Bug 1438945 - Part 13: keeping ContentProcess alive. r=asuth,mrbkap

--HG--
extra : rebase_source : 10f03713c5f31f3a41e4f45cde367f5daaa5ebd8

dom/ipc/ContentParent.cpp

@@ -1862,6 +1862,11 @@ ContentParent::ShouldKeepProcessAlive() const
     return true;
   }
 
+  // If we have active workers, we need to stay alive.
+  if (mRemoteWorkerActors) {
+    return true;
+  }
+
   if (!sBrowserContentParents) {
     return false;
   }
@@ -2385,6 +2390,7 @@ ContentParent::ContentParent(ContentParent* aOpener,
   , mChildID(gContentChildID++)
   , mGeolocationWatchID(-1)
   , mJSPluginID(aJSPluginID)
+  , mRemoteWorkerActors(0)
   , mNumDestroyingTabs(0)
   , mIsAvailable(true)
   , mIsAlive(true)
@@ -6162,3 +6168,32 @@ ContentParent::RecvSetOpenerBrowsingContext(
 
   return IPC_OK();
 }
+
+void
+ContentParent::RegisterRemoteWorkerActor()
+{
+  ++mRemoteWorkerActors;
+}
+
+void
+ContentParent::UnregisterRemoveWorkerActor()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (--mRemoteWorkerActors) {
+    return;
+  }
+
+  ContentProcessManager* cpm = ContentProcessManager::GetSingleton();
+  if (!cpm->GetTabParentCountByProcessId(ChildID()) &&
+      !ShouldKeepProcessAlive() &&
+      !TryToRecycle()) {
+    // In the case of normal shutdown, send a shutdown message to child to
+    // allow it to perform shutdown tasks.
+    MessageLoop::current()->PostTask(
+      NewRunnableMethod<ShutDownMethod>("dom::ContentParent::ShutDownProcess",
+                                        this,
+                                        &ContentParent::ShutDownProcess,
+                                        SEND_SHUTDOWN_MESSAGE));
+  }
+}

dom/ipc/ContentParent.h

@@ -363,6 +363,15 @@ public:
                         const ContentParentId& aCpId,
                         bool aMarkedDestroying);
 
+  // This method can be called on any thread.
+  void
+  RegisterRemoteWorkerActor();
+
+  // This method _must_ be called on main-thread because it can start the
+  // shutting down of the content process.
+  void
+  UnregisterRemoveWorkerActor();
+
   void ReportChildAlreadyBlocked();
 
   bool RequestRunToCompletion();
@@ -1300,6 +1309,13 @@ private:
   // SIGSTOP), are still killed eventually.  This task enforces that
   // timer.
   nsCOMPtr<nsITimer> mForceKillTimer;
+
+  // Number of active remote workers. This value is increased when a
+  // RemoteWorkerParent actor is created for this ContentProcess and it is
+  // decreased when the actor is destroyed.
+  // It's touched on PBackground thread and on main-thread.
+  Atomic<uint32_t> mRemoteWorkerActors;
+
   // How many tabs we're waiting to finish their destruction
   // sequence.  Precisely, how many TabParents have called
   // NotifyTabDestroying() but not called NotifyTabDestroyed().

dom/workers/remoteworkers/RemoteWorkerManager.cpp

@@ -139,6 +139,8 @@ RemoteWorkerManager::LaunchInternal(RemoteWorkerController* aController,
     return;
   }
 
+  workerActor->Initialize();
+
   // This makes the link better the 2 actors.
   aController->SetWorkerActor(workerActor);
   workerActor->SetController(aController);

dom/workers/remoteworkers/RemoteWorkerParent.cpp

@@ -6,8 +6,10 @@
 
 #include "RemoteWorkerParent.h"
 #include "RemoteWorkerController.h"
+#include "mozilla/dom/ContentParent.h"
 #include "mozilla/ipc/BackgroundParent.h"
 #include "mozilla/Unused.h"
+#include "nsProxyRelease.h"
 
 namespace mozilla {
 
@@ -15,6 +17,35 @@ using namespace ipc;
 
 namespace dom {
 
+namespace {
+
+class UnregisterActorRunnable final : public Runnable
+{
+public:
+  explicit UnregisterActorRunnable(already_AddRefed<ContentParent> aParent)
+    : Runnable("UnregisterActorRunnable")
+    , mContentParent(aParent)
+  {
+    AssertIsOnBackgroundThread();
+  }
+
+  NS_IMETHOD
+  Run() override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    mContentParent->UnregisterRemoveWorkerActor();
+    mContentParent = nullptr;
+
+    return NS_OK;
+  }
+
+private:
+  RefPtr<ContentParent> mContentParent;
+};
+
+} // anonymous
+
 RemoteWorkerParent::RemoteWorkerParent()
 {
   AssertIsOnBackgroundThread();
@@ -27,12 +58,41 @@ RemoteWorkerParent::~RemoteWorkerParent()
   MOZ_ASSERT(XRE_IsParentProcess());
 }
 
+void
+RemoteWorkerParent::Initialize()
+{
+  RefPtr<ContentParent> parent = BackgroundParent::GetContentParent(Manager());
+
+  // Parent is null if the child actor runs on the parent process.
+  if (parent) {
+    parent->RegisterRemoteWorkerActor();
+
+    nsCOMPtr<nsIEventTarget> target =
+      SystemGroup::EventTargetFor(TaskCategory::Other);
+
+    NS_ProxyRelease("RemoteWorkerParent::Initialize ContentParent",
+                    target, parent.forget());
+  }
+}
+
 void
 RemoteWorkerParent::ActorDestroy(IProtocol::ActorDestroyReason)
 {
   AssertIsOnBackgroundThread();
   MOZ_ASSERT(XRE_IsParentProcess());
 
+  RefPtr<ContentParent> parent = BackgroundParent::GetContentParent(Manager());
+
+  // Parent is null if the child actor runs on the parent process.
+  if (parent) {
+    RefPtr<UnregisterActorRunnable> r =
+      new UnregisterActorRunnable(parent.forget());
+
+    nsCOMPtr<nsIEventTarget> target =
+      SystemGroup::EventTargetFor(TaskCategory::Other);
+    target->Dispatch(r.forget(), NS_DISPATCH_NORMAL);
+  }
+
   mController = nullptr;
 }
 

dom/workers/remoteworkers/RemoteWorkerParent.h

@@ -21,6 +21,9 @@ public:
 
   RemoteWorkerParent();
 
+  void
+  Initialize();
+
   void
   SetController(RemoteWorkerController* aController);