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	Depends on D155254 Differential Revision: https://phabricator.services.mozilla.com/D170397
		
			
				
	
	
		
			93 lines
		
	
	
	
		
			3.3 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			93 lines
		
	
	
	
		
			3.3 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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class nsFrameLoader;
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namespace mozilla {
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namespace dom {
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class BrowserParent;
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class CanonicalBrowsingContext;
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class ContentParent;
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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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 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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  /**
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   * Updates the contents of mHighPriorityBrowserParents to keep track of
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   * the list of TabIds for this process that are high priority.
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   */
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  static void BrowserPriorityChanged(dom::CanonicalBrowsingContext* aBC,
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                                     bool aPriority);
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  static void BrowserPriorityChanged(dom::BrowserParent* aBrowserParent,
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                                     bool aPriority);
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 private:
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  ProcessPriorityManager();
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  ProcessPriorityManager(const ProcessPriorityManager&) = delete;
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  const ProcessPriorityManager& operator=(const ProcessPriorityManager&) =
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      delete;
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};
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}  // namespace mozilla
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#endif
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