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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 : 365 : 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 : 1 : g_memory_monitor_dup_default (void)
120 : : {
121 : 1 : return g_object_ref (_g_io_module_get_default (G_MEMORY_MONITOR_EXTENSION_POINT_NAME,
122 : : "GIO_USE_MEMORY_MONITOR",
123 : : NULL));
124 : : }
125 : :
126 : : static void
127 : 2 : g_memory_monitor_default_init (GMemoryMonitorInterface *iface)
128 : : {
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 : 2 : signals[LOW_MEMORY_WARNING] =
142 : 2 : g_signal_new (I_("low-memory-warning"),
143 : : G_TYPE_MEMORY_MONITOR,
144 : : G_SIGNAL_RUN_LAST,
145 : : G_STRUCT_OFFSET (GMemoryMonitorInterface, low_memory_warning),
146 : : NULL, NULL,
147 : : NULL,
148 : : G_TYPE_NONE, 1,
149 : : G_TYPE_MEMORY_MONITOR_WARNING_LEVEL);
150 : 2 : }
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