Bug 861894 - Avoid apps to schedule new offline cache downloads while device free space is low. r=honzab

uriloader/prefetch/nsOfflineCacheUpdate.cpp

@@ -1778,6 +1778,16 @@ nsOfflineCacheUpdate::Begin()
 
     mItemsInProgress = 0;
 
+    if (mState == STATE_CANCELLED) {
+      nsRefPtr<nsRunnableMethod<nsOfflineCacheUpdate> > errorNotification =
+        NS_NewRunnableMethod(this,
+                             &nsOfflineCacheUpdate::AsyncFinishWithError);
+      nsresult rv = NS_DispatchToMainThread(errorNotification);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      return NS_OK;
+    }
+
     if (mPartialUpdate) {
         mState = STATE_DOWNLOADING;
         NotifyState(nsIOfflineCacheUpdateObserver::STATE_DOWNLOADING);
@@ -2153,6 +2163,13 @@ nsOfflineCacheUpdate::Finish()
     return rv;
 }
 
+void
+nsOfflineCacheUpdate::AsyncFinishWithError()
+{
+    NotifyState(nsOfflineCacheUpdate::STATE_ERROR);
+    Finish();
+}
+
 static nsresult
 EvictOneOfCacheGroups(nsIApplicationCacheService *cacheService,
                       uint32_t count, const char * const *groups)

uriloader/prefetch/nsOfflineCacheUpdate.h

@@ -239,6 +239,8 @@ private:
     nsresult Finish();
     nsresult FinishNoNotify();
 
+    void AsyncFinishWithError();
+
     // Find one non-pinned cache group and evict it.
     nsresult EvictOneNonPinned();
 
@@ -355,6 +357,7 @@ private:
 
     bool mDisabled;
     bool mUpdateRunning;
+    bool mLowFreeSpace;
 };
 
 #endif

uriloader/prefetch/nsOfflineCacheUpdateService.cpp

@@ -46,6 +46,7 @@
 #include "nsIAsyncVerifyRedirectCallback.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Attributes.h"
+#include "nsIDiskSpaceWatcher.h"
 
 using namespace mozilla;
 
@@ -261,6 +262,7 @@ NS_IMPL_ISUPPORTS3(nsOfflineCacheUpdateService,
 nsOfflineCacheUpdateService::nsOfflineCacheUpdateService()
     : mDisabled(false)
     , mUpdateRunning(false)
+    , mLowFreeSpace(false)
 {
 }
 
@@ -288,6 +290,15 @@ nsOfflineCacheUpdateService::Init()
                                                true);
     NS_ENSURE_SUCCESS(rv, rv);
 
+    // Get the current status of the disk in terms of free space and observe
+    // low device storage notifications.
+    nsCOMPtr<nsIDiskSpaceWatcher> diskSpaceWatcherService =
+      do_GetService("@mozilla.org/toolkit/disk-space-watcher;1");
+    diskSpaceWatcherService->GetIsDiskFull(&mLowFreeSpace);
+
+    rv = observerService->AddObserver(this, "disk-space-watcher", false);
+    NS_ENSURE_SUCCESS(rv, rv);
+
     gOfflineCacheUpdateService = this;
 
     return NS_OK;
@@ -408,6 +419,11 @@ nsOfflineCacheUpdateService::ProcessNextUpdate()
 
     if (mUpdates.Length() > 0) {
         mUpdateRunning = true;
+        // Canceling the update before Begin() call will make the update
+        // asynchronously finish with an error.
+        if (mLowFreeSpace) {
+            mUpdates[0]->Cancel();
+        }
         return mUpdates[0]->Begin();
     }
 
@@ -599,6 +615,17 @@ nsOfflineCacheUpdateService::Observe(nsISupports     *aSubject,
         mDisabled = true;
     }
 
+    if (!strcmp(aTopic, "disk-space-watcher")) {
+        if (NS_LITERAL_STRING("full").Equals(aData)) {
+            mLowFreeSpace = true;
+            for (uint32_t i = 0; i < mUpdates.Length(); i++) {
+                mUpdates[i]->Cancel();
+            }
+        } else if (NS_LITERAL_STRING("free").Equals(aData)) {
+            mLowFreeSpace = false;
+        }
+    }
+
     return NS_OK;
 }