1 /* GIO - GLib Input, Output and Streaming Library
3 * Copyright (C) 2006-2007 Red Hat, Inc.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General
16 * Public License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
18 * Boston, MA 02111-1307, USA.
20 * Author: Alexander Larsson <alexl@redhat.com>
25 #include "gioscheduler.h"
26 #include "gcancellable.h"
30 * SECTION:gioscheduler
31 * @short_description: I/O Scheduler
34 * Schedules asynchronous I/O operations. #GIOScheduler integrates
35 * into the main event loop (#GMainLoop) and may use threads if they
38 * <para id="io-priority"><indexterm><primary>I/O priority</primary></indexterm>
39 * Each I/O operation has a priority, and the scheduler uses the priorities
40 * to determine the order in which operations are executed. They are
41 * <emphasis>not</emphasis> used to determine system-wide I/O scheduling.
42 * Priorities are integers, with lower numbers indicating higher priority.
43 * It is recommended to choose priorities between %G_PRIORITY_LOW and
44 * %G_PRIORITY_HIGH, with %G_PRIORITY_DEFAULT as a default.
48 struct _GIOSchedulerJob {
50 GIOSchedulerJobFunc job_func;
51 GSourceFunc cancel_func; /* Runs under job map lock */
53 GDestroyNotify destroy_notify;
54 GCancellable *cancellable;
55 GMainContext *context;
61 G_LOCK_DEFINE_STATIC(active_jobs);
62 static GSList *active_jobs = NULL;
64 static GThreadPool *job_thread_pool = NULL;
66 static void io_job_thread (gpointer data,
70 g_io_job_free (GIOSchedulerJob *job)
73 g_object_unref (job->cancellable);
75 g_main_context_unref (job->context);
80 g_io_job_compare (gconstpointer a,
84 const GIOSchedulerJob *aa = a;
85 const GIOSchedulerJob *bb = b;
87 /* Cancelled jobs are set prio == -1, so that
88 they are executed as quickly as possible */
90 /* Lower value => higher priority */
91 if (aa->io_priority < bb->io_priority)
93 if (aa->io_priority == bb->io_priority)
99 init_scheduler (gpointer arg)
101 if (job_thread_pool == NULL)
103 /* TODO: thread_pool_new can fail */
104 job_thread_pool = g_thread_pool_new (io_job_thread,
109 if (job_thread_pool != NULL)
111 g_thread_pool_set_sort_function (job_thread_pool,
114 /* It's kinda weird that this is a global setting
115 * instead of per threadpool. However, we really
116 * want to cache some threads, but not keep around
117 * those threads forever. */
118 g_thread_pool_set_max_idle_time (15 * 1000);
119 g_thread_pool_set_max_unused_threads (2);
126 remove_active_job (GIOSchedulerJob *job)
128 GIOSchedulerJob *other_job;
130 gboolean resort_jobs;
132 G_LOCK (active_jobs);
133 active_jobs = g_slist_delete_link (active_jobs, job->active_link);
136 for (l = active_jobs; l != NULL; l = l->next)
139 if (other_job->io_priority >= 0 &&
140 g_cancellable_is_cancelled (other_job->cancellable))
142 other_job->io_priority = -1;
146 G_UNLOCK (active_jobs);
149 job_thread_pool != NULL)
150 g_thread_pool_set_sort_function (job_thread_pool,
157 job_destroy (gpointer data)
159 GIOSchedulerJob *job = data;
161 if (job->destroy_notify)
162 job->destroy_notify (job->data);
164 remove_active_job (job);
169 io_job_thread (gpointer data,
172 GIOSchedulerJob *job = data;
175 if (job->cancellable)
176 g_cancellable_push_current (job->cancellable);
180 result = job->job_func (job, job->cancellable, job->data);
184 if (job->cancellable)
185 g_cancellable_pop_current (job->cancellable);
191 run_job_at_idle (gpointer data)
193 GIOSchedulerJob *job = data;
196 if (job->cancellable)
197 g_cancellable_push_current (job->cancellable);
199 result = job->job_func (job, job->cancellable, job->data);
201 if (job->cancellable)
202 g_cancellable_pop_current (job->cancellable);
208 * g_io_scheduler_push_job:
209 * @job_func: a #GIOSchedulerJobFunc.
210 * @user_data: data to pass to @job_func
211 * @notify: a #GDestroyNotify for @user_data, or %NULL
212 * @io_priority: the <link linkend="gioscheduler">I/O priority</link>
214 * @cancellable: optional #GCancellable object, %NULL to ignore.
216 * Schedules the I/O job to run.
218 * @notify will be called on @user_data after @job_func has returned,
219 * regardless whether the job was cancelled or has run to completion.
221 * If @cancellable is not %NULL, it can be used to cancel the I/O job
222 * by calling g_cancellable_cancel() or by calling
223 * g_io_scheduler_cancel_all_jobs().
226 g_io_scheduler_push_job (GIOSchedulerJobFunc job_func,
228 GDestroyNotify notify,
230 GCancellable *cancellable)
232 static GOnce once_init = G_ONCE_INIT;
233 GIOSchedulerJob *job;
235 g_return_if_fail (job_func != NULL);
237 job = g_new0 (GIOSchedulerJob, 1);
238 job->job_func = job_func;
239 job->data = user_data;
240 job->destroy_notify = notify;
241 job->io_priority = io_priority;
244 job->cancellable = g_object_ref (cancellable);
246 job->context = g_main_context_get_thread_default ();
248 g_main_context_ref (job->context);
250 G_LOCK (active_jobs);
251 active_jobs = g_slist_prepend (active_jobs, job);
252 job->active_link = active_jobs;
253 G_UNLOCK (active_jobs);
255 if (g_thread_supported())
257 g_once (&once_init, init_scheduler, NULL);
258 g_thread_pool_push (job_thread_pool, job, NULL);
262 /* Threads not available, instead do the i/o sync inside a
263 * low prio idle handler
265 job->idle_tag = g_idle_add_full (io_priority,
272 * g_io_scheduler_cancel_all_jobs:
274 * Cancels all cancellable I/O jobs.
276 * A job is cancellable if a #GCancellable was passed into
277 * g_io_scheduler_push_job().
280 g_io_scheduler_cancel_all_jobs (void)
282 GSList *cancellable_list, *l;
284 G_LOCK (active_jobs);
285 cancellable_list = NULL;
286 for (l = active_jobs; l != NULL; l = l->next)
288 GIOSchedulerJob *job = l->data;
289 if (job->cancellable)
290 cancellable_list = g_slist_prepend (cancellable_list,
291 g_object_ref (job->cancellable));
293 G_UNLOCK (active_jobs);
295 for (l = cancellable_list; l != NULL; l = l->next)
297 GCancellable *c = l->data;
298 g_cancellable_cancel (c);
301 g_slist_free (cancellable_list);
308 GDestroyNotify notify;
311 GCond *ack_condition;
315 mainloop_proxy_func (gpointer data)
317 MainLoopProxy *proxy = data;
319 proxy->ret_val = proxy->func (proxy->data);
322 proxy->notify (proxy->data);
326 g_mutex_lock (proxy->ack_lock);
327 g_cond_signal (proxy->ack_condition);
328 g_mutex_unlock (proxy->ack_lock);
335 mainloop_proxy_free (MainLoopProxy *proxy)
339 g_mutex_free (proxy->ack_lock);
340 g_cond_free (proxy->ack_condition);
347 * g_io_scheduler_job_send_to_mainloop:
348 * @job: a #GIOSchedulerJob
349 * @func: a #GSourceFunc callback that will be called in the original thread
350 * @user_data: data to pass to @func
351 * @notify: a #GDestroyNotify for @user_data, or %NULL
353 * Used from an I/O job to send a callback to be run in the thread
354 * that the job was started from, waiting for the result (and thus
355 * blocking the I/O job).
357 * Returns: The return value of @func
360 g_io_scheduler_job_send_to_mainloop (GIOSchedulerJob *job,
363 GDestroyNotify notify)
366 MainLoopProxy *proxy;
369 g_return_val_if_fail (job != NULL, FALSE);
370 g_return_val_if_fail (func != NULL, FALSE);
374 /* We just immediately re-enter in the case of idles (non-threads)
375 * Anything else would just deadlock. If you can't handle this, enable threads.
377 ret_val = func (user_data);
383 proxy = g_new0 (MainLoopProxy, 1);
385 proxy->data = user_data;
386 proxy->notify = notify;
387 proxy->ack_lock = g_mutex_new ();
388 proxy->ack_condition = g_cond_new ();
389 g_mutex_lock (proxy->ack_lock);
391 source = g_idle_source_new ();
392 g_source_set_priority (source, G_PRIORITY_DEFAULT);
393 g_source_set_callback (source, mainloop_proxy_func, proxy,
396 g_source_attach (source, job->context);
397 g_source_unref (source);
399 g_cond_wait (proxy->ack_condition, proxy->ack_lock);
400 g_mutex_unlock (proxy->ack_lock);
402 ret_val = proxy->ret_val;
403 mainloop_proxy_free (proxy);
409 * g_io_scheduler_job_send_to_mainloop_async:
410 * @job: a #GIOSchedulerJob
411 * @func: a #GSourceFunc callback that will be called in the original thread
412 * @user_data: data to pass to @func
413 * @notify: a #GDestroyNotify for @user_data, or %NULL
415 * Used from an I/O job to send a callback to be run asynchronously in
416 * the thread that the job was started from. The callback will be run
417 * when the main loop is available, but at that time the I/O job might
418 * have finished. The return value from the callback is ignored.
420 * Note that if you are passing the @user_data from g_io_scheduler_push_job()
421 * on to this function you have to ensure that it is not freed before
422 * @func is called, either by passing %NULL as @notify to
423 * g_io_scheduler_push_job() or by using refcounting for @user_data.
426 g_io_scheduler_job_send_to_mainloop_async (GIOSchedulerJob *job,
429 GDestroyNotify notify)
432 MainLoopProxy *proxy;
434 g_return_if_fail (job != NULL);
435 g_return_if_fail (func != NULL);
439 /* We just immediately re-enter in the case of idles (non-threads)
440 * Anything else would just deadlock. If you can't handle this, enable threads.
448 proxy = g_new0 (MainLoopProxy, 1);
450 proxy->data = user_data;
451 proxy->notify = notify;
453 source = g_idle_source_new ();
454 g_source_set_priority (source, G_PRIORITY_DEFAULT);
455 g_source_set_callback (source, mainloop_proxy_func, proxy,
456 (GDestroyNotify)mainloop_proxy_free);
458 g_source_attach (source, job->context);
459 g_source_unref (source);