| // Copyright (c) 2009 The Chromium 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 "base/message_loop.h" |
| |
| #include <algorithm> |
| |
| #include "base/compiler_specific.h" |
| #include "base/lazy_instance.h" |
| #include "base/logging.h" |
| #include "base/message_pump_default.h" |
| #include "base/string_util.h" |
| #include "base/thread_local.h" |
| |
| #if defined(OS_MACOSX) |
| #include "base/message_pump_mac.h" |
| #endif |
| #if defined(OS_POSIX) |
| #include "base/message_pump_libevent.h" |
| #include "base/third_party/valgrind/valgrind.h" |
| #endif |
| #if defined(OS_LINUX) |
| #include "base/message_pump_glib.h" |
| #endif |
| |
| using base::Time; |
| using base::TimeDelta; |
| |
| // A lazily created thread local storage for quick access to a thread's message |
| // loop, if one exists. This should be safe and free of static constructors. |
| static base::LazyInstance<base::ThreadLocalPointer<MessageLoop> > lazy_tls_ptr( |
| base::LINKER_INITIALIZED); |
| |
| //------------------------------------------------------------------------------ |
| |
| // Logical events for Histogram profiling. Run with -message-loop-histogrammer |
| // to get an accounting of messages and actions taken on each thread. |
| static const int kTaskRunEvent = 0x1; |
| static const int kTimerEvent = 0x2; |
| |
| // Provide range of message IDs for use in histogramming and debug display. |
| static const int kLeastNonZeroMessageId = 1; |
| static const int kMaxMessageId = 1099; |
| static const int kNumberOfDistinctMessagesDisplayed = 1100; |
| |
| //------------------------------------------------------------------------------ |
| |
| #if defined(OS_WIN) |
| |
| // Upon a SEH exception in this thread, it restores the original unhandled |
| // exception filter. |
| static int SEHFilter(LPTOP_LEVEL_EXCEPTION_FILTER old_filter) { |
| ::SetUnhandledExceptionFilter(old_filter); |
| return EXCEPTION_CONTINUE_SEARCH; |
| } |
| |
| // Retrieves a pointer to the current unhandled exception filter. There |
| // is no standalone getter method. |
| static LPTOP_LEVEL_EXCEPTION_FILTER GetTopSEHFilter() { |
| LPTOP_LEVEL_EXCEPTION_FILTER top_filter = NULL; |
| top_filter = ::SetUnhandledExceptionFilter(0); |
| ::SetUnhandledExceptionFilter(top_filter); |
| return top_filter; |
| } |
| |
| #endif // defined(OS_WIN) |
| |
| //------------------------------------------------------------------------------ |
| |
| // static |
| MessageLoop* MessageLoop::current() { |
| // TODO(darin): sadly, we cannot enable this yet since people call us even |
| // when they have no intention of using us. |
| //DCHECK(loop) << "Ouch, did you forget to initialize me?"; |
| return lazy_tls_ptr.Pointer()->Get(); |
| } |
| |
| MessageLoop::MessageLoop(Type type) |
| : type_(type), |
| nestable_tasks_allowed_(true), |
| exception_restoration_(false), |
| state_(NULL), |
| next_sequence_num_(0) { |
| DCHECK(!current()) << "should only have one message loop per thread"; |
| lazy_tls_ptr.Pointer()->Set(this); |
| |
| #if defined(OS_WIN) |
| // TODO(rvargas): Get rid of the OS guards. |
| if (type_ == TYPE_DEFAULT) { |
| pump_ = new base::MessagePumpDefault(); |
| } else if (type_ == TYPE_IO) { |
| pump_ = new base::MessagePumpForIO(); |
| } else { |
| DCHECK(type_ == TYPE_UI); |
| pump_ = new base::MessagePumpForUI(); |
| } |
| #elif defined(OS_POSIX) |
| if (type_ == TYPE_UI) { |
| #if defined(OS_MACOSX) |
| pump_ = base::MessagePumpMac::Create(); |
| #elif defined(OS_LINUX) |
| pump_ = new base::MessagePumpForUI(); |
| #endif // OS_LINUX |
| } else if (type_ == TYPE_IO) { |
| pump_ = new base::MessagePumpLibevent(); |
| } else { |
| pump_ = new base::MessagePumpDefault(); |
| } |
| #endif // OS_POSIX |
| } |
| |
| MessageLoop::~MessageLoop() { |
| DCHECK(this == current()); |
| |
| // Let interested parties have one last shot at accessing this. |
| FOR_EACH_OBSERVER(DestructionObserver, destruction_observers_, |
| WillDestroyCurrentMessageLoop()); |
| |
| DCHECK(!state_); |
| |
| // Clean up any unprocessed tasks, but take care: deleting a task could |
| // result in the addition of more tasks (e.g., via DeleteSoon). We set a |
| // limit on the number of times we will allow a deleted task to generate more |
| // tasks. Normally, we should only pass through this loop once or twice. If |
| // we end up hitting the loop limit, then it is probably due to one task that |
| // is being stubborn. Inspect the queues to see who is left. |
| bool did_work; |
| for (int i = 0; i < 100; ++i) { |
| DeletePendingTasks(); |
| ReloadWorkQueue(); |
| // If we end up with empty queues, then break out of the loop. |
| did_work = DeletePendingTasks(); |
| if (!did_work) |
| break; |
| } |
| DCHECK(!did_work); |
| |
| // OK, now make it so that no one can find us. |
| lazy_tls_ptr.Pointer()->Set(NULL); |
| } |
| |
| void MessageLoop::AddDestructionObserver(DestructionObserver *obs) { |
| DCHECK(this == current()); |
| destruction_observers_.AddObserver(obs); |
| } |
| |
| void MessageLoop::RemoveDestructionObserver(DestructionObserver *obs) { |
| DCHECK(this == current()); |
| destruction_observers_.RemoveObserver(obs); |
| } |
| |
| void MessageLoop::Run() { |
| AutoRunState save_state(this); |
| RunHandler(); |
| } |
| |
| void MessageLoop::RunAllPending() { |
| AutoRunState save_state(this); |
| state_->quit_received = true; // Means run until we would otherwise block. |
| RunHandler(); |
| } |
| |
| // Runs the loop in two different SEH modes: |
| // enable_SEH_restoration_ = false : any unhandled exception goes to the last |
| // one that calls SetUnhandledExceptionFilter(). |
| // enable_SEH_restoration_ = true : any unhandled exception goes to the filter |
| // that was existed before the loop was run. |
| void MessageLoop::RunHandler() { |
| #if defined(OS_WIN) |
| if (exception_restoration_) { |
| RunInternalInSEHFrame(); |
| return; |
| } |
| #endif |
| |
| RunInternal(); |
| } |
| //------------------------------------------------------------------------------ |
| #if defined(OS_WIN) |
| __declspec(noinline) void MessageLoop::RunInternalInSEHFrame() { |
| LPTOP_LEVEL_EXCEPTION_FILTER current_filter = GetTopSEHFilter(); |
| __try { |
| RunInternal(); |
| } __except(SEHFilter(current_filter)) { |
| } |
| return; |
| } |
| #endif |
| //------------------------------------------------------------------------------ |
| |
| void MessageLoop::RunInternal() { |
| DCHECK(this == current()); |
| |
| StartHistogrammer(); |
| |
| #if defined(OS_WIN) || defined(OS_LINUX) |
| if (state_->dispatcher && type() == TYPE_UI) { |
| static_cast<base::MessagePumpForUI*>(pump_.get())-> |
| RunWithDispatcher(this, state_->dispatcher); |
| return; |
| } |
| #endif |
| |
| pump_->Run(this); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Wrapper functions for use in above message loop framework. |
| |
| bool MessageLoop::ProcessNextDelayedNonNestableTask() { |
| if (state_->run_depth != 1) |
| return false; |
| |
| if (deferred_non_nestable_work_queue_.empty()) |
| return false; |
| |
| Task* task = deferred_non_nestable_work_queue_.front().task; |
| deferred_non_nestable_work_queue_.pop(); |
| |
| RunTask(task); |
| return true; |
| } |
| |
| //------------------------------------------------------------------------------ |
| |
| void MessageLoop::Quit() { |
| DCHECK(current() == this); |
| if (state_) { |
| state_->quit_received = true; |
| } else { |
| NOTREACHED() << "Must be inside Run to call Quit"; |
| } |
| } |
| |
| void MessageLoop::PostTask( |
| const tracked_objects::Location& from_here, Task* task) { |
| PostTask_Helper(from_here, task, 0, true); |
| } |
| |
| void MessageLoop::PostDelayedTask( |
| const tracked_objects::Location& from_here, Task* task, int64 delay_ms) { |
| PostTask_Helper(from_here, task, delay_ms, true); |
| } |
| |
| void MessageLoop::PostNonNestableTask( |
| const tracked_objects::Location& from_here, Task* task) { |
| PostTask_Helper(from_here, task, 0, false); |
| } |
| |
| void MessageLoop::PostNonNestableDelayedTask( |
| const tracked_objects::Location& from_here, Task* task, int64 delay_ms) { |
| PostTask_Helper(from_here, task, delay_ms, false); |
| } |
| |
| // Possibly called on a background thread! |
| void MessageLoop::PostTask_Helper( |
| const tracked_objects::Location& from_here, Task* task, int64 delay_ms, |
| bool nestable) { |
| task->SetBirthPlace(from_here); |
| |
| PendingTask pending_task(task, nestable); |
| |
| if (delay_ms > 0) { |
| pending_task.delayed_run_time = |
| Time::Now() + TimeDelta::FromMilliseconds(delay_ms); |
| } else { |
| DCHECK(delay_ms == 0) << "delay should not be negative"; |
| } |
| |
| // Warning: Don't try to short-circuit, and handle this thread's tasks more |
| // directly, as it could starve handling of foreign threads. Put every task |
| // into this queue. |
| |
| scoped_refptr<base::MessagePump> pump; |
| { |
| AutoLock locked(incoming_queue_lock_); |
| |
| bool was_empty = incoming_queue_.empty(); |
| incoming_queue_.push(pending_task); |
| if (!was_empty) |
| return; // Someone else should have started the sub-pump. |
| |
| pump = pump_; |
| } |
| // Since the incoming_queue_ may contain a task that destroys this message |
| // loop, we cannot exit incoming_queue_lock_ until we are done with |this|. |
| // We use a stack-based reference to the message pump so that we can call |
| // ScheduleWork outside of incoming_queue_lock_. |
| |
| pump->ScheduleWork(); |
| } |
| |
| void MessageLoop::SetNestableTasksAllowed(bool allowed) { |
| if (nestable_tasks_allowed_ != allowed) { |
| nestable_tasks_allowed_ = allowed; |
| if (!nestable_tasks_allowed_) |
| return; |
| // Start the native pump if we are not already pumping. |
| pump_->ScheduleWork(); |
| } |
| } |
| |
| bool MessageLoop::NestableTasksAllowed() const { |
| return nestable_tasks_allowed_; |
| } |
| |
| bool MessageLoop::IsNested() { |
| return state_->run_depth > 1; |
| } |
| |
| //------------------------------------------------------------------------------ |
| |
| void MessageLoop::RunTask(Task* task) { |
| DCHECK(nestable_tasks_allowed_); |
| // Execute the task and assume the worst: It is probably not reentrant. |
| nestable_tasks_allowed_ = false; |
| |
| HistogramEvent(kTaskRunEvent); |
| task->Run(); |
| delete task; |
| |
| nestable_tasks_allowed_ = true; |
| } |
| |
| bool MessageLoop::DeferOrRunPendingTask(const PendingTask& pending_task) { |
| if (pending_task.nestable || state_->run_depth == 1) { |
| RunTask(pending_task.task); |
| // Show that we ran a task (Note: a new one might arrive as a |
| // consequence!). |
| return true; |
| } |
| |
| // We couldn't run the task now because we're in a nested message loop |
| // and the task isn't nestable. |
| deferred_non_nestable_work_queue_.push(pending_task); |
| return false; |
| } |
| |
| void MessageLoop::AddToDelayedWorkQueue(const PendingTask& pending_task) { |
| // Move to the delayed work queue. Initialize the sequence number |
| // before inserting into the delayed_work_queue_. The sequence number |
| // is used to faciliate FIFO sorting when two tasks have the same |
| // delayed_run_time value. |
| PendingTask new_pending_task(pending_task); |
| new_pending_task.sequence_num = next_sequence_num_++; |
| delayed_work_queue_.push(new_pending_task); |
| } |
| |
| void MessageLoop::ReloadWorkQueue() { |
| // We can improve performance of our loading tasks from incoming_queue_ to |
| // work_queue_ by waiting until the last minute (work_queue_ is empty) to |
| // load. That reduces the number of locks-per-task significantly when our |
| // queues get large. |
| if (!work_queue_.empty()) |
| return; // Wait till we *really* need to lock and load. |
| |
| // Acquire all we can from the inter-thread queue with one lock acquisition. |
| { |
| AutoLock lock(incoming_queue_lock_); |
| if (incoming_queue_.empty()) |
| return; |
| incoming_queue_.Swap(&work_queue_); // Constant time |
| DCHECK(incoming_queue_.empty()); |
| } |
| } |
| |
| bool MessageLoop::DeletePendingTasks() { |
| bool did_work = !work_queue_.empty(); |
| while (!work_queue_.empty()) { |
| PendingTask pending_task = work_queue_.front(); |
| work_queue_.pop(); |
| if (!pending_task.delayed_run_time.is_null()) { |
| // We want to delete delayed tasks in the same order in which they would |
| // normally be deleted in case of any funny dependencies between delayed |
| // tasks. |
| AddToDelayedWorkQueue(pending_task); |
| } else { |
| // TODO(darin): Delete all tasks once it is safe to do so. |
| // Until it is totally safe, just do it when running Purify or |
| // Valgrind. |
| #if defined(PURIFY) |
| delete pending_task.task; |
| #elif defined(OS_POSIX) |
| if (RUNNING_ON_VALGRIND) |
| delete pending_task.task; |
| #endif // defined(OS_POSIX) |
| } |
| } |
| did_work |= !deferred_non_nestable_work_queue_.empty(); |
| while (!deferred_non_nestable_work_queue_.empty()) { |
| // TODO(darin): Delete all tasks once it is safe to do so. |
| // Until it is totaly safe, only delete them under Purify and Valgrind. |
| Task* task = NULL; |
| #if defined(PURIFY) |
| task = deferred_non_nestable_work_queue_.front().task; |
| #elif defined(OS_POSIX) |
| if (RUNNING_ON_VALGRIND) |
| task = deferred_non_nestable_work_queue_.front().task; |
| #endif |
| deferred_non_nestable_work_queue_.pop(); |
| if (task) |
| delete task; |
| } |
| did_work |= !delayed_work_queue_.empty(); |
| while (!delayed_work_queue_.empty()) { |
| Task* task = delayed_work_queue_.top().task; |
| delayed_work_queue_.pop(); |
| delete task; |
| } |
| return did_work; |
| } |
| |
| bool MessageLoop::DoWork() { |
| if (!nestable_tasks_allowed_) { |
| // Task can't be executed right now. |
| return false; |
| } |
| |
| for (;;) { |
| ReloadWorkQueue(); |
| if (work_queue_.empty()) |
| break; |
| |
| // Execute oldest task. |
| do { |
| PendingTask pending_task = work_queue_.front(); |
| work_queue_.pop(); |
| if (!pending_task.delayed_run_time.is_null()) { |
| AddToDelayedWorkQueue(pending_task); |
| // If we changed the topmost task, then it is time to re-schedule. |
| if (delayed_work_queue_.top().task == pending_task.task) |
| pump_->ScheduleDelayedWork(pending_task.delayed_run_time); |
| } else { |
| if (DeferOrRunPendingTask(pending_task)) |
| return true; |
| } |
| } while (!work_queue_.empty()); |
| } |
| |
| // Nothing happened. |
| return false; |
| } |
| |
| bool MessageLoop::DoDelayedWork(Time* next_delayed_work_time) { |
| if (!nestable_tasks_allowed_ || delayed_work_queue_.empty()) { |
| *next_delayed_work_time = Time(); |
| return false; |
| } |
| |
| if (delayed_work_queue_.top().delayed_run_time > Time::Now()) { |
| *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time; |
| return false; |
| } |
| |
| PendingTask pending_task = delayed_work_queue_.top(); |
| delayed_work_queue_.pop(); |
| |
| if (!delayed_work_queue_.empty()) |
| *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time; |
| |
| return DeferOrRunPendingTask(pending_task); |
| } |
| |
| bool MessageLoop::DoIdleWork() { |
| if (ProcessNextDelayedNonNestableTask()) |
| return true; |
| |
| if (state_->quit_received) |
| pump_->Quit(); |
| |
| return false; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // MessageLoop::AutoRunState |
| |
| MessageLoop::AutoRunState::AutoRunState(MessageLoop* loop) : loop_(loop) { |
| // Make the loop reference us. |
| previous_state_ = loop_->state_; |
| if (previous_state_) { |
| run_depth = previous_state_->run_depth + 1; |
| } else { |
| run_depth = 1; |
| } |
| loop_->state_ = this; |
| |
| // Initialize the other fields: |
| quit_received = false; |
| #if defined(OS_WIN) || defined(OS_LINUX) |
| dispatcher = NULL; |
| #endif |
| } |
| |
| MessageLoop::AutoRunState::~AutoRunState() { |
| loop_->state_ = previous_state_; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // MessageLoop::PendingTask |
| |
| bool MessageLoop::PendingTask::operator<(const PendingTask& other) const { |
| // Since the top of a priority queue is defined as the "greatest" element, we |
| // need to invert the comparison here. We want the smaller time to be at the |
| // top of the heap. |
| |
| if (delayed_run_time < other.delayed_run_time) |
| return false; |
| |
| if (delayed_run_time > other.delayed_run_time) |
| return true; |
| |
| // If the times happen to match, then we use the sequence number to decide. |
| // Compare the difference to support integer roll-over. |
| return (sequence_num - other.sequence_num) > 0; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Method and data for histogramming events and actions taken by each instance |
| // on each thread. |
| |
| // static |
| bool MessageLoop::enable_histogrammer_ = false; |
| |
| // static |
| void MessageLoop::EnableHistogrammer(bool enable) { |
| enable_histogrammer_ = enable; |
| } |
| |
| void MessageLoop::StartHistogrammer() { |
| if (enable_histogrammer_ && !message_histogram_.get() |
| && StatisticsRecorder::WasStarted()) { |
| DCHECK(!thread_name_.empty()); |
| message_histogram_.reset( |
| new LinearHistogram(("MsgLoop:" + thread_name_).c_str(), |
| kLeastNonZeroMessageId, |
| kMaxMessageId, |
| kNumberOfDistinctMessagesDisplayed)); |
| message_histogram_->SetFlags(message_histogram_->kHexRangePrintingFlag); |
| message_histogram_->SetRangeDescriptions(event_descriptions_); |
| } |
| } |
| |
| void MessageLoop::HistogramEvent(int event) { |
| if (message_histogram_.get()) |
| message_histogram_->Add(event); |
| } |
| |
| // Provide a macro that takes an expression (such as a constant, or macro |
| // constant) and creates a pair to initalize an array of pairs. In this case, |
| // our pair consists of the expressions value, and the "stringized" version |
| // of the expression (i.e., the exrpression put in quotes). For example, if |
| // we have: |
| // #define FOO 2 |
| // #define BAR 5 |
| // then the following: |
| // VALUE_TO_NUMBER_AND_NAME(FOO + BAR) |
| // will expand to: |
| // {7, "FOO + BAR"} |
| // We use the resulting array as an argument to our histogram, which reads the |
| // number as a bucket identifier, and proceeds to use the corresponding name |
| // in the pair (i.e., the quoted string) when printing out a histogram. |
| #define VALUE_TO_NUMBER_AND_NAME(name) {name, #name}, |
| |
| // static |
| const LinearHistogram::DescriptionPair MessageLoop::event_descriptions_[] = { |
| // Provide some pretty print capability in our histogram for our internal |
| // messages. |
| |
| // A few events we handle (kindred to messages), and used to profile actions. |
| VALUE_TO_NUMBER_AND_NAME(kTaskRunEvent) |
| VALUE_TO_NUMBER_AND_NAME(kTimerEvent) |
| |
| {-1, NULL} // The list must be null terminated, per API to histogram. |
| }; |
| |
| //------------------------------------------------------------------------------ |
| // MessageLoopForUI |
| |
| #if defined(OS_WIN) |
| void MessageLoopForUI::WillProcessMessage(const MSG& message) { |
| pump_win()->WillProcessMessage(message); |
| } |
| void MessageLoopForUI::DidProcessMessage(const MSG& message) { |
| pump_win()->DidProcessMessage(message); |
| } |
| void MessageLoopForUI::PumpOutPendingPaintMessages() { |
| pump_ui()->PumpOutPendingPaintMessages(); |
| } |
| |
| #endif // defined(OS_WIN) |
| |
| #if defined(OS_LINUX) || defined(OS_WIN) |
| void MessageLoopForUI::AddObserver(Observer* observer) { |
| pump_ui()->AddObserver(observer); |
| } |
| |
| void MessageLoopForUI::RemoveObserver(Observer* observer) { |
| pump_ui()->RemoveObserver(observer); |
| } |
| |
| void MessageLoopForUI::Run(Dispatcher* dispatcher) { |
| AutoRunState save_state(this); |
| state_->dispatcher = dispatcher; |
| RunHandler(); |
| } |
| #endif // defined(OS_LINUX) || defined(OS_WIN) |
| |
| //------------------------------------------------------------------------------ |
| // MessageLoopForIO |
| |
| #if defined(OS_WIN) |
| |
| void MessageLoopForIO::RegisterIOHandler(HANDLE file, IOHandler* handler) { |
| pump_io()->RegisterIOHandler(file, handler); |
| } |
| |
| bool MessageLoopForIO::WaitForIOCompletion(DWORD timeout, IOHandler* filter) { |
| return pump_io()->WaitForIOCompletion(timeout, filter); |
| } |
| |
| #elif defined(OS_POSIX) |
| |
| bool MessageLoopForIO::WatchFileDescriptor(int fd, |
| bool persistent, |
| Mode mode, |
| FileDescriptorWatcher *controller, |
| Watcher *delegate) { |
| return pump_libevent()->WatchFileDescriptor( |
| fd, |
| persistent, |
| static_cast<base::MessagePumpLibevent::Mode>(mode), |
| controller, |
| delegate); |
| } |
| |
| #endif |