Bug 1192255: Clean up ContentParent's observer topics for the Nuwa pr…

…ocess. r=khuey --HG-- extra : rebase_source : 8350c348f79459ad04453be6a02b7c66a4e04b0a
mozilla · Aug 14, 2015 · 2c8c57b · 2c8c57b
1 parent 87e54b9
commit 2c8c57b
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Showing 4 changed files with 91 additions and 55 deletions.
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
@@ -2174,10 +2174,7 @@ bool
 ContentChild::RecvFlushMemory(const nsString& reason)
 {
 #ifdef MOZ_NUWA_PROCESS
-    if (IsNuwaProcess()) {
-        // Don't flush memory in the nuwa process: the GC thread could be frozen.
-        return true;
-    }
+    MOZ_ASSERT(!IsNuwaProcess() || !IsNuwaReady());
 #endif
     nsCOMPtr<nsIObserverService> os =
         mozilla::services::GetObserverService();
@@ -2416,11 +2413,7 @@ bool
 ContentChild::RecvMinimizeMemoryUsage()
 {
 #ifdef MOZ_NUWA_PROCESS
-    if (IsNuwaProcess()) {
-        // Don't minimize memory in the nuwa process: it will perform GC, but the
-        // GC thread could be frozen.
-        return true;
-    }
+    MOZ_ASSERT(!IsNuwaProcess() || !IsNuwaReady());
 #endif
     nsCOMPtr<nsIMemoryReporterManager> mgr =
         do_GetService("@mozilla.org/memory-reporter-manager;1");

diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
@@ -682,6 +682,22 @@ static const char* sObserverTopics[] = {
 #endif
 };
 
+#ifdef MOZ_NUWA_PROCESS
+// Contains the observer topics that can be sent to the Nuwa process after it
+// becomes ready. The ContentParent instance will unregister sObserverTopics
+// if not listed in sNuwaSafeObserverTopics.
+static const char* sNuwaSafeObserverTopics[] = {
+    "xpcom-shutdown",
+    "profile-before-change",
+#ifdef MOZ_WIDGET_GONK
+    "phone-state-changed",
+#endif
+#ifdef ACCESSIBILITY
+    "a11y-init-or-shutdown",
+#endif
+    "nsPref:Changed"
+};
+#endif
 /* static */ already_AddRefed<ContentParent>
 ContentParent::RunNuwaProcess()
 {
@@ -2923,6 +2939,41 @@ ContentParent::ForkNewProcess(bool aBlocking)
 #endif
 }
 
+#ifdef MOZ_NUWA_PROCESS
+// Keep only observer topics listed in sNuwaSafeObserverTopics and unregister
+// all the other registered topics.
+static void
+KeepNuwaSafeObserverTopics(ContentParent* aNuwaContentParent)
+{
+  MOZ_ASSERT(aNuwaContentParent && aNuwaContentParent->IsNuwaProcess());
+
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (!obs) {
+      return;
+  }
+
+  size_t topicLength = ArrayLength(sObserverTopics);
+  for (size_t i = 0; i < topicLength; ++i) {
+      bool nuwaSafe = false;
+      size_t safeTopicLength = ArrayLength(sNuwaSafeObserverTopics);
+
+      for (size_t j = 0; j < safeTopicLength; j++) {
+          if (!nsCRT::strcmp(sObserverTopics[i],
+                            sNuwaSafeObserverTopics[j])) {
+              // In the whitelist: don't need to unregister.
+              nuwaSafe = true;
+              break;
+          }
+      }
+
+      if (!nuwaSafe) {
+          obs->RemoveObserver(aNuwaContentParent, sObserverTopics[i]);
+      }
+  }
+
+}
+#endif
+
 void
 ContentParent::OnNuwaReady()
 {
@@ -2932,6 +2983,8 @@ ContentParent::OnNuwaReady()
     MOZ_ASSERT(IsNuwaProcess());
 
     sNuwaReady = true;
+    KeepNuwaSafeObserverTopics(this);
+
     PreallocatedProcessManager::OnNuwaReady();
     return;
 #else
@@ -3025,6 +3078,16 @@ ContentParent::Observe(nsISupports* aSubject,
     if (!mIsAlive || !mSubprocess)
         return NS_OK;
 
+    // The Nuwa process unregisters the topics after it becomes ready except for
+    // the ones listed in sNuwaSafeObserverTopics. If the topic needs to be
+    // observed by the Nuwa process, either for:
+    // 1. The topic is safe for the Nuwa process, either:
+    // 1.1 The state can safely happen (only run on the main thread) in the Nuwa
+    //     process (e.g. "a11y-init-or-shutdown"), or
+    // 1.2 The topic doesn't send an IPC message (e.g. "xpcom-shutdown").
+    // 2. The topic needs special handling (e.g. nsPref:Changed),
+    // add the topic to sNuwaSafeObserverTopics and then handle it if necessary.
+
     // listening for memory pressure event
     if (!strcmp(aTopic, "memory-pressure") &&
         !StringEndsWith(nsDependentString(aData),
@@ -3039,7 +3102,7 @@ ContentParent::Observe(nsISupports* aSubject,
         PrefSetting pref(strData, null_t(), null_t());
         Preferences::GetPreference(&pref);
 #ifdef MOZ_NUWA_PROCESS
-        if (IsNuwaProcess() && PreallocatedProcessManager::IsNuwaReady()) {
+        if (IsReadyNuwaProcess()) {
             // Don't send the pref update to the Nuwa process. Save the update
             // to send to the forked child.
             if (!sNuwaPrefUpdates) {
@@ -3056,28 +3119,16 @@ ContentParent::Observe(nsISupports* aSubject,
 #endif
     }
     else if (!strcmp(aTopic, NS_IPC_IOSERVICE_SET_OFFLINE_TOPIC)) {
-      NS_ConvertUTF16toUTF8 dataStr(aData);
-      const char *offline = dataStr.get();
-#ifdef MOZ_NUWA_PROCESS
-      if (!(IsNuwaReady() && IsNuwaProcess())) {
-#endif
-          if (!SendSetOffline(!strcmp(offline, "true") ? true : false)) {
-              return NS_ERROR_NOT_AVAILABLE;
-          }
-#ifdef MOZ_NUWA_PROCESS
-      }
-#endif
+        NS_ConvertUTF16toUTF8 dataStr(aData);
+        const char *offline = dataStr.get();
+        if (!SendSetOffline(!strcmp(offline, "true") ? true : false)) {
+            return NS_ERROR_NOT_AVAILABLE;
+        }
     }
     else if (!strcmp(aTopic, NS_IPC_IOSERVICE_SET_CONNECTIVITY_TOPIC)) {
-#ifdef MOZ_NUWA_PROCESS
-        if (!(IsNuwaReady() && IsNuwaProcess())) {
-#endif
-            if (!SendSetConnectivity(NS_LITERAL_STRING("true").Equals(aData))) {
-                return NS_ERROR_NOT_AVAILABLE;
-            }
-#ifdef MOZ_NUWA_PROCESS
+        if (!SendSetConnectivity(NS_LITERAL_STRING("true").Equals(aData))) {
+            return NS_ERROR_NOT_AVAILABLE;
         }
-#endif
     }
     // listening for alert notifications
     else if (!strcmp(aTopic, "alertfinished") ||
@@ -3103,13 +3154,7 @@ ContentParent::Observe(nsISupports* aSubject,
         nsCString creason;
         CopyUTF16toUTF8(aData, creason);
         DeviceStorageFile* file = static_cast<DeviceStorageFile*>(aSubject);
-
-#ifdef MOZ_NUWA_PROCESS
-        if (!(IsNuwaReady() && IsNuwaProcess()))
-#endif
-        {
-            unused << SendFilePathUpdate(file->mStorageType, file->mStorageName, file->mPath, creason);
-        }
+        unused << SendFilePathUpdate(file->mStorageType, file->mStorageName, file->mPath, creason);
     }
 #ifdef MOZ_WIDGET_GONK
     else if(!strcmp(aTopic, NS_VOLUME_STATE_CHANGED)) {
@@ -3142,27 +3187,17 @@ ContentParent::Observe(nsISupports* aSubject,
         vol->GetIsRemovable(&isRemovable);
         vol->GetIsHotSwappable(&isHotSwappable);
 
-#ifdef MOZ_NUWA_PROCESS
-        if (!(IsNuwaReady() && IsNuwaProcess()))
-#endif
-        {
-            unused << SendFileSystemUpdate(volName, mountPoint, state,
-                                           mountGeneration, isMediaPresent,
-                                           isSharing, isFormatting, isFake,
-                                           isUnmounting, isRemovable, isHotSwappable);
-        }
+        unused << SendFileSystemUpdate(volName, mountPoint, state,
+                                       mountGeneration, isMediaPresent,
+                                       isSharing, isFormatting, isFake,
+                                       isUnmounting, isRemovable, isHotSwappable);
     } else if (!strcmp(aTopic, "phone-state-changed")) {
         nsString state(aData);
         unused << SendNotifyPhoneStateChange(state);
     }
     else if(!strcmp(aTopic, NS_VOLUME_REMOVED)) {
-#ifdef MOZ_NUWA_PROCESS
-        if (!(IsNuwaReady() && IsNuwaProcess()))
-#endif
-        {
-            nsString volName(aData);
-            unused << SendVolumeRemoved(volName);
-        }
+        nsString volName(aData);
+        unused << SendVolumeRemoved(volName);
     }
 #endif
 #ifdef ACCESSIBILITY
@@ -4468,12 +4503,10 @@ ContentParent::DoSendAsyncMessage(JSContext* aCx,
     if (aCpows && (!mgr || !mgr->Wrap(aCx, aCpows, &cpows))) {
         return false;
     }
-#ifdef MOZ_NUWA_PROCESS
-    if (IsNuwaProcess() && IsNuwaReady()) {
+    if (IsReadyNuwaProcess()) {
         // Nuwa won't receive frame messages after it is frozen.
         return true;
     }
-#endif
     return SendAsyncMessage(nsString(aMessage), data, cpows, Principal(aPrincipal));
 }
 

diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
@@ -260,6 +260,15 @@ class ContentParent final : public PContentParent
     bool IsNuwaProcess();
 #endif
 
+    // A shorthand for checking if the Nuwa process is ready.
+    bool IsReadyNuwaProcess() {
+#ifdef MOZ_NUWA_PROCESS
+        return IsNuwaProcess() && IsNuwaReady();
+#else
+        return false;
+#endif
+    }
+
     GeckoChildProcessHost* Process() {
         return mSubprocess;
     }

diff --git a/ipc/glue/MessageLink.cpp b/ipc/glue/MessageLink.cpp
@@ -187,6 +187,7 @@ ProcessLink::SendMessage(Message *msg)
         case mozilla::dom::PNuwa::Msg_Fork__ID:
         case mozilla::dom::PNuwa::Reply_AddNewProcess__ID:
         case mozilla::dom::PContent::Msg_NotifyPhoneStateChange__ID:
+        case mozilla::dom::PContent::Msg_ActivateA11y__ID:
         case mozilla::hal_sandbox::PHal::Msg_NotifyNetworkChange__ID:
         case GOODBYE_MESSAGE_TYPE:
             break;