…into async-io, as usual.
Showing the changes to git-protocol/src/fetch/delegate.rs (1 of 12 files). Show all
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| 1 | use crate::fetch::{Arguments, Ref, Response}; | ||
| 2 | use bstr::BString; | ||
| 3 | use git_features::progress::Progress; | ||
| 4 | use git_transport::client::Capabilities; | ||
| 5 | use std::io; | ||
| 6 | |||
| 7 | /// Defines what to do next after certain [`Delegate`] operations. | ||
| 8 | #[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)] | ||
| 9 | pub enum Action { | ||
| 10 | /// Continue the typical flow of operations in this flow. | ||
| 11 | Continue, | ||
| 12 | /// Close the connection without making any further requests. | ||
| 13 | Close, | ||
| 14 | } | ||
| 15 | |||
| 16 | /// The protocol delegate is the bare minimal interface needed to fully control the [`fetch`][crate::fetch()] operation. | ||
| 17 | /// | ||
| 18 | /// Implementations of this trait are controlled by code with intricate knowledge about how fetching works in protocol version V1 and V2, | ||
| 19 | /// so you don't have to. | ||
| 20 | /// Everything is tucked away behind type-safety so 'nothing can go wrong'©. Runtime assertions assure invalid | ||
| 21 | /// features or arguments don't make it to the server in the first place. | ||
| 22 | /// Please note that this trait mostly corresponds to what V2 would look like, even though V1 is supported as well. | ||
| 23 | pub trait Delegate { | ||
| 24 | /// Called before invoking 'ls-refs' on the server to allow providing it with additional `arguments` and to enable `features`. | ||
| 25 | /// | ||
| 26 | /// Note that some arguments are preset based on typical use, and `features` are preset to maximize options. | ||
| 27 | /// The `server` capabilities can be used to see which additional capabilities the server supports as per the handshake which happened prior. | ||
| 28 | /// Note that this is called only if we are using protocol version 2. | ||
| 29 | fn prepare_ls_refs( | ||
| 30 | &mut self, | ||
| 31 | _server: &Capabilities, | ||
| 32 | _arguments: &mut Vec<BString>, | ||
| 33 | _features: &mut Vec<(&str, Option<&str>)>, | ||
| 34 | ) { | ||
| 35 | } | ||
| 36 | |||
| 37 | /// Called before invoking the 'fetch' interaction with `features` pre-filled for typical use | ||
| 38 | /// and to maximize capabilities to allow aborting an interaction early. | ||
| 39 | /// | ||
| 40 | /// `refs` is a list of known references on the remote based on the handshake or a prior call to ls_refs. | ||
| 41 | /// These can be used to abort early in case the refs are already known here. | ||
| 42 | /// | ||
| 43 | /// As there will be another call allowing to post arguments conveniently in the correct format, i.e. `want hex-oid`, | ||
| 44 | /// there is no way to set arguments at this time. | ||
| 45 | /// | ||
| 46 | /// `version` is the actually supported version as reported by the server, which is relevant in case the server requested a downgrade. | ||
| 47 | /// `server` capabilities is a list of features the server supports for your information, along with enabled `features` that the server knows about. | ||
| 48 | fn prepare_fetch( | ||
| 49 | &mut self, | ||
| 50 | _version: git_transport::Protocol, | ||
| 51 | _server: &Capabilities, | ||
| 52 | _features: &mut Vec<(&str, Option<&str>)>, | ||
| 53 | _refs: &[Ref], | ||
| 54 | ) -> Action { | ||
| 55 | Action::Continue | ||
| 56 | } | ||
| 57 | |||
| 58 | /// A method called repeatedly to negotiate the objects to receive in [`receive_pack(…)`][Delegate::receive_pack()]. | ||
| 59 | /// | ||
| 60 | /// The first call has `previous` set to `None` as there was no previous response. Every call that follows `previous` | ||
| 61 | /// will be set to `Some`. | ||
| 62 | /// | ||
| 63 | /// ### If `previous` is `None`… | ||
| 64 | /// | ||
| 65 | /// Given a list of `arguments` to populate with wants, shallows, filters and other contextual information to be | ||
| 66 | /// sent to the server. This method is called once. | ||
| 67 | /// Send the objects you `have` have afterwards based on the tips of your refs, in preparation to walk down their parents | ||
| 68 | /// with each call to `negotiate` to find the common base(s). | ||
| 69 | /// | ||
| 70 | /// Note that you should not `want` and object that you already have. | ||
| 71 | /// `refs` are the the tips of on the server side, effectively the latest objects _they_ have. | ||
| 72 | /// | ||
| 73 | /// Return `Action::Close` if you know that there are no `haves` on your end to allow the server to send all of its objects | ||
| 74 | /// as is the case during initial clones. | ||
| 75 | /// | ||
| 76 | /// ### If `previous` is `Some`… | ||
| 77 | /// | ||
| 78 | /// Populate `arguments` with the objects you `have` starting from the tips of _your_ refs, taking into consideration | ||
| 79 | /// the `previous` response of the server to see which objects they acknowledged to have. You have to maintain | ||
| 80 | /// enough state to be able to walk down from your tips on each call, if they are not in common, and keep setting `have` | ||
| 81 | /// for those which are in common if that helps teaching the server about our state and to acknowledge their existence on _their_ end. | ||
| 82 | /// This method is called until the other side signals they are ready to send a pack. | ||
| 83 | /// Return `Action::Close` if you want to give up before finding a common base. This can happen if the remote repository | ||
| 84 | /// has radically changed so there are no bases, or they are very far in the past, causing all objects to be sent. | ||
| 85 | fn negotiate(&mut self, refs: &[Ref], arguments: &mut Arguments, previous: Option<&Response>) -> Action; | ||
| 86 | |||
| 87 | /// Receive a pack provided from the given `input`. | ||
| 88 | /// | ||
| 89 | /// Use `progress` to emit your own progress messages when decoding the pack. | ||
| 90 | /// | ||
| 91 | /// `refs` of the remote side are provided for convenience, along with the parsed `previous` response in case you want | ||
| 92 | /// to check additional acks. | ||
| 93 | fn receive_pack( | ||
| 94 | &mut self, | ||
| 95 | input: impl io::BufRead, | ||
| 96 | progress: impl Progress, | ||
| 97 | refs: &[Ref], | ||
| 98 | previous: &Response, | ||
| 99 | ) -> io::Result<()>; | ||
| 100 | } | ||