[gnome-software/ramcq/ioprio: 27/28] lib: import ioprio code from tracker

[Richard Hughes <rhughes src gnome org>]

commit 325027698f8bad7ca1fbb9ae387eff2dc649702c
Author: Robert McQueen <rob endlessm com>
Date:   Fri Sep 7 14:11:45 2018 +0100

    lib: import ioprio code from tracker
    
    Unmodified import of
    https://gitlab.gnome.org/GNOME/tracker/blob/master/src/libtracker-common/tracker-ioprio.[ch]
    (at revision 162ae962), with namespace and header guards updated. This exports
    one function gs_ioprio_init which sets the calling thread to the idle IO
    scheduler class if possible, or best effort priority 7 (lowest) if not.

 lib/gs-ioprio.c | 150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/gs-ioprio.h |  32 ++++++++++++
 lib/meson.build |   2 +
 meson.build     |   2 +
 4 files changed, 186 insertions(+)
---
diff --git a/lib/gs-ioprio.c b/lib/gs-ioprio.c
new file mode 100644
index 00000000..f9b0349a
--- /dev/null
+++ b/lib/gs-ioprio.c
@@ -0,0 +1,150 @@
+/*
+ * Copyright (C) 2005, Novell, Inc.
+ * Copyright (C) 2006, Jamie McCracken <jamiemcc gnome org>
+ * Copyright (C) 2006, Anders Aagaard
+ *
+ * Based mostly on code by Robert Love <rml novell com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+
+#ifdef __linux__
+
+#include <stdio.h>
+#include <errno.h>
+
+#ifdef HAVE_LINUX_UNISTD_H
+#include <linux/unistd.h>
+#endif
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <glib/gstdio.h>
+
+#endif /* __linux__ */
+
+#include "gs-ioprio.h"
+
+/* We assume ALL linux architectures have the syscalls defined here */
+#ifdef __linux__
+
+/* Make sure the system call is supported */
+#ifndef __NR_ioprio_set
+
+#if defined(__i386__)
+#define __NR_ioprio_set                 289
+#define __NR_ioprio_get                 290
+#elif defined(__powerpc__) || defined(__powerpc64__)
+#define __NR_ioprio_set                 273
+#define __NR_ioprio_get                 274
+#elif defined(__x86_64__)
+#define __NR_ioprio_set                 251
+#define __NR_ioprio_get                 252
+#elif defined(__ia64__)
+#define __NR_ioprio_set                 1274
+#define __NR_ioprio_get                 1275
+#elif defined(__alpha__)
+#define __NR_ioprio_set                 442
+#define __NR_ioprio_get                 443
+#elif defined(__s390x__) || defined(__s390__)
+#define __NR_ioprio_set                 282
+#define __NR_ioprio_get                 283
+#elif defined(__SH4__)
+#define __NR_ioprio_set                 288
+#define __NR_ioprio_get                 289
+#elif defined(__SH5__)
+#define __NR_ioprio_set                 316
+#define __NR_ioprio_get                 317
+#elif defined(__sparc__) || defined(__sparc64__)
+#define __NR_ioprio_set                 196
+#define __NR_ioprio_get                 218
+#elif defined(__arm__)
+#define __NR_ioprio_set                 314
+#define __NR_ioprio_get                 315
+#else
+#error "Unsupported architecture!"
+#endif
+
+#endif /* __NR_ioprio_set */
+
+enum {
+       IOPRIO_CLASS_NONE,
+       IOPRIO_CLASS_RT,
+       IOPRIO_CLASS_BE,
+       IOPRIO_CLASS_IDLE,
+};
+
+enum {
+       IOPRIO_WHO_PROCESS = 1,
+       IOPRIO_WHO_PGRP,
+       IOPRIO_WHO_USER,
+};
+
+#define IOPRIO_CLASS_SHIFT 13
+
+static inline int
+ioprio_set (int which, int who, int ioprio_val)
+{
+       return syscall (__NR_ioprio_set, which, who, ioprio_val);
+}
+
+static int
+set_io_priority_idle (void)
+{
+       int ioprio, ioclass;
+
+       ioprio = 7; /* priority is ignored with idle class */
+       ioclass = IOPRIO_CLASS_IDLE << IOPRIO_CLASS_SHIFT;
+
+       return ioprio_set (IOPRIO_WHO_PROCESS, 0, ioprio | ioclass);
+}
+
+static int
+set_io_priority_best_effort (int ioprio_val)
+{
+       int ioclass;
+
+       ioclass = IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT;
+
+       return ioprio_set (IOPRIO_WHO_PROCESS, 0, ioprio_val | ioclass);
+}
+
+void
+gs_ioprio_init (void)
+{
+       if (set_io_priority_idle () == -1) {
+               g_message ("Could not set idle IO priority, attempting best effort of 7");
+
+               if (set_io_priority_best_effort (7) == -1) {
+                       g_message ("Could not set best effort IO priority either, giving up");
+               }
+       }
+}
+
+#else  /* __linux__ */
+
+void
+gs_ioprio_init (void)
+{
+}
+
+#endif /* __linux__ */
diff --git a/lib/gs-ioprio.h b/lib/gs-ioprio.h
new file mode 100644
index 00000000..e55b223e
--- /dev/null
+++ b/lib/gs-ioprio.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2006, Anders Aagaard
+ * Copyright (C) 2008, Nokia <ivan frade nokia com>
+ *
+ * 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, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ */
+
+#ifndef __GS_IOPRIO_H__
+#define __GS_IOPRIO_H__
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+void gs_ioprio_init (void);
+
+G_END_DECLS
+
+#endif /* __GS_IOPRIO_H__ */
diff --git a/lib/meson.build b/lib/meson.build
index bdd520f8..7b11e72c 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -77,6 +77,8 @@ libgnomesoftware = static_library(
     'gs-auth.c',
     'gs-category.c',
     'gs-debug.c',
+    'gs-ioprio.c',
+    'gs-ioprio.h',
     'gs-os-release.c',
     'gs-plugin.c',
     'gs-plugin-event.c',
diff --git a/meson.build b/meson.build
index c3add9d3..2035e1c7 100644
--- a/meson.build
+++ b/meson.build
@@ -92,6 +92,8 @@ add_global_link_arguments(
 # Needed for PATH_MAX and symlink()
 add_project_arguments('-D_XOPEN_SOURCE=700', language : 'c')
 
+conf.set('HAVE_LINUX_UNISTD_H', cc.has_header('linux/unistd.h'))
+
 appstream_glib = dependency('appstream-glib', version : '>= 0.7.11')
 gdk_pixbuf = dependency('gdk-pixbuf-2.0', version : '>= 2.32.0')
 gio_unix = dependency('gio-unix-2.0')