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
  10 namespace mozilla {
  11 struct CallbackThreadRegistrySingleton {
  12   CallbackThreadRegistrySingleton()
  13       : mRegistry(MakeUnique<CallbackThreadRegistry>()) {
  14     NS_DispatchToMainThread(
  15         NS_NewRunnableFunction(__func__, [registry = &mRegistry] {
  16           const auto phase = ShutdownPhase::XPCOMShutdownFinal;
  17           MOZ_DIAGNOSTIC_ASSERT(!PastShutdownPhase(phase));
  18           ClearOnShutdown(registry, phase);
  19         }));
  20   }
  21
  22   UniquePtr<CallbackThreadRegistry> mRegistry;
  23 };
  24
  25 CallbackThreadRegistry::CallbackThreadRegistry()
  26     : mThreadIds("CallbackThreadRegistry::mThreadIds") {}
  27
  28 /* static */
  29 CallbackThreadRegistry* CallbackThreadRegistry::Get() {
  30   static CallbackThreadRegistrySingleton sSingleton;
  31   return sSingleton.mRegistry.get();
  32 }
  33
  34 static bool CanLeak() {
  35 #ifdef NS_BUILD_REFCNT_LOGGING
  36   static const bool logging =
  37       getenv("XPCOM_MEM_LEAK_LOG") || getenv("XPCOM_MEM_BLOAT_LOG") ||
  38       getenv("XPCOM_MEM_REFCNT_LOG") || getenv("XPCOM_MEM_ALLOC_LOG") ||
  39       getenv("XPCOM_MEM_COMPTR_LOG");
  40   return logging;
  41 #else
  42   return false;
  43 #endif
  44 }
  45
  46 void CallbackThreadRegistry::Register(ProfilerThreadId aThreadId,
  47                                       const char* aName) {
  48   if (!aThreadId.IsSpecified()) {
  49     // profiler_current_thread_id is unspecified on unsupported platforms.
  50     return;
  51   }
  52
  53   if (CanLeak()) {
  54     NS_WARNING(
  55         "Not registering callback thread due to refcount logging; it may show "
  56         "up as a leak of the TLS-backed nsThread wrapper if the thread "
  57         "outlives xpcom shutdown.");
  58     return;
  59   }
  60
  61   auto threadIds = mThreadIds.Lock();
  62   for (uint32_t i = 0; i < threadIds->Length(); i++) {
  63     if ((*threadIds)[i].mId == aThreadId) {
  64       (*threadIds)[i].mUserCount++;
  65       return;
  66     }
  67   }
  68   ThreadUserCount tuc;
  69   tuc.mId = aThreadId;
  70   tuc.mUserCount = 1;
  71   threadIds->AppendElement(tuc);
  72   PROFILER_REGISTER_THREAD(aName);
  73 }
  74
  75 void CallbackThreadRegistry::Unregister(ProfilerThreadId aThreadId) {
  76   if (!aThreadId.IsSpecified()) {
  77     // profiler_current_thread_id is unspedified on unsupported platforms.
  78     return;
  79   }
  80
  81   if (CanLeak()) {
  82     return;
  83   }
  84
  85   auto threadIds = mThreadIds.Lock();
  86   for (uint32_t i = 0; i < threadIds->Length(); i++) {
  87     if ((*threadIds)[i].mId == aThreadId) {
  88       MOZ_ASSERT((*threadIds)[i].mUserCount > 0);
  89       (*threadIds)[i].mUserCount--;
  90
  91       if ((*threadIds)[i].mUserCount == 0) {
  92         PROFILER_UNREGISTER_THREAD();
  93         threadIds->RemoveElementAt(i);
  94       }
  95       return;
  96     }
  97   }
  98   MOZ_ASSERT_UNREACHABLE("Current thread was not registered");
  99 }
 100
 101 }  // namespace mozilla