block/aio_task.c

   1 /*
   2  * Aio tasks loops
   3  *
   4  * Copyright (c) 2019 Virtuozzo International GmbH.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "block/aio.h"
  27 #include "block/aio_task.h"
  28
  29 struct AioTaskPool {
  30     Coroutine *main_co;
  31     int status;
  32     int max_busy_tasks;
  33     int busy_tasks;
  34     bool waiting;
  35 };
  36
  37 static void coroutine_fn aio_task_co(void *opaque)
  38 {
  39     AioTask *task = opaque;
  40     AioTaskPool *pool = task->pool;
  41
  42     assert(pool->busy_tasks < pool->max_busy_tasks);
  43     pool->busy_tasks++;
  44
  45     task->ret = task->func(task);
  46
  47     pool->busy_tasks--;
  48
  49     if (task->ret < 0 && pool->status == 0) {
  50         pool->status = task->ret;
  51     }
  52
  53     g_free(task);
  54
  55     if (pool->waiting) {
  56         pool->waiting = false;
  57         aio_co_wake(pool->main_co);
  58     }
  59 }
  60
  61 void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
  62 {
  63     assert(pool->busy_tasks > 0);
  64     assert(qemu_coroutine_self() == pool->main_co);
  65
  66     pool->waiting = true;
  67     qemu_coroutine_yield();
  68
  69     assert(!pool->waiting);
  70     assert(pool->busy_tasks < pool->max_busy_tasks);
  71 }
  72
  73 void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool)
  74 {
  75     if (pool->busy_tasks < pool->max_busy_tasks) {
  76         return;
  77     }
  78
  79     aio_task_pool_wait_one(pool);
  80 }
  81
  82 void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool)
  83 {
  84     while (pool->busy_tasks > 0) {
  85         aio_task_pool_wait_one(pool);
  86     }
  87 }
  88
  89 void coroutine_fn aio_task_pool_start_task(AioTaskPool *pool, AioTask *task)
  90 {
  91     aio_task_pool_wait_slot(pool);
  92
  93     task->pool = pool;
  94     qemu_coroutine_enter(qemu_coroutine_create(aio_task_co, task));
  95 }
  96
  97 AioTaskPool *coroutine_fn aio_task_pool_new(int max_busy_tasks)
  98 {
  99     AioTaskPool *pool = g_new0(AioTaskPool, 1);
 100
 101     assert(max_busy_tasks > 0);
 102
 103     pool->main_co = qemu_coroutine_self();
 104     pool->max_busy_tasks = max_busy_tasks;
 105
 106     return pool;
 107 }
 108
 109 void aio_task_pool_free(AioTaskPool *pool)
 110 {
 111     g_free(pool);
 112 }
 113
 114 int aio_task_pool_status(AioTaskPool *pool)
 115 {
 116     if (!pool) {
 117         return 0; /* Sugar for lazy allocation of aio pool */
 118     }
 119
 120     return pool->status;
 121 }
 122
 123 bool aio_task_pool_empty(AioTaskPool *pool)
 124 {
 125     return pool->busy_tasks == 0;
 126 }