From patchwork Fri Feb 11 20:56:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Hostetler X-Patchwork-Id: 12743859 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41138C4332F for ; Fri, 11 Feb 2022 20:57:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243705AbiBKU5E (ORCPT ); Fri, 11 Feb 2022 15:57:04 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:49684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353554AbiBKU4g (ORCPT ); Fri, 11 Feb 2022 15:56:36 -0500 Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E023D51 for ; Fri, 11 Feb 2022 12:56:34 -0800 (PST) Received: by mail-wr1-x42b.google.com with SMTP id u1so3425169wrg.11 for ; Fri, 11 Feb 2022 12:56:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=hHeN/yyKhvcQd7il3lGM3UdFp1D0Y0rF9c0t+mtOVgA=; b=BbKedNI6Sj2iIutW1kQzkW+2thC95VkOcy0GTxB14b8g8aoPCw6Zw5D7v5y2sGbU8l KSNYYmPAuElKUylEmW0mj2EEGhiOX5Hai+eJIWQIu//M0Q1BCi9+76fuPCi85q2/9ZDc chEn4KlRRaRZ23SjeDSU0KtorOMN6b5PCsjSNAWJzdQYDD7ZglUEsdwKzVzKkJsoN5tu 19PswnW3AmqIpr22oTrNnWWpPUjw1O4F3tJW1Orl2PNNy35lRda8xj7PsdfLn7Outrs+ fV6elZnIypK2eWVqflcmZ8hLpRThuWiLQyVlCWs9QOj/7o1EKCger4M8A/a9p1+4w9y7 m+ZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=hHeN/yyKhvcQd7il3lGM3UdFp1D0Y0rF9c0t+mtOVgA=; b=4InMwA3C1XScoKkgfBvWlvUJCgT8Bcgp7F8bcUw7EhQFJiM2W2Hx7QLydjGVwGjZDx wNTOmFgnqLjrYsBRAggsSOQ7VF/eLCiSpWTWCgWi9+8DA3qOaOKAKliZ8tru3P4RCe7f TA56oBR24xvte8bKLF6tKM8LttZqnhhNseC7VOVjHMypb5rxE0hOx5YZK3nyUzvqseSe cuGE37WNHAl+1JHWAQvN2uJezE9nF+gSGL6SO+/kTVWk1AAMvbS6QJ1gs2Uewy5uT79x y3Fj7lQ7bCGwBoCXNP2BdeZfXoL1UpHvP2qaYw5PYmqBkuBbOEZkGN8cbjB6UL2dxE8O 4Hww== X-Gm-Message-State: AOAM532dC+rpYJunJcQBtDVX0TBNvb1h4WK90uWOuKuULt2zvJ3Nwphz y7vOAseR1KNU1dEGpJtRQY/K7x+Oj4E= X-Google-Smtp-Source: ABdhPJyXoPeW9qk6k1Wvj4+CRR/V5qgS3f1hR1RpzVnyLII3RKp2jdGK+ApYfZ8WN++cjMQOH95fsw== X-Received: by 2002:adf:dd10:: with SMTP id a16mr2665332wrm.288.1644612992415; Fri, 11 Feb 2022 12:56:32 -0800 (PST) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id bg26sm5412706wmb.48.2022.02.11.12.56.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Feb 2022 12:56:31 -0800 (PST) Message-Id: <8d1db6444091e17041f6a649131c2e8705365c95.1644612979.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Fri, 11 Feb 2022 20:56:03 +0000 Subject: [PATCH v5 14/30] fsmonitor--daemon: create token-based changed path cache Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Bagas Sanjaya , =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason , Jeff Hostetler , Eric Sunshine , Jeff Hostetler , Jeff Hostetler Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Jeff Hostetler From: Jeff Hostetler Teach fsmonitor--daemon to build a list of changed paths and associate them with a token-id. This will be used by the platform-specific backends to accumulate changed paths in response to filesystem events. The platform-specific file system listener thread receives file system events containing one or more changed pathnames (with whatever bucketing or grouping that is convenient for the file system). These paths are accumulated (without locking) by the file system layer into a `fsmonitor_batch`. When the file system layer has drained the kernel event queue, it will "publish" them to our token queue and make them visible to concurrent client worker threads. The token layer is free to combine and/or de-dup paths within these batches for efficient presentation to clients. Signed-off-by: Jeff Hostetler --- builtin/fsmonitor--daemon.c | 230 +++++++++++++++++++++++++++++++++++- fsmonitor--daemon.h | 40 +++++++ 2 files changed, 268 insertions(+), 2 deletions(-) diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c index 2997c2cba8c..34603f23053 100644 --- a/builtin/fsmonitor--daemon.c +++ b/builtin/fsmonitor--daemon.c @@ -168,17 +168,27 @@ struct fsmonitor_token_data { 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 = NULL; - token->batch_tail = NULL; + token->batch_head = batch; + token->batch_tail = batch; token->client_ref_count = 0; if (test_env_value < 0) @@ -204,9 +214,143 @@ static struct fsmonitor_token_data *fsmonitor_new_token_data(void) strbuf_addf(&token->token_id, "test_%08x", test_env_value++); } + /* + * We created a new and are starting a new series + * of tokens with a zero . + * + * Since clients cannot guess our new (non test) + * they will always receive a trivial response (because of the + * mismatch on the ). The trivial response will + * tell them our new 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 , their + * request of "builtin::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]; +} + +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). + * + * If there are no concurrent threads readering 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); +} + +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); +} + static ipc_server_application_cb handle_client; static int handle_client(void *data, @@ -316,6 +460,81 @@ enum fsmonitor_path_type fsmonitor_classify_path_absolute( 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); + } + } + + pthread_mutex_unlock(&state->main_lock); +} + static void *fsm_listen__thread_proc(void *_state) { struct fsmonitor_daemon_state *state = _state; @@ -330,6 +549,13 @@ static void *fsm_listen__thread_proc(void *_state) 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; } diff --git a/fsmonitor--daemon.h b/fsmonitor--daemon.h index 7bbb3a27a1c..20a815d80f8 100644 --- a/fsmonitor--daemon.h +++ b/fsmonitor--daemon.h @@ -12,6 +12,27 @@ struct fsmonitor_batch; struct fsmonitor_token_data; +/* + * Create a new batch of path(s). The returned batch is considered + * private and not linked into the fsmonitor daemon state. The caller + * should fill this batch with one or more paths and then publish it. + */ +struct fsmonitor_batch *fsmonitor_batch__new(void); + +/* + * Free the list of batches starting with this one. + */ +void fsmonitor_batch__free_list(struct fsmonitor_batch *batch); + +/* + * Add this path to this batch of modified files. + * + * The batch should be private and NOT (yet) linked into the fsmonitor + * daemon state and therefore not yet visible to worker threads and so + * no locking is required. + */ +void fsmonitor_batch__add_path(struct fsmonitor_batch *batch, const char *path); + struct fsmonitor_daemon_backend_data; /* opaque platform-specific data */ struct fsmonitor_daemon_state { @@ -91,5 +112,24 @@ enum fsmonitor_path_type fsmonitor_classify_path_absolute( struct fsmonitor_daemon_state *state, const char *path); +/* + * Prepend the this batch of path(s) onto the list of batches associated + * with the current token. This makes the batch visible to worker threads. + * + * The caller no longer owns the batch and must not free it. + * + * Wake up the client threads waiting on these cookies. + */ +void fsmonitor_publish(struct fsmonitor_daemon_state *state, + struct fsmonitor_batch *batch, + const struct string_list *cookie_names); + +/* + * If the platform-specific layer loses sync with the filesystem, + * it should call this to invalidate cached data and abort waiting + * threads. + */ +void fsmonitor_force_resync(struct fsmonitor_daemon_state *state); + #endif /* HAVE_FSMONITOR_DAEMON_BACKEND */ #endif /* FSMONITOR_DAEMON_H */