dom/media/CallbackThreadRegistry.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "CallbackThreadRegistry.h"
   8 #include "mozilla/ClearOnShutdown.h"
   9 #include "nsThreadUtils.h"
  10
  11 namespace mozilla {
  12 struct CallbackThreadRegistrySingleton {
  13   CallbackThreadRegistrySingleton()
  14       : mRegistry(MakeUnique<CallbackThreadRegistry>()) {
  15     NS_DispatchToMainThread(
  16         NS_NewRunnableFunction(__func__, [registry = &mRegistry] {
  17           const auto phase = ShutdownPhase::XPCOMShutdownFinal;
  18           MOZ_DIAGNOSTIC_ASSERT(!PastShutdownPhase(phase));
  19           ClearOnShutdown(registry, phase);
  20         }));
  21   }
  22
  23   UniquePtr<CallbackThreadRegistry> mRegistry;
  24 };
  25
  26 CallbackThreadRegistry::CallbackThreadRegistry()
  27     : mThreadIds("CallbackThreadRegistry::mThreadIds") {}
  28
  29 /* static */
  30 CallbackThreadRegistry* CallbackThreadRegistry::Get() {
  31   static CallbackThreadRegistrySingleton sSingleton;
  32   return sSingleton.mRegistry.get();
  33 }
  34
  35 static bool CanLeak() {
  36 #ifdef NS_BUILD_REFCNT_LOGGING
  37   static const bool logging =
  38       getenv("XPCOM_MEM_LEAK_LOG") || getenv("XPCOM_MEM_BLOAT_LOG") ||
  39       getenv("XPCOM_MEM_REFCNT_LOG") || getenv("XPCOM_MEM_ALLOC_LOG") ||
  40       getenv("XPCOM_MEM_COMPTR_LOG");
  41   return logging;
  42 #else
  43   return false;
  44 #endif
  45 }
  46
  47 void CallbackThreadRegistry::Register(ProfilerThreadId aThreadId,
  48                                       const char* aName) {
  49   if (!aThreadId.IsSpecified()) {
  50     // profiler_current_thread_id is unspecified on unsupported platforms.
  51     return;
  52   }
  53
  54   if (CanLeak()) {
  55     NS_WARNING(
  56         "Not registering callback thread due to refcount logging; it may show "
  57         "up as a leak of the TLS-backed nsThread wrapper if the thread "
  58         "outlives xpcom shutdown.");
  59     return;
  60   }
  61
  62   auto threadIds = mThreadIds.Lock();
  63   for (uint32_t i = 0; i < threadIds->Length(); i++) {
  64     if ((*threadIds)[i].mId == aThreadId) {
  65       (*threadIds)[i].mUserCount++;
  66       return;
  67     }
  68   }
  69   ThreadUserCount tuc;
  70   tuc.mId = aThreadId;
  71   tuc.mUserCount = 1;
  72   threadIds->AppendElement(tuc);
  73   PROFILER_REGISTER_THREAD(aName);
  74 }
  75
  76 void CallbackThreadRegistry::Unregister(ProfilerThreadId aThreadId) {
  77   if (!aThreadId.IsSpecified()) {
  78     // profiler_current_thread_id is unspedified on unsupported platforms.
  79     return;
  80   }
  81
  82   if (CanLeak()) {
  83     return;
  84   }
  85
  86   auto threadIds = mThreadIds.Lock();
  87   for (uint32_t i = 0; i < threadIds->Length(); i++) {
  88     if ((*threadIds)[i].mId == aThreadId) {
  89       MOZ_ASSERT((*threadIds)[i].mUserCount > 0);
  90       (*threadIds)[i].mUserCount--;
  91
  92       if ((*threadIds)[i].mUserCount == 0) {
  93         PROFILER_UNREGISTER_THREAD();
  94         threadIds->RemoveElementAt(i);
  95       }
  96       return;
  97     }
  98   }
  99   MOZ_ASSERT_UNREACHABLE("Current thread was not registered");
 100 }
 101
 102 }  // namespace mozilla