From 695605b5080e1957bd9dab1fed35a7fee9814297 Mon Sep 17 00:00:00 2001 From: "Stephen R. van den Berg" Date: Thu, 14 Aug 2008 20:02:20 +0200 Subject: 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 Signed-off-by: Junio C Hamano --- daemon.c | 55 +++++++++++++++++++++++-------------------------------- 1 file changed, 23 insertions(+), 32 deletions(-) diff --git a/daemon.c b/daemon.c index 3e663a877c..3abacfd9d9 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]; -- cgit v1.2.3