dom/ipc/ProcessPriorityManager.h@7e26c7da4463
dom/ipc/ProcessPriorityManager.h
Wed, 31 Dec 2014 06:55:50 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:55:50 +0100
- changeset 2
- 7e26c7da4463
- permissions
- -rw-r--r--
Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set sw=2 ts=8 et ft=cpp : */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
7 #ifndef mozilla_ProcessPriorityManager_h_
8 #define mozilla_ProcessPriorityManager_h_
10 #include "mozilla/HalTypes.h"
12 namespace mozilla {
13 namespace dom {
14 class ContentParent;
15 }
17 /**
18 * This class sets the priority of subprocesses in response to explicit
19 * requests and events in the system.
20 *
21 * A process's priority changes e.g. when it goes into the background via
22 * mozbrowser's setVisible(false). Process priority affects CPU scheduling and
23 * also which processes get killed when we run out of memory.
24 *
25 * After you call Initialize(), the only thing you probably have to do is call
26 * SetProcessPriority on processes immediately after creating them in order to
27 * set their initial priority. The ProcessPriorityManager takes care of the
28 * rest.
29 */
30 class ProcessPriorityManager MOZ_FINAL
31 {
32 public:
33 /**
34 * Initialize the ProcessPriorityManager machinery, causing the
35 * ProcessPriorityManager to actively manage the priorities of all
36 * subprocesses. You should call this before creating any subprocesses.
37 *
38 * You should also call this function even if you're in a child process,
39 * since it will initialize ProcessPriorityManagerChild.
40 */
41 static void Init();
43 /**
44 * Set the process priority of a given ContentParent's process.
45 *
46 * Note that because this method takes a ContentParent*, you can only set the
47 * priority of your subprocesses. In fact, because we don't support nested
48 * content processes (bug 761935), you can only call this method from the
49 * main process.
50 *
51 * It probably only makes sense to call this function immediately after a
52 * process is created. At this point, the process priority manager doesn't
53 * have enough context about the processs to know what its priority should
54 * be.
55 *
56 * Eventually whatever priority you set here can and probably will be
57 * overwritten by the process priority manager.
58 */
59 static void SetProcessPriority(dom::ContentParent* aContentParent,
60 hal::ProcessPriority aPriority);
62 /**
63 * Returns true iff this process's priority is FOREGROUND*.
64 *
65 * Note that because process priorities are set in the main process, it's
66 * possible for this method to return a stale value. So be careful about
67 * what you use this for.
68 */
69 static bool CurrentProcessIsForeground();
71 /**
72 * Returns true if one or more processes with FOREGROUND_HIGH priority are
73 * present, false otherwise.
74 */
75 static bool AnyProcessHasHighPriority();
77 /**
78 * Used to remove a ContentParent from background LRU pool when
79 * it is destroyed or its priority changed from BACKGROUND to others.
80 */
81 static void RemoveFromBackgroundLRUPool(dom::ContentParent* aContentParent);
83 /**
84 * Used to add a ContentParent into background LRU pool when
85 * its priority changed to BACKGROUND from others.
86 */
87 static void AddIntoBackgroundLRUPool(dom::ContentParent* aContentParent);
89 private:
90 ProcessPriorityManager();
91 DISALLOW_EVIL_CONSTRUCTORS(ProcessPriorityManager);
92 };
94 } // namespace mozilla
96 #endif
