3 ms·

pipe(&pipefd); assert(len <= PIPE_BUF); write(pipefd[1], buf, len); Also, if a file is opened O_APPEND, the seek before every write is atomic, but since wr

• geocar 17y ago
  This is a great one: Under POSIX, any write() to a fifo that has at least PIPE_BUF free is atomic. There's a neat trick I'd like to add that takes advantage of this: Multiple clients can use a message whose size divides evenly into PIPE_BUF without any possibility of interleave, and so they do not need to lock. int n=sizeof(struct message); struct message m[n/PIPE_BUF]; assert(sizeof(m)==PIPE_BUF); if(pipe(fds)==-1)abort(); for(i=0;i<cpus;i++){if(!fork())child(fds[1]);} while(r=read(fds[0],m,PIPE_BUF)){for(i=r/n-1;i>=0;--i)handle(m+i);} Each child can write entire messages, without locking and without interleaving, so long as sizeof(struct message)*n is exactly PIPE_BUF. Btw, your pipe(&pipefd) should've been pipe(pipefd) if pipefd is an array of 2 int
• sophacles 17y ago
  Makes logging things easier, and in correct order!