88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_PreallocatedProcessManager_h
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#define mozilla_PreallocatedProcessManager_h
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#include "base/basictypes.h"
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#include "nsCOMPtr.h"
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#include "nsIObserver.h"
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namespace mozilla {
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namespace dom {
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class ContentParent;
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} // namespace dom
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/**
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* This class manages a ContentParent that it starts up ahead of any particular
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* need. You can then call Take() to get this process and use it. Since we
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* already started it up, it should be ready for use faster than if you'd
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* created the process when you needed it.
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*
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* This class watches the dom.ipc.processPrelaunch.enabled pref. If it changes
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* from false to true, it preallocates a process. If it changes from true to
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* false, it kills the preallocated process, if any.
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*
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* We don't expect this pref to flip between true and false in production, but
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* flipping the pref is important for tests.
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*
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* The static methods here are implemented by forwarding calls on to a
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* PreallocatedProcessManagerImpl singleton class, so if you add a new static
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* method here, you'll need to write a corresponding public method on the
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* singleton.
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*/
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class PreallocatedProcessManager final
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{
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typedef mozilla::dom::ContentParent ContentParent;
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public:
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/**
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* Create a process after a delay. We wait for a period of time (specified
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* by the dom.ipc.processPrelaunch.delayMs pref), then wait for this process
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* to go idle, then allocate the new process.
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*
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* If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
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* have a preallocated process, this function does nothing.
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*/
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static void AllocateAfterDelay();
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/**
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* Create a process once this process goes idle.
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*
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* If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
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* have a preallocated process, this function does nothing.
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*/
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static void AllocateOnIdle();
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/**
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* Create a process right now.
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*
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* If the dom.ipc.processPrelaunch.enabled pref is false, or if we already
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* have a preallocated process, this function does nothing.
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*/
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static void AllocateNow();
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/**
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* Take the preallocated process, if we have one. If we don't have one, this
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* returns null.
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*
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* If you call Take() twice in a row, the second call is guaranteed to return
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* null.
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*
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* After you Take() the preallocated process, you need to call one of the
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* Allocate* functions (or change the dom.ipc.processPrelaunch pref from
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* false to true) before we'll create a new process.
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*/
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static already_AddRefed<ContentParent> Take();
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private:
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PreallocatedProcessManager();
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DISALLOW_EVIL_CONSTRUCTORS(PreallocatedProcessManager);
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};
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} // namespace mozilla
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#endif // defined mozilla_PreallocatedProcessManager_h
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