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2025-04-07reftable/constants: make block types part of the public interfacePatrick Steinhardt1-5/+5
Now that reftable blocks can be read individually via the public interface it becomes necessary for callers to be able to distinguish the different types of blocks. Expose the relevant constants. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable/block: make block iterators reseekablePatrick Steinhardt1-1/+1
Refactor the block iterators so that initialization and seeking are different from one another. This makes the iterator trivially reseekable by storing the pointer to the block at initialization time, which we can then reuse on every seek. This refactoring prepares the code for exposing a `reftable_iterator` interface for blocks in a subsequent commit. Callsites are adjusted accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable/block: rename `block_reader` to `reftable_block`Patrick Steinhardt1-5/+4
The `block_reader` structure is used to access parsed data of a reftable block. The structure is currently treated as an internal implementation detail and not exposed via our public interfaces. The functionality provided by the structure is useful to external users of the reftable library though, for example when implementing consistency checks that need to scan through the blocks manually. Rename the structure to `reftable_block` now that the name has been made available in the preceding commit. This name is in line with the naming schema used for other data structures like `reftable_table` in that it describes the underlying entity that it provides access to. The new data structure isn't yet exposed via the public interface, which is left for a subsequent commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable/block: rename `block` to `block_data`Patrick Steinhardt1-2/+2
The `reftable_block` structure associates a byte slice with a block source. As such it only holds the data of a reftable block without actually encoding any of the details for how to access that data. Rename the structure to instead be called `reftable_block_data`. Besides clarifying that this really only holds data, it also allows us to rename the `reftable_block_reader` to `reftable_block` in the next commit, as this is the structure that actually encapsulates access to the reftable blocks. Rename the `struct reftable_block_reader::block` member accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable/blocksource: consolidate code into a single filePatrick Steinhardt1-2/+3
The code that implements block sources is distributed across a couple of files. Consolidate all of it into "reftable/blocksource.c" and its accompanying header so that it is easier to locate and more self contained. While at it, rename some of the functions to have properly scoped names. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable/reader: rename data structure to "table"Patrick Steinhardt1-5/+5
The `struct reftable_reader` subsystem encapsulates a table that has been read from the disk. As such, the current name of that structure is somewhat hard to understand as it only talks about the fact that we read something from disk, without really giving an indicator _what_ that is. Furthermore, this naming schema doesn't really fit well into how the other structures are named: `reftable_merged_table`, `reftable_stack`, `reftable_block` and `reftable_record` are all named after what they encapsulate. Rename the subsystem to `reftable_table`, which directly gives a hint that the data structure is about handling the individual tables part of the stack. While this change results in a lot of churn, it prepares for us exposing the APIs to third-party callers now that the reftable library is a standalone library that can be linked against by other projects. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-07reftable: fix formatting of the license headerPatrick Steinhardt1-6/+6
The license headers used across the reftable library doesn't follow our typical coding style for multi-line comments. Fix it. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18reftable/basics: introduce `REFTABLE_UNUSED` annotationPatrick Steinhardt1-5/+5
Introduce the `REFTABLE_UNUSED` annotation and replace all existing users of `UNUSED` in the reftable library to use the new macro instead. Note that we unconditionally define `MAYBE_UNUSED` in the exact same way, so doing so unconditionally for `REFTABLE_UNUSED` should be fine, too. Suggested-by: Toon Claes <toon@iotcl.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18reftable: stop using `BUG()` in trivial casesPatrick Steinhardt1-2/+1
Stop using `BUG()` in the remaining trivial cases that we still have in the reftable library. Instead of aborting the program, we'll now bubble up a `REFTABLE_API_ERROR` to indicate misuse of the calling conventions. Note that in both `reftable_reader_{inc,dec}ref()` we simply stop calling `BUG()` altogether. The only situation where the counter should be zero is when the structure has already been free'd anyway, so we would run into undefined behaviour regardless of whether we try to abort the program or not. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-17reftable: handle trivial `reftable_buf` errorsPatrick Steinhardt1-1/+4
Convert the reftable library such that we handle failures with the new `reftable_buf` interfaces. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-17reftable: convert from `strbuf` to `reftable_buf`Patrick Steinhardt1-3/+3
Convert the reftable library to use the `reftable_buf` interface instead of the `strbuf` interface. This is mostly a mechanical change via sed(1) with some manual fixes where functions for `strbuf` and `reftable_buf` differ. The converted code does not yet handle allocation failures. This will be handled in subsequent commits. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-10-02reftable: introduce `REFTABLE_FREE_AND_NULL()`Patrick Steinhardt1-1/+1
We have several calls to `FREE_AND_NULL()` in the reftable library, which of course uses free(3P). As the reftable allocators are pluggable we should rather call the reftable specific function, which is `reftable_free()`. Introduce a new macro `REFTABLE_FREE_AND_NULL()` and adapt the callsites accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-02reftable/iter: handle allocation failures when creating indexed table iterPatrick Steinhardt1-4/+16
Handle allocation failures in `new_indexed_table_ref_iter()`. While at it, rename the function to match our coding style. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-29Merge branch 'ps/reftable-drop-generic'Junio C Hamano1-21/+105
The code in the reftable library has been cleaned up by discarding unused "generic" interface. * ps/reftable-drop-generic: reftable: mark unused parameters in empty iterator functions reftable/generic: drop interface t/helper: refactor to not use `struct reftable_table` t/helper: use `hash_to_hex_algop()` to print hashes t/helper: inline printing of reftable records t/helper: inline `reftable_table_print()` t/helper: inline `reftable_stack_print_directory()` t/helper: inline `reftable_reader_print_file()` t/helper: inline `reftable_dump_main()` reftable/dump: drop unused `compact_stack()` reftable/generic: move generic iterator code into iterator interface reftable/iter: drop double-checking logic reftable/stack: open-code reading refs reftable/merged: stop using generic tables in the merged table reftable/merged: rename `reftable_new_merged_table()` reftable/merged: expose functions to initialize iterators
2024-08-28reftable: mark unused parameters in empty iterator functionsJeff King1-3/+3
These unused parameters were marked in a68ec8683a (reftable: mark unused parameters in virtual functions, 2024-08-17), but the functions were moved to a new file in a parallel branch via f2406c81b9 (reftable/generic: move generic iterator code into iterator interface, 2024-08-22). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-22reftable/generic: drop interfacePatrick Steinhardt1-1/+0
The `reftable_table` interface provides a generic infrastructure that can abstract away whether the underlying table is a single table, or a merged table. This abstraction can make it rather hard to reason about the code. We didn't ever use it to implement the reftable backend, and with the preceding patches in this patch series we in fact don't use it at all anymore. Furthermore, it became somewhat useless with the recent refactorings that made it possible to seek reftable iterators multiple times, as these now provide generic access to tables for us. The interface is thus redundant and only brings unnecessary complexity with it. Remove the `struct reftable_table` interface and its associated functions. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-22reftable/generic: move generic iterator code into iterator interfacePatrick Steinhardt1-0/+105
Move functions relating to the reftable iterator from "generic.c" into "iter.c". This prepares for the removal of the former subsystem. While at it, remove some unneeded braces to conform to our coding style. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-22reftable/iter: drop double-checking logicPatrick Steinhardt1-20/+0
The filtering ref iterator can be used to only yield refs which are not in a specific skip list. This iterator has an option to double-check the results it returns, which causes us to seek the reference we are about to yield via a separate table such that we detect whether the reference that the first iterator has yielded actually exists. The value of this is somewhat dubious, and I cannot think of any usecase where this functionality should be required. Furthermore, this option is never set in our codebase, which means that it is essentially untested. And last but not least, the `struct reftable_table` that is used to implement it is about to go away. So while we could refactor the code to not use a `reftable_table`, it very much feels like a wasted effort. Let's just drop this code. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-17reftable: mark unused parameters in virtual functionsJeff King1-1/+2
The reftable code uses a lot of virtual function pointers, but many of the concrete implementations do not need all of the parameters. For the most part these are obviously fine to just mark as UNUSED (e.g., the empty_iterator functions unsurprisingly do not do anything). Here are a few cases where I dug a little deeper (but still ended up just marking them UNUSED): - the iterator exclude_patterns is best-effort and optional (though it would be nice to support in the long run as an optimization) - ignoring the ref_store in many transaction functions is unexpected, but works because the ref_transaction itself carries enough information to do what we need. - ignoring "err" for in some cases (e.g., transaction abort) is OK because we do not return any errors. It is a little odd for reftable_be_create_reflog(), though, since we do return errors there. We should perhaps be creating string error messages at this layer, but I've punted on that for now. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-13reftable/generic: adapt interface to allow reuse of iteratorsPatrick Steinhardt1-4/+4
Refactor the interfaces exposed by `struct reftable_table` and `struct reftable_iterator` such that they support iterator reuse. This is done by separating initialization of the iterator and seeking on it. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-13reftable/generic: move seeking of records into the iteratorPatrick Steinhardt1-0/+15
Reftable iterators are created by seeking on the parent structure of a corresponding record. For example, to create an iterator for the merged table you would call `reftable_merged_table_seek_ref()`. Most notably, it is not posible to create an iterator and then seek it afterwards. While this may be a bit easier to reason about, it comes with two significant downsides. The first downside is that the logic to find records is split up between the parent data structure and the iterator itself. Conceptually, it is more straight forward if all that logic was contained in a single place, which should be the iterator. The second and more significant downside is that it is impossible to reuse iterators for multiple seeks. Whenever you want to look up a record, you need to re-create the whole infrastructure again, which is quite a waste of time. Furthermore, it is impossible to optimize seeks, such as when seeking the same record multiple times. To address this, we essentially split up the concerns properly such that the parent data structure is responsible for setting up the iterator via a new `init_iter()` callback, whereas the iterator handles seeks via a new `seek()` callback. This will eventually allow us to call `seek()` on the iterator multiple times, where every iterator can potentially optimize for certain cases. Note that at this point in time we are not yet ready to reuse the iterators. This will be left for a future patch series. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-04-15reftable/block: rename `block_reader_start()`Patrick Steinhardt1-1/+1
The function `block_reader_start()` does not really apply to the block reader, but to the block iterator. It's name is thus somewhat confusing. Rename it to `block_iter_seek_start()` to clarify. We will rename `block_reader_seek()` in similar spirit in the next commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-03-04reftable/merged: remove unnecessary null check for subitersPatrick Steinhardt1-5/+0
Whenever we advance a subiter we first call `iterator_is_null()`. This is not needed though because we only ever advance subiters which have entries in the priority queue, and we do not end entries to the priority queue when the subiter has been exhausted. Drop the check as well as the now-unused function. This results in a surprisingly big speedup: Benchmark 1: show-ref: single matching ref (revision = HEAD~) Time (mean ± σ): 138.1 ms ± 4.4 ms [User: 135.1 ms, System: 2.8 ms] Range (min … max): 133.4 ms … 167.3 ms 1000 runs Benchmark 2: show-ref: single matching ref (revision = HEAD) Time (mean ± σ): 134.4 ms ± 4.2 ms [User: 131.5 ms, System: 2.8 ms] Range (min … max): 130.0 ms … 164.0 ms 1000 runs Summary show-ref: single matching ref (revision = HEAD) ran 1.03 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~) Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-02-06reftable: introduce macros to allocate arraysPatrick Steinhardt1-2/+1
Similar to the preceding commit, let's carry over macros to allocate arrays with `REFTABLE_ALLOC_ARRAY()` and `REFTABLE_CALLOC_ARRAY()`. This requires us to change the signature of `reftable_calloc()`, which only takes a single argument right now and thus puts the burden on the caller to calculate the final array's size. This is a net improvement though as it means that we can now provide proper overflow checks when multiplying the array size with the member size. Convert callsites of `reftable_calloc()` to the new signature and start using the new macros where possible. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-20reftable: make reftable_record a tagged unionHan-Wen Nienhuys1-2/+2
This reduces the amount of glue code, because we don't need a void pointer or vtable within the structure. The only snag is that reftable_index_record contain a strbuf, so it cannot be zero-initialized. To address this, use reftable_new_record() to return fresh instance, given a record type. Since reftable_new_record() doesn't cause heap allocation anymore, it should be balanced with reftable_record_release() rather than reftable_record_destroy(). Thanks to Peff for the suggestion. Helped-by: Jeff King <peff@peff.net> Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08reftable: read reftable filesHan-Wen Nienhuys1-0/+194
This supports reading a single reftable file. The commit introduces an abstract iterator type, which captures the usecases both of reading individual refs, and iterating over a segment of the ref namespace. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>