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| author |  Jonathan Tan <jonathantanmy@google.com> | 2018-01-25 10:53:24 -0800 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2018-01-25 11:24:32 -0800 |
| commit | addad10594583092ad92a4b82c40040b913bb8ee (patch) | |
| tree | 7751d1c911e4c213e29aab5d86855779ffa394bf /Documentation/technical | |
| parent | First batch after 2.16 (diff) | |
| download | tgif-addad10594583092ad92a4b82c40040b913bb8ee.tar.xz | |
Docs: split out long-running subprocess handshake
Separating out the implementation of the handshake when starting a
long-running subprocess (for example, as is done for a clean/smudge
filter) was done in commit fa64a2fdbeed ("sub-process: refactor
handshake to common function", 2017-07-26), but its documentation still
resides in gitattributes. Split out the documentation as well.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/long-running-process-protocol.txt | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/Documentation/technical/long-running-process-protocol.txt b/Documentation/technical/long-running-process-protocol.txt new file mode 100644 index 0000000000..aa0aa9af1c --- /dev/null +++ b/Documentation/technical/long-running-process-protocol.txt @@ -0,0 +1,50 @@ +Long-running process protocol +============================= + +This protocol is used when Git needs to communicate with an external +process throughout the entire life of a single Git command. All +communication is in pkt-line format (see technical/protocol-common.txt) +over standard input and standard output. + +Handshake +--------- + +Git starts by sending a welcome message (for example, +"git-filter-client"), a list of supported protocol version numbers, and +a flush packet. Git expects to read the welcome message with "server" +instead of "client" (for example, "git-filter-server"), exactly one +protocol version number from the previously sent list, and a flush +packet. All further communication will be based on the selected version. +The remaining protocol description below documents "version=2". Please +note that "version=42" in the example below does not exist and is only +there to illustrate how the protocol would look like with more than one +version. + +After the version negotiation Git sends a list of all capabilities that +it supports and a flush packet. Git expects to read a list of desired +capabilities, which must be a subset of the supported capabilities list, +and a flush packet as response: +------------------------ +packet: git> git-filter-client +packet: git> version=2 +packet: git> version=42 +packet: git> 0000 +packet: git< git-filter-server +packet: git< version=2 +packet: git< 0000 +packet: git> capability=clean +packet: git> capability=smudge +packet: git> capability=not-yet-invented +packet: git> 0000 +packet: git< capability=clean +packet: git< capability=smudge +packet: git< 0000 +------------------------ + +Shutdown +-------- + +Git will close +the command pipe on exit. The filter is expected to detect EOF +and exit gracefully on its own. Git will wait until the filter +process has stopped. |