From 98341b7b1b36c35a3b3f1d947b44c5ea90c6f358 Mon Sep 17 00:00:00 2001
From: Laurent MAZET <laurent.mazet@thalesgroup.com>
Date: Thu, 2 Oct 2025 19:26:40 +0200
Subject: [PATCH] add latency test for pipe

---
 pipe_lat.c           | 151 +++++++++++++++++++++++++++++++++++++++++++
 pipe.c => pipe_rtt.c |   2 +-
 2 files changed, 152 insertions(+), 1 deletion(-)
 create mode 100644 pipe_lat.c
 rename pipe.c => pipe_rtt.c (98%)

diff --git a/pipe_lat.c b/pipe_lat.c
new file mode 100644
index 0000000..438ff00
--- /dev/null
+++ b/pipe_lat.c
@@ -0,0 +1,151 @@
+/* depend: */
+/* cflags: */
+/* linker: mtime.o test.o stat.o -lm -lrt */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <pthread.h>
+#include <unistd.h>
+
+#include "mtime.h"
+#include "test.h"
+
+/* global variables */
+
+dts_t *deltas = NULL;
+int nb_measurements = 0;
+
+char *message = "Pipe latency";
+void (*usage_ext) (FILE *) = NULL;
+int (*parse_arg_ext) (char *) = NULL;
+
+#define MAXBUF 1024
+
+ts_t ts1;
+ts_t ts2;
+int rc = 0;
+int pipefd[2] = { 0 };
+
+pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void *ping (__attribute__((unused)) void *arg)
+{
+
+    int fdin = dup (pipefd[0]);
+    int fdout = dup (pipefd[1]);
+
+    pthread_mutex_lock (&mutex);
+    pthread_mutex_unlock (&mutex);
+
+    printf ("Sending ping...\n");
+    for (int i = 0; i < nb_measurements; i++) {
+
+        char buffer[MAXBUF] = { 0 };
+        sprintf (buffer, "ping %d", i);
+
+        sys_timestamp (&ts1);
+
+        if (write (fdout, buffer, strlen (buffer) + 1) == -1) {
+            fprintf (stderr, "ping error: write (%d)\n", i);
+            rc = 1;
+            return NULL;
+        }
+        //printf ("write '%s'\n", buffer);
+
+        if (read (fdin, buffer, sizeof(buffer)) == -1) {
+            fprintf (stderr, "ping error: read (%d)\n", i);
+            rc = 1;
+            return NULL;
+        }
+        //printf ("read '%s'\n", buffer);
+
+        sys_timestamp (&ts2);
+        deltas[i] = diff_timestamp (&ts2, &ts1);
+    }
+
+    close (fdin);
+    close (fdout);
+
+    return NULL;
+}
+
+void *pong (__attribute__((unused)) void *arg)
+{
+
+    int fdin = dup (pipefd[0]);
+    int fdout = dup (pipefd[1]);
+
+    pthread_mutex_unlock (&mutex);
+
+    printf ("Responding pong...\n");
+    for (int i = 0; i < nb_measurements; i++) {
+
+        char buffer[MAXBUF] = { 0 };
+
+        if (read (fdin, buffer, sizeof(buffer)) == -1) {
+            fprintf (stderr, "ping error: read (%d)\n", i);
+            rc = 1;
+            return NULL;
+        }
+        //printf ("read '%s'\n", buffer);
+
+        sys_timestamp (&ts2);
+        deltas[i] = diff_timestamp (&ts2, &ts1);
+
+        sys_timestamp (&ts1);
+
+        if (write (fdout, buffer, strlen (buffer) + 1) == -1) {
+            fprintf (stderr, "ping error: write (%d)\n", i);
+            rc = 1;
+            return NULL;
+        }
+        //printf ("write '%s'\n", buffer);
+    }
+
+    close (fdin);
+    close (fdout);
+
+    return NULL;
+}
+
+int test (dts_t *buffer, int nb)
+{
+
+    /* set global variables */
+
+    deltas = buffer;
+    nb_measurements = nb;
+
+    /* pipe test */
+
+    if (pipe (pipefd) == -1) {
+        fprintf (stderr, "error: pipe\n");
+        return 1;
+    }
+
+    pthread_mutex_lock (&mutex);
+
+    pthread_t tid1;
+    if (pthread_create (&tid1, NULL, ping, NULL) != 0) {
+        fprintf (stderr, "error on pthread_create\n");
+        return 1;
+    }
+
+    pthread_t tid2;
+    if (pthread_create (&tid2, NULL, pong, NULL) != 0) {
+        fprintf (stderr, "error on pthread_create\n");
+        return 1;
+    }
+
+    pthread_join (tid1, NULL);
+    pthread_join (tid2, NULL);
+
+    close (pipefd[0]);
+    close (pipefd[1]);
+
+    pthread_mutex_destroy (&mutex);
+
+    return rc;
+}
diff --git a/pipe.c b/pipe_rtt.c
similarity index 98%
rename from pipe.c
rename to pipe_rtt.c
index 65684b0..30a7679 100644
--- a/pipe.c
+++ b/pipe_rtt.c
@@ -18,7 +18,7 @@
 dts_t *deltas = NULL;
 int nb_measurements = 0;
 
-char *message = "pipe";
+char *message = "Pipe RTT";
 void (*usage_ext) (FILE *) = NULL;
 int (*parse_arg_ext) (char *) = NULL;
 
-- 
2.30.2