Bug 1110485 P4 Keep Cache Actors alive during async operations. r=baku

dom/cache/CacheStreamControlChild.cpp

@@ -41,6 +41,7 @@ DeallocPCacheStreamControlChild(PCacheStreamControlChild* aActor)
 
 CacheStreamControlChild::CacheStreamControlChild()
   : mDestroyStarted(false)
+  , mDestroyDelayed(false)
 {
   MOZ_COUNT_CTOR(cache::CacheStreamControlChild);
 }
@@ -63,6 +64,21 @@ CacheStreamControlChild::StartDestroy()
   }
   mDestroyStarted = true;
 
+  // If any of the streams have started to be read, then wait for them to close
+  // naturally.
+  if (HasEverBeenRead()) {
+    // Note that we are delaying so that we can re-check for active streams
+    // in NoteClosedAfterForget().
+    mDestroyDelayed = true;
+    return;
+  }
+
+  // Otherwise, if the streams have not been touched then just pre-emptively
+  // close them now.  This handles the case where someone retrieves a Response
+  // from the Cache, but never accesses the body.  We should not keep the
+  // Worker alive until that Response is GC'd just because of its ignored
+  // body stream.
+
   // Begin shutting down all streams.  This is the same as if the parent had
   // asked us to shutdown.  So simulate the CloseAll IPC message.
   RecvCloseAll();
@@ -120,6 +136,15 @@ CacheStreamControlChild::NoteClosedAfterForget(const nsID& aId)
 {
   NS_ASSERT_OWNINGTHREAD(CacheStreamControlChild);
   unused << SendNoteClosed(aId);
+
+  // A stream has closed.  If we delayed StartDestry() due to this stream
+  // being read, then we should check to see if any of the remaining streams
+  // are active.  If none of our other streams have been read, then we can
+  // proceed with the shutdown now.
+  if (mDestroyDelayed && !HasEverBeenRead()) {
+    mDestroyDelayed = false;
+    RecvCloseAll();
+  }
 }
 
 #ifdef DEBUG