kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Ævar Arnfjörð Bjarmason	43d3561805	commit-graph write: don't die if the existing graph is corrupt 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 <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	67a530fab3	commit-graph: don't pass filename to load_commit_graph_one_fd_st() 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 <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	61df89c8e5	commit-graph: don't early exit(1) on e.g. "git status" 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 <avarab@gmail.com> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	2ac138d568	commit-graph: fix segfault on e.g. "git status" When core.commitGraph=true is set, various common commands now consult the commit graph. Because the commit-graph code is very trusting of its input data, it's possibly to construct a graph that'll cause an immediate segfault on e.g. "status" (and e.g. "log", "blame", ...). In some other cases where git immediately exits with a cryptic error about the graph being broken. The root cause of this is that while the "commit-graph verify" sub-command exhaustively verifies the graph, other users of the graph simply trust the graph, and will e.g. deference data found at certain offsets as pointers, causing segfaults. This change does the bare minimum to ensure that we don't segfault in the common fill_commit_in_graph() codepath called by e.g. setup_revisions(), to do this instrument the "commit-graph verify" tests to always check if "status" would subsequently segfault. This fixes the following tests which would previously segfault: not ok 50 - detect low chunk count not ok 51 - detect missing OID fanout chunk not ok 52 - detect missing OID lookup chunk not ok 53 - detect missing commit data chunk Those happened because with the commit-graph enabled setup_revisions() would eventually call fill_commit_in_graph(), where e.g. g->chunk_commit_data is used early as an offset (and will be 0x0). With this change we get far enough to detect that the graph is broken, and show an error instead. E.g.: $ git status; echo $? error: commit-graph is missing the Commit Data chunk 1 That also sucks, we should warn and not hard-fail "status" just because the commit-graph is corrupt, but fixing is left to a follow-up change. A side-effect of changing the reporting from graph_report() to error() is that we now have an "error: " prefix for these even for "commit-graph verify". Pseudo-diff before/after: $ git commit-graph verify -commit-graph is missing the Commit Data chunk +error: commit-graph is missing the Commit Data chunk Changing that is OK. Various errors it emits now early on are prefixed with "error: ", moving these over and changing the output doesn't break anything. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	49bbc57a57	commit-graph write: emit a percentage for all progress Follow-up `01ca387774` ("commit-graph: split up close_reachable() progress output", 2018-11-19) by making the progress bars in close_reachable() report a completion percentage. This fixes the last occurrence where in the commit graph writing where we didn't report that. The change in `01ca387774` split up the 1x progress bar in close_reachable() into 3x, but left them as dumb counters without a percentage completion. Fixing that is easy, and the only reason it wasn't done already is because that commit was rushed in during the v2.20.0 RC period to fix the unrelated issue of over-reporting commit numbers. See [1] and follow-ups for ML activity at the time and [2] for an alternative approach where the progress bars weren't split up. Now for e.g. linux.git we'll emit: $ ~/g/git/git --exec-path=$HOME/g/git commit-graph write Finding commits for commit graph among packed objects: 100% (6529159/6529159), done. Expanding reachable commits in commit graph: 100% (815990/815980), done. Computing commit graph generation numbers: 100% (815983/815983), done. Writing out commit graph in 4 passes: 100% (3263932/3263932), done. 1. https://public-inbox.org/git/20181119202300.18670-1-avarab@gmail.com/ 2. https://public-inbox.org/git/20181122153922.16912-11-avarab@gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	890226ccb5	commit-graph write: add itermediate progress Add progress output to sections of code between "Annotating[...]" and "Computing[...]generation numbers". This can collectively take 5-10 seconds on a large enough repository. On a test repository with I have with ~7 million commits and ~50 million objects we'll now emit: $ ~/g/git/git --exec-path=$HOME/g/git commit-graph write Finding commits for commit graph among packed objects: 100% (124763727/124763727), done. Loading known commits in commit graph: 100% (18989461/18989461), done. Expanding reachable commits in commit graph: 100% (18989507/18989461), done. Clearing commit marks in commit graph: 100% (18989507/18989507), done. Counting distinct commits in commit graph: 100% (18989507/18989507), done. Finding extra edges in commit graph: 100% (18989507/18989507), done. Computing commit graph generation numbers: 100% (7250302/7250302), done. Writing out commit graph in 4 passes: 100% (29001208/29001208), done. Whereas on a medium-sized repository such as linux.git these new progress bars won't have time to kick in and as before and we'll still emit output like: $ ~/g/git/git --exec-path=$HOME/g/git commit-graph write Finding commits for commit graph among packed objects: 100% (6529159/6529159), done. Expanding reachable commits in commit graph: 815990, done. Computing commit graph generation numbers: 100% (815983/815983), done. Writing out commit graph in 4 passes: 100% (3263932/3263932), done. The "Counting distinct commits in commit graph" phase will spend most of its time paused at "0/*" as we QSORT(...) the list. That's not optimal, but at least we don't seem to be stalling anymore most of the time. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	e59c615e3c	commit-graph write: remove empty line for readability Remove the empty line between a QSORT(...) and the subsequent oideq() for-loop. This makes it clearer that the QSORT(...) is being done so that we can run the oideq() loop on adjacent OIDs. Amends code added in `08fd81c9b6` ("commit-graph: implement write_commit_graph()", 2018-04-02). Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	7c7b8a7fc7	commit-graph write: add more descriptive progress output Make the progress output shown when we're searching for commits to include in the graph more descriptive. This amends code I added in `7b0f229222` ("commit-graph write: add progress output", 2018-09-17). Now, on linux.git, we'll emit this sort of output in the various modes we support: $ git commit-graph write Finding commits for commit graph among packed objects: 100% (6529159/6529159), done. [...] # Actually we don't emit this since this takes almost no time at # all. But if we did (s/_delayed//) we'd show: $ git for-each-ref --format='%(objectname)' \| git commit-graph write --stdin-commits Finding commits for commit graph from 630 refs: 100% (630/630), done. [...] $ (cd .git/objects/pack/ && ls *idx) \| git commit-graph write --stdin-pack Finding commits for commit graph in 3 packs: 6529159, done. [...] The middle on of those is going to be the output users might see in practice, since it'll be emitted when they get the commit graph via gc.writeCommitGraph=true. But as noted above you need a really large number of refs for this message to show. It'll show up on a test repository I have with ~165k refs: Finding commits for commit graph from 165203 refs: 100% (165203/165203), done. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	d9b1b309cf	commit-graph write: show progress for object search Show the percentage progress for the "Finding commits for commit graph" phase for the common case where we're operating on all packs in the repository, as "commit-graph write" or "gc" will do. Before we'd emit on e.g. linux.git with "commit-graph write": Finding commits for commit graph: 6529159, done. [...] And now: Finding commits for commit graph: 100% (6529159/6529159), done. [...] Since the commit graph only includes those commits that are packed (via for_each_packed_object(...)) the approximate_object_count() returns the actual number of objects we're going to process. Still, it is possible due to a race with "gc" or another process maintaining packs that the number of objects we're going to process is lower than what approximate_object_count() reported. In that case we don't want to stop the progress bar short of 100%. So let's make sure it snaps to 100% at the end. The inverse case is also possible and more likely. I.e. that a new pack has been added between approximate_object_count() and for_each_packed_object(). In that case the percentage will go beyond 100%, and we'll do nothing to snap it back to 100% at the end. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	289447397c	commit-graph write: more descriptive "writing out" output Make the "Writing out" part of the progress output more descriptive. Depending on the shape of the graph we either make 3 or 4 passes over it. Let's present this information to the user in case they're wondering what this number, which is much larger than their number of commits, has to do with writing out the commit graph. Now e.g. on linux.git we emit: $ ~/g/git/git --exec-path=$HOME/g/git -C ~/g/linux commit-graph write Finding commits for commit graph: 6529159, done. Expanding reachable commits in commit graph: 815990, done. Computing commit graph generation numbers: 100% (815983/815983), done. Writing out commit graph in 4 passes: 100% (3263932/3263932), done. A note on i18n: Why are we using the Q_() function and passing a number & English text for a singular which'll never be used? Because the plural rules of translated languages may not match those of English, and to use the plural function we need to use this format. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	53035c4f0b	commit-graph write: add "Writing out" progress output Add progress output to be shown when we're writing out the commit-graph, this adds to the output already added in `7b0f229222` ("commit-graph write: add progress output", 2018-09-17). As noted in that commit most of the progress output isn't displayed on small repositories, but before this change we'd noticeably hang for 2-3 seconds at the end on medium sized repositories such as linux.git. Now we'll instead show output like this, and reduce the human-observable times at which we're not producing progress output: $ ~/g/git/git --exec-path=$HOME/g/git -C ~/g/2015-04-03-1M-git commit-graph write Finding commits for commit graph: 13064614, done. Expanding reachable commits in commit graph: 1000447, done. Computing commit graph generation numbers: 100% (1000447/1000447), done. Writing out commit graph: 100% (3001341/3001341), done. This "Writing out" number is 3x or 4x the number of commits, depending on the graph we're processing. A later change will make this explicit to the user. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
SZEDER Gábor	857ba928a4	commit-graph: don't call write_graph_chunk_extra_edges() unnecessarily The optional 'Extra Edge List' chunk of the commit graph file stores parent information for commits with more than two parents. Since the chunk is optional, write_commit_graph() looks through all commits to find those with more than two parents, and then writes the commit graph file header accordingly, i.e. if there are no such commits, then there won't be a 'Extra Edge List' chunk written, only the three mandatory chunks. However, when it later comes to writing actual chunk data, write_commit_graph() unconditionally invokes write_graph_chunk_extra_edges(), even when it was decided earlier that that chunk won't be written. Strictly speaking there is no bug here, because write_graph_chunk_extra_edges() won't write anything if it doesn't find any commits with more than two parents, but then it unnecessarily and in vain looks through all commits once again in search for such commits. Don't call write_graph_chunk_extra_edges() when that chunk won't be written to spare an unnecessary iteration over all commits. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
SZEDER Gábor	5af7417bd8	commit-graph: rename "large edges" to "extra edges" 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 <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	d7574c95bb	commit-graph write: use pack order when finding commits Slightly optimize the "commit-graph write" step by using FOR_EACH_OBJECT_PACK_ORDER with for_each_object_in_pack(). See commit [1] and [2] for the facility and a similar optimization for "cat-file". On Linux it is around 5% slower to run: echo 1 >/proc/sys/vm/drop_caches && cat .git/objects/pack/* >/dev/null && git cat-file --batch-all-objects --batch-check --unordered Than the same thing with the "cat" omitted. This is as expected, since we're iterating in pack order and the "cat" is extra work. Before this change the opposite was true of "commit-graph write". We were 6% faster if we first ran "cat" to efficiently populate the FS cache for our sole big pack on linux.git, than if we had populated it via for_each_object_in_pack(). Now we're 3% faster without the "cat" instead. My tests were done on an unloaded Linux 3.10 system with 10 runs for each. Derrick Stolee did his own tests on Windows[3] showing a 2% improvement with a high degree of accuracy. 1. `736eb88fdc` ("for_each_packed_object: support iterating in pack-order", 2018-08-10) 2. `0750bb5b51` ("cat-file: support "unordered" output for --batch-all-objects", 2018-08-10) 3. https://public-inbox.org/git/f71fa868-25e8-a9c9-46a6-611b987f1a8f@gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Josh Steadmon	d2b86fbaa1	commit-graph: fix buffer read-overflow fuzz-commit-graph identified a case where Git will read past the end of a buffer containing a commit graph if the graph's header has an incorrect chunk count. A simple bounds check in parse_commit_graph() prevents this. Signed-off-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Josh Steadmon	aa658574bf	commit-graph, fuzz: add fuzzer for commit-graph 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 <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Derrick Stolee	cce99cd8c6	commit-graph: writing missing parents is a BUG When writing a commit-graph, we write GRAPH_MISSING_PARENT if the parent's object id does not appear in the list of commits to be written into the commit-graph. This was done as the initial design allowed commits to have missing parents, but the final version requires the commit-graph to be closed under reachability. Thus, this GRAPH_MISSING_PARENT value should never be written. However, there are reasons why it could be written! These range from a bug in the reachable-closure code to a memory error causing the binary search into the list of object ids to fail. In either case, we should fail fast and avoid writing the commit-graph file with bad data. Remove the GRAPH_MISSING_PARENT constant in favor of the constant GRAPH_EDGE_LAST_MASK, which has the same value. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Stefan Beller	4f542b7a7f	commit-graph: convert remaining functions to handle any repo Convert all functions to handle arbitrary repositories in commit-graph.c that are used by functions taking a repository argument already. Notable exclusion is write_commit_graph and its local functions as that only works on the_repository. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Ævar Arnfjörð Bjarmason	01ca387774	commit-graph: split up close_reachable() progress output Amend the progress output added in `7b0f229222` ("commit-graph write: add progress output", 2018-09-17) so that the total numbers it reports aren't higher than the total number of commits anymore. See [1] for a bug report pointing that out. When I added this I wasn't intending to provide an accurate count, but just have some progress output to show the user the command wasn't hanging[2]. But since we are showing numbers, let's make them accurate. The progress descriptions were suggested by Derrick Stolee in [3]. As noted in [2] we are unlikely to show anything except the "Expanding reachable..." message even on fairly large repositories such as linux.git. On a test repository I have with north of 7 million commits all of these are displayed. Two of them don't show up for long, but as noted in [5] future-proofing this for if the loops become more expensive in the future makes sense. 1. https://public-inbox.org/git/20181010203738.GE23446@szeder.dev/ 2. https://public-inbox.org/git/87pnwhea8y.fsf@evledraar.gmail.com/ 3. https://public-inbox.org/git/f7a0cbee-863c-61d3-4959-5cec8b43c705@gmail.com/ 4. https://public-inbox.org/git/20181015160545.GG19800@szeder.dev/ 5. https://public-inbox.org/git/87murle8da.fsf@evledraar.gmail.com/ Reported-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Derrick Stolee <stolee@gmail.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
brian m. carlson	c166599862	commit-graph: convert to using the_hash_algo Instead of using hard-coded constants for object sizes, use the_hash_algo to look them up. In addition, use a function call to look up the object ID version and produce the correct value. For now, we use version 1, which means to use the default algorithm used in the rest of the repository. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Jeff King	f0eaf63819	sha1-file: use an object_directory for the main object dir Our handling of alternate object directories is needlessly different from the main object directory. As a result, many places in the code basically look like this: do_something(r->objects->objdir); for (odb = r->objects->alt_odb_list; odb; odb = odb->next) do_something(odb->path); That gets annoying when do_something() is non-trivial, and we've resorted to gross hacks like creating fake alternates (see find_short_object_filename()). Instead, let's give each raw_object_store a unified list of object_directory structs. The first will be the main store, and everything after is an alternate. Very few callers even care about the distinction, and can just loop over the whole list (and those who care can just treat the first element differently). A few observations: - we don't need r->objects->objectdir anymore, and can just mechanically convert that to r->objects->odb->path - object_directory's path field needs to become a real pointer rather than a FLEX_ARRAY, in order to fill it with expand_base_dir() - we'll call prepare_alt_odb() earlier in many functions (i.e., outside of the loop). This may result in us calling it even when our function would be satisfied looking only at the main odb. But this doesn't matter in practice. It's not a very expensive operation in the first place, and in the majority of cases it will be a noop. We call it already (and cache its results) in prepare_packed_git(), and we'll generally check packs before loose objects. So essentially every program is going to call it immediately once per program. Arguably we should just prepare_alt_odb() immediately upon setting up the repository's object directory, which would save us sprinkling calls throughout the code base (and forgetting to do so has been a source of subtle bugs in the past). But I've stopped short of that here, since there are already a lot of other moving parts in this patch. - Most call sites just get shorter. The check_and_freshen() functions are an exception, because they have entry points to handle local and nonlocal directories separately. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Jeff King	263db403fa	rename "alternate_object_database" to "object_directory" In preparation for unifying the handling of alt odb's and the normal repo object directory, let's use a more neutral name. This patch is purely mechanical, swapping the type name, and converting any variables named "alt" to "odb". There should be no functional change, but it will reduce the noise in subsequent diffs. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Derrick Stolee	53c36670e7	commit-graph: reduce initial oid allocation While writing a commit-graph file, we store the full list of commits in a flat list. We use this list for sorting and ensuring we are closed under reachability. The initial allocation assumed that (at most) one in four objects is a commit. This is a dramatic over-count for many repos, especially large ones. Since we grow the repo dynamically, reduce this count by a factor of eight. We still set it to a minimum of 1024 before allocating. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	f4dbdfc4d5	commit-graph: clean up leaked memory during write The write_commit_graph() method in commit-graph.c leaks some lits and strings during execution. In addition, a list of strings is leaked in write_commit_graph_reachable(). Clean these up so our memory checking is cleaner. Further, if we use a list of pack-files to find the commits, we can leak the packed_git structs after scanning them for commits. Running the following commands demonstrates the leak before and the fix after: * valgrind --leak-check=full ./git commit-graph write --reachable * valgrind --leak-check=full ./git commit-graph write --stdin-packs Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Ævar Arnfjörð Bjarmason	1f7f557fd3	commit-graph verify: add progress output For the reasons explained in the "commit-graph write: add progress output" commit leading up to this one, emit progress on "commit-graph verify". Since `e0fd51e1d7` ("fsck: verify commit-graph", 2018-06-27) "git fsck" has called this command if core.commitGraph=true, but there's been no progress output to indicate that anything was different. Now there is (on my tiny dotfiles.git repository): $ git -c core.commitGraph=true -C ~/ fsck Checking object directories: 100% (256/256), done. Checking objects: 100% (2821/2821), done. dangling blob 5b8bbdb9b788ed90459f505b0934619c17cc605b Verifying commits in commit graph: 100% (867/867), done. And on a larger repository, such as the 2015-04-03-1M-git.git test repository: $ time git -c core.commitGraph=true -C ~/g/2015-04-03-1M-git/ commit-graph verify Verifying commits in commit graph: 100% (1000447/1000447), done. real 0m7.813s [...] Since the "commit-graph verify" subcommand is never called from "git gc", we don't have to worry about passing some some "report_progress" progress variable around for this codepath. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Ævar Arnfjörð Bjarmason	7b0f229222	commit-graph write: add progress output Before this change the "commit-graph write" command didn't report any progress. On my machine this command takes more than 10 seconds to write the graph for linux.git, and around 1m30s on the 2015-04-03-1M-git.git[1] test repository (a test case for a large monorepository). Furthermore, since the gc.writeCommitGraph setting was added in `d5d5d7b641` ("gc: automatically write commit-graph files", 2018-06-27), there was no indication at all from a "git gc" run that anything was different. This why one of the progress bars being added here uses start_progress() instead of start_delayed_progress(), so that it's guaranteed to be seen. E.g. on my tiny 867 commit dotfiles.git repository: $ git -c gc.writeCommitGraph=true gc Enumerating objects: 2821, done. [...] Computing commit graph generation numbers: 100% (867/867), done. On larger repositories, such as linux.git the delayed progress bar(s) will kick in, and we'll show what's going on instead of, as was previously happening, printing nothing while we write the graph: $ git -c gc.writeCommitGraph=true gc [...] Annotating commits in commit graph: 1565573, done. Computing commit graph generation numbers: 100% (782484/782484), done. Note that here we don't show "Finding commits for commit graph", this is because under "git gc" we seed the search with the commit references in the repository, and that set is too small to show any progress, but would e.g. on a smaller repo such as git.git with --stdin-commits: $ git rev-list --all \| git -c gc.writeCommitGraph=true write --stdin-commits Finding commits for commit graph: 100% (162576/162576), done. Computing commit graph generation numbers: 100% (162576/162576), done. With --stdin-packs we don't show any estimation of how much is left to do. This is because we might be processing more than one pack. We could be less lazy here and show progress, either by detecting that we're only processing one pack, or by first looping over the packs to discover how many commits they have. I don't see the point in doing that work. So instead we get (on 2015-04-03-1M-git.git): $ echo pack-<HASH>.idx \| git -c gc.writeCommitGraph=true --exec-path=$PWD commit-graph write --stdin-packs Finding commits for commit graph: 13064614, done. Annotating commits in commit graph: 3001341, done. Computing commit graph generation numbers: 100% (1000447/1000447), done. No GC mode uses --stdin-packs. It's what they use at Microsoft to manually compute the generation numbers for their collection of large packs which are never coalesced. The reason we need a "report_progress" variable passed down from "git gc" is so that we don't report this output when we're running in the process "git gc --auto" detaches from the terminal. Since we write the commit graph from the "git gc" process itself (as opposed to what we do with say the "git repack" phase), we'd end up writing the output to .git/gc.log and reporting it to the user next time as part of the "The last gc run reported the following[...]" error, see `329e6e8794` ("gc: save log from daemonized gc --auto and print it next time", 2015-09-19). So we must keep track of whether or not we're running in that demonized mode, and if so print no progress. See [2] and subsequent replies for a discussion of an approach not taken in compute_generation_numbers(). I.e. we're saying "Computing commit graph generation numbers", even though on an established history we're mostly skipping over all the work we did in the past. This is similar to the white lie we tell in the "Writing objects" phase (not all are objects being written). Always showing progress is considered more important than accuracy. I.e. on a repository like 2015-04-03-1M-git.git we'd hang for 6 seconds with no output on the second "git gc" if no changes were made to any objects in the interim if we'd take the approach in [2]. 1. https://github.com/avar/2015-04-03-1M-git 2. <c6960252-c095-fb2b-e0bc-b1e6bb261614@gmail.com> (https://public-inbox.org/git/c6960252-c095-fb2b-e0bc-b1e6bb261614@gmail.com/) Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jeff King	67947c34ae	convert "hashcmp() != 0" to "!hasheq()" This rounds out the previous three patches, covering the inequality logic for the "hash" variant of the functions. As with the previous three, the accompanying code changes are the mechanical result of applying the coccinelle patch; see those patches for more discussion. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jeff King	9001dc2a74	convert "oidcmp() != 0" to "!oideq()" This is the flip side of the previous two patches: checking for a non-zero oidcmp() can be more strictly expressed as inequality. Like those patches, we write "!= 0" in the coccinelle transformation, which covers by isomorphism the more common: if (oidcmp(E1, E2)) As with the previous two patches, this patch can be achieved almost entirely by running "make coccicheck"; the only differences are manual line-wrap fixes to match the original code. There is one thing to note for anybody replicating this, though: coccinelle 1.0.4 seems to miss the case in builtin/tag.c, even though it's basically the same as all the others. Running with 1.0.7 does catch this, so presumably it's just a coccinelle bug that was fixed in the interim. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jeff King	4a7e27e957	convert "oidcmp() == 0" to oideq() Using the more restrictive oideq() should, in the long run, give the compiler more opportunities to optimize these callsites. For now, this conversion should be a complete noop with respect to the generated code. The result is also perhaps a little more readable, as it avoids the "zero is equal" idiom. Since it's so prevalent in C, I think seasoned programmers tend not to even notice it anymore, but it can sometimes make for awkward double negations (e.g., we can drop a few !!oidcmp() instances here). This patch was generated almost entirely by the included coccinelle patch. This mechanical conversion should be completely safe, because we check explicitly for cases where oidcmp() is compared to 0, which is what oideq() is doing under the hood. Note that we don't have to catch "!oidcmp()" separately; coccinelle's standard isomorphisms make sure the two are treated equivalently. I say "almost" because I did hand-edit the coccinelle output to fix up a few style violations (it mostly keeps the original formatting, but sometimes unwraps long lines). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	859fdc0c3c	commit-graph: define GIT_TEST_COMMIT_GRAPH The commit-graph feature is tested in isolation by t5318-commit-graph.sh and t6600-test-reach.sh, but there are many more interesting scenarios involving commit walks. Many of these scenarios are covered by the existing test suite, but we need to maintain coverage when the optional commit-graph structure is not present. To allow running the full test suite with the commit-graph present, add a new test environment variable, GIT_TEST_COMMIT_GRAPH. Similar to GIT_TEST_SPLIT_INDEX, this variable makes every Git command try to load the commit-graph when parsing commits, and writes the commit-graph file after every 'git commit' command. There are a few tests that rely on commits not existing in pack-files to trigger important events, so manually set GIT_TEST_COMMIT_GRAPH to false for the necessary commands. There is one test in t6024-recursive-merge.sh that relies on the merge-base algorithm picking one of two ambiguous merge-bases, and the commit-graph feature changes which merge-base is picked. Helped-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	829a321569	commit-graph: close_commit_graph before shallow walk Call close_commit_graph() when about to start a rev-list walk that includes shallow commits. This is necessary in code paths that "fake" shallow commits for the sake of fetch. Specifically, test 351 in t5500-fetch-pack.sh runs git fetch --shallow-exclude one origin with a file-based transfer. When the "remote" has a commit-graph, we do not prevent the commit-graph from being loaded, but then the commits are intended to be dynamically transferred into shallow commits during get_shallow_commits_by_rev_list(). By closing the commit-graph before this call, we prevent this interaction. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	5cef295f28	commit-graph: not compatible with uninitialized repo Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	20fd6d5799	commit-graph: not compatible with grafts Augment commit_graph_compatible(r) to return false when the given repository r has commit grafts or is a shallow clone. Test that in these situations we ignore existing commit-graph files and we do not write new commit-graph files. Helped-by: Jakub Narebski <jnareb@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	d6538246d3	commit-graph: not compatible with replace objects Create new method commit_graph_compatible(r) to check if a given repository r is compatible with the commit-graph feature. Fill the method with a check to see if replace-objects exist. Test this interaction succeeds, including ignoring an existing commit-graph and failing to write a new commit-graph. However, we do ensure that we write a new commit-graph by setting read_replace_refs to 0, thereby ignoring the replace refs. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jeff King	736eb88fdc	for_each_packed_object: support iterating in pack-order 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 <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Nguyễn Thái Ngọc Duy	4f5b532d18	commit-graph.c: mark more strings for translation Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	6cc017431c	commit-reach: use can_all_from_reach The is_descendant_of method previously used in_merge_bases() to check if the commit can reach any of the commits in the provided list. This had two performance problems: 1. The performance is quadratic in worst-case. 2. A single in_merge_bases() call requires walking beyond the target commit in order to find the full set of boundary commits that may be merge-bases. The can_all_from_reach method avoids this quadratic behavior and can limit the search beyond the target commits using generation numbers. It requires a small prototype adjustment to stop using commit-date as a cutoff, as that optimization is no longer appropriate here. Since in_merge_bases() uses paint_down_to_common(), is_descendant_of() naturally found cutoffs to avoid walking the entire commit graph. Since we want to always return the correct result, we cannot use the min_commit_date cutoff in can_all_from_reach. We then rely on generation numbers to provide the cutoff. Since not all repos will have a commit-graph file, nor will we always have generation numbers computed for a commit-graph file, create a new method, generation_numbers_enabled(), that checks for a commit-graph file and sees if the first commit in the file has a non-zero generation number. In the case that we do not have generation numbers, use the old logic for is_descendant_of(). Performance was meausured on a copy of the Linux repository using the 'test-tool reach is_descendant_of' command using this input: A:v4.9 X:v4.10 X:v4.11 X:v4.12 X:v4.13 X:v4.14 X:v4.15 X:v4.16 X:v4.17 X.v3.0 Note that this input is tailored to demonstrate the quadratic nature of the previous method, as it will compute merge-bases for v4.9 versus all of the later versions before checking against v4.1. Before: 0.26 s After: 0.21 s Since we previously used the is_descendant_of method in the ref_newer method, we also measured performance there using 'test-tool reach ref_newer' with this input: A:v4.9 B:v3.19 Before: 0.10 s After: 0.08 s By adding a new commit with parent v3.19, we test the non-reachable case of ref_newer: Before: 0.09 s After: 0.08 s Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jonathan Tan	dade47c06c	commit-graph: add repo arg to graph readers Add a struct repository argument to the functions in commit-graph.h that read the commit graph. (This commit does not affect functions that write commit graphs.) Because the commit graph functions can now read the commit graph of any repository, the global variable core_commit_graph has been removed. Instead, the config option core.commitGraph is now read on the first time in a repository that a commit is attempted to be parsed using its commit graph. This commit includes a test that exercises the functionality on an arbitrary repository that is not the_repository. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jonathan Tan	8527750626	commit-graph: store graph in struct object_store Instead of storing commit graphs in static variables, store them in struct object_store. There are no changes to the signatures of existing functions - they all still only support the_repository, and support for other instances of struct repository will be added in a subsequent commit. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jonathan Tan	c3756d5b7f	commit-graph: add free_commit_graph Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jonathan Tan	5faf357b43	commit-graph: refactor preparing commit graph Two functions in the code (1) check if the repository is configured for commit graphs, (2) call prepare_commit_graph(), and (3) check if the graph exists. Move (1) and (3) into prepare_commit_graph(), reducing duplication of code. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	c1f5eb4962	commit: add repository argument to lookup_commit Add a repository argument to allow callers of lookup_commit to be more specific about which repository to handle. 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: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	21e1ee8f4f	commit: add repository argument to lookup_commit_reference_gently Add a repository argument to allow callers of lookup_commit_reference_gently to be more specific about which repository to handle. 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: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	f86bcc7b2c	tree: add repository argument to lookup_tree Add a repository argument to allow the callers of lookup_tree 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 <jrnieder@gmail.com> Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	59fb87701f	commit-graph: add '--reachable' option When writing commit-graph files, it can be convenient to ask for all reachable commits (starting at the ref set) in the resulting file. This is particularly helpful when writing to stdin is complicated, such as a future integration with 'git gc'. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	d88b14b3fd	commit-graph: use string-list API for input Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	41df0e307f	commit-graph: verify contents match checksum The commit-graph file ends with a SHA1 hash of the previous contents. If a commit-graph file has errors but the checksum hash is correct, then we know that the problem is a bug in Git and not simply file corruption after-the-fact. Compute the checksum right away so it is the first error that appears, and make the message translatable since this error can be "corrected" by a user by simply deleting the file and recomputing. The rest of the errors are useful only to developers. Be sure to continue checking the rest of the file data if the checksum is wrong. This is important for our tests, as we break the checksum as we modify bytes of the commit-graph file. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	88968ebf86	commit-graph: verify commit date Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	1373e547f7	commit-graph: verify generation number While iterating through the commit parents, perform the generation number calculation and compare against the value stored in the commit-graph. The tests demonstrate that having a different set of parents affects the generation number calculation, and this value propagates to descendants. Hence, we drop the single-line condition on the output. Since Git will ship with the commit-graph feature without generation numbers, we need to accept commit-graphs with all generation numbers equal to zero. In this case, ignore the generation number calculation. However, verify that we should never have a mix of zero and non-zero generation numbers. Create a test that sets one commit to generation zero and all following commits report a failure as they have non-zero generation in a file that contains generation number zero. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	53614b1351	commit-graph: verify parent list The commit-graph file stores parents in a two-column portion of the commit data chunk. If there is only one parent, then the second column stores 0xFFFFFFFF to indicate no second parent. The 'verify' subcommand checks the parent list for the commit loaded from the commit-graph and the one parsed from the object database. Test these checks for corrupt parents, too many parents, and wrong parents. Add a boundary check to insert_parent_or_die() for when the parent position value is out of range. The octopus merge will be tested in a later commit. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago

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