** table = hashmap->table();
+oop* obj = entry->object_addr();
-int size = hashmap->size();
+// has object been GC'ed
-for (int pos=0; pos<size; pos++) {
+if (!is_alive->do_object_b(entry->object())) {
-JvmtiTagHashmapEntry* entry = table[pos];
+// grab the tag
-JvmtiTagHashmapEntry* prev = NULL;
+jlong tag = entry->tag();
+guarantee(tag != 0, "checking");
-while (entry != NULL) {
-JvmtiTagHashmapEntry* next = entry->next();
+// remove GC'ed entry from hashmap and return the
+// entry to the free list
-jweak ref = entry->object();
+hashmap->remove(prev, pos, entry);
-oop oop = JNIHandles::resolve(ref);
+destroy_entry(entry);
-// has object been GC'ed
+// post the event to the profiler
-if (oop == NULL) {
+if (post_object_free) {
-// grab the tag
+JvmtiExport::post_object_free(env(), tag);
-jlong tag = entry->tag();
+}
-guarantee(tag != 0, "checking");
+++freed;
-// remove GC'ed entry from hashmap and return the
+} else {
-// entry to the free list
+f->do_oop(entry->object_addr());
-hashmap->remove(prev, pos, entry);
+oop new_oop = entry->object();
-destroy_entry(entry);
+// if the object has moved then re-hash it and move its
-// destroy the weak ref
+// entry to its new location.
-JNIHandles::destroy_weak_global(ref);
+unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
+if (new_pos != (unsigned int)pos) {
-// post the event to the profiler
+if (prev == NULL) {
-if (post_object_free) {
+table[pos] = next;
-JvmtiExport::post_object_free(env(), tag);
+} else {
+prev->set_next(next);
 }
+if (new_pos < (unsigned int)pos) {
-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
+// Delay adding this entry to it's new position as we'd end up
-prev = entry;
+// hitting it again during this iteration.
+entry->set_next(delayed_add);
+delayed_add = entry;
 }
+moved++;
 } else {
-// object has been promoted so remove the entry from the
+// object didn't move
-// young hashmap
+prev = entry;
-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;
 }
-}
-}
+entry = next;
+}
+}
-// add the entries, corresponding to the promoted objects, to the
-// other hashmap.
+// Re-add all the entries which were kept aside
-JvmtiTagHashmapEntry* entry = promoted_entries;
+while (delayed_add != NULL) {
-while (entry != NULL) {
+JvmtiTagHashmapEntry* next = delayed_add->next();
-oop o = JNIHandles::resolve(entry->object());
+unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
-assert(hashmap_for(o) == other_hashmap, "checking");
+delayed_add->set_next(table[pos]);
-JvmtiTagHashmapEntry* next = entry->next();
+table[pos] = delayed_add;
-other_hashmap->add(o, entry);
+delayed_add = next;
-entry = next;
-promoted++;
 }
 // stats
 if (TraceJVMTIObjectTagging) {
-int total_moves = promoted + moved;
+int post_total = hashmap->_entry_count;
-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)",
+tty->print_cr("(%d->%d, %d freed, %d total moves)",
-pre_total, post_total, freed, promoted, total_moves);
+pre_total, post_total, freed, moved);
 }
 }

changeset 7896	08aadd7aa3ee
parent 7397	5b173b4ca846
child 7916	84e5b29decb0