git-commit-vandalism/Documentation/technical/api-sub-process.txt
Ben Peart 99605d62e8 sub-process: move sub-process functions into separate files
Move the sub-proces functions into sub-process.h/c.  Add documentation
for the new module in Documentation/technical/api-sub-process.txt

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-15 13:01:57 +09:00

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sub-process API
===============
The sub-process API makes it possible to run background sub-processes
for the entire lifetime of a Git invocation. If Git needs to communicate
with an external process multiple times, then this can reduces the process
invocation overhead. Git and the sub-process communicate through stdin and
stdout.
The sub-processes are kept in a hashmap by command name and looked up
via the subprocess_find_entry function. If an existing instance can not
be found then a new process should be created and started. When the
parent git command terminates, all sub-processes are also terminated.
This API is based on the run-command API.
Data structures
---------------
* `struct subprocess_entry`
The sub-process structure. Members should not be accessed directly.
Types
-----
'int(*subprocess_start_fn)(struct subprocess_entry *entry)'::
User-supplied function to initialize the sub-process. This is
typically used to negotiate the interface version and capabilities.
Functions
---------
`cmd2process_cmp`::
Function to test two subprocess hashmap entries for equality.
`subprocess_start`::
Start a subprocess and add it to the subprocess hashmap.
`subprocess_stop`::
Kill a subprocess and remove it from the subprocess hashmap.
`subprocess_find_entry`::
Find a subprocess in the subprocess hashmap.
`subprocess_get_child_process`::
Get the underlying `struct child_process` from a subprocess.
`subprocess_read_status`::
Helper function to read packets looking for the last "status=<foo>"
key/value pair.