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* Merge branch 'cw/log-updates-for-all-refs-really'Junio C Hamano2017-02-03
|\ | | | | | | | | | | | | | | | | | | | | | | | | The "core.logAllRefUpdates" that used to be boolean has been enhanced to take 'always' as well, to record ref updates to refs other than the ones that are expected to be updated (i.e. branches, remote-tracking branches and notes). * cw/log-updates-for-all-refs-really: doc: add note about ignoring '--no-create-reflog' update-ref: add test cases for bare repository refs: add option core.logAllRefUpdates = always config: add markup to core.logAllRefUpdates doc
| * refs: add option core.logAllRefUpdates = alwaysCornelius Weig2017-01-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When core.logallrefupdates is true, we only create a new reflog for refs that are under certain well-known hierarchies. The reason is that we know that some hierarchies (like refs/tags) are not meant to change, and that unknown hierarchies might not want reflogs at all (e.g., a hypothetical refs/foo might be meant to change often and drop old history immediately). However, sometimes it is useful to override this decision and simply log for all refs, because the safety and audit trail is more important than the performance implications of keeping the log around. This patch introduces a new "always" mode for the core.logallrefupdates option which will log updates to everything under refs/, regardless where in the hierarchy it is (we still will not log things like ORIG_HEAD and FETCH_HEAD, which are known to be transient). Based-on-patch-by: Jeff King <peff@peff.net> Signed-off-by: Cornelius Weig <cornelius.weig@tngtech.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | use oidcpy() for copying hashes between instances of struct object_idRené Scharfe2017-01-30
|/ | | | | | | Patch generated by Coccinelle and contrib/coccinelle/object_id.cocci. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Merge branch 'jk/ref-symlink-loop'Junio C Hamano2016-10-17
|\ | | | | | | | | | | | | | | | | A stray symbolic link in $GIT_DIR/refs/ directory could make name resolution loop forever, which has been corrected. * jk/ref-symlink-loop: files_read_raw_ref: prevent infinite retry loops in general files_read_raw_ref: avoid infinite loop on broken symlinks
| * files_read_raw_ref: prevent infinite retry loops in generalJeff King2016-10-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Limit the number of retries to 3. That should be adequate to prevent any races, while preventing the possibility of infinite loops if the logic fails to handle any other possible error modes correctly. After the fix in the previous commit, there's no known way to trigger an infinite loop, but I did manually verify that this fixes the test in that commit even when the code change is not applied. Signed-off-by: Jeff King <peff@peff.net> Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * files_read_raw_ref: avoid infinite loop on broken symlinksJeff King2016-10-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Our ref resolution first runs lstat() on any path we try to look up, because we want to treat symlinks specially (by resolving them manually and considering them symrefs). But if the results of `readlink` do _not_ look like a ref, we fall through to treating it like a normal file, and just read the contents of the linked path. Since fcb7c76 (resolve_ref_unsafe(): close race condition reading loose refs, 2013-06-19), that "normal file" code path will stat() the file and if we see ENOENT, will jump back to the lstat(), thinking we've seen inconsistent results between the two calls. But for a symbolic ref, this isn't a race: the lstat() found the symlink, and the stat() is looking at the path it points to. We end up in an infinite loop calling lstat() and stat(). We can fix this by avoiding the retry-on-inconsistent jump when we know that we found a symlink. While we're at it, let's add a comment explaining why the symlink case gets to this code in the first place; without that, it is not obvious that the correct solution isn't to avoid the stat() code path entirely. Signed-off-by: Jeff King <peff@peff.net> Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | use QSORTRené Scharfe2016-09-29
| | | | | | | | | | | | | | | | | | Apply the semantic patch contrib/coccinelle/qsort.cocci to the code base, replacing calls of qsort(3) with QSORT. The resulting code is shorter and supports empty arrays with NULL pointers. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'mh/ref-store'Junio C Hamano2016-09-19
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ref-store abstraction was introduced to the refs API so that we can plug in different backends to store references. * mh/ref-store: (38 commits) refs: implement iteration over only per-worktree refs refs: make lock generic refs: add method to rename refs refs: add methods to init refs db refs: make delete_refs() virtual refs: add method for initial ref transaction commit refs: add methods for reflog refs: add method iterator_begin files_ref_iterator_begin(): take a ref_store argument split_symref_update(): add a files_ref_store argument lock_ref_sha1_basic(): add a files_ref_store argument lock_ref_for_update(): add a files_ref_store argument commit_ref_update(): add a files_ref_store argument lock_raw_ref(): add a files_ref_store argument repack_without_refs(): add a files_ref_store argument refs: make peel_ref() virtual refs: make create_symref() virtual refs: make pack_refs() virtual refs: make verify_refname_available() virtual refs: make read_raw_ref() virtual ...
| * | refs: implement iteration over only per-worktree refsDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Alternate refs backends might still use files to store per-worktree refs. So provide a way to iterate over only the per-worktree references in a ref_store. The other backend can set up a files ref_store and iterate using the new DO_FOR_EACH_PER_WORKTREE_ONLY flag when iterating. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make lock genericDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of including a files-backend-specific struct ref_lock, change the generic ref_update struct to include a void pointer that backends can use for their own arbitrary data. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add method to rename refsDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This removes the last caller of function get_files_ref_store(), so remove it. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add methods to init refs dbDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Alternate refs backends might not need the refs/heads directory and so on, so we make ref db initialization part of the backend. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make delete_refs() virtualDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the file-based backend, delete_refs has some special optimization to deal with packed refs. In other backends, we might be able to make ref deletion faster by putting all deletions into a single transaction. So we need a special backend function for this. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add method for initial ref transaction commitDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | Signed-off-by: Ronnie Sahlberg <rsahlberg@google.com> Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add methods for reflogDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the file-based backend, the reflog piggybacks on the ref lock. Since other backends won't have the same sort of ref lock, ref backends must also handle reflogs. Signed-off-by: Ronnie Sahlberg <rsahlberg@google.com> Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add method iterator_beginMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | files_ref_iterator_begin(): take a ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | split_symref_update(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | lock_ref_sha1_basic(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | lock_ref_for_update(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | commit_ref_update(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | lock_raw_ref(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | repack_without_refs(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make peel_ref() virtualMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | For now it only supports the main reference store. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make create_symref() virtualMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make pack_refs() virtualMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make verify_refname_available() virtualMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: make read_raw_ref() virtualMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | Reference backends will be able to customize this function to implement reference reading. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | resolve_gitlink_ref(): implement using resolve_ref_recursively()Michael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | resolve_ref_recursively() can handle references in arbitrary files reference stores, so use it to resolve "gitlink" (i.e., submodule) references. Aside from removing redundant code, this allows submodule lookups to benefit from the much more robust code that we use for reading non-submodule references. And, since the code is now agnostic about reference backends, it will work for any future references backend (so move its definition to refs.c). Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | read_raw_ref(): take a (struct ref_store *) argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | And make the function work for submodules. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | resolve_gitlink_packed_ref(): remove functionMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | Now that resolve_packed_ref() can work with an arbitrary files_ref_store, there is no need to have a separate resolve_gitlink_packed_ref() function. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | resolve_packed_ref(): rename function from resolve_missing_loose_ref()Michael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: reorder definitionsMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | Move resolve_gitlink_ref() and related functions lower in the file to avoid the need for forward declarations in the next step. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add a transaction_commit() methodRonnie Sahlberg2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | Signed-off-by: Ronnie Sahlberg <sahlberg@google.com> Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | {lock,commit,rollback}_packed_refs(): add files_ref_store argumentsMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | These functions currently only work in the main repository, so add an assert_main_repository() check to each function. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | resolve_missing_loose_ref(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | get_packed_ref(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | add_packed_ref(): add a files_ref_store argumentMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: create a base class "ref_store" for files_ref_storeMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We want ref_stores to be polymorphic, so invent a base class of which files_ref_store is a derived class. For now there is exactly one ref_store for the main repository and one for any submodules whose references have been accessed. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: add a backend method structureRonnie Sahlberg2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a `struct ref_storage_be` to represent types of reference stores. In OO notation, this is the class, and will soon hold some class methods (e.g., a factory to create new ref_store instances) and will also serve as the vtable for ref_store instances of that type. As yet, the backends cannot do anything. Signed-off-by: Ronnie Sahlberg <sahlberg@google.com> Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | refs: rename struct ref_cache to files_ref_storeMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The greater goal of this patch series is to develop the concept of a reference store, which is a place that references, their values, and their reflogs are stored, and to virtualize the reference interface so that different types of ref_stores can be implemented. We will then, for example, use ref_store instances to access submodule references and worktree references. Currently, we keep a ref_cache for each submodule that has had its references iterated over. It is a far cry from a ref_store, but they are stored the way we will want to store ref_stores, and ref_stores will eventually have to hold the reference caches. So let's treat ref_caches as embryo ref_stores, and build them out from there. As the first step, simply rename `ref_cache` to `files_ref_store`, and rename some functions and attributes correspondingly. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | rename_ref_available(): add docstringDavid Turner2016-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | And improve the internal variable names. Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | resolve_gitlink_ref(): eliminate temporary variableMichael Haggerty2016-09-09
| | | | | | | | | | | | | | | Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | allow do_submodule_path to work even if submodule isn't checked outJacob Keller2016-08-31
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, do_submodule_path will attempt locating the .git directory by using read_gitfile on <path>/.git. If this fails it just assumes the <path>/.git is actually a git directory. This is good because it allows for handling submodules which were cloned in a regular manner first before being added to the superproject. Unfortunately this fails if the <path> is not actually checked out any longer, such as by removing the directory. Fix this by checking if the directory we found is actually a gitdir. In the case it is not, attempt to lookup the submodule configuration and find the name of where it is stored in the .git/modules/ directory of the superproject. If we can't locate the submodule configuration, this might occur because for example a submodule gitlink was added but the corresponding .gitmodules file was not properly updated. A die() here would not be pleasant to the users of submodule diff formats, so instead, modify do_submodule_path() to return an error code: - git_pathdup_submodule() returns NULL when we fail to find a path. - strbuf_git_path_submodule() propagates the error code to the caller. Modify the callers of these functions to check the error code and fail properly. This ensures we don't attempt to use a bad path that doesn't match the corresponding submodule. Because this change fixes add_submodule_odb() to work even if the submodule is not checked out, update the wording of the submodule log diff format to correctly display that the submodule is "not initialized" instead of "not checked out" Add tests to ensure this change works as expected. Signed-off-by: Jacob Keller <jacob.keller@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'mh/ref-iterators'Junio C Hamano2016-07-25
|\ \ | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The API to iterate over all the refs (i.e. for_each_ref(), etc.) has been revamped. * mh/ref-iterators: for_each_reflog(): reimplement using iterators dir_iterator: new API for iterating over a directory tree for_each_reflog(): don't abort for bad references do_for_each_ref(): reimplement using reference iteration refs: introduce an iterator interface ref_resolves_to_object(): new function entry_resolves_to_object(): rename function from ref_resolves_to_object() get_ref_cache(): only create an instance if there is a submodule remote rm: handle symbolic refs correctly delete_refs(): add a flags argument refs: use name "prefix" consistently do_for_each_ref(): move docstring to the header file refs: remove unnecessary "extern" keywords
| * for_each_reflog(): reimplement using iteratorsMichael Haggerty2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | | Allow references with reflogs to be iterated over using a ref_iterator. The latter is implemented as a files_reflog_iterator, which in turn uses dir_iterator to read the "logs" directory. Note that reflog iteration doesn't correctly handle per-worktree reflogs (either before or after this patch). Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * for_each_reflog(): don't abort for bad referencesMichael Haggerty2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If there is a file under "$GIT_DIR/logs" with no corresponding reference, the old code was emitting an error message, aborting the reflog iteration, and returning -1. But * None of the callers was checking the exit value * The callers all want to find all legitimate reflogs (sometimes for the purpose of determining object reachability!) and wouldn't benefit from a truncated iteration anyway. So instead, emit an error message and skip the "broken" reflog, but continue with the iteration. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * do_for_each_ref(): reimplement using reference iterationMichael Haggerty2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use the reference iterator interface to implement do_for_each_ref(). Delete a bunch of code supporting the old for_each_ref() implementation. And now that do_for_each_ref() is generic code (it is no longer tied to the files backend), move it to refs.c. The implementation is via a new function, do_for_each_ref_iterator(), which takes a reference iterator as argument and calls a callback function for each of the references in the iterator. This change requires the current_ref performance hack for peel_ref() to be implemented via ref_iterator_peel() rather than peel_entry() because we don't have a ref_entry handy (it is hidden under three layers: file_ref_iterator, merge_ref_iterator, and cache_ref_iterator). So: * do_for_each_ref_iterator() records the active iterator in current_ref_iter while it is running. * peel_ref() checks whether current_ref_iter is pointing at the requested reference. If so, it asks the iterator to peel the reference (which it can do efficiently via its "peel" virtual function). For extra safety, we do the optimization only if the refname *addresses* are the same, not only if the refname *strings* are the same, to forestall possible mixups between refnames that come from different ref_iterators. Please note that this optimization of peel_ref() is only available when iterating via do_for_each_ref_iterator() (including all of the for_each_ref() functions, which call it indirectly). It would be complicated to implement a similar optimization when iterating directly using a reference iterator, because multiple reference iterators can be in use at the same time, with interleaved calls to ref_iterator_advance(). (In fact we do exactly that in merge_ref_iterator.) But that is not necessary. peel_ref() is only called while iterating over references. Callers who iterate using the for_each_ref() functions benefit from the optimization described above. Callers who iterate using reference iterators directly have access to the ref_iterator, so they can call ref_iterator_peel() themselves to get an analogous optimization in a more straightforward manner. If we rewrite all callers to use the reference iteration API, then we can remove the current_ref_iter hack permanently. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * refs: introduce an iterator interfaceMichael Haggerty2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the API for iterating over references is via a family of for_each_ref()-type functions that invoke a callback function for each selected reference. All of these eventually call do_for_each_ref(), which knows how to do one thing: iterate in parallel through two ref_caches, one for loose and one for packed refs, giving loose references precedence over packed refs. This is rather complicated code, and is quite specialized to the files backend. It also requires callers to encapsulate their work into a callback function, which often means that they have to define and use a "cb_data" struct to manage their context. The current design is already bursting at the seams, and will become even more awkward in the upcoming world of multiple reference storage backends: * Per-worktree vs. shared references are currently handled via a kludge in git_path() rather than iterating over each part of the reference namespace separately and merging the results. This kludge will cease to work when we have multiple reference storage backends. * The current scheme is inflexible. What if we sometimes want to bypass the ref_cache, or use it only for packed or only for loose refs? What if we want to store symbolic refs in one type of storage backend and non-symbolic ones in another? In the future, each reference backend will need to define its own way of iterating over references. The crux of the problem with the current design is that it is impossible to compose for_each_ref()-style iterations, because the flow of control is owned by the for_each_ref() function. There is nothing that a caller can do but iterate through all references in a single burst, so there is no way for it to interleave references from multiple backends and present the result to the rest of the world as a single compound backend. This commit introduces a new iteration primitive for references: a ref_iterator. A ref_iterator is a polymorphic object that a reference storage backend can be asked to instantiate. There are three functions that can be applied to a ref_iterator: * ref_iterator_advance(): move to the next reference in the iteration * ref_iterator_abort(): end the iteration before it is exhausted * ref_iterator_peel(): peel the reference currently being looked at Iterating using a ref_iterator leaves the flow of control in the hands of the caller, which means that ref_iterators from multiple sources (e.g., loose and packed refs) can be composed and presented to the world as a single compound ref_iterator. It also means that the backend code for implementing reference iteration will sometimes be more complicated. For example, the cache_ref_iterator (which iterates over a ref_cache) can't use the C stack to recurse; instead, it must manage its own stack internally as explicit data structures. There is also a lot of boilerplate connected with object-oriented programming in C. Eventually, end-user callers will be able to be written in a more natural way—managing their own flow of control rather than having to work via callbacks. Since there will only be a few reference backends but there are many consumers of this API, this is a good tradeoff. More importantly, we gain composability, and especially the possibility of writing interchangeable parts that can work with any ref_iterator. For example, merge_ref_iterator implements a generic way of merging the contents of any two ref_iterators. It is used to merge loose + packed refs as part of the implementation of the files_ref_iterator. But it will also be possible to use it to merge other pairs of reference sources (e.g., per-worktree vs. shared refs). Another example is prefix_ref_iterator, which can be used to trim a prefix off the front of reference names before presenting them to the caller (e.g., "refs/heads/master" -> "master"). In this patch, we introduce the iterator abstraction and many utilities, and implement a reference iterator for the files ref storage backend. (I've written several other obvious utilities, for example a generic way to filter references being iterated over. These will probably be useful in the future. But they are not needed for this patch series, so I am not including them at this time.) In a moment we will rewrite do_for_each_ref() to work via reference iterators (allowing some special-purpose code to be discarded), and do something similar for reflogs. In future patch series, we will expose the ref_iterator abstraction in the public refs API so that callers can use it directly. Implementation note: I tried abstracting this a layer further to allow generic iterators (over arbitrary types of objects) and generic utilities like a generic merge_iterator. But the implementation in C was very cumbersome, involving (in my opinion) too much boilerplate and too much unsafe casting, some of which would have had to be done on the caller side. However, I did put a few iterator-related constants in a top-level header file, iterator.h, as they will be useful in a moment to implement iteration over directory trees and possibly other types of iterators in the future. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * ref_resolves_to_object(): new functionMichael Haggerty2016-06-20
| | | | | | | | | | | | | | | | | | Extract new function ref_resolves_to_object() from entry_resolves_to_object(). It can be used even if there is no ref_entry at hand. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
generated by cgit v1.2.1 (git 2.18.0) at 2024-07-03 12:52:45 +0000