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authorStephen R. van den Berg <srb@cuci.nl>2008-08-14 20:02:20 +0200
committerJunio C Hamano <gitster@pobox.com>2008-08-17 17:43:53 -0700
commit695605b5080e1957bd9dab1fed35a7fee9814297 (patch)
tree431e52d4942526f47a76a02237ceadff2a6b2932
parent6a992e9e1da08af3e36ab90d5f5b7ee8077630ce (diff)
downloadgit-695605b5080e1957bd9dab1fed35a7fee9814297.tar.gz
git-695605b5080e1957bd9dab1fed35a7fee9814297.tar.xz
git-daemon: Simplify dead-children reaping logic
Move almost all code out of the child_handler() into check_dead_children(). The fact that systemcalls get interrupted by signals allows us to make the SIGCHLD signal handler almost a no-op by simply running check_dead_children() right before waiting on poll(). In case some systems do not interrupt systemcalls upon signal receipt, all zombies will eventually be collected before the next poll() cycle. Signed-off-by: Stephen R. van den Berg <srb@cuci.nl> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--daemon.c55
1 files changed, 23 insertions, 32 deletions
diff --git a/daemon.c b/daemon.c
index 3e663a877..3abacfd9d 100644
--- a/daemon.c
+++ b/daemon.c
@@ -16,7 +16,6 @@
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"
@@ -680,6 +679,21 @@ static void check_dead_children(void)
{
unsigned spawned, reaped, deleted;
+ for (;;) {
+ int status;
+ pid_t pid = waitpid(-1, &status, WNOHANG);
+
+ if (pid > 0) {
+ unsigned reaped = children_reaped;
+ if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
+ pid = -pid;
+ dead_child[reaped % MAX_CHILDREN] = pid;
+ children_reaped = reaped + 1;
+ continue;
+ }
+ break;
+ }
+
spawned = children_spawned;
reaped = children_reaped;
deleted = children_deleted;
@@ -760,21 +774,10 @@ static void handle(int incoming, struct sockaddr *addr, int addrlen)
static void child_handler(int signo)
{
- for (;;) {
- int status;
- pid_t pid = waitpid(-1, &status, WNOHANG);
-
- if (pid > 0) {
- unsigned reaped = children_reaped;
- if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
- pid = -pid;
- dead_child[reaped % MAX_CHILDREN] = pid;
- children_reaped = reaped + 1;
- write(child_handler_pipe[1], &status, 1);
- continue;
- }
- break;
- }
+ /* Otherwise empty handler because systemcalls will get interrupted
+ * upon signal receipt
+ * SysV needs the handler to be rearmed
+ */
signal(SIGCHLD, child_handler);
}
@@ -917,24 +920,21 @@ static int service_loop(int socknum, int *socklist)
struct pollfd *pfd;
int i;
- if (pipe(child_handler_pipe) < 0)
- die ("Could not set up pipe for child handler");
-
- pfd = xcalloc(socknum + 1, sizeof(struct pollfd));
+ pfd = xcalloc(socknum, 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);
for (;;) {
int i;
- if (poll(pfd, socknum + 1, -1) < 0) {
+ check_dead_children();
+
+ if (poll(pfd, socknum, -1) < 0) {
if (errno != EINTR) {
logerror("Poll failed, resuming: %s",
strerror(errno));
@@ -942,10 +942,6 @@ static int service_loop(int socknum, int *socklist)
}
continue;
}
- if (pfd[socknum].revents & POLLIN) {
- read(child_handler_pipe[0], &i, 1);
- check_dead_children();
- }
for (i = 0; i < socknum; i++) {
if (pfd[i].revents & POLLIN) {
@@ -1036,11 +1032,6 @@ int main(int argc, char **argv)
gid_t gid = 0;
int i;
- /* Without this we cannot rely on waitpid() to tell
- * what happened to our children.
- */
- signal(SIGCHLD, SIG_DFL);
-
for (i = 1; i < argc; i++) {
char *arg = argv[i];