git/packfile.c, branch v2.19.2

for_each_packed_object: support iterating in pack-order

2018-08-13T20:48:28Z

We currently iterate over objects within a pack in .idx order, which uses the object hashes. That means that it is effectively random with respect to the location of the object within the pack. If you're going to access the actual object data, there are two reasons to move linearly through the pack itself: 1. It improves the locality of access in the packfile. In the cold-cache case, this may mean fewer disk seeks, or better usage of disk cache. 2. We store related deltas together in the packfile. Which means that the delta base cache can operate much more efficiently if we visit all of those related deltas in sequence, as the earlier items are likely to still be in the cache. Whereas if we visit the objects in random order, our cache entries are much more likely to have been evicted by unrelated deltas in the meantime. So in general, if you're going to access the object contents pack order is generally going to end up more efficient. But if you're simply generating a list of object names, or if you're going to end up sorting the result anyway, you're better off just using the .idx order, as finding the pack order means generating the in-memory pack-revindex. According to the numbers in 8b8dfd5132 (pack-revindex: radix-sort the revindex, 2013-07-11), that takes about 200ms for linux.git, and 20ms for git.git (those numbers are a few years old but are still a good ballpark). That makes it a good optimization for some cases (we can save tens of seconds in git.git by having good locality of delta access, for a 20ms cost), but a bad one for others (e.g., right now "cat-file --batch-all-objects --batch-check="%(objectname)" is 170ms in git.git, so adding 20ms to that is noticeable). Hence this patch makes it an optional flag. You can't actually do any interesting timings yet, as it's not plumbed through to any user-facing tools like cat-file. That will come in a later patch. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

for_each_*_object: take flag arguments as enum

2018-08-13T20:48:25Z

It's not wrong to pass our flags in an "unsigned", as we know it will be at least as large as the enum. However, using the enum in the declaration makes it more obvious where to find the list of flags. While we're here, let's also drop the "extern" noise-words from the declarations, per our modern coding style. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

object: add repository argument to parse_object

2018-06-29T17:43:38Z

Add a repository argument to allow the callers of parse_object to be more specific about which repository to act on. This is a small mechanical change; it doesn't change the implementation to handle repositories other than the_repository yet. As with the previous commits, use a macro to catch callers passing a repository other than the_repository at compile time. Signed-off-by: Jonathan Nieder Signed-off-by: Stefan Beller Signed-off-by: Junio C Hamano

Merge branch 'jl/zlib-restore-nul-termination'

2018-06-18T17:18:43Z

Make zlib inflate codepath more robust against versions of zlib that clobber unused portion of outbuf. * jl/zlib-restore-nul-termination: packfile: correct zlib buffer handling

packfile: correct zlib buffer handling

2018-06-13T18:34:27Z

The buffer being passed to zlib includes a NUL terminator that git needs to keep in place. unpack_compressed_entry() attempts to detect the case that the source buffer hasn't been fully consumed by checking to see if the destination buffer has been over consumed. This causes a problem, that more recent zlib patches have been poisoning the unconsumed portions of the buffer which overwrites the NUL byte, while correctly returning length and status. Let's place the NUL at the end of the buffer after inflate returns to assure that it doesn't result in problems for git even if its been overwritten by zlib. Signed-off-by: Jeremy Linton Signed-off-by: Junio C Hamano

Merge branch 'bc/object-id'

2018-05-30T05:04:10Z

Conversion from uchar[20] to struct object_id continues. * bc/object-id: (42 commits) merge-one-file: compute empty blob object ID add--interactive: compute the empty tree value Update shell scripts to compute empty tree object ID sha1_file: only expose empty object constants through git_hash_algo dir: use the_hash_algo for empty blob object ID sequencer: use the_hash_algo for empty tree object ID cache-tree: use is_empty_tree_oid sha1_file: convert cached object code to struct object_id builtin/reset: convert use of EMPTY_TREE_SHA1_BIN builtin/receive-pack: convert one use of EMPTY_TREE_SHA1_HEX wt-status: convert two uses of EMPTY_TREE_SHA1_HEX submodule: convert several uses of EMPTY_TREE_SHA1_HEX sequencer: convert one use of EMPTY_TREE_SHA1_HEX merge: convert empty tree constant to the_hash_algo builtin/merge: switch tree functions to use object_id builtin/am: convert uses of EMPTY_TREE_SHA1_BIN to the_hash_algo sha1-file: add functions for hex empty tree and blob OIDs builtin/receive-pack: avoid hard-coded constants for push certs diff: specify abbreviation size in terms of the_hash_algo upload-pack: replace use of several hard-coded constants ...

Merge branch 'js/use-bug-macro'

2018-05-30T05:04:07Z

Developer support update, by using BUG() macro instead of die() to mark codepaths that should not happen more clearly. * js/use-bug-macro: BUG_exit_code: fix sparse "symbol not declared" warning Convert remaining die*(BUG) messages Replace all die("BUG: ...") calls by BUG() ones run-command: use BUG() to report bugs, not die() test-tool: help verifying BUG() code paths

Merge branch 'sb/oid-object-info'

2018-05-23T05:38:16Z

The codepath around object-info API has been taught to take the repository object (which in turn tells the API which object store the objects are to be located). * sb/oid-object-info: cache.h: allow oid_object_info to handle arbitrary repositories packfile: add repository argument to cache_or_unpack_entry packfile: add repository argument to unpack_entry packfile: add repository argument to read_object packfile: add repository argument to packed_object_info packfile: add repository argument to packed_to_object_type packfile: add repository argument to retry_bad_packed_offset cache.h: add repository argument to oid_object_info cache.h: add repository argument to oid_object_info_extended

Merge branch 'ds/lazy-load-trees'

2018-05-23T05:38:13Z

The code has been taught to use the duplicated information stored in the commit-graph file to learn the tree object name for a commit to avoid opening and parsing the commit object when it makes sense to do so. * ds/lazy-load-trees: coccinelle: avoid wrong transformation suggestions from commit.cocci commit-graph: lazy-load trees for commits treewide: replace maybe_tree with accessor methods commit: create get_commit_tree() method treewide: rename tree to maybe_tree

Merge branch 'ds/commit-graph'

2018-05-08T06:59:20Z

Precompute and store information necessary for ancestry traversal in a separate file to optimize graph walking. * ds/commit-graph: commit-graph: implement "--append" option commit-graph: build graph from starting commits commit-graph: read only from specific pack-indexes commit: integrate commit graph with commit parsing commit-graph: close under reachability commit-graph: add core.commitGraph setting commit-graph: implement git commit-graph read commit-graph: implement git-commit-graph write commit-graph: implement write_commit_graph() commit-graph: create git-commit-graph builtin graph: add commit graph design document commit-graph: add format document csum-file: refactor finalize_hashfile() method csum-file: rename hashclose() to finalize_hashfile()