diff options
| -rw-r--r-- | Documentation/config/reftable.txt | 8 | ||||
| -rw-r--r-- | refs/reftable-backend.c | 13 | ||||
| -rw-r--r-- | reftable/reftable-stack.h | 13 | ||||
| -rw-r--r-- | reftable/reftable-writer.h | 11 | ||||
| -rw-r--r-- | reftable/stack.c | 38 | ||||
| -rwxr-xr-x | t/t0610-reftable-basics.sh | 58 | ||||
| -rw-r--r-- | t/unit-tests/t-reftable-stack.c | 67 |
7 files changed, 189 insertions, 19 deletions
diff --git a/Documentation/config/reftable.txt b/Documentation/config/reftable.txt index 0515727977..57087803a5 100644 --- a/Documentation/config/reftable.txt +++ b/Documentation/config/reftable.txt @@ -46,3 +46,11 @@ reftable.geometricFactor:: By default, the geometric sequence uses a factor of 2, meaning that for any table, the next-biggest table must at least be twice as big. A maximum factor of 256 is supported. + +reftable.lockTimeout:: + Whenever the reftable backend appends a new table to the stack, it has + to lock the central "tables.list" file before updating it. This config + controls how long the process will wait to acquire the lock in case + another process has already acquired it. Value 0 means not to retry at + all; -1 means to try indefinitely. Default is 100 (i.e., retry for + 100ms). diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c index f5f957e6de..3c96fbf66f 100644 --- a/refs/reftable-backend.c +++ b/refs/reftable-backend.c @@ -260,6 +260,13 @@ static int reftable_be_config(const char *var, const char *value, if (factor > UINT8_MAX) die("reftable geometric factor cannot exceed %u", (unsigned)UINT8_MAX); opts->auto_compaction_factor = factor; + } else if (!strcmp(var, "reftable.locktimeout")) { + int64_t lock_timeout = git_config_int64(var, value, ctx->kvi); + if (lock_timeout > LONG_MAX) + die("reftable lock timeout cannot exceed %"PRIdMAX, (intmax_t)LONG_MAX); + if (lock_timeout < 0 && lock_timeout != -1) + die("reftable lock timeout does not support negative values other than -1"); + opts->lock_timeout_ms = lock_timeout; } return 0; @@ -286,6 +293,7 @@ static struct ref_store *reftable_be_init(struct repository *repo, refs->write_options.default_permissions = calc_shared_perm(0666 & ~mask); refs->write_options.disable_auto_compact = !git_env_bool("GIT_TEST_REFTABLE_AUTOCOMPACTION", 1); + refs->write_options.lock_timeout_ms = 100; git_config(reftable_be_config, &refs->write_options); @@ -893,7 +901,8 @@ static int prepare_transaction_update(struct write_transaction_table_arg **out, if (ret) return ret; - ret = reftable_stack_new_addition(&addition, stack); + ret = reftable_stack_new_addition(&addition, stack, + REFTABLE_STACK_NEW_ADDITION_RELOAD); if (ret) { if (ret == REFTABLE_LOCK_ERROR) strbuf_addstr(err, "cannot lock references"); @@ -2330,7 +2339,7 @@ static int reftable_be_reflog_expire(struct ref_store *ref_store, if (ret < 0) goto done; - ret = reftable_stack_new_addition(&add, stack); + ret = reftable_stack_new_addition(&add, stack, 0); if (ret < 0) goto done; diff --git a/reftable/reftable-stack.h b/reftable/reftable-stack.h index f4f8cabc7f..6370fe45dd 100644 --- a/reftable/reftable-stack.h +++ b/reftable/reftable-stack.h @@ -37,12 +37,21 @@ uint64_t reftable_stack_next_update_index(struct reftable_stack *st); /* holds a transaction to add tables at the top of a stack. */ struct reftable_addition; +enum { + /* + * Reload the stack when the stack is out-of-date after locking it. + */ + REFTABLE_STACK_NEW_ADDITION_RELOAD = (1 << 0), +}; + /* * returns a new transaction to add reftables to the given stack. As a side - * effect, the ref database is locked. + * effect, the ref database is locked. Accepts REFTABLE_STACK_NEW_ADDITION_* + * flags. */ int reftable_stack_new_addition(struct reftable_addition **dest, - struct reftable_stack *st); + struct reftable_stack *st, + unsigned int flags); /* Adds a reftable to transaction. */ int reftable_addition_add(struct reftable_addition *add, diff --git a/reftable/reftable-writer.h b/reftable/reftable-writer.h index 189b1f4144..f5e25cfda1 100644 --- a/reftable/reftable-writer.h +++ b/reftable/reftable-writer.h @@ -51,6 +51,17 @@ struct reftable_write_options { * tables to compact. Defaults to 2 if unset. */ uint8_t auto_compaction_factor; + + /* + * The number of milliseconds to wait when trying to lock "tables.list". + * Note that this does not apply to locking individual tables, as these + * should only ever be locked when already holding the "tables.list" + * lock. + * + * Passing 0 will fail immediately when the file is locked, passing a + * negative value will cause us to block indefinitely. + */ + long lock_timeout_ms; }; /* reftable_block_stats holds statistics for a single block type */ diff --git a/reftable/stack.c b/reftable/stack.c index ce0a35216b..84cf37a2ad 100644 --- a/reftable/stack.c +++ b/reftable/stack.c @@ -596,15 +596,18 @@ struct reftable_addition { #define REFTABLE_ADDITION_INIT {0} static int reftable_stack_init_addition(struct reftable_addition *add, - struct reftable_stack *st) + struct reftable_stack *st, + unsigned int flags) { struct strbuf lock_file_name = STRBUF_INIT; int err; add->stack = st; - err = hold_lock_file_for_update(&add->tables_list_lock, st->list_file, - LOCK_NO_DEREF); + err = hold_lock_file_for_update_timeout(&add->tables_list_lock, + st->list_file, + LOCK_NO_DEREF, + st->opts.lock_timeout_ms); if (err < 0) { if (errno == EEXIST) { err = REFTABLE_LOCK_ERROR; @@ -624,6 +627,11 @@ static int reftable_stack_init_addition(struct reftable_addition *add, err = stack_uptodate(st); if (err < 0) goto done; + if (err > 0 && flags & REFTABLE_STACK_NEW_ADDITION_RELOAD) { + err = reftable_stack_reload_maybe_reuse(add->stack, 1); + if (err) + goto done; + } if (err > 0) { err = REFTABLE_OUTDATED_ERROR; goto done; @@ -631,9 +639,8 @@ static int reftable_stack_init_addition(struct reftable_addition *add, add->next_update_index = reftable_stack_next_update_index(st); done: - if (err) { + if (err) reftable_addition_close(add); - } strbuf_release(&lock_file_name); return err; } @@ -737,13 +744,14 @@ done: } int reftable_stack_new_addition(struct reftable_addition **dest, - struct reftable_stack *st) + struct reftable_stack *st, + unsigned int flags) { int err = 0; struct reftable_addition empty = REFTABLE_ADDITION_INIT; REFTABLE_CALLOC_ARRAY(*dest, 1); **dest = empty; - err = reftable_stack_init_addition(*dest, st); + err = reftable_stack_init_addition(*dest, st, flags); if (err) { reftable_free(*dest); *dest = NULL; @@ -757,7 +765,7 @@ static int stack_try_add(struct reftable_stack *st, void *arg) { struct reftable_addition add = REFTABLE_ADDITION_INIT; - int err = reftable_stack_init_addition(&add, st); + int err = reftable_stack_init_addition(&add, st, 0); if (err < 0) goto done; @@ -1056,8 +1064,10 @@ static int stack_compact_range(struct reftable_stack *st, * Hold the lock so that we can read "tables.list" and lock all tables * which are part of the user-specified range. */ - err = hold_lock_file_for_update(&tables_list_lock, st->list_file, - LOCK_NO_DEREF); + err = hold_lock_file_for_update_timeout(&tables_list_lock, + st->list_file, + LOCK_NO_DEREF, + st->opts.lock_timeout_ms); if (err < 0) { if (errno == EEXIST) err = REFTABLE_LOCK_ERROR; @@ -1156,8 +1166,10 @@ static int stack_compact_range(struct reftable_stack *st, * "tables.list". We'll then replace the compacted range of tables with * the new table. */ - err = hold_lock_file_for_update(&tables_list_lock, st->list_file, - LOCK_NO_DEREF); + err = hold_lock_file_for_update_timeout(&tables_list_lock, + st->list_file, + LOCK_NO_DEREF, + st->opts.lock_timeout_ms); if (err < 0) { if (errno == EEXIST) err = REFTABLE_LOCK_ERROR; @@ -1602,7 +1614,7 @@ static int reftable_stack_clean_locked(struct reftable_stack *st) int reftable_stack_clean(struct reftable_stack *st) { struct reftable_addition *add = NULL; - int err = reftable_stack_new_addition(&add, st); + int err = reftable_stack_new_addition(&add, st, 0); if (err < 0) { goto done; } diff --git a/t/t0610-reftable-basics.sh b/t/t0610-reftable-basics.sh index 37510c2b2a..2d951c8ceb 100755 --- a/t/t0610-reftable-basics.sh +++ b/t/t0610-reftable-basics.sh @@ -423,6 +423,64 @@ test_expect_success 'ref transaction: fails gracefully when auto compaction fail ) ' +test_expect_success 'ref transaction: timeout acquiring tables.list lock' ' + test_when_finished "rm -rf repo" && + git init repo && + ( + cd repo && + test_commit initial && + >.git/reftable/tables.list.lock && + test_must_fail git update-ref refs/heads/branch HEAD 2>err && + test_grep "cannot lock references" err + ) +' + +test_expect_success 'ref transaction: retry acquiring tables.list lock' ' + test_when_finished "rm -rf repo" && + git init repo && + ( + cd repo && + test_commit initial && + LOCK=.git/reftable/tables.list.lock && + >$LOCK && + { + ( sleep 1 && rm -f $LOCK ) & + } && + git -c reftable.lockTimeout=5000 update-ref refs/heads/branch HEAD + ) +' + +test_expect_success 'ref transaction: many concurrent writers' ' + test_when_finished "rm -rf repo" && + git init repo && + ( + cd repo && + # Set a high timeout such that a busy CI machine will not abort + # early. 10 seconds should hopefully be ample of time to make + # this non-flaky. + git config set reftable.lockTimeout 10000 && + test_commit --no-tag initial && + + head=$(git rev-parse HEAD) && + for i in $(test_seq 100) + do + printf "%s commit\trefs/heads/branch-%s\n" "$head" "$i" || + return 1 + done >expect && + printf "%s commit\trefs/heads/main\n" "$head" >>expect && + + for i in $(test_seq 100) + do + { git update-ref refs/heads/branch-$i HEAD& } || + return 1 + done && + + wait && + git for-each-ref --sort=v:refname >actual && + test_cmp expect actual + ) +' + test_expect_success 'pack-refs: compacts tables' ' test_when_finished "rm -rf repo" && git init repo && diff --git a/t/unit-tests/t-reftable-stack.c b/t/unit-tests/t-reftable-stack.c index 65e513d5ec..31d563d992 100644 --- a/t/unit-tests/t-reftable-stack.c +++ b/t/unit-tests/t-reftable-stack.c @@ -267,7 +267,7 @@ static void t_reftable_stack_transaction_api(void) reftable_addition_destroy(add); - err = reftable_stack_new_addition(&add, st); + err = reftable_stack_new_addition(&add, st, 0); check(!err); err = reftable_addition_add(add, write_test_ref, &ref); @@ -288,6 +288,68 @@ static void t_reftable_stack_transaction_api(void) clear_dir(dir); } +static void t_reftable_stack_transaction_with_reload(void) +{ + char *dir = get_tmp_dir(__LINE__); + struct reftable_stack *st1 = NULL, *st2 = NULL; + int err; + struct reftable_addition *add = NULL; + struct reftable_ref_record refs[2] = { + { + .refname = (char *) "refs/heads/a", + .update_index = 1, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = { '1' }, + }, + { + .refname = (char *) "refs/heads/b", + .update_index = 2, + .value_type = REFTABLE_REF_VAL1, + .value.val1 = { '1' }, + }, + }; + struct reftable_ref_record ref = { 0 }; + + err = reftable_new_stack(&st1, dir, NULL); + check(!err); + err = reftable_new_stack(&st2, dir, NULL); + check(!err); + + err = reftable_stack_new_addition(&add, st1, 0); + check(!err); + err = reftable_addition_add(add, write_test_ref, &refs[0]); + check(!err); + err = reftable_addition_commit(add); + check(!err); + reftable_addition_destroy(add); + + /* + * The second stack is now outdated, which we should notice. We do not + * create the addition and lock the stack by default, but allow the + * reload to happen when REFTABLE_STACK_NEW_ADDITION_RELOAD is set. + */ + err = reftable_stack_new_addition(&add, st2, 0); + check_int(err, ==, REFTABLE_OUTDATED_ERROR); + err = reftable_stack_new_addition(&add, st2, REFTABLE_STACK_NEW_ADDITION_RELOAD); + check(!err); + err = reftable_addition_add(add, write_test_ref, &refs[1]); + check(!err); + err = reftable_addition_commit(add); + check(!err); + reftable_addition_destroy(add); + + for (size_t i = 0; i < ARRAY_SIZE(refs); i++) { + err = reftable_stack_read_ref(st2, refs[i].refname, &ref); + check(!err); + check(reftable_ref_record_equal(&refs[i], &ref, GIT_SHA1_RAWSZ)); + } + + reftable_ref_record_release(&ref); + reftable_stack_destroy(st1); + reftable_stack_destroy(st2); + clear_dir(dir); +} + static void t_reftable_stack_transaction_api_performs_auto_compaction(void) { char *dir = get_tmp_dir(__LINE__); @@ -318,7 +380,7 @@ static void t_reftable_stack_transaction_api_performs_auto_compaction(void) */ st->opts.disable_auto_compact = i != n; - err = reftable_stack_new_addition(&add, st); + err = reftable_stack_new_addition(&add, st, 0); check(!err); err = reftable_addition_add(add, write_test_ref, &ref); @@ -1313,6 +1375,7 @@ int cmd_main(int argc UNUSED, const char *argv[] UNUSED) TEST(t_reftable_stack_reload_with_missing_table(), "stack iteration with garbage tables"); TEST(t_reftable_stack_tombstone(), "'tombstone' refs in stack"); TEST(t_reftable_stack_transaction_api(), "update transaction to stack"); + TEST(t_reftable_stack_transaction_with_reload(), "transaction with reload"); TEST(t_reftable_stack_transaction_api_performs_auto_compaction(), "update transaction triggers auto-compaction"); TEST(t_reftable_stack_update_index_check(), "update transactions with equal update indices"); TEST(t_reftable_stack_uptodate(), "stack must be reloaded before ref update"); |