Patrick Steinhardt
e77f412d84
The "rerere-gc" maintenance task is responsible for pruning rerere
entries older than a certain configurable cutoff point. Whether or not
the task gets run during auto-maintenance can be configured via
"maintenance.rerere-gc.auto":
- A negative value indicates that maintenance should always run.
- A zero value indicates that maintenance should never run.
- Otherwise, a positive value indicates that maintenance should always
run in case we have at least a single rerere entry.
While the first two conditions are sensible, the last one is less so as
it does not account for whether we would even prune old entries in the
first place. Instead, it effectively implies that we unconditionally
spawn "git rerere gc" when rerere is enabled. Chances are high though
that there is nothing to prune, as the default cutoff dates are 60 days
for resolved rerere entries and 15 days for unresolved ones.
Besides being a waste of compute, it also obstructs concurrent processes
that want to write new resolutions as garbage collection takes a central
lock file, as reported in [1]. That race is a longstanding one that
existed even before we introduced fine-grained maintenance tasks, and
the proper fix is to use a locking timeout in the writing processes. But
the race is made worse by us performing garbage collection a lot more
often.
Refine the heuristic to take into account whether any entries can be
pruned in the first place. This ensures that we'll only ever run this
task in situations where it will do anything, and should thus result in
a lot less frequent invocations of "git rerere gc".
Furthermore, tweak the meaning of "maintenance.rerere-gc.auto" so that
positive values allow the user to configure the number of prunable
entries that need to exist before we run it and set the default value to
512. This number is pulled out of thin air, but it ensures that we know
to batch-delete entries instead of pruning every single entry that is
older than the cutoff point.
Note that this now requires us to actually open the rerere-entry
directories and stat the individual files in there, which does add a bit
of overhead when one has lots of rerere entries. To counteract this
overhead, we thus use the same sampling heuristic as we do for loose
objects, where we only consider those entries that start with a "17".
[1]: <pull.2214.git.1788337897490.gitgitgadget@gmail.com>
Reported-by: Thomas Bachem <mail@thomasbachem.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
#ifndef RERERE_H
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#define RERERE_H
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#include "gettext.h"
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#include "string-list.h"
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struct pathspec;
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struct repository;
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#define RERERE_AUTOUPDATE 01
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#define RERERE_NOAUTOUPDATE 02
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#define RERERE_READONLY 04
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/*
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* Marks paths that have been hand-resolved and added to the
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* index. Set in the util field of such paths after calling
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* rerere_remaining.
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*/
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extern void *RERERE_RESOLVED;
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struct rerere_dir;
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struct rerere_id {
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struct rerere_dir *collection;
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int variant;
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};
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int setup_rerere(struct repository *,struct string_list *, int);
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int repo_rerere(struct repository *, int);
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/*
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* Given the conflict ID and the name of a "file" used for replaying
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* the recorded resolution (e.g. "preimage", "postimage"), return the
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* path to that filesystem entity. With "file" specified with NULL,
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* return the path to the directory that houses these files.
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*/
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const char *rerere_path(struct strbuf *buf, const struct rerere_id *,
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const char *file);
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int rerere_forget(struct repository *, struct pathspec *);
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int rerere_remaining(struct repository *, struct string_list *);
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void rerere_clear(struct repository *, struct string_list *);
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void rerere_gc(struct repository *, struct string_list *);
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/*
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* Check whether garbage collection for rerere entries is needed, which is
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* the case when there's at least `limit` stale entries that would be pruned.
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*/
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bool rerere_gc_needed(struct repository *r, size_t limit);
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#define OPT_RERERE_AUTOUPDATE(v) OPT_UYN(0, "rerere-autoupdate", (v), \
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N_("update the index with reused conflict resolution if possible"))
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#endif
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