Revision b81401c1de0e0fec39f8643ce7a794fda083f7a1 authored by Jeff King on 27 August 2012, 13:27:15 UTC, committed by Junio C Hamano on 27 August 2012, 17:49:09 UTC
All of the smart-http GET requests go through the http_get_* functions, which will prompt for credentials and retry if we see an HTTP 401. POST requests, however, do not go through any central point. Moreover, it is difficult to retry in the general case; we cannot assume the request body fits in memory or is even seekable, and we don't know how much of it was consumed during the attempt. Most of the time, this is not a big deal; for both fetching and pushing, we make a GET request before doing any POSTs, so typically we figure out the credentials during the first request, then reuse them during the POST. However, some servers may allow a client to get the list of refs from receive-pack without authentication, and then require authentication when the client actually tries to POST the pack. This is not ideal, as the client may do a non-trivial amount of work to generate the pack (e.g., delta-compressing objects). However, for a long time it has been the recommended example configuration in git-http-backend(1) for setting up a repository with anonymous fetch and authenticated push. This setup has always been broken without putting a username into the URL. Prior to commit 986bbc0, it did work with a username in the URL, because git would prompt for credentials before making any requests at all. However, post-986bbc0, it is totally broken. Since it has been advertised in the manpage for some time, we should make sure it works. Unfortunately, it is not as easy as simply calling post_rpc again when it fails, due to the input issue mentioned above. However, we can still make this specific case work by retrying in two specific instances: 1. If the request is large (bigger than LARGE_PACKET_MAX), we will first send a probe request with a single flush packet. Since this request is static, we can freely retry it. 2. If the request is small and we are not using gzip, then we have the whole thing in-core, and we can freely retry. That means we will not retry in some instances, including: 1. If we are using gzip. However, we only do so when calling git-upload-pack, so it does not apply to pushes. 2. If we have a large request, the probe succeeds, but then the real POST wants authentication. This is an extremely unlikely configuration and not worth worrying about. While it might be nice to cover those instances, doing so would be significantly more complex for very little real-world gain. In the long run, we will be much better off when curl learns to internally handle authentication as a callback, and we can cleanly handle all cases that way. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 8809703
diffcore-break.c
/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
static int should_break(struct diff_filespec *src,
struct diff_filespec *dst,
int break_score,
int *merge_score_p)
{
/* dst is recorded as a modification of src. Are they so
* different that we are better off recording this as a pair
* of delete and create?
*
* There are two criteria used in this algorithm. For the
* purposes of helping later rename/copy, we take both delete
* and insert into account and estimate the amount of "edit".
* If the edit is very large, we break this pair so that
* rename/copy can pick the pieces up to match with other
* files.
*
* On the other hand, we would want to ignore inserts for the
* pure "complete rewrite" detection. As long as most of the
* existing contents were removed from the file, it is a
* complete rewrite, and if sizable chunk from the original
* still remains in the result, it is not a rewrite. It does
* not matter how much or how little new material is added to
* the file.
*
* The score we leave for such a broken filepair uses the
* latter definition so that later clean-up stage can find the
* pieces that should not have been broken according to the
* latter definition after rename/copy runs, and merge the
* broken pair that have a score lower than given criteria
* back together. The break operation itself happens
* according to the former definition.
*
* The minimum_edit parameter tells us when to break (the
* amount of "edit" required for us to consider breaking the
* pair). We leave the amount of deletion in *merge_score_p
* when we return.
*
* The value we return is 1 if we want the pair to be broken,
* or 0 if we do not.
*/
unsigned long delta_size, max_size;
unsigned long src_copied, literal_added, src_removed;
*merge_score_p = 0; /* assume no deletion --- "do not break"
* is the default.
*/
if (S_ISREG(src->mode) != S_ISREG(dst->mode)) {
*merge_score_p = (int)MAX_SCORE;
return 1; /* even their types are different */
}
if (src->sha1_valid && dst->sha1_valid &&
!hashcmp(src->sha1, dst->sha1))
return 0; /* they are the same */
if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
return 0; /* error but caught downstream */
max_size = ((src->size > dst->size) ? src->size : dst->size);
if (max_size < MINIMUM_BREAK_SIZE)
return 0; /* we do not break too small filepair */
if (diffcore_count_changes(src, dst,
&src->cnt_data, &dst->cnt_data,
0,
&src_copied, &literal_added))
return 0;
/* sanity */
if (src->size < src_copied)
src_copied = src->size;
if (dst->size < literal_added + src_copied) {
if (src_copied < dst->size)
literal_added = dst->size - src_copied;
else
literal_added = 0;
}
src_removed = src->size - src_copied;
/* Compute merge-score, which is "how much is removed
* from the source material". The clean-up stage will
* merge the surviving pair together if the score is
* less than the minimum, after rename/copy runs.
*/
*merge_score_p = (int)(src_removed * MAX_SCORE / src->size);
if (*merge_score_p > break_score)
return 1;
/* Extent of damage, which counts both inserts and
* deletes.
*/
delta_size = src_removed + literal_added;
if (delta_size * MAX_SCORE / max_size < break_score)
return 0;
/* If you removed a lot without adding new material, that is
* not really a rewrite.
*/
if ((src->size * break_score < src_removed * MAX_SCORE) &&
(literal_added * 20 < src_removed) &&
(literal_added * 20 < src_copied))
return 0;
return 1;
}
void diffcore_break(int break_score)
{
struct diff_queue_struct *q = &diff_queued_diff;
struct diff_queue_struct outq;
/* When the filepair has this much edit (insert and delete),
* it is first considered to be a rewrite and broken into a
* create and delete filepair. This is to help breaking a
* file that had too much new stuff added, possibly from
* moving contents from another file, so that rename/copy can
* match it with the other file.
*
* int break_score; we reuse incoming parameter for this.
*/
/* After a pair is broken according to break_score and
* subjected to rename/copy, both of them may survive intact,
* due to lack of suitable rename/copy peer. Or, the caller
* may be calling us without using rename/copy. When that
* happens, we merge the broken pieces back into one
* modification together if the pair did not have more than
* this much delete. For this computation, we do not take
* insert into account at all. If you start from a 100-line
* file and delete 97 lines of it, it does not matter if you
* add 27 lines to it to make a new 30-line file or if you add
* 997 lines to it to make a 1000-line file. Either way what
* you did was a rewrite of 97%. On the other hand, if you
* delete 3 lines, keeping 97 lines intact, it does not matter
* if you add 3 lines to it to make a new 100-line file or if
* you add 903 lines to it to make a new 1000-line file.
* Either way you did a lot of additions and not a rewrite.
* This merge happens to catch the latter case. A merge_score
* of 80% would be a good default value (a broken pair that
* has score lower than merge_score will be merged back
* together).
*/
int merge_score;
int i;
/* See comment on DEFAULT_BREAK_SCORE and
* DEFAULT_MERGE_SCORE in diffcore.h
*/
merge_score = (break_score >> 16) & 0xFFFF;
break_score = (break_score & 0xFFFF);
if (!break_score)
break_score = DEFAULT_BREAK_SCORE;
if (!merge_score)
merge_score = DEFAULT_MERGE_SCORE;
DIFF_QUEUE_CLEAR(&outq);
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
int score;
/*
* We deal only with in-place edit of blobs.
* We do not break anything else.
*/
if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two) &&
object_type(p->one->mode) == OBJ_BLOB &&
object_type(p->two->mode) == OBJ_BLOB &&
!strcmp(p->one->path, p->two->path)) {
if (should_break(p->one, p->two,
break_score, &score)) {
/* Split this into delete and create */
struct diff_filespec *null_one, *null_two;
struct diff_filepair *dp;
/* Set score to 0 for the pair that
* needs to be merged back together
* should they survive rename/copy.
* Also we do not want to break very
* small files.
*/
if (score < merge_score)
score = 0;
/* deletion of one */
null_one = alloc_filespec(p->one->path);
dp = diff_queue(&outq, p->one, null_one);
dp->score = score;
dp->broken_pair = 1;
/* creation of two */
null_two = alloc_filespec(p->two->path);
dp = diff_queue(&outq, null_two, p->two);
dp->score = score;
dp->broken_pair = 1;
diff_free_filespec_blob(p->one);
diff_free_filespec_blob(p->two);
free(p); /* not diff_free_filepair(), we are
* reusing one and two here.
*/
continue;
}
}
diff_free_filespec_data(p->one);
diff_free_filespec_data(p->two);
diff_q(&outq, p);
}
free(q->queue);
*q = outq;
return;
}
static void merge_broken(struct diff_filepair *p,
struct diff_filepair *pp,
struct diff_queue_struct *outq)
{
/* p and pp are broken pairs we want to merge */
struct diff_filepair *c = p, *d = pp, *dp;
if (DIFF_FILE_VALID(p->one)) {
/* this must be a delete half */
d = p; c = pp;
}
/* Sanity check */
if (!DIFF_FILE_VALID(d->one))
die("internal error in merge #1");
if (DIFF_FILE_VALID(d->two))
die("internal error in merge #2");
if (DIFF_FILE_VALID(c->one))
die("internal error in merge #3");
if (!DIFF_FILE_VALID(c->two))
die("internal error in merge #4");
dp = diff_queue(outq, d->one, c->two);
dp->score = p->score;
diff_free_filespec_data(d->two);
diff_free_filespec_data(c->one);
free(d);
free(c);
}
void diffcore_merge_broken(void)
{
struct diff_queue_struct *q = &diff_queued_diff;
struct diff_queue_struct outq;
int i, j;
DIFF_QUEUE_CLEAR(&outq);
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
if (!p)
/* we already merged this with its peer */
continue;
else if (p->broken_pair &&
!strcmp(p->one->path, p->two->path)) {
/* If the peer also survived rename/copy, then
* we merge them back together.
*/
for (j = i + 1; j < q->nr; j++) {
struct diff_filepair *pp = q->queue[j];
if (pp->broken_pair &&
!strcmp(pp->one->path, pp->two->path) &&
!strcmp(p->one->path, pp->two->path)) {
/* Peer survived. Merge them */
merge_broken(p, pp, &outq);
q->queue[j] = NULL;
break;
}
}
if (q->nr <= j)
/* The peer did not survive, so we keep
* it in the output.
*/
diff_q(&outq, p);
}
else
diff_q(&outq, p);
}
free(q->queue);
*q = outq;
return;
}
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