1 /* -*- Mode: C++; tab-width: 8; 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
5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 #ifndef nsThreadSyncDispatch_h_
8 #define nsThreadSyncDispatch_h_
9 
10 #include "nsThreadUtils.h"
11 #include "LeakRefPtr.h"
12 #include "mozilla/DebugOnly.h"
13 
14 class nsThreadSyncDispatch : public mozilla::Runnable
15 {
16 public:
nsThreadSyncDispatch(nsIThread * aOrigin,already_AddRefed<nsIRunnable> && aTask)17   nsThreadSyncDispatch(nsIThread* aOrigin, already_AddRefed<nsIRunnable>&& aTask)
18     : mOrigin(aOrigin)
19     , mSyncTask(mozilla::Move(aTask))
20   {
21   }
22 
IsPending()23   bool IsPending()
24   {
25     return !!mSyncTask;
26   }
27 
28 private:
Run()29   NS_IMETHOD Run() override
30   {
31     if (nsIRunnable* task = mSyncTask.get()) {
32       mozilla::DebugOnly<nsresult> result = task->Run();
33       MOZ_ASSERT(NS_SUCCEEDED(result),
34                  "task in sync dispatch should not fail");
35       // We must release the task here to ensure that when the original
36       // thread is unblocked, this task has been released.
37       mSyncTask.release();
38       // unblock the origin thread
39       mOrigin->Dispatch(this, NS_DISPATCH_NORMAL);
40     }
41     return NS_OK;
42   }
43 
44   nsCOMPtr<nsIThread> mOrigin;
45   // The task is leaked by default when Run() is not called, because
46   // otherwise we may release it in an incorrect thread.
47   mozilla::LeakRefPtr<nsIRunnable> mSyncTask;
48 };
49 
50 #endif // nsThreadSyncDispatch_h_
51