From 838f8b19543d49731aa140efbdaefc381331f850 Mon Sep 17 00:00:00 2001
From: Ryan Zezeski <ryan@zinascii.com>
Date: Wed, 18 Nov 2015 15:03:28 -0500
Subject: [PATCH] Add spin loop recv option

---
 Makefile  |  3 ++-
 seqtest.c | 39 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 0b2e72c..d9680ba 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 UNAME		=$(shell uname)
 
-CFLAGS_COMMON	=-std=gnu99 -Wall -Werror
+# -pthread needed for MT errno
+CFLAGS_COMMON	=-std=gnu99 -Wall -Werror -pthread
 CFLAGS_Linux	=-D _GNU_SOURCE -D _XOPEN_SOURCE=700
 CFLAGS_SunOS	=-D __EXTENSIONS__ -D _XOPEN_SOURCE=600
 CFLAGS		+=$(CFLAGS_COMMON) $(CFLAGS_$(UNAME))
diff --git a/seqtest.c b/seqtest.c
index 1744283..b5de41a 100644
--- a/seqtest.c
+++ b/seqtest.c
@@ -125,6 +125,7 @@ typedef struct test {
 	struct addrinfo *lai;		/* local addr to bind (client only) */
 	socklen_t	addrlen;
 	sample_t	*samples;
+	int		spin;		/* spin loop recv flag */
 } test_t;
 
 /*
@@ -216,6 +217,29 @@ range(uint32_t minval, uint32_t maxval)
 	return (val);
 }
 
+/*
+ * Receive len bytes into buf. If the t->spin flag is set a spin loop
+ * is used to receive. Otherwise a blocking recv() is performed. The
+ * return value is that of the recv() call.
+ */
+static ssize_t
+st_recv(test_t *t, void *buf, size_t len)
+{
+	ssize_t rv = 0;
+
+	if (t->spin == 1) {
+		while (((rv = recv(t->sock, buf, len, MSG_DONTWAIT)) == -1)) {
+			if (errno != EAGAIN)
+				break;
+		}
+
+	} else {
+		rv = recv(t->sock, buf, len, 0);
+	}
+
+	return (rv);
+}
+
 /*
  * senderreceiver is a pthread worker that sends a single message and expects
  * a reply.
@@ -295,8 +319,10 @@ senderreceiver(void *arg)
 			} else {
 				break;
 			}
-			rv = recv(t->sock, rptr, resid, 0);
+
+			rv = st_recv(t, rptr, resid);
 			now = gethrtime();
+
 			if (rv < 0) {
 				perror("rcvr/recv");
 				goto out;
@@ -543,8 +569,10 @@ replier(void *arg)
 			} else {
 				break;
 			}
-			rv = recv(t->sock, rptr, resid, 0);
+
+			rv = st_recv(t, rptr, resid);
 			now = gethrtime();
+
 			if (rv < 0) {
 				perror("replier/recv");
 				goto out;
@@ -808,6 +836,7 @@ main(int argc, char **argv)
 	uint32_t rintvl;
 	uint32_t nthreads;
 	uint32_t count;
+	int opt_l = 0;
 	enum mode mode;
 	int nais;
 	struct addrinfo **ais;
@@ -826,11 +855,14 @@ main(int argc, char **argv)
 	/* initialize the timer */
 	(void) randtime();
 
-	while ((c = getopt(argc, argv, "o:srdS")) != EOF) {
+	while ((c = getopt(argc, argv, "o:lsrdS")) != EOF) {
 		switch (c) {
 		case 'd':
 			debug++;
 			break;
+		case 'l':
+			opt_l = 1;
+			break;
 		case 's':
 			mode = MODE_ASYNC_SEND;
 			break;
@@ -1096,6 +1128,7 @@ main(int argc, char **argv)
 		t->rseqno = 0;
 		t->sseqno = 0;
 		t->samples = calloc(count, sizeof (sample_t));
+		t->spin = opt_l;
 
 		if (mode == MODE_ASYNC_SEND) {
 			t->addr = addrs[(i / 2) % naddrs];