The current implementation of nanosleep is broken on mingw for several reasons:
1) It requires linking with -lws2_32, as evidenced by these error messages:
gcc-3 -mno-cygwin -g -O2 -L/usr/local/mingw/lib -o test-nanosleep.exe
test-nanosleep.o ../gllib/libgnu.a
../gllib/libgnu.a(select.o): In function `rpl_select':
/home/bruno/testdir2/gllib/select.c:93: undefined reference to
`_wsaenumnetworkeve...@12'
/home/bruno/testdir2/gllib/select.c:360: undefined reference to
`_wsaeventsel...@12'
/home/bruno/testdir2/gllib/select.c:381: undefined reference to `_sel...@20'
/home/bruno/testdir2/gllib/select.c:434: undefined reference to
`_wsaeventsel...@12'
/home/bruno/testdir2/gllib/select.c:435: undefined reference to
`___wsafdis...@8'
/home/bruno/testdir2/gllib/select.c:437: undefined reference to
`___wsafdis...@8'
/home/bruno/testdir2/gllib/select.c:439: undefined reference to
`___wsafdis...@8'
/home/bruno/testdir2/gllib/select.c:414: undefined reference to `_sel...@20'
collect2: ld returned 1 exit status
make[4]: *** [test-nanosleep.exe] Error 1
But there is no good reason to link with a sockets library just to sleep a
certain amount of time.
2) Use of this the 'select' function in wsock2 requires a prior invocation
of WSAStartup() (contained in the 'sockets' module).
Witness: This program
===============================================================================
#include <winsock2.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
int main (int argc, char *argv[])
{
int usecs = atoi (argv[1]);
LARGE_INTEGER pcfreq;
LARGE_INTEGER before, after;
struct timeval timeout;
int ret;
if (!QueryPerformanceFrequency (&pcfreq))
printf ("QueryPerformanceFrequency failed\n");
if (!QueryPerformanceCounter (&before))
printf ("QueryPerformanceCounter failed\n");
timeout.tv_sec = usecs / 1000000;
timeout.tv_usec = usecs % 1000000;
ret = select (0, NULL, NULL, NULL, &timeout);
if (ret < 0) printf ("select failed, error = %d\n", WSAGetLastError());
if (!QueryPerformanceCounter (&after))
printf ("QueryPerformanceCounter failed\n");
printf ("time slept: %g s\n", (double) (after.QuadPart - before.QuadPart) /
(double) pcfreq.QuadPart);
return 0;
}
===============================================================================
produces the output
$ ./usleep.exe 6000
select failed, error = 10093
time slept: 6.87238e-005 s
Error 10093 is WSANOTINITIALISED.
3) Use of select without a socket descriptor, just a timeout, fails.
Witness: This program
===============================================================================
#include <winsock2.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
int main (int argc, char *argv[])
{
int usecs = atoi (argv[1]);
LARGE_INTEGER pcfreq;
WSADATA data;
LARGE_INTEGER before, after;
struct timeval timeout;
int ret;
if (!QueryPerformanceFrequency (&pcfreq))
printf ("QueryPerformanceFrequency failed\n");
WSAStartup (0x201, &data);
if (!QueryPerformanceCounter (&before))
printf ("QueryPerformanceCounter failed\n");
timeout.tv_sec = usecs / 1000000;
timeout.tv_usec = usecs % 1000000;
ret = select (0, NULL, NULL, NULL, &timeout);
if (ret < 0) printf ("select failed, error = %d\n", WSAGetLastError());
if (!QueryPerformanceCounter (&after))
printf ("QueryPerformanceCounter failed\n");
printf ("time slept: %g s\n", (double) (after.QuadPart - before.QuadPart) /
(double) pcfreq.QuadPart);
return 0;
}
===============================================================================
produces the output
$ ./usleep.exe 6000
select failed, error = 10022
time slept: 0.000258971 s
Error 10022 is WSAEINVAL.
4) select sleeps for at least 6 ms.
Witness: This program
===============================================================================
#include <winsock2.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
int main (int argc, char *argv[])
{
int usecs = atoi (argv[1]);
LARGE_INTEGER pcfreq;
WSADATA data;
SOCKET s;
fd_set dummy;
LARGE_INTEGER before, after;
struct timeval timeout;
int ret;
if (!QueryPerformanceFrequency (&pcfreq))
printf ("QueryPerformanceFrequency failed\n");
WSAStartup (0x201, &data);
s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
FD_ZERO(&dummy);
FD_SET(s, &dummy);
if (!QueryPerformanceCounter (&before))
printf ("QueryPerformanceCounter failed\n");
timeout.tv_sec = usecs / 1000000;
timeout.tv_usec = usecs % 1000000;
ret = select (0, NULL, NULL, &dummy, &timeout);
if (ret < 0) printf ("select failed, error = %d\n", WSAGetLastError());
if (!QueryPerformanceCounter (&after))
printf ("QueryPerformanceCounter failed\n");
printf ("time slept: %g s\n", (double) (after.QuadPart - before.QuadPart) /
(double) pcfreq.QuadPart);
return 0;
}
===============================================================================
when run on Windows XP, produces output like this:
$ ./usleep.exe 1000
time slept: 0.00615274 s
$ ./usleep.exe 2000
time slept: 0.00684696 s
$ ./usleep.exe 3000
time slept: 0.0065919 s
$ ./usleep.exe 4000
time slept: 0.00648378 s
$ ./usleep.exe 50000
time slept: 0.0564223 s
$ ./usleep.exe 51000
time slept: 0.0532749 s
$ ./usleep.exe 52000
time slept: 0.0534506 s
$ ./usleep.exe 53000
time slept: 0.0531825 s
$ ./usleep.exe 54000
time slept: 0.0532327 s
5) The Win32 Sleep function sleeps for at least 5 ms. (But at least it does not
need prior initialization and a socket for doing this :-)).
This program
===============================================================================
#include <winsock2.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
int main (int argc, char *argv[])
{
int usecs = atoi (argv[1]);
LARGE_INTEGER pcfreq;
LARGE_INTEGER before, after;
if (!QueryPerformanceFrequency (&pcfreq))
printf ("QueryPerformanceFrequency failed\n");
if (!QueryPerformanceCounter (&before))
printf ("QueryPerformanceCounter failed\n");
Sleep (usecs / 1000);
if (!QueryPerformanceCounter (&after))
printf ("QueryPerformanceCounter failed\n");
printf ("time slept: %g s\n", (double) (after.QuadPart - before.QuadPart) /
(double) pcfreq.QuadPart);
return 0;
}
===============================================================================
outputs:
$ ./usleep.exe 1000
time slept: 0.0116696 s
$ ./usleep.exe 2000
time slept: 0.00430949 s
$ ./usleep.exe 1000
time slept: 0.00483553 s
$ ./usleep.exe 2000
time slept: 0.00500846 s
$ ./usleep.exe 3000
time slept: 0.0048143 s
$ ./usleep.exe 4000
time slept: 0.0047696 s
$ ./usleep.exe 5000
time slept: 0.0050146 s
$ ./usleep.exe 6000
time slept: 0.00530682 s
$ ./usleep.exe 7000
time slept: 0.0048752 s
And it also has only about a 15 ms resolution:
$ ./usleep.exe 60000
time slept: 0.0512395 s
$ ./usleep.exe 61000
time slept: 0.0520256 s
$ ./usleep.exe 62000
time slept: 0.0518923 s
$ ./usleep.exe 63000
time slept: 0.0674114 s
$ ./usleep.exe 64000
time slept: 0.0694077 s
A combination of Sleep and busy-looping appears to give good results.
===============================================================================
#include <winsock2.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
struct timespec
{
time_t tv_sec;
long int tv_nsec;
};
static void
nanosleep (const struct timespec *requested_delay)
{
if (requested_delay->tv_sec > 0)
/* At least one second. Millisecond resolution is sufficient. */
Sleep (requested_delay->tv_sec * 1000 + requested_delay->tv_nsec / 1000000);
else
{
/* Use Sleep for the largest part, and busy-loop for the rest. */
static double frequency;
if (frequency == 0)
{
LARGE_INTEGER freq;
if (!QueryPerformanceFrequency (&freq))
{
/* Cannot use QueryPerformanceCounter. */
Sleep (requested_delay->tv_nsec / 1000000);
return;
}
frequency = (double) freq.QuadPart / 1000000000.0;
}
long long expected_counter_difference = requested_delay->tv_nsec *
frequency;
int sleep_part = (int) requested_delay->tv_nsec / 1000000 - 10;
LARGE_INTEGER before;
QueryPerformanceCounter (&before);
long long expected_counter = before.QuadPart +
expected_counter_difference;
if (sleep_part > 0)
Sleep (sleep_part);
for (;;)
{
LARGE_INTEGER after;
QueryPerformanceCounter (&after);
if (after.QuadPart >= expected_counter)
break;
}
}
}
int main (int argc, char *argv[])
{
int usecs = atoi (argv[1]);
LARGE_INTEGER pcfreq;
LARGE_INTEGER before, after;
if (!QueryPerformanceFrequency (&pcfreq))
printf ("QueryPerformanceFrequency failed\n");
if (!QueryPerformanceCounter (&before))
printf ("QueryPerformanceCounter failed\n");
struct timespec t;
t.tv_sec = usecs / 1000000;
t.tv_nsec = (usecs % 1000000) * 1000;
nanosleep (&t);
if (!QueryPerformanceCounter (&after))
printf ("QueryPerformanceCounter failed\n");
printf ("time slept: %g s\n", (double) (after.QuadPart - before.QuadPart) /
(double) pcfreq.QuadPart);
return 0;
}
===============================================================================
$ ./usleep.exe 699000
time slept: 0.699015 s
$ ./usleep.exe 699000
time slept: 0.699013 s
$ ./usleep.exe 700000
time slept: 0.700014 s
$ ./usleep.exe 701000
time slept: 0.701013 s
$ ./usleep.exe 4100
time slept: 0.00411449 s
$ ./usleep.exe 1300
time slept: 0.00131469 s
$ ./usleep.exe 1200
time slept: 0.001213 s
$ ./usleep.exe 100
time slept: 0.000112864 s
$ ./usleep.exe 90
time slept: 0.000104203 s
$ ./usleep.exe 10
time slept: 2.45841e-005 s
(Apparently there is an offset of 13 to 14 microseconds, but this is likely
CPU speed dependent.)
So here is a proposed patch for implementing a Woe32 nanosleep with a
resolution of ca. 10 microseconds or higher.
2010-04-04 Bruno Haible <br...@clisp.org>
Implement nanosleep for native Windows.
* lib/nanosleep.c (nanosleep): New implementation for native Windows.
--- lib/nanosleep.c.orig Sun Apr 4 14:45:40 2010
+++ lib/nanosleep.c Sun Apr 4 14:43:28 2010
@@ -15,7 +15,8 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
-/* written by Jim Meyering */
+/* written by Jim Meyering
+ and Bruno Haible for the Woe32 part */
#include <config.h>
@@ -83,7 +84,102 @@
return nanosleep (&intermediate, remaining_delay);
}
+#elif (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* Windows platforms. */
+
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+/* The Win32 function Sleep() has a resolution of about 15 ms and takes
+ at least 5 ms to execute. We use this function for longer time periods.
+ Additionally, we use busy-looping over short time periods, to get a
+ resolution of about 0.01 ms. In order to measure such short timespans,
+ we use the QueryPerformanceCounter() function. */
+
+int
+nanosleep (const struct timespec *requested_delay,
+ struct timespec *remaining_delay)
+{
+ static bool initialized;
+ /* Number of performance counter increments per nanosecond,
+ or zero if it could not be determined. */
+ static double ticks_per_nanosecond;
+
+ if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* For requested delays of one second or more, 15ms resolution is
+ sufficient. */
+ if (requested_delay->tv_sec == 0)
+ {
+ if (!initialized)
+ {
+ /* Initialize ticks_per_nanosecond. */
+ LARGE_INTEGER ticks_per_second;
+
+ if (QueryPerformanceFrequency (&ticks_per_second))
+ ticks_per_nanosecond =
+ (double) ticks_per_second.QuadPart / 1000000000.0;
+
+ initialized = true;
+ }
+ if (ticks_per_nanosecond)
+ {
+ /* QueryPerformanceFrequency worked. We can use
+ QueryPerformanceCounter. Use a combination of Sleep and
+ busy-looping. */
+ /* Number of milliseconds to pass to the Sleep function.
+ Since Sleep can take up to 8 ms less or 8 ms more than requested
+ (or maybe more if the system is loaded), we subtract 10 ms. */
+ int sleep_millis = (int) requested_delay->tv_nsec / 1000000 - 10;
+ /* Determine how many ticks to delay. */
+ LONGLONG wait_ticks = requested_delay->tv_nsec *
ticks_per_nanosecond;
+ /* Start. */
+ LARGE_INTEGER counter_before;
+ if (QueryPerformanceCounter (&counter_before))
+ {
+ /* Wait until the performance counter has reached this value.
+ We don't need to worry about overflow, because the performance
+ counter is reset at reboot, and with a frequency of 3.6E6
+ ticks per second 63 bits suffice for over 80000 years. */
+ LONGLONG wait_until = counter_before.QuadPart + wait_ticks;
+ /* Use Sleep for the longest part. */
+ if (sleep_millis > 0)
+ Sleep (sleep_millis);
+ /* Busy-loop for the rest. */
+ for (;;)
+ {
+ LARGE_INTEGER counter_after;
+ if (!QueryPerformanceCounter (&counter_after))
+ /* QueryPerformanceCounter failed, but succeeded earlier.
+ Should not happen. */
+ break;
+ if (counter_after.QuadPart >= wait_until)
+ /* The requested time has elapsed. */
+ break;
+ }
+ goto done;
+ }
+ }
+ }
+ /* Implementation for long delays and as fallback. */
+ Sleep (requested_delay->tv_sec * 1000 + requested_delay->tv_nsec / 1000000);
+
+ done:
+ /* Sleep is not interruptible. So there is no remaining delay. */
+ if (remaining_delay != NULL)
+ {
+ remaining_delay->tv_sec = 0;
+ remaining_delay->tv_nsec = 0;
+ }
+ return 0;
+}
+
#else
+/* Unix platforms lacking nanosleep. */
/* Some systems (MSDOS) don't have SIGCONT.
Using SIGTERM here turns the signal-handling code below
