Bug 1345251 Make MozPromise usable on worker threads. r=gerald

dom/workers/RuntimeService.cpp

@@ -26,6 +26,7 @@
 #include "BackgroundChild.h"
 #include "GeckoProfiler.h"
 #include "jsfriendapi.h"
+#include "mozilla/AbstractThread.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/Atomics.h"
@@ -2816,10 +2817,12 @@ WorkerThreadPrimaryRunnable::Run()
   {
     // Raw pointer: this class is on the stack.
     WorkerPrivate* mWorkerPrivate;
+    RefPtr<AbstractThread> mAbstractThread;
 
   public:
     SetThreadHelper(WorkerPrivate* aWorkerPrivate, WorkerThread* aThread)
       : mWorkerPrivate(aWorkerPrivate)
+      , mAbstractThread(AbstractThread::CreateXPCOMThreadWrapper(NS_GetCurrentThread(), false))
     {
       MOZ_ASSERT(aWorkerPrivate);
       MOZ_ASSERT(aThread);

xpcom/threads/AbstractThread.cpp

@@ -128,7 +128,25 @@ private:
     return runner.forget();
   }
 
-  class Runner : public Runnable {
+  class Runner : public CancelableRunnable {
+    class MOZ_STACK_CLASS AutoTaskGuard final {
+    public:
+      explicit AutoTaskGuard(EventTargetWrapper* aThread)
+        : mLastCurrentThread(nullptr)
+      {
+        MOZ_ASSERT(aThread);
+        mLastCurrentThread = sCurrentThreadTLS.get();
+        sCurrentThreadTLS.set(aThread);
+      }
+
+      ~AutoTaskGuard()
+      {
+        sCurrentThreadTLS.set(mLastCurrentThread);
+      }
+    private:
+      AbstractThread* mLastCurrentThread;
+    };
+
   public:
     explicit Runner(EventTargetWrapper* aThread,
                     already_AddRefed<nsIRunnable> aRunnable,
@@ -141,23 +159,7 @@ private:
 
     NS_IMETHOD Run() override
     {
-      class MOZ_STACK_CLASS AutoTaskGuard final {
-      public:
-        explicit AutoTaskGuard(EventTargetWrapper* aThread)
-          : mLastCurrentThread(nullptr)
-        {
-          MOZ_ASSERT(aThread);
-          mLastCurrentThread = sCurrentThreadTLS.get();
-          sCurrentThreadTLS.set(aThread);
-        }
-
-        ~AutoTaskGuard()
-        {
-          sCurrentThreadTLS.set(mLastCurrentThread);
-        }
-      private:
-        AbstractThread* mLastCurrentThread;
-      } taskGuard(mThread);
+      AutoTaskGuard taskGuard(mThread);
 
       MOZ_ASSERT(mThread == AbstractThread::GetCurrent());
       MOZ_ASSERT(mThread->IsCurrentThreadIn());
@@ -170,6 +172,23 @@ private:
       return rv;
     }
 
+    nsresult Cancel() override
+    {
+      // Set the TLS during Cancel() just in case it calls Run().
+      AutoTaskGuard taskGuard(mThread);
+
+      nsresult rv = NS_OK;
+
+      // Try to cancel the runnable if it implements the right interface.
+      // Otherwise just skip the runnable.
+      nsCOMPtr<nsICancelableRunnable> cr = do_QueryInterface(mRunnable);
+      if (cr) {
+        rv = cr->Cancel();
+      }
+
+      return rv;
+    }
+
     NS_IMETHOD GetName(nsACString& aName) override
     {
       aName.AssignLiteral("AbstractThread::Runner");
@@ -265,6 +284,15 @@ already_AddRefed<AbstractThread>
 AbstractThread::CreateXPCOMThreadWrapper(nsIThread* aThread, bool aRequireTailDispatch)
 {
   RefPtr<EventTargetWrapper> wrapper = new EventTargetWrapper(aThread, aRequireTailDispatch);
+
+  bool onCurrentThread = false;
+  Unused << aThread->IsOnCurrentThread(&onCurrentThread);
+
+  if (onCurrentThread) {
+    sCurrentThreadTLS.set(wrapper);
+    return wrapper.forget();
+  }
+
   // Set the thread-local sCurrentThreadTLS to point to the wrapper on the
   // target thread. This ensures that sCurrentThreadTLS is as expected by
   // AbstractThread::GetCurrent() on the target thread.

xpcom/threads/MozPromise.h

@@ -316,7 +316,7 @@ protected:
     static const uint32_t sMagic = 0xfadece11;
 
   public:
-    class ResolveOrRejectRunnable : public Runnable
+    class ResolveOrRejectRunnable : public CancelableRunnable
     {
     public:
       ResolveOrRejectRunnable(ThenValueBase* aThenValue, MozPromise* aPromise)
@@ -342,6 +342,11 @@ protected:
         return NS_OK;
       }
 
+      nsresult Cancel() override
+      {
+        return Run();
+      }
+
     private:
       RefPtr<ThenValueBase> mThenValue;
       RefPtr<MozPromise> mPromise;
@@ -1218,7 +1223,7 @@ private:
 
 template<typename PromiseType, typename MethodType, typename ThisType,
          typename... Storages>
-class ProxyRunnable : public Runnable
+class ProxyRunnable : public CancelableRunnable
 {
 public:
   ProxyRunnable(typename PromiseType::Private* aProxyPromise,
@@ -1233,6 +1238,11 @@ public:
     return NS_OK;
   }
 
+  nsresult Cancel() override
+  {
+    return Run();
+  }
+
 private:
   RefPtr<typename PromiseType::Private> mProxyPromise;
   nsAutoPtr<MethodCall<PromiseType, MethodType, ThisType, Storages...>> mMethodCall;
@@ -1324,7 +1334,7 @@ InvokeAsync(AbstractThread* aTarget, ThisType* aThisVal, const char* aCallerName
 namespace detail {
 
 template<typename Function, typename PromiseType>
-class ProxyFunctionRunnable : public Runnable
+class ProxyFunctionRunnable : public CancelableRunnable
 {
   typedef typename Decay<Function>::Type FunctionStorage;
 public:
@@ -1342,6 +1352,11 @@ public:
     return NS_OK;
   }
 
+  nsresult Cancel() override
+  {
+    return Run();
+  }
+
 private:
   RefPtr<typename PromiseType::Private> mProxyPromise;
   UniquePtr<FunctionStorage> mFunction;