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// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_HEAP_CONCURRENT_MARKING_H_
#define V8_HEAP_CONCURRENT_MARKING_H_
#include <memory>
#include "include/v8-platform.h"
#include "src/base/atomic-utils.h"
#include "src/base/functional.h"
#include "src/base/optional.h"
#include "src/base/platform/condition-variable.h"
#include "src/base/platform/mutex.h"
#include "src/heap/marking-visitor.h"
#include "src/heap/marking-worklist.h"
#include "src/heap/memory-measurement.h"
#include "src/heap/slot-set.h"
#include "src/heap/spaces.h"
#include "src/heap/young-generation-marking-visitor.h"
#include "src/init/v8.h"
#include "src/tasks/cancelable-task.h"
#include "src/utils/allocation.h"
#include "src/utils/utils.h"
namespace v8 {
namespace internal {
class Heap;
class Isolate;
class NonAtomicMarkingState;
class MemoryChunk;
class WeakObjects;
struct MemoryChunkData {
intptr_t live_bytes;
std::unique_ptr<TypedSlots> typed_slots;
};
// This class is a wrapper around an unordered_map that defines the minimum
// interface to be usable in marking. It aims to provide faster access in the
// common case where the requested element is the same as the one previously
// tried.
class MemoryChunkDataMap final {
using MemoryChunkDataMapT = std::unordered_map<MemoryChunk*, MemoryChunkData,
base::hash<MemoryChunk*>>;
public:
MemoryChunkDataMapT::mapped_type& operator[](
const MemoryChunkDataMapT::key_type& key) {
// nullptr value is used to indicate absence of a last key.
DCHECK_NOT_NULL(key);
if (key == last_key_) {
return *last_mapped_;
}
auto it = map_.find(key);
if (it == map_.end()) {
auto result = map_.emplace(key, MemoryChunkData());
DCHECK(result.second);
it = result.first;
}
last_key_ = key;
last_mapped_ = &it->second;
return it->second;
}
MemoryChunkDataMapT::size_type erase(
const MemoryChunkDataMapT::key_type& key) {
last_key_ = nullptr;
last_mapped_ = nullptr;
return map_.erase(key);
}
// No iterator is cached in this class so an actual find() has to be executed
// everytime.
MemoryChunkDataMapT::iterator find(const MemoryChunkDataMapT::key_type& key) {
return map_.find(key);
}
MemoryChunkDataMapT::iterator begin() { return map_.begin(); }
MemoryChunkDataMapT::const_iterator end() { return map_.end(); }
void clear() {
last_key_ = nullptr;
last_mapped_ = nullptr;
map_.clear();
}
bool empty() const { return map_.empty(); }
private:
MemoryChunkDataMapT::key_type last_key_ = nullptr;
MemoryChunkDataMapT::mapped_type* last_mapped_ = nullptr;
MemoryChunkDataMapT map_;
};
class V8_EXPORT_PRIVATE ConcurrentMarking {
public:
// When the scope is entered, the concurrent marking tasks
// are preempted and are not looking at the heap objects, concurrent marking
// is resumed when the scope is exited.
class V8_NODISCARD PauseScope {
public:
explicit PauseScope(ConcurrentMarking* concurrent_marking);
~PauseScope();
private:
ConcurrentMarking* const concurrent_marking_;
const bool resume_on_exit_;
};
ConcurrentMarking(Heap* heap, WeakObjects* weak_objects);
~ConcurrentMarking();
// Schedules asynchronous job to perform concurrent marking at |priority|.
// Objects in the heap should not be moved while these are active (can be
// stopped safely via Stop() or PauseScope).
void TryScheduleJob(GarbageCollector garbage_collector,
TaskPriority priority = TaskPriority::kUserVisible);
// Waits for scheduled job to complete.
void Join();
// Preempts ongoing job ASAP. Returns true if concurrent marking was in
// progress, false otherwise.
bool Pause();
// Schedules asynchronous job to perform concurrent marking at |priority| if
// not already running, otherwise adjusts the number of workers running job
// and the priority if different from the default kUserVisible.
void RescheduleJobIfNeeded(
GarbageCollector garbage_collector,
TaskPriority priority = TaskPriority::kUserVisible);
// Flushes native context sizes to the given table of the main thread.
void FlushNativeContexts(NativeContextStats* main_stats);
// Flushes memory chunk data.
void FlushMemoryChunkData();
// This function is called for a new space page that was cleared after
// scavenge and is going to be re-used.
void ClearMemoryChunkData(MemoryChunk* chunk);
// Flushes pretenuring feedback.
void FlushPretenuringFeedback();
// Checks if all threads are stopped.
bool IsStopped();
size_t TotalMarkedBytes();
void set_another_ephemeron_iteration(bool another_ephemeron_iteration) {
another_ephemeron_iteration_.store(another_ephemeron_iteration);
}
bool another_ephemeron_iteration() {
return another_ephemeron_iteration_.load();
}
GarbageCollector garbage_collector() const {
DCHECK(garbage_collector_.has_value());
return garbage_collector_.value();
}
bool IsWorkLeft() const;
private:
struct TaskState;
class JobTaskMinor;
class JobTaskMajor;
class MinorMarkingState;
void RunMinor(JobDelegate* delegate);
template <YoungGenerationMarkingVisitationMode marking_mode>
size_t RunMinorImpl(JobDelegate* delegate, TaskState* task_state);
void RunMajor(JobDelegate* delegate,
base::EnumSet<CodeFlushMode> code_flush_mode,
unsigned mark_compact_epoch, bool should_keep_ages_unchanged);
size_t GetMajorMaxConcurrency(size_t worker_count);
size_t GetMinorMaxConcurrency(size_t worker_count);
void Resume();
std::unique_ptr<JobHandle> job_handle_;
Heap* const heap_;
base::Optional<GarbageCollector> garbage_collector_;
MarkingWorklists* marking_worklists_;
WeakObjects* const weak_objects_;
std::vector<std::unique_ptr<TaskState>> task_state_;
std::atomic<size_t> total_marked_bytes_{0};
std::atomic<bool> another_ephemeron_iteration_{false};
base::Optional<uint64_t> current_job_trace_id_;
std::unique_ptr<MinorMarkingState> minor_marking_state_;
friend class Heap;
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_CONCURRENT_MARKING_H_
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