From: Neal Becker (ndbecker2_at_gmail.com)
Date: Sun Jul 29 2007 - 11:14:18 PDT
Based on studying the code in cr_checkpoint.c, I have come up with the
following. Any comments appreciated. I'm guessing that the call to
cr_request_checkpoint, followed by the cr_poll_checkpoint, will efficiently
do the checkpoint and then wait for it to complete (but not necessarily be
flushed to the disk).
static void doit () {
int newfd = creat (newname.c_str(), 0600);
if (newfd < 0)
die ("creat failed");
cr_args.cr_fd = newfd;
cr_args.cr_scope = ...
cr_checkpoint_handle_t cr_handle;
int err = cr_request_checkpoint (&cr_args, &cr_handle);
if (err < 0)
die ("cr_request_checkpoint failed");
do {
int err = cr_poll_checkpoint (&cr_handle, NULL);
if (err < 0) {
if (errno == EINVAL) {
return; // restarted
}
else if (errno == EINTR) {
;
}
else {
perror ("cr_poll_checkpoint");
break;
}
}
else if (err == 0) {
die ("cr_poll_checkpoint returned unexepected 0");
}
} while (err < 0);
if (err == -1) {
die (std::string ("cr_poll_checkpoint") + strerror (err));
}
else if (err == -2) {
if (err == CR_ETEMPFAIL) {
die("Checkpoint cancelled by application: try again later\n");
} else if (err == ESRCH) {
die("Checkpoint failed: no processes checkpointed\n");
} else if (err == CR_EPERMFAIL) {
die("Checkpoint cancelled by application: unable to checkpoint\n");
} else if (err == CR_ENOSUPPORT) {
die("Checkpoint failed: support missing from application\n");
} else {
die(std::string ("ioctl") + strerror (err));
}
}
else if (err < 0) {
die(std::string ("cr_poll_checkpoint") + strerror (err));
}
if (rename (newname.c_str(), name.c_str()) != 0)
die ("rename failed");
}