gio: gmemorymonitorbase: parent class of GMemoryMonitor backends

This class provides the shared functions, such as sending a signal and
string and value conversion. The backend classes should inherit this
class to get the shared functions.

It adds a configure time check for `sysinfo()`, as some systems don’t
have it.

gio/gmemorymonitorbase.c

@@ -0,0 +1,153 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2025 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 "gcancellable.h"
+#include "ginitable.h"
+#include "gioerror.h"
+#include "giomodule-priv.h"
+#include "glib/gstdio.h"
+#include "glibintl.h"
+#include "gmemorymonitor.h"
+#include "gmemorymonitorbase.h"
+
+#ifdef HAVE_SYSINFO
+#include <sys/sysinfo.h>
+#endif
+
+/**
+ * GMemoryMonitorBase:
+ *
+ * An abstract base class for implementations of [iface@Gio.MemoryMonitor] which
+ * provides several defined warning levels (`GLowMemoryLevel`) and tracks how
+ * often they are notified to the user via [signal@Gio.MemoryMonitor::low-memory-warning]
+ * to limit the number of signal emissions to one every 15 seconds for each level.
+ * [method@Gio.MemoryMonitorBase.send_event_to_user] is provided for this purpose.
+ */
+
+/* The interval between sending a signal in second */
+#define RECOVERY_INTERVAL_SEC 15
+
+#define G_MEMORY_MONITOR_BASE_GET_INITABLE_IFACE(o) (G_TYPE_INSTANCE_GET_INTERFACE ((o), G_TYPE_INITABLE, GInitable))
+
+static void g_memory_monitor_base_iface_init (GMemoryMonitorInterface *iface);
+static void g_memory_monitor_base_initable_iface_init (GInitableIface *iface);
+
+typedef struct
+{
+  GObject parent_instance;
+
+  guint64 last_trigger_us[G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_COUNT];
+} GMemoryMonitorBasePrivate;
+
+
+G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GMemoryMonitorBase, g_memory_monitor_base, G_TYPE_OBJECT,
+                                  G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
+                                    g_memory_monitor_base_initable_iface_init)
+                                  G_IMPLEMENT_INTERFACE (G_TYPE_MEMORY_MONITOR,
+                                      g_memory_monitor_base_iface_init)
+                                  G_ADD_PRIVATE (GMemoryMonitorBase))
+
+gdouble
+g_memory_monitor_base_query_mem_ratio (void)
+{
+#ifdef HAVE_SYSINFO
+  struct sysinfo info;
+
+  if (sysinfo (&info))
+    return -1.0;
+
+  if (info.totalram == 0)
+    return -1.0;
+
+  return (gdouble) ((gdouble) info.freeram / (gdouble) info.totalram);
+#else
+  return -1.0;
+#endif
+}
+
+GMemoryMonitorWarningLevel
+g_memory_monitor_base_level_enum_to_byte (GMemoryMonitorLowMemoryLevel level)
+{
+  const GMemoryMonitorWarningLevel level_bytes[G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_COUNT] = {
+    [G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_LOW] = 50,
+    [G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_MEDIUM] = 100,
+    [G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_CRITICAL] = 255
+  };
+
+  if ((int) level < G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_INVALID ||
+      (int) level >= G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_COUNT)
+    g_assert_not_reached ();
+
+  if (level == G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_INVALID)
+    return 0;
+
+  return level_bytes[level];
+}
+
+void
+g_memory_monitor_base_send_event_to_user (GMemoryMonitorBase              *monitor,
+                                          GMemoryMonitorLowMemoryLevel     warning_level)
+{
+  gint64 current_time;
+  GMemoryMonitorBasePrivate *priv = g_memory_monitor_base_get_instance_private (monitor);
+
+  current_time = g_get_monotonic_time ();
+
+  if (priv->last_trigger_us[warning_level] == 0 ||
+      (current_time - priv->last_trigger_us[warning_level]) > (RECOVERY_INTERVAL_SEC * G_USEC_PER_SEC))
+    {
+      g_debug ("Send low memory signal with warning level %u", warning_level);
+
+      g_signal_emit_by_name (monitor, "low-memory-warning",
+                             g_memory_monitor_base_level_enum_to_byte (warning_level));
+      priv->last_trigger_us[warning_level] = current_time;
+    }
+}
+
+static gboolean
+g_memory_monitor_base_initable_init (GInitable     *initable,
+                                        GCancellable  *cancellable,
+                                        GError       **error)
+{
+  return TRUE;
+}
+
+static void
+g_memory_monitor_base_init (GMemoryMonitorBase *monitor)
+{
+}
+
+static void
+g_memory_monitor_base_class_init (GMemoryMonitorBaseClass *klass)
+{
+}
+
+static void
+g_memory_monitor_base_iface_init (GMemoryMonitorInterface *monitor_iface)
+{
+}
+
+static void
+g_memory_monitor_base_initable_iface_init (GInitableIface *iface)
+{
+  iface->init = g_memory_monitor_base_initable_init;
+}

gio/gmemorymonitorbase.h

@@ -0,0 +1,53 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2025 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/>.
+ */
+
+#ifndef __G_MEMORY_MONITOR_BASE_H__
+#define __G_MEMORY_MONITOR_BASE_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+#define G_TYPE_MEMORY_MONITOR_BASE         (g_memory_monitor_base_get_type ())
+
+G_DECLARE_DERIVABLE_TYPE (GMemoryMonitorBase, g_memory_monitor_base, G, MEMORY_MONITOR_BASE, GObject)
+
+typedef enum
+{
+  G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_INVALID = -1,
+  G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_LOW = 0,
+  G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_MEDIUM,
+  G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_CRITICAL,
+  G_MEMORY_MONITOR_LOW_MEMORY_LEVEL_COUNT
+} GMemoryMonitorLowMemoryLevel;
+
+struct _GMemoryMonitorBaseClass
+{
+  GObjectClass parent_class;
+};
+
+void                        g_memory_monitor_base_send_event_to_user (GMemoryMonitorBase              *monitor,
+                                                                      GMemoryMonitorLowMemoryLevel     warning_level);
+GMemoryMonitorWarningLevel  g_memory_monitor_base_level_enum_to_byte (GMemoryMonitorLowMemoryLevel     level);
+gdouble                     g_memory_monitor_base_query_mem_ratio    (void);
+
+G_END_DECLS
+
+#endif /* __G_MEMORY_MONITOR_BASE_H__ */

gio/meson.build

@@ -528,6 +528,7 @@ gio_base_sources = files(
   'gmarshal-internal.c',
   'gmount.c',
   'gmemorymonitor.c',
+  'gmemorymonitorbase.c',
   'gmemorymonitordbus.c',
   'gmemoryinputstream.c',
   'gmemoryoutputstream.c',

meson.build

@@ -759,6 +759,7 @@ functions = [
   'strtoll_l',
   'strtoull_l',
   'symlink',
+  'sysinfo',
   'timegm',
   'unsetenv',
   'uselocale',