/* GIO - GLib Input, Output and Streaming Library * * Copyright (C) 2006-2007 Red Hat, Inc. * * 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 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., 59 Temple Place, Suite 330, * Boston, MA 02111-1307, USA. * * Author: Alexander Larsson */ #include "config.h" #include "gioscheduler.h" #include "gcancellable.h" /** * SECTION:gioscheduler * @short_description: I/O Scheduler * @include: gio/gio.h * * Schedules asynchronous I/O operations. #GIOScheduler integrates * into the main event loop (#GMainLoop) and uses threads. * * I/O priority * Each I/O operation has a priority, and the scheduler uses the priorities * to determine the order in which operations are executed. They are * not used to determine system-wide I/O scheduling. * Priorities are integers, with lower numbers indicating higher priority. * It is recommended to choose priorities between %G_PRIORITY_LOW and * %G_PRIORITY_HIGH, with %G_PRIORITY_DEFAULT as a default. * **/ struct _GIOSchedulerJob { GSList *active_link; GIOSchedulerJobFunc job_func; GSourceFunc cancel_func; /* Runs under job map lock */ gpointer data; GDestroyNotify destroy_notify; gint io_priority; GCancellable *cancellable; GMainContext *context; }; G_LOCK_DEFINE_STATIC(active_jobs); static GSList *active_jobs = NULL; static GThreadPool *job_thread_pool = NULL; static void io_job_thread (gpointer data, gpointer user_data); static void g_io_job_free (GIOSchedulerJob *job) { if (job->cancellable) g_object_unref (job->cancellable); g_main_context_unref (job->context); g_free (job); } static gint g_io_job_compare (gconstpointer a, gconstpointer b, gpointer user_data) { const GIOSchedulerJob *aa = a; const GIOSchedulerJob *bb = b; /* Cancelled jobs are set prio == -1, so that they are executed as quickly as possible */ /* Lower value => higher priority */ if (aa->io_priority < bb->io_priority) return -1; if (aa->io_priority == bb->io_priority) return 0; return 1; } static gpointer init_scheduler (gpointer arg) { if (job_thread_pool == NULL) { /* TODO: thread_pool_new can fail */ job_thread_pool = g_thread_pool_new (io_job_thread, NULL, 10, FALSE, NULL); if (job_thread_pool != NULL) { g_thread_pool_set_sort_function (job_thread_pool, g_io_job_compare, NULL); /* It's kinda weird that this is a global setting * instead of per threadpool. However, we really * want to cache some threads, but not keep around * those threads forever. */ g_thread_pool_set_max_idle_time (15 * 1000); g_thread_pool_set_max_unused_threads (2); } } return NULL; } static void remove_active_job (GIOSchedulerJob *job) { GIOSchedulerJob *other_job; GSList *l; gboolean resort_jobs; G_LOCK (active_jobs); active_jobs = g_slist_delete_link (active_jobs, job->active_link); resort_jobs = FALSE; for (l = active_jobs; l != NULL; l = l->next) { other_job = l->data; if (other_job->io_priority >= 0 && g_cancellable_is_cancelled (other_job->cancellable)) { other_job->io_priority = -1; resort_jobs = TRUE; } } G_UNLOCK (active_jobs); if (resort_jobs && job_thread_pool != NULL) g_thread_pool_set_sort_function (job_thread_pool, g_io_job_compare, NULL); } static void job_destroy (gpointer data) { GIOSchedulerJob *job = data; if (job->destroy_notify) job->destroy_notify (job->data); remove_active_job (job); g_io_job_free (job); } static void io_job_thread (gpointer data, gpointer user_data) { GIOSchedulerJob *job = data; gboolean result; if (job->cancellable) g_cancellable_push_current (job->cancellable); do { result = job->job_func (job, job->cancellable, job->data); } while (result); if (job->cancellable) g_cancellable_pop_current (job->cancellable); job_destroy (job); } /** * g_io_scheduler_push_job: * @job_func: a #GIOSchedulerJobFunc. * @user_data: data to pass to @job_func * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL * @io_priority: the I/O priority * of the request. * @cancellable: optional #GCancellable object, %NULL to ignore. * * Schedules the I/O job to run in another thread. * * @notify will be called on @user_data after @job_func has returned, * regardless whether the job was cancelled or has run to completion. * * If @cancellable is not %NULL, it can be used to cancel the I/O job * by calling g_cancellable_cancel() or by calling * g_io_scheduler_cancel_all_jobs(). **/ void g_io_scheduler_push_job (GIOSchedulerJobFunc job_func, gpointer user_data, GDestroyNotify notify, gint io_priority, GCancellable *cancellable) { static GOnce once_init = G_ONCE_INIT; GIOSchedulerJob *job; g_return_if_fail (job_func != NULL); job = g_new0 (GIOSchedulerJob, 1); job->job_func = job_func; job->data = user_data; job->destroy_notify = notify; job->io_priority = io_priority; if (cancellable) job->cancellable = g_object_ref (cancellable); job->context = g_main_context_ref_thread_default (); G_LOCK (active_jobs); active_jobs = g_slist_prepend (active_jobs, job); job->active_link = active_jobs; G_UNLOCK (active_jobs); g_once (&once_init, init_scheduler, NULL); g_thread_pool_push (job_thread_pool, job, NULL); } /** * g_io_scheduler_cancel_all_jobs: * * Cancels all cancellable I/O jobs. * * A job is cancellable if a #GCancellable was passed into * g_io_scheduler_push_job(). **/ void g_io_scheduler_cancel_all_jobs (void) { GSList *cancellable_list, *l; G_LOCK (active_jobs); cancellable_list = NULL; for (l = active_jobs; l != NULL; l = l->next) { GIOSchedulerJob *job = l->data; if (job->cancellable) cancellable_list = g_slist_prepend (cancellable_list, g_object_ref (job->cancellable)); } G_UNLOCK (active_jobs); for (l = cancellable_list; l != NULL; l = l->next) { GCancellable *c = l->data; g_cancellable_cancel (c); g_object_unref (c); } g_slist_free (cancellable_list); } typedef struct { GSourceFunc func; gboolean ret_val; gpointer data; GDestroyNotify notify; GMutex ack_lock; GCond ack_condition; gboolean ack; } MainLoopProxy; static gboolean mainloop_proxy_func (gpointer data) { MainLoopProxy *proxy = data; proxy->ret_val = proxy->func (proxy->data); if (proxy->notify) proxy->notify (proxy->data); g_mutex_lock (&proxy->ack_lock); proxy->ack = TRUE; g_cond_signal (&proxy->ack_condition); g_mutex_unlock (&proxy->ack_lock); return FALSE; } static void mainloop_proxy_free (MainLoopProxy *proxy) { g_mutex_clear (&proxy->ack_lock); g_cond_clear (&proxy->ack_condition); g_free (proxy); } /** * g_io_scheduler_job_send_to_mainloop: * @job: a #GIOSchedulerJob * @func: a #GSourceFunc callback that will be called in the original thread * @user_data: data to pass to @func * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL * * Used from an I/O job to send a callback to be run in the thread * that the job was started from, waiting for the result (and thus * blocking the I/O job). * * Returns: The return value of @func **/ gboolean g_io_scheduler_job_send_to_mainloop (GIOSchedulerJob *job, GSourceFunc func, gpointer user_data, GDestroyNotify notify) { GSource *source; MainLoopProxy *proxy; gboolean ret_val; g_return_val_if_fail (job != NULL, FALSE); g_return_val_if_fail (func != NULL, FALSE); proxy = g_new0 (MainLoopProxy, 1); proxy->func = func; proxy->data = user_data; proxy->notify = notify; g_mutex_init (&proxy->ack_lock); g_cond_init (&proxy->ack_condition); g_mutex_lock (&proxy->ack_lock); source = g_idle_source_new (); g_source_set_priority (source, G_PRIORITY_DEFAULT); g_source_set_callback (source, mainloop_proxy_func, proxy, NULL); g_source_attach (source, job->context); g_source_unref (source); while (!proxy->ack) g_cond_wait (&proxy->ack_condition, &proxy->ack_lock); g_mutex_unlock (&proxy->ack_lock); ret_val = proxy->ret_val; mainloop_proxy_free (proxy); return ret_val; } /** * g_io_scheduler_job_send_to_mainloop_async: * @job: a #GIOSchedulerJob * @func: a #GSourceFunc callback that will be called in the original thread * @user_data: data to pass to @func * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL * * Used from an I/O job to send a callback to be run asynchronously in * the thread that the job was started from. The callback will be run * when the main loop is available, but at that time the I/O job might * have finished. The return value from the callback is ignored. * * Note that if you are passing the @user_data from g_io_scheduler_push_job() * on to this function you have to ensure that it is not freed before * @func is called, either by passing %NULL as @notify to * g_io_scheduler_push_job() or by using refcounting for @user_data. **/ void g_io_scheduler_job_send_to_mainloop_async (GIOSchedulerJob *job, GSourceFunc func, gpointer user_data, GDestroyNotify notify) { GSource *source; MainLoopProxy *proxy; g_return_if_fail (job != NULL); g_return_if_fail (func != NULL); proxy = g_new0 (MainLoopProxy, 1); proxy->func = func; proxy->data = user_data; proxy->notify = notify; g_mutex_init (&proxy->ack_lock); g_cond_init (&proxy->ack_condition); source = g_idle_source_new (); g_source_set_priority (source, G_PRIORITY_DEFAULT); g_source_set_callback (source, mainloop_proxy_func, proxy, (GDestroyNotify)mainloop_proxy_free); g_source_attach (source, job->context); g_source_unref (source); }