From 780494b1f5c3744860c485d1e9f1b23879f8936f Mon Sep 17 00:00:00 2001 From: Ben Peart Date: Fri, 22 Sep 2017 12:35:41 -0400 Subject: fsmonitor: add documentation for the fsmonitor extension. This includes the core.fsmonitor setting, the fsmonitor integration hook, and the fsmonitor index extension. Also add documentation for the new fsmonitor options to ls-files and update-index. Signed-off-by: Ben Peart Signed-off-by: Junio C Hamano diff --git a/Documentation/config.txt b/Documentation/config.txt index dc4e3f5..db52645 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -413,6 +413,13 @@ core.protectNTFS:: 8.3 "short" names. 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]. + core.trustctime:: If false, the ctime differences between the index and the working tree are ignored; useful when the inode change time diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt index d153c17..3ac3e3a 100644 --- a/Documentation/git-ls-files.txt +++ b/Documentation/git-ls-files.txt @@ -9,7 +9,7 @@ git-ls-files - Show information about files in the index and the working tree SYNOPSIS -------- [verse] -'git ls-files' [-z] [-t] [-v] +'git ls-files' [-z] [-t] [-v] [-f] (--[cached|deleted|others|ignored|stage|unmerged|killed|modified])* (-[c|d|o|i|s|u|k|m])* [--eol] @@ -133,6 +133,11 @@ a space) at the start of each line: that are marked as 'assume unchanged' (see linkgit:git-update-index[1]). +-f:: + Similar to `-t`, but use lowercase letters for files + that are marked as 'fsmonitor valid' (see + linkgit:git-update-index[1]). + --full-name:: When run from a subdirectory, the command usually outputs paths relative to the current directory. This diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt index e19eba6..7c2f880 100644 --- a/Documentation/git-update-index.txt +++ b/Documentation/git-update-index.txt @@ -16,9 +16,11 @@ SYNOPSIS [--chmod=(+|-)x] [--[no-]assume-unchanged] [--[no-]skip-worktree] + [--[no-]fsmonitor-valid] [--ignore-submodules] [--[no-]split-index] [--[no-|test-|force-]untracked-cache] + [--[no-]fsmonitor] [--really-refresh] [--unresolve] [--again | -g] [--info-only] [--index-info] [-z] [--stdin] [--index-version ] @@ -111,6 +113,12 @@ you will need to handle the situation manually. set and unset the "skip-worktree" bit for the paths. See section "Skip-worktree bit" below for more information. +--[no-]fsmonitor-valid:: + When one of these flags is specified, the object name recorded + for the paths are not updated. Instead, these options + set and unset the "fsmonitor valid" bit for the paths. See + section "File System Monitor" below for more information. + -g:: --again:: Runs 'git update-index' itself on the paths whose index @@ -201,6 +209,15 @@ will remove the intended effect of the option. `--untracked-cache` used to imply `--test-untracked-cache` but this option would enable the extension unconditionally. +--fsmonitor:: +--no-fsmonitor:: + Enable or disable files system monitor feature. These options + take effect whatever the value of the `core.fsmonitor` + configuration variable (see linkgit:git-config[1]). But a warning + is emitted when the change goes against the configured value, as + the configured value will take effect next time the index is + read and this will remove the intended effect of the option. + \--:: Do not interpret any more arguments as options. @@ -447,6 +464,34 @@ command reads the index; while when `--[no-|force-]untracked-cache` are used, the untracked cache is immediately added to or removed from the index. +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 +"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. + +When used in conjunction with the untracked cache, it can further improve +performance by avoiding the cost of scanning the entire working directory +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 +across all repositories you use, because you can set the configuration +variable to `true` (or `false`) in your `$HOME/.gitconfig` just once +and have it affect all repositories you touch. + +When the `core.fsmonitor` configuration variable is changed, the +file system monitor is added to or removed from the index the next time +a command reads the index. When `--[no-]fsmonitor` are used, the file +system monitor is immediately added to or removed from the index. + Configuration ------------- diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt index 1bb4f92..ae60559 100644 --- a/Documentation/githooks.txt +++ b/Documentation/githooks.txt @@ -455,6 +455,34 @@ the name of the file that holds the e-mail to be sent. Exiting with a non-zero status causes 'git send-email' to abort before sending any e-mails. +fsmonitor-watchman +~~~~~~~~~~~~~~~~~~ + +This hook is invoked when the configuration option core.fsmonitor is +set to .git/hooks/fsmonitor-watchman. It takes two arguments, a version +(currently 1) and the time in elapsed nanoseconds since midnight, +January 1, 1970. + +The hook should output to stdout the list of all files in the working +directory that may have changed since the requested time. The logic +should be inclusive so that it does not miss any potential changes. +The paths should be relative to the root of the working directory +and be separated by a single NUL. + +It is OK to include files which have not actually changed. All changes +including newly-created and deleted files should be included. When +files are renamed, both the old and the new name should be included. + +Git will limit what files it checks for changes as well as which +directories are checked for untracked files based on the path names +given. + +An optimized way to tell git "all files have changed" is to return +the filename '/'. + +The exit status determines whether git will use the data from the +hook to limit its search. On error, it will fall back to verifying +all files and folders. GIT --- diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt index ade0b0c..db35726 100644 --- a/Documentation/technical/index-format.txt +++ b/Documentation/technical/index-format.txt @@ -295,3 +295,22 @@ The remaining data of each directory block is grouped by type: in the previous ewah bitmap. - One NUL. + +== File System Monitor cache + + The file system monitor cache tracks files for which the core.fsmonitor + hook has told us about changes. The signature for this extension is + { 'F', 'S', 'M', 'N' }. + + The extension starts with + + - 32-bit version number: the current supported version is 1. + + - 64-bit time: the extension data reflects all changes through the given + time which is stored as the nanoseconds elapsed since midnight, + January 1, 1970. + + - 32-bit bitmap size: the size of the CE_FSMONITOR_VALID bitmap. + + - An ewah bitmap, the n-th bit indicates whether the n-th index entry + is not CE_FSMONITOR_VALID. -- cgit v0.10.2-6-g49f6