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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_PreallocatedProcessManager_h
+#define mozilla_PreallocatedProcessManager_h
+
+#include "base/basictypes.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "nsStringFwd.h"
+
+namespace mozilla {
+namespace dom {
+class ContentParent;
+} // namespace dom
+
+/**
+ * This class manages a ContentParent that it starts up ahead of any particular
+ * need. You can then call Take() to get this process and use it. Since we
+ * already started it up, it should be ready for use faster than if you'd
+ * created the process when you needed it.
+ *
+ * This class watches the dom.ipc.processPrelaunch.enabled pref. If it changes
+ * from false to true, it preallocates a process. If it changes from true to
+ * false, it kills the preallocated process, if any.
+ *
+ * We don't expect this pref to flip between true and false in production, but
+ * flipping the pref is important for tests.
+ */
+class PreallocatedProcessManagerImpl;
+
+class PreallocatedProcessManager final {
+ typedef mozilla::dom::ContentParent ContentParent;
+
+ public:
+ static PreallocatedProcessManagerImpl* GetPPMImpl();
+
+ static bool Enabled();
+
+ /**
+ * Before first paint we don't want to allocate any processes in the
+ * background. To avoid that, the PreallocatedProcessManager won't start up
+ * any processes while there is a blocker active.
+ */
+ static void AddBlocker(const nsACString& aRemoteType, ContentParent* aParent);
+ static void RemoveBlocker(const nsACString& aRemoteType,
+ ContentParent* aParent);
+
+ /**
+ * Take a preallocated process, if we have one. If we don't have a
+ * preallocated process to return, this returns null.
+ *
+ * If we use a preallocated process, it will schedule the start of
+ * another on Idle (AllocateOnIdle()).
+ */
+ static already_AddRefed<ContentParent> Take(const nsACString& aRemoteType);
+
+ /**
+ * Note that a process was shut down, and should no longer be tracked as a
+ * preallocated process.
+ */
+ static void Erase(ContentParent* aParent);
+
+ private:
+ PreallocatedProcessManager();
+ DISALLOW_EVIL_CONSTRUCTORS(PreallocatedProcessManager);
+};
+
+} // namespace mozilla
+
+#endif // defined mozilla_PreallocatedProcessManager_h