Rework the handover mechanism to make the old client reject further clients, then send a reconnect, then shutdown and wait before killing it

src/ckpool.c

@@ -784,7 +784,7 @@ int process_exit(ckpool_t *ckp, proc_instance_t *pi, int ret)
 		LOGWARNING("%s %s exiting with return code %d, shutting down!",
 			   ckp->name, pi->processname, ret);
 		send_proc(&ckp->main, "shutdown");
-		sleep(1);
+		cksleep_ms(100);
 		ret = 1;
 	} else /* Should be part of a normal shutdown */
 		LOGNOTICE("%s %s exited normally", ckp->name, pi->processname);
@@ -856,8 +856,8 @@ static void sighandler(int sig)
 	cancel_join_pthread(&ckp->pth_watchdog);
 
 	__shutdown_children(ckp, SIGUSR1);
-	/* Wait a second, then send SIGKILL */
-	sleep(1);
+	/* Wait, then send SIGKILL */
+	cksleep_ms(100);
 	__shutdown_children(ckp, SIGKILL);
 	cancel_pthread(&ckp->pth_listener);
 	exit(0);
@@ -1106,6 +1106,18 @@ static struct option long_options[] = {
 };
 #endif
 
+static void send_recv_path(const char *path, const char *msg)
+{
+	int sockd = open_unix_client(path);
+	char *response;
+
+	send_unix_msg(sockd, msg);
+	response = recv_unix_msg(sockd);
+	LOGWARNING("Received: %s in response to %s request", response, msg);
+	dealloc(response);
+	Close(sockd);
+}
+
 int main(int argc, char **argv)
 {
 	struct sigaction handler;
@@ -1324,13 +1336,15 @@ int main(int argc, char **argv)
 
 		if (sockd > 0 && send_unix_msg(sockd, "getfd")) {
 			ckp.oldconnfd = get_fd(sockd);
-
 			Close(sockd);
-			sockd = open_unix_client(ckp.main.us.path);
-			send_unix_msg(sockd, "shutdown");
+
+			send_recv_path(ckp.main.us.path, "reject");
+			send_recv_path(ckp.main.us.path, "reconnect");
+			send_recv_path(ckp.main.us.path, "shutdown");
+			cksleep_ms(500);
+
 			if (ckp.oldconnfd > 0)
 				LOGWARNING("Inherited old socket with new file descriptor %d!", ckp.oldconnfd);
-			Close(sockd);
 		}
 	}