/src/pango/subprojects/glib/gio/gmemorymonitor.c
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1 | | /* GIO - GLib Input, Output and Streaming Library |
2 | | * |
3 | | * Copyright 2019 Red Hat, Inc |
4 | | * |
5 | | * SPDX-License-Identifier: LGPL-2.1-or-later |
6 | | * |
7 | | * This library is free software; you can redistribute it and/or |
8 | | * modify it under the terms of the GNU Lesser General Public |
9 | | * License as published by the Free Software Foundation; either |
10 | | * version 2.1 of the License, or (at your option) any later version. |
11 | | * |
12 | | * This library is distributed in the hope that it will be useful, |
13 | | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
15 | | * Lesser General Public License for more details. |
16 | | * |
17 | | * You should have received a copy of the GNU Lesser General |
18 | | * Public License along with this library; if not, see <http://www.gnu.org/licenses/>. |
19 | | */ |
20 | | |
21 | | #include "config.h" |
22 | | #include "glib.h" |
23 | | #include "glibintl.h" |
24 | | |
25 | | #include "gmemorymonitor.h" |
26 | | #include "ginetaddress.h" |
27 | | #include "ginetsocketaddress.h" |
28 | | #include "ginitable.h" |
29 | | #include "gioenumtypes.h" |
30 | | #include "giomodule-priv.h" |
31 | | #include "gtask.h" |
32 | | |
33 | | /** |
34 | | * GMemoryMonitor: |
35 | | * |
36 | | * `GMemoryMonitor` will monitor system memory and suggest to the application |
37 | | * when to free memory so as to leave more room for other applications. |
38 | | * It is implemented on Linux using the |
39 | | * [Low Memory Monitor](https://gitlab.freedesktop.org/hadess/low-memory-monitor/) |
40 | | * ([API documentation](https://hadess.pages.freedesktop.org/low-memory-monitor/)). |
41 | | * |
42 | | * There is also an implementation for use inside Flatpak sandboxes. |
43 | | * |
44 | | * Possible actions to take when the signal is received are: |
45 | | * |
46 | | * - Free caches |
47 | | * - Save files that haven’t been looked at in a while to disk, ready to be reopened when needed |
48 | | * - Run a garbage collection cycle |
49 | | * - Try and compress fragmented allocations |
50 | | * - Exit on idle if the process has no reason to stay around |
51 | | * - Call [`malloc_trim(3)`](man:malloc_trim(3)) to return cached heap pages to |
52 | | * the kernel (if supported by your libc) |
53 | | * |
54 | | * Note that some actions may not always improve system performance, and so |
55 | | * should be profiled for your application. `malloc_trim()`, for example, may |
56 | | * make future heap allocations slower (due to releasing cached heap pages back |
57 | | * to the kernel). |
58 | | * |
59 | | * See [type@Gio.MemoryMonitorWarningLevel] for details on the various warning |
60 | | * levels. |
61 | | * |
62 | | * ```c |
63 | | * static void |
64 | | * warning_cb (GMemoryMonitor *m, GMemoryMonitorWarningLevel level) |
65 | | * { |
66 | | * g_debug ("Warning level: %d", level); |
67 | | * if (warning_level > G_MEMORY_MONITOR_WARNING_LEVEL_LOW) |
68 | | * drop_caches (); |
69 | | * } |
70 | | * |
71 | | * static GMemoryMonitor * |
72 | | * monitor_low_memory (void) |
73 | | * { |
74 | | * GMemoryMonitor *m; |
75 | | * m = g_memory_monitor_dup_default (); |
76 | | * g_signal_connect (G_OBJECT (m), "low-memory-warning", |
77 | | * G_CALLBACK (warning_cb), NULL); |
78 | | * return m; |
79 | | * } |
80 | | * ``` |
81 | | * |
82 | | * Don’t forget to disconnect the [signal@Gio.MemoryMonitor::low-memory-warning] |
83 | | * signal, and unref the `GMemoryMonitor` itself when exiting. |
84 | | * |
85 | | * Since: 2.64 |
86 | | */ |
87 | | |
88 | | /** |
89 | | * GMemoryMonitorInterface: |
90 | | * @g_iface: The parent interface. |
91 | | * @low_memory_warning: the virtual function pointer for the |
92 | | * #GMemoryMonitor::low-memory-warning signal. |
93 | | * |
94 | | * The virtual function table for #GMemoryMonitor. |
95 | | * |
96 | | * Since: 2.64 |
97 | | */ |
98 | | |
99 | | G_DEFINE_INTERFACE_WITH_CODE (GMemoryMonitor, g_memory_monitor, G_TYPE_OBJECT, |
100 | | g_type_interface_add_prerequisite (g_define_type_id, G_TYPE_INITABLE)) |
101 | | |
102 | | enum { |
103 | | LOW_MEMORY_WARNING, |
104 | | LAST_SIGNAL |
105 | | }; |
106 | | |
107 | | static guint signals[LAST_SIGNAL] = { 0 }; |
108 | | |
109 | | /** |
110 | | * g_memory_monitor_dup_default: |
111 | | * |
112 | | * Gets a reference to the default #GMemoryMonitor for the system. |
113 | | * |
114 | | * Returns: (not nullable) (transfer full): a new reference to the default #GMemoryMonitor |
115 | | * |
116 | | * Since: 2.64 |
117 | | */ |
118 | | GMemoryMonitor * |
119 | | g_memory_monitor_dup_default (void) |
120 | 0 | { |
121 | 0 | return g_object_ref (_g_io_module_get_default (G_MEMORY_MONITOR_EXTENSION_POINT_NAME, |
122 | 0 | "GIO_USE_MEMORY_MONITOR", |
123 | 0 | NULL)); |
124 | 0 | } |
125 | | |
126 | | static void |
127 | | g_memory_monitor_default_init (GMemoryMonitorInterface *iface) |
128 | 0 | { |
129 | | /** |
130 | | * GMemoryMonitor::low-memory-warning: |
131 | | * @monitor: a #GMemoryMonitor |
132 | | * @level: the #GMemoryMonitorWarningLevel warning level |
133 | | * |
134 | | * Emitted when the system is running low on free memory. The signal |
135 | | * handler should then take the appropriate action depending on the |
136 | | * warning level. See the #GMemoryMonitorWarningLevel documentation for |
137 | | * details. |
138 | | * |
139 | | * Since: 2.64 |
140 | | */ |
141 | 0 | signals[LOW_MEMORY_WARNING] = |
142 | 0 | g_signal_new (I_("low-memory-warning"), |
143 | 0 | G_TYPE_MEMORY_MONITOR, |
144 | 0 | G_SIGNAL_RUN_LAST, |
145 | 0 | G_STRUCT_OFFSET (GMemoryMonitorInterface, low_memory_warning), |
146 | 0 | NULL, NULL, |
147 | 0 | NULL, |
148 | 0 | G_TYPE_NONE, 1, |
149 | 0 | G_TYPE_MEMORY_MONITOR_WARNING_LEVEL); |
150 | 0 | } |