blob: 503d5aff966bde3354352173891fe93e91350ce6 [file] [log] [blame]
/*
* Copyright 2004 The WebRTC 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 in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <algorithm>
#include "webrtc/base/atomicops.h"
#include "webrtc/base/checks.h"
#include "webrtc/base/common.h"
#include "webrtc/base/logging.h"
#include "webrtc/base/messagequeue.h"
#include "webrtc/base/stringencode.h"
#include "webrtc/base/thread.h"
#include "webrtc/base/trace_event.h"
namespace rtc {
namespace {
const int kMaxMsgLatency = 150; // 150 ms
const int kSlowDispatchLoggingThreshold = 50; // 50 ms
class SCOPED_LOCKABLE DebugNonReentrantCritScope {
public:
DebugNonReentrantCritScope(const CriticalSection* cs, bool* locked)
EXCLUSIVE_LOCK_FUNCTION(cs)
: cs_(cs), locked_(locked) {
cs_->Enter();
ASSERT(!*locked_);
*locked_ = true;
}
~DebugNonReentrantCritScope() UNLOCK_FUNCTION() {
*locked_ = false;
cs_->Leave();
}
private:
const CriticalSection* const cs_;
bool* locked_;
RTC_DISALLOW_COPY_AND_ASSIGN(DebugNonReentrantCritScope);
};
} // namespace
//------------------------------------------------------------------
// MessageQueueManager
MessageQueueManager* MessageQueueManager::instance_ = NULL;
MessageQueueManager* MessageQueueManager::Instance() {
// Note: This is not thread safe, but it is first called before threads are
// spawned.
if (!instance_)
instance_ = new MessageQueueManager;
return instance_;
}
bool MessageQueueManager::IsInitialized() {
return instance_ != NULL;
}
MessageQueueManager::MessageQueueManager() : locked_(false) {}
MessageQueueManager::~MessageQueueManager() {
}
void MessageQueueManager::Add(MessageQueue *message_queue) {
return Instance()->AddInternal(message_queue);
}
void MessageQueueManager::AddInternal(MessageQueue *message_queue) {
DebugNonReentrantCritScope cs(&crit_, &locked_);
message_queues_.push_back(message_queue);
}
void MessageQueueManager::Remove(MessageQueue *message_queue) {
// If there isn't a message queue manager instance, then there isn't a queue
// to remove.
if (!instance_) return;
return Instance()->RemoveInternal(message_queue);
}
void MessageQueueManager::RemoveInternal(MessageQueue *message_queue) {
// If this is the last MessageQueue, destroy the manager as well so that
// we don't leak this object at program shutdown. As mentioned above, this is
// not thread-safe, but this should only happen at program termination (when
// the ThreadManager is destroyed, and threads are no longer active).
bool destroy = false;
{
DebugNonReentrantCritScope cs(&crit_, &locked_);
std::vector<MessageQueue *>::iterator iter;
iter = std::find(message_queues_.begin(), message_queues_.end(),
message_queue);
if (iter != message_queues_.end()) {
message_queues_.erase(iter);
}
destroy = message_queues_.empty();
}
if (destroy) {
instance_ = NULL;
delete this;
}
}
void MessageQueueManager::Clear(MessageHandler *handler) {
// If there isn't a message queue manager instance, then there aren't any
// queues to remove this handler from.
if (!instance_) return;
return Instance()->ClearInternal(handler);
}
void MessageQueueManager::ClearInternal(MessageHandler *handler) {
DebugNonReentrantCritScope cs(&crit_, &locked_);
std::vector<MessageQueue *>::iterator iter;
for (iter = message_queues_.begin(); iter != message_queues_.end(); iter++)
(*iter)->Clear(handler);
}
void MessageQueueManager::ProcessAllMessageQueues() {
if (!instance_) {
return;
}
return Instance()->ProcessAllMessageQueuesInternal();
}
void MessageQueueManager::ProcessAllMessageQueuesInternal() {
// This works by posting a delayed message at the current time and waiting
// for it to be dispatched on all queues, which will ensure that all messages
// that came before it were also dispatched.
volatile int queues_not_done = 0;
// This class is used so that whether the posted message is processed, or the
// message queue is simply cleared, queues_not_done gets decremented.
class ScopedIncrement : public MessageData {
public:
ScopedIncrement(volatile int* value) : value_(value) {
AtomicOps::Increment(value_);
}
~ScopedIncrement() override { AtomicOps::Decrement(value_); }
private:
volatile int* value_;
};
{
DebugNonReentrantCritScope cs(&crit_, &locked_);
for (MessageQueue* queue : message_queues_) {
if (queue->IsQuitting()) {
// If the queue is quitting, it's done processing messages so it can
// be ignored. If we tried to post a message to it, it would be dropped.
continue;
}
queue->PostDelayed(RTC_FROM_HERE, 0, nullptr, MQID_DISPOSE,
new ScopedIncrement(&queues_not_done));
}
}
// Note: One of the message queues may have been on this thread, which is why
// we can't synchronously wait for queues_not_done to go to 0; we need to
// process messages as well.
while (AtomicOps::AcquireLoad(&queues_not_done) > 0) {
rtc::Thread::Current()->ProcessMessages(0);
}
}
//------------------------------------------------------------------
// MessageQueue
MessageQueue::MessageQueue(SocketServer* ss, bool init_queue)
: fPeekKeep_(false),
dmsgq_next_num_(0),
fInitialized_(false),
fDestroyed_(false),
stop_(0),
ss_(ss) {
RTC_DCHECK(ss);
// Currently, MessageQueue holds a socket server, and is the base class for
// Thread. It seems like it makes more sense for Thread to hold the socket
// server, and provide it to the MessageQueue, since the Thread controls
// the I/O model, and MQ is agnostic to those details. Anyway, this causes
// messagequeue_unittest to depend on network libraries... yuck.
ss_->SetMessageQueue(this);
if (init_queue) {
DoInit();
}
}
MessageQueue::MessageQueue(std::unique_ptr<SocketServer> ss, bool init_queue)
: MessageQueue(ss.get(), init_queue) {
own_ss_ = std::move(ss);
}
MessageQueue::~MessageQueue() {
DoDestroy();
}
void MessageQueue::DoInit() {
if (fInitialized_) {
return;
}
fInitialized_ = true;
MessageQueueManager::Add(this);
}
void MessageQueue::DoDestroy() {
if (fDestroyed_) {
return;
}
fDestroyed_ = true;
// The signal is done from here to ensure
// that it always gets called when the queue
// is going away.
SignalQueueDestroyed();
MessageQueueManager::Remove(this);
Clear(NULL);
SharedScope ss(&ss_lock_);
if (ss_) {
ss_->SetMessageQueue(NULL);
}
}
SocketServer* MessageQueue::socketserver() {
SharedScope ss(&ss_lock_);
return ss_;
}
void MessageQueue::set_socketserver(SocketServer* ss) {
// Need to lock exclusively here to prevent simultaneous modifications from
// other threads. Can't be a shared lock to prevent races with other reading
// threads.
// Other places that only read "ss_" can use a shared lock as simultaneous
// read access is allowed.
ExclusiveScope es(&ss_lock_);
ss_ = ss ? ss : own_ss_.get();
ss_->SetMessageQueue(this);
}
void MessageQueue::WakeUpSocketServer() {
SharedScope ss(&ss_lock_);
ss_->WakeUp();
}
void MessageQueue::Quit() {
AtomicOps::ReleaseStore(&stop_, 1);
WakeUpSocketServer();
}
bool MessageQueue::IsQuitting() {
return AtomicOps::AcquireLoad(&stop_) != 0;
}
void MessageQueue::Restart() {
AtomicOps::ReleaseStore(&stop_, 0);
}
bool MessageQueue::Peek(Message *pmsg, int cmsWait) {
if (fPeekKeep_) {
*pmsg = msgPeek_;
return true;
}
if (!Get(pmsg, cmsWait))
return false;
msgPeek_ = *pmsg;
fPeekKeep_ = true;
return true;
}
bool MessageQueue::Get(Message *pmsg, int cmsWait, bool process_io) {
// Return and clear peek if present
// Always return the peek if it exists so there is Peek/Get symmetry
if (fPeekKeep_) {
*pmsg = msgPeek_;
fPeekKeep_ = false;
return true;
}
// Get w/wait + timer scan / dispatch + socket / event multiplexer dispatch
int64_t cmsTotal = cmsWait;
int64_t cmsElapsed = 0;
int64_t msStart = TimeMillis();
int64_t msCurrent = msStart;
while (true) {
// Check for sent messages
ReceiveSends();
// Check for posted events
int64_t cmsDelayNext = kForever;
bool first_pass = true;
while (true) {
// All queue operations need to be locked, but nothing else in this loop
// (specifically handling disposed message) can happen inside the crit.
// Otherwise, disposed MessageHandlers will cause deadlocks.
{
CritScope cs(&crit_);
// On the first pass, check for delayed messages that have been
// triggered and calculate the next trigger time.
if (first_pass) {
first_pass = false;
while (!dmsgq_.empty()) {
if (msCurrent < dmsgq_.top().msTrigger_) {
cmsDelayNext = TimeDiff(dmsgq_.top().msTrigger_, msCurrent);
break;
}
msgq_.push_back(dmsgq_.top().msg_);
dmsgq_.pop();
}
}
// Pull a message off the message queue, if available.
if (msgq_.empty()) {
break;
} else {
*pmsg = msgq_.front();
msgq_.pop_front();
}
} // crit_ is released here.
// Log a warning for time-sensitive messages that we're late to deliver.
if (pmsg->ts_sensitive) {
int64_t delay = TimeDiff(msCurrent, pmsg->ts_sensitive);
if (delay > 0) {
LOG_F(LS_WARNING) << "id: " << pmsg->message_id << " delay: "
<< (delay + kMaxMsgLatency) << "ms";
}
}
// If this was a dispose message, delete it and skip it.
if (MQID_DISPOSE == pmsg->message_id) {
ASSERT(NULL == pmsg->phandler);
delete pmsg->pdata;
*pmsg = Message();
continue;
}
return true;
}
if (IsQuitting())
break;
// Which is shorter, the delay wait or the asked wait?
int64_t cmsNext;
if (cmsWait == kForever) {
cmsNext = cmsDelayNext;
} else {
cmsNext = std::max<int64_t>(0, cmsTotal - cmsElapsed);
if ((cmsDelayNext != kForever) && (cmsDelayNext < cmsNext))
cmsNext = cmsDelayNext;
}
{
// Wait and multiplex in the meantime
SharedScope ss(&ss_lock_);
if (!ss_->Wait(static_cast<int>(cmsNext), process_io))
return false;
}
// If the specified timeout expired, return
msCurrent = TimeMillis();
cmsElapsed = TimeDiff(msCurrent, msStart);
if (cmsWait != kForever) {
if (cmsElapsed >= cmsWait)
return false;
}
}
return false;
}
void MessageQueue::ReceiveSends() {
}
void MessageQueue::Post(const Location& posted_from,
MessageHandler* phandler,
uint32_t id,
MessageData* pdata,
bool time_sensitive) {
if (IsQuitting())
return;
// Keep thread safe
// Add the message to the end of the queue
// Signal for the multiplexer to return
{
CritScope cs(&crit_);
Message msg;
msg.posted_from = posted_from;
msg.phandler = phandler;
msg.message_id = id;
msg.pdata = pdata;
if (time_sensitive) {
msg.ts_sensitive = TimeMillis() + kMaxMsgLatency;
}
msgq_.push_back(msg);
}
WakeUpSocketServer();
}
void MessageQueue::PostDelayed(const Location& posted_from,
int cmsDelay,
MessageHandler* phandler,
uint32_t id,
MessageData* pdata) {
return DoDelayPost(posted_from, cmsDelay, TimeAfter(cmsDelay), phandler, id,
pdata);
}
void MessageQueue::PostAt(const Location& posted_from,
uint32_t tstamp,
MessageHandler* phandler,
uint32_t id,
MessageData* pdata) {
// This should work even if it is used (unexpectedly).
int64_t delay = static_cast<uint32_t>(TimeMillis()) - tstamp;
return DoDelayPost(posted_from, delay, tstamp, phandler, id, pdata);
}
void MessageQueue::PostAt(const Location& posted_from,
int64_t tstamp,
MessageHandler* phandler,
uint32_t id,
MessageData* pdata) {
return DoDelayPost(posted_from, TimeUntil(tstamp), tstamp, phandler, id,
pdata);
}
void MessageQueue::DoDelayPost(const Location& posted_from,
int64_t cmsDelay,
int64_t tstamp,
MessageHandler* phandler,
uint32_t id,
MessageData* pdata) {
if (IsQuitting()) {
return;
}
// Keep thread safe
// Add to the priority queue. Gets sorted soonest first.
// Signal for the multiplexer to return.
{
CritScope cs(&crit_);
Message msg;
msg.posted_from = posted_from;
msg.phandler = phandler;
msg.message_id = id;
msg.pdata = pdata;
DelayedMessage dmsg(cmsDelay, tstamp, dmsgq_next_num_, msg);
dmsgq_.push(dmsg);
// If this message queue processes 1 message every millisecond for 50 days,
// we will wrap this number. Even then, only messages with identical times
// will be misordered, and then only briefly. This is probably ok.
VERIFY(0 != ++dmsgq_next_num_);
}
WakeUpSocketServer();
}
int MessageQueue::GetDelay() {
CritScope cs(&crit_);
if (!msgq_.empty())
return 0;
if (!dmsgq_.empty()) {
int delay = TimeUntil(dmsgq_.top().msTrigger_);
if (delay < 0)
delay = 0;
return delay;
}
return kForever;
}
void MessageQueue::Clear(MessageHandler* phandler,
uint32_t id,
MessageList* removed) {
CritScope cs(&crit_);
// Remove messages with phandler
if (fPeekKeep_ && msgPeek_.Match(phandler, id)) {
if (removed) {
removed->push_back(msgPeek_);
} else {
delete msgPeek_.pdata;
}
fPeekKeep_ = false;
}
// Remove from ordered message queue
for (MessageList::iterator it = msgq_.begin(); it != msgq_.end();) {
if (it->Match(phandler, id)) {
if (removed) {
removed->push_back(*it);
} else {
delete it->pdata;
}
it = msgq_.erase(it);
} else {
++it;
}
}
// Remove from priority queue. Not directly iterable, so use this approach
PriorityQueue::container_type::iterator new_end = dmsgq_.container().begin();
for (PriorityQueue::container_type::iterator it = new_end;
it != dmsgq_.container().end(); ++it) {
if (it->msg_.Match(phandler, id)) {
if (removed) {
removed->push_back(it->msg_);
} else {
delete it->msg_.pdata;
}
} else {
*new_end++ = *it;
}
}
dmsgq_.container().erase(new_end, dmsgq_.container().end());
dmsgq_.reheap();
}
void MessageQueue::Dispatch(Message *pmsg) {
TRACE_EVENT2("webrtc", "MessageQueue::Dispatch", "src_file_and_line",
pmsg->posted_from.file_and_line(), "src_func",
pmsg->posted_from.function_name());
int64_t start_time = TimeMillis();
pmsg->phandler->OnMessage(pmsg);
int64_t end_time = TimeMillis();
int64_t diff = TimeDiff(end_time, start_time);
if (diff >= kSlowDispatchLoggingThreshold) {
LOG(LS_INFO) << "Message took " << diff << "ms to dispatch. Posted from: "
<< pmsg->posted_from.ToString();
}
}
} // namespace rtc