76d7602631
Git uses zlib for its own object store, but calls gzip when creating tgz
archives. Add an option to perform the gzip compression for the latter
using zlib, without depending on the external gzip binary.
Plug it in by making write_block a function pointer and switching to a
compressing variant if the filter command has the magic value "git
archive gzip". Does that indirection slow down tar creation? Not
really, at least not in this test:
$ hyperfine -w3 -L rev HEAD,origin/main -p 'git checkout {rev} && make' \
'./git -C ../linux archive --format=tar HEAD # {rev}'
Benchmark #1: ./git -C ../linux archive --format=tar HEAD # HEAD
Time (mean ± σ): 4.044 s ± 0.007 s [User: 3.901 s, System: 0.137 s]
Range (min … max): 4.038 s … 4.059 s 10 runs
Benchmark #2: ./git -C ../linux archive --format=tar HEAD # origin/main
Time (mean ± σ): 4.047 s ± 0.009 s [User: 3.903 s, System: 0.138 s]
Range (min … max): 4.038 s … 4.066 s 10 runs
How does tgz creation perform?
$ hyperfine -w3 -L command 'gzip -cn','git archive gzip' \
'./git -c tar.tgz.command="{command}" -C ../linux archive --format=tgz HEAD'
Benchmark #1: ./git -c tar.tgz.command="gzip -cn" -C ../linux archive --format=tgz HEAD
Time (mean ± σ): 20.404 s ± 0.006 s [User: 23.943 s, System: 0.401 s]
Range (min … max): 20.395 s … 20.414 s 10 runs
Benchmark #2: ./git -c tar.tgz.command="git archive gzip" -C ../linux archive --format=tgz HEAD
Time (mean ± σ): 23.807 s ± 0.023 s [User: 23.655 s, System: 0.145 s]
Range (min … max): 23.782 s … 23.857 s 10 runs
Summary
'./git -c tar.tgz.command="gzip -cn" -C ../linux archive --format=tgz HEAD' ran
1.17 ± 0.00 times faster than './git -c tar.tgz.command="git archive gzip" -C ../linux archive --format=tgz HEAD'
So the internal implementation takes 17% longer on the Linux repo, but
uses 2% less CPU time. That's because the external gzip can run in
parallel on its own processor, while the internal one works sequentially
and avoids the inter-process communication overhead.
What are the benefits? Only an internal sequential implementation can
offer this eco mode, and it allows avoiding the gzip(1) requirement.
This implementation uses the helper functions from our zlib.c instead of
the convenient gz* functions from zlib, because the latter doesn't give
the control over the generated gzip header that the next patch requires.
Original-patch-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
237 lines
8.1 KiB
Plaintext
237 lines
8.1 KiB
Plaintext
git-archive(1)
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==============
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NAME
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----
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git-archive - Create an archive of files from a named tree
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SYNOPSIS
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--------
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[verse]
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'git archive' [--format=<fmt>] [--list] [--prefix=<prefix>/] [<extra>]
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[-o <file> | --output=<file>] [--worktree-attributes]
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[--remote=<repo> [--exec=<git-upload-archive>]] <tree-ish>
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[<path>...]
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DESCRIPTION
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-----------
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Creates an archive of the specified format containing the tree
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structure for the named tree, and writes it out to the standard
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output. If <prefix> is specified it is
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prepended to the filenames in the archive.
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'git archive' behaves differently when given a tree ID versus when
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given a commit ID or tag ID. In the first case the current time is
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used as the modification time of each file in the archive. In the latter
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case the commit time as recorded in the referenced commit object is
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used instead. Additionally the commit ID is stored in a global
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extended pax header if the tar format is used; it can be extracted
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using 'git get-tar-commit-id'. In ZIP files it is stored as a file
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comment.
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OPTIONS
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-------
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--format=<fmt>::
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Format of the resulting archive. Possible values are `tar`,
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`zip`, `tar.gz`, `tgz`, and any format defined using the
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configuration option `tar.<format>.command`. If `--format`
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is not given, and the output file is specified, the format is
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inferred from the filename if possible (e.g. writing to `foo.zip`
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makes the output to be in the `zip` format). Otherwise the output
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format is `tar`.
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-l::
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--list::
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Show all available formats.
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-v::
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--verbose::
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Report progress to stderr.
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--prefix=<prefix>/::
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Prepend <prefix>/ to paths in the archive. Can be repeated; its
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rightmost value is used for all tracked files. See below which
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value gets used by `--add-file` and `--add-virtual-file`.
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-o <file>::
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--output=<file>::
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Write the archive to <file> instead of stdout.
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--add-file=<file>::
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Add a non-tracked file to the archive. Can be repeated to add
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multiple files. The path of the file in the archive is built by
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concatenating the value of the last `--prefix` option (if any)
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before this `--add-file` and the basename of <file>.
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--add-virtual-file=<path>:<content>::
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Add the specified contents to the archive. Can be repeated to add
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multiple files. The path of the file in the archive is built
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by concatenating the value of the last `--prefix` option (if any)
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before this `--add-virtual-file` and `<path>`.
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+
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The `<path>` argument can start and end with a literal double-quote
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character; the contained file name is interpreted as a C-style string,
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i.e. the backslash is interpreted as escape character. The path must
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be quoted if it contains a colon, to avoid the colon from being
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misinterpreted as the separator between the path and the contents, or
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if the path begins or ends with a double-quote character.
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+
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The file mode is limited to a regular file, and the option may be
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subject to platform-dependent command-line limits. For non-trivial
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cases, write an untracked file and use `--add-file` instead.
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--worktree-attributes::
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Look for attributes in .gitattributes files in the working tree
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as well (see <<ATTRIBUTES>>).
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<extra>::
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This can be any options that the archiver backend understands.
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See next section.
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--remote=<repo>::
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Instead of making a tar archive from the local repository,
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retrieve a tar archive from a remote repository. Note that the
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remote repository may place restrictions on which sha1
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expressions may be allowed in `<tree-ish>`. See
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linkgit:git-upload-archive[1] for details.
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--exec=<git-upload-archive>::
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Used with --remote to specify the path to the
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'git-upload-archive' on the remote side.
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<tree-ish>::
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The tree or commit to produce an archive for.
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<path>::
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Without an optional path parameter, all files and subdirectories
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of the current working directory are included in the archive.
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If one or more paths are specified, only these are included.
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BACKEND EXTRA OPTIONS
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---------------------
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zip
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~~~
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-<digit>::
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Specify compression level. Larger values allow the command
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to spend more time to compress to smaller size. Supported
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values are from `-0` (store-only) to `-9` (best ratio).
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Default is `-6` if not given.
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tar
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~~~
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-<number>::
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Specify compression level. The value will be passed to the
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compression command configured in `tar.<format>.command`. See
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manual page of the configured command for the list of supported
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levels and the default level if this option isn't specified.
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CONFIGURATION
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-------------
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tar.umask::
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This variable can be used to restrict the permission bits of
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tar archive entries. The default is 0002, which turns off the
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world write bit. The special value "user" indicates that the
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archiving user's umask will be used instead. See umask(2) for
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details. If `--remote` is used then only the configuration of
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the remote repository takes effect.
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tar.<format>.command::
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This variable specifies a shell command through which the tar
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output generated by `git archive` should be piped. The command
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is executed using the shell with the generated tar file on its
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standard input, and should produce the final output on its
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standard output. Any compression-level options will be passed
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to the command (e.g., `-9`).
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+
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The `tar.gz` and `tgz` formats are defined automatically and use the
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command `gzip -cn` by default. An internal gzip implementation can be
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used by specifying the value `git archive gzip`.
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tar.<format>.remote::
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If true, enable the format for use by remote clients via
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linkgit:git-upload-archive[1]. Defaults to false for
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user-defined formats, but true for the `tar.gz` and `tgz`
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formats.
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[[ATTRIBUTES]]
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ATTRIBUTES
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----------
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export-ignore::
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Files and directories with the attribute export-ignore won't be
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added to archive files. See linkgit:gitattributes[5] for details.
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export-subst::
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If the attribute export-subst is set for a file then Git will
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expand several placeholders when adding this file to an archive.
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See linkgit:gitattributes[5] for details.
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Note that attributes are by default taken from the `.gitattributes` files
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in the tree that is being archived. If you want to tweak the way the
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output is generated after the fact (e.g. you committed without adding an
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appropriate export-ignore in its `.gitattributes`), adjust the checked out
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`.gitattributes` file as necessary and use `--worktree-attributes`
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option. Alternatively you can keep necessary attributes that should apply
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while archiving any tree in your `$GIT_DIR/info/attributes` file.
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EXAMPLES
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--------
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`git archive --format=tar --prefix=junk/ HEAD | (cd /var/tmp/ && tar xf -)`::
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Create a tar archive that contains the contents of the
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latest commit on the current branch, and extract it in the
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`/var/tmp/junk` directory.
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`git archive --format=tar --prefix=git-1.4.0/ v1.4.0 | gzip >git-1.4.0.tar.gz`::
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Create a compressed tarball for v1.4.0 release.
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`git archive --format=tar.gz --prefix=git-1.4.0/ v1.4.0 >git-1.4.0.tar.gz`::
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Same as above, but using the builtin tar.gz handling.
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`git archive --prefix=git-1.4.0/ -o git-1.4.0.tar.gz v1.4.0`::
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Same as above, but the format is inferred from the output file.
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`git archive --format=tar --prefix=git-1.4.0/ v1.4.0^{tree} | gzip >git-1.4.0.tar.gz`::
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Create a compressed tarball for v1.4.0 release, but without a
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global extended pax header.
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`git archive --format=zip --prefix=git-docs/ HEAD:Documentation/ > git-1.4.0-docs.zip`::
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Put everything in the current head's Documentation/ directory
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into 'git-1.4.0-docs.zip', with the prefix 'git-docs/'.
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`git archive -o latest.zip HEAD`::
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Create a Zip archive that contains the contents of the latest
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commit on the current branch. Note that the output format is
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inferred by the extension of the output file.
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`git archive -o latest.tar --prefix=build/ --add-file=configure --prefix= HEAD`::
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Creates a tar archive that contains the contents of the latest
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commit on the current branch with no prefix and the untracked
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file 'configure' with the prefix 'build/'.
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`git config tar.tar.xz.command "xz -c"`::
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Configure a "tar.xz" format for making LZMA-compressed tarfiles.
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You can use it specifying `--format=tar.xz`, or by creating an
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output file like `-o foo.tar.xz`.
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SEE ALSO
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--------
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linkgit:gitattributes[5]
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GIT
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---
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Part of the linkgit:git[1] suite
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