我正在将flock()用于进程间命名的互斥锁(即某些进程可以决定对"some_name"进行锁定,这是通过在temp目录中锁定名为"some_name"的文件来实现的:
lockfile = "/tmp/some_name.lock";
fd = open(lockfile, O_CREAT);
flock(fd, LOCK_EX);
do_something();
unlink(lockfile);
flock(fd, LOCK_UN);
应该在某个时候删除锁定文件,以避免使用数百个文件填充临时目录.
但是,此代码中存在明显的竞争条件; 进程A,B和C的示例:
A opens file
A locks file
B opens file
A unlinks file
A unlocks file
B locks file (B holds a lock on the deleted file)
C opens file (a new file one is created)
C locks file (two processes hold the same named mutex !)
有没有办法在某些时候删除锁定文件而不引入这种竞争条件？