diff options
Diffstat (limited to 'builtin/fsmonitor--daemon.c')
| -rw-r--r-- | builtin/fsmonitor--daemon.c | 1479 |
1 files changed, 1479 insertions, 0 deletions
diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c new file mode 100644 index 0000000..46be55a --- /dev/null +++ b/builtin/fsmonitor--daemon.c @@ -0,0 +1,1479 @@ +#include "builtin.h" +#include "config.h" +#include "parse-options.h" +#include "fsmonitor.h" +#include "fsmonitor-ipc.h" +#include "compat/fsmonitor/fsm-listen.h" +#include "fsmonitor--daemon.h" +#include "simple-ipc.h" +#include "khash.h" +#include "pkt-line.h" + +static const char * const builtin_fsmonitor__daemon_usage[] = { + N_("git fsmonitor--daemon start [<options>]"), + N_("git fsmonitor--daemon run [<options>]"), + N_("git fsmonitor--daemon stop"), + N_("git fsmonitor--daemon status"), + NULL +}; + +#ifdef HAVE_FSMONITOR_DAEMON_BACKEND +/* + * Global state loaded from config. + */ +#define FSMONITOR__IPC_THREADS "fsmonitor.ipcthreads" +static int fsmonitor__ipc_threads = 8; + +#define FSMONITOR__START_TIMEOUT "fsmonitor.starttimeout" +static int fsmonitor__start_timeout_sec = 60; + +#define FSMONITOR__ANNOUNCE_STARTUP "fsmonitor.announcestartup" +static int fsmonitor__announce_startup = 0; + +static int fsmonitor_config(const char *var, const char *value, void *cb) +{ + if (!strcmp(var, FSMONITOR__IPC_THREADS)) { + int i = git_config_int(var, value); + if (i < 1) + return error(_("value of '%s' out of range: %d"), + FSMONITOR__IPC_THREADS, i); + fsmonitor__ipc_threads = i; + return 0; + } + + if (!strcmp(var, FSMONITOR__START_TIMEOUT)) { + int i = git_config_int(var, value); + if (i < 0) + return error(_("value of '%s' out of range: %d"), + FSMONITOR__START_TIMEOUT, i); + fsmonitor__start_timeout_sec = i; + return 0; + } + + if (!strcmp(var, FSMONITOR__ANNOUNCE_STARTUP)) { + int is_bool; + int i = git_config_bool_or_int(var, value, &is_bool); + if (i < 0) + return error(_("value of '%s' not bool or int: %d"), + var, i); + fsmonitor__announce_startup = i; + return 0; + } + + return git_default_config(var, value, cb); +} + +/* + * Acting as a CLIENT. + * + * Send a "quit" command to the `git-fsmonitor--daemon` (if running) + * and wait for it to shutdown. + */ +static int do_as_client__send_stop(void) +{ + struct strbuf answer = STRBUF_INIT; + int ret; + + ret = fsmonitor_ipc__send_command("quit", &answer); + + /* The quit command does not return any response data. */ + strbuf_release(&answer); + + if (ret) + return ret; + + trace2_region_enter("fsm_client", "polling-for-daemon-exit", NULL); + while (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING) + sleep_millisec(50); + trace2_region_leave("fsm_client", "polling-for-daemon-exit", NULL); + + return 0; +} + +static int do_as_client__status(void) +{ + enum ipc_active_state state = fsmonitor_ipc__get_state(); + + switch (state) { + case IPC_STATE__LISTENING: + printf(_("fsmonitor-daemon is watching '%s'\n"), + the_repository->worktree); + return 0; + + default: + printf(_("fsmonitor-daemon is not watching '%s'\n"), + the_repository->worktree); + return 1; + } +} + +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 + * created/deleted/modified files relative to a token. In the response, + * clients receive a new token for the next (relative) request. + * + * + * Token Format + * ============ + * + * The contents of the token are private and provider-specific. + * + * For the built-in fsmonitor--daemon, we define a token as follows: + * + * "builtin" ":" <token_id> ":" <sequence_nr> + * + * The "builtin" prefix is used as a namespace to avoid conflicts + * with other providers (such as Watchman). + * + * The <token_id> is an arbitrary OPAQUE string, such as a GUID, + * UUID, or {timestamp,pid}. It is used to group all filesystem + * events that happened while the daemon was monitoring (and in-sync + * with the filesystem). + * + * Unlike FSMonitor Protocol V1, it is not defined as a timestamp + * and does not define less-than/greater-than relationships. + * (There are too many race conditions to rely on file system + * event timestamps.) + * + * The <sequence_nr> is a simple integer incremented whenever the + * daemon needs to make its state public. For example, if 1000 file + * system events come in, but no clients have requested the data, + * the daemon can continue to accumulate file changes in the same + * bin and does not need to advance the sequence number. However, + * as soon as a client does arrive, the daemon needs to start a new + * bin and increment the sequence number. + * + * The sequence number serves as the boundary between 2 sets + * of bins -- the older ones that the client has already seen + * and the newer ones that it hasn't. + * + * When a new <token_id> is created, the <sequence_nr> is reset to + * zero. + * + * + * About Token Ids + * =============== + * + * A new token_id is created: + * + * [1] each time the daemon is started. + * + * [2] any time that the daemon must re-sync with the filesystem + * (such as when the kernel drops or we miss events on a very + * active volume). + * + * [3] in response to a client "flush" command (for dropped event + * testing). + * + * When a new token_id is created, the daemon is free to discard all + * cached filesystem events associated with any previous token_ids. + * Events associated with a non-current token_id will never be sent + * to a client. A token_id change implicitly means that the daemon + * has gap in its event history. + * + * Therefore, clients that present a token with a stale (non-current) + * token_id will always be given a trivial response. + */ +struct fsmonitor_token_data { + struct strbuf token_id; + struct fsmonitor_batch *batch_head; + struct fsmonitor_batch *batch_tail; + uint64_t client_ref_count; +}; + +struct fsmonitor_batch { + struct fsmonitor_batch *next; + uint64_t batch_seq_nr; + const char **interned_paths; + size_t nr, alloc; + time_t pinned_time; +}; + +static struct fsmonitor_token_data *fsmonitor_new_token_data(void) +{ + static int test_env_value = -1; + static uint64_t flush_count = 0; + struct fsmonitor_token_data *token; + struct fsmonitor_batch *batch; + + CALLOC_ARRAY(token, 1); + batch = fsmonitor_batch__new(); + + strbuf_init(&token->token_id, 0); + token->batch_head = batch; + token->batch_tail = batch; + token->client_ref_count = 0; + + if (test_env_value < 0) + test_env_value = git_env_bool("GIT_TEST_FSMONITOR_TOKEN", 0); + + if (!test_env_value) { + struct timeval tv; + struct tm tm; + time_t secs; + + gettimeofday(&tv, NULL); + secs = tv.tv_sec; + gmtime_r(&secs, &tm); + + strbuf_addf(&token->token_id, + "%"PRIu64".%d.%4d%02d%02dT%02d%02d%02d.%06ldZ", + flush_count++, + getpid(), + tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, + tm.tm_hour, tm.tm_min, tm.tm_sec, + (long)tv.tv_usec); + } else { + strbuf_addf(&token->token_id, "test_%08x", test_env_value++); + } + + /* + * We created a new <token_id> and are starting a new series + * of tokens with a zero <seq_nr>. + * + * Since clients cannot guess our new (non test) <token_id> + * they will always receive a trivial response (because of the + * mismatch on the <token_id>). The trivial response will + * tell them our new <token_id> so that subsequent requests + * will be relative to our new series. (And when sending that + * response, we pin the current head of the batch list.) + * + * Even if the client correctly guesses the <token_id>, their + * request of "builtin:<token_id>:0" asks for all changes MORE + * RECENT than batch/bin 0. + * + * This implies that it is a waste to accumulate paths in the + * initial batch/bin (because they will never be transmitted). + * + * So the daemon could be running for days and watching the + * file system, but doesn't need to actually accumulate any + * paths UNTIL we need to set a reference point for a later + * relative request. + * + * However, it is very useful for testing to always have a + * reference point set. Pin batch 0 to force early file system + * events to accumulate. + */ + if (test_env_value) + batch->pinned_time = time(NULL); + + return token; +} + +struct fsmonitor_batch *fsmonitor_batch__new(void) +{ + struct fsmonitor_batch *batch; + + CALLOC_ARRAY(batch, 1); + + return batch; +} + +void fsmonitor_batch__free_list(struct fsmonitor_batch *batch) +{ + while (batch) { + struct fsmonitor_batch *next = batch->next; + + /* + * The actual strings within the array of this batch + * are interned, so we don't own them. We only own + * the array. + */ + free(batch->interned_paths); + free(batch); + + batch = next; + } +} + +void fsmonitor_batch__add_path(struct fsmonitor_batch *batch, + const char *path) +{ + const char *interned_path = strintern(path); + + trace_printf_key(&trace_fsmonitor, "event: %s", interned_path); + + ALLOC_GROW(batch->interned_paths, batch->nr + 1, batch->alloc); + batch->interned_paths[batch->nr++] = interned_path; +} + +static void fsmonitor_batch__combine(struct fsmonitor_batch *batch_dest, + const struct fsmonitor_batch *batch_src) +{ + size_t k; + + ALLOC_GROW(batch_dest->interned_paths, + batch_dest->nr + batch_src->nr + 1, + batch_dest->alloc); + + for (k = 0; k < batch_src->nr; k++) + batch_dest->interned_paths[batch_dest->nr++] = + batch_src->interned_paths[k]; +} + +/* + * To keep the batch list from growing unbounded in response to filesystem + * activity, we try to truncate old batches from the end of the list as + * they become irrelevant. + * + * We assume that the .git/index will be updated with the most recent token + * any time the index is updated. And future commands will only ask for + * recent changes *since* that new token. So as tokens advance into the + * future, older batch items will never be requested/needed. So we can + * truncate them without loss of functionality. + * + * However, multiple commands may be talking to the daemon concurrently + * or perform a slow command, so a little "token skew" is possible. + * Therefore, we want this to be a little bit lazy and have a generous + * delay. + * + * The current reader thread walked backwards in time from `token->batch_head` + * back to `batch_marker` somewhere in the middle of the batch list. + * + * Let's walk backwards in time from that marker an arbitrary delay + * and truncate the list there. Note that these timestamps are completely + * artificial (based on when we pinned the batch item) and not on any + * filesystem activity. + * + * Return the obsolete portion of the list after we have removed it from + * the official list so that the caller can free it after leaving the lock. + */ +#define MY_TIME_DELAY_SECONDS (5 * 60) /* seconds */ + +static struct fsmonitor_batch *with_lock__truncate_old_batches( + struct fsmonitor_daemon_state *state, + const struct fsmonitor_batch *batch_marker) +{ + /* assert current thread holding state->main_lock */ + + const struct fsmonitor_batch *batch; + struct fsmonitor_batch *remainder; + + if (!batch_marker) + return NULL; + + trace_printf_key(&trace_fsmonitor, "Truncate: mark (%"PRIu64",%"PRIu64")", + batch_marker->batch_seq_nr, + (uint64_t)batch_marker->pinned_time); + + for (batch = batch_marker; batch; batch = batch->next) { + time_t t; + + if (!batch->pinned_time) /* an overflow batch */ + continue; + + t = batch->pinned_time + MY_TIME_DELAY_SECONDS; + if (t > batch_marker->pinned_time) /* too close to marker */ + continue; + + goto truncate_past_here; + } + + return NULL; + +truncate_past_here: + state->current_token_data->batch_tail = (struct fsmonitor_batch *)batch; + + remainder = ((struct fsmonitor_batch *)batch)->next; + ((struct fsmonitor_batch *)batch)->next = NULL; + + return remainder; +} + +static void fsmonitor_free_token_data(struct fsmonitor_token_data *token) +{ + if (!token) + return; + + assert(token->client_ref_count == 0); + + strbuf_release(&token->token_id); + + fsmonitor_batch__free_list(token->batch_head); + + free(token); +} + +/* + * Flush all of our cached data about the filesystem. Call this if we + * lose sync with the filesystem and miss some notification events. + * + * [1] If we are missing events, then we no longer have a complete + * history of the directory (relative to our current start 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. + * + * Either way, the old token data series is no longer associated with + * our state data. + */ +static void with_lock__do_force_resync(struct fsmonitor_daemon_state *state) +{ + /* assert current thread holding state->main_lock */ + + struct fsmonitor_token_data *free_me = NULL; + struct fsmonitor_token_data *new_one = NULL; + + new_one = fsmonitor_new_token_data(); + + if (state->current_token_data->client_ref_count == 0) + free_me = state->current_token_data; + 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) +{ + pthread_mutex_lock(&state->main_lock); + with_lock__do_force_resync(state); + pthread_mutex_unlock(&state->main_lock); +} + +/* + * Format an opaque token string to send to the client. + */ +static void with_lock__format_response_token( + struct strbuf *response_token, + const struct strbuf *response_token_id, + const struct fsmonitor_batch *batch) +{ + /* assert current thread holding state->main_lock */ + + strbuf_reset(response_token); + strbuf_addf(response_token, "builtin:%s:%"PRIu64, + response_token_id->buf, batch->batch_seq_nr); +} + +/* + * Parse an opaque token from the client. + * Returns -1 on error. + */ +static int fsmonitor_parse_client_token(const char *buf_token, + struct strbuf *requested_token_id, + uint64_t *seq_nr) +{ + const char *p; + char *p_end; + + strbuf_reset(requested_token_id); + *seq_nr = 0; + + if (!skip_prefix(buf_token, "builtin:", &p)) + return -1; + + while (*p && *p != ':') + strbuf_addch(requested_token_id, *p++); + if (!*p++) + return -1; + + *seq_nr = (uint64_t)strtoumax(p, &p_end, 10); + if (*p_end) + return -1; + + return 0; +} + +KHASH_INIT(str, const char *, int, 0, kh_str_hash_func, kh_str_hash_equal) + +static int do_handle_client(struct fsmonitor_daemon_state *state, + const char *command, + ipc_server_reply_cb *reply, + struct ipc_server_reply_data *reply_data) +{ + struct fsmonitor_token_data *token_data = NULL; + struct strbuf response_token = STRBUF_INIT; + struct strbuf requested_token_id = STRBUF_INIT; + struct strbuf payload = STRBUF_INIT; + uint64_t requested_oldest_seq_nr = 0; + uint64_t total_response_len = 0; + const char *p; + const struct fsmonitor_batch *batch_head; + const struct fsmonitor_batch *batch; + struct fsmonitor_batch *remainder = NULL; + intmax_t count = 0, duplicates = 0; + kh_str_t *shown; + 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: + * + * <command> := quit NUL + * | flush NUL + * | <V1-time-since-epoch-ns> NUL + * | <V2-opaque-fsmonitor-token> NUL + */ + + if (!strcmp(command, "quit")) { + /* + * A client has requested over the socket/pipe that the + * daemon shutdown. + * + * Tell the IPC thread pool to shutdown (which completes + * the await in the main thread (which can stop the + * fsmonitor listener thread)). + * + * There is no reply to the client. + */ + return SIMPLE_IPC_QUIT; + + } else if (!strcmp(command, "flush")) { + /* + * Flush all of our cached data and generate a new token + * just like if we lost sync with the filesystem. + * + * Then send a trivial response using the new token. + */ + do_flush = 1; + do_trivial = 1; + + } else if (!skip_prefix(command, "builtin:", &p)) { + /* assume V1 timestamp or garbage */ + + char *p_end; + + strtoumax(command, &p_end, 10); + trace_printf_key(&trace_fsmonitor, + ((*p_end) ? + "fsmonitor: invalid command line '%s'" : + "fsmonitor: unsupported V1 protocol '%s'"), + command); + do_trivial = 1; + + } else { + /* We have "builtin:*" */ + if (fsmonitor_parse_client_token(command, &requested_token_id, + &requested_oldest_seq_nr)) { + trace_printf_key(&trace_fsmonitor, + "fsmonitor: invalid V2 protocol token '%s'", + command); + do_trivial = 1; + + } else { + /* + * We have a V2 valid token: + * "builtin:<token_id>:<seq_nr>" + */ + do_cookie = 1; + } + } + + pthread_mutex_lock(&state->main_lock); + + 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); + + /* + * We mark the current head of the batch list as "pinned" so + * that the listener thread will treat this item as read-only + * (and prevent any more paths from being added to it) from + * now on. + */ + token_data = state->current_token_data; + batch_head = token_data->batch_head; + ((struct fsmonitor_batch *)batch_head)->pinned_time = time(NULL); + + /* + * FSMonitor Protocol V2 requires that we send a response header + * with a "new current token" and then all of the paths that changed + * since the "requested token". We send the seq_nr of the just-pinned + * head batch so that future requests from a client will be relative + * to it. + */ + with_lock__format_response_token(&response_token, + &token_data->token_id, batch_head); + + reply(reply_data, response_token.buf, response_token.len + 1); + total_response_len += response_token.len + 1; + + trace2_data_string("fsmonitor", the_repository, "response/token", + response_token.buf); + trace_printf_key(&trace_fsmonitor, "response token: %s", + response_token.buf); + + if (!do_trivial) { + if (strcmp(requested_token_id.buf, token_data->token_id.buf)) { + /* + * The client last spoke to a different daemon + * instance -OR- the daemon had to resync with + * the filesystem (and lost events), so reject. + */ + trace2_data_string("fsmonitor", the_repository, + "response/token", "different"); + do_trivial = 1; + + } else if (requested_oldest_seq_nr < + token_data->batch_tail->batch_seq_nr) { + /* + * The client wants older events than we have for + * this token_id. This means that the end of our + * batch list was truncated and we cannot give the + * client a complete snapshot relative to their + * request. + */ + trace_printf_key(&trace_fsmonitor, + "client requested truncated data"); + do_trivial = 1; + } + } + + if (do_trivial) { + pthread_mutex_unlock(&state->main_lock); + + reply(reply_data, "/", 2); + + trace2_data_intmax("fsmonitor", the_repository, + "response/trivial", 1); + + goto cleanup; + } + + /* + * We're going to hold onto a pointer to the current + * token-data while we walk the list of batches of files. + * During this time, we will NOT be under the lock. + * So we ref-count it. + * + * This allows the listener thread to continue prepending + * new batches of items to the token-data (which we'll ignore). + * + * AND it allows the listener thread to do a token-reset + * (and install a new `current_token_data`). + */ + token_data->client_ref_count++; + + pthread_mutex_unlock(&state->main_lock); + + /* + * The client request is relative to the token that they sent, + * so walk the batch list backwards from the current head back + * to the batch (sequence number) they named. + * + * We use khash to de-dup the list of pathnames. + * + * NEEDSWORK: each batch contains a list of interned strings, + * so we only need to do pointer comparisons here to build the + * hash table. Currently, we're still comparing the string + * values. + */ + shown = kh_init_str(); + for (batch = batch_head; + batch && batch->batch_seq_nr > requested_oldest_seq_nr; + batch = batch->next) { + size_t k; + + for (k = 0; k < batch->nr; k++) { + const char *s = batch->interned_paths[k]; + size_t s_len; + + if (kh_get_str(shown, s) != kh_end(shown)) + duplicates++; + else { + kh_put_str(shown, s, &hash_ret); + + trace_printf_key(&trace_fsmonitor, + "send[%"PRIuMAX"]: %s", + count, s); + + /* Each path gets written with a trailing NUL */ + s_len = strlen(s) + 1; + + if (payload.len + s_len >= + LARGE_PACKET_DATA_MAX) { + reply(reply_data, payload.buf, + payload.len); + total_response_len += payload.len; + strbuf_reset(&payload); + } + + strbuf_add(&payload, s, s_len); + count++; + } + } + } + + if (payload.len) { + reply(reply_data, payload.buf, payload.len); + total_response_len += payload.len; + } + + kh_release_str(shown); + + pthread_mutex_lock(&state->main_lock); + + if (token_data->client_ref_count > 0) + token_data->client_ref_count--; + + if (token_data->client_ref_count == 0) { + if (token_data != state->current_token_data) { + /* + * The listener thread did a token-reset while we were + * walking the batch list. Therefore, this token is + * stale and can be discarded completely. If we are + * the last reader thread using this token, we own + * that work. + */ + fsmonitor_free_token_data(token_data); + } else if (batch) { + /* + * We are holding the lock and are the only + * reader of the ref-counted portion of the + * list, so we get the honor of seeing if the + * list can be truncated to save memory. + * + * The main loop did not walk to the end of the + * list, so this batch is the first item in the + * batch-list that is older than the requested + * end-point sequence number. See if the tail + * end of the list is obsolete. + */ + remainder = with_lock__truncate_old_batches(state, + batch); + } + } + + pthread_mutex_unlock(&state->main_lock); + + if (remainder) + fsmonitor_batch__free_list(remainder); + + trace2_data_intmax("fsmonitor", the_repository, "response/length", total_response_len); + trace2_data_intmax("fsmonitor", the_repository, "response/count/files", count); + trace2_data_intmax("fsmonitor", the_repository, "response/count/duplicates", duplicates); + +cleanup: + strbuf_release(&response_token); + strbuf_release(&requested_token_id); + strbuf_release(&payload); + + return 0; +} + +static ipc_server_application_cb handle_client; + +static int handle_client(void *data, + const char *command, size_t command_len, + ipc_server_reply_cb *reply, + struct ipc_server_reply_data *reply_data) +{ + struct fsmonitor_daemon_state *state = data; + int result; + + /* + * The Simple IPC API now supports {char*, len} arguments, but + * FSMonitor always uses proper null-terminated strings, so + * we can ignore the command_len argument. (Trust, but verify.) + */ + if (command_len != strlen(command)) + BUG("FSMonitor assumes text messages"); + + trace_printf_key(&trace_fsmonitor, "requested token: %s", command); + + trace2_region_enter("fsmonitor", "handle_client", the_repository); + trace2_data_string("fsmonitor", the_repository, "request", command); + + result = do_handle_client(state, command, reply, reply_data); + + trace2_region_leave("fsmonitor", "handle_client", the_repository); + + return result; +} + +#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) +{ + if (fspathncmp(rel, ".git", 4)) + return IS_WORKDIR_PATH; + rel += 4; + + if (!*rel) + return IS_DOT_GIT; + if (*rel != '/') + return IS_WORKDIR_PATH; /* e.g. .gitignore */ + rel++; + + if (!fspathncmp(rel, FSMONITOR_COOKIE_PREFIX, + strlen(FSMONITOR_COOKIE_PREFIX))) + return IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX; + + return IS_INSIDE_DOT_GIT; +} + +enum fsmonitor_path_type fsmonitor_classify_path_gitdir_relative( + const char *rel) +{ + if (!fspathncmp(rel, FSMONITOR_COOKIE_PREFIX, + strlen(FSMONITOR_COOKIE_PREFIX))) + return IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX; + + return IS_INSIDE_GITDIR; +} + +static enum fsmonitor_path_type try_classify_workdir_abs_path( + struct fsmonitor_daemon_state *state, + const char *path) +{ + const char *rel; + + if (fspathncmp(path, state->path_worktree_watch.buf, + state->path_worktree_watch.len)) + return IS_OUTSIDE_CONE; + + rel = path + state->path_worktree_watch.len; + + if (!*rel) + return IS_WORKDIR_PATH; /* it is the root dir exactly */ + if (*rel != '/') + return IS_OUTSIDE_CONE; + rel++; + + return fsmonitor_classify_path_workdir_relative(rel); +} + +enum fsmonitor_path_type fsmonitor_classify_path_absolute( + struct fsmonitor_daemon_state *state, + const char *path) +{ + const char *rel; + enum fsmonitor_path_type t; + + t = try_classify_workdir_abs_path(state, path); + if (state->nr_paths_watching == 1) + return t; + if (t != IS_OUTSIDE_CONE) + return t; + + if (fspathncmp(path, state->path_gitdir_watch.buf, + state->path_gitdir_watch.len)) + return IS_OUTSIDE_CONE; + + rel = path + state->path_gitdir_watch.len; + + if (!*rel) + return IS_GITDIR; /* it is the <gitdir> exactly */ + if (*rel != '/') + return IS_OUTSIDE_CONE; + rel++; + + return fsmonitor_classify_path_gitdir_relative(rel); +} + +/* + * We try to combine small batches at the front of the batch-list to avoid + * having a long list. This hopefully makes it a little easier when we want + * to truncate and maintain the list. However, we don't want the paths array + * to just keep growing and growing with realloc, so we insert an arbitrary + * limit. + */ +#define MY_COMBINE_LIMIT (1024) + +void fsmonitor_publish(struct fsmonitor_daemon_state *state, + struct fsmonitor_batch *batch, + const struct string_list *cookie_names) +{ + if (!batch && !cookie_names->nr) + return; + + pthread_mutex_lock(&state->main_lock); + + if (batch) { + struct fsmonitor_batch *head; + + head = state->current_token_data->batch_head; + if (!head) { + BUG("token does not have batch"); + } else if (head->pinned_time) { + /* + * We cannot alter the current batch list + * because: + * + * [a] it is being transmitted to at least one + * client and the handle_client() thread has a + * ref-count, but not a lock on the batch list + * starting with this item. + * + * [b] it has been transmitted in the past to + * at least one client such that future + * requests are relative to this head batch. + * + * So, we can only prepend a new batch onto + * the front of the list. + */ + batch->batch_seq_nr = head->batch_seq_nr + 1; + batch->next = head; + state->current_token_data->batch_head = batch; + } else if (!head->batch_seq_nr) { + /* + * Batch 0 is unpinned. See the note in + * `fsmonitor_new_token_data()` about why we + * don't need to accumulate these paths. + */ + fsmonitor_batch__free_list(batch); + } else if (head->nr + batch->nr > MY_COMBINE_LIMIT) { + /* + * The head batch in the list has never been + * transmitted to a client, but folding the + * contents of the new batch onto it would + * exceed our arbitrary limit, so just prepend + * the new batch onto the list. + */ + batch->batch_seq_nr = head->batch_seq_nr + 1; + batch->next = head; + state->current_token_data->batch_head = batch; + } else { + /* + * We are free to add the paths in the given + * batch onto the end of the current head batch. + */ + fsmonitor_batch__combine(head, batch); + fsmonitor_batch__free_list(batch); + } + } + + if (cookie_names->nr) + with_lock__mark_cookies_seen(state, cookie_names); + + pthread_mutex_unlock(&state->main_lock); +} + +static void *fsm_listen__thread_proc(void *_state) +{ + struct fsmonitor_daemon_state *state = _state; + + trace2_thread_start("fsm-listen"); + + trace_printf_key(&trace_fsmonitor, "Watching: worktree '%s'", + state->path_worktree_watch.buf); + if (state->nr_paths_watching > 1) + trace_printf_key(&trace_fsmonitor, "Watching: gitdir '%s'", + state->path_gitdir_watch.buf); + + fsm_listen__loop(state); + + pthread_mutex_lock(&state->main_lock); + if (state->current_token_data && + state->current_token_data->client_ref_count == 0) + fsmonitor_free_token_data(state->current_token_data); + state->current_token_data = NULL; + pthread_mutex_unlock(&state->main_lock); + + trace2_thread_exit(); + return NULL; +} + +static int fsmonitor_run_daemon_1(struct fsmonitor_daemon_state *state) +{ + struct ipc_server_opts ipc_opts = { + .nr_threads = fsmonitor__ipc_threads, + + /* + * We know that there are no other active threads yet, + * so we can let the IPC layer temporarily chdir() if + * it needs to when creating the server side of the + * Unix domain socket. + */ + .uds_disallow_chdir = 0 + }; + + /* + * Start the IPC thread pool before the we've started the file + * system event listener thread so that we have the IPC handle + * before we need it. + */ + if (ipc_server_run_async(&state->ipc_server_data, + fsmonitor_ipc__get_path(), &ipc_opts, + handle_client, state)) + return error_errno( + _("could not start IPC thread pool on '%s'"), + fsmonitor_ipc__get_path()); + + /* + * Start the fsmonitor listener thread to collect filesystem + * events. + */ + if (pthread_create(&state->listener_thread, NULL, + fsm_listen__thread_proc, state) < 0) { + ipc_server_stop_async(state->ipc_server_data); + ipc_server_await(state->ipc_server_data); + + return error(_("could not start fsmonitor listener thread")); + } + + /* + * The daemon is now fully functional in background threads. + * Wait for the IPC thread pool to shutdown (whether by client + * request or from filesystem activity). + */ + ipc_server_await(state->ipc_server_data); + + /* + * The fsmonitor listener thread may have received a shutdown + * event from the IPC thread pool, but it doesn't hurt to tell + * it again. And wait for it to shutdown. + */ + fsm_listen__stop_async(state); + pthread_join(state->listener_thread, NULL); + + return state->error_code; +} + +static int fsmonitor_run_daemon(void) +{ + struct fsmonitor_daemon_state state; + int err; + + 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(); + + /* Prepare to (recursively) watch the <worktree-root> directory. */ + strbuf_init(&state.path_worktree_watch, 0); + strbuf_addstr(&state.path_worktree_watch, absolute_path(get_git_work_tree())); + state.nr_paths_watching = 1; + + /* + * We create and delete cookie files somewhere inside the .git + * directory to help us keep sync with the file system. If + * ".git" is not a directory, then <gitdir> is not inside the + * cone of <worktree-root>, so set up a second watch to watch + * the <gitdir> so that we get events for the cookie files. + */ + strbuf_init(&state.path_gitdir_watch, 0); + strbuf_addbuf(&state.path_gitdir_watch, &state.path_worktree_watch); + strbuf_addstr(&state.path_gitdir_watch, "/.git"); + if (!is_directory(state.path_gitdir_watch.buf)) { + strbuf_reset(&state.path_gitdir_watch); + strbuf_addstr(&state.path_gitdir_watch, absolute_path(get_git_dir())); + state.nr_paths_watching = 2; + } + + /* + * 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. + */ + if (fsm_listen__ctor(&state)) { + err = error(_("could not initialize listener thread")); + goto done; + } + + err = fsmonitor_run_daemon_1(&state); + +done: + pthread_cond_destroy(&state.cookies_cond); + pthread_mutex_destroy(&state.main_lock); + fsm_listen__dtor(&state); + + ipc_server_free(state.ipc_server_data); + + strbuf_release(&state.path_worktree_watch); + strbuf_release(&state.path_gitdir_watch); + strbuf_release(&state.path_cookie_prefix); + + return err; +} + +static int try_to_run_foreground_daemon(int detach_console) +{ + /* + * Technically, we don't need to probe for an existing daemon + * process, since we could just call `fsmonitor_run_daemon()` + * and let it fail if the pipe/socket is busy. + * + * However, this method gives us a nicer error message for a + * common error case. + */ + if (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING) + die(_("fsmonitor--daemon is already running '%s'"), + the_repository->worktree); + + if (fsmonitor__announce_startup) { + fprintf(stderr, _("running fsmonitor-daemon in '%s'\n"), + the_repository->worktree); + fflush(stderr); + } + +#ifdef GIT_WINDOWS_NATIVE + if (detach_console) + FreeConsole(); +#endif + + return !!fsmonitor_run_daemon(); +} + +static start_bg_wait_cb bg_wait_cb; + +static int bg_wait_cb(const struct child_process *cp, void *cb_data) +{ + enum ipc_active_state s = fsmonitor_ipc__get_state(); + + switch (s) { + case IPC_STATE__LISTENING: + /* child is "ready" */ + return 0; + + case IPC_STATE__NOT_LISTENING: + case IPC_STATE__PATH_NOT_FOUND: + /* give child more time */ + return 1; + + default: + case IPC_STATE__INVALID_PATH: + case IPC_STATE__OTHER_ERROR: + /* all the time in world won't help */ + return -1; + } +} + +static int try_to_start_background_daemon(void) +{ + struct child_process cp = CHILD_PROCESS_INIT; + enum start_bg_result sbgr; + + /* + * Before we try to create a background daemon process, see + * if a daemon process is already listening. This makes it + * easier for us to report an already-listening error to the + * console, since our spawn/daemon can only report the success + * of creating the background process (and not whether it + * immediately exited). + */ + if (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING) + die(_("fsmonitor--daemon is already running '%s'"), + the_repository->worktree); + + if (fsmonitor__announce_startup) { + fprintf(stderr, _("starting fsmonitor-daemon in '%s'\n"), + the_repository->worktree); + fflush(stderr); + } + + cp.git_cmd = 1; + + strvec_push(&cp.args, "fsmonitor--daemon"); + strvec_push(&cp.args, "run"); + strvec_push(&cp.args, "--detach"); + strvec_pushf(&cp.args, "--ipc-threads=%d", fsmonitor__ipc_threads); + + cp.no_stdin = 1; + cp.no_stdout = 1; + cp.no_stderr = 1; + + sbgr = start_bg_command(&cp, bg_wait_cb, NULL, + fsmonitor__start_timeout_sec); + + switch (sbgr) { + case SBGR_READY: + return 0; + + default: + case SBGR_ERROR: + case SBGR_CB_ERROR: + return error(_("daemon failed to start")); + + case SBGR_TIMEOUT: + return error(_("daemon not online yet")); + + case SBGR_DIED: + return error(_("daemon terminated")); + } +} + +int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix) +{ + const char *subcmd; + int detach_console = 0; + + struct option options[] = { + OPT_BOOL(0, "detach", &detach_console, N_("detach from console")), + OPT_INTEGER(0, "ipc-threads", + &fsmonitor__ipc_threads, + N_("use <n> ipc worker threads")), + OPT_INTEGER(0, "start-timeout", + &fsmonitor__start_timeout_sec, + N_("max seconds to wait for background daemon startup")), + + OPT_END() + }; + + git_config(fsmonitor_config, NULL); + + argc = parse_options(argc, argv, prefix, options, + builtin_fsmonitor__daemon_usage, 0); + if (argc != 1) + usage_with_options(builtin_fsmonitor__daemon_usage, options); + subcmd = argv[0]; + + if (fsmonitor__ipc_threads < 1) + die(_("invalid 'ipc-threads' value (%d)"), + fsmonitor__ipc_threads); + + if (!strcmp(subcmd, "start")) + return !!try_to_start_background_daemon(); + + if (!strcmp(subcmd, "run")) + return !!try_to_run_foreground_daemon(detach_console); + + if (!strcmp(subcmd, "stop")) + return !!do_as_client__send_stop(); + + if (!strcmp(subcmd, "status")) + return !!do_as_client__status(); + + die(_("Unhandled subcommand '%s'"), subcmd); +} + +#else +int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix) +{ + struct option options[] = { + OPT_END() + }; + + if (argc == 2 && !strcmp(argv[1], "-h")) + usage_with_options(builtin_fsmonitor__daemon_usage, options); + + die(_("fsmonitor--daemon not supported on this platform")); +} +#endif |