1 files changed, 73 insertions, 0 deletions
diff --git a/dom/ipc/PreallocatedProcessManager.h b/dom/ipc/PreallocatedProcessManager.h
new file mode 100644
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+++ b/dom/ipc/PreallocatedProcessManager.h
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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