Bug 829419 - Don't allow processing pending events while shutting down cache IO thread, r=jduell

netwerk/cache/Makefile.in

@@ -28,6 +28,7 @@ CPPSRCS = \
   nsCacheMetaData.cpp \
   nsCacheService.cpp \
   nsCacheSession.cpp \
+  nsCacheUtils.cpp \
   nsMemoryCacheDevice.cpp \
   nsDiskCacheBinding.cpp \
   nsDiskCacheBlockFile.cpp \

netwerk/cache/nsCacheService.cpp

@@ -20,6 +20,7 @@
 #include "nsICacheVisitor.h"
 #include "nsDiskCacheDevice.h"
 #include "nsDiskCacheDeviceSQL.h"
+#include "nsCacheUtils.h"
 
 #include "nsIObserverService.h"
 #include "nsIPrefService.h"
@@ -1254,7 +1255,7 @@ nsCacheService::Shutdown()
     }
 
     if (cacheIOThread)
-        cacheIOThread->Shutdown();
+        nsShutdownThread::BlockingShutdown(cacheIOThread);
 
     if (shouldSanitize) {
         nsresult rv = parentDir->AppendNative(NS_LITERAL_CSTRING("Cache"));

netwerk/cache/nsCacheUtils.cpp

@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCache.h"
+#include "nsCacheUtils.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+
+class nsDestroyThreadEvent : public nsRunnable {
+public:
+  nsDestroyThreadEvent(nsIThread *thread)
+    : mThread(thread)
+  {}
+  NS_IMETHOD Run()
+  {
+    mThread->Shutdown();
+    return NS_OK;
+  }
+private:
+  nsCOMPtr<nsIThread> mThread;
+};
+
+nsShutdownThread::nsShutdownThread(nsIThread *aThread)
+  : mLock("nsShutdownThread.mLock")
+  , mCondVar(mLock, "nsShutdownThread.mCondVar")
+  , mThread(aThread)
+{
+}
+
+nsShutdownThread::~nsShutdownThread()
+{
+}
+
+nsresult
+nsShutdownThread::Shutdown(nsIThread *aThread)
+{
+  nsresult rv;
+  nsRefPtr<nsDestroyThreadEvent> ev = new nsDestroyThreadEvent(aThread);
+  rv = NS_DispatchToMainThread(ev);
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Dispatching event in nsShutdownThread::Shutdown failed!");
+  }
+  return rv;
+}
+
+nsresult
+nsShutdownThread::BlockingShutdown(nsIThread *aThread)
+{
+  nsresult rv;
+
+  nsRefPtr<nsShutdownThread> st = new nsShutdownThread(aThread);
+  nsCOMPtr<nsIThread> workerThread;
+
+  rv = NS_NewNamedThread("thread shutdown", getter_AddRefs(workerThread));
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Can't create nsShutDownThread worker thread!");
+    return rv;
+  }
+
+  {
+    MutexAutoLock lock(st->mLock);
+    rv = aThread->Dispatch(st, NS_DISPATCH_NORMAL);
+    if (NS_FAILED(rv)) {
+      NS_WARNING(
+        "Dispatching event in nsShutdownThread::BlockingShutdown failed!");
+    } else {
+      st->mCondVar.Wait();
+    }
+  }
+
+  return Shutdown(workerThread);
+}
+
+NS_IMETHODIMP
+nsShutdownThread::Run()
+{
+  MutexAutoLock lock(mLock);
+  mThread->Shutdown();
+  mCondVar.Notify();
+  return NS_OK;
+}

netwerk/cache/nsCacheUtils.h

@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _nsCacheUtils_h_
+#define _nsCacheUtils_h_
+
+#include "nsThreadUtils.h"
+#include "nsCOMPtr.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/CondVar.h"
+
+class nsIThread;
+
+/**
+ * A class with utility methods for shutting down nsIThreads easily.
+  */
+class nsShutdownThread : public nsRunnable {
+public:
+  nsShutdownThread(nsIThread *aThread);
+  ~nsShutdownThread();
+
+  NS_IMETHOD Run();
+
+/**
+ * Shutdown ensures that aThread->Shutdown() is called on a main thread
+ */
+  static nsresult Shutdown(nsIThread *aThread);
+
+/**
+ * BlockingShutdown ensures that by the time it returns, aThread->Shutdown() has
+ * been called and no pending events have been processed on the current thread.
+ */
+  static nsresult BlockingShutdown(nsIThread *aThread);
+
+private:
+  mozilla::Mutex      mLock;
+  mozilla::CondVar    mCondVar;
+  nsCOMPtr<nsIThread> mThread;
+};
+
+#endif

netwerk/cache/nsDeleteDir.cpp

@@ -13,6 +13,7 @@
 #include "nsAutoPtr.h"
 #include "nsThreadUtils.h"
 #include "nsISupportsPriority.h"
+#include "nsCacheUtils.h"
 #include <time.h>
 
 using namespace mozilla;
@@ -28,20 +29,6 @@ public:
   }
 };
 
-class nsDestroyThreadEvent : public nsRunnable {
-public:
-  nsDestroyThreadEvent(nsIThread *thread)
-    : mThread(thread)
-  {}
-  NS_IMETHOD Run()
-  {
-    mThread->Shutdown();
-    return NS_OK;
-  }
-private:
-  nsCOMPtr<nsIThread> mThread;
-};
-
 
 nsDeleteDir * nsDeleteDir::gInstance = nullptr;
 
@@ -155,7 +142,7 @@ nsDeleteDir::DestroyThread()
     // more work to do, so don't delete thread.
     return;
 
-  NS_DispatchToMainThread(new nsDestroyThreadEvent(mThread));
+  nsShutdownThread::Shutdown(mThread);
   mThread = nullptr;
 }