Timer Utilities

[iperf] / compat / delay.cpp

diff --git a/compat/delay.cpp b/compat/delay.cpp
index 9fc69c68b2d2235560b250bbfdb06061c3d1b990..5d42469193077630607e30271fd691f21b353e1a 100644 (file)
--- a/compat/delay.cpp
+++ b/compat/delay.cpp
@@ -51,19 +51,31 @@
  * ------------------------------------------------------------------- */
 
 #include "Timestamp.hpp"
-
+#include "util.h"
 #include "delay.hpp"
 
 /* -------------------------------------------------------------------
- * A micro-second delay function. This uses gettimeofday (underneith
- * the Timestamp) which has a resolution of upto microseconds. I've
- * found it's good to within about 10 usecs.
- * I used to do calibration, but iperf automatically adjusts itself
- * so that isn't necesary, and it causes some problems if the
- * calibration adjustment is larger than your sleep time.
+ * A micro-second delay function.
  * ------------------------------------------------------------------- */
+void delay_loop(unsigned long usec)
+{
+#ifdef SLEEP_VIA_SELECT
+     // This is a hack but works apparently quite well
+     // I found that it sometimes under-estimates the timeout
+     struct timeval tv;
+
+     tv.tv_sec = 0;
+     tv.tv_usec = usec;
 
-void delay_loop( unsigned long usec ) {
+     select(1, (fd_set *) 0, (fd_set *) 0, (fd_set *) 0, &tv);
+#elif defined(SLEEP_OLD_METHOD)
+    /* Tis uses gettimeofday (underneath the Timestamp), which has a
+     * resolution of upto microseconds. I've found it's good to within
+     * about 10 usecs. I used to do calibration, but iperf automatically
+     * adjusts itself so that isn't necesary, and it causes some problems
+     * if the calibration adjustment is larger than your sleep time.
+     * Note: I found this has problems - if the loop gets interrupted,
+     * long sleeps can result. I found up to 50..60msec. -- Gerrit */
     Timestamp end;
     end.add( usec * 1e-6 );
 
@@ -71,4 +83,14 @@ void delay_loop( unsigned long usec ) {
     while ( now.before( end ) ) {
         now.setnow();
     }
+#else
+    // This is preferred; it is even better than usleep (see manpage).
+    struct timespec ts;
+
+    ts.tv_sec = 0;
+    ts.tv_nsec = usec * 1000L;
+
+    if (nanosleep(&ts, NULL) < 0)
+        WARN_errno(1, "nanosleep");
+#endif
 }