git/pack-write.c, branch v2.35.2

Merge branch 'tb/pack-finalize-ordering'

2021-09-20T22:20:42Z

The order in which various files that make up a single (conceptual) packfile has been reevaluated and straightened up. This matters in correctness, as an incomplete set of files must not be shown to a running Git. * tb/pack-finalize-ordering: pack-objects: rename .idx files into place after .bitmap files pack-write: split up finish_tmp_packfile() function builtin/index-pack.c: move `.idx` files into place last index-pack: refactor renaming in final() builtin/repack.c: move `.idx` files into place last pack-write.c: rename `.idx` files after `*.rev` pack-write: refactor renaming in finish_tmp_packfile() bulk-checkin.c: store checksum directly pack.h: line-wrap the definition of finish_tmp_packfile()

Merge branch 'ab/reverse-midx-optim'

2021-09-15T20:15:27Z

The code that optionally creates the *.rev reverse index file has been optimized to avoid needless computation when it is not writing the file out. * ab/reverse-midx-optim: pack-write: skip *.rev work when not writing *.rev

pack-write: split up finish_tmp_packfile() function

2021-09-10T01:23:11Z

Split up the finish_tmp_packfile() function and use the split-up version in pack-objects.c in preparation for moving the step of renaming the *.idx file later as part of a function change. Since the only other caller of finish_tmp_packfile() was in bulk-checkin.c, and it won't be needing a change to its *.idx renaming, provide a thin wrapper for the old function as a static function in that file. If other callers end up needing the simpler version it could be moved back to "pack-write.c" and "pack.h". Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-write.c: rename `.idx` files after `*.rev`

2021-09-10T01:23:11Z

We treat the presence of an `.idx` file as the indicator of whether or not it's safe to use a packfile. But `finish_tmp_packfile()` (which is responsible for writing the pack and moving the temporary versions of all of its auxiliary files into place) is inconsistent about the write order. Specifically, it moves the `.rev` file into place after the `.idx`, leaving open the possibility to open a pack which looks "ready" (because the `.idx` file exists and is readable) but appears momentarily to not have a `.rev` file. This causes Git to fall back to generating the pack's reverse index in memory. Though racy, this amounts to an unnecessary slow-down at worst, and doesn't affect the correctness of the resulting reverse index. Close this race by moving the .rev file into place before moving the .idx file into place. This still leaves the issue of `.idx` files being renamed into place before the auxiliary `.bitmap` file is renamed when in pack-object.c's write_pack_file() "write_bitmap_index" is true. That race will be addressed in subsequent commits. Signed-off-by: Taylor Blau Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-write: refactor renaming in finish_tmp_packfile()

2021-09-10T01:23:11Z

Refactor the renaming in finish_tmp_packfile() into a helper function. The callers are now expected to pass a "name_buffer" ending in "pack-OID." instead of the previous "pack-", we then append "pack", "idx" or "rev" to it. By doing the strbuf_setlen() in rename_tmp_packfile() we reuse the buffer and avoid the repeated allocations we'd get if that function had its own temporary "struct strbuf". This approach of reusing the buffer does make the last user in pack-object.c's write_pack_file() slightly awkward, since we needlessly do a strbuf_setlen() before calling strbuf_release() for consistency. In subsequent changes we'll move that bitmap writing code around, so let's not skip the strbuf_setlen() now. The previous strbuf_reset() idiom originated with 5889271114a (finish_tmp_packfile():use strbuf for pathname construction, 2014-03-03), which in turn was a minimal adjustment of pre-strbuf code added in 0e990530ae (finish_tmp_packfile(): a helper function, 2011-10-28). Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-write: skip .rev work when not writing .rev

2021-09-08T05:04:03Z

Fix a performance regression introduced in a587b5a786 (pack-write.c: extract 'write_rev_file_order', 2021-03-30) and stop needlessly allocating the "pack_order" array and sorting it with "pack_order_cmp()", only to throw that work away when we discover that we're not writing *.rev files after all. This redundant work was not present in the original version of this code added in 8ef50d9958 (pack-write.c: prepare to write 'pack-*.rev' files, 2021-01-25). There we'd call write_rev_file() from e.g. finish_tmp_packfile(), but we'd "return NULL" early in write_rev_file() if not doing a "WRITE_REV" or "WRITE_REV_VERIFY". Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Junio C Hamano

use xopen() to handle fatal open(2) failures

2021-08-25T21:39:08Z

Add and apply a semantic patch for using xopen() instead of calling open(2) and die() or die_errno() explicitly. This makes the error messages more consistent and shortens the code. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

Merge branch 'tb/reverse-midx'

2021-04-08T20:23:25Z

An on-disk reverse-index to map the in-pack location of an object back to its object name across multiple packfiles is introduced. * tb/reverse-midx: midx.c: improve cache locality in midx_pack_order_cmp() pack-revindex: write multi-pack reverse indexes pack-write.c: extract 'write_rev_file_order' pack-revindex: read multi-pack reverse indexes Documentation/technical: describe multi-pack reverse indexes midx: make some functions non-static midx: keep track of the checksum midx: don't free midx_name early midx: allow marking a pack as preferred t/helper/test-read-midx.c: add '--show-objects' builtin/multi-pack-index.c: display usage on unrecognized command builtin/multi-pack-index.c: don't enter bogus cmd_mode builtin/multi-pack-index.c: split sub-commands builtin/multi-pack-index.c: define common usage with a macro builtin/multi-pack-index.c: don't handle 'progress' separately builtin/multi-pack-index.c: inline 'flags' with options

pack-write.c: extract 'write_rev_file_order'

2021-04-01T20:07:37Z

Existing callers provide the reverse index code with an array of 'struct pack_idx_entry *'s, which is then sorted by pack order (comparing the offsets of each object within the pack). Prepare for the multi-pack index to write a .rev file by providing a way to write the reverse index without an array of pack_idx_entry (which the MIDX code does not have). Instead, callers can invoke 'write_rev_index_positions()', which takes an array of uint32_t's. The ith entry in this array specifies the ith object's (in index order) position within the pack (in pack order). Expose this new function for use in a later patch, and rewrite the existing write_rev_file() in terms of this new function. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

Merge branch 'jt/transfer-fsck-across-packs'

2021-03-01T22:02:57Z

The approach to "fsck" the incoming objects in "index-pack" is attractive for performance reasons (we have them already in core, inflated and ready to be inspected), but fundamentally cannot be applied fully when we receive more than one pack stream, as a tree object in one pack may refer to a blob object in another pack as ".gitmodules", when we want to inspect blobs that are used as ".gitmodules" file, for example. Teach "index-pack" to emit objects that must be inspected later and check them in the calling "fetch-pack" process. * jt/transfer-fsck-across-packs: fetch-pack: print and use dangling .gitmodules fetch-pack: with packfile URIs, use index-pack arg http-fetch: allow custom index-pack args http: allow custom index-pack args