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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/safepoint.h"
#include "src/handles/local-handles.h"
#include "src/handles/persistent-handles.h"
#include "src/heap/heap.h"
#include "src/heap/local-heap.h"
namespace v8 {
namespace internal {
GlobalSafepoint::GlobalSafepoint(Heap* heap)
: heap_(heap), local_heaps_head_(nullptr), is_active_(false) {}
void GlobalSafepoint::Start() { StopThreads(); }
void GlobalSafepoint::End() { ResumeThreads(); }
void GlobalSafepoint::StopThreads() {
local_heaps_mutex_.Lock();
barrier_.Arm();
for (LocalHeap* current = local_heaps_head_; current;
current = current->next_) {
current->RequestSafepoint();
}
for (LocalHeap* current = local_heaps_head_; current;
current = current->next_) {
current->state_mutex_.Lock();
while (current->state_ == LocalHeap::ThreadState::Running) {
current->state_change_.Wait(¤t->state_mutex_);
}
}
is_active_ = true;
}
void GlobalSafepoint::ResumeThreads() {
is_active_ = false;
for (LocalHeap* current = local_heaps_head_; current;
current = current->next_) {
current->state_mutex_.Unlock();
}
barrier_.Disarm();
local_heaps_mutex_.Unlock();
}
void GlobalSafepoint::EnterFromThread(LocalHeap* local_heap) {
{
base::MutexGuard guard(&local_heap->state_mutex_);
local_heap->state_ = LocalHeap::ThreadState::Safepoint;
local_heap->state_change_.NotifyAll();
}
barrier_.Wait();
{
base::MutexGuard guard(&local_heap->state_mutex_);
local_heap->state_ = LocalHeap::ThreadState::Running;
}
}
void GlobalSafepoint::Barrier::Arm() {
base::MutexGuard guard(&mutex_);
CHECK(!armed_);
armed_ = true;
}
void GlobalSafepoint::Barrier::Disarm() {
base::MutexGuard guard(&mutex_);
CHECK(armed_);
armed_ = false;
cond_.NotifyAll();
}
void GlobalSafepoint::Barrier::Wait() {
base::MutexGuard guard(&mutex_);
while (armed_) {
cond_.Wait(&mutex_);
}
}
SafepointScope::SafepointScope(Heap* heap) : safepoint_(heap->safepoint()) {
if (FLAG_local_heaps) safepoint_->StopThreads();
}
SafepointScope::~SafepointScope() {
if (FLAG_local_heaps) safepoint_->ResumeThreads();
}
void GlobalSafepoint::AddLocalHeap(LocalHeap* local_heap) {
base::MutexGuard guard(&local_heaps_mutex_);
if (local_heaps_head_) local_heaps_head_->prev_ = local_heap;
local_heap->prev_ = nullptr;
local_heap->next_ = local_heaps_head_;
local_heaps_head_ = local_heap;
}
void GlobalSafepoint::RemoveLocalHeap(LocalHeap* local_heap) {
base::MutexGuard guard(&local_heaps_mutex_);
if (local_heap->next_) local_heap->next_->prev_ = local_heap->prev_;
if (local_heap->prev_)
local_heap->prev_->next_ = local_heap->next_;
else
local_heaps_head_ = local_heap->next_;
}
bool GlobalSafepoint::ContainsLocalHeap(LocalHeap* local_heap) {
base::MutexGuard guard(&local_heaps_mutex_);
LocalHeap* current = local_heaps_head_;
while (current) {
if (current == local_heap) return true;
current = current->next_;
}
return false;
}
bool GlobalSafepoint::ContainsAnyLocalHeap() {
base::MutexGuard guard(&local_heaps_mutex_);
return local_heaps_head_ != nullptr;
}
void GlobalSafepoint::Iterate(RootVisitor* visitor) {
DCHECK(IsActive());
for (LocalHeap* current = local_heaps_head_; current;
current = current->next_) {
current->handles()->Iterate(visitor);
}
}
} // namespace internal
} // namespace v8
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