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- commit 487b38e86c08431bc5f48aac72c8d753ee23cb03
- Author: Willy Tarreau <w@1wt.eu>
- Date: Fri Jul 26 15:10:39 2019 +0200
-
- BUG/MINOR: log: make sure writev() is not interrupted on a file output
-
- Since 1.9 we support sending logs to various non-blocking outputs like
- stdou/stderr or flies, by using writev() which guarantees that it only
- returns after having written everything or nothing. However the syscall
- may be interrupted while doing so, and this is visible when writing to
- a tty during debug sessions, as some logs occasionally appear interleaved
- if an xterm or SSH connection is not very fast. Performance here is not a
- critical concern, log correctness is. Let's simply take the logger's lock
- around the writev() call to prevent multiple senders from stepping onto
- each other's toes.
-
- This may be backported to 2.0 and 1.9.
-
- (cherry picked from commit 9fbcb7e2e9c32659ab11927394fec2e160be2d0b)
- Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
-
- diff --git a/src/log.c b/src/log.c
- index ef999d13..99f185e4 100644
- --- a/src/log.c
- +++ b/src/log.c
- @@ -1672,8 +1672,15 @@ send:
- iovec[7].iov_len = 1;
-
- if (logsrv->addr.ss_family == AF_UNSPEC) {
- - /* the target is a direct file descriptor */
- + /* the target is a direct file descriptor. While writev() guarantees
- + * to write everything, it doesn't guarantee that it will not be
- + * interrupted while doing so. This occasionally results in interleaved
- + * messages when the output is a tty, hence the lock. There's no real
- + * performance concern here for such type of output.
- + */
- + HA_SPIN_LOCK(LOGSRV_LOCK, &logsrv->lock);
- sent = writev(*plogfd, iovec, 8);
- + HA_SPIN_UNLOCK(LOGSRV_LOCK, &logsrv->lock);
- }
- else {
- msghdr.msg_name = (struct sockaddr *)&logsrv->addr;
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