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authorShawn O. Pearce <spearce@spearce.org>2007-08-01 10:23:08 -0400
committerShawn O. Pearce <spearce@spearce.org>2007-08-19 03:38:36 -0400
commitac053c02029d88c7ed4d7e92949a1586eb3f7704 (patch)
tree84e5e58df838e7f27d8cee33cb1fae6d0f7b6917 /Documentation/git-fast-import.txt
parent1fdb649c6ac4cfc536983077b4851a1959cbc1c4 (diff)
downloadgit-ac053c02029d88c7ed4d7e92949a1586eb3f7704.tar.gz
Allow frontends to bidirectionally communicate with fast-import
The existing checkpoint command is very useful to force fast-import to dump the branches out to disk so that standard Git tools can access them and the objects they refer to. However there was not a way to know when fast-import had finished executing the checkpoint and it was safe to read those refs. The progress command can be used to make fast-import output any message of the frontend's choosing to standard out. The frontend can scan for these messages using select() or poll() to monitor a pipe connected to the standard output of fast-import. Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Diffstat (limited to 'Documentation/git-fast-import.txt')
-rw-r--r--Documentation/git-fast-import.txt39
1 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 1644b90cea..0a019dd2e5 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -298,6 +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
@@ -775,6 +780,31 @@ 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
---------------
The following tips and tricks have been collected from various
@@ -867,6 +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
---------------------