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git/merge-ort.h

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merge-ort: barebones API of new merge strategy with empty implementation This is the beginning of a new merge strategy. While there are some API differences, and the implementation has some differences in behavior, it is essentially meant as an eventual drop-in replacement for merge-recursive.c. However, it is being built to exist side-by-side with merge-recursive so that we have plenty of time to find out how those differences pan out in the real world while people can still fall back to merge-recursive. (Also, I intend to avoid modifying merge-recursive during this process, to keep it stable.) The primary difference noticable here is that the updating of the working tree and index is not done simultaneously with the merge algorithm, but is a separate post-processing step. The new API is designed so that one can do repeated merges (e.g. during a rebase or cherry-pick) and only update the index and working tree one time at the end instead of updating it with every intermediate result. Also, one can perform a merge between two branches, neither of which match the index or the working tree, without clobbering the index or working tree. The next three commits will demonstrate various uses of this new API. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-27 02:08:07 +00:00
#ifndef MERGE_ORT_H
#define MERGE_ORT_H
#include "merge-recursive.h"
struct commit;
struct tree;
struct merge_result {
merge-ort: add an err() function similar to one from merge-recursive Various places in merge-recursive used an err() function when it hit some kind of unrecoverable error. That code was from the reusable bits of merge-recursive.c that we liked, such as merge_3way, writing object files to the object store, reading blobs from the object store, etc. So create a similar function to allow us to port that code over, and use it for when we detect problems returned from collect_merge_info()'s traverse_trees() call, which we will be adding next. While we are at it, also add more documentation for the "clean" field from struct merge_result, particularly since the name suggests a boolean but it is not quite one and this is our first non-boolean usage. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-12-13 08:04:12 +00:00
/*
* Whether the merge is clean; possible values:
* 1: clean
* 0: not clean (merge conflicts)
* <0: operation aborted prematurely. (object database
* unreadable, disk full, etc.) Worktree may be left in an
* inconsistent state if operation failed near the end.
*/
merge-ort: barebones API of new merge strategy with empty implementation This is the beginning of a new merge strategy. While there are some API differences, and the implementation has some differences in behavior, it is essentially meant as an eventual drop-in replacement for merge-recursive.c. However, it is being built to exist side-by-side with merge-recursive so that we have plenty of time to find out how those differences pan out in the real world while people can still fall back to merge-recursive. (Also, I intend to avoid modifying merge-recursive during this process, to keep it stable.) The primary difference noticable here is that the updating of the working tree and index is not done simultaneously with the merge algorithm, but is a separate post-processing step. The new API is designed so that one can do repeated merges (e.g. during a rebase or cherry-pick) and only update the index and working tree one time at the end instead of updating it with every intermediate result. Also, one can perform a merge between two branches, neither of which match the index or the working tree, without clobbering the index or working tree. The next three commits will demonstrate various uses of this new API. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-27 02:08:07 +00:00
int clean;
/*
* Result of merge. If !clean, represents what would go in worktree
* (thus possibly including files containing conflict markers).
*/
struct tree *tree;
/*
* Additional metadata used by merge_switch_to_result() or future calls
* to merge_incore_*(). Includes data needed to update the index (if
* !clean) and to print "CONFLICT" messages. Not for external use.
*/
void *priv;
merge-ort: avoid accidental API mis-use Previously, callers of the merge-ort API could have passed an uninitialized value for struct merge_result *result. However, we want to check result to see if it has cached renames from a previous merge that we can reuse; such values would be found behind result->priv. However, if result->priv is uninitialized, attempting to access behind it will give a segfault. So, we need result->priv to be NULL (which will be the case if the caller does a memset(&result, 0)), or be written by a previous call to the merge-ort machinery. Documenting this requirement may help, but despite being the person who introduced this requirement, I still missed it once and it did not fail in a very clear way and led to a long debugging session. Add a _properly_initialized field to merge_result; that value will be 0 if the caller zero'ed the merge_result, it will be set to a very specific value by a previous run by the merge-ort machinery, and if it's uninitialized it will most likely either be 0 or some value that does not match the specific one we'd expect allowing us to throw a much more meaningful error. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-20 06:09:37 +00:00
/* Also private */
unsigned _properly_initialized;
merge-ort: barebones API of new merge strategy with empty implementation This is the beginning of a new merge strategy. While there are some API differences, and the implementation has some differences in behavior, it is essentially meant as an eventual drop-in replacement for merge-recursive.c. However, it is being built to exist side-by-side with merge-recursive so that we have plenty of time to find out how those differences pan out in the real world while people can still fall back to merge-recursive. (Also, I intend to avoid modifying merge-recursive during this process, to keep it stable.) The primary difference noticable here is that the updating of the working tree and index is not done simultaneously with the merge algorithm, but is a separate post-processing step. The new API is designed so that one can do repeated merges (e.g. during a rebase or cherry-pick) and only update the index and working tree one time at the end instead of updating it with every intermediate result. Also, one can perform a merge between two branches, neither of which match the index or the working tree, without clobbering the index or working tree. The next three commits will demonstrate various uses of this new API. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-27 02:08:07 +00:00
};
/*
* rename-detecting three-way merge with recursive ancestor consolidation.
* working tree and index are untouched.
merge-ort: implement merge_incore_recursive() Implement merge_incore_recursive(), mostly through the use of a new helper function, merge_ort_internal(), which itself is based off merge_recursive_internal() from merge-recursive.c. This drops the number of failures in the testsuite when run under GIT_TEST_MERGE_ALGORITHM=ort from around 1500 to 647. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-12-16 22:28:02 +00:00
*
* merge_bases will be consumed (emptied) so make a copy if you need it.
*
* NOTE: empirically, the recursive algorithm will perform better if you
* pass the merge_bases in the order of oldest commit to the
* newest[1][2].
*
* [1] https://lore.kernel.org/git/nycvar.QRO.7.76.6.1907252055500.21907@tvgsbejvaqbjf.bet/
* [2] commit 8918b0c9c2 ("merge-recur: try to merge older merge bases
* first", 2006-08-09)
merge-ort: barebones API of new merge strategy with empty implementation This is the beginning of a new merge strategy. While there are some API differences, and the implementation has some differences in behavior, it is essentially meant as an eventual drop-in replacement for merge-recursive.c. However, it is being built to exist side-by-side with merge-recursive so that we have plenty of time to find out how those differences pan out in the real world while people can still fall back to merge-recursive. (Also, I intend to avoid modifying merge-recursive during this process, to keep it stable.) The primary difference noticable here is that the updating of the working tree and index is not done simultaneously with the merge algorithm, but is a separate post-processing step. The new API is designed so that one can do repeated merges (e.g. during a rebase or cherry-pick) and only update the index and working tree one time at the end instead of updating it with every intermediate result. Also, one can perform a merge between two branches, neither of which match the index or the working tree, without clobbering the index or working tree. The next three commits will demonstrate various uses of this new API. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-27 02:08:07 +00:00
*/
void merge_incore_recursive(struct merge_options *opt,
struct commit_list *merge_bases,
struct commit *side1,
struct commit *side2,
struct merge_result *result);
/*
* rename-detecting three-way merge, no recursion.
* working tree and index are untouched.
*/
void merge_incore_nonrecursive(struct merge_options *opt,
struct tree *merge_base,
struct tree *side1,
struct tree *side2,
struct merge_result *result);
/* Update the working tree and index from head to result after incore merge */
void merge_switch_to_result(struct merge_options *opt,
struct tree *head,
struct merge_result *result,
int update_worktree_and_index,
int display_update_msgs);
/* Do needed cleanup when not calling merge_switch_to_result() */
void merge_finalize(struct merge_options *opt,
struct merge_result *result);
#endif
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