5_05_GLib库入门与实践_异步队列

简介

在数据类型里面介绍过双端队列，双端队列没有线程和锁的概念，需要调用者自行保证数据同步性，本章要介绍的是异步队列，本身具有多线程同步特性，非常方便使用。

数据结构

异步队列的数据结构不透明，只可以整体使用它，无法单独引用其内部的成员。

typedef struct _GAsyncQueue GAsyncQueue;

函数列表

GAsyncQueue *
g_async_queue_new ()
GAsyncQueue *
g_async_queue_new_full ()
GAsyncQueue *
g_async_queue_ref ()
void
g_async_queue_unref ()
void
g_async_queue_push ()
void
g_async_queue_push_sorted ()
void
g_async_queue_push_front ()
gboolean
g_async_queue_remove ()
gpointer
g_async_queue_pop ()
gpointer
g_async_queue_try_pop ()
gpointer
g_async_queue_timeout_pop ()
gint
g_async_queue_length ()
void
g_async_queue_sort ()
void
g_async_queue_lock ()
void
g_async_queue_unlock ()
void
g_async_queue_ref_unlocked ()
void
g_async_queue_unref_and_unlock ()
void
g_async_queue_push_unlocked ()
void
g_async_queue_push_sorted_unlocked ()
void
g_async_queue_push_front_unlocked ()
gboolean
g_async_queue_remove_unlocked ()
gpointer
g_async_queue_pop_unlocked ()
gpointer
g_async_queue_try_pop_unlocked ()
gpointer
g_async_queue_timeout_pop_unlocked ()
gint
g_async_queue_length_unlocked ()
void
g_async_queue_sort_unlocked ()
gpointer
g_async_queue_timed_pop ()
gpointer
g_async_queue_timed_pop_unlocked ()

函数功能分类

创建

// 最简单的异步队列创建函数
GAsyncQueue *
g_async_queue_new ()
// 带节点释放函数的异步队列创建函数
GAsyncQueue *
g_async_queue_new_full ()

加解锁

// 异步队列的函数大多有两个版本，一个是带锁版本，一个是不带锁版本
// 如果使用的是不带锁版本，需要先对异步队列lock，使其获得锁，才可以调用无锁函数，执行完之后，再解锁
void
g_async_queue_lock ()
void
g_async_queue_unlock ()

入队列

// 最常用的入队列操作函数
void
g_async_queue_push ()
// 将数据入队列到指定位置，此函数要求队列原来就是有序的，执行完入队列操作后，队列仍保持有序
void
g_async_queue_push_sorted ()
// 将数据入队列到队列最开始位置
void
g_async_queue_push_front ()
// 下面三个是入队列的无锁操作函数，和上面三个的作用相同，但需要配合g_async_queue_lock和g_async_queue_unlock使用。
void
g_async_queue_push_unlocked ()
void
g_async_queue_push_sorted_unlocked ()
void
g_async_queue_push_front_unlocked ()

出队列

// 最常用的出队列操作函数
gpointer
g_async_queue_pop ()
// 尝试出队列，此函数不会阻塞，队列中没有数据会立即返回
gpointer
g_async_queue_try_pop ()
// 尝试出队列，阻塞指定时间，超时后返回
gpointer
g_async_queue_timeout_pop ()
// 下面三个是出队列的无锁操作函数，和上面三个的作用相同，但需要配合g_async_queue_lock和g_async_queue_unlock使用。
gpointer
g_async_queue_pop_unlocked ()
gpointer
g_async_queue_try_pop_unlocked ()
gpointer
g_async_queue_timeout_pop_unlocked ()

排序

// 队列内数据排序，有锁和无锁两个版本
void
g_async_queue_sort ()
void
g_async_queue_sort_unlocked ()

测长

// 返回队列长度，有锁和无锁两个版本
gint
g_async_queue_length ()
gint
g_async_queue_length_unlocked ()

移除

// 将一个元素从队列移除，有锁和无锁两个版本
gboolean
g_async_queue_remove ()
gboolean
g_async_queue_remove_unlocked ()

引用解引用

// GLib特有的引用和解引用函数，有锁和无锁两个版本
GAsyncQueue *
g_async_queue_ref ()
void
g_async_queue_unref ()
void
g_async_queue_ref_unlocked ()
void
g_async_queue_unref_and_unlock ()

函数功能说明及综合演示

出队列

g_async_queue_pop函数，如果队列中没有数据，则此接口一直阻塞。

举例验证：push线程延迟2秒向队列发送数据，则pop线程会阻塞2秒，直到队列中有数据。
演示程序见下：
源码见glib_examplesglib_async_queueglib_async_queue_pop

#include <glib.h>
static gpointer test_aqueue_push_func(gpointer data)
{
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
g_print("delay 2 seconds to push data n");
g_usleep(2*1000*1000);
aqueue = (GAsyncQueue *)data;
g_async_queue_push(aqueue, GINT_TO_POINTER(99));
return NULL;
}
static gpointer test_aqueue_pop_func(gpointer data)
{
gpointer val = NULL;
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
val = g_async_queue_pop(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
return NULL;
}
gint main(gint argc, gchar **argv)
{
GThread *thd_push, *thd_pop;
GAsyncQueue *aqueue = NULL;
aqueue = g_async_queue_new();
thd_push = g_thread_new("thd_push", test_aqueue_push_func, aqueue);
thd_pop
= g_thread_new("thd_pop", test_aqueue_pop_func, aqueue);
g_thread_join(thd_push);
g_thread_join(thd_pop);
g_async_queue_unref(aqueue);
return 0;
}

运行结果：

[root@centos7_6 build]# ./glib_async_queue_pop 
test_aqueue_pop_func
test_aqueue_push_func
delay 2 seconds to push data
val: 99
[root@centos7_6 build]# ./glib_async_queue_pop 
test_aqueue_push_func
delay 2 seconds to push data
test_aqueue_pop_func
val: 99

无论是pop线程还是push线程先执行，都是等2秒之后才能取到数据，在这2秒内pop线程阻塞。

异步队列锁

下列函数允许调用者自己处理异步队列的锁。

g_async_queue_lock
g_async_queue_unlock
g_async_queue_push_unlocked
g_async_queue_pop_unlocked

下面举例演示一下上述函数的用法。
源码见glib_examplesglib_async_queueglib_async_queue_locks

#include <glib.h>
static gpointer test_aqueue_push_func(gpointer data)
{
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
g_async_queue_lock(aqueue);
g_async_queue_push_unlocked(aqueue, GINT_TO_POINTER(99));
g_async_queue_unlock(aqueue);
return NULL;
}
static gpointer test_aqueue_pop_func(gpointer data)
{
gpointer val = NULL;
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
g_async_queue_lock(aqueue);
val = g_async_queue_pop_unlocked(aqueue);
g_async_queue_unlock(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
return NULL;
}
gint main(gint argc, gchar **argv)
{
GThread *thd_push, *thd_pop;
GAsyncQueue *aqueue = NULL;
aqueue = g_async_queue_new();
thd_push = g_thread_new("thd_push", test_aqueue_push_func, aqueue);
thd_pop
= g_thread_new("thd_pop", test_aqueue_pop_func, aqueue);
g_thread_join(thd_push);
g_thread_join(thd_pop);
g_async_queue_unref(aqueue);
return 0;
}

运行结果：

[root@centos7_6 build]# ./glib_async_queue_locks
test_aqueue_push_func
test_aqueue_pop_func
val: 99
[root@centos7_6 build]# ./glib_async_queue_locks
test_aqueue_pop_func
test_aqueue_push_func
val: 99

尝试出队列

g_async_queue_try_pop尝试从队列中取出一个元素，如果队列中有数据，则取出，如果队列中无数据，则返回空，此接口不阻塞。

源码见glib_examplesglib_async_queueglib_async_queue_try_pop

#include <glib.h>
static gpointer test_aqueue_push_func(gpointer data)
{
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
g_print("delay 1 seconds to push data n");
g_usleep(1*1000*1000);
aqueue = (GAsyncQueue *)data;
g_async_queue_push(aqueue, GINT_TO_POINTER(99));
return NULL;
}
static gpointer test_aqueue_pop_func(gpointer data)
{
gpointer val = NULL;
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
val = g_async_queue_try_pop(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
g_print("delay 2 seconds to pop data n");
g_usleep(2*1000*1000);
val = g_async_queue_try_pop(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
val = g_async_queue_try_pop(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
return NULL;
}
gint main(gint argc, gchar **argv)
{
GThread *thd_push, *thd_pop;
GAsyncQueue *aqueue = NULL;
aqueue = g_async_queue_new();
thd_push = g_thread_new("thd_push", test_aqueue_push_func, aqueue);
thd_pop
= g_thread_new("thd_pop", test_aqueue_pop_func, aqueue);
g_thread_join(thd_push);
g_thread_join(thd_pop);
g_async_queue_unref(aqueue);
return 0;
}

运行结果：

[root@centos7_6 build]# ./glib_async_queue_try_pop 
test_aqueue_pop_func
val: 0
delay 2 seconds to pop data
test_aqueue_push_func
delay 1 seconds to push data
val: 99
val: 0

尝试出队列无锁版本

g_async_queue_try_pop_unlocked与g_async_queue_try_pop类似，需要自己处理锁。
下面是示例函数：
源码见glib_examplesglib_async_queueglib_async_queue_try_pop_unlocked

#include <glib.h>
static gpointer test_aqueue_push_func(gpointer data)
{
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
g_print("delay 1 seconds to push data n");
g_usleep(1*1000*1000);
aqueue = (GAsyncQueue *)data;
g_async_queue_lock(aqueue);
g_async_queue_push_unlocked(aqueue, GINT_TO_POINTER(99));
g_async_queue_unlock(aqueue);
return NULL;
}
static gpointer test_aqueue_pop_func(gpointer data)
{
gpointer val = NULL;
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
g_async_queue_lock(aqueue);
val = g_async_queue_try_pop_unlocked(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
g_async_queue_unlock(aqueue);
g_print("delay 2 seconds to pop data n");
g_usleep(2*1000*1000);
g_async_queue_lock(aqueue);
val = g_async_queue_try_pop_unlocked(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
g_async_queue_unlock(aqueue);
g_async_queue_lock(aqueue);
val = g_async_queue_try_pop_unlocked(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
g_async_queue_unlock(aqueue);
return NULL;
}
gint main(gint argc, gchar **argv)
{
GThread *thd_push, *thd_pop;
GAsyncQueue *aqueue = NULL;
aqueue = g_async_queue_new();
thd_push = g_thread_new("thd_push", test_aqueue_push_func, aqueue);
thd_pop
= g_thread_new("thd_pop", test_aqueue_pop_func, aqueue);
g_thread_join(thd_push);
g_thread_join(thd_pop);
g_async_queue_unref(aqueue);
return 0;
}

运行结果：

[root@centos7_6 build]# ./glib_async_queue_try_pop_unlocked
test_aqueue_push_func
delay 1 seconds to push data
test_aqueue_pop_func
val: 0
delay 2 seconds to pop data
val: 99
val: 0

可以看到三次try_pop均立即返回，当队列中没有数据时，返回值为空。

超时

g_async_queue_timeout_pop，从异步队列中取数据，阻塞指定时间，超时则退出，返回值为空。
如果队列中有数据，则本函数立即返回。
超时时间为微秒Microsecond（1Second=1*1000Millisecond=1*1000*1000Microsecond）。

下面是演示程序：
源码见glib_examplesglib_async_queueglib_async_queue_timed_pop

#include <glib.h>
static gpointer test_aqueue_push_func(gpointer data)
{
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
g_print("delay 2 seconds to push data n");
g_usleep(2*1000*1000);
aqueue = (GAsyncQueue *)data;
g_async_queue_push(aqueue, GINT_TO_POINTER(99));
return NULL;
}
static gpointer test_aqueue_pop_func(gpointer data)
{
gpointer val = NULL;
guint64 timeout = 0;
GAsyncQueue *aqueue = NULL;
g_print("%s n", __FUNCTION__);
aqueue = (GAsyncQueue *)data;
timeout = 1*1000*1000;
val = g_async_queue_timeout_pop(aqueue, timeout);
g_print("val: %d n", GPOINTER_TO_INT(val));
g_print("delay 2 seconds to pop data again n");
g_usleep(2*1000*1000);
val = g_async_queue_try_pop(aqueue);
g_print("val: %d n", GPOINTER_TO_INT(val));
return NULL;
}
gint main(gint argc, gchar **argv)
{
GThread *thd_push, *thd_pop;
GAsyncQueue *aqueue = NULL;
aqueue = g_async_queue_new();
thd_push = g_thread_new("thd_push", test_aqueue_push_func, aqueue);
thd_pop
= g_thread_new("thd_pop", test_aqueue_pop_func, aqueue);
g_thread_join(thd_push);
g_thread_join(thd_pop);
g_async_queue_unref(aqueue);
return 0;
}

运行结果：

[root@centos7_6 build]# ./glib_async_queue_timed_pop
test_aqueue_push_func
delay 2 seconds to push data
test_aqueue_pop_func
val: 0
delay 2 seconds to pop data again
val: 99

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