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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 <iosfwd>
#include <string>
#include <vector>
#include "atomic_integer.h"
#include "base/timing_logger.h"
#include "gc/accounting/atomic_stack.h"
#include "gc/accounting/card_table.h"
#include "gc/collector/gc_type.h"
#include "gc/collector_type.h"
#include "globals.h"
#include "gtest/gtest.h"
#include "jni.h"
#include "locks.h"
#include "offsets.h"
#include "reference_queue.h"
#include "root_visitor.h"
#include "safe_map.h"
#include "thread_pool.h"
namespace art {
class ConditionVariable;
class Mutex;
class StackVisitor;
class Thread;
class TimingLogger;
namespace mirror {
class Class;
class Object;
} // namespace mirror
namespace gc {
namespace accounting {
class HeapBitmap;
class ModUnionTable;
class SpaceSetMap;
} // namespace accounting
namespace collector {
class GarbageCollector;
class MarkSweep;
class SemiSpace;
} // namespace collector
namespace space {
class AllocSpace;
class BumpPointerSpace;
class DiscontinuousSpace;
class DlMallocSpace;
class ImageSpace;
class LargeObjectSpace;
class MallocSpace;
class RosAllocSpace;
class Space;
class SpaceTest;
class ContinuousMemMapAllocSpace;
} // namespace space
class AgeCardVisitor {
public:
byte operator()(byte card) const {
if (card == accounting::CardTable::kCardDirty) {
return card - 1;
} else {
return 0;
}
}
};
// Different types of allocators.
enum AllocatorType {
kAllocatorTypeBumpPointer,
kAllocatorTypeFreeList, // ROSAlloc / dlmalloc
kAllocatorTypeLOS, // Large object space.
};
// What caused the GC?
enum GcCause {
// GC triggered by a failed allocation. Thread doing allocation is blocked waiting for GC before
// retrying allocation.
kGcCauseForAlloc,
// A background GC trying to ensure there is free memory ahead of allocations.
kGcCauseBackground,
// An explicit System.gc() call.
kGcCauseExplicit,
};
std::ostream& operator<<(std::ostream& os, const GcCause& policy);
// How we want to sanity check the heap's correctness.
enum HeapVerificationMode {
kHeapVerificationNotPermitted, // Too early in runtime start-up for heap to be verified.
kNoHeapVerification, // Production default.
kVerifyAllFast, // Sanity check all heap accesses with quick(er) tests.
kVerifyAll // Sanity check all heap accesses.
};
static constexpr HeapVerificationMode kDesiredHeapVerification = kNoHeapVerification;
// If true, use rosalloc/RosAllocSpace instead of dlmalloc/DlMallocSpace
static constexpr bool kUseRosAlloc = true;
// The process state passed in from the activity manager, used to determine when to do trimming
// and compaction.
enum ProcessState {
kProcessStateJankPerceptible = 0,
kProcessStateJankImperceptible = 1,
};
// If true, measure the total allocation time.
static constexpr bool kMeasureAllocationTime = false;
// Primitive arrays larger than this size are put in the large object space.
static constexpr size_t kLargeObjectThreshold = 3 * kPageSize;
class Heap {
public:
// If true, measure the total allocation time.
static constexpr bool kMeasureAllocationTime = false;
// Primitive arrays larger than this size are put in the large object space.
static constexpr size_t kLargeObjectThreshold = 3 * kPageSize;
static constexpr size_t kDefaultInitialSize = 2 * MB;
static constexpr size_t kDefaultMaximumSize = 32 * MB;
static constexpr size_t kDefaultMaxFree = 2 * MB;
static constexpr size_t kDefaultMinFree = kDefaultMaxFree / 4;
static constexpr size_t kDefaultLongPauseLogThreshold = MsToNs(5);
static constexpr size_t kDefaultLongGCLogThreshold = MsToNs(100);
// Default target utilization.
static constexpr double kDefaultTargetUtilization = 0.5;
// Used so that we don't overflow the allocation time atomic integer.
static constexpr size_t kTimeAdjust = 1024;
// 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 initial_size, size_t growth_limit, size_t min_free,
size_t max_free, double target_utilization, size_t capacity,
const std::string& original_image_file_name, CollectorType collector_type_,
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_max_footprint);
~Heap();
// Allocates and initializes storage for an object instance.
template <const bool kInstrumented>
inline mirror::Object* AllocObject(Thread* self, mirror::Class* klass, size_t num_bytes)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return AllocObjectWithAllocator<kInstrumented>(self, klass, num_bytes, GetCurrentAllocator());
}
template <const bool kInstrumented>
inline mirror::Object* AllocNonMovableObject(Thread* self, mirror::Class* klass,
size_t num_bytes)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return AllocObjectWithAllocator<kInstrumented>(self, klass, num_bytes,
GetCurrentNonMovingAllocator());
}
template <bool kInstrumented, typename PreFenceVisitor = VoidFunctor>
ALWAYS_INLINE mirror::Object* AllocObjectWithAllocator(
Thread* self, mirror::Class* klass, size_t byte_count, AllocatorType allocator,
const PreFenceVisitor& pre_fence_visitor = VoidFunctor())
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
AllocatorType GetCurrentAllocator() const {
return current_allocator_;
}
AllocatorType GetCurrentNonMovingAllocator() const {
return current_non_moving_allocator_;
}
// Visit all of the live objects in the heap.
void VisitObjects(ObjectVisitorCallback callback, void* arg)
SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_);
void SwapSemiSpaces() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
void DebugCheckPreconditionsForAllocObject(mirror::Class* c, size_t byte_count)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void ThrowOutOfMemoryError(size_t byte_count, bool large_object_allocation);
void RegisterNativeAllocation(JNIEnv* env, int bytes);
void RegisterNativeFree(JNIEnv* env, int bytes);
// Change the allocator, updates entrypoints.
void ChangeAllocator(AllocatorType allocator);
// Change the collector to be one of the possible options (MS, CMS, SS).
void ChangeCollector(CollectorType collector_type);
// The given reference is believed to be to an object in the Java heap, check the soundness of it.
void VerifyObjectImpl(const mirror::Object* o);
void VerifyObject(const mirror::Object* o) {
if (o != nullptr && this != nullptr && verify_object_mode_ > kNoHeapVerification) {
VerifyObjectImpl(o);
}
}
// Check sanity of all live references.
void VerifyHeap() LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
bool VerifyHeapReferences()
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool VerifyMissingCardMarks()
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(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 mirror::Object* obj) const;
// Returns true if the address passed in is a heap address, doesn't need to be aligned.
bool IsHeapAddress(const mirror::Object* obj) const;
// 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 mirror::Object* obj, bool search_allocation_stack = true,
bool search_live_stack = true, bool sorted = false)
SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
// Returns true if there is any chance that the object (obj) will move.
bool IsMovableObject(const mirror::Object* obj) const;
// Returns true if an object is in the temp space, if this happens its usually indicative of
// compaction related errors.
bool IsInTempSpace(const mirror::Object* obj) const;
// Enables us to prevent GC until objects are released.
void IncrementDisableGC(Thread* self);
void DecrementDisableGC(Thread* self);
// Initiates an explicit garbage collection.
void CollectGarbage(bool clear_soft_references) LOCKS_EXCLUDED(Locks::mutator_lock_);
// Does a concurrent GC, should only be called by the GC daemon thread
// through runtime.
void ConcurrentGC(Thread* self) LOCKS_EXCLUDED(Locks::runtime_shutdown_lock_);
// Implements VMDebug.countInstancesOfClass and JDWP VM_InstanceCount.
// The boolean decides whether to use IsAssignableFrom or == when comparing classes.
void CountInstances(const std::vector<mirror::Class*>& classes, bool use_is_assignable_from,
uint64_t* counts)
LOCKS_EXCLUDED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Implements JDWP RT_Instances.
void GetInstances(mirror::Class* c, int32_t max_count, std::vector<mirror::Object*>& instances)
LOCKS_EXCLUDED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Implements JDWP OR_ReferringObjects.
void GetReferringObjects(mirror::Object* o, int32_t max_count, std::vector<mirror::Object*>& referring_objects)
LOCKS_EXCLUDED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(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();
// 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 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.
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.
collector::GcType WaitForGcToComplete(Thread* self) LOCKS_EXCLUDED(gc_complete_lock_);
// Update the heap's process state to a new value, may cause compaction to occur.
void UpdateProcessState(ProcessState process_state);
const std::vector<space::ContinuousSpace*>& GetContinuousSpaces() const {
return continuous_spaces_;
}
const std::vector<space::DiscontinuousSpace*>& GetDiscontinuousSpaces() const {
return discontinuous_spaces_;
}
void SetReferenceOffsets(MemberOffset reference_referent_offset,
MemberOffset reference_queue_offset,
MemberOffset reference_queueNext_offset,
MemberOffset reference_pendingNext_offset,
MemberOffset finalizer_reference_zombie_offset);
MemberOffset GetReferenceReferentOffset() const {
return reference_referent_offset_;
}
MemberOffset GetReferenceQueueOffset() const {
return reference_queue_offset_;
}
MemberOffset GetReferenceQueueNextOffset() const {
return reference_queueNext_offset_;
}
MemberOffset GetReferencePendingNextOffset() const {
return reference_pendingNext_offset_;
}
MemberOffset GetFinalizerReferenceZombieOffset() const {
return finalizer_reference_zombie_offset_;
}
static mirror::Object* PreserveSoftReferenceCallback(mirror::Object* obj, void* arg);
void ProcessReferences(TimingLogger& timings, bool clear_soft, RootVisitor* is_marked_callback,
RootVisitor* recursive_mark_object_callback, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
// Enable verification of object references when the runtime is sufficiently initialized.
void EnableObjectValidation() {
verify_object_mode_ = kDesiredHeapVerification;
if (verify_object_mode_ > kNoHeapVerification) {
VerifyHeap();
}
}
// Disable object reference verification for image writing.
void DisableObjectValidation() {
verify_object_mode_ = kHeapVerificationNotPermitted;
}
// Other checks may be performed if we know the heap should be in a sane state.
bool IsObjectValidationEnabled() const {
return kDesiredHeapVerification > kNoHeapVerification &&
verify_object_mode_ > kHeapVerificationNotPermitted;
}
// Returns true if low memory mode is enabled.
bool IsLowMemoryMode() const {
return low_memory_mode_;
}
void RecordFree(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 mirror::Object* dst, MemberOffset /*offset*/, const mirror::Object* /*new_value*/) {
card_table_->MarkCard(dst);
}
// Write barrier for array operations that update many field positions
void WriteBarrierArray(const mirror::Object* dst, int /*start_offset*/,
size_t /*length TODO: element_count or byte_count?*/) {
card_table_->MarkCard(dst);
}
void WriteBarrierEveryFieldOf(const mirror::Object* obj) {
card_table_->MarkCard(obj);
}
accounting::CardTable* GetCardTable() const {
return card_table_.get();
}
void AddFinalizerReference(Thread* self, mirror::Object* object);
// Returns the number of bytes currently allocated.
size_t GetBytesAllocated() const {
return num_bytes_allocated_;
}
// Returns the number of objects currently allocated.
size_t GetObjectsAllocated() const LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
// Returns the total number of objects allocated since the heap was created.
size_t GetObjectsAllocatedEver() const;
// Returns the total number of bytes allocated since the heap was created.
size_t GetBytesAllocatedEver() const;
// Returns the total number of objects freed since the heap was created.
size_t GetObjectsFreedEver() const {
return total_objects_freed_ever_;
}
// Returns the total number of bytes freed since the heap was created.
size_t GetBytesFreedEver() const {
return total_bytes_freed_ever_;
}
// 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.
int64_t GetMaxMemory() const {
return growth_limit_;
}
// Implements java.lang.Runtime.totalMemory, returning the amount of memory consumed by an
// application.
int64_t GetTotalMemory() const;
// Implements java.lang.Runtime.freeMemory.
int64_t GetFreeMemory() const {
return GetTotalMemory() - num_bytes_allocated_;
}
// 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.
space::ContinuousSpace* FindContinuousSpaceFromObject(const mirror::Object*, bool fail_ok) const;
space::DiscontinuousSpace* FindDiscontinuousSpaceFromObject(const mirror::Object*,
bool fail_ok) const;
space::Space* FindSpaceFromObject(const mirror::Object*, bool fail_ok) const;
void DumpForSigQuit(std::ostream& os);
// Trim the managed and native heaps by releasing unused memory back to the OS.
void Trim();
void RevokeThreadLocalBuffers(Thread* thread);
void RevokeAllThreadLocalBuffers();
accounting::HeapBitmap* GetLiveBitmap() SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
return live_bitmap_.get();
}
accounting::HeapBitmap* GetMarkBitmap() SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
return mark_bitmap_.get();
}
accounting::ObjectStack* GetLiveStack() SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
return live_stack_.get();
}
void PreZygoteFork() NO_THREAD_SAFETY_ANALYSIS;
// Mark and empty stack.
void FlushAllocStack()
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
// Mark all the objects in the allocation stack in the specified bitmap.
void MarkAllocStack(accounting::SpaceBitmap* bitmap, accounting::SpaceSetMap* large_objects,
accounting::ObjectStack* stack)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
// Mark the specified allocation stack as live.
void MarkAllocStackAsLive(accounting::ObjectStack* stack)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
// DEPRECATED: Should remove in "near" future when support for multiple image spaces is added.
// Assumes there is only one image space.
space::ImageSpace* GetImageSpace() const;
space::MallocSpace* GetNonMovingSpace() const {
return non_moving_space_;
}
space::LargeObjectSpace* GetLargeObjectsSpace() const {
return large_object_space_;
}
void DumpSpaces(std::ostream& stream = LOG(INFO));
// GC performance measuring
void DumpGcPerformanceInfo(std::ostream& os);
// Returns true if we currently care about pause times.
bool CareAboutPauseTimes() const {
return process_state_ == kProcessStateJankPerceptible;
}
// Thread pool.
void CreateThreadPool();
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);
bool IsCompilingBoot() const;
bool HasImageSpace() const;
private:
void Compact(space::ContinuousMemMapAllocSpace* target_space,
space::ContinuousMemMapAllocSpace* source_space);
static bool AllocatorHasAllocationStack(AllocatorType allocator_type) {
return allocator_type != kAllocatorTypeBumpPointer;
}
static bool AllocatorHasConcurrentGC(AllocatorType allocator_type) {
return allocator_type != kAllocatorTypeBumpPointer;
}
bool ShouldAllocLargeObject(mirror::Class* c, size_t byte_count) const;
ALWAYS_INLINE void CheckConcurrentGC(Thread* self, size_t new_num_bytes_allocated,
mirror::Object* obj);
// Handles Allocate()'s slow allocation path with GC involved after
// an initial allocation attempt failed.
mirror::Object* AllocateInternalWithGc(Thread* self, AllocatorType allocator, size_t num_bytes,
size_t* bytes_allocated)
LOCKS_EXCLUDED(Locks::thread_suspend_count_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Allocate into a specific space.
mirror::Object* AllocateInto(Thread* self, space::AllocSpace* space, mirror::Class* c,
size_t bytes)
SHARED_LOCKS_REQUIRED(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>
ALWAYS_INLINE mirror::Object* TryToAllocate(Thread* self, AllocatorType allocator_type,
size_t alloc_size, bool grow,
size_t* bytes_allocated)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void ThrowOutOfMemoryError(Thread* self, size_t byte_count, bool large_object_allocation)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool IsOutOfMemoryOnAllocation(size_t alloc_size, bool grow);
// Pushes a list of cleared references out to the managed heap.
void SetReferenceReferent(mirror::Object* reference, mirror::Object* referent)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
mirror::Object* GetReferenceReferent(mirror::Object* reference)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void ClearReferenceReferent(mirror::Object* reference)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
SetReferenceReferent(reference, nullptr);
}
void EnqueueClearedReferences();
// Returns true if the reference object has not yet been enqueued.
bool IsEnqueuable(const mirror::Object* ref) const;
bool IsEnqueued(mirror::Object* ref) const;
void DelayReferenceReferent(mirror::Class* klass, mirror::Object* obj, RootVisitor mark_visitor,
void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Run the finalizers.
void RunFinalization(JNIEnv* env);
// Blocks the caller until the garbage collector becomes idle and returns the type of GC we
// waited for.
collector::GcType WaitForGcToCompleteLocked(Thread* self)
EXCLUSIVE_LOCKS_REQUIRED(gc_complete_lock_);
void RequestHeapTrim() LOCKS_EXCLUDED(Locks::runtime_shutdown_lock_);
void RequestConcurrentGC(Thread* self) LOCKS_EXCLUDED(Locks::runtime_shutdown_lock_);
bool IsGCRequestPending() const;
size_t RecordAllocationInstrumented(size_t size, mirror::Object* object)
LOCKS_EXCLUDED(GlobalSynchronization::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
size_t RecordAllocationUninstrumented(size_t size, mirror::Object* object)
LOCKS_EXCLUDED(GlobalSynchronization::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Sometimes CollectGarbageInternal decides to run a different Gc than you requested. Returns
// which type of Gc was actually ran.
collector::GcType CollectGarbageInternal(collector::GcType gc_plan, GcCause gc_cause,
bool clear_soft_references)
LOCKS_EXCLUDED(gc_complete_lock_,
Locks::heap_bitmap_lock_,
Locks::thread_suspend_count_lock_);
void PreGcVerification(collector::GarbageCollector* gc);
void PreSweepingGcVerification(collector::GarbageCollector* gc)
EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
void PostGcVerification(collector::GarbageCollector* gc)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Update the watermark for the native allocated bytes based on the current number of native
// bytes allocated and the target utilization ratio.
void UpdateMaxNativeFootprint();
// 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(collector::GcType gc_type, uint64_t gc_duration);
size_t GetPercentFree();
void AddSpace(space::Space* space) LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
// No thread saftey analysis since we call this everywhere and it is impossible to find a proper
// lock ordering for it.
void VerifyObjectBody(const mirror::Object *obj) NO_THREAD_SAFETY_ANALYSIS;
static void VerificationCallback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(GlobalSychronization::heap_bitmap_lock_);
// Swap the allocation stack with the live stack.
void SwapStacks();
// Clear cards and update the mod union table.
void ProcessCards(TimingLogger& timings);
// All-known continuous spaces, where objects lie within fixed bounds.
std::vector<space::ContinuousSpace*> continuous_spaces_;
// All-known discontinuous spaces, where objects may be placed throughout virtual memory.
std::vector<space::DiscontinuousSpace*> discontinuous_spaces_;
// 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_;
// The large object space we are currently allocating into.
space::LargeObjectSpace* large_object_space_;
// The card table, dirtied by the write barrier.
UniquePtr<accounting::CardTable> card_table_;
// A mod-union table remembers all of the references from the it's space to other spaces.
SafeMap<space::Space*, accounting::ModUnionTable*> mod_union_tables_;
// What kind of concurrency behavior is the runtime after? True for concurrent mark sweep GC,
// false for stop-the-world mark sweep.
const bool concurrent_gc_;
// The current collector type.
CollectorType collector_type_;
// 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_;
// If we ignore the max 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_max_footprint_;
// If we have a zygote space.
bool have_zygote_space_;
// Number of pinned primitive arrays in the movable space.
// Block all GC until this hits zero, or we hit the timeout!
size_t number_gc_blockers_;
static constexpr size_t KGCBlockTimeout = 30000;
// 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;
UniquePtr<ConditionVariable> gc_complete_cond_ GUARDED_BY(gc_complete_lock_);
// Reference queues.
ReferenceQueue soft_reference_queue_;
ReferenceQueue weak_reference_queue_;
ReferenceQueue finalizer_reference_queue_;
ReferenceQueue phantom_reference_queue_;
ReferenceQueue cleared_references_;
// True while the garbage collector is running.
volatile bool is_gc_running_ 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.
const 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.
size_t growth_limit_;
// When the number of bytes allocated exceeds the footprint TryAllocate returns NULL indicating
// a GC should be triggered.
size_t max_allowed_footprint_;
// The watermark at which a concurrent GC is requested by registerNativeAllocation.
size_t native_footprint_gc_watermark_;
// The watermark at which a GC is performed inside of registerNativeAllocation.
size_t native_footprint_limit_;
// Whether or not we need to run finalizers in the next native allocation.
bool native_need_to_run_finalization_;
// Activity manager members.
jclass activity_thread_class_;
jclass application_thread_class_;
jobject activity_thread_;
jobject application_thread_;
jfieldID last_process_state_id_;
// Whether or not we currently care about pause times.
ProcessState process_state_;
// When num_bytes_allocated_ exceeds this amount then a concurrent GC should be requested so that
// it completes ahead of an allocation failing.
size_t concurrent_start_bytes_;
// Since the heap was created, how many bytes have been freed.
size_t total_bytes_freed_ever_;
// Since the heap was created, how many objects have been freed.
size_t total_objects_freed_ever_;
// Number of bytes allocated. Adjusted after each allocation and free.
AtomicInteger num_bytes_allocated_;
// Bytes which are allocated and managed by native code but still need to be accounted for.
AtomicInteger native_bytes_allocated_;
// Data structure GC overhead.
AtomicInteger gc_memory_overhead_;
// Heap verification flags.
const bool verify_missing_card_marks_;
const bool verify_system_weaks_;
const bool verify_pre_gc_heap_;
const bool verify_post_gc_heap_;
const bool verify_mod_union_table_;
// Parallel GC data structures.
UniquePtr<ThreadPool> thread_pool_;
// Sticky mark bits GC has some overhead, so if we have less a few megabytes of AllocSpace then
// it's probably better to just do a partial GC.
const size_t min_alloc_space_size_for_sticky_gc_;
// Minimum remaining size for sticky GC. Since sticky GC doesn't free up as much memory as a
// normal GC, it is important to not use it when we are almost out of memory.
const size_t min_remaining_space_for_sticky_gc_;
// The last time a heap trim occurred.
uint64_t last_trim_time_ms_;
// The nanosecond time at which the last GC ended.
uint64_t last_gc_time_ns_;
// How many bytes were allocated at the end of the last GC.
uint64_t last_gc_size_;
// Estimated allocation rate (bytes / second). Computed between the time of the last GC cycle
// and the start of the current one.
uint64_t allocation_rate_;
// For a GC cycle, a bitmap that is set corresponding to the
UniquePtr<accounting::HeapBitmap> live_bitmap_ GUARDED_BY(Locks::heap_bitmap_lock_);
UniquePtr<accounting::HeapBitmap> mark_bitmap_ GUARDED_BY(Locks::heap_bitmap_lock_);
// Mark stack that we reuse to avoid re-allocating the mark stack.
UniquePtr<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_;
UniquePtr<accounting::ObjectStack> allocation_stack_;
// Second allocation stack so that we can process allocation with the heap unlocked.
UniquePtr<accounting::ObjectStack> live_stack_;
// Allocator type.
AllocatorType current_allocator_;
const AllocatorType current_non_moving_allocator_;
// Which GCs we run in order when we 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_;
// 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_;
// Minimum free guarantees that you always have at least min_free_ free bytes after growing for
// utilization, regardless of target utilization ratio.
size_t min_free_;
// The ideal maximum free size, when we grow the heap for utilization.
size_t max_free_;
// Target ideal heap utilization ratio
double target_utilization_;
// Total time which mutators are paused or waiting for GC to complete.
uint64_t total_wait_time_;
// Total number of objects allocated in microseconds.
AtomicInteger total_allocation_time_;
// The current state of heap verification, may be enabled or disabled.
HeapVerificationMode verify_object_mode_;
// GC disable count, error on GC if > 0.
size_t gc_disable_count_ GUARDED_BY(gc_complete_lock_);
std::vector<collector::GarbageCollector*> garbage_collectors_;
collector::SemiSpace* semi_space_collector_;
const bool running_on_valgrind_;
friend class collector::MarkSweep;
friend class collector::SemiSpace;
friend class ReferenceQueue;
friend class VerifyReferenceCardVisitor;
friend class VerifyReferenceVisitor;
friend class VerifyObjectVisitor;
friend class ScopedHeapLock;
friend class space::SpaceTest;
class AllocationTimer {
private:
Heap* heap_;
mirror::Object** allocated_obj_ptr_;
uint64_t allocation_start_time_;
public:
AllocationTimer(Heap* heap, mirror::Object** allocated_obj_ptr);
~AllocationTimer();
};
DISALLOW_IMPLICIT_CONSTRUCTORS(Heap);
};
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_HEAP_H_