Messages in this thread Patch in this message | | | Subject | [PATCH V4 2/5] trace-cmd/msg: Use poll(2) to wait for a message | From | Yoshihiro YUNOMAE <> | Date | Fri, 11 Jul 2014 00:58:29 +0000 |
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Use poll(2) to wait for a message. If a client/server cannot send a message for any reasons, the current server/client will wait in a blocking read operation. So, we use poll(2) for avoiding remaining in a blocking state.
Changes in V4: Change the argument of tracecmd_msg_recv_wait() Fix some typos
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> --- trace-msg.c | 42 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-)
diff --git a/trace-msg.c b/trace-msg.c index 08fa2a6..db48365 100644 --- a/trace-msg.c +++ b/trace-msg.c @@ -395,6 +395,27 @@ error: return -ENOMSG; } +#define MSG_WAIT_MSEC 5000 + +/* + * A return value of 0 indicates time-out + */ +static int tracecmd_msg_recv_wait(int fd, struct tracecmd_msg *msg) +{ + struct pollfd pfd; + int ret; + + pfd.fd = fd; + pfd.events = POLLIN; + ret = poll(&pfd, 1, MSG_WAIT_MSEC); + if (ret < 0) + return -errno; + else if (ret == 0) + return -ETIMEDOUT; + + return tracecmd_msg_recv(fd, msg); +} + static void *tracecmd_msg_buf_access(struct tracecmd_msg *msg, int offset) { return (void *)msg + offset; @@ -405,9 +426,12 @@ static int tracecmd_msg_wait_for_msg(int fd, struct tracecmd_msg *msg) u32 cmd; int ret; - ret = tracecmd_msg_recv(fd, msg); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } cmd = ntohl(msg->cmd); if (cmd == MSG_CLOSE) @@ -487,9 +511,12 @@ int tracecmd_msg_initial_setting(int fd, int *cpus, int *pagesize) u32 cmd; msg = (struct tracecmd_msg *)buf; - ret = tracecmd_msg_recv(fd, msg); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } cmd = ntohl(msg->cmd); if (cmd != MSG_TINIT) { @@ -627,9 +654,12 @@ int tracecmd_msg_collect_metadata(int ifd, int ofd) msg = (struct tracecmd_msg *)buf; do { - ret = tracecmd_msg_recv(ifd, msg); + ret = tracecmd_msg_recv_wait(ifd, msg); if (ret < 0) { - warning("reading client"); + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); + else + warning("reading client"); return ret; }
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