forked from mirrors/gecko-dev
81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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_ProcessPriorityManager_h_
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#define mozilla_ProcessPriorityManager_h_
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#include "mozilla/HalTypes.h"
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namespace mozilla {
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namespace dom {
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class ContentParent;
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class TabParent;
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} // namespace dom
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/**
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* This class sets the priority of subprocesses in response to explicit
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* requests and events in the system.
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*
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* A process's priority changes e.g. when it goes into the background via
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* mozbrowser's setVisible(false). Process priority affects CPU scheduling and
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* also which processes get killed when we run out of memory.
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*
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* After you call Initialize(), the only thing you probably have to do is call
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* SetProcessPriority on processes immediately after creating them in order to
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* set their initial priority. The ProcessPriorityManager takes care of the
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* rest.
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*/
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class ProcessPriorityManager final
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{
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public:
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/**
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* Initialize the ProcessPriorityManager machinery, causing the
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* ProcessPriorityManager to actively manage the priorities of all
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* subprocesses. You should call this before creating any subprocesses.
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*
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* You should also call this function even if you're in a child process,
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* since it will initialize ProcessPriorityManagerChild.
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*/
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static void Init();
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/**
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* Set the process priority of a given ContentParent's process.
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*
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* Note that because this method takes a ContentParent*, you can only set the
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* priority of your subprocesses. In fact, because we don't support nested
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* content processes (bug 761935), you can only call this method from the
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* main process.
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*
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* It probably only makes sense to call this function immediately after a
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* process is created. At this point, the process priority manager doesn't
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* have enough context about the processs to know what its priority should
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* be.
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*
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* Eventually whatever priority you set here can and probably will be
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* overwritten by the process priority manager.
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*/
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static void SetProcessPriority(dom::ContentParent* aContentParent,
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hal::ProcessPriority aPriority);
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/**
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* Returns true iff this process's priority is FOREGROUND*.
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*
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* Note that because process priorities are set in the main process, it's
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* possible for this method to return a stale value. So be careful about
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* what you use this for.
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*/
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static bool CurrentProcessIsForeground();
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static void TabActivityChanged(dom::TabParent* aTabParent, bool aIsActive);
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private:
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ProcessPriorityManager();
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DISALLOW_EVIL_CONSTRUCTORS(ProcessPriorityManager);
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};
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} // namespace mozilla
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#endif
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