Hi,
In http://sources.redhat.com/ml/cygwin/2002-09/msg01155.html, I noted that
the often-observed hangs of rsync under Cygwin were assuaged by a call to
msleep().
After upgrading my Cygwin environment to rsync 2.5.6, I'm seeing these
hangs again, not surprisingly given a CVS entry for main.c notes that
this kludge was not harmless:
Revision 1.162 / (download) - annotate - [select for diffs] ,
Tue Jan 28 05:05:53 2003 UTC (4 months, 4 weeks ago) by dwd
Remove the Cygwin msleep(100) before the generator kills the receiver,
because it caused the testsuite/unsafe-links test to hang.
So it seems sensible to attempt something a bit more elegant.
And the first question is why kill/signals are being used
being used here at all.
The illustrative patch below I think effects an equivalent synchronization,
but does so by queuing a byte into a pipe rather than sending a signal.
Of course, since it's not currently done this way, I may be overlooking
something obvious. I can't quite see what though, since in the event
that an error occurs then exit_cleanup is available to send SIGUSR1
with extreme prejudice; but if the protocol in fact concludes cleanly
then there really should be no need for an asynchronous notification?
Comments sought, meanwhile I'll test the patch a bit...
Regards
Anthony
*** main.c.Orig Fri Jun 27 15:21:22 2003
--- main.c Fri Jun 27 15:30:09 2003
***************
*** 390,395 ****
--- 390,396 ----
int status=0;
int recv_pipe[2];
int error_pipe[2];
+ int cleanup_pipe[2];
extern int preserve_hard_links;
extern int delete_after;
extern int recurse;
***************
*** 416,426 ****
--- 417,435 ----
exit_cleanup(RERR_SOCKETIO);
}
+ if (pipe(cleanup_pipe) < 0) {
+ rprintf(FERROR,"cleanup pipe failed in do_recv\n");
+ exit_cleanup(RERR_SOCKETIO);
+ }
+
io_flush();
if ((pid=do_fork()) == 0) {
+ char tmp;
+
close(recv_pipe[0]);
close(error_pipe[0]);
+ close(cleanup_pipe[1]);
if (f_in != f_out) close(f_out);
/* we can't let two processes write to the socket at one time */
***************
*** 436,450 ****
write_int(recv_pipe[1],1);
close(recv_pipe[1]);
io_flush();
! /* finally we go to sleep until our parent kills us
! with a USR2 signal. We sleep for a short time as on
! some OSes a signal won't interrupt a sleep! */
! while (msleep(20))
! ;
}
close(recv_pipe[1]);
close(error_pipe[1]);
if (f_in != f_out) close(f_in);
io_start_buffering(f_out);
--- 445,465 ----
write_int(recv_pipe[1],1);
close(recv_pipe[1]);
io_flush();
! do {
! status = read(cleanup_pipe[0], &tmp, 1);
! } while (status == -1 && errno == EINTR);
! if (status != 1) {
! rprintf(FERROR,"cleanup read returned %d in do_recv\n",
status);
! if (status == -1)
! rprintf(FERROR,"with errno %d (%s)\n", errno,
strerror(errno));
! _exit(RERR_PARTIAL);
! }
! _exit(0);
}
close(recv_pipe[1]);
close(error_pipe[1]);
+ close(cleanup_pipe[0]);
if (f_in != f_out) close(f_in);
io_start_buffering(f_out);
***************
*** 462,469 ****
io_flush();
io_set_error_fd(-1);
! kill(pid, SIGUSR2);
! wait_process(pid, &status);
return status;
}
--- 477,487 ----
io_flush();
io_set_error_fd(-1);
! write(cleanup_pipe[1], ".", 1);
! if (waitpid(pid, &status, 0) != pid) {
! rprintf(FERROR,"cleanup in do_recv failed\n");
! exit_cleanup(RERR_SOCKETIO);
! }
return status;
}
***************
*** 867,878 ****
exit_cleanup(RERR_SIGNAL);
}
- static RETSIGTYPE sigusr2_handler(int UNUSED(val)) {
- extern int log_got_error;
- if (log_got_error) _exit(RERR_PARTIAL);
- _exit(0);
- }
-
static RETSIGTYPE sigchld_handler(int UNUSED(val)) {
#ifdef WNOHANG
int cnt, status;
--- 885,890 ----
***************
*** 964,970 ****
orig_argv = argv;
signal(SIGUSR1, sigusr1_handler);
- signal(SIGUSR2, sigusr2_handler);
signal(SIGCHLD, sigchld_handler);
#ifdef MAINTAINER_MODE
signal(SIGSEGV, rsync_panic_handler);
--- 976,981 ----
--
Anthony Heading
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