io/task.c

   1 /*
   2  * QEMU I/O task
   3  *
   4  * Copyright (c) 2015 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "io/task.h"
  23 #include "qapi/error.h"
  24 #include "qemu/thread.h"
  25 #include "trace.h"
  26
  27 struct QIOTask {
  28     Object *source;
  29     QIOTaskFunc func;
  30     gpointer opaque;
  31     GDestroyNotify destroy;
  32     Error *err;
  33     gpointer result;
  34     GDestroyNotify destroyResult;
  35 };
  36
  37
  38 QIOTask *qio_task_new(Object *source,
  39                       QIOTaskFunc func,
  40                       gpointer opaque,
  41                       GDestroyNotify destroy)
  42 {
  43     QIOTask *task;
  44
  45     task = g_new0(QIOTask, 1);
  46
  47     task->source = source;
  48     object_ref(source);
  49     task->func = func;
  50     task->opaque = opaque;
  51     task->destroy = destroy;
  52
  53     trace_qio_task_new(task, source, func, opaque);
  54
  55     return task;
  56 }
  57
  58 static void qio_task_free(QIOTask *task)
  59 {
  60     if (task->destroy) {
  61         task->destroy(task->opaque);
  62     }
  63     if (task->destroyResult) {
  64         task->destroyResult(task->result);
  65     }
  66     if (task->err) {
  67         error_free(task->err);
  68     }
  69     object_unref(task->source);
  70
  71     g_free(task);
  72 }
  73
  74
  75 struct QIOTaskThreadData {
  76     QIOTask *task;
  77     QIOTaskWorker worker;
  78     gpointer opaque;
  79     GDestroyNotify destroy;
  80     GMainContext *context;
  81 };
  82
  83
  84 static gboolean qio_task_thread_result(gpointer opaque)
  85 {
  86     struct QIOTaskThreadData *data = opaque;
  87
  88     trace_qio_task_thread_result(data->task);
  89     qio_task_complete(data->task);
  90
  91     if (data->destroy) {
  92         data->destroy(data->opaque);
  93     }
  94
  95     if (data->context) {
  96         g_main_context_unref(data->context);
  97     }
  98
  99     g_free(data);
 100
 101     return FALSE;
 102 }
 103
 104
 105 static gpointer qio_task_thread_worker(gpointer opaque)
 106 {
 107     struct QIOTaskThreadData *data = opaque;
 108     GSource *idle;
 109
 110     trace_qio_task_thread_run(data->task);
 111     data->worker(data->task, data->opaque);
 112
 113     /* We're running in the background thread, and must only
 114      * ever report the task results in the main event loop
 115      * thread. So we schedule an idle callback to report
 116      * the worker results
 117      */
 118     trace_qio_task_thread_exit(data->task);
 119
 120     idle = g_idle_source_new();
 121     g_source_set_callback(idle, qio_task_thread_result, data, NULL);
 122     g_source_attach(idle, data->context);
 123
 124     return NULL;
 125 }
 126
 127
 128 void qio_task_run_in_thread(QIOTask *task,
 129                             QIOTaskWorker worker,
 130                             gpointer opaque,
 131                             GDestroyNotify destroy,
 132                             GMainContext *context)
 133 {
 134     struct QIOTaskThreadData *data = g_new0(struct QIOTaskThreadData, 1);
 135     QemuThread thread;
 136
 137     if (context) {
 138         g_main_context_ref(context);
 139     }
 140
 141     data->task = task;
 142     data->worker = worker;
 143     data->opaque = opaque;
 144     data->destroy = destroy;
 145     data->context = context;
 146
 147     trace_qio_task_thread_start(task, worker, opaque);
 148     qemu_thread_create(&thread,
 149                        "io-task-worker",
 150                        qio_task_thread_worker,
 151                        data,
 152                        QEMU_THREAD_DETACHED);
 153 }
 154
 155
 156 void qio_task_complete(QIOTask *task)
 157 {
 158     task->func(task, task->opaque);
 159     trace_qio_task_complete(task);
 160     qio_task_free(task);
 161 }
 162
 163
 164 void qio_task_set_error(QIOTask *task,
 165                         Error *err)
 166 {
 167     error_propagate(&task->err, err);
 168 }
 169
 170
 171 bool qio_task_propagate_error(QIOTask *task,
 172                               Error **errp)
 173 {
 174     if (task->err) {
 175         error_propagate(errp, task->err);
 176         task->err = NULL;
 177         return true;
 178     }
 179
 180     return false;
 181 }
 182
 183
 184 void qio_task_set_result_pointer(QIOTask *task,
 185                                  gpointer result,
 186                                  GDestroyNotify destroy)
 187 {
 188     task->result = result;
 189     task->destroyResult = destroy;
 190 }
 191
 192
 193 gpointer qio_task_get_result_pointer(QIOTask *task)
 194 {
 195     return task->result;
 196 }
 197
 198
 199 Object *qio_task_get_source(QIOTask *task)
 200 {
 201     return task->source;
 202 }