diff options
| -rw-r--r-- | builtin/fsmonitor--daemon.c | 237 | ||||
| -rw-r--r-- | fsmonitor--daemon.h | 5 |
2 files changed, 241 insertions, 1 deletions
diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c index ab9cc09f7c..46be55a461 100644 --- a/builtin/fsmonitor--daemon.c +++ b/builtin/fsmonitor--daemon.c @@ -107,6 +107,162 @@ static int do_as_client__status(void) } } +enum fsmonitor_cookie_item_result { + FCIR_ERROR = -1, /* could not create cookie file ? */ + FCIR_INIT, + FCIR_SEEN, + FCIR_ABORT, +}; + +struct fsmonitor_cookie_item { + struct hashmap_entry entry; + char *name; + enum fsmonitor_cookie_item_result result; +}; + +static int cookies_cmp(const void *data, const struct hashmap_entry *he1, + const struct hashmap_entry *he2, const void *keydata) +{ + const struct fsmonitor_cookie_item *a = + container_of(he1, const struct fsmonitor_cookie_item, entry); + const struct fsmonitor_cookie_item *b = + container_of(he2, const struct fsmonitor_cookie_item, entry); + + return strcmp(a->name, keydata ? keydata : b->name); +} + +static enum fsmonitor_cookie_item_result with_lock__wait_for_cookie( + struct fsmonitor_daemon_state *state) +{ + /* assert current thread holding state->main_lock */ + + int fd; + struct fsmonitor_cookie_item *cookie; + struct strbuf cookie_pathname = STRBUF_INIT; + struct strbuf cookie_filename = STRBUF_INIT; + enum fsmonitor_cookie_item_result result; + int my_cookie_seq; + + CALLOC_ARRAY(cookie, 1); + + my_cookie_seq = state->cookie_seq++; + + strbuf_addf(&cookie_filename, "%i-%i", getpid(), my_cookie_seq); + + strbuf_addbuf(&cookie_pathname, &state->path_cookie_prefix); + strbuf_addbuf(&cookie_pathname, &cookie_filename); + + cookie->name = strbuf_detach(&cookie_filename, NULL); + cookie->result = FCIR_INIT; + hashmap_entry_init(&cookie->entry, strhash(cookie->name)); + + hashmap_add(&state->cookies, &cookie->entry); + + trace_printf_key(&trace_fsmonitor, "cookie-wait: '%s' '%s'", + cookie->name, cookie_pathname.buf); + + /* + * Create the cookie file on disk and then wait for a notification + * that the listener thread has seen it. + */ + fd = open(cookie_pathname.buf, O_WRONLY | O_CREAT | O_EXCL, 0600); + if (fd < 0) { + error_errno(_("could not create fsmonitor cookie '%s'"), + cookie->name); + + cookie->result = FCIR_ERROR; + goto done; + } + + /* + * Technically, close() and unlink() can fail, but we don't + * care here. We only created the file to trigger a watch + * event from the FS to know that when we're up to date. + */ + close(fd); + unlink(cookie_pathname.buf); + + /* + * Technically, this is an infinite wait (well, unless another + * thread sends us an abort). I'd like to change this to + * use `pthread_cond_timedwait()` and return an error/timeout + * and let the caller do the trivial response thing, but we + * don't have that routine in our thread-utils. + * + * After extensive beta testing I'm not really worried about + * this. Also note that the above open() and unlink() calls + * will cause at least two FS events on that path, so the odds + * of getting stuck are pretty slim. + */ + while (cookie->result == FCIR_INIT) + pthread_cond_wait(&state->cookies_cond, + &state->main_lock); + +done: + hashmap_remove(&state->cookies, &cookie->entry, NULL); + + result = cookie->result; + + free(cookie->name); + free(cookie); + strbuf_release(&cookie_pathname); + + return result; +} + +/* + * Mark these cookies as _SEEN and wake up the corresponding client threads. + */ +static void with_lock__mark_cookies_seen(struct fsmonitor_daemon_state *state, + const struct string_list *cookie_names) +{ + /* assert current thread holding state->main_lock */ + + int k; + int nr_seen = 0; + + for (k = 0; k < cookie_names->nr; k++) { + struct fsmonitor_cookie_item key; + struct fsmonitor_cookie_item *cookie; + + key.name = cookie_names->items[k].string; + hashmap_entry_init(&key.entry, strhash(key.name)); + + cookie = hashmap_get_entry(&state->cookies, &key, entry, NULL); + if (cookie) { + trace_printf_key(&trace_fsmonitor, "cookie-seen: '%s'", + cookie->name); + cookie->result = FCIR_SEEN; + nr_seen++; + } + } + + if (nr_seen) + pthread_cond_broadcast(&state->cookies_cond); +} + +/* + * Set _ABORT on all pending cookies and wake up all client threads. + */ +static void with_lock__abort_all_cookies(struct fsmonitor_daemon_state *state) +{ + /* assert current thread holding state->main_lock */ + + struct hashmap_iter iter; + struct fsmonitor_cookie_item *cookie; + int nr_aborted = 0; + + hashmap_for_each_entry(&state->cookies, &iter, cookie, entry) { + trace_printf_key(&trace_fsmonitor, "cookie-abort: '%s'", + cookie->name); + cookie->result = FCIR_ABORT; + nr_aborted++; + } + + if (nr_aborted) + pthread_cond_broadcast(&state->cookies_cond); +} + /* * Requests to and from a FSMonitor Protocol V2 provider use an opaque * "token" as a virtual timestamp. Clients can request a summary of all @@ -404,6 +560,9 @@ static void fsmonitor_free_token_data(struct fsmonitor_token_data *token) * We should create a new token and start fresh (as if we just * booted up). * + * [2] Some of those lost events may have been for cookie files. We + * should assume the worst and abort them rather letting them starve. + * * If there are no concurrent threads reading the current token data * series, we can free it now. Otherwise, let the last reader free * it. @@ -425,6 +584,8 @@ static void with_lock__do_force_resync(struct fsmonitor_daemon_state *state) state->current_token_data = new_one; fsmonitor_free_token_data(free_me); + + with_lock__abort_all_cookies(state); } void fsmonitor_force_resync(struct fsmonitor_daemon_state *state) @@ -500,6 +661,8 @@ static int do_handle_client(struct fsmonitor_daemon_state *state, int hash_ret; int do_trivial = 0; int do_flush = 0; + int do_cookie = 0; + enum fsmonitor_cookie_item_result cookie_result; /* * We expect `command` to be of the form: @@ -560,6 +723,7 @@ static int do_handle_client(struct fsmonitor_daemon_state *state, * We have a V2 valid token: * "builtin:<token_id>:<seq_nr>" */ + do_cookie = 1; } } @@ -568,6 +732,30 @@ static int do_handle_client(struct fsmonitor_daemon_state *state, if (!state->current_token_data) BUG("fsmonitor state does not have a current token"); + /* + * Write a cookie file inside the directory being watched in + * an effort to flush out existing filesystem events that we + * actually care about. Suspend this client thread until we + * see the filesystem events for this cookie file. + * + * Creating the cookie lets us guarantee that our FS listener + * thread has drained the kernel queue and we are caught up + * with the kernel. + * + * If we cannot create the cookie (or otherwise guarantee that + * we are caught up), we send a trivial response. We have to + * assume that there might be some very, very recent activity + * on the FS still in flight. + */ + if (do_cookie) { + cookie_result = with_lock__wait_for_cookie(state); + if (cookie_result != FCIR_SEEN) { + error(_("fsmonitor: cookie_result '%d' != SEEN"), + cookie_result); + do_trivial = 1; + } + } + if (do_flush) with_lock__do_force_resync(state); @@ -787,7 +975,9 @@ static int handle_client(void *data, return result; } -#define FSMONITOR_COOKIE_PREFIX ".fsmonitor-daemon-" +#define FSMONITOR_DIR "fsmonitor--daemon" +#define FSMONITOR_COOKIE_DIR "cookies" +#define FSMONITOR_COOKIE_PREFIX (FSMONITOR_DIR "/" FSMONITOR_COOKIE_DIR "/") enum fsmonitor_path_type fsmonitor_classify_path_workdir_relative( const char *rel) @@ -940,6 +1130,9 @@ void fsmonitor_publish(struct fsmonitor_daemon_state *state, } } + if (cookie_names->nr) + with_lock__mark_cookies_seen(state, cookie_names); + pthread_mutex_unlock(&state->main_lock); } @@ -1031,7 +1224,9 @@ static int fsmonitor_run_daemon(void) memset(&state, 0, sizeof(state)); + hashmap_init(&state.cookies, cookies_cmp, NULL, 0); pthread_mutex_init(&state.main_lock, NULL); + pthread_cond_init(&state.cookies_cond, NULL); state.error_code = 0; state.current_token_data = fsmonitor_new_token_data(); @@ -1057,6 +1252,44 @@ static int fsmonitor_run_daemon(void) } /* + * We will write filesystem syncing cookie files into + * <gitdir>/<fsmonitor-dir>/<cookie-dir>/<pid>-<seq>. + * + * The extra layers of subdirectories here keep us from + * changing the mtime on ".git/" or ".git/foo/" when we create + * or delete cookie files. + * + * There have been problems with some IDEs that do a + * non-recursive watch of the ".git/" directory and run a + * series of commands any time something happens. + * + * For example, if we place our cookie files directly in + * ".git/" or ".git/foo/" then a `git status` (or similar + * command) from the IDE will cause a cookie file to be + * created in one of those dirs. This causes the mtime of + * those dirs to change. This triggers the IDE's watch + * notification. This triggers the IDE to run those commands + * again. And the process repeats and the machine never goes + * idle. + * + * Adding the extra layers of subdirectories prevents the + * mtime of ".git/" and ".git/foo" from changing when a + * cookie file is created. + */ + strbuf_init(&state.path_cookie_prefix, 0); + strbuf_addbuf(&state.path_cookie_prefix, &state.path_gitdir_watch); + + strbuf_addch(&state.path_cookie_prefix, '/'); + strbuf_addstr(&state.path_cookie_prefix, FSMONITOR_DIR); + mkdir(state.path_cookie_prefix.buf, 0777); + + strbuf_addch(&state.path_cookie_prefix, '/'); + strbuf_addstr(&state.path_cookie_prefix, FSMONITOR_COOKIE_DIR); + mkdir(state.path_cookie_prefix.buf, 0777); + + strbuf_addch(&state.path_cookie_prefix, '/'); + + /* * Confirm that we can create platform-specific resources for the * filesystem listener before we bother starting all the threads. */ @@ -1068,6 +1301,7 @@ static int fsmonitor_run_daemon(void) err = fsmonitor_run_daemon_1(&state); done: + pthread_cond_destroy(&state.cookies_cond); pthread_mutex_destroy(&state.main_lock); fsm_listen__dtor(&state); @@ -1075,6 +1309,7 @@ done: strbuf_release(&state.path_worktree_watch); strbuf_release(&state.path_gitdir_watch); + strbuf_release(&state.path_cookie_prefix); return err; } diff --git a/fsmonitor--daemon.h b/fsmonitor--daemon.h index 010fbfe60e..bd09fffc17 100644 --- a/fsmonitor--daemon.h +++ b/fsmonitor--daemon.h @@ -45,6 +45,11 @@ struct fsmonitor_daemon_state { struct fsmonitor_token_data *current_token_data; + struct strbuf path_cookie_prefix; + pthread_cond_t cookies_cond; + int cookie_seq; + struct hashmap cookies; + int error_code; struct fsmonitor_daemon_backend_data *backend_data; |