made the pack completely portable and wrote relevent bat files to go with it
This commit is contained in:
844
gitportable/mingw64/share/doc/git-doc/gitprotocol-v2.adoc
Normal file
844
gitportable/mingw64/share/doc/git-doc/gitprotocol-v2.adoc
Normal file
@@ -0,0 +1,844 @@
|
||||
gitprotocol-v2(5)
|
||||
=================
|
||||
|
||||
NAME
|
||||
----
|
||||
gitprotocol-v2 - Git Wire Protocol, Version 2
|
||||
|
||||
SYNOPSIS
|
||||
--------
|
||||
[verse]
|
||||
<over-the-wire-protocol>
|
||||
|
||||
DESCRIPTION
|
||||
-----------
|
||||
|
||||
This document presents a specification for a version 2 of Git's wire
|
||||
protocol. Protocol v2 will improve upon v1 in the following ways:
|
||||
|
||||
* Instead of multiple service names, multiple commands will be
|
||||
supported by a single service
|
||||
* Easily extendable as capabilities are moved into their own section
|
||||
of the protocol, no longer being hidden behind a NUL byte and
|
||||
limited by the size of a pkt-line
|
||||
* Separate out other information hidden behind NUL bytes (e.g. agent
|
||||
string as a capability and symrefs can be requested using 'ls-refs')
|
||||
* Reference advertisement will be omitted unless explicitly requested
|
||||
* ls-refs command to explicitly request some refs
|
||||
* Designed with http and stateless-rpc in mind. With clear flush
|
||||
semantics the http remote helper can simply act as a proxy
|
||||
|
||||
In protocol v2 communication is command oriented. When first contacting a
|
||||
server a list of capabilities will be advertised. Some of these capabilities
|
||||
will be commands which a client can request be executed. Once a command
|
||||
has completed, a client can reuse the connection and request that other
|
||||
commands be executed.
|
||||
|
||||
Packet-Line Framing
|
||||
-------------------
|
||||
|
||||
All communication is done using packet-line framing, just as in v1. See
|
||||
linkgit:gitprotocol-pack[5] and linkgit:gitprotocol-common[5] for more information.
|
||||
|
||||
In protocol v2 these special packets will have the following semantics:
|
||||
|
||||
* '0000' Flush Packet (flush-pkt) - indicates the end of a message
|
||||
* '0001' Delimiter Packet (delim-pkt) - separates sections of a message
|
||||
* '0002' Response End Packet (response-end-pkt) - indicates the end of a
|
||||
response for stateless connections
|
||||
|
||||
Initial Client Request
|
||||
----------------------
|
||||
|
||||
In general a client can request to speak protocol v2 by sending
|
||||
`version=2` through the respective side-channel for the transport being
|
||||
used which inevitably sets `GIT_PROTOCOL`. More information can be
|
||||
found in linkgit:gitprotocol-pack[5] and linkgit:gitprotocol-http[5], as well as the
|
||||
`GIT_PROTOCOL` definition in `git.txt`. In all cases the
|
||||
response from the server is the capability advertisement.
|
||||
|
||||
Git Transport
|
||||
~~~~~~~~~~~~~
|
||||
|
||||
When using the git:// transport, you can request to use protocol v2 by
|
||||
sending "version=2" as an extra parameter:
|
||||
|
||||
003egit-upload-pack /project.git\0host=myserver.com\0\0version=2\0
|
||||
|
||||
SSH and File Transport
|
||||
~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
When using either the ssh:// or file:// transport, the GIT_PROTOCOL
|
||||
environment variable must be set explicitly to include "version=2".
|
||||
The server may need to be configured to allow this environment variable
|
||||
to pass.
|
||||
|
||||
HTTP Transport
|
||||
~~~~~~~~~~~~~~
|
||||
|
||||
When using the http:// or https:// transport a client makes a "smart"
|
||||
info/refs request as described in linkgit:gitprotocol-http[5] and requests that
|
||||
v2 be used by supplying "version=2" in the `Git-Protocol` header.
|
||||
|
||||
C: GET $GIT_URL/info/refs?service=git-upload-pack HTTP/1.0
|
||||
C: Git-Protocol: version=2
|
||||
|
||||
A v2 server would reply:
|
||||
|
||||
S: 200 OK
|
||||
S: <Some headers>
|
||||
S: ...
|
||||
S:
|
||||
S: 000eversion 2\n
|
||||
S: <capability-advertisement>
|
||||
|
||||
Subsequent requests are then made directly to the service
|
||||
`$GIT_URL/git-upload-pack`. (This works the same for git-receive-pack).
|
||||
|
||||
Uses the `--http-backend-info-refs` option to
|
||||
linkgit:git-upload-pack[1].
|
||||
|
||||
The server may need to be configured to pass this header's contents via
|
||||
the `GIT_PROTOCOL` variable. See the discussion in `git-http-backend.txt`.
|
||||
|
||||
Capability Advertisement
|
||||
------------------------
|
||||
|
||||
A server which decides to communicate (based on a request from a client)
|
||||
using protocol version 2, notifies the client by sending a version string
|
||||
in its initial response followed by an advertisement of its capabilities.
|
||||
Each capability is a key with an optional value. Clients must ignore all
|
||||
unknown keys. Semantics of unknown values are left to the definition of
|
||||
each key. Some capabilities will describe commands which can be requested
|
||||
to be executed by the client.
|
||||
|
||||
capability-advertisement = protocol-version
|
||||
capability-list
|
||||
flush-pkt
|
||||
|
||||
protocol-version = PKT-LINE("version 2" LF)
|
||||
capability-list = *capability
|
||||
capability = PKT-LINE(key[=value] LF)
|
||||
|
||||
key = 1*(ALPHA | DIGIT | "-_")
|
||||
value = 1*(ALPHA | DIGIT | " -_.,?\/{}[]()<>!@#$%^&*+=:;")
|
||||
|
||||
Command Request
|
||||
---------------
|
||||
|
||||
After receiving the capability advertisement, a client can then issue a
|
||||
request to select the command it wants with any particular capabilities
|
||||
or arguments. There is then an optional section where the client can
|
||||
provide any command specific parameters or queries. Only a single
|
||||
command can be requested at a time.
|
||||
|
||||
request = empty-request | command-request
|
||||
empty-request = flush-pkt
|
||||
command-request = command
|
||||
capability-list
|
||||
delim-pkt
|
||||
command-args
|
||||
flush-pkt
|
||||
command = PKT-LINE("command=" key LF)
|
||||
command-args = *command-specific-arg
|
||||
|
||||
command-specific-args are packet line framed arguments defined by
|
||||
each individual command.
|
||||
|
||||
The server will then check to ensure that the client's request is
|
||||
comprised of a valid command as well as valid capabilities which were
|
||||
advertised. If the request is valid the server will then execute the
|
||||
command. A server MUST wait till it has received the client's entire
|
||||
request before issuing a response. The format of the response is
|
||||
determined by the command being executed, but in all cases a flush-pkt
|
||||
indicates the end of the response.
|
||||
|
||||
When a command has finished, and the client has received the entire
|
||||
response from the server, a client can either request that another
|
||||
command be executed or can terminate the connection. A client may
|
||||
optionally send an empty request consisting of just a flush-pkt to
|
||||
indicate that no more requests will be made.
|
||||
|
||||
Capabilities
|
||||
------------
|
||||
|
||||
There are two different types of capabilities: normal capabilities,
|
||||
which can be used to convey information or alter the behavior of a
|
||||
request, and commands, which are the core actions that a client wants to
|
||||
perform (fetch, push, etc).
|
||||
|
||||
Protocol version 2 is stateless by default. This means that all commands
|
||||
must only last a single round and be stateless from the perspective of the
|
||||
server side, unless the client has requested a capability indicating that
|
||||
state should be maintained by the server. Clients MUST NOT require state
|
||||
management on the server side in order to function correctly. This
|
||||
permits simple round-robin load-balancing on the server side, without
|
||||
needing to worry about state management.
|
||||
|
||||
agent
|
||||
~~~~~
|
||||
|
||||
The server can advertise the `agent` capability with a value `X` (in the
|
||||
form `agent=X`) to notify the client that the server is running version
|
||||
`X`. The client may optionally send its own agent string by including
|
||||
the `agent` capability with a value `Y` (in the form `agent=Y`) in its
|
||||
request to the server (but it MUST NOT do so if the server did not
|
||||
advertise the agent capability). The `X` and `Y` strings may contain any
|
||||
printable ASCII characters except space (i.e., the byte range 33 <= x <=
|
||||
126), and are typically of the form "package/version-os" (e.g.,
|
||||
"git/1.8.3.1-Linux") where `os` is the operating system name (e.g.,
|
||||
"Linux"). `X` and `Y` can be configured using the GIT_USER_AGENT
|
||||
environment variable and it takes priority. The `os` is
|
||||
retrieved using the 'sysname' field of the `uname(2)` system call
|
||||
or its equivalent. The agent strings are purely informative for statistics
|
||||
and debugging purposes, and MUST NOT be used to programmatically assume
|
||||
the presence or absence of particular features.
|
||||
|
||||
ls-refs
|
||||
~~~~~~~
|
||||
|
||||
`ls-refs` is the command used to request a reference advertisement in v2.
|
||||
Unlike the current reference advertisement, ls-refs takes in arguments
|
||||
which can be used to limit the refs sent from the server.
|
||||
|
||||
Additional features not supported in the base command will be advertised
|
||||
as the value of the command in the capability advertisement in the form
|
||||
of a space separated list of features: "<command>=<feature-1> <feature-2>"
|
||||
|
||||
ls-refs takes in the following arguments:
|
||||
|
||||
symrefs
|
||||
In addition to the object pointed by it, show the underlying ref
|
||||
pointed by it when showing a symbolic ref.
|
||||
peel
|
||||
Show peeled tags.
|
||||
ref-prefix <prefix>
|
||||
When specified, only references having a prefix matching one of
|
||||
the provided prefixes are displayed. Multiple instances may be
|
||||
given, in which case references matching any prefix will be
|
||||
shown. Note that this is purely for optimization; a server MAY
|
||||
show refs not matching the prefix if it chooses, and clients
|
||||
should filter the result themselves.
|
||||
|
||||
If the 'unborn' feature is advertised the following argument can be
|
||||
included in the client's request.
|
||||
|
||||
unborn
|
||||
The server will send information about HEAD even if it is a symref
|
||||
pointing to an unborn branch in the form "unborn HEAD
|
||||
symref-target:<target>".
|
||||
|
||||
The output of ls-refs is as follows:
|
||||
|
||||
output = *ref
|
||||
flush-pkt
|
||||
obj-id-or-unborn = (obj-id | "unborn")
|
||||
ref = PKT-LINE(obj-id-or-unborn SP refname *(SP ref-attribute) LF)
|
||||
ref-attribute = (symref | peeled)
|
||||
symref = "symref-target:" symref-target
|
||||
peeled = "peeled:" obj-id
|
||||
|
||||
fetch
|
||||
~~~~~
|
||||
|
||||
`fetch` is the command used to fetch a packfile in v2. It can be looked
|
||||
at as a modified version of the v1 fetch where the ref-advertisement is
|
||||
stripped out (since the `ls-refs` command fills that role) and the
|
||||
message format is tweaked to eliminate redundancies and permit easy
|
||||
addition of future extensions.
|
||||
|
||||
Additional features not supported in the base command will be advertised
|
||||
as the value of the command in the capability advertisement in the form
|
||||
of a space separated list of features: "<command>=<feature-1> <feature-2>"
|
||||
|
||||
A `fetch` request can take the following arguments:
|
||||
|
||||
want <oid>
|
||||
Indicates to the server an object which the client wants to
|
||||
retrieve. Wants can be anything and are not limited to
|
||||
advertised objects.
|
||||
|
||||
have <oid>
|
||||
Indicates to the server an object which the client has locally.
|
||||
This allows the server to make a packfile which only contains
|
||||
the objects that the client needs. Multiple 'have' lines can be
|
||||
supplied.
|
||||
|
||||
done
|
||||
Indicates to the server that negotiation should terminate (or
|
||||
not even begin if performing a clone) and that the server should
|
||||
use the information supplied in the request to construct the
|
||||
packfile.
|
||||
|
||||
thin-pack
|
||||
Request that a thin pack be sent, which is a pack with deltas
|
||||
which reference base objects not contained within the pack (but
|
||||
are known to exist at the receiving end). This can reduce the
|
||||
network traffic significantly, but it requires the receiving end
|
||||
to know how to "thicken" these packs by adding the missing bases
|
||||
to the pack.
|
||||
|
||||
no-progress
|
||||
Request that progress information that would normally be sent on
|
||||
side-band channel 2, during the packfile transfer, should not be
|
||||
sent. However, the side-band channel 3 is still used for error
|
||||
responses.
|
||||
|
||||
include-tag
|
||||
Request that annotated tags should be sent if the objects they
|
||||
point to are being sent.
|
||||
|
||||
ofs-delta
|
||||
Indicate that the client understands PACKv2 with delta referring
|
||||
to its base by position in pack rather than by an oid. That is,
|
||||
they can read OBJ_OFS_DELTA (aka type 6) in a packfile.
|
||||
|
||||
If the 'shallow' feature is advertised the following arguments can be
|
||||
included in the clients request as well as the potential addition of the
|
||||
'shallow-info' section in the server's response as explained below.
|
||||
|
||||
shallow <oid>
|
||||
A client must notify the server of all commits for which it only
|
||||
has shallow copies (meaning that it doesn't have the parents of
|
||||
a commit) by supplying a 'shallow <oid>' line for each such
|
||||
object so that the server is aware of the limitations of the
|
||||
client's history. This is so that the server is aware that the
|
||||
client may not have all objects reachable from such commits.
|
||||
|
||||
deepen <depth>
|
||||
Requests that the fetch/clone should be shallow having a commit
|
||||
depth of <depth> relative to the remote side.
|
||||
|
||||
deepen-relative
|
||||
Requests that the semantics of the "deepen" command be changed
|
||||
to indicate that the depth requested is relative to the client's
|
||||
current shallow boundary, instead of relative to the requested
|
||||
commits.
|
||||
|
||||
deepen-since <timestamp>
|
||||
Requests that the shallow clone/fetch should be cut at a
|
||||
specific time, instead of depth. Internally it's equivalent to
|
||||
doing "git rev-list --max-age=<timestamp>". Cannot be used with
|
||||
"deepen".
|
||||
|
||||
deepen-not <rev>
|
||||
Requests that the shallow clone/fetch should be cut at a
|
||||
specific revision specified by '<rev>', instead of a depth.
|
||||
Internally it's equivalent of doing "git rev-list --not <rev>".
|
||||
Cannot be used with "deepen", but can be used with
|
||||
"deepen-since".
|
||||
|
||||
If the 'filter' feature is advertised, the following argument can be
|
||||
included in the client's request:
|
||||
|
||||
filter <filter-spec>
|
||||
Request that various objects from the packfile be omitted
|
||||
using one of several filtering techniques. These are intended
|
||||
for use with partial clone and partial fetch operations. See
|
||||
`rev-list` for possible "filter-spec" values. When communicating
|
||||
with other processes, senders SHOULD translate scaled integers
|
||||
(e.g. "1k") into a fully-expanded form (e.g. "1024") to aid
|
||||
interoperability with older receivers that may not understand
|
||||
newly-invented scaling suffixes. However, receivers SHOULD
|
||||
accept the following suffixes: 'k', 'm', and 'g' for 1024,
|
||||
1048576, and 1073741824, respectively.
|
||||
|
||||
If the 'ref-in-want' feature is advertised, the following argument can
|
||||
be included in the client's request as well as the potential addition of
|
||||
the 'wanted-refs' section in the server's response as explained below.
|
||||
|
||||
want-ref <ref>
|
||||
Indicates to the server that the client wants to retrieve a
|
||||
particular ref, where <ref> is the full name of a ref on the
|
||||
server. It is a protocol error to send want-ref for the
|
||||
same ref more than once.
|
||||
|
||||
If the 'sideband-all' feature is advertised, the following argument can be
|
||||
included in the client's request:
|
||||
|
||||
sideband-all
|
||||
Instruct the server to send the whole response multiplexed, not just
|
||||
the packfile section. All non-flush and non-delim PKT-LINE in the
|
||||
response (not only in the packfile section) will then start with a byte
|
||||
indicating its sideband (1, 2, or 3), and the server may send "0005\2"
|
||||
(a PKT-LINE of sideband 2 with no payload) as a keepalive packet.
|
||||
|
||||
If the 'packfile-uris' feature is advertised, the following argument
|
||||
can be included in the client's request as well as the potential
|
||||
addition of the 'packfile-uris' section in the server's response as
|
||||
explained below. Note that at most one `packfile-uris` line can be sent
|
||||
to the server.
|
||||
|
||||
packfile-uris <comma-separated-list-of-protocols>
|
||||
Indicates to the server that the client is willing to receive
|
||||
URIs of any of the given protocols in place of objects in the
|
||||
sent packfile. Before performing the connectivity check, the
|
||||
client should download from all given URIs. Currently, the
|
||||
protocols supported are "http" and "https".
|
||||
|
||||
If the 'wait-for-done' feature is advertised, the following argument
|
||||
can be included in the client's request.
|
||||
|
||||
wait-for-done
|
||||
Indicates to the server that it should never send "ready", but
|
||||
should wait for the client to say "done" before sending the
|
||||
packfile.
|
||||
|
||||
The response of `fetch` is broken into a number of sections separated by
|
||||
delimiter packets (0001), with each section beginning with its section
|
||||
header. Most sections are sent only when the packfile is sent.
|
||||
|
||||
output = acknowledgements flush-pkt |
|
||||
[acknowledgments delim-pkt] [shallow-info delim-pkt]
|
||||
[wanted-refs delim-pkt] [packfile-uris delim-pkt]
|
||||
packfile flush-pkt
|
||||
|
||||
acknowledgments = PKT-LINE("acknowledgments" LF)
|
||||
(nak | *ack)
|
||||
(ready)
|
||||
ready = PKT-LINE("ready" LF)
|
||||
nak = PKT-LINE("NAK" LF)
|
||||
ack = PKT-LINE("ACK" SP obj-id LF)
|
||||
|
||||
shallow-info = PKT-LINE("shallow-info" LF)
|
||||
*PKT-LINE((shallow | unshallow) LF)
|
||||
shallow = "shallow" SP obj-id
|
||||
unshallow = "unshallow" SP obj-id
|
||||
|
||||
wanted-refs = PKT-LINE("wanted-refs" LF)
|
||||
*PKT-LINE(wanted-ref LF)
|
||||
wanted-ref = obj-id SP refname
|
||||
|
||||
packfile-uris = PKT-LINE("packfile-uris" LF) *packfile-uri
|
||||
packfile-uri = PKT-LINE(40*(HEXDIGIT) SP *%x20-ff LF)
|
||||
|
||||
packfile = PKT-LINE("packfile" LF)
|
||||
*PKT-LINE(%x01-03 *%x00-ff)
|
||||
|
||||
acknowledgments section
|
||||
* If the client determines that it is finished with negotiations by
|
||||
sending a "done" line (thus requiring the server to send a packfile),
|
||||
the acknowledgments sections MUST be omitted from the server's
|
||||
response.
|
||||
|
||||
* Always begins with the section header "acknowledgments"
|
||||
|
||||
* The server will respond with "NAK" if none of the object ids sent
|
||||
as have lines were common.
|
||||
|
||||
* The server will respond with "ACK obj-id" for all of the
|
||||
object ids sent as have lines which are common.
|
||||
|
||||
* A response cannot have both "ACK" lines as well as a "NAK"
|
||||
line.
|
||||
|
||||
* The server will respond with a "ready" line indicating that
|
||||
the server has found an acceptable common base and is ready to
|
||||
make and send a packfile (which will be found in the packfile
|
||||
section of the same response)
|
||||
|
||||
* If the server has found a suitable cut point and has decided
|
||||
to send a "ready" line, then the server can decide to (as an
|
||||
optimization) omit any "ACK" lines it would have sent during
|
||||
its response. This is because the server will have already
|
||||
determined the objects it plans to send to the client and no
|
||||
further negotiation is needed.
|
||||
|
||||
shallow-info section
|
||||
* If the client has requested a shallow fetch/clone, a shallow
|
||||
client requests a fetch or the server is shallow then the
|
||||
server's response may include a shallow-info section. The
|
||||
shallow-info section will be included if (due to one of the
|
||||
above conditions) the server needs to inform the client of any
|
||||
shallow boundaries or adjustments to the clients already
|
||||
existing shallow boundaries.
|
||||
|
||||
* Always begins with the section header "shallow-info"
|
||||
|
||||
* If a positive depth is requested, the server will compute the
|
||||
set of commits which are no deeper than the desired depth.
|
||||
|
||||
* The server sends a "shallow obj-id" line for each commit whose
|
||||
parents will not be sent in the following packfile.
|
||||
|
||||
* The server sends an "unshallow obj-id" line for each commit
|
||||
which the client has indicated is shallow, but is no longer
|
||||
shallow as a result of the fetch (due to its parents being
|
||||
sent in the following packfile).
|
||||
|
||||
* The server MUST NOT send any "unshallow" lines for anything
|
||||
which the client has not indicated was shallow as a part of
|
||||
its request.
|
||||
|
||||
wanted-refs section
|
||||
* This section is only included if the client has requested a
|
||||
ref using a 'want-ref' line and if a packfile section is also
|
||||
included in the response.
|
||||
|
||||
* Always begins with the section header "wanted-refs".
|
||||
|
||||
* The server will send a ref listing ("<oid> <refname>") for
|
||||
each reference requested using 'want-ref' lines.
|
||||
|
||||
* The server MUST NOT send any refs which were not requested
|
||||
using 'want-ref' lines.
|
||||
|
||||
packfile-uris section
|
||||
* This section is only included if the client sent
|
||||
'packfile-uris' and the server has at least one such URI to
|
||||
send.
|
||||
|
||||
* Always begins with the section header "packfile-uris".
|
||||
|
||||
* For each URI the server sends, it sends a hash of the pack's
|
||||
contents (as output by git index-pack) followed by the URI.
|
||||
|
||||
* The hashes are 40 hex characters long. When Git upgrades to a new
|
||||
hash algorithm, this might need to be updated. (It should match
|
||||
whatever index-pack outputs after "pack\t" or "keep\t".
|
||||
|
||||
packfile section
|
||||
* This section is only included if the client has sent 'want'
|
||||
lines in its request and either requested that no more
|
||||
negotiation be done by sending 'done' or if the server has
|
||||
decided it has found a sufficient cut point to produce a
|
||||
packfile.
|
||||
|
||||
* Always begins with the section header "packfile"
|
||||
|
||||
* The transmission of the packfile begins immediately after the
|
||||
section header
|
||||
|
||||
* The data transfer of the packfile is always multiplexed, using
|
||||
the same semantics of the 'side-band-64k' capability from
|
||||
protocol version 1. This means that each packet, during the
|
||||
packfile data stream, is made up of a leading 4-byte pkt-line
|
||||
length (typical of the pkt-line format), followed by a 1-byte
|
||||
stream code, followed by the actual data.
|
||||
|
||||
The stream code can be one of:
|
||||
1 - pack data
|
||||
2 - progress messages
|
||||
3 - fatal error message just before stream aborts
|
||||
|
||||
server-option
|
||||
~~~~~~~~~~~~~
|
||||
|
||||
If advertised, indicates that any number of server specific options can be
|
||||
included in a request. This is done by sending each option as a
|
||||
"server-option=<option>" capability line in the capability-list section of
|
||||
a request.
|
||||
|
||||
The provided options must not contain a NUL or LF character.
|
||||
|
||||
object-format
|
||||
~~~~~~~~~~~~~
|
||||
|
||||
The server can advertise the `object-format` capability with a value `X` (in the
|
||||
form `object-format=X`) to notify the client that the server is able to deal
|
||||
with objects using hash algorithm X. If not specified, the server is assumed to
|
||||
only handle SHA-1. If the client would like to use a hash algorithm other than
|
||||
SHA-1, it should specify its object-format string.
|
||||
|
||||
session-id=<session-id>
|
||||
~~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
The server may advertise a session ID that can be used to identify this process
|
||||
across multiple requests. The client may advertise its own session ID back to
|
||||
the server as well.
|
||||
|
||||
Session IDs should be unique to a given process. They must fit within a
|
||||
packet-line, and must not contain non-printable or whitespace characters. The
|
||||
current implementation uses trace2 session IDs (see
|
||||
link:technical/api-trace2.html[api-trace2] for details), but this may change
|
||||
and users of the session ID should not rely on this fact.
|
||||
|
||||
object-info
|
||||
~~~~~~~~~~~
|
||||
|
||||
`object-info` is the command to retrieve information about one or more objects.
|
||||
Its main purpose is to allow a client to make decisions based on this
|
||||
information without having to fully fetch objects. Object size is the only
|
||||
information that is currently supported.
|
||||
|
||||
An `object-info` request takes the following arguments:
|
||||
|
||||
size
|
||||
Requests size information to be returned for each listed object id.
|
||||
|
||||
oid <oid>
|
||||
Indicates to the server an object which the client wants to obtain
|
||||
information for.
|
||||
|
||||
The response of `object-info` is a list of the requested object ids
|
||||
and associated requested information, each separated by a single space.
|
||||
|
||||
output = info flush-pkt
|
||||
|
||||
info = PKT-LINE(attrs) LF)
|
||||
*PKT-LINE(obj-info LF)
|
||||
|
||||
attrs = attr | attrs SP attrs
|
||||
|
||||
attr = "size"
|
||||
|
||||
obj-info = obj-id SP obj-size
|
||||
|
||||
bundle-uri
|
||||
~~~~~~~~~~
|
||||
|
||||
If the 'bundle-uri' capability is advertised, the server supports the
|
||||
`bundle-uri' command.
|
||||
|
||||
The capability is currently advertised with no value (i.e. not
|
||||
"bundle-uri=somevalue"), a value may be added in the future for
|
||||
supporting command-wide extensions. Clients MUST ignore any unknown
|
||||
capability values and proceed with the 'bundle-uri` dialog they
|
||||
support.
|
||||
|
||||
The 'bundle-uri' command is intended to be issued before `fetch` to
|
||||
get URIs to bundle files (see linkgit:git-bundle[1]) to "seed" and
|
||||
inform the subsequent `fetch` command.
|
||||
|
||||
The client CAN issue `bundle-uri` before or after any other valid
|
||||
command. To be useful to clients it's expected that it'll be issued
|
||||
after an `ls-refs` and before `fetch`, but CAN be issued at any time
|
||||
in the dialog.
|
||||
|
||||
DISCUSSION of bundle-uri
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
The intent of the feature is optimize for server resource consumption
|
||||
in the common case by changing the common case of fetching a very
|
||||
large PACK during linkgit:git-clone[1] into a smaller incremental
|
||||
fetch.
|
||||
|
||||
It also allows servers to achieve better caching in combination with
|
||||
an `uploadpack.packObjectsHook` (see linkgit:git-config[1]).
|
||||
|
||||
By having new clones or fetches be a more predictable and common
|
||||
negotiation against the tips of recently produces *.bundle file(s).
|
||||
Servers might even pre-generate the results of such negotiations for
|
||||
the `uploadpack.packObjectsHook` as new pushes come in.
|
||||
|
||||
One way that servers could take advantage of these bundles is that the
|
||||
server would anticipate that fresh clones will download a known bundle,
|
||||
followed by catching up to the current state of the repository using ref
|
||||
tips found in that bundle (or bundles).
|
||||
|
||||
PROTOCOL for bundle-uri
|
||||
^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
A `bundle-uri` request takes no arguments, and as noted above does not
|
||||
currently advertise a capability value. Both may be added in the
|
||||
future.
|
||||
|
||||
When the client issues a `command=bundle-uri` request, the response is a
|
||||
list of key-value pairs provided as packet lines with value
|
||||
`<key>=<value>`. Each `<key>` should be interpreted as a config key from
|
||||
the `bundle.*` namespace to construct a list of bundles. These keys are
|
||||
grouped by a `bundle.<id>.` subsection, where each key corresponding to a
|
||||
given `<id>` contributes attributes to the bundle defined by that `<id>`.
|
||||
See linkgit:git-config[1] for the specific details of these keys and how
|
||||
the Git client will interpret their values.
|
||||
|
||||
Clients MUST parse the line according to the above format, lines that do
|
||||
not conform to the format SHOULD be discarded. The user MAY be warned in
|
||||
such a case.
|
||||
|
||||
bundle-uri CLIENT AND SERVER EXPECTATIONS
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
URI CONTENTS::
|
||||
The content at the advertised URIs MUST be one of two types.
|
||||
+
|
||||
The advertised URI may contain a bundle file that `git bundle verify`
|
||||
would accept. I.e. they MUST contain one or more reference tips for
|
||||
use by the client, MUST indicate prerequisites (in any) with standard
|
||||
"-" prefixes, and MUST indicate their "object-format", if
|
||||
applicable.
|
||||
+
|
||||
The advertised URI may alternatively contain a plaintext file that `git
|
||||
config --list` would accept (with the `--file` option). The key-value
|
||||
pairs in this list are in the `bundle.*` namespace (see
|
||||
linkgit:git-config[1]).
|
||||
|
||||
bundle-uri CLIENT ERROR RECOVERY::
|
||||
A client MUST above all gracefully degrade on errors, whether that
|
||||
error is because of bad missing/data in the bundle URI(s), because
|
||||
that client is too dumb to e.g. understand and fully parse out bundle
|
||||
headers and their prerequisite relationships, or something else.
|
||||
+
|
||||
Server operators should feel confident in turning on "bundle-uri" and
|
||||
not worry if e.g. their CDN goes down that clones or fetches will run
|
||||
into hard failures. Even if the server bundle(s) are
|
||||
incomplete, or bad in some way the client should still end up with a
|
||||
functioning repository, just as if it had chosen not to use this
|
||||
protocol extension.
|
||||
+
|
||||
All subsequent discussion on client and server interaction MUST keep
|
||||
this in mind.
|
||||
|
||||
bundle-uri SERVER TO CLIENT::
|
||||
The ordering of the returned bundle uris is not significant. Clients
|
||||
MUST parse their headers to discover their contained OIDS and
|
||||
prerequisites. A client MUST consider the content of the bundle(s)
|
||||
themselves and their header as the ultimate source of truth.
|
||||
+
|
||||
A server MAY even return bundle(s) that don't have any direct
|
||||
relationship to the repository being cloned (either through accident,
|
||||
or intentional "clever" configuration), and expect a client to sort
|
||||
out what data they'd like from the bundle(s), if any.
|
||||
|
||||
bundle-uri CLIENT TO SERVER::
|
||||
The client SHOULD provide reference tips found in the bundle header(s)
|
||||
as 'have' lines in any subsequent `fetch` request. A client MAY also
|
||||
ignore the bundle(s) entirely if doing so is deemed worse for some
|
||||
reason, e.g. if the bundles can't be downloaded, it doesn't like the
|
||||
tips it finds etc.
|
||||
|
||||
WHEN ADVERTISED BUNDLE(S) REQUIRE NO FURTHER NEGOTIATION::
|
||||
If after issuing `bundle-uri` and `ls-refs`, and getting the header(s)
|
||||
of the bundle(s) the client finds that the ref tips it wants can be
|
||||
retrieved entirely from advertised bundle(s), the client MAY disconnect
|
||||
from the Git server. The results of such a 'clone' or 'fetch' should be
|
||||
indistinguishable from the state attained without using bundle-uri.
|
||||
|
||||
EARLY CLIENT DISCONNECTIONS AND ERROR RECOVERY::
|
||||
A client MAY perform an early disconnect while still downloading the
|
||||
bundle(s) (having streamed and parsed their headers). In such a case
|
||||
the client MUST gracefully recover from any errors related to
|
||||
finishing the download and validation of the bundle(s).
|
||||
+
|
||||
I.e. a client might need to re-connect and issue a 'fetch' command,
|
||||
and possibly fall back to not making use of 'bundle-uri' at all.
|
||||
+
|
||||
This "MAY" behavior is specified as such (and not a "SHOULD") on the
|
||||
assumption that a server advertising bundle uris is more likely than
|
||||
not to be serving up a relatively large repository, and to be pointing
|
||||
to URIs that have a good chance of being in working order. A client
|
||||
MAY e.g. look at the payload size of the bundles as a heuristic to see
|
||||
if an early disconnect is worth it, should falling back on a full
|
||||
"fetch" dialog be necessary.
|
||||
|
||||
WHEN ADVERTISED BUNDLE(S) REQUIRE FURTHER NEGOTIATION::
|
||||
A client SHOULD commence a negotiation of a PACK from the server via
|
||||
the "fetch" command using the OID tips found in advertised bundles,
|
||||
even if's still in the process of downloading those bundle(s).
|
||||
+
|
||||
This allows for aggressive early disconnects from any interactive
|
||||
server dialog. The client blindly trusts that the advertised OID tips
|
||||
are relevant, and issues them as 'have' lines, it then requests any
|
||||
tips it would like (usually from the "ls-refs" advertisement) via
|
||||
'want' lines. The server will then compute a (hopefully small) PACK
|
||||
with the expected difference between the tips from the bundle(s) and
|
||||
the data requested.
|
||||
+
|
||||
The only connection the client then needs to keep active is to the
|
||||
concurrently downloading static bundle(s), when those and the
|
||||
incremental PACK are retrieved they should be inflated and
|
||||
validated. Any errors at this point should be gracefully recovered
|
||||
from, see above.
|
||||
|
||||
bundle-uri PROTOCOL FEATURES
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
The client constructs a bundle list from the `<key>=<value>` pairs
|
||||
provided by the server. These pairs are part of the `bundle.*` namespace
|
||||
as documented in linkgit:git-config[1]. In this section, we discuss some
|
||||
of these keys and describe the actions the client will do in response to
|
||||
this information.
|
||||
|
||||
In particular, the `bundle.version` key specifies an integer value. The
|
||||
only accepted value at the moment is `1`, but if the client sees an
|
||||
unexpected value here then the client MUST ignore the bundle list.
|
||||
|
||||
As long as `bundle.version` is understood, all other unknown keys MAY be
|
||||
ignored by the client. The server will guarantee compatibility with older
|
||||
clients, though newer clients may be better able to use the extra keys to
|
||||
minimize downloads.
|
||||
|
||||
Any backwards-incompatible addition of pre-URI key-value will be
|
||||
guarded by a new `bundle.version` value or values in 'bundle-uri'
|
||||
capability advertisement itself, and/or by new future `bundle-uri`
|
||||
request arguments.
|
||||
|
||||
Some example key-value pairs that are not currently implemented but could
|
||||
be implemented in the future include:
|
||||
|
||||
* Add a "hash=<val>" or "size=<bytes>" advertise the expected hash or
|
||||
size of the bundle file.
|
||||
|
||||
* Advertise that one or more bundle files are the same (to e.g. have
|
||||
clients round-robin or otherwise choose one of N possible files).
|
||||
|
||||
* A "oid=<OID>" shortcut and "prerequisite=<OID>" shortcut. For
|
||||
expressing the common case of a bundle with one tip and no
|
||||
prerequisites, or one tip and one prerequisite.
|
||||
+
|
||||
This would allow for optimizing the common case of servers who'd like
|
||||
to provide one "big bundle" containing only their "main" branch,
|
||||
and/or incremental updates thereof.
|
||||
+
|
||||
A client receiving such a response MAY assume that they can skip
|
||||
retrieving the header from a bundle at the indicated URI, and thus
|
||||
save themselves and the server(s) the request(s) needed to inspect the
|
||||
headers of that bundle or bundles.
|
||||
|
||||
promisor-remote=<pr-infos>
|
||||
~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
The server may advertise some promisor remotes it is using or knows
|
||||
about to a client which may want to use them as its promisor remotes,
|
||||
instead of this repository. In this case <pr-infos> should be of the
|
||||
form:
|
||||
|
||||
pr-infos = pr-info | pr-infos ";" pr-info
|
||||
|
||||
pr-info = "name=" pr-name | "name=" pr-name "," "url=" pr-url
|
||||
|
||||
where `pr-name` is the urlencoded name of a promisor remote, and
|
||||
`pr-url` the urlencoded URL of that promisor remote.
|
||||
|
||||
In this case, if the client decides to use one or more promisor
|
||||
remotes the server advertised, it can reply with
|
||||
"promisor-remote=<pr-names>" where <pr-names> should be of the form:
|
||||
|
||||
pr-names = pr-name | pr-names ";" pr-name
|
||||
|
||||
where `pr-name` is the urlencoded name of a promisor remote the server
|
||||
advertised and the client accepts.
|
||||
|
||||
Note that, everywhere in this document, `pr-name` MUST be a valid
|
||||
remote name, and the ';' and ',' characters MUST be encoded if they
|
||||
appear in `pr-name` or `pr-url`.
|
||||
|
||||
If the server doesn't know any promisor remote that could be good for
|
||||
a client to use, or prefers a client not to use any promisor remote it
|
||||
uses or knows about, it shouldn't advertise the "promisor-remote"
|
||||
capability at all.
|
||||
|
||||
In this case, or if the client doesn't want to use any promisor remote
|
||||
the server advertised, the client shouldn't advertise the
|
||||
"promisor-remote" capability at all in its reply.
|
||||
|
||||
The "promisor.advertise" and "promisor.acceptFromServer" configuration
|
||||
options can be used on the server and client side to control what they
|
||||
advertise or accept respectively. See the documentation of these
|
||||
configuration options for more information.
|
||||
|
||||
Note that in the future it would be nice if the "promisor-remote"
|
||||
protocol capability could be used by the server, when responding to
|
||||
`git fetch` or `git clone`, to advertise better-connected remotes that
|
||||
the client can use as promisor remotes, instead of this repository, so
|
||||
that the client can lazily fetch objects from these other
|
||||
better-connected remotes. This would require the server to omit in its
|
||||
response the objects available on the better-connected remotes that
|
||||
the client has accepted. This hasn't been implemented yet though. So
|
||||
for now this "promisor-remote" capability is useful only when the
|
||||
server advertises some promisor remotes it already uses to borrow
|
||||
objects from.
|
||||
|
||||
GIT
|
||||
---
|
||||
Part of the linkgit:git[1] suite
|
||||
Reference in New Issue
Block a user