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Diffstat (limited to 'Documentation/git-fast-import.txt')
| -rw-r--r-- | Documentation/git-fast-import.txt | 159 |
1 files changed, 106 insertions, 53 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index ec6ef31197..bf1a02a80d 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -33,34 +33,46 @@ the frontend program in use. OPTIONS ------- ---date-format=<fmt>:: - Specify the type of dates the frontend will supply to - fast-import within `author`, `committer` and `tagger` commands. - See ``Date Formats'' below for details about which formats - are supported, and their syntax. --force:: Force updating modified existing branches, even if doing so would cause commits to be lost (as the new commit does not contain the old commit). ---max-pack-size=<n>:: - Maximum size of each output packfile. - The default is unlimited. +--quiet:: + Disable all non-fatal output, making fast-import silent when it + is successful. This option disables the output shown by + \--stats. ---big-file-threshold=<n>:: - Maximum size of a blob that fast-import will attempt to - create a delta for, expressed in bytes. The default is 512m - (512 MiB). Some importers may wish to lower this on systems - with constrained memory. +--stats:: + Display some basic statistics about the objects fast-import has + created, the packfiles they were stored into, and the + memory used by fast-import during this run. Showing this output + is currently the default, but can be disabled with \--quiet. ---depth=<n>:: - Maximum delta depth, for blob and tree deltification. - Default is 10. +Options for Frontends +~~~~~~~~~~~~~~~~~~~~~ ---active-branches=<n>:: - Maximum number of branches to maintain active at once. - See ``Memory Utilization'' below for details. Default is 5. +--cat-blob-fd=<fd>:: + Write responses to `cat-blob` and `ls` queries to the + file descriptor <fd> instead of `stdout`. Allows `progress` + output intended for the end-user to be separated from other + output. + +--date-format=<fmt>:: + Specify the type of dates the frontend will supply to + fast-import within `author`, `committer` and `tagger` commands. + See ``Date Formats'' below for details about which formats + are supported, and their syntax. + +--done:: + Terminate with error if there is no `done` command at the end of + the stream. This option might be useful for detecting errors + that cause the frontend to terminate before it has started to + write a stream. + +Locations of Marks Files +~~~~~~~~~~~~~~~~~~~~~~~~ --export-marks=<file>:: Dumps the internal marks table to <file> when complete. @@ -83,30 +95,33 @@ OPTIONS Like --import-marks but instead of erroring out, silently skips the file if it does not exist. ---relative-marks:: +--[no-]relative-marks:: After specifying --relative-marks the paths specified with --import-marks= and --export-marks= are relative to an internal directory in the current repository. In git-fast-import this means that the paths are relative to the .git/info/fast-import directory. However, other importers may use a different location. ++ +Relative and non-relative marks may be combined by interweaving +--(no-)-relative-marks with the --(import|export)-marks= options. ---no-relative-marks:: - Negates a previous --relative-marks. Allows for combining - relative and non-relative marks by interweaving - --(no-)-relative-marks with the --(import|export)-marks= - options. +Performance and Compression Tuning +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ---cat-blob-fd=<fd>:: - Specify the file descriptor that will be written to - when the `cat-blob` command is encountered in the stream. - The default behaviour is to write to `stdout`. +--active-branches=<n>:: + Maximum number of branches to maintain active at once. + See ``Memory Utilization'' below for details. Default is 5. ---done:: - Require a `done` command at the end of the stream. - This option might be useful for detecting errors that - cause the frontend to terminate before it has started to - write a stream. +--big-file-threshold=<n>:: + Maximum size of a blob that fast-import will attempt to + create a delta for, expressed in bytes. The default is 512m + (512 MiB). Some importers may wish to lower this on systems + with constrained memory. + +--depth=<n>:: + Maximum delta depth, for blob and tree deltification. + Default is 10. --export-pack-edges=<file>:: After creating a packfile, print a line of data to @@ -117,16 +132,9 @@ OPTIONS as these commits can be used as edge points during calls to 'git pack-objects'. ---quiet:: - Disable all non-fatal output, making fast-import silent when it - is successful. This option disables the output shown by - \--stats. - ---stats:: - Display some basic statistics about the objects fast-import has - created, the packfiles they were stored into, and the - memory used by fast-import during this run. Showing this output - is currently the default, but can be disabled with \--quiet. +--max-pack-size=<n>:: + Maximum size of each output packfile. + The default is unlimited. Performance @@ -422,7 +430,7 @@ they made it. Here `<name>` is the person's display name (for example ``Com M Itter'') and `<email>` is the person's email address -(``cm@example.com''). `LT` and `GT` are the literal less-than (\x3c) +(``\cm@example.com''). `LT` and `GT` are the literal less-than (\x3c) and greater-than (\x3e) symbols. These are required to delimit the email address from the other fields in the line. Note that `<name>` and `<email>` are free-form and may contain any sequence @@ -437,7 +445,9 @@ their syntax. ^^^^^^ The `from` command is used to specify the commit to initialize this branch from. This revision will be the first ancestor of the -new commit. +new commit. The state of the tree built at this commit will begin +with the state at the `from` commit, and be altered by the content +modifications in this commit. Omitting the `from` command in the first commit of a new branch will cause fast-import to create that commit with no ancestor. This @@ -478,16 +488,18 @@ current branch value should be written as: ---- from refs/heads/branch^0 ---- -The `{caret}0` suffix is necessary as fast-import does not permit a branch to +The `^0` suffix is necessary as fast-import does not permit a branch to start from itself, and the branch is created in memory before the -`from` command is even read from the input. Adding `{caret}0` will force +`from` command is even read from the input. Adding `^0` will force fast-import to resolve the commit through Git's revision parsing library, rather than its internal branch table, thereby loading in the existing value of the branch. `merge` ^^^^^^^ -Includes one additional ancestor commit. If the `from` command is +Includes one additional ancestor commit. The additional ancestry +link does not change the way the tree state is built at this commit. +If the `from` command is omitted when creating a new branch, the first `merge` commit will be the first ancestor of the current commit, and the branch will start out with no files. An unlimited number of `merge` commands per @@ -553,8 +565,12 @@ A `<path>` string must use UNIX-style directory separators (forward slash `/`), may contain any byte other than `LF`, and must not start with double quote (`"`). -If an `LF` or double quote must be encoded into `<path>` shell-style -quoting should be used, e.g. `"path/with\n and \" in it"`. +A path can use C-style string quoting; this is accepted in all cases +and mandatory if the filename starts with double quote or contains +`LF`. In C-style quoting, the complete name should be surrounded with +double quotes, and any `LF`, backslash, or double quote characters +must be escaped by preceding them with a backslash (e.g., +`"path/with\n, \\ and \" in it"`). The value of `<path>` must be in canonical form. That is it must not: @@ -942,6 +958,9 @@ This command can be used anywhere in the stream that comments are accepted. In particular, the `cat-blob` command can be used in the middle of a commit but not in the middle of a `data` command. +See ``Responses To Commands'' below for details about how to read +this output safely. + `ls` ~~~~ Prints information about the object at a path to a file descriptor @@ -975,7 +994,7 @@ Reading from a named tree:: See `filemodify` above for a detailed description of `<path>`. -Output uses the same format as `git ls-tree <tree> {litdd} <path>`: +Output uses the same format as `git ls-tree <tree> -- <path>`: ==== <mode> SP ('blob' | 'tree' | 'commit') SP <dataref> HT <path> LF @@ -991,6 +1010,9 @@ instead report missing SP <path> LF ==== +See ``Responses To Commands'' below for details about how to read +this output safely. + `feature` ~~~~~~~~~ Require that fast-import supports the specified feature, or abort if @@ -1040,7 +1062,9 @@ done:: Error out if the stream ends without a 'done' command. Without this feature, errors causing the frontend to end abruptly at a convenient point in the stream can go - undetected. + undetected. This may occur, for example, if an import + front end dies in mid-operation without emitting SIGTERM + or SIGKILL at its subordinate git fast-import instance. `option` ~~~~~~~~ @@ -1079,6 +1103,35 @@ If the `--done` command line option or `feature done` command is in use, the `done` command is mandatory and marks the end of the stream. +Responses To Commands +--------------------- +New objects written by fast-import are not available immediately. +Most fast-import commands have no visible effect until the next +checkpoint (or completion). The frontend can send commands to +fill fast-import's input pipe without worrying about how quickly +they will take effect, which improves performance by simplifying +scheduling. + +For some frontends, though, it is useful to be able to read back +data from the current repository as it is being updated (for +example when the source material describes objects in terms of +patches to be applied to previously imported objects). This can +be accomplished by connecting the frontend and fast-import via +bidirectional pipes: + +==== + mkfifo fast-import-output + frontend <fast-import-output | + git fast-import >fast-import-output +==== + +A frontend set up this way can use `progress`, `ls`, and `cat-blob` +commands to read information from the import in progress. + +To avoid deadlock, such frontends must completely consume any +pending output from `progress`, `ls`, and `cat-blob` before +performing writes to fast-import that might block. + Crash Reports ------------- If fast-import is supplied invalid input it will terminate with a |