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Mon, 28 Sep 2026 04:58:26 -0700 (PDT) Received: from [127.0.0.1] ([172.182.225.88]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-14a7c03ece2sm3015087c88.16.2026.09.28.04.58.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 04:58:26 -0700 (PDT) Message-Id: <27673137aae961105a3d3b6ea615879e0686cc65.1790596702.git.gitgitgadget@gmail.com> In-Reply-To: References: From: "Thomas Bachem via GitGitGadget" Date: Mon, 28 Sep 2026 11:58:21 +0000 Subject: [PATCH v5 2/3] rerere: add "gc --auto" that skips a held lock Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 To: git@vger.kernel.org Cc: Patrick Steinhardt , Phillip Wood , Junio C Hamano , Phillip Wood , Thomas Bachem , Thomas Bachem From: Thomas Bachem The previous commit made "git rerere gc" wait for MERGE_RR.lock like every other rerere command before it fails, as it always has. That suits a user who runs it by hand and wants to know when nothing was pruned. It does not suit the gc that auto maintenance starts after a commit: nobody is waiting for that run, and the next commit starts another one. So add "--auto", with which "git rerere gc" quietly does nothing when the lock is taken, and pass it from "git maintenance run --auto" and "git gc --auto", as they already do for "git pack-refs --auto". A run without it, from the command line or a maintenance schedule, keeps waiting and failing. Assisted-by: Claude Fable 5.1 Signed-off-by: Thomas Bachem --- Documentation/config/rerere.adoc | 3 ++- Documentation/git-rerere.adoc | 9 ++++++--- builtin/gc.c | 4 +++- builtin/rerere.c | 13 ++++++++++--- rerere.c | 22 +++++++++++++++++----- rerere.h | 4 +++- t/t4200-rerere.sh | 21 +++++++++++++++++++++ t/t7900-maintenance.sh | 25 ++++++++++++++++++++++++- 8 files changed, 86 insertions(+), 15 deletions(-) diff --git a/Documentation/config/rerere.adoc b/Documentation/config/rerere.adoc index 30e827f32b..a58c2ff684 100644 --- a/Documentation/config/rerere.adoc +++ b/Documentation/config/rerere.adoc @@ -17,4 +17,5 @@ rerere.lockTimeout:: `git rerere gc`. Value 0 means not to wait at all; -1 means to wait indefinitely. Default is 1000 (i.e., wait for 1 second). When the time is up, the command fails as it does - for any other lock it cannot take. + for any other lock it cannot take. `git rerere gc --auto` + does not wait and does nothing while the lock is held. diff --git a/Documentation/git-rerere.adoc b/Documentation/git-rerere.adoc index 4e6ab9a27c..da7a1d093e 100644 --- a/Documentation/git-rerere.adoc +++ b/Documentation/git-rerere.adoc @@ -8,7 +8,7 @@ git-rerere - Reuse recorded resolution of conflicted merges SYNOPSIS -------- [verse] -'git rerere' [clear | forget ... | diff | status | remaining | gc] +'git rerere' [clear | forget ... | diff | status | remaining | gc [--auto]] DESCRIPTION ----------- @@ -63,14 +63,17 @@ Print paths with conflicts that have not been autoresolved by rerere. This includes paths whose resolutions cannot be tracked by rerere, such as conflicting submodules. -'gc':: +'gc' [--auto]:: Prune records of conflicted merges that occurred a long time ago. By default, unresolved conflicts older than 15 days and resolved conflicts older than 60 days are pruned. These defaults are controlled via the `gc.rerereUnresolved` and `gc.rerereResolved` configuration -variables respectively. +variables respectively. With `--auto`, which `git maintenance run +--auto` and `git gc --auto` pass, `gc` does nothing while another +process holds the rerere lock. Without it, `gc` waits for the lock +as long as `rerere.lockTimeout` allows and then fails. DISCUSSION diff --git a/builtin/gc.c b/builtin/gc.c index 57a3520263..5c33082b5b 100644 --- a/builtin/gc.c +++ b/builtin/gc.c @@ -385,12 +385,14 @@ out: return should_prune; } -static int maintenance_task_rerere_gc(struct maintenance_run_opts *opts UNUSED, +static int maintenance_task_rerere_gc(struct maintenance_run_opts *opts, struct gc_config *cfg UNUSED) { struct child_process rerere_cmd = CHILD_PROCESS_INIT; rerere_cmd.git_cmd = 1; strvec_pushl(&rerere_cmd.args, "rerere", "gc", NULL); + if (opts->auto_flag) + strvec_push(&rerere_cmd.args, "--auto"); return run_command(&rerere_cmd); } diff --git a/builtin/rerere.c b/builtin/rerere.c index a056cb791b..2a8871df41 100644 --- a/builtin/rerere.c +++ b/builtin/rerere.c @@ -12,7 +12,8 @@ #include "pathspec.h" static const char * const rerere_usage[] = { - N_("git rerere [clear | forget ... | diff | status | remaining | gc]"), + N_("git rerere [clear | forget ... | diff | status | " + "remaining | gc [--auto]]"), NULL, }; @@ -56,16 +57,21 @@ int cmd_rerere(int argc, struct repository *repo UNUSED) { struct string_list merge_rr = STRING_LIST_INIT_DUP; - int autoupdate = -1, flags = 0; + int autoupdate = -1, auto_flag = 0, flags = 0; struct option options[] = { OPT_SET_INT(0, "rerere-autoupdate", &autoupdate, N_("register clean resolutions in index"), 1), + OPT_BOOL(0, "auto", &auto_flag, + N_("skip gc while another process holds the lock")), OPT_END(), }; argc = parse_options(argc, argv, prefix, options, rerere_usage, 0); + if (auto_flag && (argc < 1 || strcmp(argv[0], "gc"))) + die(_("the option '%s' requires '%s'"), "--auto", "gc"); + repo_config(the_repository, git_xmerge_config, NULL); if (autoupdate == 1) @@ -94,7 +100,8 @@ int cmd_rerere(int argc, if (!strcmp(argv[0], "clear")) { rerere_clear(the_repository, &merge_rr); } else if (!strcmp(argv[0], "gc")) - rerere_gc(the_repository, &merge_rr); + rerere_gc(the_repository, &merge_rr, + auto_flag ? RERERE_NOWAIT : 0); else if (!strcmp(argv[0], "status")) { if (setup_rerere(the_repository, &merge_rr, flags | RERERE_READONLY) < 0) diff --git a/rerere.c b/rerere.c index 64fac07c71..43c8eb04db 100644 --- a/rerere.c +++ b/rerere.c @@ -887,18 +887,30 @@ int setup_rerere(struct repository *r, struct string_list *merge_rr, int flags) if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE)) rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE); + if ((flags & RERERE_READONLY) && (flags & RERERE_NOWAIT)) + BUG("RERERE_NOWAIT does not apply with RERERE_READONLY"); if (flags & RERERE_READONLY) { fd = 0; } else { + int lock_flags = LOCK_DIE_ON_ERROR; + int timeout_ms = rerere_lock_timeout_ms; + /* * Another process may hold the lock for a while, e.g. * "git rerere gc" while it prunes rr-cache, so wait for - * it instead of dying right away. + * it instead of dying right away. The gc of an automatic + * maintenance run does not wait, since skipping one of + * its runs costs nothing. */ + if (flags & RERERE_NOWAIT) { + lock_flags = 0; + timeout_ms = 0; + } fd = repo_hold_lock_file_for_update_timeout(r, &write_lock, git_path_merge_rr(r), - LOCK_DIE_ON_ERROR, - rerere_lock_timeout_ms); + lock_flags, timeout_ms); + if (fd < 0) + return -1; } read_rr(r, merge_rr); return fd; @@ -1284,7 +1296,7 @@ out: return needed; } -void rerere_gc(struct repository *r, struct string_list *rr) +void rerere_gc(struct repository *r, struct string_list *rr, int flags) { struct string_list to_remove = STRING_LIST_INIT_DUP; DIR *dir; @@ -1294,7 +1306,7 @@ void rerere_gc(struct repository *r, struct string_list *rr) timestamp_t cutoff_resolve; struct strbuf buf = STRBUF_INIT; - if (setup_rerere(r, rr, 0) < 0) + if (setup_rerere(r, rr, flags) < 0) return; rerere_gc_cutoffs(r, &cutoff_resolve, &cutoff_noresolve); diff --git a/rerere.h b/rerere.h index feeb0e2c9f..d54c53d0d4 100644 --- a/rerere.h +++ b/rerere.h @@ -10,6 +10,8 @@ struct repository; #define RERERE_AUTOUPDATE 01 #define RERERE_NOAUTOUPDATE 02 #define RERERE_READONLY 04 +/* Take MERGE_RR.lock only if it is free, and return quietly otherwise */ +#define RERERE_NOWAIT 010 /* * Marks paths that have been hand-resolved and added to the @@ -37,7 +39,7 @@ const char *rerere_path(struct strbuf *buf, const struct rerere_id *, int rerere_forget(struct repository *, struct pathspec *); int rerere_remaining(struct repository *, struct string_list *); void rerere_clear(struct repository *, struct string_list *); -void rerere_gc(struct repository *, struct string_list *); +void rerere_gc(struct repository *, struct string_list *, int); /* * Check whether garbage collection for rerere entries is needed, which is diff --git a/t/t4200-rerere.sh b/t/t4200-rerere.sh index 7bd92235dc..9435b0ed58 100755 --- a/t/t4200-rerere.sh +++ b/t/t4200-rerere.sh @@ -242,6 +242,27 @@ test_expect_success 'old records rest in peace' ' test_path_is_missing $rr2/preimage ' +test_expect_success 'gc --auto does nothing while MERGE_RR is locked' ' + mkdir -p $rr2 && + echo Hello >$rr2/preimage && + test-tool chmtime =$just_over_15_days_ago $rr2/preimage && + + test_when_finished "rm -f .git/MERGE_RR.lock" && + >.git/MERGE_RR.lock && + git rerere gc --auto 2>err && + test_must_be_empty err && + test_path_is_file $rr2/preimage && + + rm .git/MERGE_RR.lock && + git rerere gc --auto && + test_path_is_missing $rr2/preimage +' + +test_expect_success '--auto is only accepted by gc' ' + test_must_fail git rerere --auto clear 2>err && + test_grep "option .--auto. requires .gc." err +' + test_expect_success 'a held lock is waited out within rerere.lockTimeout' ' git reset --hard && rm -rf $rr && diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh index 4f65fa9439..8842340236 100755 --- a/t/t7900-maintenance.sh +++ b/t/t7900-maintenance.sh @@ -1007,9 +1007,17 @@ test_expect_rerere_gc () { shift fi + # an automatic run passes --auto on to "git rerere gc" + auto= + case " $* " in + *" --auto "*) + auto=--auto + ;; + esac + rm -f "rerere-gc.txt" && GIT_TRACE2_EVENT="$(pwd)/rerere-gc.txt" "$@" && - test_subcommand $negate git rerere gc .git/MERGE_RR.lock && + test_expect_rerere_gc git -c maintenance.rerere-gc.auto=-1 maintenance run --auto --task=rerere-gc +' + +test_expect_success 'rerere-gc task without --auto fails while MERGE_RR is locked' ' + test_when_finished "rm -rf .git/rr-cache .git/MERGE_RR.lock" && + mkdir .git/rr-cache && + >.git/MERGE_RR.lock && + test_must_fail git -c rerere.lockTimeout=0 maintenance run --task=rerere-gc 2>err && + test_grep "Unable to create" err +' + test_expect_success '--auto and --schedule incompatible' ' test_must_fail git maintenance run --auto --schedule=daily 2>err && test_grep "cannot be used together" err -- gitgitgadget