1 files changed, 101 insertions, 0 deletions
diff --git a/dom/media/CallbackThreadRegistry.cpp b/dom/media/CallbackThreadRegistry.cpp
new file mode 100644
index 0000000000..f4d2af5bd1
--- /dev/null
+++ b/dom/media/CallbackThreadRegistry.cpp
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "CallbackThreadRegistry.h"
+#include "mozilla/ClearOnShutdown.h"
+
+namespace mozilla {
+struct CallbackThreadRegistrySingleton {
+  CallbackThreadRegistrySingleton()
+      : mRegistry(MakeUnique<CallbackThreadRegistry>()) {
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction(__func__, [registry = &mRegistry] {
+          const auto phase = ShutdownPhase::XPCOMShutdownFinal;
+          MOZ_DIAGNOSTIC_ASSERT(!PastShutdownPhase(phase));
+          ClearOnShutdown(registry, phase);
+        }));
+  }
+
+  UniquePtr<CallbackThreadRegistry> mRegistry;
+};
+
+CallbackThreadRegistry::CallbackThreadRegistry()
+    : mThreadIds("CallbackThreadRegistry::mThreadIds") {}
+
+/* static */
+CallbackThreadRegistry* CallbackThreadRegistry::Get() {
+  static CallbackThreadRegistrySingleton sSingleton;
+  return sSingleton.mRegistry.get();
+}
+
+static bool CanLeak() {
+#ifdef NS_BUILD_REFCNT_LOGGING
+  static const bool logging =
+      getenv("XPCOM_MEM_LEAK_LOG") || getenv("XPCOM_MEM_BLOAT_LOG") ||
+      getenv("XPCOM_MEM_REFCNT_LOG") || getenv("XPCOM_MEM_ALLOC_LOG") ||
+      getenv("XPCOM_MEM_COMPTR_LOG");
+  return logging;
+#else
+  return false;
+#endif
+}
+
+void CallbackThreadRegistry::Register(ProfilerThreadId aThreadId,
+                                      const char* aName) {
+  if (!aThreadId.IsSpecified()) {
+    // profiler_current_thread_id is unspecified on unsupported platforms.
+    return;
+  }
+
+  if (CanLeak()) {
+    NS_WARNING(
+        "Not registering callback thread due to refcount logging; it may show "
+        "up as a leak of the TLS-backed nsThread wrapper if the thread "
+        "outlives xpcom shutdown.");
+    return;
+  }
+
+  auto threadIds = mThreadIds.Lock();
+  for (uint32_t i = 0; i < threadIds->Length(); i++) {
+    if ((*threadIds)[i].mId == aThreadId) {
+      (*threadIds)[i].mUserCount++;
+      return;
+    }
+  }
+  ThreadUserCount tuc;
+  tuc.mId = aThreadId;
+  tuc.mUserCount = 1;
+  threadIds->AppendElement(tuc);
+  PROFILER_REGISTER_THREAD(aName);
+}
+
+void CallbackThreadRegistry::Unregister(ProfilerThreadId aThreadId) {
+  if (!aThreadId.IsSpecified()) {
+    // profiler_current_thread_id is unspedified on unsupported platforms.
+    return;
+  }
+
+  if (CanLeak()) {
+    return;
+  }
+
+  auto threadIds = mThreadIds.Lock();
+  for (uint32_t i = 0; i < threadIds->Length(); i++) {
+    if ((*threadIds)[i].mId == aThreadId) {
+      MOZ_ASSERT((*threadIds)[i].mUserCount > 0);
+      (*threadIds)[i].mUserCount--;
+
+      if ((*threadIds)[i].mUserCount == 0) {
+        PROFILER_UNREGISTER_THREAD();
+        threadIds->RemoveElementAt(i);
+      }
+      return;
+    }
+  }
+  MOZ_ASSERT_UNREACHABLE("Current thread was not registered");
+}
+
+}  // namespace mozilla