git/commit-graph.h, branch v2.22.0-rc2

commit-graph write: don't die if the existing graph is corrupt

2019-04-01T03:14:50Z

When the commit-graph is written we end up calling parse_commit(). This will in turn invoke code that'll consult the existing commit-graph about the commit, if the graph is corrupted we die. We thus get into a state where a failing "commit-graph verify" can't be followed-up with a "commit-graph write" if core.commitGraph=true is set, the graph either needs to be manually removed to proceed, or core.commitGraph needs to be set to "false". Change the "commit-graph write" codepath to use a new parse_commit_no_graph() helper instead of parse_commit() to avoid this. The latter will call repo_parse_commit_internal() with use_commit_graph=1 as seen in 177722b344 ("commit: integrate commit graph with commit parsing", 2018-04-10). Not using the old graph at all slows down the writing of the new graph by some small amount, but is a sensible way to prevent an error in the existing commit-graph from spreading. Just fixing the current issue would be likely to result in code that's inadvertently broken in the future. New code might use the commit-graph at a distance. To detect such cases introduce a "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD" setting used when we do our corruption tests, and test that a "write/verify" combo works after every one of our current test cases where we now detect commit-graph corruption. Some of the code changes here might be strictly unnecessary, e.g. I was unable to find cases where the parse_commit() called from write_graph_chunk_data() didn't exit early due to "item->object.parsed" being true in repo_parse_commit_internal() (before the use_commit_graph=1 has any effect). But let's also convert those cases for good measure, we do not have exhaustive tests for all possible types of commit-graph corruption. This might need to be re-visited if we learn to write the commit-graph incrementally, but probably not. Hopefully we'll just start by finding out what commits we have in total, then read the old graph(s) to see what they cover, and finally write a new graph file with everything that's missing. In that case the new graph writing code just needs to continue to use e.g. a parse_commit() that doesn't consult the existing commit-graphs. Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Junio C Hamano

commit-graph: don't pass filename to load_commit_graph_one_fd_st()

2019-04-01T03:14:50Z

An earlier change implemented load_commit_graph_one_fd_st() in a way that was bug-compatible with earlier code in terms of the "graph file %s is too small" error message printing out the path to the commit-graph (".git/objects/info/commit-graph"). But change that, because: * A function that takes an already-open file descriptor also needing the filename isn't very intuitive. * The vast majority of errors we might emit when loading the graph come from parse_commit_graph(), which doesn't report the filename. Let's not do that either in this case for consistency. Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Junio C Hamano

commit-graph: don't early exit(1) on e.g. "git status"

2019-04-01T03:14:50Z

Make the commit-graph loading code work as a library that returns an error code instead of calling exit(1) when the commit-graph is corrupt. This means that e.g. "status" will now report commit-graph corruption as an "error: [...]" at the top of its output, but then proceed to work normally. This required splitting up the load_commit_graph_one() function so that the code that deals with open()-ing and stat()-ing the graph can now be called independently as open_commit_graph(). This is needed because "commit-graph verify" where the graph doesn't exist isn't an error. See the third paragraph in 283e68c72f ("commit-graph: add 'verify' subcommand", 2018-06-27). There's a bug in that logic where we conflate the intended ENOENT with other errno values (e.g. EACCES), but this change doesn't address that. That'll be addressed in a follow-up change. I'm then splitting most of the logic out of load_commit_graph_one() into load_commit_graph_one_fd_st(), which allows for providing an existing file descriptor and stat information to the loading code. This isn't strictly needed, but it would be redundant and confusing to open() and stat() the file twice for some of the codepaths, this allows for calling open_commit_graph() followed by load_commit_graph_one_fd_st(). The "graph_file" still needs to be passed to that function for the the "graph file %s is too small" error message. This leaves load_commit_graph_one() unused by everything except the internal prepare_commit_graph_one() function, so let's mark it as "static". If someone needs it in the future we can remove the "static" attribute. I could also rewrite its sole remaining user ("prepare_commit_graph_one()") to use load_commit_graph_one_fd_st() instead, but let's leave it at this. Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Ramsay Jones Signed-off-by: Junio C Hamano

Merge branch 'ab/commit-graph-write-progress'

2019-02-05T22:26:14Z

The codepath to show progress meter while writing out commit-graph file has been improved. * ab/commit-graph-write-progress: commit-graph write: emit a percentage for all progress commit-graph write: add itermediate progress commit-graph write: remove empty line for readability commit-graph write: add more descriptive progress output commit-graph write: show progress for object search commit-graph write: more descriptive "writing out" output commit-graph write: add "Writing out" progress output commit-graph: don't call write_graph_chunk_extra_edges() unnecessarily commit-graph: rename "large edges" to "extra edges"

commit-graph: rename "large edges" to "extra edges"

2019-01-22T19:33:46Z

The optional 'Large Edge List' chunk of the commit graph file stores parent information for commits with more than two parents, and the names of most of the macros, variables, struct fields, and functions related to this chunk contain the term "large edges", e.g. write_graph_chunk_large_edges(). However, it's not a really great term, as the edges to the second and subsequent parents stored in this chunk are not any larger than the edges to the first and second parents stored in the "main" 'Commit Data' chunk. It's the number of edges, IOW number of parents, that is larger compared to non-merge and "regular" two-parent merge commits. And indeed, two functions in 'commit-graph.c' have a local variable called 'num_extra_edges' that refer to the same thing, and this "extra edges" term is much better at describing these edges. So let's rename all these references to "large edges" in macro, variable, function, etc. names to "extra edges". There is a GRAPH_OCTOPUS_EDGES_NEEDED macro as well; for the sake of consistency rename it to GRAPH_EXTRA_EDGES_NEEDED. We can do so safely without causing any incompatibility issues, because the term "large edges" doesn't come up in the file format itself in any form (the chunk's magic is {'E', 'D', 'G', 'E'}, there is no 'L' in there), but only in the specification text. The string "large edges", however, does come up in the output of 'git commit-graph read' and in tests looking at its input, but that command is explicitly documented as debugging aid, so we can change its output and the affected tests safely. Signed-off-by: SZEDER Gábor Signed-off-by: Junio C Hamano

commit-graph, fuzz: add fuzzer for commit-graph

2019-01-16T04:31:49Z

Break load_commit_graph_one() into a new function, parse_commit_graph(). The latter function operates on arbitrary buffers, which makes it suitable as a fuzzing target. Since parse_commit_graph() is only called by load_commit_graph_one() (and the fuzzer described below), we omit error messages that would be duplicated by the caller. Adds fuzz-commit-graph.c, which provides a fuzzing entry point compatible with libFuzzer (and possibly other fuzzing engines). Signed-off-by: Josh Steadmon Signed-off-by: Junio C Hamano

Merge branch 'ds/commit-graph-with-grafts'

2018-10-16T07:15:59Z

The recently introduced commit-graph auxiliary data is incompatible with mechanisms such as replace & grafts that "breaks" immutable nature of the object reference relationship. Disable optimizations based on its use (and updating existing commit-graph) when these incompatible features are in use in the repository. * ds/commit-graph-with-grafts: commit-graph: close_commit_graph before shallow walk commit-graph: not compatible with uninitialized repo commit-graph: not compatible with grafts commit-graph: not compatible with replace objects test-repository: properly init repo commit-graph: update design document refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn callback refs.c: migrate internal ref iteration to pass thru repository argument

Merge branch 'ab/commit-graph-progress'

2018-10-16T07:15:58Z

Generation of (experimental) commit-graph files have so far been fairly silent, even though it takes noticeable amount of time in a meaningfully large repository. The users will now see progress output. * ab/commit-graph-progress: gc: fix regression in 7b0f229222 impacting --quiet commit-graph verify: add progress output commit-graph write: add progress output

Merge branch 'ds/commit-graph-tests'

2018-09-17T20:53:58Z

We can now optionally run tests with commit-graph enabled. * ds/commit-graph-tests: commit-graph: define GIT_TEST_COMMIT_GRAPH

Merge branch 'ds/reachable'

2018-09-17T20:53:52Z

The code for computing history reachability has been shuffled, obtained a bunch of new tests to cover them, and then being improved. * ds/reachable: commit-reach: correct accidental #include of C file commit-reach: use can_all_from_reach commit-reach: make can_all_from_reach... linear commit-reach: replace ref_newer logic test-reach: test commit_contains test-reach: test can_all_from_reach_with_flags test-reach: test reduce_heads test-reach: test get_merge_bases_many test-reach: test is_descendant_of test-reach: test in_merge_bases test-reach: create new test tool for ref_newer commit-reach: move can_all_from_reach_with_flags upload-pack: generalize commit date cutoff upload-pack: refactor ok_to_give_up() upload-pack: make reachable() more generic commit-reach: move commit_contains from ref-filter commit-reach: move ref_newer from remote.c commit.h: remove method declarations commit-reach: move walk methods from commit.c