diff options
Diffstat (limited to 'Documentation/technical/protocol-capabilities.txt')
| -rw-r--r-- | Documentation/technical/protocol-capabilities.txt | 114 |
1 files changed, 102 insertions, 12 deletions
diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt index b15517fa06..eaab6b4ac7 100644 --- a/Documentation/technical/protocol-capabilities.txt +++ b/Documentation/technical/protocol-capabilities.txt @@ -18,11 +18,13 @@ was sent. Server MUST NOT ignore capabilities that client requested and server advertised. As a consequence of these rules, server MUST NOT advertise capabilities it does not understand. -The 'report-status' and 'delete-refs' capabilities are sent and -recognized by the receive-pack (push to server) process. +The 'atomic', 'report-status', 'delete-refs', 'quiet', and 'push-cert' +capabilities are sent and recognized by the receive-pack (push to server) +process. -The 'ofs-delta' capability is sent and recognized by both upload-pack -and receive-pack protocols. +The 'ofs-delta' and 'side-band-64k' capabilities are sent and recognized +by both upload-pack and receive-pack protocols. The 'agent' capability +may optionally be sent in both protocols. All other capabilities are only recognized by the upload-pack (fetch from server) process. @@ -68,17 +70,50 @@ ends. Without multi_ack the client would have sent that c-b-a chain anyway, interleaved with S-R-Q. +multi_ack_detailed +------------------ +This is an extension of multi_ack that permits client to better +understand the server's in-memory state. See pack-protocol.txt, +section "Packfile Negotiation" for more information. + +no-done +------- +This capability should only be used with the smart HTTP protocol. If +multi_ack_detailed and no-done are both present, then the sender is +free to immediately send a pack following its first "ACK obj-id ready" +message. + +Without no-done in the smart HTTP protocol, the server session would +end and the client has to make another trip to send "done" before +the server can send the pack. no-done removes the last round and +thus slightly reduces latency. + thin-pack --------- -This capability means that the server can send a 'thin' pack, a pack -which does not contain base objects; if those base objects are available -on client side. Client requests 'thin-pack' capability when it -understands how to "thicken" it by adding required delta bases making -it self-contained. +A thin pack is one 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. + +The upload-pack server advertises 'thin-pack' when it can generate +and send a thin pack. A client requests the 'thin-pack' capability +when it understands how to "thicken" it, notifying the server that +it can receive such a pack. A client MUST NOT request the +'thin-pack' capability if it cannot turn a thin pack into a +self-contained pack. -Client MUST NOT request 'thin-pack' capability if it cannot turn a thin -pack into a self-contained pack. +Receive-pack, on the other hand, is assumed by default to be able to +handle thin packs, but can ask the client not to use the feature by +advertising the 'no-thin' capability. A client MUST NOT send a thin +pack if the server advertises the 'no-thin' capability. + +The reasons for this asymmetry are historical. The receive-pack +program did not exist until after the invention of thin packs, so +historically the reference implementation of receive-pack always +understood thin packs. Adding 'no-thin' later allowed receive-pack +to disable the feature in a backwards-compatible manner. side-band, side-band-64k @@ -123,6 +158,20 @@ Server can send, and client understand PACKv2 with delta referring to its base by position in pack rather than by an obj-id. That is, they can send/read OBJ_OFS_DELTA (aka type 6) in a packfile. +agent +----- + +The server may optionally send a capability of the form `agent=X` to +notify the client that the server is running version `X`. The client may +optionally return its own agent string by responding with an `agent=Y` +capability (but it MUST NOT do so if the server did not mention the +agent capability). The `X` and `Y` strings may contain any printable +ASCII characters except space (i.e., the byte range 32 < x < 127), and +are typically of the form "package/version" (e.g., "git/1.8.3.1"). 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. + shallow ------- @@ -168,7 +217,7 @@ of whether or not there are tags available. report-status ------------- -The upload-pack process can receive a 'report-status' capability, +The receive-pack process can receive a 'report-status' capability, which tells it that the client wants a report of what happened after a packfile upload and reference update. If the pushing client requests this capability, after unpacking and updating references the server @@ -185,3 +234,44 @@ it is capable of accepting a zero-id value as the target value of a reference update. It is not sent back by the client, it simply informs the client that it can be sent zero-id values to delete references. + +quiet +----- + +If the receive-pack server advertises the 'quiet' capability, it is +capable of silencing human-readable progress output which otherwise may +be shown when processing the received pack. A send-pack client should +respond with the 'quiet' capability to suppress server-side progress +reporting if the local progress reporting is also being suppressed +(e.g., via `push -q`, or if stderr does not go to a tty). + +atomic +------ + +If the server sends the 'atomic' capability it is capable of accepting +atomic pushes. If the pushing client requests this capability, the server +will update the refs in one atomic transaction. Either all refs are +updated or none. + +allow-tip-sha1-in-want +---------------------- + +If the upload-pack server advertises this capability, fetch-pack may +send "want" lines with SHA-1s that exist at the server but are not +advertised by upload-pack. + +allow-reachable-sha1-in-want +---------------------------- + +If the upload-pack server advertises this capability, fetch-pack may +send "want" lines with SHA-1s that exist at the server but are not +advertised by upload-pack. + +push-cert=<nonce> +----------------- + +The receive-pack server that advertises this capability is willing +to accept a signed push certificate, and asks the <nonce> to be +included in the push certificate. A send-pack client MUST NOT +send a push-cert packet unless the receive-pack server advertises +this capability. |