From patchwork Sat May 22 13:56:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Hostetler X-Patchwork-Id: 12274579 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5847AC2B9F2 for ; Sat, 22 May 2021 13:57:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3186561164 for ; Sat, 22 May 2021 13:57:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231381AbhEVN7E (ORCPT ); Sat, 22 May 2021 09:59:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231252AbhEVN6r (ORCPT ); Sat, 22 May 2021 09:58:47 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F756C0613ED for ; Sat, 22 May 2021 06:57:21 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id q5so23718469wrs.4 for ; Sat, 22 May 2021 06:57:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=N5qY1y9CfNbyDb71UAUZBNInayWHSRyciKICzyYlGNc=; b=a7zIEy6p/mp+ncB6ECyifJ36s/YJC0+LOY7pwgFf3xm82nOUiFolImRqFMsV4bTDuJ lnzM2+lO0Y+W64nwajljg/+nbpz5vzZUqlQJ8quCnfCxMfhkLvLU2EDPuC7uucBOOr+P kdp6jq37scWOyuU3GjIXZXyUGKHtpABTaKAAaG8D1U43nlNAECXzL3CyXkFv4XpuZF6c Dqm1eZANuwyalDgwKwObRUXlWo/rEcQm1VUemOrVHl3msK29o22/TZ4eNK56+nD6/S+6 Tz0S7MIeZLGCmru2nNw/lDngix0o+sMOz6BOZ9z77dVc3NoXa+CUsTQ8OQY4Z2rO+wDy srhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=N5qY1y9CfNbyDb71UAUZBNInayWHSRyciKICzyYlGNc=; b=oKUUQnFho8UCeCHOfUW+n5Xkjyi4KRDnxP4xdsM6hMabyyGjrcfCNGcdqLzi+6RZS7 Jh4DdnCzHSMhkKyZTHn3FLAXUx/9e7K1l3ZV3iyU2h0RB4+NkkquV090a1ac25O0wcjr O0WyfPZanv86oBaCAdQnBYb89/2qatvGGErV22tx6pb0900OmMjaPLD9vooh3tpod82S PO8149saKpMeENTlwaqCi3pWVdBV0wXs0hRlGsMKWMP8FjgY9GFV8GONpC+NHUmbi1nc ZIofMZhBIU7KXlzT1Li29L/DrfuZK+1GLtgvCrN4uS8rnz1iRpq0i+MnztptRAjRP3wF Xd9Q== X-Gm-Message-State: AOAM531PW58YBzbqP/rG4VJyYNAqt0S3YyiTL8vhSJH52caCUcOmNVvL mBG18aQSCxGUiKjDjIqrKDC7zahhsX4= X-Google-Smtp-Source: ABdhPJys8ICuRvCxUDSGV0hmEv8wTEeLk0TBZWGD6gLiU2Yi+63WqTn+ro5e/dLhXKKLAe/XBSCd1Q== X-Received: by 2002:a5d:44cb:: with SMTP id z11mr14544923wrr.159.1621691840062; Sat, 22 May 2021 06:57:20 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id r1sm5420587wrt.67.2021.05.22.06.57.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 22 May 2021 06:57:19 -0700 (PDT) Message-Id: In-Reply-To: References: Date: Sat, 22 May 2021 13:56:54 +0000 Subject: [PATCH v2 15/28] fsmonitor--daemon: define token-ids Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Johannes Schindelin , Jeff Hostetler , Derrick Stolee , 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 create token-ids and define the overall token naming scheme. Signed-off-by: Jeff Hostetler --- builtin/fsmonitor--daemon.c | 116 +++++++++++++++++++++++++++++++++++- 1 file changed, 115 insertions(+), 1 deletion(-) diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c index d6e35ded9f68..ecd456dc9284 100644 --- a/builtin/fsmonitor--daemon.c +++ b/builtin/fsmonitor--daemon.c @@ -91,6 +91,120 @@ static int do_as_client__status(void) } } +/* + * 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" ":" ":" + * + * The "builtin" prefix is used as a namespace to avoid conflicts + * with other providers (such as Watchman). + * + * The 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 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 is created, the 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; +}; + +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; + + CALLOC_ARRAY(token, 1); + + strbuf_init(&token->token_id, 0); + token->batch_head = NULL; + token->batch_tail = NULL; + 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++); + } + + return token; +} + static ipc_server_application_cb handle_client; static int handle_client(void *data, @@ -281,7 +395,7 @@ static int fsmonitor_run_daemon(void) pthread_mutex_init(&state.main_lock, NULL); state.error_code = 0; - state.current_token_data = NULL; + state.current_token_data = fsmonitor_new_token_data(); /* Prepare to (recursively) watch the directory. */ strbuf_init(&state.path_worktree_watch, 0);