< prev index next > src/hotspot/share/prims/jvmtiTagMap.cpp
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#include "runtime/thread.inline.hpp"
#include "runtime/threadSMR.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vmOperations.hpp"
+ #include "utilities/objectBitSet.inline.hpp"
#include "utilities/macros.hpp"
+ typedef ObjectBitSet<mtServiceability> JVMTIBitSet;
+
bool JvmtiTagMap::_has_object_free_events = false;
// create a JvmtiTagMap
JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
_env(env),
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) {
- markWord 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<markWord>* _saved_mark_stack;
- static bool _needs_reset; // do we need to reset mark bits?
-
- public:
- static void init(); // initialize
- static void done(); // clean-up
-
- static inline void mark(oop o); // mark an object
- static inline bool visited(oop o); // check if object has been visited
-
- static inline bool needs_reset() { return _needs_reset; }
- static inline void set_needs_reset(bool v) { _needs_reset = v; }
- };
-
- GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
- GrowableArray<markWord>* ObjectMarker::_saved_mark_stack = NULL;
- bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
-
- // initialize ObjectMarker - prepares for object marking
- void ObjectMarker::init() {
- assert(Thread::current()->is_VM_thread(), "must be VMThread");
- assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
-
- // 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, mtServiceability) GrowableArray<markWord>(4000, mtServiceability);
- _saved_oop_stack = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<oop>(4000, mtServiceability);
-
- if (UseBiasedLocking) {
- BiasedLocking::preserve_marks();
- }
- }
-
- // Object marking is done so restore object headers
- void ObjectMarker::done() {
- // iterate over all objects and restore the mark bits to
- // their initial value
- RestoreMarksClosure blk;
- if (needs_reset()) {
- Universe::heap()->object_iterate(&blk);
- } else {
- // We don't need to reset mark bits on this call, but reset the
- // flag to the default for the next call.
- set_needs_reset(true);
- }
-
- // now restore the interesting headers
- for (int i = 0; i < _saved_oop_stack->length(); i++) {
- oop o = _saved_oop_stack->at(i);
- markWord 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
- markWord mark = o->mark();
-
- if (o->mark_must_be_preserved(mark)) {
- _saved_mark_stack->push(mark);
- _saved_oop_stack->push(o);
- }
-
- // mark the object
- o->set_mark(markWord::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;
// context needed for all heap walks
static JvmtiTagMap* _tag_map;
static const void* _user_data;
static GrowableArray<oop>* _visit_stack;
+ static JVMTIBitSet* _bitset;
// 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);
+ if (!_bitset->is_marked(obj)) visit_stack()->push(obj);
return true;
}
// invoke basic style callbacks
static inline bool invoke_basic_heap_root_callback
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);
+ BasicHeapWalkContext context,
+ JVMTIBitSet* bitset);
// initialize for advanced mode
static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
GrowableArray<oop>* visit_stack,
const void* user_data,
- AdvancedHeapWalkContext context);
+ AdvancedHeapWalkContext context,
+ JVMTIBitSet* bitset);
// 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);
BasicHeapWalkContext CallbackInvoker::_basic_context;
AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
JvmtiTagMap* CallbackInvoker::_tag_map;
const void* CallbackInvoker::_user_data;
GrowableArray<oop>* CallbackInvoker::_visit_stack;
+ JVMTIBitSet* CallbackInvoker::_bitset;
// 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) {
+ BasicHeapWalkContext context,
+ JVMTIBitSet* bitset) {
_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;
+ _bitset = bitset;
}
// 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) {
+ AdvancedHeapWalkContext context,
+ JVMTIBitSet* bitset) {
_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;
+ _bitset = bitset;
}
// invoke basic style heap root callback
inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
bool _is_advanced_heap_walk; // indicates FollowReferences
JvmtiTagMap* _tag_map;
Handle _initial_object;
GrowableArray<oop>* _visit_stack; // the visit stack
+ JVMTIBitSet _bitset;
+
// Dead object tags in JvmtiTagMap
GrowableArray<jlong>* _dead_objects;
bool _following_object_refs; // are we following object references
_reporting_string_values = false;
_visit_stack = create_visit_stack();
_dead_objects = objects;
- CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
+ CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks, &_bitset);
}
VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
Handle initial_object,
AdvancedHeapWalkContext callbacks,
_reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
_reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
_visit_stack = create_visit_stack();
_dead_objects = objects;
- CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
+ CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks, &_bitset);
}
VM_HeapWalkOperation::~VM_HeapWalkOperation() {
if (_following_object_refs) {
assert(_visit_stack != NULL, "checking");
// 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);
+ assert(!_bitset.is_marked(o), "can't visit same object more than once");
+ _bitset.mark_obj(o);
// instance
if (o->is_instance()) {
if (o->klass() == vmClasses::Class_klass()) {
if (!java_lang_Class::is_primitive(o)) {
return true;
}
void VM_HeapWalkOperation::doit() {
ResourceMark rm;
- ObjectMarkerController marker;
ClassFieldMapCacheMark cm;
JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
assert(visit_stack()->is_empty(), "visit stack must be empty");
// the heap walk starts with an initial object or the heap roots
if (initial_object().is_null()) {
- // If either collect_stack_roots() or collect_simple_roots()
- // returns false at this point, then there are no mark bits
- // to reset.
- ObjectMarker::set_needs_reset(false);
-
- // Calling collect_stack_roots() before collect_simple_roots()
// can result in a big performance boost for an agent that is
// focused on analyzing references in the thread stacks.
if (!collect_stack_roots()) return;
if (!collect_simple_roots()) return;
-
- // no early return so enable heap traversal to reset the mark bits
- ObjectMarker::set_needs_reset(true);
} else {
visit_stack()->push(initial_object()());
}
// object references required
// 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 (!_bitset.is_marked(o)) {
if (!visit(o)) {
break;
}
}
}
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