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Diffstat (limited to 'Documentation/git-fast-import.txt')
| -rw-r--r-- | Documentation/git-fast-import.txt | 92 |
1 files changed, 79 insertions, 13 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index 30ee98d17f..d5119678b5 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -176,6 +176,15 @@ results, such as branch names or file names with leading or trailing spaces in their name, or early termination of fast-import when it encounters unexpected input. +Stream Comments +~~~~~~~~~~~~~~~ +To aid in debugging frontends fast-import ignores any line that +begins with `#` (ASCII pound/hash) up to and including the line +ending `LF`. A comment line may contain any sequence of bytes +that does not contain an LF and therefore may be used to include +any detailed debugging information that might be specific to the +frontend and useful when inspecting a fast-import data stream. + Date Formats ~~~~~~~~~~~~ The following date formats are supported. A frontend should select @@ -232,7 +241,7 @@ been well tested in the wild. + 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`:: @@ -289,6 +298,11 @@ and control the current import process. More detailed discussion 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 @@ -303,7 +317,7 @@ change to the project. ('from' SP <committish> LF)? ('merge' SP <committish> LF)? (filemodify | filedelete | filecopy | filerename | filedeleteall)* - LF + LF? .... where `<ref>` is the name of the branch to make the commit on. @@ -329,11 +343,13 @@ Zero or more `filemodify`, `filedelete`, `filecopy`, `filerename` 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 `LF` after the command is optional (it used to be required). + `author` ^^^^^^^^ An `author` command may optionally appear, if the author information @@ -386,7 +402,7 @@ Here `<committish>` is any of the following: + 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. + @@ -471,7 +487,7 @@ 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"`. -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), @@ -645,12 +661,14 @@ branch from an existing commit without creating a new commit. .... 'reset' SP <ref> LF ('from' SP <committish> LF)? - LF + LF? .... For a detailed description of `<ref>` and `<committish>` see above under `commit` and `from`. +The `LF` after the command is optional (it used to be required). + The `reset` command can also be used to create lightweight (non-annotated) tags. For example: @@ -689,29 +707,40 @@ intended for production-quality conversions should always use the exact byte count format, as it is more robust and performs better. The delimited format is intended primarily for testing fast-import. +Comment lines appearing within the `<raw>` part of `data` commands +are always taken to be part of the body of the data and are therefore +never ignored by fast-import. This makes it safe to import any +file/message content whose lines might start with `#`. + Exact byte count format:: The frontend must specify the number of bytes of data. + .... 'data' SP <count> LF - <raw> LF + <raw> LF? .... + where `<count>` is the exact number of bytes appearing within `<raw>`. The value of `<count>` is expressed as an ASCII decimal integer. The `LF` on either side of `<raw>` is not included in `<count>` and will not be included in the imported data. ++ +The `LF` after `<raw>` is optional (it used to be required) but +recommended. Always including it makes debugging a fast-import +stream easier as the next command always starts in column 0 +of the next line, even if `<raw>` did not end with an `LF`. 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. + .... 'data' SP '<<' <delim> LF <raw> LF <delim> LF + LF? .... + where `<delim>` is the chosen delimiter string. The string `<delim>` @@ -720,6 +749,8 @@ fast-import will think the data ends earlier than it really does. The `LF` immediately trailing `<raw>` is part of `<raw>`. This is one of the limitations of the delimited format, it is impossible to supply a data chunk which does not have an LF as its last byte. ++ +The `LF` after `<delim> LF` is optional (it used to be required). `checkpoint` ~~~~~~~~~~~~ @@ -728,7 +759,7 @@ save out all current branch refs, tags and marks. .... 'checkpoint' LF - LF + LF? .... Note that fast-import automatically switches packfiles when the current @@ -747,6 +778,32 @@ process access to a branch. However given that a 30 GiB Subversion repository can be loaded into Git through fast-import in about 3 hours, explicit checkpointing may not be necessary. +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 --------------- @@ -816,7 +873,7 @@ to remove the dummy branch. 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 @@ -840,6 +897,15 @@ This will take longer, but will also produce a smaller packfile. 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 --------------------- @@ -876,8 +942,8 @@ Memory Utilization ------------------ 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 @@ -934,7 +1000,7 @@ per active tree ~~~~~~~~~~~~~~~ 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 |