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upload-pack: Use finish_{command,async}() instead of waitpid().

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upload-pack spawns two processes, rev-list and pack-objects, and carefully
monitors their status so that it can report failure to the remote end.
This change removes the complicated procedures on the grounds of the
following observations:

- If everything is OK, rev-list closes its output pipe end, upon which
  pack-objects (which reads from the pipe) sees EOF and terminates itself,
  closing its output (and error) pipes. upload-pack reads from both until
  it sees EOF in both. It collects the exit codes of the child processes
  (which indicate success) and terminates successfully.

- If rev-list sees an error, it closes its output and terminates with
  failure. pack-objects sees EOF in its input and terminates successfully.
  Again upload-pack reads its inputs until EOF. When it now collects
  the exit codes of its child processes, it notices the failure of rev-list
  and signals failure to the remote end.

- If pack-objects sees an error, it terminates with failure. Since this
  breaks the pipe to rev-list, rev-list is killed with SIGPIPE.
  upload-pack reads its input until EOF, then collects the exit codes of
  the child processes, notices their failures, and signals failure to the
  remote end.

- If upload-pack itself dies unexpectedly, pack-objects is killed with
  SIGPIPE, and subsequently also rev-list.

The upshot of this is that precise monitoring of child processes is not
required because both terminate if either one of them dies unexpectedly.
This allows us to use finish_command() and finish_async() instead of
an explicit waitpid(2) call.

The change is smaller than it looks because most of it only reduces the
indentation of a large part of the inner loop.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Sixt
2007-11-04 20:46:48 +01:00
committed by Junio C Hamano
parent fe61935007
commit 4c324c0050
2 changed files with 154 additions and 117 deletions
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196
upload-pack.c
View File

@ -144,6 +144,7 @@ static void create_pack_file(void)
char abort_msg[] = "aborting due to possible repository "
"corruption on the remote side.";
int buffered = -1;
ssize_t sz;
const char *argv[10];
int arg = 0;
@ -168,22 +169,15 @@ static void create_pack_file(void)
pack_objects.git_cmd = 1;
pack_objects.argv = argv;
if (start_command(&pack_objects)) {
/* daemon sets things up to ignore TERM */
kill(rev_list.pid, SIGKILL);
if (start_command(&pack_objects))
die("git-upload-pack: unable to fork git-pack-objects");
}
/* We read from pack_objects.err to capture stderr output for
* progress bar, and pack_objects.out to capture the pack data.
*/
while (1) {
const char *who;
struct pollfd pfd[2];
pid_t pid;
int status;
ssize_t sz;
int pe, pu, pollsize;
reset_timeout();
@ -204,123 +198,91 @@ static void create_pack_file(void)
pollsize++;
}
if (pollsize) {
if (poll(pfd, pollsize, -1) < 0) {
if (errno != EINTR) {
error("poll failed, resuming: %s",
strerror(errno));
sleep(1);
}
continue;
}
if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
/* Data ready; we keep the last byte
* to ourselves in case we detect
* broken rev-list, so that we can
* leave the stream corrupted. This
* is unfortunate -- unpack-objects
* would happily accept a valid pack
* data with trailing garbage, so
* appending garbage after we pass all
* the pack data is not good enough to
* signal breakage to downstream.
*/
char *cp = data;
ssize_t outsz = 0;
if (0 <= buffered) {
*cp++ = buffered;
outsz++;
}
sz = xread(pack_objects.out, cp,
sizeof(data) - outsz);
if (0 < sz)
;
else if (sz == 0) {
close(pack_objects.out);
pack_objects.out = -1;
}
else
goto fail;
sz += outsz;
if (1 < sz) {
buffered = data[sz-1] & 0xFF;
sz--;
}
else
buffered = -1;
sz = send_client_data(1, data, sz);
if (sz < 0)
goto fail;
}
if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
/* Status ready; we ship that in the side-band
* or dump to the standard error.
*/
sz = xread(pack_objects.err, progress,
sizeof(progress));
if (0 < sz)
send_client_data(2, progress, sz);
else if (sz == 0) {
close(pack_objects.err);
pack_objects.err = -1;
}
else
goto fail;
}
}
if (!pollsize)
break;
/* See if the children are still there */
if (rev_list.pid || pack_objects.pid) {
pid = waitpid(-1, &status, WNOHANG);
if (!pid)
continue;
who = ((pid == rev_list.pid) ? "git-rev-list" :
(pid == pack_objects.pid) ? "git-pack-objects" :
NULL);
if (!who) {
if (pid < 0) {
error("git-upload-pack: %s",
strerror(errno));
goto fail;
}
error("git-upload-pack: we weren't "
"waiting for %d", pid);
continue;
if (poll(pfd, pollsize, -1) < 0) {
if (errno != EINTR) {
error("poll failed, resuming: %s",
strerror(errno));
sleep(1);
}
if (!WIFEXITED(status) || WEXITSTATUS(status) > 0) {
error("git-upload-pack: %s died with error.",
who);
goto fail;
}
if (pid == rev_list.pid)
rev_list.pid = 0;
if (pid == pack_objects.pid)
pack_objects.pid = 0;
if (rev_list.pid || pack_objects.pid)
continue;
}
/* both died happily */
if (pollsize)
continue;
/* flush the data */
if (0 <= buffered) {
data[0] = buffered;
sz = send_client_data(1, data, 1);
}
if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
/* Data ready; we keep the last byte to ourselves
* in case we detect broken rev-list, so that we
* can leave the stream corrupted. This is
* unfortunate -- unpack-objects would happily
* accept a valid packdata with trailing garbage,
* so appending garbage after we pass all the
* pack data is not good enough to signal
* breakage to downstream.
*/
char *cp = data;
ssize_t outsz = 0;
if (0 <= buffered) {
*cp++ = buffered;
outsz++;
}
sz = xread(pack_objects.out, cp,
sizeof(data) - outsz);
if (0 < sz)
;
else if (sz == 0) {
close(pack_objects.out);
pack_objects.out = -1;
}
else
goto fail;
sz += outsz;
if (1 < sz) {
buffered = data[sz-1] & 0xFF;
sz--;
}
else
buffered = -1;
sz = send_client_data(1, data, sz);
if (sz < 0)
goto fail;
fprintf(stderr, "flushed.\n");
}
if (use_sideband)
packet_flush(1);
return;
if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
/* Status ready; we ship that in the side-band
* or dump to the standard error.
*/
sz = xread(pack_objects.err, progress,
sizeof(progress));
if (0 < sz)
send_client_data(2, progress, sz);
else if (sz == 0) {
close(pack_objects.err);
pack_objects.err = -1;
}
else
goto fail;
}
}
if (finish_command(&pack_objects)) {
error("git-upload-pack: git-pack-objects died with error.");
goto fail;
}
if (finish_async(&rev_list))
goto fail; /* error was already reported */
/* flush the data */
if (0 <= buffered) {
data[0] = buffered;
sz = send_client_data(1, data, 1);
if (sz < 0)
goto fail;
fprintf(stderr, "flushed.\n");
}
if (use_sideband)
packet_flush(1);
return;
fail:
if (pack_objects.pid)
kill(pack_objects.pid, SIGKILL);
if (rev_list.pid)
kill(rev_list.pid, SIGKILL);
send_client_data(3, abort_msg, sizeof(abort_msg));
die("git-upload-pack: %s", abort_msg);
}