[PATCH] git daemon: avoid waking up too often
- From
Johannes Schindelin <johannes.schindelin@gmx.de>
- Date
- Jul 22, 2008, 21:52 UTC
- Message-ID
- <alpine.DEB.1.00.0807222251570.8986@racer>
To avoid waking up unnecessarily, a pipe is set up that is only ever written to by child_handler(), when a child disconnects, as suggested per Junio.
This avoids waking up the main process every second to see if a child was disconnected.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> ---
I have this in production ever since I posted it the first time, without problems.
Oh, and it removes more lines than it introduces ;-)
daemon.c | 24 +++++++++++------------- 1 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/daemon.c b/daemon.c index 7df41a6..850f6f9 100644 --- a/daemon.c +++ b/daemon.c @@ -16,6 +16,7 @@ static int log_syslog; static int verbose; static int reuseaddr; +static int child_handler_pipe[2]; static const char daemon_usage[] = "git daemon [--verbose] [--syslog] [--export-all]\n" @@ -788,6 +789,7 @@ static void child_handler(int signo) pid = -pid; dead_child[reaped % MAX_CHILDREN] = pid; children_reaped = reaped + 1; + write(child_handler_pipe[1], &status, 1); continue; } break; @@ -933,12 +935,17 @@ static int service_loop(int socknum, int *socklist) struct pollfd *pfd; int i; - pfd = xcalloc(socknum, sizeof(struct pollfd)); + if (pipe(child_handler_pipe) < 0) + die ("Could not set up pipe for child handler"); + + pfd = xcalloc(socknum + 1, sizeof(struct pollfd)); for (i = 0; i < socknum; i++) { pfd[i].fd = socklist[i]; pfd[i].events = POLLIN; } + pfd[socknum].fd = child_handler_pipe[0]; + pfd[socknum].events = POLLIN; signal(SIGCHLD, child_handler); @@ -946,16 +953,7 @@ static int service_loop(int socknum, int *socklist) int i; int timeout; - /* - * This 1-sec timeout could lead to idly looping but it is - * here so that children culled in child_handler() are reported - * without too much delay. We could probably set up a pipe - * to ourselves that we poll, and write to the fd from child_handler() - * to wake us up (and consume it when the poll() returns... - */ - timeout = (children_spawned != children_deleted) ? 1000 : -1; - i = poll(pfd, socknum, timeout); - if (i < 0) { + if (poll(pfd, socknum + 1, -1) < 0) { if (errno != EINTR) { error("poll failed, resuming: %s", strerror(errno)); @@ -963,9 +961,9 @@ static int service_loop(int socknum, int *socklist) } continue; } - if (i == 0) { + if (pfd[socknum].revents & POLLIN) { + read(child_handler_pipe[0], &i, 1); check_dead_children(); - continue; } for (i = 0; i < socknum; i++) {
-- 1.6.0.rc0.22.gf2096d.dirty