Bug 1035075 - Dispatch a runnable to wait for the PAC thread to shutdown. r=mcmanus

netwerk/base/src/nsPACMan.cpp

@@ -113,6 +113,30 @@ private:
   nsCOMPtr<nsIThread> mThread;
 };
 
+// Dispatch this to wait until the PAC thread shuts down.
+
+class WaitForThreadShutdown MOZ_FINAL : public nsRunnable
+{
+public:
+  explicit WaitForThreadShutdown(nsPACMan *aPACMan)
+    : mPACMan(aPACMan)
+  {
+  }
+
+  NS_IMETHODIMP Run()
+  {
+    NS_ABORT_IF_FALSE(NS_IsMainThread(), "wrong thread");
+    if (mPACMan->mPACThread) {
+      mPACMan->mPACThread->Shutdown();
+      mPACMan->mPACThread = nullptr;
+    }
+    return NS_OK;
+  }
+
+private:
+  nsRefPtr<nsPACMan> mPACMan;
+};
+
 //-----------------------------------------------------------------------------
 
 // PACLoadComplete allows the PAC thread to tell the main thread that
@@ -292,9 +316,15 @@ void
 nsPACMan::Shutdown()
 {
   NS_ABORT_IF_FALSE(NS_IsMainThread(), "pacman must be shutdown on main thread");
-  CancelExistingLoad();
+  if (mShutdown) {
+    return;
+  }
   mShutdown = true;
+  CancelExistingLoad();
   PostCancelPendingQ(NS_ERROR_ABORT);
+
+  nsRefPtr<WaitForThreadShutdown> runnable = new WaitForThreadShutdown(this);
+  NS_DispatchToMainThread(runnable);
 }
 
 nsresult
@@ -502,11 +532,12 @@ nsPACMan::ProcessPendingQ()
   NS_ABORT_IF_FALSE(!NS_IsMainThread(), "wrong thread");
   while (ProcessPending());
 
-  // do GC while the thread has nothing pending
-  mPAC.GC();
-
-  if (mShutdown)
+  if (mShutdown) {
     mPAC.Shutdown();
+  } else {
+    // do GC while the thread has nothing pending
+    mPAC.GC();
+  }
 }
 
 // returns true if progress was made by shortening the queue

netwerk/base/src/nsPACMan.h

@@ -24,6 +24,7 @@
 class nsPACMan;
 class nsISystemProxySettings;
 class nsIThread;
+class WaitForThreadShutdown;
 
 /**
  * This class defines a callback interface used by AsyncGetProxyForURI.
@@ -164,6 +165,7 @@ private:
   friend class PendingPACQuery;
   friend class PACLoadComplete;
   friend class ExecutePACThreadAction;
+  friend class WaitForThreadShutdown;
 
   ~nsPACMan();