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// Copyright 2016 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_EMBEDDER_TRACING_H_
#define V8_HEAP_EMBEDDER_TRACING_H_
#include "include/v8.h"
#include "src/common/globals.h"
#include "src/flags/flags.h"
namespace v8 {
namespace internal {
class Heap;
class JSObject;
class V8_EXPORT_PRIVATE LocalEmbedderHeapTracer final {
public:
using WrapperInfo = std::pair<void*, void*>;
using WrapperCache = std::vector<WrapperInfo>;
class V8_EXPORT_PRIVATE ProcessingScope {
public:
explicit ProcessingScope(LocalEmbedderHeapTracer* tracer);
~ProcessingScope();
void TracePossibleWrapper(JSObject js_object);
void AddWrapperInfoForTesting(WrapperInfo info);
private:
static constexpr size_t kWrapperCacheSize = 1000;
void FlushWrapperCacheIfFull();
LocalEmbedderHeapTracer* const tracer_;
WrapperCache wrapper_cache_;
};
explicit LocalEmbedderHeapTracer(Isolate* isolate) : isolate_(isolate) {}
~LocalEmbedderHeapTracer() {
if (remote_tracer_) remote_tracer_->isolate_ = nullptr;
}
bool InUse() const { return remote_tracer_ != nullptr; }
EmbedderHeapTracer* remote_tracer() const { return remote_tracer_; }
void SetRemoteTracer(EmbedderHeapTracer* tracer);
void TracePrologue(EmbedderHeapTracer::TraceFlags flags);
void TraceEpilogue();
void EnterFinalPause();
bool Trace(double deadline);
bool IsRemoteTracingDone();
bool IsRootForNonTracingGC(const v8::TracedGlobal<v8::Value>& handle) {
return !InUse() || remote_tracer_->IsRootForNonTracingGC(handle);
}
void NotifyV8MarkingWorklistWasEmpty() {
num_v8_marking_worklist_was_empty_++;
}
bool ShouldFinalizeIncrementalMarking() {
static const size_t kMaxIncrementalFixpointRounds = 3;
return !FLAG_incremental_marking_wrappers || !InUse() ||
(IsRemoteTracingDone() && embedder_worklist_empty_) ||
num_v8_marking_worklist_was_empty_ > kMaxIncrementalFixpointRounds;
}
void SetEmbedderStackStateForNextFinalization(
EmbedderHeapTracer::EmbedderStackState stack_state);
void SetEmbedderWorklistEmpty(bool is_empty) {
embedder_worklist_empty_ = is_empty;
}
void IncreaseAllocatedSize(size_t bytes) {
remote_stats_.allocated_size += bytes;
remote_stats_.accumulated_allocated_size += bytes;
if (remote_stats_.allocated_size >
remote_stats_.allocated_size_limit_for_check) {
StartIncrementalMarkingIfNeeded();
remote_stats_.allocated_size_limit_for_check =
remote_stats_.allocated_size + kEmbedderAllocatedThreshold;
}
}
void StartIncrementalMarkingIfNeeded();
size_t allocated_size() const { return remote_stats_.allocated_size; }
size_t accumulated_allocated_size() const {
return remote_stats_.accumulated_allocated_size;
}
private:
static constexpr size_t kEmbedderAllocatedThreshold = 128 * KB;
Isolate* const isolate_;
EmbedderHeapTracer* remote_tracer_ = nullptr;
size_t num_v8_marking_worklist_was_empty_ = 0;
EmbedderHeapTracer::EmbedderStackState embedder_stack_state_ =
EmbedderHeapTracer::kUnknown;
// Indicates whether the embedder worklist was observed empty on the main
// thread. This is opportunistic as concurrent marking tasks may hold local
// segments of potential embedder fields to move to the main thread.
bool embedder_worklist_empty_ = false;
struct RemoteStatistics {
// Allocated size of objects in bytes reported by the embedder. Updated via
// TraceSummary at the end of tracing and incrementally when the GC is not
// in progress.
size_t allocated_size = 0;
// Limit for |allocated_size_| in bytes to avoid checking for starting a GC
// on each increment.
size_t allocated_size_limit_for_check = 0;
// Totally accumulated bytes allocated by the embedder. Monotonically
// increasing value. Used to approximate allocation rate.
size_t accumulated_allocated_size = 0;
} remote_stats_;
friend class EmbedderStackStateScope;
};
class V8_EXPORT_PRIVATE EmbedderStackStateScope final {
public:
EmbedderStackStateScope(LocalEmbedderHeapTracer* local_tracer,
EmbedderHeapTracer::EmbedderStackState stack_state)
: local_tracer_(local_tracer),
old_stack_state_(local_tracer_->embedder_stack_state_) {
local_tracer_->embedder_stack_state_ = stack_state;
}
~EmbedderStackStateScope() {
local_tracer_->embedder_stack_state_ = old_stack_state_;
}
private:
LocalEmbedderHeapTracer* const local_tracer_;
const EmbedderHeapTracer::EmbedderStackState old_stack_state_;
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_EMBEDDER_TRACING_H_