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     Error *err;
  81     int ret;
  82 };
  83
  84
  85 static gboolean gio_task_thread_result(gpointer opaque)
  86 {
  87     struct QIOTaskThreadData *data = opaque;
  88
  89     trace_qio_task_thread_result(data->task);
  90     if (data->err) {
  91         qio_task_set_error(data->task, data->err);
  92     }
  93     qio_task_complete(data->task);
  94
  95     if (data->destroy) {
  96         data->destroy(data->opaque);
  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
 109     trace_qio_task_thread_run(data->task);
 110     data->ret = data->worker(data->task, &data->err, data->opaque);
 111     if (data->ret < 0 && data->err == NULL) {
 112         error_setg(&data->err, "Task worker failed but did not set an error");
 113     }
 114
 115     /* We're running in the background thread, and must only
 116      * ever report the task results in the main event loop
 117      * thread. So we schedule an idle callback to report
 118      * the worker results
 119      */
 120     trace_qio_task_thread_exit(data->task);
 121     g_idle_add(gio_task_thread_result, data);
 122     return NULL;
 123 }
 124
 125
 126 void qio_task_run_in_thread(QIOTask *task,
 127                             QIOTaskWorker worker,
 128                             gpointer opaque,
 129                             GDestroyNotify destroy)
 130 {
 131     struct QIOTaskThreadData *data = g_new0(struct QIOTaskThreadData, 1);
 132     QemuThread thread;
 133
 134     data->task = task;
 135     data->worker = worker;
 136     data->opaque = opaque;
 137     data->destroy = destroy;
 138
 139     trace_qio_task_thread_start(task, worker, opaque);
 140     qemu_thread_create(&thread,
 141                        "io-task-worker",
 142                        qio_task_thread_worker,
 143                        data,
 144                        QEMU_THREAD_DETACHED);
 145 }
 146
 147
 148 void qio_task_complete(QIOTask *task)
 149 {
 150     task->func(task, task->opaque);
 151     trace_qio_task_complete(task);
 152     qio_task_free(task);
 153 }
 154
 155
 156 void qio_task_set_error(QIOTask *task,
 157                         Error *err)
 158 {
 159     error_propagate(&task->err, err);
 160 }
 161
 162
 163 bool qio_task_propagate_error(QIOTask *task,
 164                               Error **errp)
 165 {
 166     if (task->err) {
 167         error_propagate(errp, task->err);
 168         return true;
 169     }
 170
 171     return false;
 172 }
 173
 174
 175 void qio_task_set_result_pointer(QIOTask *task,
 176                                  gpointer result,
 177                                  GDestroyNotify destroy)
 178 {
 179     task->result = result;
 180     task->destroyResult = destroy;
 181 }
 182
 183
 184 gpointer qio_task_get_result_pointer(QIOTask *task)
 185 {
 186     return task->result;
 187 }
 188
 189
 190 Object *qio_task_get_source(QIOTask *task)
 191 {
 192     return task->source;
 193 }