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use crate::data;
/// Describe how object can be located in an object store with built-in facilities to supports packs specifically.
///
/// ## Notes
///
/// Locate effectively needs [generic associated types][issue] to allow a trait for the returned object type.
/// Until then, we will have to make due with explicit types and give them the potentially added features we want.
///
/// [issue]: https://github.com/rust-lang/rust/issues/44265
pub trait Find {
/// The error returned by [`find()`][Find::find()]
type Error: std::error::Error + 'static;
/// Find an object matching `id` in the database while placing its raw, undecoded data into `buffer`.
/// A `pack_cache` can be used to speed up subsequent lookups, set it to [`crate::cache::Never`] if the
/// workload isn't suitable for caching.
///
/// Returns `Some` object if it was present in the database, or the error that occurred during lookup or object
/// retrieval.
fn find<'a>(
&self,
id: impl AsRef<git_hash::oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<Option<data::Object<'a>>, Self::Error>;
/// Find the packs location where an object with `id` can be found in the database, or `None` if there is no pack
/// holding the object.
///
/// _Note_ that the object database may have no notion of packs and thus always returns `None`.
fn location_by_oid(&self, id: impl AsRef<git_hash::oid>, buf: &mut Vec<u8>) -> Option<crate::bundle::Location>;
/// Find the bundle matching `pack_id`, or `None` if there is no such pack.
///
/// _Note_ that the object database may have no notion of packs and thus always returns `None`.
fn bundle_by_pack_id(&self, pack_id: u32) -> Option<&crate::Bundle>;
/// Return the [`Entry`] for `location` if it is backed by a pack.
///
/// Note that this is only in the interest of avoiding duplicate work during pack generation.
/// Pack locations can be obtained from a [`data::Object`].
///
/// # Notes
///
/// Custom implementations might be interested in providing their own meta-data with `object`,
/// which currently isn't possible as the `Locate` trait requires GATs to work like that.
fn entry_by_location(&self, location: &crate::bundle::Location) -> Option<Entry<'_>>;
}
mod ext {
use crate::{data, find};
use git_object::{immutable, Kind};
macro_rules! make_obj_lookup {
($method:ident, $object_variant:path, $object_kind:path, $object_type:ty) => {
/// Like [`find_existing(…)`][Self::find_existing()], but flattens the `Result<Option<_>>` into a single `Result` making a non-existing object an error
/// while returning the desired object type.
fn $method<'a>(
&self,
id: impl AsRef<git_hash::oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<$object_type, find::existing_object::Error<Self::Error>> {
let id = id.as_ref();
self.find(id, buffer, pack_cache)
.map_err(find::existing_object::Error::Find)?
.ok_or_else(|| find::existing_object::Error::NotFound {
oid: id.as_ref().to_owned(),
})
.and_then(|o| o.decode().map_err(find::existing_object::Error::Decode))
.and_then(|o| match o {
$object_variant(o) => return Ok(o),
_other => Err(find::existing_object::Error::ObjectKind {
expected: $object_kind,
}),
})
}
};
}
macro_rules! make_iter_lookup {
($method:ident, $object_kind:path, $object_type:ty, $into_iter:tt) => {
/// Like [`find_existing(…)`][Self::find_existing()], but flattens the `Result<Option<_>>` into a single `Result` making a non-existing object an error
/// while returning the desired iterator type.
fn $method<'a>(
&self,
id: impl AsRef<git_hash::oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<$object_type, find::existing_iter::Error<Self::Error>> {
let id = id.as_ref();
self.find(id, buffer, pack_cache)
.map_err(find::existing_iter::Error::Find)?
.ok_or_else(|| find::existing_iter::Error::NotFound {
oid: id.as_ref().to_owned(),
})
.and_then(|o| {
o.$into_iter()
.ok_or_else(|| find::existing_iter::Error::ObjectKind {
expected: $object_kind,
})
})
}
};
}
/// An extension trait with convenience functions.
pub trait FindExt: super::Find {
/// Like [`find(…)`][super::Find::find()], but flattens the `Result<Option<_>>` into a single `Result` making a non-existing object an error.
fn find_existing<'a>(
&self,
id: impl AsRef<git_hash::oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<data::Object<'a>, find::existing::Error<Self::Error>> {
let id = id.as_ref();
self.find(id, buffer, pack_cache)
.map_err(find::existing::Error::Find)?
.ok_or_else(|| find::existing::Error::NotFound {
oid: id.as_ref().to_owned(),
})
}
make_obj_lookup!(
find_existing_commit,
immutable::Object::Commit,
Kind::Commit,
immutable::Commit<'a>
);
make_obj_lookup!(
find_existing_tree,
immutable::Object::Tree,
Kind::Tree,
immutable::Tree<'a>
);
make_obj_lookup!(find_existing_tag, immutable::Object::Tag, Kind::Tag, immutable::Tag<'a>);
make_obj_lookup!(
find_existing_blob,
immutable::Object::Blob,
Kind::Blob,
immutable::Blob<'a>
);
make_iter_lookup!(
find_existing_commit_iter,
Kind::Blob,
immutable::CommitIter<'a>,
into_commit_iter
);
make_iter_lookup!(
find_existing_tree_iter,
Kind::Tree,
immutable::TreeIter<'a>,
into_tree_iter
);
}
impl<T: super::Find> FindExt for T {}
}
pub use ext::FindExt;
///
pub mod existing {
use git_hash::ObjectId;
/// The error returned by the [`find_existing(…)`][crate::FindExt::find_existing()] trait methods.
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error<T: std::error::Error + 'static> {
#[error(transparent)]
Find(T),
#[error("An object with id {} could not be found", .oid)]
NotFound { oid: ObjectId },
}
}
///
pub mod existing_object {
use git_hash::ObjectId;
use git_object::immutable;
/// The error returned by the various [`find_existing_*`][crate::FindExt::find_existing_commit()] trait methods.
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error<T: std::error::Error + 'static> {
#[error(transparent)]
Find(T),
#[error(transparent)]
Decode(immutable::object::decode::Error),
#[error("An object with id {} could not be found", .oid)]
NotFound { oid: ObjectId },
#[error("Expected object of kind {} something else", .expected)]
ObjectKind { expected: git_object::Kind },
}
}
///
pub mod existing_iter {
use git_hash::ObjectId;
/// The error returned by the various [`find_existing_*`][crate::FindExt::find_existing_commit()] trait methods.
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error<T: std::error::Error + 'static> {
#[error(transparent)]
Find(T),
#[error("An object with id {} could not be found", .oid)]
NotFound { oid: ObjectId },
#[error("Expected object of kind {} something else", .expected)]
ObjectKind { expected: git_object::Kind },
}
}
/// An Entry in a pack providing access to its data.
///
/// Its commonly retrieved by reading from a pack index file followed by a read from a pack data file.
#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
#[allow(missing_docs)]
pub struct Entry<'a> {
/// The pack-data encoded bytes of the pack data entry as present in the pack file, including the header followed by compressed data.
pub data: &'a [u8],
/// The crc32 hash over the entirety of `data`, or None if the pack file format doesn't support it yet.
pub crc32: Option<u32>,
/// The version of the pack file containing `data`
pub version: crate::data::Version,
}
mod find_impls {
use crate::bundle::Location;
use crate::{data::Object, find::Entry, Bundle};
use git_hash::oid;
use std::ops::Deref;
impl<T> super::Find for std::sync::Arc<T>
where
T: super::Find,
{
type Error = T::Error;
fn find<'a>(
&self,
id: impl AsRef<oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<Option<Object<'a>>, Self::Error> {
self.deref().find(id, buffer, pack_cache)
}
fn location_by_oid(&self, id: impl AsRef<oid>, buf: &mut Vec<u8>) -> Option<Location> {
self.deref().location_by_oid(id, buf)
}
fn bundle_by_pack_id(&self, pack_id: u32) -> Option<&Bundle> {
self.deref().bundle_by_pack_id(pack_id)
}
fn entry_by_location(&self, object: &crate::bundle::Location) -> Option<Entry<'_>> {
self.deref().entry_by_location(object)
}
}
impl<T> super::Find for Box<T>
where
T: super::Find,
{
type Error = T::Error;
fn find<'a>(
&self,
id: impl AsRef<oid>,
buffer: &'a mut Vec<u8>,
pack_cache: &mut impl crate::cache::DecodeEntry,
) -> Result<Option<Object<'a>>, Self::Error> {
self.deref().find(id, buffer, pack_cache)
}
fn location_by_oid(&self, id: impl AsRef<oid>, buf: &mut Vec<u8>) -> Option<Location> {
self.deref().location_by_oid(id, buf)
}
fn bundle_by_pack_id(&self, pack_id: u32) -> Option<&Bundle> {
self.deref().bundle_by_pack_id(pack_id)
}
fn entry_by_location(&self, location: &crate::bundle::Location) -> Option<Entry<'_>> {
self.deref().entry_by_location(location)
}
}
}