linux,阻塞select是否一定能够被SIGUSR1信号中断？

2008奥运会

原帖由 flw2 于 2007-5-18 20:16 发表

我很讨厌你

Edengundam

原帖由 coconutmm 于 2007-5-18 20:08 发表
其实，我的意思是说，因为select和上一条语句之间，存在时间窗，也学信号就是在这个时间内发生，对于select存在的信号可能已经丢失了

当然会了, APUE上描述的还是很明确, 我们只能通过sigsuspend解决pause这个问题, 但是select确无法解决. ^^
APUE 10.16:

We test each of the global flags before calling select and again if select returns an interrupted system call error. The problem occurs if either signal is caught between the first two if statements and the subsequent call to select. Signals occurring in here are lost, as indicated by the code comment. The signal handlers are called, and they set the appropriate global variable, but the select never returns (unless some data is ready to be read).

What we would like to be able to do is the following sequence of steps, in order.

Block SIGINT and SIGALRM.

Test the two global variables to see whether either signal has occurred and, if so, handle the condition.

Call select (or any other system function, such as read) and unblock the two signals, as an atomic operation.

The sigsuspend function helps us only if step 3 is a pause operation.

wuxiangzhi

原帖由 coconutmm 于 2007-5-18 20:08 发表
其实，我的意思是说，因为select和上一条语句之间，存在时间窗，也学信号就是在这个时间内发生，对于select存在的信号可能已经丢失了

刚好写了个例子，和你说的情况不知道是一回事么。
大概程序是这样的：
..........
pause();
select();
.......

程序应该阻塞在pause ,还未执行到select,这时程序被usr1信号中断，即函数pause()被中断，如果此时发生了select关心的事件，这个事件是不会丢失的，信号处理函数返回后，执行到select， select能够检测到有事件发生。

lanying_wzw

pselect()应该能满足楼主的要求