From patchwork Fri Mar 25 18:02:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Hostetler X-Patchwork-Id: 12792007 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 25112C433EF for ; Fri, 25 Mar 2022 19:43:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231547AbiCYTpc (ORCPT ); Fri, 25 Mar 2022 15:45:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231584AbiCYTot (ORCPT ); Fri, 25 Mar 2022 15:44:49 -0400 Received: from mail-wm1-x334.google.com (mail-wm1-x334.google.com [IPv6:2a00:1450:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A20336BA2C for ; Fri, 25 Mar 2022 12:16:09 -0700 (PDT) Received: by mail-wm1-x334.google.com with SMTP id 123-20020a1c1981000000b0038b3616a71aso4948669wmz.4 for ; Fri, 25 Mar 2022 12:16:09 -0700 (PDT) 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=C/9cpq+/7LFgJqbFs52lTGJrXKzcUu9HQhf3f89AGVk=; b=oqt2QaZKUjP8BWVNQfzKsGQB9qjqOA2aEBZxKy/HULh9LiocsHQ9+I6yI7Qsdi2ykw 4CraPXPioY7yFZzZYTxPakHOYlJF9U+LdStup5FLRjDfBtJnDONH65ovwjtt3NCstHz9 dxlf6zz1wrdWBWOIzZie0Z5K5A8Vm3I7h43LRXoCreymDhcn0qS3N0BsH8UVgRUNG/z3 71CVQS6Tge1NHOLBDQWxZ9BsvGTiwbjkbxua8zbbI7D8+0SkJwPoO7M3t8fl5FMGsY/Z 6Vumlga7BLXreEpYiYs0fqYk7GFe4GbPkgYWXRbwR8AVIvMKuC0nx7scYk+hBD9Yxert iiow== 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=C/9cpq+/7LFgJqbFs52lTGJrXKzcUu9HQhf3f89AGVk=; b=II0JmW2briqkDps653bUnTCPG5+9JJhq3AJVs3tQD3LB6mr7OwJvGUQdr4H3HxavRQ xldE3t3LbK3p5/PdUHV4apPxojczMcBW4atO8rQKETeY/FMYAY6BbMiU3WAGGAgt7QJl luR73WS+qRZDIp2tc4Wo7xzmSMnz41Wd71Bo+IyMXm/l0ja4vPTa+ib25e+uBABrbDXl zs6pP1g5Ggbq10sUCGu7TyGbSWZiAwjZPMslZrVBvv4Y7FnqBNweTvAgwAVy8QsUX6u+ jBL4lEoLJ7stUfMdvDGvElsc/WcPDxmQFq/L2WGaQoW57vuDnrwwbhxaxFwlzZjeNSGy zO7A== X-Gm-Message-State: AOAM533H00i4jlU4OPM3gwT0VeudeXD3p8p6pbG3/iIL1q3nYr301KOm Xf6lXAXWhetC8UqPLxh34hM3PXvdYxU= X-Google-Smtp-Source: ABdhPJzWWol4t2smtV4PP6qduFWnFN94k9fYYh4Dfs600SdRiXmhA1Si82X/JMHZfsvh2HI5kmPeWw== X-Received: by 2002:a7b:ce83:0:b0:37b:f1f1:3a0c with SMTP id q3-20020a7bce83000000b0037bf1f13a0cmr11156411wmj.10.1648231400682; Fri, 25 Mar 2022 11:03:20 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id n8-20020adf8b08000000b001f046cc8891sm5729259wra.24.2022.03.25.11.03.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Mar 2022 11:03:20 -0700 (PDT) Message-Id: <6ab7db9cb769fe44db2c76e82da0b5d898538ec0.1648231393.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Fri, 25 Mar 2022 18:02:48 +0000 Subject: [PATCH v9 05/30] fsmonitor: document builtin fsmonitor Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Bagas Sanjaya , =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason , Jeff Hostetler , Eric Sunshine , Johannes Schindelin , Tao Klerks , rsbecker@nexbridge.com, Jeff Hostetler , Jeff Hostetler Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Jeff Hostetler From: Jeff Hostetler Document how `core.fsmonitor` can be set to a boolean to enable or disable the builtin FSMonitor. Update references to `core.fsmonitor` and `core.fsmonitorHookVersion` and pointers to `Watchman` to refer to it. Create `git-fsmonitor--daemon` manual page and describe its features. Signed-off-by: Jeff Hostetler Signed-off-by: Junio C Hamano --- Documentation/config/core.txt | 60 +++++++++++++++----- Documentation/git-fsmonitor--daemon.txt | 75 +++++++++++++++++++++++++ Documentation/git-update-index.txt | 8 ++- 3 files changed, 126 insertions(+), 17 deletions(-) create mode 100644 Documentation/git-fsmonitor--daemon.txt diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt index c04f62a54a1..6303c36c7ed 100644 --- a/Documentation/config/core.txt +++ b/Documentation/config/core.txt @@ -62,22 +62,54 @@ core.protectNTFS:: Defaults to `true` on Windows, and `false` elsewhere. core.fsmonitor:: - If set, the value of this variable is used as a command which - will identify all files that may have changed since the - requested date/time. This information is used to speed up git by - avoiding unnecessary processing of files that have not changed. - See the "fsmonitor-watchman" section of linkgit:githooks[5]. + If set to true, enable the built-in file system monitor + daemon for this working directory (linkgit:git-fsmonitor--daemon[1]). ++ +Like hook-based file system monitors, the built-in file system monitor +can speed up Git commands that need to refresh the Git index +(e.g. `git status`) in a working directory with many files. The +built-in monitor eliminates the need to install and maintain an +external third-party tool. ++ +The built-in file system monitor is currently available only on a +limited set of supported platforms. Currently, this includes Windows +and MacOS. ++ + Otherwise, this variable contains the pathname of the "fsmonitor" + hook command. ++ +This hook command is used to identify all files that may have changed +since the requested date/time. This information is used to speed up +git by avoiding unnecessary scanning of files that have not changed. ++ +See the "fsmonitor-watchman" section of linkgit:githooks[5]. ++ +Note that if you concurrently use multiple versions of Git, such +as one version on the command line and another version in an IDE +tool, that the definition of `core.fsmonitor` was extended to +allow boolean values in addition to hook pathnames. Git versions +2.35.1 and prior will not understand the boolean values and will +consider the "true" or "false" values as hook pathnames to be +invoked. Git versions 2.26 thru 2.35.1 default to hook protocol +V2 and will fall back to no fsmonitor (full scan). Git versions +prior to 2.26 default to hook protocol V1 and will silently +assume there were no changes to report (no scan), so status +commands may report incomplete results. For this reason, it is +best to upgrade all of your Git versions before using the built-in +file system monitor. core.fsmonitorHookVersion:: - Sets the version of hook that is to be used when calling fsmonitor. - There are currently versions 1 and 2. When this is not set, - version 2 will be tried first and if it fails then version 1 - will be tried. Version 1 uses a timestamp as input to determine - which files have changes since that time but some monitors - like watchman have race conditions when used with a timestamp. - Version 2 uses an opaque string so that the monitor can return - something that can be used to determine what files have changed - without race conditions. + Sets the protocol version to be used when invoking the + "fsmonitor" hook. ++ +There are currently versions 1 and 2. When this is not set, +version 2 will be tried first and if it fails then version 1 +will be tried. Version 1 uses a timestamp as input to determine +which files have changes since that time but some monitors +like Watchman have race conditions when used with a timestamp. +Version 2 uses an opaque string so that the monitor can return +something that can be used to determine what files have changed +without race conditions. core.trustctime:: If false, the ctime differences between the index and the diff --git a/Documentation/git-fsmonitor--daemon.txt b/Documentation/git-fsmonitor--daemon.txt new file mode 100644 index 00000000000..0fedf5a4565 --- /dev/null +++ b/Documentation/git-fsmonitor--daemon.txt @@ -0,0 +1,75 @@ +git-fsmonitor--daemon(1) +======================== + +NAME +---- +git-fsmonitor--daemon - A Built-in File System Monitor + +SYNOPSIS +-------- +[verse] +'git fsmonitor--daemon' start +'git fsmonitor--daemon' run +'git fsmonitor--daemon' stop +'git fsmonitor--daemon' status + +DESCRIPTION +----------- + +A daemon to watch the working directory for file and directory +changes using platform-specific file system notification facilities. + +This daemon communicates directly with commands like `git status` +using the link:technical/api-simple-ipc.html[simple IPC] interface +instead of the slower linkgit:githooks[5] interface. + +This daemon is built into Git so that no third-party tools are +required. + +OPTIONS +------- + +start:: + Starts a daemon in the background. + +run:: + Runs a daemon in the foreground. + +stop:: + Stops the daemon running in the current working + directory, if present. + +status:: + Exits with zero status if a daemon is watching the + current working directory. + +REMARKS +------- + +This daemon is a long running process used to watch a single working +directory and maintain a list of the recently changed files and +directories. Performance of commands such as `git status` can be +increased if they just ask for a summary of changes to the working +directory and can avoid scanning the disk. + +When `core.fsmonitor` is set to `true` (see linkgit:git-config[1]) +commands, such as `git status`, will ask the daemon for changes and +automatically start it (if necessary). + +For more information see the "File System Monitor" section in +linkgit:git-update-index[1]. + +CAVEATS +------- + +The fsmonitor daemon does not currently know about submodules and does +not know to filter out file system events that happen within a +submodule. If fsmonitor daemon is watching a super repo and a file is +modified within the working directory of a submodule, it will report +the change (as happening against the super repo). However, the client +will properly ignore these extra events, so performance may be affected +but it will not cause an incorrect result. + +GIT +--- +Part of the linkgit:git[1] suite diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt index 2853f168d97..53ea48a04e2 100644 --- a/Documentation/git-update-index.txt +++ b/Documentation/git-update-index.txt @@ -498,7 +498,9 @@ FILE SYSTEM MONITOR This feature is intended to speed up git operations for repos that have large working directories. -It enables git to work together with a file system monitor (see the +It enables git to work together with a file system monitor (see +linkgit:git-fsmonitor--daemon[1] +and the "fsmonitor-watchman" section of linkgit:githooks[5]) that can inform it as to what files have been modified. This enables git to avoid having to lstat() every file to find modified files. @@ -509,8 +511,8 @@ looking for new files. If you want to enable (or disable) this feature, it is easier to use the `core.fsmonitor` configuration variable (see -linkgit:git-config[1]) than using the `--fsmonitor` option to -`git update-index` in each repository, especially if you want to do so +linkgit:git-config[1]) than using the `--fsmonitor` option to `git +update-index` in each repository, especially if you want to do so across all repositories you use, because you can set the configuration variable in your `$HOME/.gitconfig` just once and have it affect all repositories you touch.