aboutsummaryrefslogtreecommitdiffstats
path: root/refs/refs-internal.h (follow)
AgeCommit message (Collapse)AuthorFilesLines
2025-09-19refs: add a generic 'optimize' APIMeet Soni1-0/+3
The existing `pack-refs` API is conceptually tied to the 'files' backend, but its behavior is generic (e.g., it triggers compaction for reftable). This naming is confusing. Introduce a new generic refs_optimize() API that dispatches to a backend-specific implementation via a new 'optimize' vtable method. This lays the architectural groundwork for different reference backends (like 'files' and 'reftable') to provide their own storage optimization logic, which will be called from a single, generic entry point. Mentored-by: Patrick Steinhardt <ps@pks.im> Mentored-by: shejialuo <shejialuo@gmail.com> Signed-off-by: Meet Soni <meetsoni3017@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-08-21Merge branch 'ps/reflog-migrate-fixes'Junio C Hamano1-1/+2
"git refs migrate" to migrate the reflog entries from a refs backend to another had a handful of bugs squashed. * ps/reflog-migrate-fixes: refs: fix invalid old object IDs when migrating reflogs refs: stop unsetting REF_HAVE_OLD for log-only updates refs/files: detect race when generating reflog entry for HEAD refs: fix identity for migrated reflogs ident: fix type of string length parameter builtin/reflog: implement subcommand to write new entries refs: export `ref_transaction_update_reflog()` builtin/reflog: improve grouping of subcommands Documentation/git-reflog: convert to use synopsis type
2025-08-06refs: stop unsetting REF_HAVE_OLD for log-only updatesPatrick Steinhardt1-1/+2
The `REF_HAVE_OLD` flag indicates whether a given ref update has its old object ID set. If so, the value of that field is used to verify whether the current state of the reference matches this expected state. It is thus an important part of mitigating races with a concurrent process that updates the same set of references. When writing reflogs though we explicitly unset that flag. This is a sensible thing to do: the old state of reflog entry updates may not necessarily match the current on-disk state of its accompanying ref, but it's only intended to signal what old object ID we want to write into the new reflog entry. For example when migrating refs we end up writing many reflog entries for a single reference, and most likely those reflog entries will have many different old object IDs. But unsetting this flag also removes a useful signal, namely that the caller _did_ provide an old object ID for a given reflog entry. This signal will become useful in a subsequent commit, where we add a new flag that tells the transaction to use the provided old and new object IDs to write a reflog entry. The `REF_HAVE_OLD` flag is then used as a signal to verify that the caller really did provide an old object ID. Stop unsetting the flag so that we can use it as this described signal in a subsequent commit. Skip checking the old object ID for log-only updates so that we don't expect it to match the current on-disk state. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-07-15refs: selectively set prefix in the seek functionsKarthik Nayak1-3/+4
The ref iterator exposes a `ref_iterator_seek()` function. The name suggests that this would seek the iterator to a specific reference in some ways similar to how `fseek()` works for the filesystem. However, the function actually sets the prefix for refs iteration. So further iteration would only yield references which match the particular prefix. This is a bit confusing. Let's add a 'flags' field to the function, which when set with the 'REF_ITERATOR_SEEK_SET_PREFIX' flag, will set the prefix for the iteration in-line with the existing behavior. Otherwise, the reference backends will simply seek to the specified reference and clears any previously set prefix. This allows users to start iteration from a specific reference. In the packed and reftable backend, since references are available in a sorted list, the changes are simply setting the prefix if needed. The changes on the files-backend are a little more involved, since the files backend uses the 'ref-cache' mechanism. We move out the existing logic within `cache_ref_iterator_seek()` to `cache_ref_iterator_set_prefix()` which is called when the 'REF_ITERATOR_SEEK_SET_PREFIX' flag is set. We then parse the provided seek string and set the required levels and their indexes to ensure that seeking is possible. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-07-15refs: expose `ref_iterator` via 'refs.h'Karthik Nayak1-143/+2
The `ref_iterator` is an internal structure to the 'refs/' sub-directory, which allows iteration over refs. All reference iteration is built on top of these iterators. External clients of the 'refs' subsystem use the various 'refs_for_each...()' functions to iterate over refs. However since these are wrapper functions, each combination of functionality requires a new wrapper function. This is not feasible as the functions pile up with the increase in requirements. Expose the internal reference iterator, so advanced users can mix and match options as needed. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-08refs: support rejection in batch updates during F/D checksKarthik Nayak1-0/+16
The `refs_verify_refnames_available()` is used to batch check refnames for F/D conflicts. While this is the more performant alternative than its individual version, it does not provide rejection capabilities on a single update level. For batched updates, this would mean a rejection of the entire transaction whenever one reference has a F/D conflict. Modify the function to call `ref_transaction_maybe_set_rejected()` to check if a single update can be rejected. Since this function is only internally used within 'refs/' and we want to pass in a `struct ref_transaction *` as a variable. We also move and mark `refs_verify_refnames_available()` to 'refs-internal.h' to be an internal function. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Acked-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-08refs: implement batch reference update supportKarthik Nayak1-0/+26
Git supports making reference updates with or without transactions. Updates with transactions are generally better optimized. But transactions are all or nothing. This means, if a user wants to batch updates to take advantage of the optimizations without the hard requirement that all updates must succeed, there is no way currently to do so. Particularly with the reftable backend where batching multiple reference updates is more efficient than performing them sequentially. Introduce batched update support with a new flag, 'REF_TRANSACTION_ALLOW_FAILURE'. Batched updates while different from transactions, use the transaction infrastructure under the hood. When enabled, this flag allows individual reference updates that would typically cause the entire transaction to fail due to non-system-related errors to be marked as rejected while permitting other updates to proceed. System errors referred by 'REF_TRANSACTION_ERROR_GENERIC' continue to result in the entire transaction failing. This approach enhances flexibility while preserving transactional integrity where necessary. The implementation introduces several key components: - Add 'rejection_err' field to struct `ref_update` to track failed updates with failure reason. - Add a new struct `ref_transaction_rejections` and a field within `ref_transaction` to this struct to allow quick iteration over rejected updates. - Modify reference backends (files, packed, reftable) to handle partial transactions by using `ref_transaction_set_rejected()` instead of failing the entire transaction when `REF_TRANSACTION_ALLOW_FAILURE` is set. - Add `ref_transaction_for_each_rejected_update()` to let callers examine which updates were rejected and why. This foundational change enables batched update support throughout the reference subsystem. A following commit will expose this capability to users by adding a `--batch-updates` flag to 'git-update-ref(1)', providing both a user-facing feature and a testable implementation. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Acked-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-08refs: introduce enum-based transaction error typesKarthik Nayak1-2/+3
Replace preprocessor-defined transaction errors with a strongly-typed enum `ref_transaction_error`. This change: - Improves type safety and function signature clarity. - Makes error handling more explicit and discoverable. - Maintains existing error cases, while adding new error cases for common scenarios. This refactoring paves the way for more comprehensive error handling which we will utilize in the upcoming commits to add batch reference update support. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Acked-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-08refs/files: remove duplicate duplicates checkKarthik Nayak1-8/+0
Within the files reference backend's transaction's 'finish' phase, a verification step is currently performed wherein the refnames list is sorted and examined for multiple updates targeting the same refname. It has been observed that this verification is redundant, as an identical check is already executed during the transaction's 'prepare' stage. Since the refnames list remains unmodified following the 'prepare' stage, this secondary verification can be safely eliminated. The duplicate check has been removed accordingly, and the `ref_update_reject_duplicates()` function has been marked as static, as its usage is now confined to 'refs.c'. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Acked-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-08refs: move duplicate refname update check to generic layerKarthik Nayak1-0/+2
Move the tracking of refnames in `affected_refnames` from individual backends into the generic layer in 'refs.c'. This centralizes the duplicate refname detection that was previously handled separately by each backend. Make some changes to accommodate this move: - Add a `string_list` field `refnames` to `ref_transaction` to contain all the references in a transaction. This field is updated whenever a new update is added via `ref_transaction_add_update`, so manual additions in reference backends are dropped. - Modify the backends to use this field internally as needed. The backends need to check if an update for refname already exists when splitting symrefs or adding an update for 'HEAD'. - In the reftable backend, within `reftable_be_transaction_prepare()`, move the `string_list_has_string()` check above `ref_transaction_add_update()`. Since `ref_transaction_add_update()` automatically adds the refname to `transaction->refnames`, performing the check after will always return true, so we perform the check before adding the update. This helps reduce duplication of functionality between the backends and makes it easier to make changes in a more centralized manner. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Acked-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-03-12refs/iterator: provide infrastructure to re-seek iteratorsPatrick Steinhardt1-0/+24
Reftable iterators need to be scrapped after they have either been exhausted or aren't useful to the caller anymore, and it is explicitly not possible to reuse them for iterations. But enabling for reuse of iterators may allow us to tune them by reusing internal state of an iterator. The reftable iterators for example can already be reused internally, but we're not able to expose this to any users outside of the reftable backend. Introduce a new `.seek` function in the ref iterator vtable that allows callers to seek an iterator multiple times. It is expected to be functionally the same as calling `refs_ref_iterator_begin()` with a different (or the same) prefix. Note that it is not possible to adjust parameters other than the seeked prefix for now, so exclude patterns, trimmed prefixes and flags will remain unchanged. We do not have a usecase for changing these parameters right now, but if we ever find one we can adapt accordingly. Implement the callback for trivial cases. The other iterators will be implemented in subsequent commits. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-03-12refs/iterator: separate lifecycle from iterationPatrick Steinhardt1-20/+9
The ref and reflog iterators have their lifecycle attached to iteration: once the iterator reaches its end, it is automatically released and the caller doesn't have to care about that anymore. When the iterator should be released before it has been exhausted, callers must explicitly abort the iterator via `ref_iterator_abort()`. This lifecycle is somewhat unusual in the Git codebase and creates two problems: - Callsites need to be very careful about when exactly they call `ref_iterator_abort()`, as calling the function is only valid when the iterator itself still is. This leads to somewhat awkward calling patterns in some situations. - It is impossible to reuse iterators and re-seek them to a different prefix. This feature isn't supported by any iterator implementation except for the reftable iterators anyway, but if it was implemented it would allow us to optimize cases where we need to search for specific references repeatedly by reusing internal state. Detangle the lifecycle from iteration so that we don't deallocate the iterator anymore once it is exhausted. Instead, callers are now expected to always call a newly introduce `ref_iterator_free()` function that deallocates the iterator and its internal state. Note that the `dir_iterator` is somewhat special because it does not implement the `ref_iterator` interface, but is only used to implement other iterators. Consequently, we have to provide `dir_iterator_free()` instead of `dir_iterator_release()` as the allocated structure itself is managed by the `dir_iterator` interfaces, as well, and not freed by `ref_iterator_free()` like in all the other cases. While at it, drop the return value of `ref_iterator_abort()`, which wasn't really required by any of the iterator implementations anyway. Furthermore, stop calling `base_ref_iterator_free()` in any of the backends, but instead call it in `ref_iterator_free()`. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-22refs: use 'uint64_t' for 'ref_update.index'Karthik Nayak1-2/+2
The 'ref_update.index' variable is used to store an index for a given reference update. This index is used to order the updates in a predetermined order, while the default ordering is alphabetical as per the refname. For large repositories with millions of references, it should be safer to use 'uint64_t'. Let's do that. This also is applied for all other code sections where we store 'index' and pass it around. Reported-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-17Merge branch 'kn/reflog-migration-fix' into kn/reflog-migration-fix-followupJunio C Hamano1-0/+1
* kn/reflog-migration-fix: reftable: write correct max_update_index to header
2025-01-15reftable: write correct max_update_index to headerKarthik Nayak1-0/+1
In 297c09eabb (refs: allow multiple reflog entries for the same refname, 2024-12-16), the reftable backend learned to handle multiple reflog entries within the same transaction. This was done modifying the `update_index` for reflogs with multiple indices. During writing the logs, the `max_update_index` of the writer was modified to ensure the limits were raised to the modified `update_index`s. However, since ref entries are written before the modification to the `max_update_index`, if there are multiple blocks to be written, the reftable backend writes the header with the old `max_update_index`. When all logs are finally written, the footer will be written with the new `min_update_index`. This causes a mismatch between the header and the footer and causes the reftable file to be corrupted. The existing tests only spawn a single block and since headers are lazily written with the first block, the tests didn't capture this bug. To fix the issue, the appropriate `max_update_index` limit must be set even before the first block is written. Add a `max_index` field to the transaction which holds the `max_index` within all its updates, then propagate this value to the reftable backend, wherein this is used to the set the `max_update_index` correctly. Add a test which creates a few thousand reference updates with multiple reflog entries, which should trigger the bug. Reported-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-23Merge branch 'kn/reflog-migration'Junio C Hamano1-0/+9
"git refs migrate" learned to also migrate the reflog data across backends. * kn/reflog-migration: refs: mark invalid refname message for translation refs: add support for migrating reflogs refs: allow multiple reflog entries for the same refname refs: introduce the `ref_transaction_update_reflog` function refs: add `committer_info` to `ref_transaction_add_update()` refs: extract out refname verification in transactions refs/files: add count field to ref_lock refs: add `index` field to `struct ref_udpate` refs: include committer info in `ref_update` struct
2024-12-19Merge branch 'bf/set-head-symref'Junio C Hamano1-0/+5
When "git fetch $remote" notices that refs/remotes/$remote/HEAD is missing and discovers what branch the other side points with its HEAD, refs/remotes/$remote/HEAD is updated to point to it. * bf/set-head-symref: fetch set_head: handle mirrored bare repositories fetch: set remote/HEAD if it does not exist refs: add create_only option to refs_update_symref_extended refs: add TRANSACTION_CREATE_EXISTS error remote set-head: better output for --auto remote set-head: refactor for readability refs: atomically record overwritten ref in update_symref refs: standardize output of refs_read_symbolic_ref t/t5505-remote: test failure of set-head t/t5505-remote: set default branch to main
2024-12-16refs: add `committer_info` to `ref_transaction_add_update()`Karthik Nayak1-0/+1
The `ref_transaction_add_update()` creates the `ref_update` struct. To facilitate addition of reflogs in the next commit, the function needs to accommodate setting the `committer_info` field in the struct. So modify the function to also take `committer_info` as an argument and set it accordingly. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-16refs: add `index` field to `struct ref_udpate`Karthik Nayak1-0/+7
The reftable backend, sorts its updates by refname before applying them, this ensures that the references are stored sorted. When migrating reflogs from one backend to another, the order of the reflogs must be maintained. Add a new `index` field to the `ref_update` struct to facilitate this. This field is used in the reftable backend's sort comparison function `transaction_update_cmp`, to ensure that indexed fields maintain their order. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-16refs: include committer info in `ref_update` structKarthik Nayak1-0/+1
The reference backends obtain the committer information from `git_committer_info(0)` when adding a reflog. The upcoming patches introduce support for migrating reflogs between the reference backends. This requires an interface to creating reflogs, including custom committer information. Add a new field `committer_info` to the `ref_update` struct, which is then used by the reference backends. If there is no `committer_info` provided, the reference backends default to using `git_committer_info(0)`. The field itself cannot be set to `git_committer_info(0)` since the values are dynamic and must be obtained right when the reflog is being committed. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-04Merge branch 'sj/ref-contents-check'Junio C Hamano1-2/+3
"git fsck" learned to issue warnings on "curiously formatted" ref contents that have always been taken valid but something Git wouldn't have written itself (e.g., missing terminating end-of-line after the full object name). * sj/ref-contents-check: ref: add symlink ref content check for files backend ref: check whether the target of the symref is a ref ref: add basic symref content check for files backend ref: add more strict checks for regular refs ref: port git-fsck(1) regular refs check for files backend ref: support multiple worktrees check for refs ref: initialize ref name outside of check functions ref: check the full refname instead of basename ref: initialize "fsck_ref_report" with zero
2024-11-25refs: standardize output of refs_read_symbolic_refBence Ferdinandy1-0/+5
When the symbolic reference we want to read with refs_read_symbolic_ref is actually not a symbolic reference, the files and the reftable backends return different values (1 and -1 respectively). Standardize the returned values so that 0 is success, -1 is a generic error and -2 is that the reference was actually non-symbolic. Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21ref: add more strict checks for regular refsshejialuo1-1/+1
We have already used "parse_loose_ref_contents" function to check whether the ref content is valid in files backend. However, by using "parse_loose_ref_contents", we allow the ref's content to end with garbage or without a newline. Even though we never create such loose refs ourselves, we have accepted such loose refs. So, it is entirely possible that some third-party tools may rely on such loose refs being valid. We should not report an error fsck message at current. We should notify the users about such "curiously formatted" loose refs so that adequate care is taken before we decide to tighten the rules in the future. And it's not suitable either to report a warn fsck message to the user. We don't yet want the "--strict" flag that controls this bit to end up generating errors for such weirdly-formatted reference contents, as we first want to assess whether this retroactive tightening will cause issues for any tools out there. It may cause compatibility issues which may break the repository. So, we add the following two fsck infos to represent the situation where the ref content ends without newline or has trailing garbages: 1. refMissingNewline(INFO): A loose ref that does not end with newline(LF). 2. trailingRefContent(INFO): A loose ref has trailing content. It might appear that we can't provide the user with any warnings by using FSCK_INFO. However, in "fsck.c::fsck_vreport", we will convert FSCK_INFO to FSCK_WARN and we can still warn the user about these situations when using "git refs verify" without introducing compatibility issues. Mentored-by: Patrick Steinhardt <ps@pks.im> Mentored-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: shejialuo <shejialuo@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21ref: support multiple worktrees check for refsshejialuo1-1/+2
We have already set up the infrastructure to check the consistency for refs, but we do not support multiple worktrees. However, "git-fsck(1)" will check the refs of worktrees. As we decide to get feature parity with "git-fsck(1)", we need to set up support for multiple worktrees. Because each worktree has its own specific refs, instead of just showing the users "refs/worktree/foo", we need to display the full name such as "worktrees/<id>/refs/worktree/foo". So we should know the id of the worktree to get the full name. Add a new parameter "struct worktree *" for "refs-internal.h::fsck_fn". Then change the related functions to follow this new interface. The "packed-refs" only exists in the main worktree, so we should only check "packed-refs" in the main worktree. Use "is_main_worktree" method to skip checking "packed-refs" in "packed_fsck" function. Then, enhance the "files-backend.c::files_fsck_refs_dir" function to add "worktree/<id>/" prefix when we are not in the main worktree. Last, add a new test to check the refname when there are multiple worktrees to exercise the code. Mentored-by: Patrick Steinhardt <ps@pks.im> Mentored-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: shejialuo <shejialuo@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21refs: introduce "initial" transaction flagPatrick Steinhardt1-1/+0
There are two different ways to commit a transaction: - `ref_transaction_commit()` can be used to commit a regular transaction and is what almost every caller wants. - `initial_ref_transaction_commit()` can be used when it is known that the ref store that the transaction is committed for is empty and when there are no concurrent processes. This is used when cloning a new repository. Implementing this via two separate functions has a couple of downsides. First, every reference backend needs to implement a separate callback even in the case where they don't special-case the initial transaction. Second, backends are basically forced to reimplement the whole logic for how to commit the transaction like the "files" backend does, even though backends may wish to only tweak certain behaviour of a "normal" commit. Third, it is awkward that callers must never prepare the transaction as this is somewhat different than how a transaction typically works. Refactor the code such that we instead mark initial transactions via a separate flag when starting the transaction. This addresses all of the mentioned painpoints, where the most important part is that it will allow backends to have way more leeway in how exactly they want to handle the initial transaction. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21refs: allow passing flags when setting up a transactionPatrick Steinhardt1-0/+1
Allow passing flags when setting up a transaction such that the behaviour of the transaction itself can be altered. This functionality will be used in a subsequent patch. Adapt callers accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-16Merge branch 'sj/ref-fsck'Junio C Hamano1-0/+6
"git fsck" infrastructure has been taught to also check the sanity of the ref database, in addition to the object database. * sj/ref-fsck: fsck: add ref name check for files backend files-backend: add unified interface for refs scanning builtin/refs: add verify subcommand refs: set up ref consistency check infrastructure fsck: add refs report function fsck: add a unified interface for reporting fsck messages fsck: make "fsck_error" callback generic fsck: rename objects-related fsck error functions fsck: rename "skiplist" to "skip_oids"
2024-08-15Merge branch 'jc/refs-symref-referent'Junio C Hamano1-0/+1
The refs API has been taught to give symref target information to the users of ref iterators, allowing for-each-ref and friends to avoid an extra ref_resolve_* API call per a symbolic ref. * jc/refs-symref-referent: ref-filter: populate symref from iterator refs: add referent to each_ref_fn refs: keep track of unresolved reference value in iterators
2024-08-09refs: keep track of unresolved reference value in iteratorsJohn Cai1-0/+1
Since ref iterators do not hold onto the direct value of a reference without resolving it, the only way to get ahold of a direct value of a symbolic ref is to make a separate call to refs_read_symbolic_ref. To make accessing the direct value of a symbolic ref more efficient, let's save the direct value of the ref in the iterators for both the files backend and the reftable backend. Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-08refs: set up ref consistency check infrastructureshejialuo1-0/+6
The "struct ref_store" is the base class which contains the "be" pointer which provides backend-specific functions whose interfaces are defined in the "ref_storage_be". We could reuse this polymorphism to define only one interface. For every backend, we need to provide its own function pointer. The interfaces defined in the `ref_storage_be` are carefully structured in semantic. It's organized as the five parts: 1. The name and the initialization interfaces. 2. The ref transaction interfaces. 3. The ref internal interfaces (pack, rename and copy). 4. The ref filesystem interfaces. 5. The reflog related interfaces. To keep consistent with the git-fsck(1), add a new interface named "fsck_refs_fn" to the end of "ref_storage_be". This semantic cannot be grouped into any above five categories. Explicitly add blank line to make it different from others. Last, implement placeholder functions for each ref backends. Mentored-by: Patrick Steinhardt <ps@pks.im> Mentored-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: shejialuo <shejialuo@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-07-30refs/files: stop using `the_repository` in `parse_loose_ref_contents()`Patrick Steinhardt1-1/+2
We implicitly rely on `the_repository` in `parse_loose_ref_contents()` by calling `parse_oid_hex()`. Convert the function to instead use `parse_oid_hex_algop()` and have callers pass in the hash algorithm to use. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-20Merge branch 'kn/update-ref-symref'Junio C Hamano1-0/+6
"git update-ref --stdin" learned to handle transactional updates of symbolic-refs. * kn/update-ref-symref: update-ref: add support for 'symref-update' command reftable: pick either 'oid' or 'target' for new updates update-ref: add support for 'symref-create' command update-ref: add support for 'symref-delete' command update-ref: add support for 'symref-verify' command refs: specify error for regular refs with `old_target` refs: create and use `ref_update_expects_existing_old_ref()`
2024-06-07refs: create and use `ref_update_expects_existing_old_ref()`Karthik Nayak1-0/+6
The files and reftable backend, need to check if a ref must exist, so that the required validation can be done. A ref must exist only when the `old_oid` value of the update has been explicitly set and it is not the `null_oid` value. Since we also support symrefs now, we need to ensure that even when `old_target` is set a ref must exist. While this was missed when we added symref support in transactions, there are no active users of this path. As we introduce the 'symref-verify' command in the upcoming commits, it is important to fix this. So let's export this to a function called `ref_update_expects_existing_old_ref()` and expose it internally via 'refs-internal.h'. Helped-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-06refs: implement removal of ref storagesPatrick Steinhardt1-0/+7
We're about to introduce logic to migrate ref storages. One part of the migration will be to delete the files that are part of the old ref storage format. We don't yet have a way to delete such data generically across ref backends though. Implement a new `delete` callback and expose it via a new `ref_storage_delete()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-23Merge branch 'ps/refs-without-the-repository-updates' into ↵Junio C Hamano1-42/+12
ps/ref-storage-migration * ps/refs-without-the-repository-updates: refs/packed: remove references to `the_hash_algo` refs/files: remove references to `the_hash_algo` refs/files: use correct repository refs: remove `dwim_log()` refs: drop `git_default_branch_name()` refs: pass repo when peeling objects refs: move object peeling into "object.c" refs: pass ref store when detecting dangling symrefs refs: convert iteration over replace refs to accept ref store refs: retrieve worktree ref stores via associated repository refs: refactor `resolve_gitlink_ref()` to accept a repository refs: pass repo when retrieving submodule ref store refs: track ref stores via strmap refs: implement releasing ref storages refs: rename `init_db` callback to avoid confusion refs: adjust names for `init` and `init_db` callbacks
2024-05-17refs: move object peeling into "object.c"Patrick Steinhardt1-34/+0
Peeling an object has nothing to do with refs, but we still have the code in "refs.c". Move it over into "object.c", which is a more natural place to put it. Ideally, we'd also move `peel_iterated_oid()` over into "object.c". But this function is tied to the refs interfaces because it uses a global ref iterator variable to optimize peeling when the iterator already has the peeled object ID readily available. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: convert iteration over replace refs to accept ref storePatrick Steinhardt1-3/+2
The function `for_each_replace_ref()` is a bit of an oddball across the refs interfaces as it accepts a pointer to the repository instead of a pointer to the ref store. The only reason for us to accept a repository is so that we can eventually pass it back to the callback function that the caller has provided. This is somewhat arbitrary though, as callers that need the repository can instead make it accessible via the callback payload. Refactor the function to instead accept the ref store and adjust callers accordingly. This allows us to get rid of some of the boilerplate that we had to carry to pass along the repository and brings us in line with the other functions that iterate through refs. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: pass repo when retrieving submodule ref storePatrick Steinhardt1-1/+1
Looking up submodule ref stores has two deficiencies: - The initialized subrepo will be attributed to `the_repository`. - The submodule ref store will be tracked in a global map. This makes it impossible to have submodule ref stores for a repository other than `the_repository`. Modify the function to accept the parent repository as parameter and move the global map into `struct repository`. Like this it becomes possible to look up submodule ref stores for arbitrary repositories. Note that this also adds a new reference to `the_repository` in `resolve_gitlink_ref()`, which is part of the refs interfaces. This will get adjusted in the next patch. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: implement releasing ref storagesPatrick Steinhardt1-0/+5
Ref storages are typically only initialized once for `the_repository` and then never released. Until now we got away with that without causing memory leaks because `the_repository` stays reachable, and because the ref backend is reachable via `the_repository` its memory basically never leaks. This is about to change though because of the upcoming migration logic, which will create a secondary ref storage. In that case, we will either have to release the old or new ref storage to avoid leaks. Implement a new `release` callback and expose it via a new `ref_storage_release()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-17refs: rename `init_db` callback to avoid confusionPatrick Steinhardt1-4/+4
Reference backends have two callbacks `init` and `init_db`. The similarity of these two callbacks has repeatedly confused me whenever I was looking at them, where I always had to look up which of them does what. Rename the `init_db` callback to `create_on_disk`, which should hopefully be clearer. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: remove `create_symref` and associated dead codeKarthik Nayak1-5/+0
In the previous commits, we converted `refs_create_symref()` to utilize transactions to perform symref updates. Earlier `refs_create_symref()` used `create_symref()` to do the same. We can now remove `create_symref()` and any code associated with it which is no longer used. We remove `create_symref()` code from all the reference backends and also remove it entirely from the `ref_storage_be` struct. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: add support for transactional symref updatesKarthik Nayak1-0/+16
The reference backends currently support transactional reference updates. While this is exposed to users via 'git-update-ref' and its '--stdin' mode, it is also used internally within various commands. However, we do not support transactional updates of symrefs. This commit adds support for symrefs in both the 'files' and the 'reftable' backend. Here, we add and use `ref_update_has_null_new_value()`, a helper function which is used to check if there is a new_value in a reference update. The new value could either be a symref target `new_target` or a OID `new_oid`. We also add another common function `ref_update_check_old_target` which will be used to check if the update's old_target corresponds to a reference's current target. Now transactional updates (verify, create, delete, update) can be used for: - regular refs - symbolic refs - conversion of regular to symbolic refs and vice versa This also allows us to expose this to users via new commands in 'git-update-ref' in the future. Note that a dangling symref update does not record a new reflog entry, which is unchanged before and after this commit. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: move `original_update_refname` to 'refs.c'Karthik Nayak1-0/+5
The files backend and the reftable backend implement `original_update_refname` to obtain the original refname of the update. Move it out to 'refs.c' and only expose it internally to the refs library. This will be used in an upcoming commit to also introduce another common functionality for the two backends. We also rename the function to `ref_update_original_update_refname` to keep it consistent with the upcoming other 'ref_update_*' functions that'll be introduced. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-07refs: accept symref values in `ref_transaction_update()`Karthik Nayak1-0/+14
The function `ref_transaction_update()` obtains ref information and flags to create a `ref_update` and add them to the transaction at hand. To extend symref support in transactions, we need to also accept the old and new ref targets and process it. This commit adds the required parameters to the function and modifies all call sites. The two parameters added are `new_target` and `old_target`. The `new_target` is used to denote what the reference should point to when the transaction is applied. Some functions allow this parameter to be NULL, meaning that the reference is not changed. The `old_target` denotes the value the reference must have before the update. Some functions allow this parameter to be NULL, meaning that the old value of the reference is not checked. We also update the internal function `ref_transaction_add_update()` similarly to take the two new parameters. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-03-05Merge branch 'kn/for-all-refs'Junio C Hamano1-0/+6
"git for-each-ref" learned "--include-root-refs" option to show even the stuff outside the 'refs/' hierarchy. * kn/for-all-refs: for-each-ref: add new option to include root refs ref-filter: rename 'FILTER_REFS_ALL' to 'FILTER_REFS_REGULAR' refs: introduce `refs_for_each_include_root_refs()` refs: extract out `loose_fill_ref_dir_regular_file()` refs: introduce `is_pseudoref()` and `is_headref()`
2024-02-23refs: introduce `refs_for_each_include_root_refs()`Karthik Nayak1-0/+6
Introduce a new ref iteration flag `DO_FOR_EACH_INCLUDE_ROOT_REFS`, which will be used to iterate over regular refs plus pseudorefs and HEAD. Refs which fall outside the `refs/` and aren't either pseudorefs or HEAD are more of a grey area. This is because we don't block the users from creating such refs but they are not officially supported. Introduce `refs_for_each_include_root_refs()` which calls `do_for_each_ref()` with this newly introduced flag. In `refs/files-backend.c`, introduce a new function `add_pseudoref_and_head_entries()` to add pseudorefs and HEAD to the `ref_dir`. We then finally call `add_pseudoref_and_head_entries()` whenever the `DO_FOR_EACH_INCLUDE_ROOT_REFS` flag is set. Any new ref backend will also have to implement similar changes on its end. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-21refs: always treat iterators as orderedPatrick Steinhardt1-16/+2
In the preceding commit we have converted the reflog iterator of the "files" backend to be ordered, which was the only remaining ref iterator that wasn't ordered. Refactor the ref iterator infrastructure so that we always assume iterators to be ordered, thus simplifying the code. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-21refs/files: sort merged worktree and common reflogsPatrick Steinhardt1-0/+9
When iterating through reflogs in a worktree we create a merged iterator that merges reflogs from both refdbs. The resulting refs are ordered so that instead we first return all worktree reflogs before we return all common refs. This is the only remaining case where a ref iterator returns entries in a non-lexicographic order. The result would look something like the following (listed with a command we introduce in a subsequent commit): ``` $ git reflog list HEAD refs/worktree/per-worktree refs/heads/main refs/heads/wt ``` So we first print the per-worktree reflogs in lexicographic order, then the common reflogs in lexicographic order. This is confusing and not consistent with how we print per-worktree refs, which are exclusively sorted lexicographically. Sort reflogs lexicographically in the same way as we sort normal refs. As this is already implemented properly by the "reftable" backend via a separate selection function, we simply pull out that logic and reuse it for the "files" backend. As logs are properly sorted now, mark the merged reflog iterator as sorted. Tests will be added in a subsequent commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-07refs: introduce reftable backendPatrick Steinhardt1-0/+1
Due to scalability issues, Shawn Pearce has originally proposed a new "reftable" format more than six years ago [1]. Initially, this new format was implemented in JGit with promising results. Around two years ago, we have then added the "reftable" library to the Git codebase via a4bbd13be3 (Merge branch 'hn/reftable', 2021-12-15). With this we have landed all the low-level code to read and write reftables. Notably missing though was the integration of this low-level code into the Git code base in the form of a new ref backend that ties all of this together. This gap is now finally closed by introducing a new "reftable" backend into the Git codebase. This new backend promises to bring some notable improvements to Git repositories: - It becomes possible to do truly atomic writes where either all refs are committed to disk or none are. This was not possible with the "files" backend because ref updates were split across multiple loose files. - The disk space required to store many refs is reduced, both compared to loose refs and packed-refs. This is enabled both by the reftable format being a binary format, which is more compact, and by prefix compression. - We can ignore filesystem-specific behaviour as ref names are not encoded via paths anymore. This means there is no need to handle case sensitivity on Windows systems or Unicode precomposition on macOS. - There is no need to rewrite the complete refdb anymore every time a ref is being deleted like it was the case for packed-refs. This means that ref deletions are now constant time instead of scaling linearly with the number of refs. - We can ignore file/directory conflicts so that it becomes possible to store both "refs/heads/foo" and "refs/heads/foo/bar". - Due to this property we can retain reflogs for deleted refs. We have previously been deleting reflogs together with their refs to avoid file/directory conflicts, which is not necessary anymore. - We can properly enumerate all refs. With the "files" backend it is not easily possible to distinguish between refs and non-refs because they may live side by side in the gitdir. Not all of these improvements are realized with the current "reftable" backend implementation. At this point, the new backend is supposed to be a drop-in replacement for the "files" backend that is used by basically all Git repositories nowadays. It strives for 1:1 compatibility, which means that a user can expect the same behaviour regardless of whether they use the "reftable" backend or the "files" backend for most of the part. Most notably, this means we artificially limit the capabilities of the "reftable" backend to match the limits of the "files" backend. It is not possible to create refs that would end up with file/directory conflicts, we do not retain reflogs, we perform stricter-than-necessary checks. This is done intentionally due to two main reasons: - It makes it significantly easier to land the "reftable" backend as tests behave the same. It would be tough to argue for each and every single test that doesn't pass with the "reftable" backend. - It ensures compatibility between repositories that use the "files" backend and repositories that use the "reftable" backend. Like this, hosters can migrate their repositories to use the "reftable" backend without causing issues for clients that use the "files" backend in their clones. It is expected that these artificial limitations may eventually go away in the long term. Performance-wise things very much depend on the actual workload. The following benchmarks compare the "files" and "reftable" backends in the current version: - Creating N refs in separate transactions shows that the "files" backend is ~50% faster. This is not surprising given that creating a ref only requires us to create a single loose ref. The "reftable" backend will also perform auto compaction on updates. In real-world workloads we would likely also want to perform pack loose refs, which would likely change the picture. Benchmark 1: update-ref: create refs sequentially (refformat = files, refcount = 1) Time (mean ± σ): 2.1 ms ± 0.3 ms [User: 0.6 ms, System: 1.7 ms] Range (min … max): 1.8 ms … 4.3 ms 133 runs Benchmark 2: update-ref: create refs sequentially (refformat = reftable, refcount = 1) Time (mean ± σ): 2.7 ms ± 0.1 ms [User: 0.6 ms, System: 2.2 ms] Range (min … max): 2.4 ms … 2.9 ms 132 runs Benchmark 3: update-ref: create refs sequentially (refformat = files, refcount = 1000) Time (mean ± σ): 1.975 s ± 0.006 s [User: 0.437 s, System: 1.535 s] Range (min … max): 1.969 s … 1.980 s 3 runs Benchmark 4: update-ref: create refs sequentially (refformat = reftable, refcount = 1000) Time (mean ± σ): 2.611 s ± 0.013 s [User: 0.782 s, System: 1.825 s] Range (min … max): 2.597 s … 2.622 s 3 runs Benchmark 5: update-ref: create refs sequentially (refformat = files, refcount = 100000) Time (mean ± σ): 198.442 s ± 0.241 s [User: 43.051 s, System: 155.250 s] Range (min … max): 198.189 s … 198.670 s 3 runs Benchmark 6: update-ref: create refs sequentially (refformat = reftable, refcount = 100000) Time (mean ± σ): 294.509 s ± 4.269 s [User: 104.046 s, System: 190.326 s] Range (min … max): 290.223 s … 298.761 s 3 runs - Creating N refs in a single transaction shows that the "files" backend is significantly slower once we start to write many refs. The "reftable" backend only needs to update two files, whereas the "files" backend needs to write one file per ref. Benchmark 1: update-ref: create many refs (refformat = files, refcount = 1) Time (mean ± σ): 1.9 ms ± 0.1 ms [User: 0.4 ms, System: 1.4 ms] Range (min … max): 1.8 ms … 2.6 ms 151 runs Benchmark 2: update-ref: create many refs (refformat = reftable, refcount = 1) Time (mean ± σ): 2.5 ms ± 0.1 ms [User: 0.7 ms, System: 1.7 ms] Range (min … max): 2.4 ms … 3.4 ms 148 runs Benchmark 3: update-ref: create many refs (refformat = files, refcount = 1000) Time (mean ± σ): 152.5 ms ± 5.2 ms [User: 19.1 ms, System: 133.1 ms] Range (min … max): 148.5 ms … 167.8 ms 15 runs Benchmark 4: update-ref: create many refs (refformat = reftable, refcount = 1000) Time (mean ± σ): 58.0 ms ± 2.5 ms [User: 28.4 ms, System: 29.4 ms] Range (min … max): 56.3 ms … 72.9 ms 40 runs Benchmark 5: update-ref: create many refs (refformat = files, refcount = 1000000) Time (mean ± σ): 152.752 s ± 0.710 s [User: 20.315 s, System: 131.310 s] Range (min … max): 152.165 s … 153.542 s 3 runs Benchmark 6: update-ref: create many refs (refformat = reftable, refcount = 1000000) Time (mean ± σ): 51.912 s ± 0.127 s [User: 26.483 s, System: 25.424 s] Range (min … max): 51.769 s … 52.012 s 3 runs - Deleting a ref in a fully-packed repository shows that the "files" backend scales with the number of refs. The "reftable" backend has constant-time deletions. Benchmark 1: update-ref: delete ref (refformat = files, refcount = 1) Time (mean ± σ): 1.7 ms ± 0.1 ms [User: 0.4 ms, System: 1.2 ms] Range (min … max): 1.6 ms … 2.1 ms 316 runs Benchmark 2: update-ref: delete ref (refformat = reftable, refcount = 1) Time (mean ± σ): 1.8 ms ± 0.1 ms [User: 0.4 ms, System: 1.3 ms] Range (min … max): 1.7 ms … 2.1 ms 294 runs Benchmark 3: update-ref: delete ref (refformat = files, refcount = 1000) Time (mean ± σ): 2.0 ms ± 0.1 ms [User: 0.5 ms, System: 1.4 ms] Range (min … max): 1.9 ms … 2.5 ms 287 runs Benchmark 4: update-ref: delete ref (refformat = reftable, refcount = 1000) Time (mean ± σ): 1.9 ms ± 0.1 ms [User: 0.5 ms, System: 1.3 ms] Range (min … max): 1.8 ms … 2.1 ms 217 runs Benchmark 5: update-ref: delete ref (refformat = files, refcount = 1000000) Time (mean ± σ): 229.8 ms ± 7.9 ms [User: 182.6 ms, System: 46.8 ms] Range (min … max): 224.6 ms … 245.2 ms 6 runs Benchmark 6: update-ref: delete ref (refformat = reftable, refcount = 1000000) Time (mean ± σ): 2.0 ms ± 0.0 ms [User: 0.6 ms, System: 1.3 ms] Range (min … max): 2.0 ms … 2.1 ms 3 runs - Listing all refs shows no significant advantage for either of the backends. The "files" backend is a bit faster, but not by a significant margin. When repositories are not packed the "reftable" backend outperforms the "files" backend because the "reftable" backend performs auto-compaction. Benchmark 1: show-ref: print all refs (refformat = files, refcount = 1, packed = true) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 2.0 ms 1729 runs Benchmark 2: show-ref: print all refs (refformat = reftable, refcount = 1, packed = true) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 1.8 ms 1816 runs Benchmark 3: show-ref: print all refs (refformat = files, refcount = 1000, packed = true) Time (mean ± σ): 4.3 ms ± 0.1 ms [User: 0.9 ms, System: 3.3 ms] Range (min … max): 4.1 ms … 4.6 ms 645 runs Benchmark 4: show-ref: print all refs (refformat = reftable, refcount = 1000, packed = true) Time (mean ± σ): 4.5 ms ± 0.2 ms [User: 1.0 ms, System: 3.3 ms] Range (min … max): 4.2 ms … 5.9 ms 643 runs Benchmark 5: show-ref: print all refs (refformat = files, refcount = 1000000, packed = true) Time (mean ± σ): 2.537 s ± 0.034 s [User: 0.488 s, System: 2.048 s] Range (min … max): 2.511 s … 2.627 s 10 runs Benchmark 6: show-ref: print all refs (refformat = reftable, refcount = 1000000, packed = true) Time (mean ± σ): 2.712 s ± 0.017 s [User: 0.653 s, System: 2.059 s] Range (min … max): 2.692 s … 2.752 s 10 runs Benchmark 7: show-ref: print all refs (refformat = files, refcount = 1, packed = false) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 1.9 ms 1834 runs Benchmark 8: show-ref: print all refs (refformat = reftable, refcount = 1, packed = false) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.4 ms … 2.0 ms 1840 runs Benchmark 9: show-ref: print all refs (refformat = files, refcount = 1000, packed = false) Time (mean ± σ): 13.8 ms ± 0.2 ms [User: 2.8 ms, System: 10.8 ms] Range (min … max): 13.3 ms … 14.5 ms 208 runs Benchmark 10: show-ref: print all refs (refformat = reftable, refcount = 1000, packed = false) Time (mean ± σ): 4.5 ms ± 0.2 ms [User: 1.2 ms, System: 3.3 ms] Range (min … max): 4.3 ms … 6.2 ms 624 runs Benchmark 11: show-ref: print all refs (refformat = files, refcount = 1000000, packed = false) Time (mean ± σ): 12.127 s ± 0.129 s [User: 2.675 s, System: 9.451 s] Range (min … max): 11.965 s … 12.370 s 10 runs Benchmark 12: show-ref: print all refs (refformat = reftable, refcount = 1000000, packed = false) Time (mean ± σ): 2.799 s ± 0.022 s [User: 0.735 s, System: 2.063 s] Range (min … max): 2.769 s … 2.836 s 10 runs - Printing a single ref shows no real difference between the "files" and "reftable" backends. Benchmark 1: show-ref: print single ref (refformat = files, refcount = 1) Time (mean ± σ): 1.5 ms ± 0.1 ms [User: 0.4 ms, System: 1.0 ms] Range (min … max): 1.4 ms … 1.8 ms 1779 runs Benchmark 2: show-ref: print single ref (refformat = reftable, refcount = 1) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.4 ms … 2.5 ms 1753 runs Benchmark 3: show-ref: print single ref (refformat = files, refcount = 1000) Time (mean ± σ): 1.5 ms ± 0.1 ms [User: 0.3 ms, System: 1.1 ms] Range (min … max): 1.4 ms … 1.9 ms 1840 runs Benchmark 4: show-ref: print single ref (refformat = reftable, refcount = 1000) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 2.0 ms 1831 runs Benchmark 5: show-ref: print single ref (refformat = files, refcount = 1000000) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 2.1 ms 1848 runs Benchmark 6: show-ref: print single ref (refformat = reftable, refcount = 1000000) Time (mean ± σ): 1.6 ms ± 0.1 ms [User: 0.4 ms, System: 1.1 ms] Range (min … max): 1.5 ms … 2.1 ms 1762 runs So overall, performance depends on the usecases. Except for many sequential writes the "reftable" backend is roughly on par or significantly faster than the "files" backend though. Given that the "files" backend has received 18 years of optimizations by now this can be seen as a win. Furthermore, we can expect that the "reftable" backend will grow faster over time when attention turns more towards optimizations. The complete test suite passes, except for those tests explicitly marked to require the REFFILES prerequisite. Some tests in t0610 are marked as failing because they depend on still-in-flight bug fixes. Tests can be run with the new backend by setting the GIT_TEST_DEFAULT_REF_FORMAT environment variable to "reftable". There is a single known conceptual incompatibility with the dumb HTTP transport. As "info/refs" SHOULD NOT contain the HEAD reference, and because the "HEAD" file is not valid anymore, it is impossible for the remote client to figure out the default branch without changing the protocol. This shortcoming needs to be handled in a subsequent patch series. As the reftable library has already been introduced a while ago, this commit message will not go into the details of how exactly the on-disk format works. Please refer to our preexisting technical documentation at Documentation/technical/reftable for this. [1]: https://public-inbox.org/git/CAJo=hJtyof=HRy=2sLP0ng0uZ4=S-DpZ5dR1aF+VHVETKG20OQ@mail.gmail.com/ Original-idea-by: Shawn Pearce <spearce@spearce.org> Based-on-patch-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-01-08refs: prepare `refs_init_db()` for initializing worktree refsPatrick Steinhardt1-1/+3
The purpose of `refs_init_db()` is to initialize the on-disk files of a new ref database. The function is quite inflexible right now though, as callers can neither specify the `struct ref_store` nor can they pass any flags. Refactor the interface to accept both of these. This will be required so that we can start initializing per-worktree ref databases via the ref backend instead of open-coding the initialization in "worktree.c". Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>