diff options
Diffstat (limited to 'Documentation/git-fast-import.txt')
| -rw-r--r-- | Documentation/git-fast-import.txt | 48 |
1 files changed, 42 insertions, 6 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index ec6ef31197..2620d28b4b 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -98,9 +98,10 @@ OPTIONS options. --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`. + 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. --done:: Require a `done` command at the end of the stream. @@ -478,9 +479,9 @@ 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. @@ -942,6 +943,9 @@ 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 +979,7 @@ 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 +995,9 @@ 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 @@ -1079,6 +1086,35 @@ 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 |