From 08a2de459beb605fa3606b8d9f0ffba6028d7dee Mon Sep 17 00:00:00 2001
From: QuaSoft <info@quasoft.net>
Date: Sun, 6 Mar 2016 16:47:02 +0200
Subject: [PATCH] Add command line option `--forceflush` to allow user to
 request flushing of output at the end of each interval.

Fixes #299
---
 docs/invoking.rst  | 4 ++++
 src/iperf.h        | 1 +
 src/iperf3.1       | 4 ++++
 src/iperf_api.c    | 6 +++++-
 src/iperf_api.h    | 1 +
 src/iperf_locale.c | 1 +
 6 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/docs/invoking.rst b/docs/invoking.rst
index 6048303..2197409 100644
--- a/docs/invoking.rst
+++ b/docs/invoking.rst
@@ -82,6 +82,10 @@ the executable.
    ‐‐logfile file
    send output to a log file.
 
+   --forceflush
+   force flushing output at every interval. Used to avoid buffering when sending
+   output to pipe.
+
    ‐d, ‐‐debug
    emit  debugging  output.  Primarily (perhaps exclusively) of use
    to developers.
diff --git a/src/iperf.h b/src/iperf.h
index ca0a4e2..426565d 100755
--- a/src/iperf.h
+++ b/src/iperf.h
@@ -236,6 +236,7 @@ struct iperf_test
     int       debug;				/* -d option - enable debug */
     int	      get_server_output;		/* --get-server-output */
     int	      udp_counters_64bit;		/* --use-64-bit-udp-counters */
+    int       forceflush; /* --forceflush - flushing output at every interval */
 
     int	      multisend;
 
diff --git a/src/iperf3.1 b/src/iperf3.1
index 272a6f7..5bc3736 100644
--- a/src/iperf3.1
+++ b/src/iperf3.1
@@ -58,6 +58,10 @@ output in JSON format
 .BR --logfile " \fIfile\fR"
 send output to a log file.
 .TP
+.BR --forceflush " "
+force flushing output at every interval.
+Used to avoid buffering when sending output to pipe.
+.TP
 .BR -d ", " --debug " "
 emit debugging output.
 Primarily (perhaps exclusively) of use to developers.
diff --git a/src/iperf_api.c b/src/iperf_api.c
index d7c5749..b374690 100755
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -653,6 +653,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 #endif
 	{"pidfile", required_argument, NULL, 'I'},
 	{"logfile", required_argument, NULL, OPT_LOGFILE},
+	{"forceflush", no_argument, NULL, OPT_FORCEFLUSH},
 	{"get-server-output", no_argument, NULL, OPT_GET_SERVER_OUTPUT},
 	{"udp-counters-64bit", no_argument, NULL, OPT_UDP_COUNTERS_64BIT},
         {"debug", no_argument, NULL, 'd'},
@@ -927,6 +928,9 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 	    case OPT_LOGFILE:
 		test->logfile = strdup(optarg);
 		break;
+	    case OPT_FORCEFLUSH:
+		test->forceflush = 1;
+		break;
 	    case OPT_GET_SERVER_OUTPUT:
 		test->get_server_output = 1;
 		client_flag = 1;
@@ -2582,7 +2586,7 @@ print_interval_results(struct iperf_test *test, struct iperf_stream *sp, cJSON *
 	}
     }
 
-    if (test->logfile)
+    if (test->logfile || test->forceflush)
         iflush(test);
 }
 
diff --git a/src/iperf_api.h b/src/iperf_api.h
index d16cb8a..5a7d40a 100755
--- a/src/iperf_api.h
+++ b/src/iperf_api.h
@@ -50,6 +50,7 @@ struct iperf_stream;
 #define OPT_UDP_COUNTERS_64BIT 4
 #define OPT_CLIENT_PORT 5
 #define OPT_NUMSTREAMS 6
+#define OPT_FORCEFLUSH 7
 
 /* states */
 #define TEST_START 1
diff --git a/src/iperf_locale.c b/src/iperf_locale.c
index ee3a74a..4404059 100644
--- a/src/iperf_locale.c
+++ b/src/iperf_locale.c
@@ -108,6 +108,7 @@ const char usage_longstr[] = "Usage: iperf [-s|-c host] [options]\n"
                            "  -V, --verbose             more detailed output\n"
                            "  -J, --json                output in JSON format\n"
                            "  --logfile f               send output to a log file\n"
+                           "  --forceflush              force flushing output at every interval\n"
                            "  -d, --debug               emit debugging output\n"
                            "  -v, --version             show version information and quit\n"
                            "  -h, --help                show this message and quit\n"