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// Copyright 2020 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.
#include "src/heap/cppgc/gc-invoker.h"
#include <memory>
#include "include/cppgc/platform.h"
#include "src/heap/cppgc/heap.h"
#include "src/heap/cppgc/task-handle.h"
namespace cppgc {
namespace internal {
class GCInvoker::GCInvokerImpl final : public GarbageCollector {
public:
GCInvokerImpl(GarbageCollector*, cppgc::Platform*, cppgc::Heap::StackSupport);
~GCInvokerImpl();
GCInvokerImpl(const GCInvokerImpl&) = delete;
GCInvokerImpl& operator=(const GCInvokerImpl&) = delete;
void CollectGarbage(GarbageCollector::Config) final;
void StartIncrementalGarbageCollection(GarbageCollector::Config) final;
size_t epoch() const final { return collector_->epoch(); }
private:
class GCTask final : public cppgc::Task {
public:
using Handle = SingleThreadedHandle;
static Handle Post(GarbageCollector* collector, cppgc::TaskRunner* runner,
GarbageCollector::Config config) {
auto task =
std::make_unique<GCInvoker::GCInvokerImpl::GCTask>(collector, config);
auto handle = task->GetHandle();
runner->PostNonNestableTask(std::move(task));
return handle;
}
explicit GCTask(GarbageCollector* collector,
GarbageCollector::Config config)
: collector_(collector),
config_(config),
handle_(Handle::NonEmptyTag{}),
saved_epoch_(collector->epoch()) {}
private:
void Run() final {
if (handle_.IsCanceled() || (collector_->epoch() != saved_epoch_)) return;
collector_->CollectGarbage(config_);
handle_.Cancel();
}
Handle GetHandle() { return handle_; }
GarbageCollector* collector_;
GarbageCollector::Config config_;
Handle handle_;
size_t saved_epoch_;
};
GarbageCollector* collector_;
cppgc::Platform* platform_;
cppgc::Heap::StackSupport stack_support_;
GCTask::Handle gc_task_handle_;
};
GCInvoker::GCInvokerImpl::GCInvokerImpl(GarbageCollector* collector,
cppgc::Platform* platform,
cppgc::Heap::StackSupport stack_support)
: collector_(collector),
platform_(platform),
stack_support_(stack_support) {}
GCInvoker::GCInvokerImpl::~GCInvokerImpl() {
if (gc_task_handle_) {
gc_task_handle_.Cancel();
}
}
void GCInvoker::GCInvokerImpl::CollectGarbage(GarbageCollector::Config config) {
DCHECK_EQ(config.marking_type, cppgc::Heap::MarkingType::kAtomic);
if ((config.stack_state ==
GarbageCollector::Config::StackState::kNoHeapPointers) ||
(stack_support_ ==
cppgc::Heap::StackSupport::kSupportsConservativeStackScan)) {
collector_->CollectGarbage(config);
} else if (platform_->GetForegroundTaskRunner() &&
platform_->GetForegroundTaskRunner()->NonNestableTasksEnabled()) {
if (!gc_task_handle_) {
// Force a precise GC since it will run in a non-nestable task.
config.stack_state =
GarbageCollector::Config::StackState::kNoHeapPointers;
gc_task_handle_ = GCTask::Post(
collector_, platform_->GetForegroundTaskRunner().get(), config);
}
}
}
void GCInvoker::GCInvokerImpl::StartIncrementalGarbageCollection(
GarbageCollector::Config config) {
DCHECK_NE(config.marking_type, cppgc::Heap::MarkingType::kAtomic);
if ((stack_support_ !=
cppgc::Heap::StackSupport::kSupportsConservativeStackScan) &&
(!platform_->GetForegroundTaskRunner() ||
!platform_->GetForegroundTaskRunner()->NonNestableTasksEnabled())) {
// In this configuration the GC finalization can only be triggered through
// ForceGarbageCollectionSlow. If incremental GC is started, there is no
// way to know how long it will remain enabled (and the write barrier with
// it). For that reason, we do not support running incremental GCs in this
// configuration.
return;
}
// No need to postpone starting incremental GC since the stack is not scanned
// until GC finalization.
collector_->StartIncrementalGarbageCollection(config);
}
GCInvoker::GCInvoker(GarbageCollector* collector, cppgc::Platform* platform,
cppgc::Heap::StackSupport stack_support)
: impl_(std::make_unique<GCInvoker::GCInvokerImpl>(collector, platform,
stack_support)) {}
GCInvoker::~GCInvoker() = default;
void GCInvoker::CollectGarbage(GarbageCollector::Config config) {
impl_->CollectGarbage(config);
}
void GCInvoker::StartIncrementalGarbageCollection(
GarbageCollector::Config config) {
impl_->StartIncrementalGarbageCollection(config);
}
size_t GCInvoker::epoch() const { return impl_->epoch(); }
} // namespace internal
} // namespace cppgc
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