Trait Find

pub trait Find {
    // Required methods
    fn contains(&self, id: &oid) -> bool;
    fn try_find_cached<'a>(
        &self,
        id: &oid,
        buffer: &'a mut Vec<u8>,
        pack_cache: &mut dyn DecodeEntry,
    ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>;
    fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>;
    fn pack_offsets_and_oid(
        &self,
        pack_id: u32,
    ) -> Option<Vec<(Offset, ObjectId)>>;
    fn entry_by_location(&self, location: &Location) -> Option<Entry>;

    // Provided method
    fn try_find<'a>(
        &self,
        id: &oid,
        buffer: &'a mut Vec<u8>,
    ) -> Result<Option<(Data<'a>, Option<Location>)>, Error> { ... }
}

Describe how object can be located in an object store with built-in facilities to supports packs specifically.

Notes

Find effectively needs generic associated types 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.

Furthermore, despite this trait being in gix-pack, it leaks knowledge about objects potentially not being packed. This is a necessary trade-off to allow this trait to live in gix-pack where it is used in functions to create a pack.

Required Methods

fn contains(&self, id: &oid) -> bool

Returns true if the object exists in the database.

fn try_find_cached<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, pack_cache: &mut dyn DecodeEntry, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

Like Find::try_find(), but with support for controlling the pack cache. 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 data>, <pack location if packed>)) if it was present in the database, or the error that occurred during lookup or object retrieval.

fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>

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 this is always None if the object isn’t packed even though it exists as loose object.

fn pack_offsets_and_oid(&self, pack_id: u32) -> Option<Vec<(Offset, ObjectId)>>

Obtain a vector of all offsets, in index order, along with their object id.

fn entry_by_location(&self, location: &Location) -> Option<Entry>

Return the find::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 Find::try_find().

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.

Provided Methods

fn try_find<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

Find an object matching id in the database while placing its raw, decoded 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 data>, <pack location if packed>)) if it was present in the database, or the error that occurred during lookup or object retrieval.

Implementations on Foreign Types

impl<T> Find for &T

where T: Find,

fn contains(&self, id: &oid) -> bool

fn try_find_cached<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, pack_cache: &mut dyn DecodeEntry, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>

fn pack_offsets_and_oid(&self, pack_id: u32) -> Option<Vec<(Offset, ObjectId)>>

fn entry_by_location(&self, location: &Location) -> Option<Entry>

impl<T> Find for Box<T>

where T: Find,

fn contains(&self, id: &oid) -> bool

fn try_find_cached<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, pack_cache: &mut dyn DecodeEntry, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>

fn pack_offsets_and_oid(&self, pack_id: u32) -> Option<Vec<(Offset, ObjectId)>>

fn entry_by_location(&self, location: &Location) -> Option<Entry>

impl<T> Find for Rc<T>

where T: Find,

fn contains(&self, id: &oid) -> bool

fn try_find_cached<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, pack_cache: &mut dyn DecodeEntry, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>

fn pack_offsets_and_oid(&self, pack_id: u32) -> Option<Vec<(Offset, ObjectId)>>

fn entry_by_location(&self, location: &Location) -> Option<Entry>

impl<T> Find for Arc<T>

where T: Find,

fn contains(&self, id: &oid) -> bool

fn try_find_cached<'a>( &self, id: &oid, buffer: &'a mut Vec<u8>, pack_cache: &mut dyn DecodeEntry, ) -> Result<Option<(Data<'a>, Option<Location>)>, Error>

fn location_by_oid(&self, id: &oid, buf: &mut Vec<u8>) -> Option<Location>

fn pack_offsets_and_oid(&self, pack_id: u32) -> Option<Vec<(Offset, ObjectId)>>

fn entry_by_location(&self, object: &Location) -> Option<Entry>

Implementors