diff -r 000000000000 -r 6474c204b198 content/media/Latency.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/Latency.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,228 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// We want this available in opt builds
+#define FORCE_PR_LOG
+
+#include "Latency.h"
+#include "nsThreadUtils.h"
+#include "prlog.h"
+#include <cmath>
+#include <algorithm>
+
+#include <mozilla/Services.h>
+#include <mozilla/StaticPtr.h>
+#include "nsContentUtils.h"
+
+using namespace mozilla;
+
+const char* LatencyLogIndex2Strings[] = {
+  "Audio MediaStreamTrack",
+  "Video MediaStreamTrack",
+  "Cubeb",
+  "AudioStream",
+  "NetEQ",
+  "AudioCapture Base",
+  "AudioCapture Samples",
+  "AudioTrackInsertion",
+  "MediaPipeline Audio Insertion",
+  "AudioTransmit",
+  "AudioReceive",
+  "MediaPipelineAudioPlayout",
+  "MediaStream Create",
+  "AudioStream Create",
+  "AudioSendRTP",
+  "AudioRecvRTP"
+};
+
+static StaticRefPtr<AsyncLatencyLogger> gAsyncLogger;
+
+PRLogModuleInfo*
+GetLatencyLog()
+{
+  static PRLogModuleInfo* sLog;
+  if (!sLog) {
+    sLog = PR_NewLogModule("MediaLatency");
+  }
+  return sLog;
+}
+
+
+class LogEvent : public nsRunnable
+{
+public:
+  LogEvent(AsyncLatencyLogger::LatencyLogIndex aIndex, uint64_t aID, int64_t aValue,
+           TimeStamp aTimeStamp) :
+    mIndex(aIndex),
+    mID(aID),
+    mValue(aValue),
+    mTimeStamp(aTimeStamp)
+  {}
+  LogEvent(AsyncLatencyLogger::LatencyLogIndex aIndex, uint64_t aID, int64_t aValue) :
+    mIndex(aIndex),
+    mID(aID),
+    mValue(aValue),
+    mTimeStamp(TimeStamp())
+  {}
+  ~LogEvent() {}
+
+  NS_IMETHOD Run() {
+    AsyncLatencyLogger::Get(true)->WriteLog(mIndex, mID, mValue, mTimeStamp);
+    return NS_OK;
+  }
+
+protected:
+  AsyncLatencyLogger::LatencyLogIndex mIndex;
+  uint64_t mID;
+  int64_t mValue;
+  TimeStamp mTimeStamp;
+};
+
+void LogLatency(AsyncLatencyLogger::LatencyLogIndex aIndex, uint64_t aID, int64_t aValue)
+{
+  AsyncLatencyLogger::Get()->Log(aIndex, aID, aValue);
+}
+
+void LogTime(AsyncLatencyLogger::LatencyLogIndex aIndex, uint64_t aID, int64_t aValue)
+{
+  TimeStamp now = TimeStamp::Now();
+  AsyncLatencyLogger::Get()->Log(aIndex, aID, aValue, now);
+}
+
+void LogTime(AsyncLatencyLogger::LatencyLogIndex aIndex, uint64_t aID, int64_t aValue, TimeStamp &aTime)
+{
+  AsyncLatencyLogger::Get()->Log(aIndex, aID, aValue, aTime);
+}
+
+void LogTime(uint32_t aIndex, uint64_t aID, int64_t aValue)
+{
+  LogTime(static_cast<AsyncLatencyLogger::LatencyLogIndex>(aIndex), aID, aValue);
+}
+void LogTime(uint32_t aIndex, uint64_t aID, int64_t aValue, TimeStamp &aTime)
+{
+  LogTime(static_cast<AsyncLatencyLogger::LatencyLogIndex>(aIndex), aID, aValue, aTime);
+}
+void LogLatency(uint32_t aIndex, uint64_t aID, int64_t aValue)
+{
+  LogLatency(static_cast<AsyncLatencyLogger::LatencyLogIndex>(aIndex), aID, aValue);
+}
+
+/* static */
+void AsyncLatencyLogger::InitializeStatics()
+{
+  NS_ASSERTION(NS_IsMainThread(), "Main thread only");
+  GetLatencyLog();
+  gAsyncLogger = new AsyncLatencyLogger();
+}
+
+/* static */
+void AsyncLatencyLogger::ShutdownLogger()
+{
+  gAsyncLogger = nullptr;
+}
+
+/* static */
+AsyncLatencyLogger* AsyncLatencyLogger::Get(bool aStartTimer)
+{
+  // Users don't generally null-check the result since we should live longer than they
+  MOZ_ASSERT(gAsyncLogger);
+
+  if (aStartTimer) {
+    gAsyncLogger->Init();
+  }
+  return gAsyncLogger;
+}
+
+NS_IMPL_ISUPPORTS(AsyncLatencyLogger, nsIObserver)
+
+AsyncLatencyLogger::AsyncLatencyLogger()
+  : mThread(nullptr),
+    mMutex("AsyncLatencyLogger")
+{
+  NS_ASSERTION(NS_IsMainThread(), "Main thread only");
+  nsContentUtils::RegisterShutdownObserver(this);
+}
+
+AsyncLatencyLogger::~AsyncLatencyLogger()
+{
+  AsyncLatencyLogger::Shutdown();
+}
+
+void AsyncLatencyLogger::Shutdown()
+{
+  nsContentUtils::UnregisterShutdownObserver(this);
+
+  MutexAutoLock lock(mMutex);
+  if (mThread) {
+    mThread->Shutdown();
+  }
+  mStart = TimeStamp(); // make sure we don't try to restart it for any reason
+}
+
+void AsyncLatencyLogger::Init()
+{
+  MutexAutoLock lock(mMutex);
+  if (mStart.IsNull()) {
+    nsresult rv = NS_NewNamedThread("Latency Logger", getter_AddRefs(mThread));
+    NS_ENSURE_SUCCESS_VOID(rv);
+    mStart = TimeStamp::Now();
+  }
+}
+
+void AsyncLatencyLogger::GetStartTime(TimeStamp &aStart)
+{
+  MutexAutoLock lock(mMutex);
+  aStart = mStart;
+}
+
+nsresult
+AsyncLatencyLogger::Observe(nsISupports* aSubject, const char* aTopic,
+                            const char16_t* aData)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
+    Shutdown();
+  }
+  return NS_OK;
+}
+
+// aID is a sub-identifier (in particular a specific MediaStramTrack)
+void AsyncLatencyLogger::WriteLog(LatencyLogIndex aIndex, uint64_t aID, int64_t aValue,
+                                  TimeStamp aTimeStamp)
+{
+  if (aTimeStamp.IsNull()) {
+    PR_LOG(GetLatencyLog(), PR_LOG_DEBUG,
+      ("Latency: %s,%llu,%lld,%lld",
+       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue));
+  } else {
+    PR_LOG(GetLatencyLog(), PR_LOG_DEBUG,
+      ("Latency: %s,%llu,%lld,%lld,%lld",
+       LatencyLogIndex2Strings[aIndex], aID, GetTimeStamp(), aValue,
+       static_cast<int64_t>((aTimeStamp - gAsyncLogger->mStart).ToMilliseconds())));
+  }
+}
+
+int64_t AsyncLatencyLogger::GetTimeStamp()
+{
+  TimeDuration t = TimeStamp::Now() - mStart;
+  return t.ToMilliseconds();
+}
+
+void AsyncLatencyLogger::Log(LatencyLogIndex aIndex, uint64_t aID, int64_t aValue)
+{
+  TimeStamp null;
+  Log(aIndex, aID, aValue, null);
+}
+
+void AsyncLatencyLogger::Log(LatencyLogIndex aIndex, uint64_t aID, int64_t aValue, TimeStamp &aTime)
+{
+  if (PR_LOG_TEST(GetLatencyLog(), PR_LOG_DEBUG)) {
+    nsCOMPtr<nsIRunnable> event = new LogEvent(aIndex, aID, aValue, aTime);
+    if (mThread) {
+      mThread->Dispatch(event, NS_DISPATCH_NORMAL);
+    }
+  }
+}