git daemon: avoid waking up too often
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> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Jul 22, 2008 at 23:03 UTC
f9bbefc701e319983bb8e13df8d615293c6f386a
1 file changed
+11
-14
daemon.c
+11
-14
@@ -16,6 +16,7 @@
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static int log_syslog;
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static int verbose;
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static int reuseaddr;
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+static int child_handler_pipe[2];
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static const char daemon_usage[] =
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"git daemon [--verbose] [--syslog] [--export-all]\n"
@@ -788,6 +789,7 @@ static void child_handler(int signo)
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pid = -pid;
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dead_child[reaped % MAX_CHILDREN] = pid;
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children_reaped = reaped + 1;
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+ write(child_handler_pipe[1], &status, 1);
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continue;
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}
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break;
@@ -933,29 +935,24 @@ static int service_loop(int socknum, int *socklist)
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struct pollfd *pfd;
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int i;
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- pfd = xcalloc(socknum, sizeof(struct pollfd));
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+ if (pipe(child_handler_pipe) < 0)
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+ die ("Could not set up pipe for child handler");
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+
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+ pfd = xcalloc(socknum + 1, sizeof(struct pollfd));
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for (i = 0; i < socknum; i++) {
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pfd[i].fd = socklist[i];
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pfd[i].events = POLLIN;
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}
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+ pfd[socknum].fd = child_handler_pipe[0];
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+ pfd[socknum].events = POLLIN;
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signal(SIGCHLD, child_handler);
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for (;;) {
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int i;
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- int timeout;
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- /*
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- * This 1-sec timeout could lead to idly looping but it is
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- * here so that children culled in child_handler() are reported
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- * without too much delay. We could probably set up a pipe
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- * to ourselves that we poll, and write to the fd from child_handler()
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- * to wake us up (and consume it when the poll() returns...
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- */
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- timeout = (children_spawned != children_deleted) ? 1000 : -1;
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- i = poll(pfd, socknum, timeout);
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- if (i < 0) {
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+ if (poll(pfd, socknum + 1, -1) < 0) {
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if (errno != EINTR) {
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error("poll failed, resuming: %s",
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strerror(errno));
@@ -963,9 +960,9 @@ static int service_loop(int socknum, int *socklist)
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}
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continue;
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}
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- if (i == 0) {
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+ if (pfd[socknum].revents & POLLIN) {
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+ read(child_handler_pipe[0], &i, 1);
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check_dead_children();
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- continue;
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}
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for (i = 0; i < socknum; i++) {