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* Copyright (C) 2008 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef ART_SRC_HEAP_H_
#define ART_SRC_HEAP_H_
#include <string>
#include <vector>
#include "card_table.h"
#include "globals.h"
#include "gtest/gtest.h"
#include "heap_bitmap.h"
#include "mutex.h"
#include "offsets.h"
namespace art {
class AllocSpace;
class Class;
class ImageSpace;
class Object;
class Space;
class Thread;
class HeapBitmap;
class SpaceTest;
class Heap {
static const size_t kInitialSize = 2 * MB;
static const size_t kMaximumSize = 32 * MB;
typedef void (RootVisitor)(const Object* root, void* arg);
typedef bool (IsMarkedTester)(const Object* object, void* arg);
// Create a heap with the requested sizes. The possible empty
// image_file_names names specify Spaces to load based on
// ImageWriter output.
explicit Heap(size_t starting_size, size_t growth_limit, size_t capacity,
const std::string& image_file_name);
// Allocates and initializes storage for an object instance.
Object* AllocObject(Class* klass, size_t num_bytes);
// Check sanity of given reference. Requires the heap lock.
void VerifyObject(const Object* o);
void VerifyObject(const Object*) {}
// Check sanity of all live references. Requires the heap lock.
void VerifyHeap();
// A weaker test than IsLiveObject or VerifyObject that doesn't require the heap lock,
// and doesn't abort on error, allowing the caller to report more
// meaningful diagnostics.
bool IsHeapAddress(const Object* obj);
// Returns true if 'obj' is a live heap object, false otherwise (including for invalid addresses).
// Requires the heap lock to be held.
bool IsLiveObjectLocked(const Object* obj);
// Initiates an explicit garbage collection.
void CollectGarbage(bool clear_soft_references);
// Implements java.lang.Runtime.maxMemory.
int64_t GetMaxMemory();
// Implements java.lang.Runtime.totalMemory.
int64_t GetTotalMemory();
// Implements java.lang.Runtime.freeMemory.
int64_t GetFreeMemory();
// Implements VMDebug.countInstancesOfClass.
int64_t CountInstances(Class* c, bool count_assignable);
// Removes the growth limit on the alloc space so it may grow to its maximum capacity. Used to
// implement dalvik.system.VMRuntime.clearGrowthLimit.
void ClearGrowthLimit();
// Target ideal heap utilization ratio, implements
// dalvik.system.VMRuntime.getTargetHeapUtilization.
float GetTargetHeapUtilization() {
return target_utilization_;
// Set target ideal heap utilization ratio, implements
// dalvik.system.VMRuntime.setTargetHeapUtilization.
void SetTargetHeapUtilization(float target) {
DCHECK_GT(target, 0.0f); // asserted in Java code
DCHECK_LT(target, 1.0f);
target_utilization_ = target;
// For the alloc space, sets the maximum number of bytes that the heap is allowed to allocate
// from the system. Doesn't allow the space to exceed its growth limit.
void SetIdealFootprint(size_t max_allowed_footprint);
// Blocks the caller until the garbage collector becomes idle.
void WaitForConcurrentGcToComplete();
pid_t GetLockOwner(); // For SignalCatcher.
void Lock();
void Unlock();
void AssertLockHeld() {
void AssertLockNotHeld() {
const std::vector<Space*>& GetSpaces() {
return spaces_;
HeapBitmap* GetLiveBits() {
return live_bitmap_;
HeapBitmap* GetMarkBits() {
return mark_bitmap_;
void SetWellKnownClasses(Class* java_lang_ref_FinalizerReference,
Class* java_lang_ref_ReferenceQueue);
void SetReferenceOffsets(MemberOffset reference_referent_offset,
MemberOffset reference_queue_offset,
MemberOffset reference_queueNext_offset,
MemberOffset reference_pendingNext_offset,
MemberOffset finalizer_reference_zombie_offset);
Object* GetReferenceReferent(Object* reference);
void ClearReferenceReferent(Object* reference);
// Returns true if the reference object has not yet been enqueued.
bool IsEnqueuable(const Object* ref);
void EnqueueReference(Object* ref, Object** list);
void EnqueuePendingReference(Object* ref, Object** list);
Object* DequeuePendingReference(Object** list);
MemberOffset GetReferencePendingNextOffset() {
DCHECK_NE(reference_pendingNext_offset_.Uint32Value(), 0U);
return reference_pendingNext_offset_;
MemberOffset GetFinalizerReferenceZombieOffset() {
DCHECK_NE(finalizer_reference_zombie_offset_.Uint32Value(), 0U);
return finalizer_reference_zombie_offset_;
void EnableObjectValidation() {
verify_objects_ = true;
void DisableObjectValidation() {
verify_objects_ = false;
// Callers must hold the heap lock.
void RecordFreeLocked(size_t freed_objects, size_t freed_bytes);
// Must be called if a field of an Object in the heap changes, and before any GC safe-point.
// The call is not needed if NULL is stored in the field.
void WriteBarrierField(const Object* dst, MemberOffset /*offset*/, const Object* /*new_value*/) {
if (!card_marking_disabled_) {
// Write barrier for array operations that update many field positions
void WriteBarrierArray(const Object* dst, int /*start_offset*/, size_t /*length TODO: element_count or byte_count?*/) {
if (UNLIKELY(!card_marking_disabled_)) {
CardTable* GetCardTable() {
return card_table_;
void DisableCardMarking() {
// TODO: we shouldn't need to disable card marking, this is here to help the image_writer
card_marking_disabled_ = true;
void AddFinalizerReference(Thread* self, Object* object);
size_t GetBytesAllocated() { return num_bytes_allocated_; }
size_t GetObjectsAllocated() { return num_objects_allocated_; }
ImageSpace* GetImageSpace() {
CHECK(image_space_ != NULL);
return image_space_;
AllocSpace* GetAllocSpace() {
CHECK(alloc_space_ != NULL);
return alloc_space_;
// Allocates uninitialized storage.
Object* AllocateLocked(size_t num_bytes);
Object* AllocateLocked(AllocSpace* space, size_t num_bytes);
// Pushes a list of cleared references out to the managed heap.
void EnqueueClearedReferences(Object** cleared_references);
void RequestHeapTrim();
void RecordAllocationLocked(AllocSpace* space, const Object* object);
void RecordImageAllocations(Space* space);
void CollectGarbageInternal(bool clear_soft_references);
// Given the current contents of the alloc space, increase the allowed heap footprint to match
// the target utilization ratio. This should only be called immediately after a full garbage
// collection.
void GrowForUtilization();
void AddSpace(Space* space);
void VerifyObjectLocked(const Object *obj);
void VerifyHeapLocked();
static void VerificationCallback(Object* obj, void* arg);
Mutex* lock_;
std::vector<Space*> spaces_;
ImageSpace* image_space_;
// default Space for allocations
AllocSpace* alloc_space_;
HeapBitmap* mark_bitmap_;
HeapBitmap* live_bitmap_;
CardTable* card_table_;
// Used by the image writer to disable card marking on copied objects
// TODO: remove
bool card_marking_disabled_;
// True while the garbage collector is running.
bool is_gc_running_;
// Number of bytes allocated. Adjusted after each allocation and free.
size_t num_bytes_allocated_;
// Number of objects allocated. Adjusted after each allocation and free.
size_t num_objects_allocated_;
Class* java_lang_ref_FinalizerReference_;
Class* java_lang_ref_ReferenceQueue_;
// offset of java.lang.ref.Reference.referent
MemberOffset reference_referent_offset_;
// offset of java.lang.ref.Reference.queue
MemberOffset reference_queue_offset_;
// offset of java.lang.ref.Reference.queueNext
MemberOffset reference_queueNext_offset_;
// offset of java.lang.ref.Reference.pendingNext
MemberOffset reference_pendingNext_offset_;
// offset of java.lang.ref.FinalizerReference.zombie
MemberOffset finalizer_reference_zombie_offset_;
// Target ideal heap utilization ratio
float target_utilization_;
bool verify_objects_;
FRIEND_TEST(SpaceTest, AllocAndFree);
FRIEND_TEST(SpaceTest, AllocAndFreeList);
friend class SpaceTest;
} // namespace art
#endif // ART_SRC_HEAP_H_