gthread使用注意

ACTom · 发表于 2011-7-11 01:25:05

转自：http://blog.csdn.net/c_spark/article/details/4742919

1、初始化gthread
   if (!g_thread_supported ()) //如果gthread没有被初始化
         g_thread_init (NULL);  //进行初始化
   gdk_threads_init ();       //初始化GDK多线程，这样可以在多线程中使用成对的gdk_threads_enter()和gdk_thread_leave(),在Gtk程序保证       gdk_threads_init()在main loop执行之前执行，为了保证线程安全应该在gtk_init()之前调用，g_thread_init()必须在函数gdk_threads_init()之前执行。
2、gdk_threads_enter()和gdk_threads_leave()
  　gdk_threads_enter()这是一宏定义，占领临界区，这样使Gdk和Gtk+函数在多线程中被安全的调用而不会造成竞争条件，保证数据安全，一次只能有一线程访问临界区。gdk_threads_leave释放对当前临界区访问。
   在调用任何与gtk相关函数时，需要使用gdk_threads_enter()和gdk_threads_leave()成对的宏，保证当前函数的的调用只可能在一个线程中。
3、示例如下：

#include <glib.h>
#include <gtk/gtk.h>
#include <libgnomevfs/gnome-vfs.h>
#define BUF_SIZE 4096
GtkWidget *window;
GtkWidget *image = NULL;
GtkWidget *vbox = NULL;
const gchar *uri = "/home/cspark/logo-large.png";
void callback (void)
{
g_print ("%d %s/n", __LINE__, __FUNCTION__);
}
void
thread_func (GtkWidget *button)
{
int i;
for (i = 0; i <= 20; i++)
{
sleep (1);
gchar *s = g_strdup_printf ("Test %d", i);
gdk_threads_enter ();
gtk_button_set_label (GTK_BUTTON (button), s);
gdk_threads_leave ();
if (s) {
g_free (s);
s = NULL;
}
}
}
void
load_image ()
{
GnomeVFSHandle *handle;
GnomeVFSResult result;
GdkPixbufLoader *loader;
GdkPixbuf *pixbuf;
gchar buffer[BUF_SIZE];
GnomeVFSFileSize bytes_read;
result = gnome_vfs_open (&handle, uri, GNOME_VFS_OPEN_READ);
loader = gdk_pixbuf_loader_new ();
while (result == GNOME_VFS_OK) {
result = gnome_vfs_read (handle, buffer,
BUF_SIZE, &bytes_read);
gdk_pixbuf_loader_write (loader, buffer, bytes_read, NULL);
sleep (2);
}
gdk_pixbuf_loader_close (loader, NULL);
pixbuf = gdk_pixbuf_loader_get_pixbuf (loader);
if (!pixbuf) {
g_print ("pixbuf is NULl");
return;
}
gdk_threads_enter ();
image = gtk_image_new_from_pixbuf (pixbuf);
gtk_box_pack_start (GTK_BOX (vbox), image, FALSE, FALSE, 0);
gtk_widget_show (image);
gdk_threads_leave ();
}
int main (int argc, char *argv[])
{
if (!g_thread_supported ())
g_thread_init (NULL);
gdk_threads_init();
gdk_threads_enter ();
gtk_init (&argc, &argv);
gnome_vfs_init ();
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "destroy", gtk_main_quit, NULL);
GtkWidget *button = NULL;
button = gtk_button_new_with_label ("Test Mutilate GThread");
vbox = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
g_signal_connect (button, "clicked", (GCallback)(callback), NULL);
gtk_widget_show (button);
gtk_container_add (GTK_CONTAINER (window), vbox);
gtk_widget_show_all (window);
g_thread_create ((GThreadFunc) (load_image), NULL, FALSE, NULL);
g_thread_create ((GThreadFunc) (thread_func), button, FALSE, NULL);
gtk_main ();
gdk_threads_leave ();
return 0;
}

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Makefile:

view plain

CC=gcc
CFLAGS = `pkg-config --cflags gtk+-2.0 gthread-2.0 gnome-vfs-2.0` -g
LDFLAGS = `pkg-config --libs gtk+-2.0 gthread-2.0 gnome-vfs-2.0` -rdynamic
SRC=gnomevfs-test.c
test:$(SRC)
$(CC) $(CFLAGS) $(LDFLAGS) $(SRC) -o test

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