libflow: accommodate Macs

As of today, macOS or OS X still does not implement
clock_nanosleep() according to this project:
https://github.com/ChisholmKyle/PosixMachTiming

libflow.c

@@ -6,7 +6,6 @@
 #include <float.h>
 #include <assert.h>
 #include <math.h>
-#include <time.h>
 #include <sys/time.h>
 
 #include "libflow.h"
@@ -205,37 +204,6 @@ static inline int flush_chunk(const struct flow *fw, int fd)
 	return 0;
 }
 
-static void msleep(double wait_ms)
-{
-	struct timespec req;
-	int ret;
-
-	assert(!clock_gettime(CLOCK_MONOTONIC, &req));
-
-	/* Add @wait_ms to @req. */
-	if (wait_ms > 1000) {
-		time_t sec = wait_ms / 1000;
-		wait_ms -= sec * 1000;
-		assert(wait_ms > 0);
-		req.tv_sec += sec;
-	}
-	req.tv_nsec += wait_ms * 1000000;
-
-	/* Round @req up. */
-	if (req.tv_nsec >= 1000000000) {
-		ldiv_t result = ldiv(req.tv_nsec, 1000000000);
-		req.tv_sec += result.quot;
-		req.tv_nsec = result.rem;
-	}
-
-	do {
-		ret = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
-			&req, NULL);
-	} while (ret == EINTR);
-
-	assert(ret == 0);
-}
-
 /* XXX Avoid duplicate this function, which was copied from libutils.h. */
 static inline uint64_t diff_timeval_us(const struct timeval *t1,
 	const struct timeval *t2)

utils.c

@@ -179,4 +179,46 @@ int posix_fadvise(int fd, off_t offset, off_t len, int advice)
 	}
 }
 
-#endif	/* Apple Macintosh */
+#include <unistd.h> /* For usleep(). */
+
+void msleep(double wait_ms)
+{
+	assert(!usleep(wait_ms * 1000));
+}
+
+#else
+
+#include <time.h> /* For clock_gettime() and clock_nanosleep(). */
+
+void msleep(double wait_ms)
+{
+	struct timespec req;
+	int ret;
+
+	assert(!clock_gettime(CLOCK_MONOTONIC, &req));
+
+	/* Add @wait_ms to @req. */
+	if (wait_ms > 1000) {
+		time_t sec = wait_ms / 1000;
+		wait_ms -= sec * 1000;
+		assert(wait_ms > 0);
+		req.tv_sec += sec;
+	}
+	req.tv_nsec += wait_ms * 1000000;
+
+	/* Round @req up. */
+	if (req.tv_nsec >= 1000000000) {
+		ldiv_t result = ldiv(req.tv_nsec, 1000000000);
+		req.tv_sec += result.quot;
+		req.tv_nsec = result.rem;
+	}
+
+	do {
+		ret = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
+			&req, NULL);
+	} while (ret == EINTR);
+
+	assert(ret == 0);
+}
+
+#endif

utils.h

@@ -24,6 +24,8 @@ static inline int64_t delay_ms(const struct timeval *t1,
 			(t2->tv_usec - t1->tv_usec) / 1000;
 }
 
+void msleep(double wait_ms);
+
 const long *ls_my_files(const char *path, long start_at, long end_at);
 
 void print_header(FILE *f, const char *name);