git/refs.c, branch v2.32.2

Merge branch 'bc/hash-transition-interop-part-1'

2021-05-10T07:59:46Z

SHA-256 transition. * bc/hash-transition-interop-part-1: hex: print objects using the hash algorithm member hex: default to the_hash_algo on zero algorithm value builtin/pack-objects: avoid using struct object_id for pack hash commit-graph: don't store file hashes as struct object_id builtin/show-index: set the algorithm for object IDs hash: provide per-algorithm null OIDs hash: set, copy, and use algo field in struct object_id builtin/pack-redundant: avoid casting buffers to struct object_id Use the final_oid_fn to finalize hashing of object IDs hash: add a function to finalize object IDs http-push: set algorithm when reading object ID Always use oidread to read into struct object_id hash: add an algo member to struct object_id

hash: provide per-algorithm null OIDs

2021-04-27T07:31:39Z

Up until recently, object IDs did not have an algorithm member, only a hash. Consequently, it was possible to share one null (all-zeros) object ID among all hash algorithms. Now that we're going to be handling objects from multiple hash algorithms, it's important to make sure that all object IDs have a correct algorithm field. Introduce a per-algorithm null OID, and add it to struct hash_algo. Introduce a wrapper function as well, and use it everywhere we used to use the null_oid constant. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano

lookup_unknown_object(): take a repository argument

2021-04-13T20:18:46Z

All of the other lookup_foo() functions take a repository argument, but lookup_unknown_object() was never converted, and it uses the_repository internally. Let's fix that. We could leave a wrapper that uses the_repository, but there aren't that many calls, so we'll just convert them all. I looked briefly at each site to see if we had a repository struct (besides the_repository) we could pass, but none of them do (so this conversion to pass the_repository is a pure noop in each case, though it does take us one step closer to eventually getting rid of the_repository). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

use CALLOC_ARRAY

2021-03-14T00:00:09Z

Add and apply a semantic patch for converting code that open-codes CALLOC_ARRAY to use it instead. It shortens the code and infers the element size automatically. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

Merge branch 'tb/ls-refs-optim'

2021-02-06T00:40:45Z

The ls-refs protocol operation has been optimized to narrow the sub-hierarchy of refs/ it walks to produce response. * tb/ls-refs-optim: ls-refs.c: traverse prefixes of disjoint "ref-prefix" sets ls-refs.c: initialize 'prefixes' before using it refs: expose 'for_each_fullref_in_prefixes'

Merge branch 'jk/peel-iterated-oid'

2021-02-03T23:04:49Z

The peel_ref() API has been replaced with peel_iterated_oid(). * jk/peel-iterated-oid: refs: switch peel_ref() to peel_iterated_oid()

refs: expose 'for_each_fullref_in_prefixes'

2021-01-23T02:57:27Z

This function was used in the ref-filter.c code to find the longest common prefix of among a set of refspecs, and then to iterate all of the references that descend from that prefix. A future patch will want to use that same code from ls-refs.c, so prepare by exposing and moving it to refs.c. Since there is nothing specific to the ref-filter code here (other than that it was previously the only caller of this function), this really belongs in the more generic refs.h header. The code moved in this patch is identical before and after, with the one exception of renaming some arguments to be consistent with other functions exposed in refs.h. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

refs: switch peel_ref() to peel_iterated_oid()

2021-01-21T23:51:31Z

The peel_ref() interface is confusing and error-prone: - it's typically used by ref iteration callbacks that have both a refname and oid. But since they pass only the refname, we may load the ref value from the filesystem again. This is inefficient, but also means we are open to a race if somebody simultaneously updates the ref. E.g., this: int some_ref_cb(const char *refname, const struct object_id *oid, ...) { if (!peel_ref(refname, &peeled)) printf("%s peels to %s", oid_to_hex(oid), oid_to_hex(&peeled); } could print nonsense. It is correct to say "refname peels to..." (you may see the "before" value or the "after" value, either of which is consistent), but mentioning both oids may be mixing before/after values. Worse, whether this is possible depends on whether the optimization to read from the current iterator value kicks in. So it is actually not possible with: for_each_ref(some_ref_cb); but it _is_ possible with: head_ref(some_ref_cb); which does not use the iterator mechanism (though in practice, HEAD should never peel to anything, so this may not be triggerable). - it must take a fully-qualified refname for the read_ref_full() code path to work. Yet we routinely pass it partial refnames from callbacks to for_each_tag_ref(), etc. This happens to work when iterating because there we do not call read_ref_full() at all, and only use the passed refname to check if it is the same as the iterator. But the requirements for the function parameters are quite unclear. Instead of taking a refname, let's instead take an oid. That fixes both problems. It's a little funny for a "ref" function not to involve refs at all. The key thing is that it's optimizing under the hood based on having access to the ref iterator. So let's change the name to make it clear why you'd want this function versus just peel_object(). There are two other directions I considered but rejected: - we could pass the peel information into the each_ref_fn callback. However, we don't know if the caller actually wants it or not. For packed-refs, providing it is essentially free. But for loose refs, we actually have to peel the object, which would be wasteful in most cases. We could likewise pass in a flag to the callback indicating whether the peeled information is known, but that complicates those callbacks, as they then have to decide whether to manually peel themselves. Plus it requires changing the interface of every callback, whether they care about peeling or not, and there are many of them. - we could make a function to return the peeled value of the current iterated ref (computing it if necessary), and BUG() otherwise. I.e.: int peel_current_iterated_ref(struct object_id *out); Each of the current callers is an each_ref_fn callback, so they'd mostly be happy. But: - we use those callbacks with functions like head_ref(), which do not use the iteration code. So we'd need to handle the fallback case there, anyway. - it's possible that a caller would want to call into generic code that sometimes is used during iteration and sometimes not. This encapsulates the logic to do the fast thing when possible, and fallback when necessary. The implementation is mostly obvious, but I want to call out a few things in the patch: - the test-tool coverage for peel_ref() is now meaningless, as it all collapses to a single peel_object() call (arguably they were pretty uninteresting before; the tricky part of that function is the fast-path we see during iteration, but these calls didn't trigger that). I've just dropped it entirely, though note that some other tests relied on the tags we created; I've moved that creation to the tests where it matters. - we no longer need to take a ref_store parameter, since we'd never look up a ref now. We do still rely on a global "current iterator" variable which _could_ be kept per-ref-store. But in practice this is only useful if there are multiple recursive iterations, at which point the more appropriate solution is probably a stack of iterators. No caller used the actual ref-store parameter anyway (they all call the wrapper that passes the_repository). - the original only kicked in the optimization when the "refname" pointer matched (i.e., not string comparison). We do likewise with the "oid" parameter here, but fall back to doing an actual oideq() call. This in theory lets us kick in the optimization more often, though in practice no current caller cares. It should never be wrong, though (peeling is a property of an object, so two refs pointing to the same object would peel identically). - the original took care not to touch the peeled out-parameter unless we found something to put in it. But no caller cares about this, and anyway, it is enforced by peel_object() itself (and even in the optimized iterator case, that's where we eventually end up). We can shorten the code and avoid an extra copy by just passing the out-parameter through the stack. Signed-off-by: Jeff King Reviewed-by: Taylor Blau Signed-off-by: Junio C Hamano

refs: allow @{n} to work with n-sized reflog

2021-01-11T22:13:50Z

This sequence works $ git checkout -b newbranch $ git commit --allow-empty -m one $ git show -s newbranch@{1} and shows the state that was immediately after the newbranch was created. But then if you do $ git reflog expire --expire=now refs/heads/newbranch $ git commit --allow=empty -m two $ git show -s newbranch@{1} you'd be scolded with fatal: log for 'newbranch' only has 1 entries While it is true that it has only 1 entry, we have enough information in that single entry that records the transition between the state in which the tip of the branch was pointing at commit 'one' to the new commit 'two' built on it, so we should be able to answer "what object newbranch was pointing at?". But we refuse to do so. Make @{0} the special case where we use the new side to look up that entry. Otherwise, look up @{n} using the old side of the (n-1)th entry of the reflog. Suggested-by: Junio C Hamano Signed-off-by: Denton Liu Signed-off-by: Junio C Hamano

refs: factor out set_read_ref_cutoffs()

2021-01-10T20:24:00Z

This block of code is duplicated twice. In a future commit, it will be duplicated for a third time. Factor out the common functionality into set_read_ref_cutoffs(). In the case of read_ref_at_ent(), we are incrementing `cb->reccnt` at the beginning of the function. Move these to right before the return so that the `cb->reccnt - 1` is changed to `cb->reccnt` and it can be cleanly factored out into set_read_ref_cutoffs(). The duplication of the increment statements will be removed in a future patch. Signed-off-by: Denton Liu Signed-off-by: Junio C Hamano