| // Copyright 2012 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/execution/v8threads.h" |
| |
| #include "include/v8-locker.h" |
| #include "src/api/api.h" |
| #include "src/debug/debug.h" |
| #include "src/execution/execution.h" |
| #include "src/execution/isolate-inl.h" |
| #include "src/execution/stack-guard.h" |
| #include "src/init/bootstrapper.h" |
| #include "src/objects/visitors.h" |
| #include "src/regexp/regexp-stack.h" |
| |
| namespace v8 { |
| |
| namespace { |
| |
| // Track whether this V8 instance has ever called v8::Locker. This allows the |
| // API code to verify that the lock is always held when V8 is being entered. |
| base::AtomicWord g_locker_was_ever_used_ = 0; |
| |
| } // namespace |
| |
| // Once the Locker is initialized, the current thread will be guaranteed to have |
| // the lock for a given isolate. |
| void Locker::Initialize(v8::Isolate* isolate) { |
| DCHECK_NOT_NULL(isolate); |
| has_lock_ = false; |
| top_level_ = true; |
| isolate_ = reinterpret_cast<i::Isolate*>(isolate); |
| |
| // Record that the Locker has been used at least once. |
| base::Relaxed_Store(&g_locker_was_ever_used_, 1); |
| isolate_->set_was_locker_ever_used(); |
| |
| // Get the big lock if necessary. |
| if (!isolate_->thread_manager()->IsLockedByCurrentThread()) { |
| isolate_->thread_manager()->Lock(); |
| has_lock_ = true; |
| |
| // This may be a locker within an unlocker in which case we have to |
| // get the saved state for this thread and restore it. |
| if (isolate_->thread_manager()->RestoreThread()) { |
| top_level_ = false; |
| } |
| } |
| DCHECK(isolate_->thread_manager()->IsLockedByCurrentThread()); |
| } |
| |
| bool Locker::IsLocked(v8::Isolate* isolate) { |
| DCHECK_NOT_NULL(isolate); |
| i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate); |
| return i_isolate->thread_manager()->IsLockedByCurrentThread(); |
| } |
| |
| Locker::~Locker() { |
| DCHECK(isolate_->thread_manager()->IsLockedByCurrentThread()); |
| if (has_lock_) { |
| if (top_level_) { |
| isolate_->thread_manager()->FreeThreadResources(); |
| } else { |
| isolate_->thread_manager()->ArchiveThread(); |
| } |
| isolate_->thread_manager()->Unlock(); |
| } |
| } |
| |
| void Unlocker::Initialize(v8::Isolate* isolate) { |
| DCHECK_NOT_NULL(isolate); |
| isolate_ = reinterpret_cast<i::Isolate*>(isolate); |
| DCHECK(isolate_->thread_manager()->IsLockedByCurrentThread()); |
| isolate_->thread_manager()->ArchiveThread(); |
| isolate_->thread_manager()->Unlock(); |
| } |
| |
| Unlocker::~Unlocker() { |
| DCHECK(!isolate_->thread_manager()->IsLockedByCurrentThread()); |
| isolate_->thread_manager()->Lock(); |
| isolate_->thread_manager()->RestoreThread(); |
| } |
| |
| namespace internal { |
| |
| void ThreadManager::InitThread(const ExecutionAccess& lock) { |
| isolate_->InitializeThreadLocal(); |
| isolate_->stack_guard()->InitThread(lock); |
| isolate_->debug()->InitThread(lock); |
| } |
| |
| bool ThreadManager::RestoreThread() { |
| DCHECK(IsLockedByCurrentThread()); |
| // First check whether the current thread has been 'lazily archived', i.e. |
| // not archived at all. If that is the case we put the state storage we |
| // had prepared back in the free list, since we didn't need it after all. |
| if (lazily_archived_thread_ == ThreadId::Current()) { |
| lazily_archived_thread_ = ThreadId::Invalid(); |
| Isolate::PerIsolateThreadData* per_thread = |
| isolate_->FindPerThreadDataForThisThread(); |
| DCHECK_NOT_NULL(per_thread); |
| DCHECK(per_thread->thread_state() == lazily_archived_thread_state_); |
| lazily_archived_thread_state_->set_id(ThreadId::Invalid()); |
| lazily_archived_thread_state_->LinkInto(ThreadState::FREE_LIST); |
| lazily_archived_thread_state_ = nullptr; |
| per_thread->set_thread_state(nullptr); |
| return true; |
| } |
| |
| // Make sure that the preemption thread cannot modify the thread state while |
| // it is being archived or restored. |
| ExecutionAccess access(isolate_); |
| |
| // If there is another thread that was lazily archived then we have to really |
| // archive it now. |
| if (lazily_archived_thread_.IsValid()) { |
| EagerlyArchiveThread(); |
| } |
| Isolate::PerIsolateThreadData* per_thread = |
| isolate_->FindPerThreadDataForThisThread(); |
| if (per_thread == nullptr || per_thread->thread_state() == nullptr) { |
| // This is a new thread. |
| InitThread(access); |
| return false; |
| } |
| ThreadState* state = per_thread->thread_state(); |
| char* from = state->data(); |
| from = isolate_->handle_scope_implementer()->RestoreThread(from); |
| from = isolate_->RestoreThread(from); |
| from = Relocatable::RestoreState(isolate_, from); |
| // Stack guard should be restored before Debug, etc. since Debug etc. might |
| // depend on a correct stack guard. |
| from = isolate_->stack_guard()->RestoreStackGuard(from); |
| from = isolate_->debug()->RestoreDebug(from); |
| from = isolate_->regexp_stack()->RestoreStack(from); |
| from = isolate_->bootstrapper()->RestoreState(from); |
| per_thread->set_thread_state(nullptr); |
| state->set_id(ThreadId::Invalid()); |
| state->Unlink(); |
| state->LinkInto(ThreadState::FREE_LIST); |
| return true; |
| } |
| |
| void ThreadManager::Lock() { |
| mutex_.Lock(); |
| mutex_owner_.store(ThreadId::Current(), std::memory_order_relaxed); |
| DCHECK(IsLockedByCurrentThread()); |
| } |
| |
| void ThreadManager::Unlock() { |
| mutex_owner_.store(ThreadId::Invalid(), std::memory_order_relaxed); |
| mutex_.Unlock(); |
| } |
| |
| static int ArchiveSpacePerThread() { |
| return HandleScopeImplementer::ArchiveSpacePerThread() + |
| Isolate::ArchiveSpacePerThread() + Debug::ArchiveSpacePerThread() + |
| StackGuard::ArchiveSpacePerThread() + |
| RegExpStack::ArchiveSpacePerThread() + |
| Bootstrapper::ArchiveSpacePerThread() + |
| Relocatable::ArchiveSpacePerThread(); |
| } |
| |
| ThreadState::ThreadState(ThreadManager* thread_manager) |
| : id_(ThreadId::Invalid()), |
| data_(nullptr), |
| next_(this), |
| previous_(this), |
| thread_manager_(thread_manager) {} |
| |
| ThreadState::~ThreadState() { DeleteArray<char>(data_); } |
| |
| void ThreadState::AllocateSpace() { |
| data_ = NewArray<char>(ArchiveSpacePerThread()); |
| } |
| |
| void ThreadState::Unlink() { |
| next_->previous_ = previous_; |
| previous_->next_ = next_; |
| } |
| |
| void ThreadState::LinkInto(List list) { |
| ThreadState* flying_anchor = list == FREE_LIST |
| ? thread_manager_->free_anchor_ |
| : thread_manager_->in_use_anchor_; |
| next_ = flying_anchor->next_; |
| previous_ = flying_anchor; |
| flying_anchor->next_ = this; |
| next_->previous_ = this; |
| } |
| |
| ThreadState* ThreadManager::GetFreeThreadState() { |
| ThreadState* gotten = free_anchor_->next_; |
| if (gotten == free_anchor_) { |
| ThreadState* new_thread_state = new ThreadState(this); |
| new_thread_state->AllocateSpace(); |
| return new_thread_state; |
| } |
| return gotten; |
| } |
| |
| // Gets the first in the list of archived threads. |
| ThreadState* ThreadManager::FirstThreadStateInUse() { |
| return in_use_anchor_->Next(); |
| } |
| |
| ThreadState* ThreadState::Next() { |
| if (next_ == thread_manager_->in_use_anchor_) return nullptr; |
| return next_; |
| } |
| |
| // Thread ids must start with 1, because in TLS having thread id 0 can't |
| // be distinguished from not having a thread id at all (since NULL is |
| // defined as 0.) |
| ThreadManager::ThreadManager(Isolate* isolate) |
| : mutex_owner_(ThreadId::Invalid()), |
| lazily_archived_thread_(ThreadId::Invalid()), |
| lazily_archived_thread_state_(nullptr), |
| free_anchor_(nullptr), |
| in_use_anchor_(nullptr), |
| isolate_(isolate) { |
| free_anchor_ = new ThreadState(this); |
| in_use_anchor_ = new ThreadState(this); |
| } |
| |
| ThreadManager::~ThreadManager() { |
| DeleteThreadStateList(free_anchor_); |
| DeleteThreadStateList(in_use_anchor_); |
| } |
| |
| void ThreadManager::DeleteThreadStateList(ThreadState* anchor) { |
| // The list starts and ends with the anchor. |
| for (ThreadState* current = anchor->next_; current != anchor;) { |
| ThreadState* next = current->next_; |
| delete current; |
| current = next; |
| } |
| delete anchor; |
| } |
| |
| void ThreadManager::ArchiveThread() { |
| DCHECK_EQ(lazily_archived_thread_, ThreadId::Invalid()); |
| DCHECK(!IsArchived()); |
| DCHECK(IsLockedByCurrentThread()); |
| ThreadState* state = GetFreeThreadState(); |
| state->Unlink(); |
| Isolate::PerIsolateThreadData* per_thread = |
| isolate_->FindOrAllocatePerThreadDataForThisThread(); |
| per_thread->set_thread_state(state); |
| lazily_archived_thread_ = ThreadId::Current(); |
| lazily_archived_thread_state_ = state; |
| DCHECK_EQ(state->id(), ThreadId::Invalid()); |
| state->set_id(CurrentId()); |
| DCHECK_NE(state->id(), ThreadId::Invalid()); |
| } |
| |
| void ThreadManager::EagerlyArchiveThread() { |
| DCHECK(IsLockedByCurrentThread()); |
| ThreadState* state = lazily_archived_thread_state_; |
| state->LinkInto(ThreadState::IN_USE_LIST); |
| char* to = state->data(); |
| // Ensure that data containing GC roots are archived first, and handle them |
| // in ThreadManager::Iterate(RootVisitor*). |
| to = isolate_->handle_scope_implementer()->ArchiveThread(to); |
| to = isolate_->ArchiveThread(to); |
| to = Relocatable::ArchiveState(isolate_, to); |
| to = isolate_->stack_guard()->ArchiveStackGuard(to); |
| to = isolate_->debug()->ArchiveDebug(to); |
| to = isolate_->regexp_stack()->ArchiveStack(to); |
| to = isolate_->bootstrapper()->ArchiveState(to); |
| lazily_archived_thread_ = ThreadId::Invalid(); |
| lazily_archived_thread_state_ = nullptr; |
| } |
| |
| void ThreadManager::FreeThreadResources() { |
| DCHECK(!isolate_->has_pending_exception()); |
| DCHECK(!isolate_->external_caught_exception()); |
| DCHECK_NULL(isolate_->try_catch_handler()); |
| isolate_->handle_scope_implementer()->FreeThreadResources(); |
| isolate_->FreeThreadResources(); |
| isolate_->debug()->FreeThreadResources(); |
| isolate_->stack_guard()->FreeThreadResources(); |
| isolate_->regexp_stack()->FreeThreadResources(); |
| isolate_->bootstrapper()->FreeThreadResources(); |
| } |
| |
| bool ThreadManager::IsArchived() { |
| Isolate::PerIsolateThreadData* data = |
| isolate_->FindPerThreadDataForThisThread(); |
| return data != nullptr && data->thread_state() != nullptr; |
| } |
| |
| void ThreadManager::Iterate(RootVisitor* v) { |
| // Expecting no threads during serialization/deserialization |
| for (ThreadState* state = FirstThreadStateInUse(); state != nullptr; |
| state = state->Next()) { |
| char* data = state->data(); |
| data = HandleScopeImplementer::Iterate(v, data); |
| data = isolate_->Iterate(v, data); |
| data = Relocatable::Iterate(v, data); |
| data = StackGuard::Iterate(v, data); |
| data = Debug::Iterate(v, data); |
| } |
| } |
| |
| void ThreadManager::IterateArchivedThreads(ThreadVisitor* v) { |
| for (ThreadState* state = FirstThreadStateInUse(); state != nullptr; |
| state = state->Next()) { |
| char* data = state->data(); |
| data += HandleScopeImplementer::ArchiveSpacePerThread(); |
| isolate_->IterateThread(v, data); |
| } |
| } |
| |
| ThreadId ThreadManager::CurrentId() { return ThreadId::Current(); } |
| |
| } // namespace internal |
| } // namespace v8 |