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LeafOS / LeafOS-Project / android_art / c210ab55bcebda93f4e21d6df6e1dca5a5e152c5 / . / runtime / gc / heap.h
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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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_GC_HEAP_H_
#define ART_RUNTIME_GC_HEAP_H_
#include <android-base/logging.h>
#include <iosfwd>
#include <string>
#include <unordered_set>
#include <vector>
#include "allocator_type.h"
#include "base/atomic.h"
#include "base/histogram.h"
#include "base/macros.h"
#include "base/mutex.h"
#include "base/os.h"
#include "base/runtime_debug.h"
#include "base/safe_map.h"
#include "base/time_utils.h"
#include "gc/collector/gc_type.h"
#include "gc/collector/iteration.h"
#include "gc/collector/mark_compact.h"
#include "gc/collector_type.h"
#include "gc/gc_cause.h"
#include "gc/space/large_object_space.h"
#include "gc/space/space.h"
#include "handle.h"
#include "obj_ptr.h"
#include "offsets.h"
#include "process_state.h"
#include "read_barrier_config.h"
#include "runtime_globals.h"
#include "scoped_thread_state_change.h"
#include "verify_object.h"
namespace art HIDDEN {
class ConditionVariable;
enum class InstructionSet;
class IsMarkedVisitor;
class Mutex;
class ReflectiveValueVisitor;
class RootVisitor;
class StackVisitor;
class Thread;
class ThreadPool;
class TimingLogger;
class VariableSizedHandleScope;
namespace mirror {
class Class;
class Object;
} // namespace mirror
namespace gc {
class AllocationListener;
class AllocRecordObjectMap;
class GcPauseListener;
class HeapTask;
class ReferenceProcessor;
class TaskProcessor;
class Verification;
namespace accounting {
template <typename T> class AtomicStack;
using ObjectStack = AtomicStack<mirror::Object>;
class CardTable;
class HeapBitmap;
class ModUnionTable;
class ReadBarrierTable;
class RememberedSet;
} // namespace accounting
namespace collector {
class ConcurrentCopying;
class GarbageCollector;
class MarkSweep;
class SemiSpace;
} // namespace collector
namespace allocator {
class RosAlloc;
} // namespace allocator
namespace space {
class AllocSpace;
class BumpPointerSpace;
class ContinuousMemMapAllocSpace;
class DiscontinuousSpace;
class DlMallocSpace;
class ImageSpace;
class LargeObjectSpace;
class MallocSpace;
class RegionSpace;
class RosAllocSpace;
class Space;
class ZygoteSpace;
} // namespace space
enum HomogeneousSpaceCompactResult {
// Success.
kSuccess,
// Reject due to disabled moving GC.
kErrorReject,
// Unsupported due to the current configuration.
kErrorUnsupported,
// System is shutting down.
kErrorVMShuttingDown,
};
// If true, use rosalloc/RosAllocSpace instead of dlmalloc/DlMallocSpace
static constexpr bool kUseRosAlloc = true;
// If true, use thread-local allocation stack.
static constexpr bool kUseThreadLocalAllocationStack = true;
class Heap {
public:
// How much we grow the TLAB if we can do it.
static constexpr size_t kPartialTlabSize = 16 * KB;
static constexpr bool kUsePartialTlabs = true;
static constexpr size_t kDefaultInitialSize = 2 * MB;
static constexpr size_t kDefaultMaximumSize = 256 * MB;
static constexpr size_t kDefaultNonMovingSpaceCapacity = 64 * MB;
static constexpr size_t kDefaultMaxFree = 32 * MB;
static constexpr size_t kDefaultMinFree = kDefaultMaxFree / 4;
static constexpr size_t kDefaultLongPauseLogThreshold = MsToNs(5);
static constexpr size_t kDefaultLongPauseLogThresholdGcStress = MsToNs(50);
static constexpr size_t kDefaultLongGCLogThreshold = MsToNs(100);
static constexpr size_t kDefaultLongGCLogThresholdGcStress = MsToNs(1000);
static constexpr size_t kDefaultTLABSize = 32 * KB;
static constexpr double kDefaultTargetUtilization = 0.6;
static constexpr double kDefaultHeapGrowthMultiplier = 2.0;
// Primitive arrays larger than this size are put in the large object space.
// TODO: Preliminary experiments suggest this value might be not optimal.
// This might benefit from further investigation.
static constexpr size_t kMinLargeObjectThreshold = 12 * KB;
static constexpr size_t kDefaultLargeObjectThreshold = kMinLargeObjectThreshold;
// Whether or not parallel GC is enabled. If not, then we never create the thread pool.
static constexpr bool kDefaultEnableParallelGC = true;
static uint8_t* const kPreferredAllocSpaceBegin;
// Whether or not we use the free list large object space. Only use it if USE_ART_LOW_4G_ALLOCATOR
// since this means that we have to use the slow msync loop in MemMap::MapAnonymous.
static constexpr space::LargeObjectSpaceType kDefaultLargeObjectSpaceType =
USE_ART_LOW_4G_ALLOCATOR ?
space::LargeObjectSpaceType::kFreeList
: space::LargeObjectSpaceType::kMap;
// Used so that we don't overflow the allocation time atomic integer.
static constexpr size_t kTimeAdjust = 1024;
// Client should call NotifyNativeAllocation every kNotifyNativeInterval allocations.
// Should be chosen so that time_to_call_mallinfo / kNotifyNativeInterval is on the same order
// as object allocation time. time_to_call_mallinfo seems to be on the order of 1 usec
// on Android.
#ifdef __ANDROID__
static constexpr uint32_t kNotifyNativeInterval = 64;
#else
// Some host mallinfo() implementations are slow. And memory is less scarce.
static constexpr uint32_t kNotifyNativeInterval = 384;
#endif
// RegisterNativeAllocation checks immediately whether GC is needed if size exceeds the
// following. kCheckImmediatelyThreshold * kNotifyNativeInterval should be small enough to
// make it safe to allocate that many bytes between checks.
static constexpr size_t kCheckImmediatelyThreshold = (10'000'000 / kNotifyNativeInterval);
// How often we allow heap trimming to happen (nanoseconds).
static constexpr uint64_t kHeapTrimWait = MsToNs(5000);
// Starting size of DlMalloc/RosAlloc spaces.
static size_t GetDefaultStartingSize() {
return gPageSize;
}
// Whether the transition-GC heap threshold condition applies or not for non-low memory devices.
// Stressing GC will bypass the heap threshold condition.
DECLARE_RUNTIME_DEBUG_FLAG(kStressCollectorTransition);
// Create a heap with the requested sizes. The possible empty
// image_file_names names specify Spaces to load based on
// ImageWriter output.
Heap(size_t initial_size,
size_t growth_limit,
size_t min_free,
size_t max_free,
double target_utilization,
double foreground_heap_growth_multiplier,
size_t stop_for_native_allocs,
size_t capacity,
size_t non_moving_space_capacity,
const std::vector<std::string>& boot_class_path,
const std::vector<std::string>& boot_class_path_locations,
ArrayRef<File> boot_class_path_files,
ArrayRef<File> boot_class_path_image_files,
ArrayRef<File> boot_class_path_vdex_files,
ArrayRef<File> boot_class_path_oat_files,
const std::vector<std::string>& image_file_names,
InstructionSet image_instruction_set,
CollectorType foreground_collector_type,
CollectorType background_collector_type,
space::LargeObjectSpaceType large_object_space_type,
size_t large_object_threshold,
size_t parallel_gc_threads,
size_t conc_gc_threads,
bool low_memory_mode,
size_t long_pause_threshold,
size_t long_gc_threshold,
bool ignore_target_footprint,
bool always_log_explicit_gcs,
bool use_tlab,
bool verify_pre_gc_heap,
bool verify_pre_sweeping_heap,
bool verify_post_gc_heap,
bool verify_pre_gc_rosalloc,
bool verify_pre_sweeping_rosalloc,
bool verify_post_gc_rosalloc,
bool gc_stress_mode,
bool measure_gc_performance,
bool use_homogeneous_space_compaction,
bool use_generational_cc,
uint64_t min_interval_homogeneous_space_compaction_by_oom,
bool dump_region_info_before_gc,
bool dump_region_info_after_gc);
~Heap();
// Allocates and initializes storage for an object instance.
template <bool kInstrumented = true, typename PreFenceVisitor>
mirror::Object* AllocObject(Thread* self,
ObjPtr<mirror::Class> klass,
size_t num_bytes,
const PreFenceVisitor& pre_fence_visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_,
!*pending_task_lock_,
!*backtrace_lock_,
!process_state_update_lock_,
!Roles::uninterruptible_) {
return AllocObjectWithAllocator<kInstrumented>(self,
klass,
num_bytes,
GetCurrentAllocator(),
pre_fence_visitor);
}
template <bool kInstrumented = true, typename PreFenceVisitor>
mirror::Object* AllocNonMovableObject(Thread* self,
ObjPtr<mirror::Class> klass,
size_t num_bytes,
const PreFenceVisitor& pre_fence_visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_,
!*pending_task_lock_,
!*backtrace_lock_,
!process_state_update_lock_,
!Roles::uninterruptible_) {
mirror::Object* obj = AllocObjectWithAllocator<kInstrumented>(self,
klass,
num_bytes,
GetCurrentNonMovingAllocator(),
pre_fence_visitor);
// Java Heap Profiler check and sample allocation.
if (GetHeapSampler().IsEnabled()) {
JHPCheckNonTlabSampleAllocation(self, obj, num_bytes);
}
return obj;
}
template <bool kInstrumented = true, bool kCheckLargeObject = true, typename PreFenceVisitor>
ALWAYS_INLINE mirror::Object* AllocObjectWithAllocator(Thread* self,
ObjPtr<mirror::Class> klass,
size_t byte_count,
AllocatorType allocator,
const PreFenceVisitor& pre_fence_visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_,
!*pending_task_lock_,
!*backtrace_lock_,
!process_state_update_lock_,
!Roles::uninterruptible_);
AllocatorType GetCurrentAllocator() const {
return current_allocator_;
}
AllocatorType GetCurrentNonMovingAllocator() const {
return current_non_moving_allocator_;
}
AllocatorType GetUpdatedAllocator(AllocatorType old_allocator) {
return (old_allocator == kAllocatorTypeNonMoving) ?
GetCurrentNonMovingAllocator() : GetCurrentAllocator();
}
// Visit all of the live objects in the heap.
template <typename Visitor>
ALWAYS_INLINE void VisitObjects(Visitor&& visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::heap_bitmap_lock_, !*gc_complete_lock_);
template <typename Visitor>
ALWAYS_INLINE void VisitObjectsPaused(Visitor&& visitor)
REQUIRES(Locks::mutator_lock_, !Locks::heap_bitmap_lock_, !*gc_complete_lock_);
void VisitReflectiveTargets(ReflectiveValueVisitor* visitor)
REQUIRES(Locks::mutator_lock_, !Locks::heap_bitmap_lock_, !*gc_complete_lock_);
void CheckPreconditionsForAllocObject(ObjPtr<mirror::Class> c, size_t byte_count)
REQUIRES_SHARED(Locks::mutator_lock_);
// Inform the garbage collector of a non-malloc allocated native memory that might become
// reclaimable in the future as a result of Java garbage collection.
void RegisterNativeAllocation(JNIEnv* env, size_t bytes)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
void RegisterNativeFree(JNIEnv* env, size_t bytes);
// Notify the garbage collector of malloc allocations that might be reclaimable
// as a result of Java garbage collection. Each such call represents approximately
// kNotifyNativeInterval such allocations.
void NotifyNativeAllocations(JNIEnv* env)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
uint32_t GetNotifyNativeInterval() {
return kNotifyNativeInterval;
}
// Change the allocator, updates entrypoints.
void ChangeAllocator(AllocatorType allocator)
REQUIRES(Locks::mutator_lock_, !Locks::runtime_shutdown_lock_);
// Change the collector to be one of the possible options (MS, CMS, SS). Only safe when no
// concurrent accesses to the heap are possible.
void ChangeCollector(CollectorType collector_type)
REQUIRES(Locks::mutator_lock_, !*gc_complete_lock_);
// The given reference is believed to be to an object in the Java heap, check the soundness of it.
// TODO: NO_THREAD_SAFETY_ANALYSIS since we call this everywhere and it is impossible to find a
// proper lock ordering for it.
void VerifyObjectBody(ObjPtr<mirror::Object> o) NO_THREAD_SAFETY_ANALYSIS;
// Consistency check of all live references.
void VerifyHeap() REQUIRES(!Locks::heap_bitmap_lock_);
// Returns how many failures occured.
size_t VerifyHeapReferences(bool verify_referents = true)
REQUIRES(Locks::mutator_lock_, !*gc_complete_lock_);
bool VerifyMissingCardMarks()
REQUIRES(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
// 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 IsValidObjectAddress(const void* obj) const REQUIRES_SHARED(Locks::mutator_lock_);
// Faster alternative to IsHeapAddress since finding if an object is in the large object space is
// very slow.
bool IsNonDiscontinuousSpaceHeapAddress(const void* addr) const
REQUIRES_SHARED(Locks::mutator_lock_);
// Returns true if 'obj' is a live heap object, false otherwise (including for invalid addresses).
// Requires the heap lock to be held.
bool IsLiveObjectLocked(ObjPtr<mirror::Object> obj,
bool search_allocation_stack = true,
bool search_live_stack = true,
bool sorted = false)
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
// Returns true if there is any chance that the object (obj) will move.
bool IsMovableObject(ObjPtr<mirror::Object> obj) const REQUIRES_SHARED(Locks::mutator_lock_);
// Enables us to compacting GC until objects are released.
EXPORT void IncrementDisableMovingGC(Thread* self) REQUIRES(!*gc_complete_lock_);
EXPORT void DecrementDisableMovingGC(Thread* self) REQUIRES(!*gc_complete_lock_);
// Temporarily disable thread flip for JNI critical calls.
void IncrementDisableThreadFlip(Thread* self) REQUIRES(!*thread_flip_lock_);
void DecrementDisableThreadFlip(Thread* self) REQUIRES(!*thread_flip_lock_);
void ThreadFlipBegin(Thread* self) REQUIRES(!*thread_flip_lock_);
void ThreadFlipEnd(Thread* self) REQUIRES(!*thread_flip_lock_);
// Ensures that the obj doesn't cause userfaultfd in JNI critical calls.
void EnsureObjectUserfaulted(ObjPtr<mirror::Object> obj) REQUIRES_SHARED(Locks::mutator_lock_);
// Clear all of the mark bits, doesn't clear bitmaps which have the same live bits as mark bits.
// Mutator lock is required for GetContinuousSpaces.
void ClearMarkedObjects(bool release_eagerly = true)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Initiates an explicit garbage collection. Guarantees that a GC started after this call has
// completed.
EXPORT void CollectGarbage(bool clear_soft_references, GcCause cause = kGcCauseExplicit)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
// Does a concurrent GC, provided the GC numbered requested_gc_num has not already been
// completed. Should only be called by the GC daemon thread through runtime.
void ConcurrentGC(Thread* self, GcCause cause, bool force_full, uint32_t requested_gc_num)
REQUIRES(!Locks::runtime_shutdown_lock_, !*gc_complete_lock_,
!*pending_task_lock_, !process_state_update_lock_);
// Implements VMDebug.countInstancesOfClass and JDWP VM_InstanceCount.
// The boolean decides whether to use IsAssignableFrom or == when comparing classes.
void CountInstances(const std::vector<Handle<mirror::Class>>& classes,
bool use_is_assignable_from,
uint64_t* counts)
REQUIRES(!Locks::heap_bitmap_lock_, !*gc_complete_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// 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() REQUIRES(!*gc_complete_lock_);
// Make the current growth limit the new maximum capacity, unmaps pages at the end of spaces
// which will never be used. Used to implement dalvik.system.VMRuntime.clampGrowthLimit.
void ClampGrowthLimit() REQUIRES(!Locks::heap_bitmap_lock_);
// Target ideal heap utilization ratio, implements
// dalvik.system.VMRuntime.getTargetHeapUtilization.
double GetTargetHeapUtilization() const {
return target_utilization_;
}
// Data structure memory usage tracking.
void RegisterGCAllocation(size_t bytes);
void RegisterGCDeAllocation(size_t bytes);
// Set the heap's private space pointers to be the same as the space based on it's type. Public
// due to usage by tests.
void SetSpaceAsDefault(space::ContinuousSpace* continuous_space)
REQUIRES(!Locks::heap_bitmap_lock_);
void AddSpace(space::Space* space)
REQUIRES(!Locks::heap_bitmap_lock_)
REQUIRES(Locks::mutator_lock_);
void RemoveSpace(space::Space* space)
REQUIRES(!Locks::heap_bitmap_lock_)
REQUIRES(Locks::mutator_lock_);
double GetPreGcWeightedAllocatedBytes() const {
return pre_gc_weighted_allocated_bytes_;
}
double GetPostGcWeightedAllocatedBytes() const {
return post_gc_weighted_allocated_bytes_;
}
void CalculatePreGcWeightedAllocatedBytes();
void CalculatePostGcWeightedAllocatedBytes();
uint64_t GetTotalGcCpuTime();
uint64_t GetProcessCpuStartTime() const {
return process_cpu_start_time_ns_;
}
uint64_t GetPostGCLastProcessCpuTime() const {
return post_gc_last_process_cpu_time_ns_;
}
// Set target ideal heap utilization ratio, implements
// dalvik.system.VMRuntime.setTargetHeapUtilization.
void SetTargetHeapUtilization(float 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.
// Set while we hold gc_complete_lock or collector_type_running_ != kCollectorTypeNone.
void SetIdealFootprint(size_t max_allowed_footprint);
// Blocks the caller until the garbage collector becomes idle and returns the type of GC we
// waited for. Only waits for running collections, ignoring a requested but unstarted GC. Only
// heuristic, since a new GC may have started by the time we return.
EXPORT collector::GcType WaitForGcToComplete(GcCause cause, Thread* self)
REQUIRES(!*gc_complete_lock_);
// Update the heap's process state to a new value, may cause compaction to occur.
void UpdateProcessState(ProcessState old_process_state, ProcessState new_process_state)
REQUIRES(!*pending_task_lock_, !*gc_complete_lock_, !process_state_update_lock_);
bool HaveContinuousSpaces() const NO_THREAD_SAFETY_ANALYSIS {
// No lock since vector empty is thread safe.
return !continuous_spaces_.empty();
}
const std::vector<space::ContinuousSpace*>& GetContinuousSpaces() const
REQUIRES_SHARED(Locks::mutator_lock_) {
return continuous_spaces_;
}
const std::vector<space::DiscontinuousSpace*>& GetDiscontinuousSpaces() const {
return discontinuous_spaces_;
}
const collector::Iteration* GetCurrentGcIteration() const {
return &current_gc_iteration_;
}
collector::Iteration* GetCurrentGcIteration() {
return &current_gc_iteration_;
}
// Enable verification of object references when the runtime is sufficiently initialized.
void EnableObjectValidation() {
verify_object_mode_ = kVerifyObjectSupport;
if (verify_object_mode_ > kVerifyObjectModeDisabled) {
VerifyHeap();
}
}
// Disable object reference verification for image writing.
void DisableObjectValidation() {
verify_object_mode_ = kVerifyObjectModeDisabled;
}
// Other checks may be performed if we know the heap should be in a healthy state.
bool IsObjectValidationEnabled() const {
return verify_object_mode_ > kVerifyObjectModeDisabled;
}
// Returns true if low memory mode is enabled.
bool IsLowMemoryMode() const {
return low_memory_mode_;
}
// Returns the heap growth multiplier, this affects how much we grow the heap after a GC.
// Scales heap growth, min free, and max free.
double HeapGrowthMultiplier() const;
// Freed bytes can be negative in cases where we copy objects from a compacted space to a
// free-list backed space.
void RecordFree(uint64_t freed_objects, int64_t freed_bytes);
// Record the bytes freed by thread-local buffer revoke.
void RecordFreeRevoke();
accounting::CardTable* GetCardTable() const {
return card_table_.get();
}
accounting::ReadBarrierTable* GetReadBarrierTable() const {
return rb_table_.get();
}
EXPORT void AddFinalizerReference(Thread* self, ObjPtr<mirror::Object>* object);
// Returns the number of bytes currently allocated.
// The result should be treated as an approximation, if it is being concurrently updated.
size_t GetBytesAllocated() const {
return num_bytes_allocated_.load(std::memory_order_relaxed);
}
// Returns bytes_allocated before adding 'bytes' to it.
size_t AddBytesAllocated(size_t bytes) {
return num_bytes_allocated_.fetch_add(bytes, std::memory_order_relaxed);
}
bool GetUseGenerationalCC() const {
return use_generational_cc_;
}
// Returns the number of objects currently allocated.
size_t GetObjectsAllocated() const
REQUIRES(!Locks::heap_bitmap_lock_);
// Returns the total number of bytes allocated since the heap was created.
uint64_t GetBytesAllocatedEver() const;
// Returns the total number of bytes freed since the heap was created.
// Can decrease over time, and may even be negative, since moving an object to
// a space in which it occupies more memory results in negative "freed bytes".
// With default memory order, this should be viewed only as a hint.
int64_t GetBytesFreedEver(std::memory_order mo = std::memory_order_relaxed) const {
return total_bytes_freed_ever_.load(mo);
}
space::RegionSpace* GetRegionSpace() const {
return region_space_;
}
space::BumpPointerSpace* GetBumpPointerSpace() const {
return bump_pointer_space_;
}
// Implements java.lang.Runtime.maxMemory, returning the maximum amount of memory a program can
// consume. For a regular VM this would relate to the -Xmx option and would return -1 if no Xmx
// were specified. Android apps start with a growth limit (small heap size) which is
// cleared/extended for large apps.
size_t GetMaxMemory() const {
// There are some race conditions in the allocation code that can cause bytes allocated to
// become larger than growth_limit_ in rare cases.
return std::max(GetBytesAllocated(), growth_limit_);
}
// Implements java.lang.Runtime.totalMemory, returning approximate amount of memory currently
// consumed by an application.
EXPORT size_t GetTotalMemory() const;
// Returns approximately how much free memory we have until the next GC happens.
size_t GetFreeMemoryUntilGC() const {
return UnsignedDifference(target_footprint_.load(std::memory_order_relaxed),
GetBytesAllocated());
}
// Returns approximately how much free memory we have until the next OOME happens.
size_t GetFreeMemoryUntilOOME() const {
return UnsignedDifference(growth_limit_, GetBytesAllocated());
}
// Returns how much free memory we have until we need to grow the heap to perform an allocation.
// Similar to GetFreeMemoryUntilGC. Implements java.lang.Runtime.freeMemory.
size_t GetFreeMemory() const {
return UnsignedDifference(GetTotalMemory(),
num_bytes_allocated_.load(std::memory_order_relaxed));
}
// Get the space that corresponds to an object's address. Current implementation searches all
// spaces in turn. If fail_ok is false then failing to find a space will cause an abort.
// TODO: consider using faster data structure like binary tree.
EXPORT space::ContinuousSpace* FindContinuousSpaceFromObject(ObjPtr<mirror::Object>,
bool fail_ok) const
REQUIRES_SHARED(Locks::mutator_lock_);
space::ContinuousSpace* FindContinuousSpaceFromAddress(const mirror::Object* addr) const
REQUIRES_SHARED(Locks::mutator_lock_);
space::DiscontinuousSpace* FindDiscontinuousSpaceFromObject(ObjPtr<mirror::Object>,
bool fail_ok) const
REQUIRES_SHARED(Locks::mutator_lock_);
EXPORT space::Space* FindSpaceFromObject(ObjPtr<mirror::Object> obj, bool fail_ok) const
REQUIRES_SHARED(Locks::mutator_lock_);
space::Space* FindSpaceFromAddress(const void* ptr) const
REQUIRES_SHARED(Locks::mutator_lock_);
std::string DumpSpaceNameFromAddress(const void* addr) const
REQUIRES_SHARED(Locks::mutator_lock_);
void DumpForSigQuit(std::ostream& os) REQUIRES(!*gc_complete_lock_);
// Do a pending collector transition.
void DoPendingCollectorTransition()
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
// Deflate monitors, ... and trim the spaces.
EXPORT void Trim(Thread* self) REQUIRES(!*gc_complete_lock_);
void RevokeThreadLocalBuffers(Thread* thread);
void RevokeRosAllocThreadLocalBuffers(Thread* thread);
void RevokeAllThreadLocalBuffers();
void AssertThreadLocalBuffersAreRevoked(Thread* thread);
void AssertAllBumpPointerSpaceThreadLocalBuffersAreRevoked();
void RosAllocVerification(TimingLogger* timings, const char* name)
REQUIRES(Locks::mutator_lock_);
accounting::HeapBitmap* GetLiveBitmap() REQUIRES_SHARED(Locks::heap_bitmap_lock_) {
return live_bitmap_.get();
}
accounting::HeapBitmap* GetMarkBitmap() REQUIRES_SHARED(Locks::heap_bitmap_lock_) {
return mark_bitmap_.get();
}
accounting::ObjectStack* GetLiveStack() REQUIRES_SHARED(Locks::heap_bitmap_lock_) {
return live_stack_.get();
}
accounting::ObjectStack* GetAllocationStack() REQUIRES_SHARED(Locks::heap_bitmap_lock_) {
return allocation_stack_.get();
}
void PreZygoteFork() NO_THREAD_SAFETY_ANALYSIS;
// Mark and empty stack.
EXPORT void FlushAllocStack() REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::heap_bitmap_lock_);
// Revoke all the thread-local allocation stacks.
EXPORT void RevokeAllThreadLocalAllocationStacks(Thread* self)
REQUIRES(Locks::mutator_lock_, !Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_);
// Mark all the objects in the allocation stack in the specified bitmap.
// TODO: Refactor?
void MarkAllocStack(accounting::ContinuousSpaceBitmap* bitmap1,
accounting::ContinuousSpaceBitmap* bitmap2,
accounting::LargeObjectBitmap* large_objects,
accounting::ObjectStack* stack)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::heap_bitmap_lock_);
// Mark the specified allocation stack as live.
void MarkAllocStackAsLive(accounting::ObjectStack* stack)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::heap_bitmap_lock_);
// Unbind any bound bitmaps.
void UnBindBitmaps()
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Returns the boot image spaces. There may be multiple boot image spaces.
const std::vector<space::ImageSpace*>& GetBootImageSpaces() const {
return boot_image_spaces_;
}
// TODO(b/260881207): refactor to only use this function in debug builds and
// remove EXPORT.
EXPORT bool ObjectIsInBootImageSpace(ObjPtr<mirror::Object> obj) const
REQUIRES_SHARED(Locks::mutator_lock_);
bool IsInBootImageOatFile(const void* p) const
REQUIRES_SHARED(Locks::mutator_lock_);
// Get the start address of the boot images if any; otherwise returns 0.
uint32_t GetBootImagesStartAddress() const {
return boot_images_start_address_;
}
// Get the size of all boot images, including the heap and oat areas.
uint32_t GetBootImagesSize() const {
return boot_images_size_;
}
// Check if a pointer points to a boot image.
bool IsBootImageAddress(const void* p) const {
return reinterpret_cast<uintptr_t>(p) - boot_images_start_address_ < boot_images_size_;
}
space::DlMallocSpace* GetDlMallocSpace() const {
return dlmalloc_space_;
}
space::RosAllocSpace* GetRosAllocSpace() const {
return rosalloc_space_;
}
// Return the corresponding rosalloc space.
space::RosAllocSpace* GetRosAllocSpace(gc::allocator::RosAlloc* rosalloc) const
REQUIRES_SHARED(Locks::mutator_lock_);
space::MallocSpace* GetNonMovingSpace() const {
return non_moving_space_;
}
space::LargeObjectSpace* GetLargeObjectsSpace() const {
return large_object_space_;
}
// Returns the free list space that may contain movable objects (the
// one that's not the non-moving space), either rosalloc_space_ or
// dlmalloc_space_.
space::MallocSpace* GetPrimaryFreeListSpace() {
if (kUseRosAlloc) {
DCHECK(rosalloc_space_ != nullptr);
// reinterpret_cast is necessary as the space class hierarchy
// isn't known (#included) yet here.
return reinterpret_cast<space::MallocSpace*>(rosalloc_space_);
} else {
DCHECK(dlmalloc_space_ != nullptr);
return reinterpret_cast<space::MallocSpace*>(dlmalloc_space_);
}
}
void DumpSpaces(std::ostream& stream) const REQUIRES_SHARED(Locks::mutator_lock_);
EXPORT std::string DumpSpaces() const REQUIRES_SHARED(Locks::mutator_lock_);
// GC performance measuring
void DumpGcPerformanceInfo(std::ostream& os)
REQUIRES(!*gc_complete_lock_);
void ResetGcPerformanceInfo() REQUIRES(!*gc_complete_lock_);
// Thread pool. Create either the given number of threads, or as per the
// values of conc_gc_threads_ and parallel_gc_threads_.
void CreateThreadPool(size_t num_threads = 0);
void WaitForWorkersToBeCreated();
void DeleteThreadPool();
ThreadPool* GetThreadPool() {
return thread_pool_.get();
}
size_t GetParallelGCThreadCount() const {
return parallel_gc_threads_;
}
size_t GetConcGCThreadCount() const {
return conc_gc_threads_;
}
accounting::ModUnionTable* FindModUnionTableFromSpace(space::Space* space);
void AddModUnionTable(accounting::ModUnionTable* mod_union_table);
accounting::RememberedSet* FindRememberedSetFromSpace(space::Space* space);
void AddRememberedSet(accounting::RememberedSet* remembered_set);
// Also deletes the remebered set.
void RemoveRememberedSet(space::Space* space);
bool IsCompilingBoot() const;
bool HasBootImageSpace() const {
return !boot_image_spaces_.empty();
}
bool HasAppImageSpace() const {
ScopedObjectAccess soa(Thread::Current());
for (const space::ContinuousSpace* space : continuous_spaces_) {
// An image space is either a boot image space or an app image space.
if (space->IsImageSpace() && !IsBootImageAddress(space->Begin())) {
return true;
}
}
return false;
}
ReferenceProcessor* GetReferenceProcessor() {
return reference_processor_.get();
}
TaskProcessor* GetTaskProcessor() {
return task_processor_.get();
}
bool HasZygoteSpace() const {
return zygote_space_ != nullptr;
}
// Returns the active concurrent copying collector.
collector::ConcurrentCopying* ConcurrentCopyingCollector() {
collector::ConcurrentCopying* active_collector =
active_concurrent_copying_collector_.load(std::memory_order_relaxed);
if (use_generational_cc_) {
DCHECK((active_collector == concurrent_copying_collector_) ||
(active_collector == young_concurrent_copying_collector_))
<< "active_concurrent_copying_collector: " << active_collector
<< " young_concurrent_copying_collector: " << young_concurrent_copying_collector_
<< " concurrent_copying_collector: " << concurrent_copying_collector_;
} else {
DCHECK_EQ(active_collector, concurrent_copying_collector_);
}
return active_collector;
}
collector::MarkCompact* MarkCompactCollector() {
DCHECK(!gUseUserfaultfd || mark_compact_ != nullptr);
return mark_compact_;
}
bool IsPerformingUffdCompaction() { return gUseUserfaultfd && mark_compact_->IsCompacting(); }
CollectorType CurrentCollectorType() const {
DCHECK(!gUseUserfaultfd || collector_type_ == kCollectorTypeCMC);
return collector_type_;
}
bool IsMovingGc() const { return IsMovingGc(CurrentCollectorType()); }
CollectorType GetForegroundCollectorType() const { return foreground_collector_type_; }
// EXPORT is needed to make this method visible for libartservice.
EXPORT std::string GetForegroundCollectorName();
bool IsGcConcurrentAndMoving() const {
if (IsGcConcurrent() && IsMovingGc(collector_type_)) {
// Assume no transition when a concurrent moving collector is used.
DCHECK_EQ(collector_type_, foreground_collector_type_);
return true;
}
return false;
}
bool IsMovingGCDisabled(Thread* self) REQUIRES(!*gc_complete_lock_) {
MutexLock mu(self, *gc_complete_lock_);
return disable_moving_gc_count_ > 0;
}
// Request an asynchronous trim.
void RequestTrim(Thread* self) REQUIRES(!*pending_task_lock_);
// Retrieve the current GC number, i.e. the number n such that we completed n GCs so far.
// Provides acquire ordering, so that if we read this first, and then check whether a GC is
// required, we know that the GC number read actually preceded the test.
uint32_t GetCurrentGcNum() {
return gcs_completed_.load(std::memory_order_acquire);
}
// Request asynchronous GC. Observed_gc_num is the value of GetCurrentGcNum() when we started to
// evaluate the GC triggering condition. If a GC has been completed since then, we consider our
// job done. If we return true, then we ensured that gcs_completed_ will eventually be
// incremented beyond observed_gc_num. We return false only in corner cases in which we cannot
// ensure that.
bool RequestConcurrentGC(Thread* self, GcCause cause, bool force_full, uint32_t observed_gc_num)
REQUIRES(!*pending_task_lock_);
// Whether or not we may use a garbage collector, used so that we only create collectors we need.
bool MayUseCollector(CollectorType type) const;
// Used by tests to reduce timinig-dependent flakiness in OOME behavior.
void SetMinIntervalHomogeneousSpaceCompactionByOom(uint64_t interval) {
min_interval_homogeneous_space_compaction_by_oom_ = interval;
}
// Helpers for android.os.Debug.getRuntimeStat().
uint64_t GetGcCount() const;
uint64_t GetGcTime() const;
uint64_t GetBlockingGcCount() const;
uint64_t GetBlockingGcTime() const;
void DumpGcCountRateHistogram(std::ostream& os) const REQUIRES(!*gc_complete_lock_);
void DumpBlockingGcCountRateHistogram(std::ostream& os) const REQUIRES(!*gc_complete_lock_);
uint64_t GetTotalTimeWaitingForGC() const {
return total_wait_time_;
}
uint64_t GetPreOomeGcCount() const;
// Perfetto Art Heap Profiler Support.
HeapSampler& GetHeapSampler() {
return heap_sampler_;
}
void InitPerfettoJavaHeapProf();
// In NonTlab case: Check whether we should report a sample allocation and if so report it.
// Also update state (bytes_until_sample).
// By calling JHPCheckNonTlabSampleAllocation from different functions for Large allocations and
// non-moving allocations we are able to use the stack to identify these allocations separately.
EXPORT void JHPCheckNonTlabSampleAllocation(Thread* self, mirror::Object* ret, size_t alloc_size);
// In Tlab case: Calculate the next tlab size (location of next sample point) and whether
// a sample should be taken.
size_t JHPCalculateNextTlabSize(Thread* self,
size_t jhp_def_tlab_size,
size_t alloc_size,
bool* take_sample,
size_t* bytes_until_sample);
// Reduce the number of bytes to the next sample position by this adjustment.
void AdjustSampleOffset(size_t adjustment);
// Allocation tracking support
// Callers to this function use double-checked locking to ensure safety on allocation_records_
bool IsAllocTrackingEnabled() const {
return alloc_tracking_enabled_.load(std::memory_order_relaxed);
}
void SetAllocTrackingEnabled(bool enabled) REQUIRES(Locks::alloc_tracker_lock_) {
alloc_tracking_enabled_.store(enabled, std::memory_order_relaxed);
}
// Return the current stack depth of allocation records.
size_t GetAllocTrackerStackDepth() const {
return alloc_record_depth_;
}
// Return the current stack depth of allocation records.
void SetAllocTrackerStackDepth(size_t alloc_record_depth) {
alloc_record_depth_ = alloc_record_depth;
}
AllocRecordObjectMap* GetAllocationRecords() const REQUIRES(Locks::alloc_tracker_lock_) {
return allocation_records_.get();
}
void SetAllocationRecords(AllocRecordObjectMap* records)
REQUIRES(Locks::alloc_tracker_lock_);
void VisitAllocationRecords(RootVisitor* visitor) const
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::alloc_tracker_lock_);
void SweepAllocationRecords(IsMarkedVisitor* visitor) const
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::alloc_tracker_lock_);
void DisallowNewAllocationRecords() const
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::alloc_tracker_lock_);
void AllowNewAllocationRecords() const
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::alloc_tracker_lock_);
void BroadcastForNewAllocationRecords() const
REQUIRES(!Locks::alloc_tracker_lock_);
void DisableGCForShutdown() REQUIRES(!*gc_complete_lock_);
bool IsGCDisabledForShutdown() const REQUIRES(!*gc_complete_lock_);
// Create a new alloc space and compact default alloc space to it.
EXPORT HomogeneousSpaceCompactResult PerformHomogeneousSpaceCompact()
REQUIRES(!*gc_complete_lock_, !process_state_update_lock_);
EXPORT bool SupportHomogeneousSpaceCompactAndCollectorTransitions() const;
// Install an allocation listener.
EXPORT void SetAllocationListener(AllocationListener* l);
// Remove an allocation listener. Note: the listener must not be deleted, as for performance
// reasons, we assume it stays valid when we read it (so that we don't require a lock).
EXPORT void RemoveAllocationListener();
// Install a gc pause listener.
EXPORT void SetGcPauseListener(GcPauseListener* l);
// Get the currently installed gc pause listener, or null.
GcPauseListener* GetGcPauseListener() {
return gc_pause_listener_.load(std::memory_order_acquire);
}
// Remove a gc pause listener. Note: the listener must not be deleted, as for performance
// reasons, we assume it stays valid when we read it (so that we don't require a lock).
EXPORT void RemoveGcPauseListener();
EXPORT const Verification* GetVerification() const;
void PostForkChildAction(Thread* self) REQUIRES(!*gc_complete_lock_);
EXPORT void TraceHeapSize(size_t heap_size);
bool AddHeapTask(gc::HeapTask* task);
// TODO: Kernels for arm and x86 in both, 32-bit and 64-bit modes use 512 entries per page-table
// page. Find a way to confirm that in userspace.
// Address range covered by 1 Page Middle Directory (PMD) entry in the page table
static inline ALWAYS_INLINE size_t GetPMDSize() {
return (gPageSize / sizeof(uint64_t)) * gPageSize;
}
// Address range covered by 1 Page Upper Directory (PUD) entry in the page table
static inline ALWAYS_INLINE size_t GetPUDSize() {
return (gPageSize / sizeof(uint64_t)) * GetPMDSize();
}
// Returns the ideal alignment corresponding to page-table levels for the
// given size.
static inline size_t BestPageTableAlignment(size_t size) {
const size_t pud_size = GetPUDSize();
const size_t pmd_size = GetPMDSize();
return size < pud_size ? pmd_size : pud_size;
}
private:
class ConcurrentGCTask;
class CollectorTransitionTask;
class HeapTrimTask;
class TriggerPostForkCCGcTask;
class ReduceTargetFootprintTask;
// Compact source space to target space. Returns the collector used.
collector::GarbageCollector* Compact(space::ContinuousMemMapAllocSpace* target_space,
space::ContinuousMemMapAllocSpace* source_space,
GcCause gc_cause)
REQUIRES(Locks::mutator_lock_);
void LogGC(GcCause gc_cause, collector::GarbageCollector* collector);
void StartGC(Thread* self, GcCause cause, CollectorType collector_type)
REQUIRES(!*gc_complete_lock_);
void FinishGC(Thread* self, collector::GcType gc_type) REQUIRES(!*gc_complete_lock_);
double CalculateGcWeightedAllocatedBytes(uint64_t gc_last_process_cpu_time_ns,
uint64_t current_process_cpu_time) const;
// Create a mem map with a preferred base address.
static MemMap MapAnonymousPreferredAddress(const char* name,
uint8_t* request_begin,
size_t capacity,
std::string* out_error_str);
bool SupportHSpaceCompaction() const {
// Returns true if we can do hspace compaction
return main_space_backup_ != nullptr;
}
// Size_t saturating arithmetic
static ALWAYS_INLINE size_t UnsignedDifference(size_t x, size_t y) {
return x > y ? x - y : 0;
}
static ALWAYS_INLINE size_t UnsignedSum(size_t x, size_t y) {
return x + y >= x ? x + y : std::numeric_limits<size_t>::max();
}
static ALWAYS_INLINE bool AllocatorHasAllocationStack(AllocatorType allocator_type) {
return
allocator_type != kAllocatorTypeRegionTLAB &&
allocator_type != kAllocatorTypeBumpPointer &&
allocator_type != kAllocatorTypeTLAB &&
allocator_type != kAllocatorTypeRegion;
}
static bool IsMovingGc(CollectorType collector_type) {
return
collector_type == kCollectorTypeCC ||
collector_type == kCollectorTypeSS ||
collector_type == kCollectorTypeCMC ||
collector_type == kCollectorTypeCCBackground ||
collector_type == kCollectorTypeCMCBackground ||
collector_type == kCollectorTypeHomogeneousSpaceCompact;
}
bool ShouldAllocLargeObject(ObjPtr<mirror::Class> c, size_t byte_count) const
REQUIRES_SHARED(Locks::mutator_lock_);
// Checks whether we should garbage collect:
ALWAYS_INLINE bool ShouldConcurrentGCForJava(size_t new_num_bytes_allocated);
float NativeMemoryOverTarget(size_t current_native_bytes, bool is_gc_concurrent);
void CheckGCForNative(Thread* self)
REQUIRES(!*pending_task_lock_, !*gc_complete_lock_, !process_state_update_lock_);
accounting::ObjectStack* GetMarkStack() {
return mark_stack_.get();
}
// We don't force this to be inlined since it is a slow path.
template <bool kInstrumented, typename PreFenceVisitor>
mirror::Object* AllocLargeObject(Thread* self,
ObjPtr<mirror::Class>* klass,
size_t byte_count,
const PreFenceVisitor& pre_fence_visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_,
!*backtrace_lock_, !process_state_update_lock_);
// Handles Allocate()'s slow allocation path with GC involved after an initial allocation
// attempt failed.
// Called with thread suspension disallowed, but re-enables it, and may suspend, internally.
// Returns null if instrumentation or the allocator changed.
EXPORT mirror::Object* AllocateInternalWithGc(Thread* self,
AllocatorType allocator,
bool instrumented,
size_t num_bytes,
size_t* bytes_allocated,
size_t* usable_size,
size_t* bytes_tl_bulk_allocated,
ObjPtr<mirror::Class>* klass)
REQUIRES(!Locks::thread_suspend_count_lock_, !*gc_complete_lock_, !*pending_task_lock_)
REQUIRES(Roles::uninterruptible_) REQUIRES_SHARED(Locks::mutator_lock_);
// Allocate into a specific space.
mirror::Object* AllocateInto(Thread* self,
space::AllocSpace* space,
ObjPtr<mirror::Class> c,
size_t bytes)
REQUIRES_SHARED(Locks::mutator_lock_);
// Need to do this with mutators paused so that somebody doesn't accidentally allocate into the
// wrong space.
void SwapSemiSpaces() REQUIRES(Locks::mutator_lock_);
// Try to allocate a number of bytes, this function never does any GCs. Needs to be inlined so
// that the switch statement is constant optimized in the entrypoints.
template <const bool kInstrumented, const bool kGrow>
ALWAYS_INLINE mirror::Object* TryToAllocate(Thread* self,
AllocatorType allocator_type,
size_t alloc_size,
size_t* bytes_allocated,
size_t* usable_size,
size_t* bytes_tl_bulk_allocated)
REQUIRES_SHARED(Locks::mutator_lock_);
EXPORT mirror::Object* AllocWithNewTLAB(Thread* self,
AllocatorType allocator_type,
size_t alloc_size,
bool grow,
size_t* bytes_allocated,
size_t* usable_size,
size_t* bytes_tl_bulk_allocated)
REQUIRES_SHARED(Locks::mutator_lock_);
void ThrowOutOfMemoryError(Thread* self, size_t byte_count, AllocatorType allocator_type)
REQUIRES_SHARED(Locks::mutator_lock_);
// Are we out of memory, and thus should force a GC or fail?
// For concurrent collectors, out of memory is defined by growth_limit_.
// For nonconcurrent collectors it is defined by target_footprint_ unless grow is
// set. If grow is set, the limit is growth_limit_ and we adjust target_footprint_
// to accomodate the allocation.
ALWAYS_INLINE bool IsOutOfMemoryOnAllocation(AllocatorType allocator_type,
size_t alloc_size,
bool grow);
// Blocks the caller until the garbage collector becomes idle and returns the type of GC we
// waited for.
collector::GcType WaitForGcToCompleteLocked(GcCause cause, Thread* self)
REQUIRES(gc_complete_lock_);
void RequestCollectorTransition(CollectorType desired_collector_type, uint64_t delta_time)
REQUIRES(!*pending_task_lock_);
EXPORT void RequestConcurrentGCAndSaveObject(Thread* self,
bool force_full,
uint32_t observed_gc_num,
ObjPtr<mirror::Object>* obj)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!*pending_task_lock_);
static constexpr uint32_t GC_NUM_ANY = std::numeric_limits<uint32_t>::max();
// Sometimes CollectGarbageInternal decides to run a different Gc than you requested. Returns
// which type of Gc was actually run.
// We pass in the intended GC sequence number to ensure that multiple approximately concurrent
// requests result in a single GC; clearly redundant request will be pruned. A requested_gc_num
// of GC_NUM_ANY indicates that we should not prune redundant requests. (In the unlikely case
// that gcs_completed_ gets this big, we just accept a potential extra GC or two.)
collector::GcType CollectGarbageInternal(collector::GcType gc_plan,
GcCause gc_cause,
bool clear_soft_references,
uint32_t requested_gc_num)
REQUIRES(!*gc_complete_lock_, !Locks::heap_bitmap_lock_, !Locks::thread_suspend_count_lock_,
!*pending_task_lock_, !process_state_update_lock_);
void PreGcVerification(collector::GarbageCollector* gc)
REQUIRES(!Locks::mutator_lock_, !*gc_complete_lock_);
void PreGcVerificationPaused(collector::GarbageCollector* gc)
REQUIRES(Locks::mutator_lock_, !*gc_complete_lock_);
void PrePauseRosAllocVerification(collector::GarbageCollector* gc)
REQUIRES(Locks::mutator_lock_);
void PreSweepingGcVerification(collector::GarbageCollector* gc)
REQUIRES(Locks::mutator_lock_, !Locks::heap_bitmap_lock_, !*gc_complete_lock_);
void PostGcVerification(collector::GarbageCollector* gc)
REQUIRES(!Locks::mutator_lock_, !*gc_complete_lock_);
void PostGcVerificationPaused(collector::GarbageCollector* gc)
REQUIRES(Locks::mutator_lock_, !*gc_complete_lock_);
// Find a collector based on GC type.
collector::GarbageCollector* FindCollectorByGcType(collector::GcType gc_type);
// Create the main free list malloc space, either a RosAlloc space or DlMalloc space.
void CreateMainMallocSpace(MemMap&& mem_map,
size_t initial_size,
size_t growth_limit,
size_t capacity);
// Create a malloc space based on a mem map. Does not set the space as default.
space::MallocSpace* CreateMallocSpaceFromMemMap(MemMap&& mem_map,
size_t initial_size,
size_t growth_limit,
size_t capacity,
const char* name,
bool can_move_objects);
// 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. bytes_allocated_before_gc is used to measure bytes / second for the period which
// the GC was run.
// This is only called by the thread that set collector_type_running_ to a value other than
// kCollectorTypeNone, or while holding gc_complete_lock, and ensuring that
// collector_type_running_ is kCollectorTypeNone.
void GrowForUtilization(collector::GarbageCollector* collector_ran,
size_t bytes_allocated_before_gc = 0)
REQUIRES(!process_state_update_lock_);
size_t GetPercentFree();
// Swap the allocation stack with the live stack.
void SwapStacks() REQUIRES_SHARED(Locks::mutator_lock_);
// Clear cards and update the mod union table. When process_alloc_space_cards is true,
// if clear_alloc_space_cards is true, then we clear cards instead of ageing them. We do
// not process the alloc space if process_alloc_space_cards is false.
void ProcessCards(TimingLogger* timings,
bool use_rem_sets,
bool process_alloc_space_cards,
bool clear_alloc_space_cards)
REQUIRES_SHARED(Locks::mutator_lock_);
// Push an object onto the allocation stack.
void PushOnAllocationStack(Thread* self, ObjPtr<mirror::Object>* obj)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
void PushOnAllocationStackWithInternalGC(Thread* self, ObjPtr<mirror::Object>* obj)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
EXPORT void PushOnThreadLocalAllocationStackWithInternalGC(Thread* thread,
ObjPtr<mirror::Object>* obj)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!*gc_complete_lock_, !*pending_task_lock_, !process_state_update_lock_);
void ClearPendingTrim(Thread* self) REQUIRES(!*pending_task_lock_);
void ClearPendingCollectorTransition(Thread* self) REQUIRES(!*pending_task_lock_);
// What kind of concurrency behavior is the runtime after?
bool IsGcConcurrent() const ALWAYS_INLINE {
return collector_type_ == kCollectorTypeCC ||
collector_type_ == kCollectorTypeCMC ||
collector_type_ == kCollectorTypeCMS ||
collector_type_ == kCollectorTypeCCBackground ||
collector_type_ == kCollectorTypeCMCBackground;
}
// Trim the managed and native spaces by releasing unused memory back to the OS.
void TrimSpaces(Thread* self) REQUIRES(!*gc_complete_lock_);
// Trim 0 pages at the end of reference tables.
void TrimIndirectReferenceTables(Thread* self);
template <typename Visitor>
ALWAYS_INLINE void VisitObjectsInternal(Visitor&& visitor)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::heap_bitmap_lock_, !*gc_complete_lock_);
template <typename Visitor>
ALWAYS_INLINE void VisitObjectsInternalRegionSpace(Visitor&& visitor)
REQUIRES(Locks::mutator_lock_, !Locks::heap_bitmap_lock_, !*gc_complete_lock_);
void UpdateGcCountRateHistograms() REQUIRES(gc_complete_lock_);
// GC stress mode attempts to do one GC per unique backtrace.
EXPORT void CheckGcStressMode(Thread* self, ObjPtr<mirror::Object>* obj)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!*gc_complete_lock_,
!*pending_task_lock_,
!*backtrace_lock_,
!process_state_update_lock_);
collector::GcType NonStickyGcType() const {
return HasZygoteSpace() ? collector::kGcTypePartial : collector::kGcTypeFull;
}
// Return the amount of space we allow for native memory when deciding whether to
// collect. We collect when a weighted sum of Java memory plus native memory exceeds
// the similarly weighted sum of the Java heap size target and this value.
ALWAYS_INLINE size_t NativeAllocationGcWatermark() const {
// We keep the traditional limit of max_free_ in place for small heaps,
// but allow it to be adjusted upward for large heaps to limit GC overhead.
return target_footprint_.load(std::memory_order_relaxed) / 8 + max_free_;
}
ALWAYS_INLINE void IncrementNumberOfBytesFreedRevoke(size_t freed_bytes_revoke);
// On switching app from background to foreground, grow the heap size
// to incorporate foreground heap growth multiplier.
void GrowHeapOnJankPerceptibleSwitch() REQUIRES(!process_state_update_lock_);
// Update *_freed_ever_ counters to reflect current GC values.
void IncrementFreedEver();
// Remove a vlog code from heap-inl.h which is transitively included in half the world.
EXPORT static void VlogHeapGrowth(size_t max_allowed_footprint,
size_t new_footprint,
size_t alloc_size);
// Return our best approximation of the number of bytes of native memory that
// are currently in use, and could possibly be reclaimed as an indirect result
// of a garbage collection.
size_t GetNativeBytes();
// Set concurrent_start_bytes_ to a reasonable guess, given target_footprint_ .
void SetDefaultConcurrentStartBytes() REQUIRES(!*gc_complete_lock_);
// This version assumes no concurrent updaters.
void SetDefaultConcurrentStartBytesLocked();
// All-known continuous spaces, where objects lie within fixed bounds.
std::vector<space::ContinuousSpace*> continuous_spaces_ GUARDED_BY(Locks::mutator_lock_);
// All-known discontinuous spaces, where objects may be placed throughout virtual memory.
std::vector<space::DiscontinuousSpace*> discontinuous_spaces_ GUARDED_BY(Locks::mutator_lock_);
// All-known alloc spaces, where objects may be or have been allocated.
std::vector<space::AllocSpace*> alloc_spaces_;
// A space where non-movable objects are allocated, when compaction is enabled it contains
// Classes, ArtMethods, ArtFields, and non moving objects.
space::MallocSpace* non_moving_space_;
// Space which we use for the kAllocatorTypeROSAlloc.
space::RosAllocSpace* rosalloc_space_;
// Space which we use for the kAllocatorTypeDlMalloc.
space::DlMallocSpace* dlmalloc_space_;
// The main space is the space which the GC copies to and from on process state updates. This
// space is typically either the dlmalloc_space_ or the rosalloc_space_.
space::MallocSpace* main_space_;
// The large object space we are currently allocating into.
space::LargeObjectSpace* large_object_space_;
// The card table, dirtied by the write barrier.
std::unique_ptr<accounting::CardTable> card_table_;
std::unique_ptr<accounting::ReadBarrierTable> rb_table_;
// A mod-union table remembers all of the references from the it's space to other spaces.
AllocationTrackingSafeMap<space::Space*, accounting::ModUnionTable*, kAllocatorTagHeap>
mod_union_tables_;
// A remembered set remembers all of the references from the it's space to the target space.
AllocationTrackingSafeMap<space::Space*, accounting::RememberedSet*, kAllocatorTagHeap>
remembered_sets_;
// The current collector type.
CollectorType collector_type_;
// Which collector we use when the app is in the foreground.
const CollectorType foreground_collector_type_;
// Which collector we will use when the app is notified of a transition to background.
CollectorType background_collector_type_;
// Desired collector type, heap trimming daemon transitions the heap if it is != collector_type_.
CollectorType desired_collector_type_;
// Lock which guards pending tasks.
Mutex* pending_task_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
// How many GC threads we may use for paused parts of garbage collection.
const size_t parallel_gc_threads_;
// How many GC threads we may use for unpaused parts of garbage collection.
const size_t conc_gc_threads_;
// Boolean for if we are in low memory mode.
const bool low_memory_mode_;
// If we get a pause longer than long pause log threshold, then we print out the GC after it
// finishes.
const size_t long_pause_log_threshold_;
// If we get a GC longer than long GC log threshold, then we print out the GC after it finishes.
const size_t long_gc_log_threshold_;
// Starting time of the new process; meant to be used for measuring total process CPU time.
uint64_t process_cpu_start_time_ns_;
// Last time (before and after) GC started; meant to be used to measure the
// duration between two GCs.
uint64_t pre_gc_last_process_cpu_time_ns_;
uint64_t post_gc_last_process_cpu_time_ns_;
// allocated_bytes * (current_process_cpu_time - [pre|post]_gc_last_process_cpu_time)
double pre_gc_weighted_allocated_bytes_;
double post_gc_weighted_allocated_bytes_;
// If we ignore the target footprint it lets the heap grow until it hits the heap capacity, this
// is useful for benchmarking since it reduces time spent in GC to a low %.
const bool ignore_target_footprint_;
// If we are running tests or some other configurations we might not actually
// want logs for explicit gcs since they can get spammy.
const bool always_log_explicit_gcs_;
// Lock which guards zygote space creation.
Mutex zygote_creation_lock_;
// Non-null iff we have a zygote space. Doesn't contain the large objects allocated before
// zygote space creation.
space::ZygoteSpace* zygote_space_;
// Minimum allocation size of large object.
size_t large_object_threshold_;
// Guards access to the state of GC, associated conditional variable is used to signal when a GC
// completes.
Mutex* gc_complete_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
std::unique_ptr<ConditionVariable> gc_complete_cond_ GUARDED_BY(gc_complete_lock_);
// Used to synchronize between JNI critical calls and the thread flip of the CC collector.
Mutex* thread_flip_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
std::unique_ptr<ConditionVariable> thread_flip_cond_ GUARDED_BY(thread_flip_lock_);
// This counter keeps track of how many threads are currently in a JNI critical section. This is
// incremented once per thread even with nested enters.
size_t disable_thread_flip_count_ GUARDED_BY(thread_flip_lock_);
bool thread_flip_running_ GUARDED_BY(thread_flip_lock_);
// Reference processor;
std::unique_ptr<ReferenceProcessor> reference_processor_;
// Task processor, proxies heap trim requests to the daemon threads.
std::unique_ptr<TaskProcessor> task_processor_;
// The following are declared volatile only for debugging purposes; it shouldn't otherwise
// matter.
// Collector type of the running GC.
volatile CollectorType collector_type_running_ GUARDED_BY(gc_complete_lock_);
// Cause of the last running GC.
volatile GcCause last_gc_cause_ GUARDED_BY(gc_complete_lock_);
// The thread currently running the GC.
volatile Thread* thread_running_gc_ GUARDED_BY(gc_complete_lock_);
// Last Gc type we ran. Used by WaitForConcurrentGc to know which Gc was waited on.
volatile collector::GcType last_gc_type_ GUARDED_BY(gc_complete_lock_);
collector::GcType next_gc_type_;
// Maximum size that the heap can reach.
size_t capacity_;
// The size the heap is limited to. This is initially smaller than capacity, but for largeHeap
// programs it is "cleared" making it the same as capacity.
// Only weakly enforced for simultaneous allocations.
size_t growth_limit_;
// Requested initial heap size. Temporarily ignored after a fork, but then reestablished after
// a while to usually trigger the initial GC.
size_t initial_heap_size_;
// Target size (as in maximum allocatable bytes) for the heap. Weakly enforced as a limit for
// non-concurrent GC. Used as a guideline for computing concurrent_start_bytes_ in the
// concurrent GC case. Updates normally occur while collector_type_running_ is not none.
Atomic<size_t> target_footprint_;
Mutex process_state_update_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
// Computed with foreground-multiplier in GrowForUtilization() when run in
// jank non-perceptible state. On update to process state from background to
// foreground we set target_footprint_ and concurrent_start_bytes_ to the corresponding value.
size_t min_foreground_target_footprint_ GUARDED_BY(process_state_update_lock_);
size_t min_foreground_concurrent_start_bytes_ GUARDED_BY(process_state_update_lock_);
// When num_bytes_allocated_ exceeds this amount then a concurrent GC should be requested so that
// it completes ahead of an allocation failing.
// A multiple of this is also used to determine when to trigger a GC in response to native
// allocation.
// After initialization, this is only updated by the thread that set collector_type_running_ to
// a value other than kCollectorTypeNone, or while holding gc_complete_lock, and ensuring that
// collector_type_running_ is kCollectorTypeNone.
size_t concurrent_start_bytes_;
// Since the heap was created, how many bytes have been freed.
std::atomic<int64_t> total_bytes_freed_ever_;
// Since the heap was created, how many objects have been freed.
std::atomic<uint64_t> total_objects_freed_ever_;
// Number of bytes currently allocated and not yet reclaimed. Includes active
// TLABS in their entirety, even if they have not yet been parceled out.
Atomic<size_t> num_bytes_allocated_;
// Number of registered native bytes allocated. Adjusted after each RegisterNativeAllocation and
// RegisterNativeFree. Used to help determine when to trigger GC for native allocations. Should
// not include bytes allocated through the system malloc, since those are implicitly included.
Atomic<size_t> native_bytes_registered_;
// Approximately the smallest value of GetNativeBytes() we've seen since the last GC.
Atomic<size_t> old_native_bytes_allocated_;
// Total number of native objects of which we were notified since the beginning of time, mod 2^32.
// Allows us to check for GC only roughly every kNotifyNativeInterval allocations.
Atomic<uint32_t> native_objects_notified_;
// Number of bytes freed by thread local buffer revokes. This will
// cancel out the ahead-of-time bulk counting of bytes allocated in
// rosalloc thread-local buffers. It is temporarily accumulated
// here to be subtracted from num_bytes_allocated_ later at the next
// GC.
Atomic<size_t> num_bytes_freed_revoke_;
// Records the number of bytes allocated at the time of GC, which is used later to calculate
// how many bytes have been allocated since the last GC
size_t num_bytes_alive_after_gc_;
// Info related to the current or previous GC iteration.
collector::Iteration current_gc_iteration_;
// Heap verification flags.
const bool verify_missing_card_marks_;
const bool verify_system_weaks_;
const bool verify_pre_gc_heap_;
const bool verify_pre_sweeping_heap_;
const bool verify_post_gc_heap_;
const bool verify_mod_union_table_;
bool verify_pre_gc_rosalloc_;
bool verify_pre_sweeping_rosalloc_;
bool verify_post_gc_rosalloc_;
const bool gc_stress_mode_;
// RAII that temporarily disables the rosalloc verification during
// the zygote fork.
class ScopedDisableRosAllocVerification {
private:
Heap* const heap_;
const bool orig_verify_pre_gc_;
const bool orig_verify_pre_sweeping_;
const bool orig_verify_post_gc_;
public:
explicit ScopedDisableRosAllocVerification(Heap* heap)
: heap_(heap),
orig_verify_pre_gc_(heap_->verify_pre_gc_rosalloc_),
orig_verify_pre_sweeping_(heap_->verify_pre_sweeping_rosalloc_),
orig_verify_post_gc_(heap_->verify_post_gc_rosalloc_) {
heap_->verify_pre_gc_rosalloc_ = false;
heap_->verify_pre_sweeping_rosalloc_ = false;
heap_->verify_post_gc_rosalloc_ = false;
}
~ScopedDisableRosAllocVerification() {
heap_->verify_pre_gc_rosalloc_ = orig_verify_pre_gc_;
heap_->verify_pre_sweeping_rosalloc_ = orig_verify_pre_sweeping_;
heap_->verify_post_gc_rosalloc_ = orig_verify_post_gc_;
}
};
// Parallel GC data structures.
std::unique_ptr<ThreadPool> thread_pool_;
// A bitmap that is set corresponding to the known live objects since the last GC cycle.
std::unique_ptr<accounting::HeapBitmap> live_bitmap_ GUARDED_BY(Locks::heap_bitmap_lock_);
// A bitmap that is set corresponding to the marked objects in the current GC cycle.
std::unique_ptr<accounting::HeapBitmap> mark_bitmap_ GUARDED_BY(Locks::heap_bitmap_lock_);
// Mark stack that we reuse to avoid re-allocating the mark stack.
std::unique_ptr<accounting::ObjectStack> mark_stack_;
// Allocation stack, new allocations go here so that we can do sticky mark bits. This enables us
// to use the live bitmap as the old mark bitmap.
const size_t max_allocation_stack_size_;
std::unique_ptr<accounting::ObjectStack> allocation_stack_;
// Second allocation stack so that we can process allocation with the heap unlocked.
std::unique_ptr<accounting::ObjectStack> live_stack_;
// Allocator type.
AllocatorType current_allocator_;
const AllocatorType current_non_moving_allocator_;
// Which GCs we run in order when an allocation fails.
std::vector<collector::GcType> gc_plan_;
// Bump pointer spaces.
space::BumpPointerSpace* bump_pointer_space_;
// Temp space is the space which the semispace collector copies to.
space::BumpPointerSpace* temp_space_;
// Region space, used by the concurrent collector.
space::RegionSpace* region_space_;
// Minimum free guarantees that you always have at least min_free_ free bytes after growing for
// utilization, regardless of target utilization ratio.
const size_t min_free_;
// The ideal maximum free size, when we grow the heap for utilization.
const size_t max_free_;
// Target ideal heap utilization ratio.
double target_utilization_;
// How much more we grow the heap when we are a foreground app instead of background.
double foreground_heap_growth_multiplier_;
// The amount of native memory allocation since the last GC required to cause us to wait for a
// collection as a result of native allocation. Very large values can cause the device to run
// out of memory, due to lack of finalization to reclaim native memory. Making it too small can
// cause jank in apps like launcher that intentionally allocate large amounts of memory in rapid
// succession. (b/122099093) 1/4 to 1/3 of physical memory seems to be a good number.
const size_t stop_for_native_allocs_;
// Total time which mutators are paused or waiting for GC to complete.
uint64_t total_wait_time_;
// The current state of heap verification, may be enabled or disabled.
VerifyObjectMode verify_object_mode_;
// Compacting GC disable count, prevents compacting GC from running iff > 0.
size_t disable_moving_gc_count_ GUARDED_BY(gc_complete_lock_);
std::vector<collector::GarbageCollector*> garbage_collectors_;
collector::SemiSpace* semi_space_collector_;
collector::MarkCompact* mark_compact_;
Atomic<collector::ConcurrentCopying*> active_concurrent_copying_collector_;
collector::ConcurrentCopying* young_concurrent_copying_collector_;
collector::ConcurrentCopying* concurrent_copying_collector_;
const bool is_running_on_memory_tool_;
const bool use_tlab_;
// Pointer to the space which becomes the new main space when we do homogeneous space compaction.
// Use unique_ptr since the space is only added during the homogeneous compaction phase.
std::unique_ptr<space::MallocSpace> main_space_backup_;
// Minimal interval allowed between two homogeneous space compactions caused by OOM.
uint64_t min_interval_homogeneous_space_compaction_by_oom_;
// Times of the last homogeneous space compaction caused by OOM.
uint64_t last_time_homogeneous_space_compaction_by_oom_;
// Saved OOMs by homogeneous space compaction.
Atomic<size_t> count_delayed_oom_;
// Count for requested homogeneous space compaction.
Atomic<size_t> count_requested_homogeneous_space_compaction_;
// Count for ignored homogeneous space compaction.
Atomic<size_t> count_ignored_homogeneous_space_compaction_;
// Count for performed homogeneous space compaction.
Atomic<size_t> count_performed_homogeneous_space_compaction_;
// The number of garbage collections (either young or full, not trims or the like) we have
// completed since heap creation. We include requests that turned out to be impossible
// because they were disabled. We guard against wrapping, though that's unlikely.
// Increment is guarded by gc_complete_lock_.
Atomic<uint32_t> gcs_completed_;
// The number of the last garbage collection that has been requested. A value of gcs_completed
// + 1 indicates that another collection is needed or in progress. A value of gcs_completed_ or
// (logically) less means that no new GC has been requested.
Atomic<uint32_t> max_gc_requested_;
// Active tasks which we can modify (change target time, desired collector type, etc..).
CollectorTransitionTask* pending_collector_transition_ GUARDED_BY(pending_task_lock_);
HeapTrimTask* pending_heap_trim_ GUARDED_BY(pending_task_lock_);
// Whether or not we use homogeneous space compaction to avoid OOM errors.
bool use_homogeneous_space_compaction_for_oom_;
// If true, enable generational collection when using the Concurrent Copying
// (CC) collector, i.e. use sticky-bit CC for minor collections and (full) CC
// for major collections. Set in Heap constructor.
const bool use_generational_cc_;
// True if the currently running collection has made some thread wait.
bool running_collection_is_blocking_ GUARDED_BY(gc_complete_lock_);
// The number of blocking GC runs.
uint64_t blocking_gc_count_;
// The total duration of blocking GC runs.
uint64_t blocking_gc_time_;
// The duration of the window for the GC count rate histograms.
static constexpr uint64_t kGcCountRateHistogramWindowDuration = MsToNs(10 * 1000); // 10s.
// Maximum number of missed histogram windows for which statistics will be collected.
static constexpr uint64_t kGcCountRateHistogramMaxNumMissedWindows = 100;
// The last time when the GC count rate histograms were updated.
// This is rounded by kGcCountRateHistogramWindowDuration (a multiple of 10s).
uint64_t last_update_time_gc_count_rate_histograms_;
// The running count of GC runs in the last window.
uint64_t gc_count_last_window_;
// The running count of blocking GC runs in the last window.
uint64_t blocking_gc_count_last_window_;
// The maximum number of buckets in the GC count rate histograms.
static constexpr size_t kGcCountRateMaxBucketCount = 200;
// The histogram of the number of GC invocations per window duration.
Histogram<uint64_t> gc_count_rate_histogram_ GUARDED_BY(gc_complete_lock_);
// The histogram of the number of blocking GC invocations per window duration.
Histogram<uint64_t> blocking_gc_count_rate_histogram_ GUARDED_BY(gc_complete_lock_);
// Allocation tracking support
Atomic<bool> alloc_tracking_enabled_;
std::unique_ptr<AllocRecordObjectMap> allocation_records_;
size_t alloc_record_depth_;
// Perfetto Java Heap Profiler support.
HeapSampler heap_sampler_;
// GC stress related data structures.
Mutex* backtrace_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
// Debugging variables, seen backtraces vs unique backtraces.
Atomic<uint64_t> seen_backtrace_count_;
Atomic<uint64_t> unique_backtrace_count_;
// Stack trace hashes that we already saw,
std::unordered_set<uint64_t> seen_backtraces_ GUARDED_BY(backtrace_lock_);
// We disable GC when we are shutting down the runtime in case there are daemon threads still
// allocating.
bool gc_disabled_for_shutdown_ GUARDED_BY(gc_complete_lock_);
// Turned on by -XX:DumpRegionInfoBeforeGC and -XX:DumpRegionInfoAfterGC to
// emit region info before and after each GC cycle.
bool dump_region_info_before_gc_;
bool dump_region_info_after_gc_;
// Boot image spaces.
std::vector<space::ImageSpace*> boot_image_spaces_;
// Boot image address range. Includes images and oat files.
uint32_t boot_images_start_address_;
uint32_t boot_images_size_;
// The number of times we initiated a GC of last resort to try to avoid an OOME.
Atomic<uint64_t> pre_oome_gc_count_;
// An installed allocation listener.
Atomic<AllocationListener*> alloc_listener_;
// An installed GC Pause listener.
Atomic<GcPauseListener*> gc_pause_listener_;
std::unique_ptr<Verification> verification_;
friend class CollectorTransitionTask;
friend class collector::GarbageCollector;
friend class collector::ConcurrentCopying;
friend class collector::MarkCompact;
friend class collector::MarkSweep;
friend class collector::SemiSpace;
friend class GCCriticalSection;
friend class ReferenceQueue;
friend class ScopedGCCriticalSection;
friend class ScopedInterruptibleGCCriticalSection;
friend class VerifyReferenceCardVisitor;
friend class VerifyReferenceVisitor;
friend class VerifyObjectVisitor;
DISALLOW_IMPLICIT_CONSTRUCTORS(Heap);
};
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_HEAP_H_