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index 1644b90ceafb3ca968f3fea3036e135cf17280d6..d5119678b59492db4651006391fd693a1a12601a 100644 (file)
+
Frontends should prefer the `raw` format if the source material
already uses UNIX-epoch format, can be coaxed to give dates in that
-format, or its format is easiliy convertible to it, as there is no
+format, or its format is easily convertible to it, as there is no
ambiguity in parsing.
`now`::
This command is optional and is not needed to perform
an import.
+`progress`::
+ Causes fast-import to echo the entire line to its own
+ standard output. This command is optional and is not needed
+ to perform an import.
+
`commit`
~~~~~~~~
Create or update a branch with a new commit, recording one logical
and `filedeleteall` commands
may be included to update the contents of the branch prior to
creating the commit. These commands may be supplied in any order.
-However it is recommended that a `filedeleteall` command preceed
+However it is recommended that a `filedeleteall` command precede
all `filemodify`, `filecopy` and `filerename` commands in the same
commit, as `filedeleteall`
wipes the branch clean (see below).
+
The reason fast-import uses `:` to denote a mark reference is this character
is not legal in a Git branch name. The leading `:` makes it easy
-to distingush between the mark 42 (`:42`) and the branch 42 (`42`
+to distinguish between the mark 42 (`:42`) and the branch 42 (`42`
or `refs/heads/42`), or an abbreviated SHA-1 which happened to
consist only of base-10 digits.
+
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"`.
-The value of `<path>` must be in canoncial form. That is it must not:
+The value of `<path>` must be in canonical form. That is it must not:
* contain an empty directory component (e.g. `foo//bar` is invalid),
* end with a directory separator (e.g. `foo/` is invalid),
Delimited format::
A delimiter string is used to mark the end of the data.
fast-import will compute the length by searching for the delimiter.
- This format is primarly useful for testing and is not
+ This format is primarily useful for testing and is not
recommended for real data.
+
....
The `LF` after the command is optional (it used to be required).
+`progress`
+~~~~~~~~~~
+Causes fast-import to print the entire `progress` line unmodified to
+its standard output channel (file descriptor 1) when the command is
+processed from the input stream. The command otherwise has no impact
+on the current import, or on any of fast-import's internal state.
+
+....
+ 'progress' SP <any> LF
+ LF?
+....
+
+The `<any>` part of the command may contain any sequence of bytes
+that does not contain `LF`. The `LF` after the command is optional.
+Callers may wish to process the output through a tool such as sed to
+remove the leading part of the line, for example:
+
+====
+ frontend | git-fast-import | sed 's/^progress //'
+====
+
+Placing a `progress` command immediately after a `checkpoint` will
+inform the reader when the `checkpoint` has been completed and it
+can safely access the refs that fast-import updated.
+
Tips and Tricks
---------------
The following tips and tricks have been collected from various
Import Now, Repack Later
~~~~~~~~~~~~~~~~~~~~~~~~
As soon as fast-import completes the Git repository is completely valid
-and ready for use. Typicallly this takes only a very short time,
+and ready for use. Typically this takes only a very short time,
even for considerably large projects (100,000+ commits).
However repacking the repository is necessary to improve data
You only need to expend the effort once, and everyone using your
project will benefit from the smaller repository.
+Include Some Progress Messages
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Every once in a while have your frontend emit a `progress` message
+to fast-import. The contents of the messages are entirely free-form,
+so one suggestion would be to output the current month and year
+each time the current commit date moves into the next month.
+Your users will feel better knowing how much of the data stream
+has been processed.
+
Packfile Optimization
---------------------
------------------
There are a number of factors which affect how much memory fast-import
requires to perform an import. Like critical sections of core
-Git, fast-import uses its own memory allocators to ammortize any overheads
-associated with malloc. In practice fast-import tends to ammoritize any
+Git, fast-import uses its own memory allocators to amortize any overheads
+associated with malloc. In practice fast-import tends to amortize any
malloc overheads to 0, due to its use of large block allocations.
per object
~~~~~~~~~~~~~~~
Trees (aka directories) use just 12 bytes of memory on top of the
memory required for their entries (see ``per active file'' below).
-The cost of a tree is virtually 0, as its overhead ammortizes out
+The cost of a tree is virtually 0, as its overhead amortizes out
over the individual file entries.
per active file entry