Configure threads with their own warning deadlines.

Design document:
https://docs.google.com/document/d/1c_Jk-eqoBl3mZcEW73OO_WOnWVO9nTU854DHcyqjQBo/edit?resourcekey=0-j2bRwX0nxCldQ_VjoPFAOQ#

Bug: webrtc:12405
Change-Id: Idab950a3293d7ca9328dfeb19ec6d3084f7e0e5f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/203522
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33218}

pc/connection_context.cc

@@ -125,6 +125,14 @@ ConnectionContext::ConnectionContext(
       worker_thread(), network_thread());
 
   channel_manager_->SetVideoRtxEnabled(true);
+  // Set warning levels on the threads, to give warnings when response
+  // may be slower than is expected of the thread.
+  // Since some of the threads may be the same, start with the least
+  // restrictive limits and end with the least permissive ones.
+  // This will give warnings for all cases.
+  signaling_thread_->SetDispatchWarningMs(100);
+  worker_thread_->SetDispatchWarningMs(30);
+  network_thread_->SetDispatchWarningMs(10);
 }
 
 ConnectionContext::~ConnectionContext() {

rtc_base/thread.cc

@@ -71,8 +71,6 @@ class ScopedAutoReleasePool {
 namespace rtc {
 namespace {
 
-const int kSlowDispatchLoggingThreshold = 50;  // 50 ms
-
 class MessageHandlerWithTask final : public MessageHandler {
  public:
   MessageHandlerWithTask() {}
@@ -681,14 +679,18 @@ void Thread::Dispatch(Message* pmsg) {
   TRACE_EVENT2("webrtc", "Thread::Dispatch", "src_file",
                pmsg->posted_from.file_name(), "src_func",
                pmsg->posted_from.function_name());
+  RTC_DCHECK_RUN_ON(this);
   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) {
+  if (diff >= dispatch_warning_ms_) {
-    RTC_LOG(LS_INFO) << "Message took " << diff
+    RTC_LOG(LS_INFO) << "Message to " << name() << " took " << diff
                      << "ms to dispatch. Posted from: "
                      << pmsg->posted_from.ToString();
+    // To avoid log spew, move the warning limit to only give warning
+    // for delays that are larger than the one observed.
+    dispatch_warning_ms_ = diff + 1;
   }
 }
 
@@ -740,6 +742,16 @@ bool Thread::SetName(const std::string& name, const void* obj) {
   return true;
 }
 
+void Thread::SetDispatchWarningMs(int deadline) {
+  if (!IsCurrent()) {
+    PostTask(webrtc::ToQueuedTask(
+        [this, deadline]() { SetDispatchWarningMs(deadline); }));
+    return;
+  }
+  RTC_DCHECK_RUN_ON(this);
+  dispatch_warning_ms_ = deadline;
+}
+
 bool Thread::Start() {
   RTC_DCHECK(!IsRunning());
 

rtc_base/thread.h

@@ -290,6 +290,11 @@ class RTC_LOCKABLE RTC_EXPORT Thread : public webrtc::TaskQueueBase {
   const std::string& name() const { return name_; }
   bool SetName(const std::string& name, const void* obj);
 
+  // Sets the expected processing time in ms. The thread will write
+  // log messages when Invoke() takes more time than this.
+  // Default is 50 ms.
+  void SetDispatchWarningMs(int deadline);
+
   // Starts the execution of the thread.
   bool Start();
 
@@ -525,6 +530,8 @@ class RTC_LOCKABLE RTC_EXPORT Thread : public webrtc::TaskQueueBase {
   RecursiveCriticalSection* CritForTest() { return &crit_; }
 
  private:
+  static const int kSlowDispatchLoggingThreshold = 50;  // 50 ms
+
   class QueuedTaskHandler final : public MessageHandler {
    public:
     QueuedTaskHandler() {}
@@ -614,6 +621,8 @@ class RTC_LOCKABLE RTC_EXPORT Thread : public webrtc::TaskQueueBase {
 
   friend class ThreadManager;
 
+  int dispatch_warning_ms_ RTC_GUARDED_BY(this) = kSlowDispatchLoggingThreshold;
+
   RTC_DISALLOW_COPY_AND_ASSIGN(Thread);
 };