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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright 2019 Red Hat, Inc
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "glib.h"
#include "glibintl.h"
#include "gmemorymonitor.h"
#include "ginetaddress.h"
#include "ginetsocketaddress.h"
#include "ginitable.h"
#include "gioenumtypes.h"
#include "giomodule-priv.h"
#include "gtask.h"
/**
* SECTION:gmemorymonitor
* @title: GMemoryMonitor
* @short_description: Memory usage monitor
* @include: gio/gio.h
*
* #GMemoryMonitor will monitor system memory and suggest to the application
* when to free memory so as to leave more room for other applications.
* It is implemented on Linux using the [Low Memory Monitor](https://gitlab.freedesktop.org/hadess/low-memory-monitor/)
* ([API documentation](https://hadess.pages.freedesktop.org/low-memory-monitor/)).
*
* There is also an implementation for use inside Flatpak sandboxes.
*
* Possible actions to take when the signal is received are:
*
* - Free caches
* - Save files that haven't been looked at in a while to disk, ready to be reopened when needed
* - Run a garbage collection cycle
* - Try and compress fragmented allocations
* - Exit on idle if the process has no reason to stay around
* - Call [`malloc_trim(3)`](man:malloc_trim) to return cached heap pages to
* the kernel (if supported by your libc)
*
* Note that some actions may not always improve system performance, and so
* should be profiled for your application. `malloc_trim()`, for example, may
* make future heap allocations slower (due to releasing cached heap pages back
* to the kernel).
*
* See #GMemoryMonitorWarningLevel for details on the various warning levels.
*
* |[<!-- language="C" -->
* static void
* warning_cb (GMemoryMonitor *m, GMemoryMonitorWarningLevel level)
* {
* g_debug ("Warning level: %d", level);
* if (warning_level > G_MEMORY_MONITOR_WARNING_LEVEL_LOW)
* drop_caches ();
* }
*
* static GMemoryMonitor *
* monitor_low_memory (void)
* {
* GMemoryMonitor *m;
* m = g_memory_monitor_dup_default ();
* g_signal_connect (G_OBJECT (m), "low-memory-warning",
* G_CALLBACK (warning_cb), NULL);
* return m;
* }
* ]|
*
* Don't forget to disconnect the #GMemoryMonitor::low-memory-warning
* signal, and unref the #GMemoryMonitor itself when exiting.
*
* Since: 2.64
*/
/**
* GMemoryMonitor:
*
* #GMemoryMonitor monitors system memory and indicates when
* the system is low on memory.
*
* Since: 2.64
*/
/**
* GMemoryMonitorInterface:
* @g_iface: The parent interface.
* @low_memory_warning: the virtual function pointer for the
* #GMemoryMonitor::low-memory-warning signal.
*
* The virtual function table for #GMemoryMonitor.
*
* Since: 2.64
*/
G_DEFINE_INTERFACE_WITH_CODE (GMemoryMonitor, g_memory_monitor, G_TYPE_OBJECT,
g_type_interface_add_prerequisite (g_define_type_id, G_TYPE_INITABLE))
enum {
LOW_MEMORY_WARNING,
LAST_SIGNAL
};
static guint signals[LAST_SIGNAL] = { 0 };
/**
* g_memory_monitor_dup_default:
*
* Gets a reference to the default #GMemoryMonitor for the system.
*
* Returns: (not nullable) (transfer full): a new reference to the default #GMemoryMonitor
*
* Since: 2.64
*/
GMemoryMonitor *
g_memory_monitor_dup_default (void)
{
return g_object_ref (_g_io_module_get_default (G_MEMORY_MONITOR_EXTENSION_POINT_NAME,
"GIO_USE_MEMORY_MONITOR",
NULL));
}
static void
g_memory_monitor_default_init (GMemoryMonitorInterface *iface)
{
/**
* GMemoryMonitor::low-memory-warning:
* @monitor: a #GMemoryMonitor
* @level: the #GMemoryMonitorWarningLevel warning level
*
* Emitted when the system is running low on free memory. The signal
* handler should then take the appropriate action depending on the
* warning level. See the #GMemoryMonitorWarningLevel documentation for
* details.
*
* Since: 2.64
*/
signals[LOW_MEMORY_WARNING] =
g_signal_new (I_("low-memory-warning"),
G_TYPE_MEMORY_MONITOR,
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GMemoryMonitorInterface, low_memory_warning),
NULL, NULL,
NULL,
G_TYPE_NONE, 1,
G_TYPE_MEMORY_MONITOR_WARNING_LEVEL);
}
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