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2019-10-09Merge branch 'ah/cleanups'Junio C Hamano
Miscellaneous code clean-ups. * ah/cleanups: git_mkstemps_mode(): replace magic numbers with computed value wrapper: use a loop instead of repetitive statements diffcore-break: use a goto instead of a redundant if statement commit-graph: remove a duplicate assignment
2019-10-07Merge branch 'tb/commit-graph-harden'Junio C Hamano
The code to parse and use the commit-graph file has been made more robust against corrupted input. * tb/commit-graph-harden: commit-graph.c: handle corrupt/missing trees commit-graph.c: handle commit parsing errors t/t5318: introduce failing 'git commit-graph write' tests
2019-10-07Merge branch 'gs/commit-graph-progress'Junio C Hamano
* gs/commit-graph-progress: commit-graph: add --[no-]progress to write and verify
2019-10-07Merge branch 'rs/commit-graph-use-list-count'Junio C Hamano
Code cleanup. * rs/commit-graph-use-list-count: commit-graph: use commit_list_count()
2019-10-07Merge branch 'jk/disable-commit-graph-during-upload-pack'Junio C Hamano
The "upload-pack" (the counterpart of "git fetch") needs to disable commit-graph when responding to a shallow clone/fetch request, but the way this was done made Git panic, which has been corrected. * jk/disable-commit-graph-during-upload-pack: upload-pack: disable commit graph more gently for shallow traversal commit-graph: bump DIE_ON_LOAD check to actual load-time
2019-10-07Merge branch 'jk/commit-graph-cleanup'Junio C Hamano
A pair of small fixups to "git commit-graph" have been applied. * jk/commit-graph-cleanup: commit-graph: turn off save_commit_buffer commit-graph: don't show progress percentages while expanding reachable commits
2019-10-02commit-graph: remove a duplicate assignmentAlex Henrie
Leave the variable 'g' uninitialized before it is set just before its first use in front of a loop, which is a much more appropriate place to indicate what it is used for. Also initialize the variable 'num_commits' just before the loop instead of at the beginning of the function for the same reason. Reviewed-by: Derrick Stolee <stolee@gmail.com> Signed-off-by: Alex Henrie <alexhenrie24@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-18commit-graph: add --[no-]progress to write and verifyGarima Singh
Add --[no-]progress to git commit-graph write and verify. The progress feature was introduced in 7b0f229 ("commit-graph write: add progress output", 2018-09-17) but the ability to opt-out was overlooked. Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-16commit-graph: use commit_list_count()René Scharfe
Let commit_list_count() count the number of parents instead of duplicating it. Also store the result in an unsigned int, as that's what the function returns, and the count is never negative. Signed-off-by: René Scharfe <l.s.r@web.de> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-12upload-pack: disable commit graph more gently for shallow traversalJeff King
When the client has asked for certain shallow options like "deepen-since", we do a custom rev-list walk that pretends to be shallow. Before doing so, we have to disable the commit-graph, since it is not compatible with the shallow view of the repository. That's handled by 829a321569 (commit-graph: close_commit_graph before shallow walk, 2018-08-20). That commit literally closes and frees our repo->objects->commit_graph struct. That creates an interesting problem for commits that have _already_ been parsed using the commit graph. Their commit->object.parsed flag is set, their commit->graph_pos is set, but their commit->maybe_tree may still be NULL. When somebody later calls repo_get_commit_tree(), we see that we haven't loaded the tree oid yet and try to get it from the commit graph. But since it has been freed, we segfault! So the root of the issue is a data dependency between the commit's lazy-load of the tree oid and the fact that the commit graph can go away mid-process. How can we resolve it? There are a couple of general approaches: 1. The obvious answer is to avoid loading the tree from the graph when we see that it's NULL. But then what do we return for the tree oid? If we return NULL, our caller in do_traverse() will rightly complain that we have no tree. We'd have to fallback to loading the actual commit object and re-parsing it. That requires teaching parse_commit_buffer() to understand re-parsing (i.e., not starting from a clean slate and not leaking any allocated bits like parent list pointers). 2. When we close the commit graph, walk through the set of in-memory objects and clear any graph_pos pointers. But this means we also have to "unparse" any such commits so that we know they still need to open the commit object to fill in their trees. So it's no less complicated than (1), and is more expensive (since we clear objects we might not later need). 3. Stop freeing the commit-graph struct. Continue to let it be used for lazy-loads of tree oids, but let upload-pack specify that it shouldn't be used for further commit parsing. 4. Push the whole shallow rev-list out to its own sub-process, with the commit-graph disabled from the start, giving it a clean memory space to work from. I've chosen (3) here. Options (1) and (2) would work, but are non-trivial to implement. Option (4) is more expensive, and I'm not sure how complicated it is (shelling out for the actual rev-list part is easy, but we do then parse the resulting commits internally, and I'm not clear which parts need to be handling shallow-ness). The new test in t5500 triggers this segfault, but see the comments there for how horribly intimate it has to be with how both upload-pack and commit graphs work. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-12commit-graph: bump DIE_ON_LOAD check to actual load-timeJeff King
Commit 43d3561805 (commit-graph write: don't die if the existing graph is corrupt, 2019-03-25) added an environment variable we use only in the test suite, $GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD. But it put the check for this variable at the very top of prepare_commit_graph(), which is called every time we want to use the commit graph. Most importantly, it comes _before_ we check the fast-path "did we already try to load?", meaning we end up calling getenv() for every single use of the commit graph, rather than just when we load. getenv() is allowed to have unexpected side effects, but that shouldn't be a problem here; we're lazy-loading the graph so it's clear that at least _one_ invocation of this function is going to call it. But it is inefficient. getenv() typically has to do a linear search through the environment space. We could memoize the call, but it's simpler still to just bump the check down to the actual loading step. That's fine for our sole user in t5318, and produces this minor real-world speedup: [before] Benchmark #1: git -C linux rev-list HEAD >/dev/null Time (mean ± σ): 1.460 s ± 0.017 s [User: 1.174 s, System: 0.285 s] Range (min … max): 1.440 s … 1.491 s 10 runs [after] Benchmark #1: git -C linux rev-list HEAD >/dev/null Time (mean ± σ): 1.391 s ± 0.005 s [User: 1.118 s, System: 0.273 s] Range (min … max): 1.385 s … 1.399 s 10 runs Of course that actual speedup depends on how big your environment is. We can game it like this: for i in $(seq 10000); do export dummy$i=$i done in which case I get: [before] Benchmark #1: git -C linux rev-list HEAD >/dev/null Time (mean ± σ): 6.257 s ± 0.061 s [User: 6.005 s, System: 0.250 s] Range (min … max): 6.174 s … 6.337 s 10 runs [after] Benchmark #1: git -C linux rev-list HEAD >/dev/null Time (mean ± σ): 1.403 s ± 0.005 s [User: 1.146 s, System: 0.256 s] Range (min … max): 1.396 s … 1.412 s 10 runs So this is really more about avoiding the pathological case than providing a big real-world speedup. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-09Merge branch 'ds/feature-macros'Junio C Hamano
A mechanism to affect the default setting for a (related) group of configuration variables is introduced. * ds/feature-macros: repo-settings: create feature.experimental setting repo-settings: create feature.manyFiles setting repo-settings: parse core.untrackedCache commit-graph: turn on commit-graph by default t6501: use 'git gc' in quiet mode repo-settings: consolidate some config settings
2019-09-09commit-graph: don't show progress percentages while expanding reachable commitsSZEDER Gábor
Commit 49bbc57a57 (commit-graph write: emit a percentage for all progress, 2019-01-19) was a bit overeager when it added progress percentages to the "Expanding reachable commits in commit graph" phase as well, because most of the time the number of commits that phase has to iterate over is not known in advance and grows significantly, and, consequently, we end up with nonsensical numbers: $ git commit-graph write --reachable Expanding reachable commits in commit graph: 138606% (824706/595), done. [...] $ git rev-parse v5.0 | git commit-graph write --stdin-commits Expanding reachable commits in commit graph: 81264400% (812644/1), done. [...] Even worse, because the percentage grows so quickly, the progress code outputs much more often than it should (because it ticks every second, or every 1%), slowing the whole process down. My time for "git commit-graph write --reachable" on linux.git went from 13.463s to 12.521s with this patch, ~7% savings. Therefore, don't show progress percentages in the "Expanding reachable commits in commit graph" phase. Note that the current code does sometimes do the right thing, if we picked up all commits initially (e.g., omitting "--reachable" in a fully-packed repository would get the correct count without any parent traversal). So it may be possible to come up with a way to tell when we could use a percentage here. But in the meantime, let's make sure we robustly avoid printing nonsense. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-09commit-graph.c: handle corrupt/missing treesTaylor Blau
Apply similar treatment as in the previous commit to handle an unchecked call to 'get_commit_tree_oid()'. Previously, a NULL return value from this function would be immediately dereferenced with '->hash', and then cause a segfault. Before dereferencing to access the 'hash' member, check the return value of 'get_commit_tree_oid()' to make sure that it is not NULL. To make this check correct, a related change is also needed in 'commit.c', which is to check the return value of 'get_commit_tree' before taking its address. If 'get_commit_tree' returns NULL, we encounter an undefined behavior when taking the address of the return value of 'get_commit_tree' and then taking '->object.oid'. (On my system, this is memory address 0x8, which is obviously wrong). Fix this by making sure that 'get_commit_tree' returns something non-NULL before digging through a structure that is not there, thus preventing a segfault down the line in the commit graph code. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-09commit-graph.c: handle commit parsing errorsTaylor Blau
To write a commit graph chunk, 'write_graph_chunk_data()' takes a list of commits to write and parses each one before writing the necessary data, and continuing on to the next commit in the list. Since the majority of these commits are not parsed ahead of time (an exception is made for the *last* commit in the list, which is parsed early within 'copy_oids_to_commits'), it is possible that calling 'parse_commit_no_graph()' on them may return an error. Failing to catch these errors before de-referencing later calls can result in a undefined memory access and a SIGSEGV. One such example of this is 'get_commit_tree_oid()', which expects a parsed object as its input (in this case, the commit-graph code passes '*list'). If '*list' causes a parse error, the subsequent call will fail. Prevent such an issue by checking the return value of 'parse_commit_no_graph()' to avoid passing an unparsed object to a function which expects a parsed object, thus preventing a segfault. It is worth noting that this fix is really skirting around the issue in object.c's 'parse_object()', which makes it difficult to tell how corrupt an object is without digging into it. Presumably one could change the meaning of 'parse_object' returns, but this would require adjusting each callsite accordingly. Instead of that, add an additional check to the object parsed. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-22Merge branch 'sg/commit-graph-validate'Junio C Hamano
The code to write commit-graph over given commit object names has been made a bit more robust. * sg/commit-graph-validate: commit-graph: error out on invalid commit oids in 'write --stdin-commits' commit-graph: turn a group of write-related macro flags into an enum t5318-commit-graph: use 'test_expect_code'
2019-08-13repo-settings: consolidate some config settingsDerrick Stolee
There are a few important config settings that are not loaded during git_default_config. These are instead loaded on-demand. Centralize these config options to a single scan, and store all of the values in a repo_settings struct. The values for each setting are initialized as negative to indicate "unset". This centralization will be particularly important in a later change to introduce "meta" config settings that change the defaults for these config settings. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-09Merge branch 'ds/commit-graph-incremental'Junio C Hamano
Leakfix. * ds/commit-graph-incremental: commit-graph: release strbufs after use
2019-08-07commit-graph: release strbufs after useRené Scharfe
Signed-off-by: René Scharfe <l.s.r@web.de> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-05commit-graph: fix bug around octopus mergesDerrick Stolee
In 1771be90 "commit-graph: merge commit-graph chains" (2019-06-18), the method sort_and_scan_merged_commits() was added to merge the commit lists of two commit-graph files in the incremental format. Unfortunately, there was an off-by-one error in that method around incrementing num_extra_edges, which leads to an incorrect offset for the base graph chunk. When we store an octopus merge in the commit-graph file, we store the first parent in the normal place, but use the second parent position to point into the "extra edges" chunk where the remaining parents exist. This means we should be adding "num_parents - 1" edges to this list, not "num_parents - 2". That is the basic error. The reason this was not caught in the test suite is more subtle. In 5324-split-commit-graph.sh, we test creating an octopus merge and adding it to the tip of a commit-graph chain, then verify the result. This _should_ have caught the problem, except that when we load the commit-graph files we were overly careful to not fail when the commit-graph chain does not match. This care was on purpose to avoid race conditions as one process reads the chain and another process modifies it. In such a case, the reading process outputs the following message to stderr: warning: commit-graph chain does not match These warnings are output in the test suite, but ignored. By checking the stderr of `git commit-graph verify` to include the expected progress output, it will now catch this error. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-05commit-graph: error out on invalid commit oids in 'write --stdin-commits'SZEDER Gábor
While 'git commit-graph write --stdin-commits' expects commit object ids as input, it accepts and silently skips over any invalid commit object ids, and still exits with success: # nonsense $ echo not-a-commit-oid | git commit-graph write --stdin-commits $ echo $? 0 # sometimes I forgot that refs are not good... $ echo HEAD | git commit-graph write --stdin-commits $ echo $? 0 # valid tree OID, but not a commit OID $ git rev-parse HEAD^{tree} | git commit-graph write --stdin-commits $ echo $? 0 $ ls -l .git/objects/info/commit-graph ls: cannot access '.git/objects/info/commit-graph': No such file or directory Check that all input records are indeed valid commit object ids and return with error otherwise, the same way '--stdin-packs' handles invalid input; see e103f7276f (commit-graph: return with errors during write, 2019-06-12). Note that it should only return with error when encountering an invalid commit object id coming from standard input. However, '--reachable' uses the same code path to process object ids pointed to by all refs, and that includes tag object ids as well, which should still be skipped over. Therefore add a new flag to 'enum commit_graph_write_flags' and a corresponding field to 'struct write_commit_graph_context', so we can differentiate between those two cases. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-05commit-graph: turn a group of write-related macro flags into an enumSZEDER Gábor
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-07-19Merge branch 'ds/commit-graph-incremental'Junio C Hamano
The commits in a repository can be described by multiple commit-graph files now, which allows the commit-graph files to be updated incrementally. * ds/commit-graph-incremental: commit-graph: test verify across alternates commit-graph: normalize commit-graph filenames commit-graph: test --split across alternate without --split commit-graph: test octopus merges with --split commit-graph: clean up chains after flattened write commit-graph: verify chains with --shallow mode commit-graph: create options for split files commit-graph: expire commit-graph files commit-graph: allow cross-alternate chains commit-graph: merge commit-graph chains commit-graph: add --split option to builtin commit-graph: write commit-graph chains commit-graph: rearrange chunk count logic commit-graph: add base graphs chunk commit-graph: load commit-graph chains commit-graph: rename commit_compare to oid_compare commit-graph: prepare for commit-graph chains commit-graph: document commit-graph chains
2019-07-09Merge branch 'jk/oidhash'Junio C Hamano
Code clean-up to remove hardcoded SHA-1 hash from many places. * jk/oidhash: hashmap: convert sha1hash() to oidhash() hash.h: move object_id definition from cache.h khash: rename oid helper functions khash: drop sha1-specific map types pack-bitmap: convert khash_sha1 maps into kh_oid_map delta-islands: convert island_marks khash to use oids khash: rename kh_oid_t to kh_oid_set khash: drop broken oid_map typedef object: convert create_object() to use object_id object: convert internal hash_obj() to object_id object: convert lookup_object() to use object_id object: convert lookup_unknown_object() to use object_id pack-objects: convert locate_object_entry_hash() to object_id pack-objects: convert packlist_find() to use object_id pack-bitmap-write: convert some helpers to use object_id upload-pack: rename a "sha1" variable to "oid" describe: fix accidental oid/hash type-punning
2019-07-09Merge branch 'ds/close-object-store'Junio C Hamano
The commit-graph file is now part of the "files that the runtime may keep open file descriptors on, all of which would need to be closed when done with the object store", and the file descriptor to an existing commit-graph file now is closed before "gc" finalizes a new instance to replace it. * ds/close-object-store: packfile: rename close_all_packs to close_object_store packfile: close commit-graph in close_all_packs commit-graph: use raw_object_store when closing
2019-07-09Merge branch 'ds/commit-graph-write-refactor'Junio C Hamano
Renamed from commit-graph-format-v2 and changed scope. * ds/commit-graph-write-refactor: commit-graph: extract write_commit_graph_file() commit-graph: extract copy_oids_to_commits() commit-graph: extract count_distinct_commits() commit-graph: extract fill_oids_from_all_packs() commit-graph: extract fill_oids_from_commit_hex() commit-graph: extract fill_oids_from_packs() commit-graph: create write_commit_graph_context commit-graph: remove Future Work section commit-graph: collapse parameters into flags commit-graph: return with errors during write commit-graph: fix the_repository reference
2019-06-20object: convert create_object() to use object_idJeff King
There are no callers left of create_object() that aren't just passing us the "hash" member of a "struct object_id". Let's take the whole struct, which gets us closer to removing all raw sha1 variables. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: normalize commit-graph filenamesDerrick Stolee
When writing commit-graph files, we append path data to an object directory, which may be specified by the user via the '--object-dir' option. If the user supplies a trailing slash, or some other alternative path format, the resulting path may be usable for writing to the correct location. However, when expiring graph files from the <obj-dir>/info/commit-graphs directory during a write, we need to compare paths with exact string matches. Normalize the commit-graph filenames to avoid ambiguity. This creates extra allocations, but this is a constant multiple of the number of commit-graph files, which should be a number in the single digits. Further normalize the object directory in the context. Due to a comparison between g->obj_dir and ctx->obj_dir in split_graph_merge_strategy(), a trailing slash would prevent any merging of layers within the same object directory. The check is there to ensure we do not merge across alternates. Update the tests to include a case with this trailing slash problem. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: clean up chains after flattened writeDerrick Stolee
If we write a commit-graph file without the split option, then we write to $OBJDIR/info/commit-graph and start to ignore the chains in $OBJDIR/info/commit-graphs/. Unlink the commit-graph-chain file and expire the graph-{hash}.graph files in $OBJDIR/info/commit-graphs/ during every write. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: verify chains with --shallow modeDerrick Stolee
If we wrote a commit-graph chain, we only modified the tip file in the chain. It is valuable to verify what we wrote, but not waste time checking files we did not write. Add a '--shallow' option to the 'git commit-graph verify' subcommand and check that it does not read the base graph in a two-file chain. Making the verify subcommand read from a chain of commit-graphs takes some rearranging of the builtin code. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: create options for split filesDerrick Stolee
The split commit-graph feature is now fully implemented, but needs some more run-time configurability. Allow direct callers to 'git commit-graph write --split' to specify the values used in the merge strategy and the expire time. Update the documentation to specify these values. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: expire commit-graph filesDerrick Stolee
As we merge commit-graph files in a commit-graph chain, we should clean up the files that are no longer used. This change introduces an 'expiry_window' value to the context, which is always zero (for now). We then check the modified time of each graph-{hash}.graph file in the $OBJDIR/info/commit-graphs folder and unlink the files that are older than the expiry_window. Since this is always zero, this immediately clears all unused graph files. We will update the value to match a config setting in a future change. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: allow cross-alternate chainsDerrick Stolee
In an environment like a fork network, it is helpful to have a commit-graph chain that spans both the base repo and the fork repo. The fork is usually a small set of data on top of the large repo, but sometimes the fork is much larger. For example, git-for-windows/git has almost double the number of commits as git/git because it rebases its commits on every major version update. To allow cross-alternate commit-graph chains, we need a few pieces: 1. When looking for a graph-{hash}.graph file, check all alternates. 2. When merging commit-graph chains, do not merge across alternates. 3. When writing a new commit-graph chain based on a commit-graph file in another object directory, do not allow success if the base file has of the name "commit-graph" instead of "commit-graphs/graph-{hash}.graph". Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: merge commit-graph chainsDerrick Stolee
When searching for a commit in a commit-graph chain of G graphs with N commits, the search takes O(G log N) time. If we always add a new tip graph with every write, the linear G term will start to dominate and slow the lookup process. To keep lookups fast, but also keep most incremental writes fast, create a strategy for merging levels of the commit-graph chain. The strategy is detailed in the commit-graph design document, but is summarized by these two conditions: 1. If the number of commits we are adding is more than half the number of commits in the graph below, then merge with that graph. 2. If we are writing more than 64,000 commits into a single graph, then merge with all lower graphs. The numeric values in the conditions above are currently constant, but can become config options in a future update. As we merge levels of the commit-graph chain, check that the commits still exist in the repository. A garbage-collection operation may have removed those commits from the object store and we do not want to persist them in the commit-graph chain. This is a non-issue if the 'git gc' process wrote a new, single-level commit-graph file. After we merge levels, the old graph-{hash}.graph files are no longer referenced by the commit-graph-chain file. We will expire these files in a future change. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: add --split option to builtinDerrick Stolee
Add a new "--split" option to the 'git commit-graph write' subcommand. This option allows the optional behavior of writing a commit-graph chain. The current behavior will add a tip commit-graph containing any commits that are not in the existing commit-graph or commit-graph chain. Later changes will allow merging the chain and expiring out-dated files. Add a new test script (t5324-split-commit-graph.sh) that demonstrates this behavior. Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: write commit-graph chainsDerrick Stolee
Extend write_commit_graph() to write a commit-graph chain when given the COMMIT_GRAPH_SPLIT flag. This implementation is purposefully simplistic in how it creates a new chain. The commits not already in the chain are added to a new tip commit-graph file. Much of the logic around writing a graph-{hash}.graph file and updating the commit-graph-chain file is the same as the commit-graph file case. However, there are several places where we need to do some extra logic in the split case. Track the list of graph filenames before and after the planned write. This will be more important when we start merging graph files, but it also allows us to upgrade our commit-graph file to the appropriate graph-{hash}.graph file when we upgrade to a chain of commit-graphs. Note that we use the eighth byte of the commit-graph header to store the number of base graph files. This determines the length of the base graphs chunk. A subtle change of behavior with the new logic is that we do not write a commit-graph if we our commit list is empty. This extends to the typical case, which is reflected in t5318-commit-graph.sh. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: rearrange chunk count logicDerrick Stolee
The number of chunks in a commit-graph file can change depending on whether we need the Extra Edges Chunk. We are going to add more optional chunks, and it will be helpful to rearrange this logic around the chunk count before doing so. Specifically, we need to finalize the number of chunks before writing the commit-graph header. Further, we also need to fill out the chunk lookup table dynamically and using "num_chunks" as we add optional chunks is useful for adding optional chunks in the future. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: add base graphs chunkDerrick Stolee
To quickly verify a commit-graph chain is valid on load, we will read from the new "Base Graphs Chunk" of each file in the chain. This will prevent accidentally loading incorrect data from manually editing the commit-graph-chain file or renaming graph-{hash}.graph files. The commit_graph struct already had an object_id struct "oid", but it was never initialized or used. Add a line to read the hash from the end of the commit-graph file and into the oid member. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: load commit-graph chainsDerrick Stolee
Prepare the logic for reading a chain of commit-graphs. First, look for a file at $OBJDIR/info/commit-graph. If it exists, then use that file and stop. Next, look for the chain file at $OBJDIR/info/commit-graphs/commit-graph-chain. If this file exists, then load the hash values as line-separated values in that file and load $OBJDIR/info/commit-graphs/graph-{hash[i]}.graph for each hash[i] in that file. The file is given in order, so the first hash corresponds to the "base" file and the final hash corresponds to the "tip" file. This implementation assumes that all of the graph-{hash}.graph files are in the same object directory as the commit-graph-chain file. This will be updated in a future change. This change is purposefully simple so we can isolate the different concerns. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: rename commit_compare to oid_compareDerrick Stolee
The helper function commit_compare() actually compares object_id structs, not commits. A future change to commit-graph.c will need to sort commit structs, so rename this function in advance. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-20commit-graph: prepare for commit-graph chainsDerrick Stolee
To prepare for a chain of commit-graph files, augment the commit_graph struct to point to a base commit_graph. As we load commits from the graph, we may actually want to read from a base file according to the graph position. The "graph position" of a commit is given by concatenating the lexicographic commit orders from each of the commit-graph files in the chain. This means that we must distinguish two values: * lexicographic index : the position within the lexicographic order in a single commit-graph file. * graph position: the position within the concatenated order of multiple commit-graph files Given the lexicographic index of a commit in a graph, we can compute the graph position by adding the number of commits in the lower-level graphs. To find the lexicographic index of a commit, we subtract the number of commits in lower-level graphs. While here, change insert_parent_or_die() to take a uint32_t position, as that is the type used by its only caller and that makes more sense with the limits in the commit-graph format. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: use raw_object_store when closingDerrick Stolee
The close_commit_graph() method took a repository struct, but then only uses the raw_object_store within. Change the function prototype to make the method more flexible. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract write_commit_graph_file()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. Extract write_commit_graph_file() that takes all of the information in the context struct and writes the data to a commit-graph file. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract copy_oids_to_commits()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. Extract copy_oids_to_commits(), which fills the commits list with the distinct commits from the oids list. During this loop, it also counts the number of "extra" edges from octopus merges. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract count_distinct_commits()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. Extract count_distinct_commits(), which sorts the oids list, then iterates through to find duplicates. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract fill_oids_from_all_packs()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. Extract fill_oids_from_all_packs() that reads all pack-files for commits and fills the oid list in the context. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract fill_oids_from_commit_hex()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. Extract fill_oids_from_commit_hex() that reads the given commit id list and fille the oid list in the context. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: extract fill_oids_from_packs()Derrick Stolee
The write_commit_graph() method is too complex, so we are extracting helper functions one by one. This extracts fill_oids_from_packs() that reads the given pack-file list and fills the oid list in the context. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: create write_commit_graph_contextDerrick Stolee
The write_commit_graph() method is too large and complex. To simplify it, we should extract several helper functions. However, we will risk repeating a lot of declarations related to progress incidators and object id or commit lists. Create a new write_commit_graph_context struct that contains the core data structures used in this process. Replace the other local variables with the values inside the context object. Following this change, we will start to lift code segments wholesale out of the write_commit_graph() method and into helper functions. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-12commit-graph: collapse parameters into flagsDerrick Stolee
The write_commit_graph() and write_commit_graph_reachable() methods currently take two boolean parameters: 'append' and 'report_progress'. As we update these methods, adding more parameters this way becomes cluttered and hard to maintain. Collapse these parameters into a 'flags' parameter, and adjust the callers to provide flags as necessary. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>