Add -a option for the master; do not wait for waiters.

os/syncd/GNUmakefile.in

@@ -19,10 +19,10 @@ all:	emulab-syncd emulab-sync
 
 include $(TESTBED_SRCDIR)/GNUmakerules
 
-emulab-syncd:	emulab-syncd.o version.o 
+emulab-syncd:	emulab-syncd.o version.o decls.h
 	$(CC) $(CFLAGS) emulab-syncd.o version.o $(LIBS) -o emulab-syncd
 
-emulab-sync:	emulab-sync.o version.o 
+emulab-sync:	emulab-sync.o version.o decls.h
 	$(CC) $(CFLAGS) emulab-sync.o version.o $(LIBS) -o emulab-sync
 
 version.c: emulab-syncd.c 

os/syncd/decls.h

@@ -13,12 +13,19 @@
  */
 typedef struct {
 	char		name[64];	/* An arbitrary string */
-	int		request;	/* Either init or wait */
+	short		request;	/* Either init or wait */
+	short		flags;		/* See below */
 	int		count;		/* Number of waiters */
 } barrier_req_t;
 
-#define BARRIER_INIT	1
-#define BARRIER_WAIT	2
+/* Request */
+#define BARRIER_INIT		1
+#define BARRIER_WAIT		2
+
+/* Flags */
+#define BARRIER_INIT_NOWAIT	0x1	/* Initializer does not wait! */
+
+/* Default name is not specified */
 #define DEFAULT_BARRIER "barrier"
 
 /* Info */

os/syncd/emulab-sync.c

@@ -44,6 +44,7 @@ char *usagestr =
  " -s server	   Specify a sync server to connect to\n"
  " -p portnum	   Specify a port number to connect to\n"
  " -i count	   Initialize named barrier to count waiters\n"
+ " -a              Master returns immediately when initializing barrier\n"
  " -u		   Use UDP instead of TCP\n"
  "\n";
 
@@ -65,11 +66,15 @@ main(int argc, char **argv)
 	int			useudp  = 0;
 	char			*server = NULL;
 	int			initme  = 0;
+	int			nowait  = 0;
 	char			*barrier= DEFAULT_BARRIER;
 	barrier_req_t		barrier_req;
 	
-	while ((ch = getopt(argc, argv, "ds:p:ui:n:")) != -1)
+	while ((ch = getopt(argc, argv, "ds:p:ui:n:a")) != -1)
 		switch(ch) {
+		case 'a':
+			nowait++;
+			break;
 		case 'd':
 			debug++;
 			break;
@@ -141,10 +146,13 @@ main(int argc, char **argv)
 	/*
 	 * Build up the request structure to send to the server.
 	 */
+	bzero(&barrier_req, sizeof(barrier_req));
 	strcpy(barrier_req.name, barrier);
 	if (initme) {
 		barrier_req.request = BARRIER_INIT;
 		barrier_req.count   = initme;
+		if (nowait)
+			barrier_req.flags = BARRIER_INIT_NOWAIT;
 	}
 	else
 		barrier_req.request = BARRIER_WAIT;

os/syncd/emulab-syncd.c

@@ -25,8 +25,10 @@
 #include "log.h"
 
 int		debug = 0;
+static int	portnum = SERVER_PORTNUM;
 static int      handle_request(int, struct sockaddr_in *, barrier_req_t *,int);
 static int	makesockets(int portnum, int *udpsockp, int *tcpsockp);
+static void     release_client(int sock, struct in_addr ip, int istcp);
 int		client_writeback(int sock, void *buf, int len, int tcp);
 void		client_writeback_done(int sock, struct sockaddr_in *client);
 
@@ -80,7 +82,6 @@ int
 main(int argc, char **argv)
 {
 	int			tcpsock, udpsock, i, fdcount, ch;
-	int			portnum = SERVER_PORTNUM;
 	FILE			*fp;
 	char			buf[BUFSIZ];
 	extern char		build_info[];
@@ -301,7 +302,7 @@ handle_request(int sock, struct sockaddr_in *client,
 {
 	barrier_ctrl_t	   *barrierp = allbarriers;
 	barrier_ctrl_t	   *tmp;
-	int		   i, foo = 1;
+	int		   i;
 
 	/*
 	 * Find the control structure. Since a waiter can check in before
@@ -334,6 +335,15 @@ handle_request(int sock, struct sockaddr_in *client,
 			     inet_ntoa(client->sin_addr),
 			     barrierp->name, barrier_reqp->count,
 			     barrierp->count);
+
+		if (barrier_reqp->flags & BARRIER_INIT_NOWAIT) {
+			info("%s: Barrier Master not waiting: %s\n",
+			     inet_ntoa(client->sin_addr),
+			     barrierp->name);
+			
+			release_client(sock, client->sin_addr, istcp);
+			goto check;
+		}
 	}
 	else if (barrier_reqp->request == BARRIER_WAIT) {
 		barrierp->count -= 1;
@@ -364,36 +374,18 @@ handle_request(int sock, struct sockaddr_in *client,
 	 * value to make it "easy" for the waiter to notice an error,
 	 * say if the server node goes down or the daemon dies.
 	 */
+ check:
 	if (barrierp->count != 0)
 		return 0;
 
 	for (i = 0; i < barrierp->index; i++) {
-		int thissock = barrierp->waiters[i].sock;
-		int err;
-
 		if (debug)
 			info("%s: releasing %s\n", barrierp->name,
 			     inet_ntoa(barrierp->waiters[i].ipaddr));
-				     
-		if (barrierp->waiters[i].istcp) {
-			if ((err = write(thissock, &foo, sizeof(foo))) <= 0) {
-				if (err < 0) {
-					errorc("writing to TCP client");
-				}
-				error("write to TCP client aborted");
-			}
-			close(thissock);
-		}
-		else {
-			client->sin_addr.s_addr =
-				barrierp->waiters[i].ipaddr.s_addr;
-				
-			err = sendto(thissock, &foo, sizeof(foo), 0,
-				     (struct sockaddr *)client,
-				     sizeof(*client));
-			if (err < 0)
-				errorc("writing to UDP client");
-		}
+
+		release_client(barrierp->waiters[i].sock,
+			       barrierp->waiters[i].ipaddr,
+			       barrierp->waiters[i].istcp);
 	}
 
 	/*
@@ -416,3 +408,46 @@ handle_request(int sock, struct sockaddr_in *client,
 	return 0;
 }
 
+/*
+ * Release a single client from a barrier at a time.
+ */
+static void
+release_client(int sock, struct in_addr ipaddr, int istcp)
+{
+	int	err, foo = 1;
+	
+	if (istcp) {
+		if ((err = write(sock, &foo, sizeof(foo))) <= 0) {
+			if (err < 0) {
+				errorc("writing to TCP client");
+			}
+			error("write to TCP client aborted");
+		}
+		close(sock);
+	}
+	else {
+		struct sockaddr_in	client;
+		
+		client.sin_addr    = ipaddr;
+		client.sin_family  = AF_INET;
+		client.sin_port    = htons(portnum);
+
+		err = sendto(sock, &foo, sizeof(foo), 0,
+			     (struct sockaddr *)&client,
+			     sizeof(client));
+		if (err < 0)
+			errorc("writing to UDP client");
+	}
+}
+
+
+
+
+
+
+
+
+
+
+
+