dispatch_debug应该如何使用？

Question

我正在努力解决我的GCD代码中的死锁问题.然后我dispatch_debug在头文件中看到了这个函数<dispatch/object.h>.

/*!
 * @function dispatch_debug
 *
 * @abstract
 * Programmatically log debug information about a dispatch object.
 *
 * @param object
 * The object to introspect.
 *
 * @param message
 * The message to log above and beyond the introspection.
 */
__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_4_0)
DISPATCH_EXPORT DISPATCH_NONNULL2 DISPATCH_NOTHROW __attribute__((__format__(printf,2,3)))
void
dispatch_debug(dispatch_object_t object, const char *message, ...);

但我无法做任何事情.我希望它会打印出状态并锁定或类似的东西.

这是我如何使用它:

grabber_queue = dispatch_queue_create("com.unpaq.tvguideplus.grabber", NULL);
dispatch_debug(grabber_queue, "grabber queue");

Answer 1

• Grand Central Dispatch(GCD)参考

dispatch_debug

调试信息记录到控制台日志中.此信息可用作调试工具,以在调用dispatch_debug函数时查看调度对象的内部状态(当前引用计数,暂停计数等).

dispatch_debug将消息发送到syslog.所以,

grabber_queue = dispatch_queue_create("com.unpaq.tvguideplus.grabber", NULL);
dispatch_debug(grabber_queue, "grabber queue");

此代码将在system.log中打印如下.

May 13 08:50:17 hostname exefile[53164]: com.unpaq.tvguideplus.grabber[0x6200e10] = {
 xrefcnt = 0x1, refcnt = 0x1, suspend_cnt = 0x0, locked = 0, target =
 com.apple.root.default-overcommit-priority[0x1af0700], width = 0x0, running = 0x0,
 barrier = 0 }: grabber queueMay

它不会出现在Xcode调试控制台中.您可以在iPhone模拟器上的/Applications/Utilities/Console.app system.log中找到,或者在iPhone,iPod touch和iPad上的Xcode组织器中看到.

顺便说一下,GCD是开源的.它通过libdispatch分发.dispatch_debug包含在src/object.c中.

• src/object.c - dispatch_debug