1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/ipc/ProcessPriorityManager.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,96 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set sw=2 ts=8 et ft=cpp : */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.8 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef mozilla_ProcessPriorityManager_h_
1.11 +#define mozilla_ProcessPriorityManager_h_
1.12 +
1.13 +#include "mozilla/HalTypes.h"
1.14 +
1.15 +namespace mozilla {
1.16 +namespace dom {
1.17 +class ContentParent;
1.18 +}
1.19 +
1.20 +/**
1.21 + * This class sets the priority of subprocesses in response to explicit
1.22 + * requests and events in the system.
1.23 + *
1.24 + * A process's priority changes e.g. when it goes into the background via
1.25 + * mozbrowser's setVisible(false). Process priority affects CPU scheduling and
1.26 + * also which processes get killed when we run out of memory.
1.27 + *
1.28 + * After you call Initialize(), the only thing you probably have to do is call
1.29 + * SetProcessPriority on processes immediately after creating them in order to
1.30 + * set their initial priority. The ProcessPriorityManager takes care of the
1.31 + * rest.
1.32 + */
1.33 +class ProcessPriorityManager MOZ_FINAL
1.34 +{
1.35 +public:
1.36 + /**
1.37 + * Initialize the ProcessPriorityManager machinery, causing the
1.38 + * ProcessPriorityManager to actively manage the priorities of all
1.39 + * subprocesses. You should call this before creating any subprocesses.
1.40 + *
1.41 + * You should also call this function even if you're in a child process,
1.42 + * since it will initialize ProcessPriorityManagerChild.
1.43 + */
1.44 + static void Init();
1.45 +
1.46 + /**
1.47 + * Set the process priority of a given ContentParent's process.
1.48 + *
1.49 + * Note that because this method takes a ContentParent*, you can only set the
1.50 + * priority of your subprocesses. In fact, because we don't support nested
1.51 + * content processes (bug 761935), you can only call this method from the
1.52 + * main process.
1.53 + *
1.54 + * It probably only makes sense to call this function immediately after a
1.55 + * process is created. At this point, the process priority manager doesn't
1.56 + * have enough context about the processs to know what its priority should
1.57 + * be.
1.58 + *
1.59 + * Eventually whatever priority you set here can and probably will be
1.60 + * overwritten by the process priority manager.
1.61 + */
1.62 + static void SetProcessPriority(dom::ContentParent* aContentParent,
1.63 + hal::ProcessPriority aPriority);
1.64 +
1.65 + /**
1.66 + * Returns true iff this process's priority is FOREGROUND*.
1.67 + *
1.68 + * Note that because process priorities are set in the main process, it's
1.69 + * possible for this method to return a stale value. So be careful about
1.70 + * what you use this for.
1.71 + */
1.72 + static bool CurrentProcessIsForeground();
1.73 +
1.74 + /**
1.75 + * Returns true if one or more processes with FOREGROUND_HIGH priority are
1.76 + * present, false otherwise.
1.77 + */
1.78 + static bool AnyProcessHasHighPriority();
1.79 +
1.80 + /**
1.81 + * Used to remove a ContentParent from background LRU pool when
1.82 + * it is destroyed or its priority changed from BACKGROUND to others.
1.83 + */
1.84 + static void RemoveFromBackgroundLRUPool(dom::ContentParent* aContentParent);
1.85 +
1.86 + /**
1.87 + * Used to add a ContentParent into background LRU pool when
1.88 + * its priority changed to BACKGROUND from others.
1.89 + */
1.90 + static void AddIntoBackgroundLRUPool(dom::ContentParent* aContentParent);
1.91 +
1.92 +private:
1.93 + ProcessPriorityManager();
1.94 + DISALLOW_EVIL_CONSTRUCTORS(ProcessPriorityManager);
1.95 +};
1.96 +
1.97 +} // namespace mozilla
1.98 +
1.99 +#endif
