Bug 620660 - Ensure the disk-cache stays around until all cache-operations have finished. r=michal.novotny a=jst

netwerk/cache/nsCacheService.cpp

@@ -268,6 +268,23 @@ private:
     PRInt32 mSmartSize;
 };
 
+class nsBlockOnCacheThreadEvent : public nsRunnable {
+public:
+    nsBlockOnCacheThreadEvent()
+    {
+    }
+    NS_IMETHOD Run()
+    {
+        mozilla::MonitorAutoEnter
+            autoMonitor(nsCacheService::gService->mMonitor);
+#ifdef PR_LOGGING
+        CACHE_LOG_DEBUG(("nsBlockOnCacheThreadEvent [%p]\n", this));
+#endif
+        autoMonitor.Notify();
+        return NS_OK;
+    }
+};
+
 
 nsresult
 nsCacheProfilePrefObserver::Install()
@@ -789,6 +806,33 @@ nsCacheService::DispatchToCacheIOThread(nsIRunnable* event)
     return gService->mCacheIOThread->Dispatch(event, NS_DISPATCH_NORMAL);
 }
 
+nsresult
+nsCacheService::SyncWithCacheIOThread()
+{
+    NS_ASSERTION(gService->mLockedThread == PR_GetCurrentThread(),
+                 "not holding cache-lock");
+    if (!gService->mCacheIOThread) return NS_ERROR_NOT_AVAILABLE;
+
+    mozilla::MonitorAutoEnter autoMonitor(gService->mMonitor);
+
+    nsCOMPtr<nsIRunnable> event = new nsBlockOnCacheThreadEvent();
+
+    // dispatch event - it will notify the monitor when it's done
+    nsresult rv =
+        gService->mCacheIOThread->Dispatch(event, NS_DISPATCH_NORMAL);
+    if (NS_FAILED(rv)) {
+        NS_WARNING("Failed dispatching block-event");
+        return NS_ERROR_UNEXPECTED;
+    }
+
+    Unlock();
+    // wait until notified, then return
+    rv = autoMonitor.Wait();
+    Lock();
+
+    return rv;
+}
+
 
 PRBool
 nsCacheProfilePrefObserver::DiskCacheEnabled()
@@ -942,6 +986,7 @@ NS_IMPL_THREADSAFE_ISUPPORTS1(nsCacheService, nsICacheService)
 
 nsCacheService::nsCacheService()
     : mLock(nsnull),
+      mMonitor("block-on-cache-monitor"),
       mInitialized(PR_FALSE),
       mEnableMemoryDevice(PR_TRUE),
       mEnableDiskDevice(PR_TRUE),
@@ -1046,6 +1091,10 @@ nsCacheService::Shutdown()
         ClearDoomList();
         ClearActiveEntries();
 
+        // Make sure to wait for any pending cache-operations before
+        // proceeding with destructive actions (bug #620660)
+        (void) SyncWithCacheIOThread();
+        
         // deallocate memory and disk caches
         delete mMemoryDevice;
         mMemoryDevice = nsnull;
@@ -1920,6 +1969,10 @@ nsCacheService::OnProfileShutdown(PRBool cleanse)
     gService->DoomActiveEntries();
     gService->ClearDoomList();
 
+    // Make sure to wait for any pending cache-operations before
+    // proceeding with destructive actions (bug #620660)
+    (void) SyncWithCacheIOThread();
+
 #ifdef NECKO_DISK_CACHE
     if (gService->mDiskDevice && gService->mEnableDiskDevice) {
         if (cleanse)

netwerk/cache/nsCacheService.h

@@ -56,6 +56,7 @@
 #include "nsString.h"
 #include "nsProxiedService.h"
 #include "nsTArray.h"
+#include "mozilla/Monitor.h"
 
 class nsCacheRequest;
 class nsCacheProfilePrefObserver;
@@ -145,6 +146,11 @@ public:
 
     static nsresult DispatchToCacheIOThread(nsIRunnable* event);
 
+    // Calling this method will block the calling thread until all pending
+    // events on the cache-io thread has finished. The calling thread must
+    // hold the cache-lock
+    static nsresult SyncWithCacheIOThread();
+
 
     /**
      * Methods called by nsCacheProfilePrefObserver
@@ -171,6 +177,7 @@ private:
     friend class nsOfflineCacheDevice;
     friend class nsProcessRequestEvent;
     friend class nsSetSmartSizeEvent;
+    friend class nsBlockOnCacheThreadEvent;
 
     /**
      * Internal Methods
@@ -249,6 +256,8 @@ private:
     
     PRLock *                        mLock;
 
+    mozilla::Monitor                mMonitor;
+
 #if defined(DEBUG)
     PRThread *                      mLockedThread;  // The thread holding mLock
 #endif

netwerk/cache/nsDiskCacheDevice.cpp

@@ -426,6 +426,11 @@ nsDiskCacheDevice::Shutdown_Private(PRBool  flush)
         // check cache limits in case we need to evict.
         EvictDiskCacheEntries(mCacheCapacity);
 
+        // At this point there may be a number of pending cache-requests on the
+        // cache-io thread. Wait for all these to run before we wipe out our
+        // datastructures (see bug #620660)
+        (void) nsCacheService::SyncWithCacheIOThread();
+
         // write out persistent information about the cache.
         (void) mCacheMap.Close(flush);