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| author | Jonathan Nieder <jrnieder@gmail.com> | 2011-01-02 21:10:59 -0600 |
|---|---|---|
| committer | Jonathan Nieder <jrnieder@gmail.com> | 2011-02-26 04:59:37 -0600 |
| commit | b1c9b798a6dd391aeaea31663a65164815701244 (patch) | |
| tree | adc32fa7f1f4cfaaac28c0f3017c6b247a583136 /vcs-svn/line_buffer.txt | |
| parent | cb3f87cf1ba90373fdc240d65a4d65434099d9a3 (diff) | |
| download | git-b1c9b798a6dd391aeaea31663a65164815701244.tar.gz git-b1c9b798a6dd391aeaea31663a65164815701244.tar.xz | |
vcs-svn: teach line_buffer about temporary files
It can sometimes be useful to write information temporarily to file,
to read back later. These functions allow a program to use the
line_buffer facilities when doing so.
It works like this:
1. find a unique filename with buffer_tmpfile_init.
2. rewind with buffer_tmpfile_rewind. This returns a stdio
handle for writing.
3. when finished writing, declare so with
buffer_tmpfile_prepare_to_read. The return value indicates
how many bytes were written.
4. read whatever portion of the file is needed.
5. if finished, remove the temporary file with buffer_deinit.
otherwise, go back to step 2,
The svn support would use this to buffer the postimage from delta
application until the length is known and fast-import can receive
the resulting blob.
Based-on-patch-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Diffstat (limited to 'vcs-svn/line_buffer.txt')
| -rw-r--r-- | vcs-svn/line_buffer.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/vcs-svn/line_buffer.txt b/vcs-svn/line_buffer.txt index 4e8fb719c..e89cc41d5 100644 --- a/vcs-svn/line_buffer.txt +++ b/vcs-svn/line_buffer.txt @@ -24,6 +24,28 @@ The calling program: When finished, the caller can use `buffer_reset` to deallocate resources. +Using temporary files +--------------------- + +Temporary files provide a place to store data that should not outlive +the calling program. A program + + - initializes a `struct line_buffer` to LINE_BUFFER_INIT + - requests a temporary file with `buffer_tmpfile_init` + - acquires an output handle by calling `buffer_tmpfile_rewind` + - uses standard I/O functions like `fprintf` and `fwrite` to fill + the temporary file + - declares writing is over with `buffer_tmpfile_prepare_to_read` + - can re-read what was written with `buffer_read_line`, + `buffer_read_string`, and so on + - can reuse the temporary file by calling `buffer_tmpfile_rewind` + again + - removes the temporary file with `buffer_deinit`, perhaps to + reuse the line_buffer for some other file. + +When finished, the calling program can use `buffer_reset` to deallocate +resources. + Functions --------- |