Bug 700835 - Restore plugin caching to work around bad crash bug in latest Apple Java updates. r=josh

dom/plugins/base/nsNPAPIPlugin.cpp

@@ -2485,9 +2485,8 @@ _setvalue(NPP npp, NPPVariable variable, void *result)
       }
 
     case NPPVpluginKeepLibraryInMemory: {
-      // This variable is not supported any more but we'll pretend it is
-      // so that plugins don't fail on an error return.
-      return NS_OK;
+      NPBool bCached = (result != nsnull);
+      return inst->SetCached(bCached);
     }
 
     case NPPVpluginUsesDOMForCursorBool: {

dom/plugins/base/nsNPAPIPluginInstance.cpp

@@ -100,6 +100,7 @@ nsNPAPIPluginInstance::nsNPAPIPluginInstance(nsNPAPIPlugin* plugin)
     mWindowless(false),
     mWindowlessLocal(false),
     mTransparent(false),
+    mCached(false),
     mUsesDOMForCursor(false),
     mInPluginInitCall(false),
     mPlugin(plugin),
@@ -167,6 +168,12 @@ nsNPAPIPluginInstance::Destroy()
   mPlugin = nsnull;
 }
 
+TimeStamp
+nsNPAPIPluginInstance::StopTime()
+{
+  return mStopTime;
+}
+
 nsresult nsNPAPIPluginInstance::Initialize(nsIPluginInstanceOwner* aOwner, const char* aMIMEType)
 {
   PLUGIN_LOG(PLUGIN_LOG_NORMAL, ("nsNPAPIPluginInstance::Initialize this=%p\n",this));
@@ -225,6 +232,7 @@ nsresult nsNPAPIPluginInstance::Stop()
   {
     AsyncCallbackAutoLock lock;
     mRunning = DESTROYING;
+    mStopTime = TimeStamp::Now();
   }
 
   OnPluginDestroy(&mNPP);
@@ -955,6 +963,19 @@ nsNPAPIPluginInstance::DefineJavaProperties()
   return NS_OK;
 }
 
+nsresult
+nsNPAPIPluginInstance::SetCached(bool aCache)
+{
+  mCached = aCache;
+  return NS_OK;
+}
+
+bool
+nsNPAPIPluginInstance::ShouldCache()
+{
+  return mCached;
+}
+
 nsresult
 nsNPAPIPluginInstance::IsWindowless(bool* isWindowless)
 {

dom/plugins/base/nsNPAPIPluginInstance.h

@@ -102,6 +102,7 @@ public:
   nsresult IsRemoteDrawingCoreAnimation(bool* aDrawing);
   nsresult GetJSObject(JSContext *cx, JSObject** outObject);
   nsresult DefineJavaProperties();
+  bool ShouldCache();
   nsresult IsWindowless(bool* isWindowless);
   nsresult AsyncSetWindow(NPWindow* window);
   nsresult GetImage(ImageContainer* aContainer, Image** aImage);
@@ -187,6 +188,12 @@ public:
     return mRunning == RUNNING || mRunning == DESTROYING;
   }
 
+  // return is only valid when the plugin is not running
+  mozilla::TimeStamp StopTime();
+
+  // cache this NPAPI plugin
+  nsresult SetCached(bool aCache);
+
   already_AddRefed<nsPIDOMWindow> GetDOMWindow();
 
   nsresult PrivateModeStateChanged();
@@ -246,6 +253,7 @@ protected:
   bool mWindowless;
   bool mWindowlessLocal;
   bool mTransparent;
+  bool mCached;
   bool mUsesDOMForCursor;
 
 public:
@@ -274,6 +282,10 @@ private:
   // non-null during a HandleEvent call
   void* mCurrentPluginEvent;
 
+  // Timestamp for the last time this plugin was stopped.
+  // This is only valid when the plugin is actually stopped!
+  mozilla::TimeStamp mStopTime;
+
   nsCOMPtr<nsIURI> mURI;
 
   bool mUsePluginLayersPref;

dom/plugins/base/nsPluginHost.cpp

@@ -231,6 +231,10 @@ PRLogModuleInfo* nsPluginLogging::gPluginLog = nsnull;
 #define BRAND_PROPERTIES_URL "chrome://branding/locale/brand.properties"
 #define PLUGIN_PROPERTIES_URL "chrome://global/locale/downloadProgress.properties"
 
+// #defines for plugin cache and prefs
+#define NS_PREF_MAX_NUM_CACHED_INSTANCES "browser.plugins.max_num_cached_plugins"
+#define DEFAULT_NUMBER_OF_STOPPED_INSTANCES 10
+
 #ifdef CALL_SAFETY_ON
 // By default we run OOPP, so we don't want to cover up crashes.
 bool gSkipPluginSafeCalls = true;
@@ -3204,13 +3208,34 @@ nsPluginHost::StopPluginInstance(nsNPAPIPluginInstance* aInstance)
     return NS_OK;
   }
 
-  nsPluginTag* pluginTag = TagForPlugin(aInstance->GetPlugin());
-
   aInstance->Stop();
-  aInstance->Destroy();
-  mInstances.RemoveElement(aInstance);
 
-  OnPluginInstanceDestroyed(pluginTag);
+  // if the instance does not want to be 'cached' just remove it
+  bool doCache = aInstance->ShouldCache();
+  if (doCache) {
+    // try to get the max cached instances from a pref or use default
+    PRUint32 cachedInstanceLimit;
+    nsresult rv = NS_ERROR_FAILURE;
+    if (mPrefService)
+      rv = mPrefService->GetIntPref(NS_PREF_MAX_NUM_CACHED_INSTANCES, (int*)&cachedInstanceLimit);
+    if (NS_FAILED(rv))
+      cachedInstanceLimit = DEFAULT_NUMBER_OF_STOPPED_INSTANCES;
+    
+    if (StoppedInstanceCount() >= cachedInstanceLimit) {
+      nsNPAPIPluginInstance *oldestInstance = FindOldestStoppedInstance();
+      if (oldestInstance) {
+        nsPluginTag* pluginTag = TagForPlugin(oldestInstance->GetPlugin());
+        oldestInstance->Destroy();
+        mInstances.RemoveElement(oldestInstance);
+        OnPluginInstanceDestroyed(pluginTag);
+      }
+    }
+  } else {
+    nsPluginTag* pluginTag = TagForPlugin(aInstance->GetPlugin());
+    aInstance->Destroy();
+    mInstances.RemoveElement(aInstance);
+    OnPluginInstanceDestroyed(pluginTag);
+  }
 
   return NS_OK;
 }
@@ -3936,6 +3961,38 @@ nsPluginHost::FindInstance(const char *mimetype)
   return nsnull;
 }
 
+nsNPAPIPluginInstance*
+nsPluginHost::FindOldestStoppedInstance()
+{
+  nsNPAPIPluginInstance *oldestInstance = nsnull;
+  TimeStamp oldestTime = TimeStamp::Now();
+  for (PRUint32 i = 0; i < mInstances.Length(); i++) {
+    nsNPAPIPluginInstance *instance = mInstances[i];
+    if (instance->IsRunning())
+      continue;
+
+    TimeStamp time = instance->StopTime();
+    if (time < oldestTime) {
+      oldestTime = time;
+      oldestInstance = instance;
+    }
+  }
+
+  return oldestInstance;
+}
+
+PRUint32
+nsPluginHost::StoppedInstanceCount()
+{
+  PRUint32 stoppedCount = 0;
+  for (PRUint32 i = 0; i < mInstances.Length(); i++) {
+    nsNPAPIPluginInstance *instance = mInstances[i];
+    if (!instance->IsRunning())
+      stoppedCount++;
+  }
+  return stoppedCount;
+}
+
 nsTArray< nsRefPtr<nsNPAPIPluginInstance> >*
 nsPluginHost::InstanceArray()
 {

dom/plugins/base/nsPluginHost.h

@@ -205,6 +205,8 @@ public:
                      const nsAString& browserDumpID);
 
   nsNPAPIPluginInstance *FindInstance(const char *mimetype);
+  nsNPAPIPluginInstance *FindOldestStoppedInstance();
+  PRUint32 StoppedInstanceCount();
 
   nsTArray< nsRefPtr<nsNPAPIPluginInstance> > *InstanceArray();
 
@@ -253,6 +255,9 @@ private:
   nsPluginTag*
   FindPluginEnabledForExtension(const char* aExtension, const char* &aMimeType);
 
+  nsresult
+  FindStoppedPluginForURL(nsIURI* aURL, nsIPluginInstanceOwner *aOwner);
+
   nsresult
   FindPlugins(bool aCreatePluginList, bool * aPluginsChanged);