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use std::sync::atomic::AtomicBool;
use git_odb::FindExt;
use git_protocol::transport::client::Transport;
use crate::{
remote,
remote::{
connection::fetch::config,
fetch,
fetch::{negotiate, refs, Error, Outcome, Prepare, ProgressId, RefLogMessage, Status},
},
Progress,
};
impl<'remote, 'repo, T, P> Prepare<'remote, 'repo, T, P>
where
T: Transport,
P: Progress,
P::SubProgress: 'static,
{
/// Receive the pack and perform the operation as configured by git via `git-config` or overridden by various builder methods.
/// Return `Ok(None)` if there was nothing to do because all remote refs are at the same state as they are locally, or `Ok(Some(outcome))`
/// to inform about all the changes that were made.
///
/// ### Negotiation
///
/// "fetch.negotiationAlgorithm" describes algorithms `git` uses currently, with the default being `consecutive` and `skipping` being
/// experimented with. We currently implement something we could call 'naive' which works for now.
///
/// ### Pack `.keep` files
///
/// That packs that are freshly written to the object database are vulnerable to garbage collection for the brief time that it takes between
/// them being placed and the respective references to be written to disk which binds their objects to the commit graph, making them reachable.
///
/// To circumvent this issue, a `.keep` file is created before any pack related file (i.e. `.pack` or `.idx`) is written, which indicates the
/// garbage collector (like `git maintenance`, `git gc`) to leave the corresponding pack file alone.
///
/// If there were any ref updates or the received pack was empty, the `.keep` file will be deleted automatically leaving in its place at
/// `write_pack_bundle.keep_path` a `None`.
/// However, if no ref-update happened the path will still be present in `write_pack_bundle.keep_path` and is expected to be handled by the caller.
/// A known application for this behaviour is in `remote-helper` implementations which should send this path via `lock <path>` to stdout
/// to inform git about the file that it will remove once it updated the refs accordingly.
///
/// ### Deviation
///
/// When **updating refs**, the `git-fetch` docs state that the following:
///
/// > Unlike when pushing with git-push, any updates outside of refs/{tags,heads}/* will be accepted without + in the refspec (or --force), whether that’s swapping e.g. a tree object for a blob, or a commit for another commit that’s doesn’t have the previous commit as an ancestor etc.
///
/// We explicitly don't special case those refs and expect the user to take control. Note that by its nature,
/// force only applies to refs pointing to commits and if they don't, they will be updated either way in our
/// implementation as well.
///
/// ### Async Mode Shortcoming
///
/// Currently the entire process of resolving a pack is blocking the executor. This can be fixed using the `blocking` crate, but it
/// didn't seem worth the tradeoff of having more complex code.
///
/// ### Configuration
///
/// - `gitoxide.userAgent` is read to obtain the application user agent for git servers and for HTTP servers as well.
///
#[git_protocol::maybe_async::maybe_async]
pub async fn receive(mut self, should_interrupt: &AtomicBool) -> Result<Outcome, Error> {
let mut con = self.con.take().expect("receive() can only be called once");
let handshake = &self.ref_map.handshake;
let protocol_version = handshake.server_protocol_version;
let fetch = git_protocol::Command::Fetch;
let progress = &mut con.progress;
let repo = con.remote.repo;
let fetch_features = {
let mut f = fetch.default_features(protocol_version, &handshake.capabilities);
f.push(repo.config.user_agent_tuple());
f
};
git_protocol::fetch::Response::check_required_features(protocol_version, &fetch_features)?;
let sideband_all = fetch_features.iter().any(|(n, _)| *n == "sideband-all");
let mut arguments = git_protocol::fetch::Arguments::new(protocol_version, fetch_features);
if matches!(con.remote.fetch_tags, crate::remote::fetch::Tags::Included) {
if !arguments.can_use_include_tag() {
unimplemented!("we expect servers to support 'include-tag', otherwise we have to implement another pass to fetch attached tags separately");
}
arguments.use_include_tag();
}
let mut previous_response = None::<git_protocol::fetch::Response>;
let mut round = 1;
if self.ref_map.object_hash != repo.object_hash() {
return Err(Error::IncompatibleObjectHash {
local: repo.object_hash(),
remote: self.ref_map.object_hash,
});
}
let reader = 'negotiation: loop {
progress.step();
progress.set_name(format!("negotiate (round {round})"));
let is_done = match negotiate::one_round(
negotiate::Algorithm::Naive,
round,
repo,
&self.ref_map,
con.remote.fetch_tags,
&mut arguments,
previous_response.as_ref(),
) {
Ok(_) if arguments.is_empty() => {
git_protocol::indicate_end_of_interaction(&mut con.transport).await.ok();
let update_refs = refs::update(
repo,
self.reflog_message
.take()
.unwrap_or_else(|| RefLogMessage::Prefixed { action: "fetch".into() }),
&self.ref_map.mappings,
con.remote.refspecs(remote::Direction::Fetch),
&self.ref_map.extra_refspecs,
con.remote.fetch_tags,
self.dry_run,
self.write_packed_refs,
)?;
return Ok(Outcome {
ref_map: std::mem::take(&mut self.ref_map),
status: Status::NoPackReceived { update_refs },
});
}
Ok(is_done) => is_done,
Err(err) => {
git_protocol::indicate_end_of_interaction(&mut con.transport).await.ok();
return Err(err.into());
}
};
round += 1;
let mut reader = arguments.send(&mut con.transport, is_done).await?;
if sideband_all {
setup_remote_progress(progress, &mut reader);
}
let response = git_protocol::fetch::Response::from_line_reader(protocol_version, &mut reader).await?;
if response.has_pack() {
progress.step();
progress.set_name("receiving pack");
if !sideband_all {
setup_remote_progress(progress, &mut reader);
}
break 'negotiation reader;
} else {
previous_response = Some(response);
}
};
let options = git_pack::bundle::write::Options {
thread_limit: config::index_threads(repo)?,
index_version: config::pack_index_version(repo)?,
iteration_mode: git_pack::data::input::Mode::Verify,
object_hash: con.remote.repo.object_hash(),
};
let mut write_pack_bundle = if matches!(self.dry_run, fetch::DryRun::No) {
Some(git_pack::Bundle::write_to_directory(
#[cfg(feature = "async-network-client")]
{
git_protocol::futures_lite::io::BlockOn::new(reader)
},
#[cfg(not(feature = "async-network-client"))]
{
reader
},
Some(repo.objects.store_ref().path().join("pack")),
con.progress,
should_interrupt,
Some(Box::new({
let repo = repo.clone();
move |oid, buf| repo.objects.find(oid, buf).ok()
})),
options,
)?)
} else {
drop(reader);
None
};
if matches!(protocol_version, git_protocol::transport::Protocol::V2) {
git_protocol::indicate_end_of_interaction(&mut con.transport).await.ok();
}
let update_refs = refs::update(
repo,
self.reflog_message
.take()
.unwrap_or_else(|| RefLogMessage::Prefixed { action: "fetch".into() }),
&self.ref_map.mappings,
con.remote.refspecs(remote::Direction::Fetch),
&self.ref_map.extra_refspecs,
con.remote.fetch_tags,
self.dry_run,
self.write_packed_refs,
)?;
if let Some(bundle) = write_pack_bundle.as_mut() {
if !update_refs.edits.is_empty() || bundle.index.num_objects == 0 {
if let Some(path) = bundle.keep_path.take() {
std::fs::remove_file(&path).map_err(|err| Error::RemovePackKeepFile { path, source: err })?;
}
}
}
Ok(Outcome {
ref_map: std::mem::take(&mut self.ref_map),
status: match write_pack_bundle {
Some(write_pack_bundle) => Status::Change {
write_pack_bundle,
update_refs,
},
None => Status::DryRun { update_refs },
},
})
}
}
fn setup_remote_progress<P>(
progress: &mut P,
reader: &mut Box<dyn git_protocol::transport::client::ExtendedBufRead + Unpin + '_>,
) where
P: Progress,
P::SubProgress: 'static,
{
use git_protocol::transport::client::ExtendedBufRead;
reader.set_progress_handler(Some(Box::new({
let mut remote_progress = progress.add_child_with_id("remote", ProgressId::RemoteProgress.into());
move |is_err: bool, data: &[u8]| {
git_protocol::RemoteProgress::translate_to_progress(is_err, data, &mut remote_progress)
}
}) as git_protocol::transport::client::HandleProgress));
}