xpcom/threads/nsThread.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsThread_h__
   8 #define nsThread_h__
   9
  10 #include "mozilla/Mutex.h"
  11 #include "nsIThreadInternal.h"
  12 #include "nsISupportsPriority.h"
  13 #include "nsEventQueue.h"
  14 #include "nsThreadUtils.h"
  15 #include "nsString.h"
  16 #include "nsTObserverArray.h"
  17 #include "mozilla/Attributes.h"
  18
  19 // A native thread
  20 class nsThread MOZ_FINAL : public nsIThreadInternal,
  21                            public nsISupportsPriority
  22 {
  23 public:
  24   NS_DECL_THREADSAFE_ISUPPORTS
  25   NS_DECL_NSIEVENTTARGET
  26   NS_DECL_NSITHREAD
  27   NS_DECL_NSITHREADINTERNAL
  28   NS_DECL_NSISUPPORTSPRIORITY
  29
  30   enum MainThreadFlag {
  31     MAIN_THREAD,
  32     NOT_MAIN_THREAD
  33   };
  34
  35   nsThread(MainThreadFlag aMainThread, uint32_t aStackSize);
  36
  37   // Initialize this as a wrapper for a new PRThread.
  38   nsresult Init();
  39
  40   // Initialize this as a wrapper for the current PRThread.
  41   nsresult InitCurrentThread();
  42
  43   // The PRThread corresponding to this thread.
  44   PRThread *GetPRThread() { return mThread; }
  45
  46   // If this flag is true, then the nsThread was created using
  47   // nsIThreadManager::NewThread.
  48   bool ShutdownRequired() { return mShutdownRequired; }
  49
  50   // Clear the observer list.
  51   void ClearObservers() { mEventObservers.Clear(); }
  52
  53   static nsresult
  54   SetMainThreadObserver(nsIThreadObserver* aObserver);
  55
  56 private:
  57   static nsIThreadObserver* sMainThreadObserver;
  58
  59   friend class nsThreadShutdownEvent;
  60
  61   ~nsThread();
  62
  63   bool ShuttingDown() { return mShutdownContext != nullptr; }
  64
  65   static void ThreadFunc(void *arg);
  66
  67   // Helper
  68   already_AddRefed<nsIThreadObserver> GetObserver() {
  69     nsIThreadObserver *obs;
  70     nsThread::GetObserver(&obs);
  71     return already_AddRefed<nsIThreadObserver>(obs);
  72   }
  73
  74   // Wrappers for event queue methods:
  75   bool GetEvent(bool mayWait, nsIRunnable **event) {
  76     return mEvents.GetEvent(mayWait, event);
  77   }
  78   nsresult PutEvent(nsIRunnable *event);
  79
  80   // This lock protects access to mObserver, mEvents and mEventsAreDoomed.
  81   // All of those fields are only modified on the thread itself (never from
  82   // another thread).  This means that we can avoid holding the lock while
  83   // using mObserver and mEvents on the thread itself.  When calling PutEvent
  84   // on mEvents, we have to hold the lock to synchronize with PopEventQueue.
  85   mozilla::Mutex mLock;
  86
  87   nsCOMPtr<nsIThreadObserver> mObserver;
  88
  89   // Only accessed on the target thread.
  90   nsAutoTObserverArray<nsCOMPtr<nsIThreadObserver>, 2> mEventObservers;
  91
  92   nsEventQueue  mEvents;
  93
  94   int32_t   mPriority;
  95   PRThread *mThread;
  96   uint32_t  mRunningEvent;  // counter
  97   uint32_t  mStackSize;
  98
  99   struct nsThreadShutdownContext *mShutdownContext;
 100
 101   bool mShutdownRequired;
 102   // Set to true when events posted to this thread will never run.
 103   bool mEventsAreDoomed;
 104   MainThreadFlag mIsMainThread;
 105 };
 106
 107 //-----------------------------------------------------------------------------
 108
 109 class nsThreadSyncDispatch : public nsRunnable {
 110 public:
 111   nsThreadSyncDispatch(nsIThread *origin, nsIRunnable *task)
 112     : mOrigin(origin), mSyncTask(task), mResult(NS_ERROR_NOT_INITIALIZED) {
 113   }
 114
 115   bool IsPending() {
 116     return mSyncTask != nullptr;
 117   }
 118
 119   nsresult Result() {
 120     return mResult;
 121   }
 122
 123 private:
 124   NS_DECL_NSIRUNNABLE
 125
 126   nsCOMPtr<nsIThread> mOrigin;
 127   nsCOMPtr<nsIRunnable> mSyncTask;
 128   nsresult mResult;
 129 };
 130
 131 #endif  // nsThread_h__