Send worker-runnables destined for the main thread actually to the main thread.

A case of "one queue too many" here. Instead of worker runnables being sent to the main thread
where they are supposed to run, they are put in a task queue per-worker. This is devastating
for performance if many workers are running.

2 files changed, 18 insertions, 9 deletions

diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 612090027a..6bc5c4f963 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -404,7 +404,7 @@ private:
 
     RefPtr<MainThreadReleaseRunnable> runnable =
       new MainThreadReleaseRunnable(doomed, loadGroupToCancel);
-    if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
+    if (NS_FAILED(NS_DispatchToMainThread(runnable))) {
       NS_WARNING("Failed to dispatch, going to leak!");
     }
 
@@ -4078,7 +4078,7 @@ WorkerDebugger::PostMessageToDebugger(const nsAString& aMessage)
 
   RefPtr<PostDebuggerMessageRunnable> runnable =
     new PostDebuggerMessageRunnable(this, aMessage);
-  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
+  if (NS_FAILED(NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL))) {
     NS_WARNING("Failed to post message to debugger on main thread!");
   }
 }
@@ -4103,7 +4103,7 @@ WorkerDebugger::ReportErrorToDebugger(const nsAString& aFilename,
 
   RefPtr<ReportDebuggerErrorRunnable> runnable =
     new ReportDebuggerErrorRunnable(this, aFilename, aLineno, aMessage);
-  if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable.forget()))) {
+  if (NS_FAILED(NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL))) {
     NS_WARNING("Failed to report error to debugger on main thread!");
   }
 }
@@ -4862,7 +4862,7 @@ WorkerPrivate::MaybeDispatchLoadFailedRunnable()
     return;
   }
 
-  MOZ_ALWAYS_SUCCEEDS(DispatchToMainThread(runnable.forget()));
+  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable.forget()));
 }
 
 nsIEventTarget*
@@ -5083,7 +5083,7 @@ WorkerPrivate::ScheduleDeletion(WorkerRanOrNot aRanOrNot)
   else {
     RefPtr<TopLevelWorkerFinishedRunnable> runnable =
       new TopLevelWorkerFinishedRunnable(this);
-    if (NS_FAILED(DispatchToMainThread(runnable.forget()))) {
+    if (NS_FAILED(NS_DispatchToMainThread(runnable))) {
       NS_WARNING("Failed to dispatch runnable!");
     }
   }
diff --git a/dom/workers/WorkerRunnable.cpp b/dom/workers/WorkerRunnable.cpp
index 9e6d4cfb8f..60d69d4e42 100644
--- a/dom/workers/WorkerRunnable.cpp
+++ b/dom/workers/WorkerRunnable.cpp
@@ -117,7 +117,10 @@ WorkerRunnable::DispatchInternal()
     return NS_SUCCEEDED(parent->Dispatch(runnable.forget()));
   }
 
-  return NS_SUCCEEDED(mWorkerPrivate->DispatchToMainThread(runnable.forget()));
+  nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
+  MOZ_ASSERT(mainThread);
+
+  return NS_SUCCEEDED(mainThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL));
 }
 
 void
@@ -553,7 +556,10 @@ WorkerControlRunnable::DispatchInternal()
     return NS_SUCCEEDED(parent->DispatchControlRunnable(runnable.forget()));
   }
 
-  return NS_SUCCEEDED(mWorkerPrivate->DispatchToMainThread(runnable.forget()));
+  nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
+  MOZ_ASSERT(mainThread);
+
+  return NS_SUCCEEDED(mainThread->Dispatch(runnable.forget(), NS_DISPATCH_NORMAL));
 }
 
 NS_IMPL_ISUPPORTS_INHERITED0(WorkerControlRunnable, WorkerRunnable)
@@ -580,7 +586,10 @@ WorkerMainThreadRunnable::Dispatch(Status aFailStatus, ErrorResult& aRv)
     return;
   }
 
-  DebugOnly<nsresult> rv = mWorkerPrivate->DispatchToMainThread(this);
+  RefPtr<WorkerMainThreadRunnable> runnable(this);
+
+  DebugOnly<nsresult> rv =
+    NS_DispatchToMainThread(runnable.forget(), NS_DISPATCH_NORMAL);
   MOZ_ASSERT(NS_SUCCEEDED(rv),
              "Should only fail after xpcom-shutdown-threads and we're gone by then");
 
@@ -670,7 +679,7 @@ WorkerProxyToMainThreadRunnable::Dispatch()
     return false;
   }
 
-  if (NS_WARN_IF(NS_FAILED(mWorkerPrivate->DispatchToMainThread(this)))) {
+  if (NS_WARN_IF(NS_FAILED(NS_DispatchToMainThread(this)))) {
     ReleaseWorker();
     RunBackOnWorkerThread();
     return false;