1 files changed, 156 insertions, 0 deletions
diff --git a/xpcom/threads/nsThreadManager.h b/xpcom/threads/nsThreadManager.h
new file mode 100644
index 0000000000..46e061a1ad
--- /dev/null
+++ b/xpcom/threads/nsThreadManager.h
@@ -0,0 +1,156 @@
+/* -*- Mode: C++; tab-width: 8; 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/. */
+
+#ifndef nsThreadManager_h__
+#define nsThreadManager_h__
+
+#include "nsIThreadManager.h"
+#include "nsThread.h"
+#include "mozilla/ShutdownPhase.h"
+
+class nsIRunnable;
+class nsIThread;
+
+namespace mozilla {
+class IdleTaskManager;
+class SynchronizedEventQueue;
+class TaskQueue;
+
+template <typename T>
+class NeverDestroyed;
+}  // namespace mozilla
+
+class BackgroundEventTarget;
+
+class nsThreadManager : public nsIThreadManager {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITHREADMANAGER
+
+  static nsThreadManager& get();
+
+  nsresult Init();
+
+  // Shutdown all threads other than the main thread.  This function should only
+  // be called on the main thread of the application process.
+  void ShutdownNonMainThreads();
+
+  // Finish shutting down all threads. This function must be called after
+  // ShutdownNonMainThreads and will delete the BackgroundEventTarget and
+  // take the main thread event target out of commission, but without
+  // releasing the underlying nsThread object.
+  void ShutdownMainThread();
+
+  // Release the underlying main thread nsThread object.
+  void ReleaseMainThread();
+
+  // Called by nsThread to inform the ThreadManager it exists.  This method
+  // must be called when the given thread is the current thread.
+  void RegisterCurrentThread(nsThread& aThread);
+
+  // Called by nsThread to inform the ThreadManager it is going away.  This
+  // method must be called when the given thread is the current thread.
+  void UnregisterCurrentThread(nsThread& aThread);
+
+  // Returns the current thread.  Returns null if OOM or if ThreadManager isn't
+  // initialized.  Creates the nsThread if one does not exist yet.
+  nsThread* GetCurrentThread();
+
+  // Returns true iff the currently running thread has an nsThread associated
+  // with it (ie; whether this is a thread that we can dispatch runnables to).
+  bool IsNSThread() const;
+
+  // CreateCurrentThread sets up an nsThread for the current thread. It uses the
+  // event queue and main thread flags passed in. It should only be called once
+  // for the current thread. After it returns, GetCurrentThread() will return
+  // the thread that was created. GetCurrentThread() will also create a thread
+  // (lazily), but it doesn't allow the queue or main-thread attributes to be
+  // specified.
+  nsThread* CreateCurrentThread(mozilla::SynchronizedEventQueue* aQueue);
+
+  nsresult DispatchToBackgroundThread(nsIRunnable* aEvent,
+                                      uint32_t aDispatchFlags);
+
+  already_AddRefed<mozilla::TaskQueue> CreateBackgroundTaskQueue(
+      const char* aName);
+
+  ~nsThreadManager();
+
+  void EnableMainThreadEventPrioritization();
+  void FlushInputEventPrioritization();
+  void SuspendInputEventPrioritization();
+  void ResumeInputEventPrioritization();
+
+  static bool MainThreadHasPendingHighPriorityEvents();
+
+  nsIThread* GetMainThreadWeak() { return mMainThread; }
+
+  // Low level methods for interacting with the global thread list. Be very
+  // careful when holding `ThreadListMutex()` as no new threads can be started
+  // while it is held.
+  mozilla::OffTheBooksMutex& ThreadListMutex() MOZ_RETURN_CAPABILITY(mMutex) {
+    return mMutex;
+  }
+
+  bool AllowNewXPCOMThreads() MOZ_EXCLUDES(mMutex);
+  bool AllowNewXPCOMThreadsLocked() MOZ_REQUIRES(mMutex) {
+    return mState == State::eActive;
+  }
+
+  mozilla::LinkedList<nsThread>& ThreadList() MOZ_REQUIRES(mMutex) {
+    return mThreadList;
+  }
+
+ private:
+  friend class mozilla::NeverDestroyed<nsThreadManager>;
+
+  nsThreadManager();
+
+  nsresult SpinEventLoopUntilInternal(
+      const nsACString& aVeryGoodReasonToDoThis,
+      nsINestedEventLoopCondition* aCondition,
+      mozilla::ShutdownPhase aShutdownPhaseToCheck);
+
+  static void ReleaseThread(void* aData);
+
+  enum class State : uint8_t {
+    // The thread manager has yet to be initialized.
+    eUninit,
+    // The thread manager is active, and operating normally.
+    eActive,
+    // The thread manager is in XPCOM shutdown. New calls to NS_NewNamedThread
+    // will fail, as all XPCOM threads are required to be shutting down.
+    eShutdown,
+  };
+
+  unsigned mCurThreadIndex;  // thread-local-storage index
+  RefPtr<nsThread> mMainThread;
+
+  mutable mozilla::OffTheBooksMutex mMutex;
+
+  // Current state in the thread manager's lifecycle. See docs above.
+  State mState MOZ_GUARDED_BY(mMutex);
+
+  // Global list of active nsThread instances, including both explicitly and
+  // implicitly created threads.
+  //
+  // NOTE: New entries to this list _may_ be added after mAllowNewThreads has
+  // been cleared, but only for implicitly created thread wrappers which are
+  // not shut down during XPCOM shutdown.
+  mozilla::LinkedList<nsThread> mThreadList MOZ_GUARDED_BY(mMutex);
+
+  // Shared event target used for background runnables.
+  RefPtr<BackgroundEventTarget> mBackgroundEventTarget MOZ_GUARDED_BY(mMutex);
+};
+
+#define NS_THREADMANAGER_CID                         \
+  { /* 7a4204c6-e45a-4c37-8ebb-6709a22c917c */       \
+    0x7a4204c6, 0xe45a, 0x4c37, {                    \
+      0x8e, 0xbb, 0x67, 0x09, 0xa2, 0x2c, 0x91, 0x7c \
+    }                                                \
+  }
+
+#endif  // nsThreadManager_h__