diff --git a/Documentation/config/hook.adoc b/Documentation/config/hook.adoc index b7847f9338..21800db648 100644 --- a/Documentation/config/hook.adoc +++ b/Documentation/config/hook.adoc @@ -23,6 +23,19 @@ hook..enabled:: in a system or global config file and needs to be disabled for a specific repository. See linkgit:git-hook[1]. +hook..parallel:: + Whether the hook `hook.` may run in parallel with other hooks + for the same event. Defaults to `false`. Set to `true` only when the + hook script is safe to run concurrently with other hooks for the same + event. If any hook for an event does not have this set to `true`, + all hooks for that event run sequentially regardless of `hook.jobs`. + Only configured (named) hooks need to declare this. Traditional hooks + found in the hooks directory do not need to, and run in parallel when + the effective job count is greater than 1. See linkgit:git-hook[1]. + hook.jobs:: Specifies how many hooks can be run simultaneously during parallelized hook execution. If unspecified, defaults to 1 (serial execution). ++ +This setting has no effect unless all configured hooks for the event have +`hook..parallel` set to `true`. diff --git a/hook.c b/hook.c index b8cce00e57..85c0de5e47 100644 --- a/hook.c +++ b/hook.c @@ -116,6 +116,7 @@ struct hook_config_cache_entry { char *command; enum config_scope scope; bool disabled; + bool parallel; }; /* @@ -123,12 +124,14 @@ struct hook_config_cache_entry { * commands: friendly-name to command map. * event_hooks: event-name to list of friendly-names map. * disabled_hooks: set of friendly-names with hook..enabled = false. + * parallel_hooks: friendly-name to parallel flag. * jobs: value of the global hook.jobs key. Defaults to 0 if unset (stored in r->hook_jobs). */ struct hook_all_config_cb { struct strmap commands; struct strmap event_hooks; struct string_list disabled_hooks; + struct strmap parallel_hooks; unsigned int jobs; }; @@ -219,6 +222,15 @@ static int hook_config_lookup_all(const char *key, const char *value, default: break; /* ignore unrecognised values */ } + } else if (!strcmp(subkey, "parallel")) { + int v = git_parse_maybe_bool(value); + if (v >= 0) + strmap_put(&data->parallel_hooks, hook_name, + (void *)(uintptr_t)v); + else + warning(_("hook.%s.parallel must be a boolean," + " ignoring: '%s'"), + hook_name, value); } free(hook_name); @@ -263,6 +275,7 @@ static void build_hook_config_map(struct repository *r, struct strmap *cache) strmap_init(&cb_data.commands); strmap_init(&cb_data.event_hooks); string_list_init_dup(&cb_data.disabled_hooks); + strmap_init(&cb_data.parallel_hooks); /* Parse all configs in one run, capturing hook.* including hook.jobs. */ repo_config(r, hook_config_lookup_all, &cb_data); @@ -282,6 +295,7 @@ static void build_hook_config_map(struct repository *r, struct strmap *cache) struct hook_config_cache_entry *entry; char *command; + bool is_par = !!strmap_get(&cb_data.parallel_hooks, hname); bool is_disabled = !!unsorted_string_list_lookup( &cb_data.disabled_hooks, hname); @@ -302,6 +316,7 @@ static void build_hook_config_map(struct repository *r, struct strmap *cache) entry->command = xstrdup_or_null(command); entry->scope = scope; entry->disabled = is_disabled; + entry->parallel = is_par; string_list_append(hooks, hname)->util = entry; } @@ -312,6 +327,7 @@ static void build_hook_config_map(struct repository *r, struct strmap *cache) r->hook_jobs = cb_data.jobs; strmap_clear(&cb_data.commands, 1); + strmap_clear(&cb_data.parallel_hooks, 0); /* values are uintptr_t, not heap ptrs */ string_list_clear(&cb_data.disabled_hooks, 0); strmap_for_each_entry(&cb_data.event_hooks, &iter, e) { string_list_clear(e->value, 0); @@ -389,6 +405,7 @@ static void list_hooks_add_configured(struct repository *r, entry->command ? xstrdup(entry->command) : NULL; hook->u.configured.scope = entry->scope; hook->u.configured.disabled = entry->disabled; + hook->parallel = entry->parallel; string_list_append(list, friendly_name)->util = hook; } @@ -538,21 +555,75 @@ static void run_hooks_opt_clear(struct run_hooks_opt *options) strvec_clear(&options->args); } +/* Determine how many jobs to use for hook execution. */ +static unsigned int get_hook_jobs(struct repository *r, + struct run_hooks_opt *options, + struct string_list *hook_list) +{ + /* + * Hooks needing separate output streams must run sequentially. + * Next commit will allow parallelizing these as well. + */ + if (!options->stdout_to_stderr) + return 1; + + /* + * An explicit job count overrides everything else: this covers both + * FORCE_SERIAL callers (for hooks that must never run in parallel) + * and the -j flag from the CLI. The CLI override is intentional: users + * may want to serialize hooks declared parallel or to parallelize more + * aggressively than the default. + */ + if (options->jobs) + return options->jobs; + + /* + * Use hook.jobs from the already-parsed config cache (in-repo), or + * fallback to a direct config lookup (out-of-repo). + * Default to 1 (serial execution) on failure. + */ + options->jobs = 1; + if (r) { + if (r->gitdir && r->hook_config_cache && r->hook_jobs) + options->jobs = r->hook_jobs; + else + repo_config_get_uint(r, "hook.jobs", &options->jobs); + } + + /* + * Cap to serial any configured hook not marked as parallel = true. + * This enforces the parallel = false default, even for "traditional" + * hooks from the hookdir which cannot be marked parallel = true. + */ + for (size_t i = 0; i < hook_list->nr; i++) { + struct hook *h = hook_list->items[i].util; + if (h->kind == HOOK_CONFIGURED && !h->parallel) { + options->jobs = 1; + break; + } + } + + return options->jobs; +} + int run_hooks_opt(struct repository *r, const char *hook_name, struct run_hooks_opt *options) { + struct string_list *hook_list = list_hooks(r, hook_name, options); struct hook_cb_data cb_data = { .rc = 0, .hook_name = hook_name, + .hook_command_list = hook_list, .options = options, }; int ret = 0; + unsigned int jobs = get_hook_jobs(r, options, hook_list); const struct run_process_parallel_opts opts = { .tr2_category = "hook", .tr2_label = hook_name, - .processes = options->jobs, - .ungroup = options->jobs == 1, + .processes = jobs, + .ungroup = jobs == 1, .get_next_task = pick_next_hook, .start_failure = notify_start_failure, @@ -568,9 +639,6 @@ int run_hooks_opt(struct repository *r, const char *hook_name, if (options->path_to_stdin && options->feed_pipe) BUG("options path_to_stdin and feed_pipe are mutually exclusive"); - if (!options->jobs) - BUG("run_hooks_opt must be called with options.jobs >= 1"); - /* * Ensure cb_data copy and free functions are either provided together, * or neither one is provided. @@ -581,7 +649,6 @@ int run_hooks_opt(struct repository *r, const char *hook_name, if (options->invoked_hook) *options->invoked_hook = 0; - cb_data.hook_command_list = list_hooks(r, hook_name, options); if (!cb_data.hook_command_list->nr) { if (options->error_if_missing) ret = error("cannot find a hook named %s", hook_name); diff --git a/hook.h b/hook.h index 5c5628dd1f..ba7056f872 100644 --- a/hook.h +++ b/hook.h @@ -35,6 +35,13 @@ struct hook { } configured; } u; + /** + * Whether this hook may run in parallel with other hooks for the same + * event. Only useful for configured (named) hooks. Traditional hooks + * always default to 0 (serial). Set via `hook..parallel = true`. + */ + bool parallel; + /** * Opaque data pointer used to keep internal state across callback calls. * @@ -72,6 +79,8 @@ struct run_hooks_opt { * * If > 1, output will be buffered and de-interleaved (ungroup=0). * If == 1, output will be real-time (ungroup=1). + * If == 0, the 'hook.jobs' config is used or, if the config is unset, + * defaults to 1 (serial execution). */ unsigned int jobs; @@ -152,7 +161,23 @@ struct run_hooks_opt { hook_data_free_fn feed_pipe_cb_data_free; }; +/** + * Default initializer for hooks. Parallelism is opt-in: .jobs = 0 defers to + * the 'hook.jobs' config, falling back to serial (1) if unset. + */ #define RUN_HOOKS_OPT_INIT { \ + .env = STRVEC_INIT, \ + .args = STRVEC_INIT, \ + .stdout_to_stderr = 1, \ + .jobs = 0, \ +} + +/** + * Initializer for hooks that must always run sequentially regardless of + * 'hook.jobs'. Use this when git knows the hook cannot safely be parallelized + * .jobs = 1 is non-overridable. + */ +#define RUN_HOOKS_OPT_INIT_FORCE_SERIAL { \ .env = STRVEC_INIT, \ .args = STRVEC_INIT, \ .stdout_to_stderr = 1, \ diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh index 33decc66c0..a3011a01ca 100755 --- a/t/t1800-hook.sh +++ b/t/t1800-hook.sh @@ -21,6 +21,57 @@ setup_hookdir () { test_when_finished rm -rf .git/hooks } +# write_sentinel_hook [sentinel] +# +# Writes a hook that marks itself as started, sleeps for a few seconds, then +# marks itself done. The sleep must be long enough that sentinel_detector can +# observe .started before .done appears when both hooks +# run concurrently in parallel mode. +write_sentinel_hook () { + sentinel="${2:-sentinel}" + write_script "$1" <<-EOF + touch ${sentinel}.started && + sleep 2 && + touch ${sentinel}.done + EOF +} + +# sentinel_detector +# +# Returns a shell command string suitable for use as hook..command. +# The detector must be registered after the sentinel: +# 1. In serial mode, the sentinel has completed (and .done exists) +# before the detector starts. +# 2. In parallel mode, both run concurrently so .done has not appeared +# yet and the detector just sees .started. +# +# At start, poll until .started exists to absorb startup jitter, then +# write to : +# 1. 'serial' if .done exists (sentinel finished before we started), +# 2. 'parallel' if only .started exists (sentinel still running), +# 3. 'timeout' if .started never appeared. +# +# The command ends with ':' so when git appends "$@" for hooks that receive +# positional arguments (e.g. pre-push), the result ': "$@"' is valid shell +# rather than a syntax error 'fi "$@"'. +sentinel_detector () { + cat <<-EOF + i=0 + while ! test -f ${1}.started && test \$i -lt 10; do + sleep 1 + i=\$((i+1)) + done + if test -f ${1}.done; then + echo serial >${2} + elif test -f ${1}.started; then + echo parallel >${2} + else + echo timeout >${2} + fi + : + EOF +} + test_expect_success 'git hook usage' ' test_expect_code 129 git hook && test_expect_code 129 git hook run && @@ -658,4 +709,95 @@ test_expect_success 'server push-to-checkout hook expects stdout redirected to s check_stdout_merged_to_stderr push-to-checkout ' +test_expect_success 'hook.jobs=1 config runs hooks in series' ' + test_when_finished "rm -f sentinel.started sentinel.done hook.order" && + + # Use two configured hooks so the execution order is deterministic: + # hook-1 (sentinel) is listed before hook-2 (detector), so hook-1 + # always runs first even in serial mode. + test_config hook.hook-1.event test-hook && + test_config hook.hook-1.command \ + "touch sentinel.started; sleep 2; touch sentinel.done" && + test_config hook.hook-2.event test-hook && + test_config hook.hook-2.command \ + "$(sentinel_detector sentinel hook.order)" && + + test_config hook.jobs 1 && + + git hook run --allow-unknown-hook-name test-hook >out 2>err && + echo serial >expect && + test_cmp expect hook.order +' + +test_expect_success 'hook.jobs=2 config runs hooks in parallel' ' + test_when_finished "rm -f sentinel.started sentinel.done hook.order" && + test_when_finished "rm -rf .git/hooks" && + + mkdir -p .git/hooks && + write_sentinel_hook .git/hooks/test-hook && + + test_config hook.hook-2.event test-hook && + test_config hook.hook-2.command \ + "$(sentinel_detector sentinel hook.order)" && + test_config hook.hook-2.parallel true && + + test_config hook.jobs 2 && + + git hook run --allow-unknown-hook-name test-hook >out 2>err && + echo parallel >expect && + test_cmp expect hook.order +' + +test_expect_success 'hook..parallel=true enables parallel execution' ' + test_when_finished "rm -f sentinel.started sentinel.done hook.order" && + test_config hook.hook-1.event test-hook && + test_config hook.hook-1.command \ + "touch sentinel.started; sleep 2; touch sentinel.done" && + test_config hook.hook-1.parallel true && + test_config hook.hook-2.event test-hook && + test_config hook.hook-2.command \ + "$(sentinel_detector sentinel hook.order)" && + test_config hook.hook-2.parallel true && + + test_config hook.jobs 2 && + + git hook run --allow-unknown-hook-name test-hook >out 2>err && + echo parallel >expect && + test_cmp expect hook.order +' + +test_expect_success 'hook..parallel=false (default) forces serial execution' ' + test_when_finished "rm -f sentinel.started sentinel.done hook.order" && + test_config hook.hook-1.event test-hook && + test_config hook.hook-1.command \ + "touch sentinel.started; sleep 2; touch sentinel.done" && + test_config hook.hook-2.event test-hook && + test_config hook.hook-2.command \ + "$(sentinel_detector sentinel hook.order)" && + + test_config hook.jobs 2 && + + git hook run --allow-unknown-hook-name test-hook >out 2>err && + echo serial >expect && + test_cmp expect hook.order +' + +test_expect_success 'one non-parallel hook forces the whole event to run serially' ' + test_when_finished "rm -f sentinel.started sentinel.done hook.order" && + test_config hook.hook-1.event test-hook && + test_config hook.hook-1.command \ + "touch sentinel.started; sleep 2; touch sentinel.done" && + test_config hook.hook-1.parallel true && + test_config hook.hook-2.event test-hook && + test_config hook.hook-2.command \ + "$(sentinel_detector sentinel hook.order)" && + # hook-2 has no parallel=true: should force serial for all + + test_config hook.jobs 2 && + + git hook run --allow-unknown-hook-name test-hook >out 2>err && + echo serial >expect && + test_cmp expect hook.order +' + test_done