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use std::ops::Deref;
use git_hash::oid;
use super::find::Error;
use crate::{
find::Header,
store::{find::error::DeltaBaseRecursion, handle, load_index},
};
impl<S> super::Handle<S>
where
S: Deref<Target = super::Store> + Clone,
{
fn try_header_inner<'b>(
&'b self,
mut id: &'b git_hash::oid,
snapshot: &mut load_index::Snapshot,
recursion: Option<DeltaBaseRecursion<'_>>,
) -> Result<Option<Header>, Error> {
if let Some(r) = recursion {
if r.depth >= self.max_recursion_depth {
return Err(Error::DeltaBaseRecursionLimit {
max_depth: self.max_recursion_depth,
id: r.original_id.to_owned(),
});
}
} else if !self.ignore_replacements {
if let Ok(pos) = self
.store
.replacements
.binary_search_by(|(map_this, _)| map_this.as_ref().cmp(id))
{
id = self.store.replacements[pos].1.as_ref();
}
}
'outer: loop {
{
let marker = snapshot.marker;
for (idx, index) in snapshot.indices.iter_mut().enumerate() {
if let Some(handle::index_lookup::Outcome {
object_index: handle::IndexForObjectInPack { pack_id, pack_offset },
index_file,
pack: possibly_pack,
}) = index.lookup(id)
{
let pack = match possibly_pack {
Some(pack) => pack,
None => match self.store.load_pack(pack_id, marker)? {
Some(pack) => {
*possibly_pack = Some(pack);
possibly_pack.as_deref().expect("just put it in")
}
None => {
// The pack wasn't available anymore so we are supposed to try another round with a fresh index
match self.store.load_one_index(self.refresh, snapshot.marker)? {
Some(new_snapshot) => {
*snapshot = new_snapshot;
self.clear_cache();
continue 'outer;
}
None => {
// nothing new in the index, kind of unexpected to not have a pack but to also
// to have no new index yet. We set the new index before removing any slots, so
// this should be observable.
return Ok(None);
}
}
}
},
};
let entry = pack.entry(pack_offset);
let res = match pack.decode_header(entry, |id| {
index_file.pack_offset_by_id(id).map(|pack_offset| {
git_pack::data::decode::header::ResolvedBase::InPack(pack.entry(pack_offset))
})
}) {
Ok(header) => Ok(header.into()),
Err(git_pack::data::decode::Error::DeltaBaseUnresolved(base_id)) => {
// Only with multi-pack indices it's allowed to jump to refer to other packs within this
// multi-pack. Otherwise this would constitute a thin pack which is only allowed in transit.
// However, if we somehow end up with that, we will resolve it safely, even though we could
// avoid handling this case and error instead.
let hdr = self
.try_header_inner(
&base_id,
snapshot,
recursion
.map(|r| r.inc_depth())
.or_else(|| DeltaBaseRecursion::new(id).into()),
)
.map_err(|err| Error::DeltaBaseLookup {
err: Box::new(err),
base_id,
id: id.to_owned(),
})?
.ok_or_else(|| Error::DeltaBaseMissing {
base_id,
id: id.to_owned(),
})?;
let handle::index_lookup::Outcome {
object_index:
handle::IndexForObjectInPack {
pack_id: _,
pack_offset,
},
index_file,
pack: possibly_pack,
} = match snapshot.indices[idx].lookup(id) {
Some(res) => res,
None => {
let mut out = None;
for index in snapshot.indices.iter_mut() {
out = index.lookup(id);
if out.is_some() {
break;
}
}
out.unwrap_or_else(|| {
panic!("could not find object {id} in any index after looking up one of its base objects {base_id}")
})
}
};
let pack = possibly_pack
.as_ref()
.expect("pack to still be available like just now");
let entry = pack.entry(pack_offset);
pack.decode_header(entry, |id| {
index_file
.pack_offset_by_id(id)
.map(|pack_offset| {
git_pack::data::decode::header::ResolvedBase::InPack(
pack.entry(pack_offset),
)
})
.or_else(|| {
(id == base_id).then(|| {
git_pack::data::decode::header::ResolvedBase::OutOfPack {
kind: hdr.kind(),
num_deltas: hdr.num_deltas(),
}
})
})
})
.map(Into::into)
}
Err(err) => Err(err),
}?;
if idx != 0 {
snapshot.indices.swap(0, idx);
}
return Ok(Some(res));
}
}
}
for lodb in snapshot.loose_dbs.iter() {
// TODO: remove this double-lookup once the borrow checker allows it.
if lodb.contains(id) {
return lodb.try_header(id).map(|opt| opt.map(Into::into)).map_err(Into::into);
}
}
match self.store.load_one_index(self.refresh, snapshot.marker)? {
Some(new_snapshot) => {
*snapshot = new_snapshot;
self.clear_cache();
}
None => return Ok(None),
}
}
}
}
impl<S> crate::Header for super::Handle<S>
where
S: Deref<Target = super::Store> + Clone,
{
type Error = Error;
fn try_header(&self, id: impl AsRef<oid>) -> Result<Option<Header>, Self::Error> {
let id = id.as_ref();
let mut snapshot = self.snapshot.borrow_mut();
self.try_header_inner(id, &mut snapshot, None)
}
}