Struct git_pack::index::File[−][src]

pub struct File { /* fields omitted */ }

Expand description

A representation of a pack index file

Implementations

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impl File

Instantiation

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pub fn at(path: impl AsRef<Path>) -> Result<File, Error>

Open the pack index file at the given path.

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impl File

Iteration and access

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pub fn oid_at_index(&self, index: u32) -> &oid

Returns 20 bytes sha1 at the given index in our list of (sorted) sha1 hashes. The index ranges from 0 to self.num_objects()

pub fn pack_offset_at_index(&self, index: u32) -> u64

Returns the offset into our pack data file at which to start reading the object at index.

pub fn crc32_at_index(&self, index: u32) -> Option<u32>

Returns the CRC32 of the object at the given index.

Note: These are always present for index version 2 or higher.

pub fn lookup(&self, id: impl AsRef<oid>) -> Option<u32>

Returns the index of the given SHA1 for use with the oid_at_index(), pack_offset_at_index() or crc32_at_index().

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pub fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = Entry> + 'a>

An iterator over all Entries of this index file.

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pub fn sorted_offsets(&self) -> Vec<u64>ⓘ
Notable traits for Vec<u8, A>
`impl<A> Write for Vec<u8, A> where A: Allocator,`

Return a vector of ascending offsets into our respective pack data file.

Useful to control an iteration over all pack entries in a cache-friendly way.

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impl File

Traversal with index

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pub fn traverse_with_index<P, Processor, E>(
 &self,
 check: SafetyCheck,
 thread_limit: Option<usize>,
 new_processor: impl Fn() -> Processor + Send + Clone,
 progress: P,
 pack: &File,
 should_interrupt: Arc<AtomicBool>
) -> Result<(ObjectId, Outcome, P), Error<E>> where
 P: Progress,
 Processor: FnMut(Kind, &[u8 ], &Entry, &mut <::SubProgress as Progress>::SubProgress) -> Result<(), E>,
 E: Error + Send + Sync + 'static,

Iterate through all decoded objects in the given pack and handle them with a Processor, using an index to reduce waste at the cost of memory.

For more details, see the documentation on the traverse() method.

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impl File

Verify and validate the content of the index file

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pub fn traverse_with_lookup<P, C, Processor, E>(
 &self,
 new_processor: impl Fn() -> Processor + Send + Clone,
 new_cache: impl Fn() -> C + Send + Clone,
 progress: P,
 pack: &File,
 _: Options
) -> Result<(ObjectId, Outcome, P), Error<E>> where
 P: Progress,
 C: DecodeEntry,
 E: Error + Send + Sync + 'static,
 Processor: FnMut(Kind, &[u8 ], &Entry, &mut <::SubProgress as Progress>::SubProgress) -> Result<(), E>,

Iterate through all decoded objects in the given pack and handle them with a Processor using a cache to reduce the amount of waste while decoding objects.

For more details, see the documentation on the traverse() method.

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impl File

Traversal of pack data files using an index file

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pub fn traverse<P, C, Processor, E>(
 &self,
 pack: &File,
 progress: Option,
 new_processor: impl Fn() -> Processor + Send + Clone,
 new_cache: impl Fn() -> C + Send + Clone,
 _: Options
) -> Result<(ObjectId, Outcome, Option), Error<E>> where
 P: Progress,
 C: DecodeEntry,
 E: Error + Send + Sync + 'static,
 Processor: FnMut(Kind, &[u8 ], &Entry, &mut DoOrDiscard<<::SubProgress as Progress>::SubProgress>) -> Result<(), E>,

Iterate through all decoded objects in the given pack and handle them with a Processor. The return value is (pack-checksum, Outcome, progress), thus the pack traversal will always verify the whole packs checksum to assure it was correct. In case of bit-rod, the operation will abort early without verifying all objects using the interrupt mechanism mechanism.

Algorithms

Using the Options::algorithm field one can chose between two algorithms providing different tradeoffs. Both invoke new_processor() to create functions receiving decoded objects, their object kind, index entry and a progress instance to provide progress information.

Algorithm::DeltaTreeLookup builds an index to avoid any unnecessary computation while resolving objects, avoiding the need for a cache entirely, rendering new_cache() unused. One could also call traverse_with_index() directly.
Algorithm::Lookup uses a cache created by new_cache() to avoid having to re-compute all bases of a delta-chain while decoding objects. One could also call traverse_with_lookup() directly.

Use thread_limit to further control parallelism and check to define how much the passed objects shall be verified beforehand.

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impl File

Verify and validate the content of the index file

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pub fn index_checksum(&self) -> ObjectId

Returns the trailing hash stored at the end of this index file.

It’s a hash over all bytes of the index.

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pub fn pack_checksum(&self) -> ObjectId

Returns the hash of the pack data file that this index file corresponds to.

It should crate::data::File::checksum() of the corresponding pack data file.

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pub fn verify_checksum(
 &self,
 progress: impl Progress,
 should_interrupt: &AtomicBool
) -> Result<ObjectId, Error>

Validate that our index_checksum() matches the actual contents of this index file, and return it if it does.

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pub fn verify_integrity<C, P>(
 &self,
 pack: Option<(&File, Mode, Algorithm, impl Fn() -> C + Send + Clone )>,
 thread_limit: Option<usize>,
 progress: Option,
 should_interrupt: Arc<AtomicBool>
) -> Result<(ObjectId, Option<Outcome>, Option), Error<Error>> where
 P: Progress,
 C: DecodeEntry,

The most thorough validation of integrity of both index file and the corresponding pack data file, if provided. Returns the checksum of the index file, the traversal outcome and the given progress if the integrity check is successful.

If pack is provided, it is expected (and validated to be) the pack belonging to this index. It will be used to validate internal integrity of the pack before checking each objects integrity is indeed as advertised via its SHA1 as stored in this index, as well as the CRC32 hash. The last member of the Option is a function returning an implementation of crate::cache::DecodeEntry to be used if the index::traverse::Algorithm is Lookup. To set this to None, use None::<(_, _, _, fn() -> crate::cache::Never)>.

The thread_limit optionally specifies the amount of threads to be used for the pack traversal. make_cache is only used in case a pack is specified, use existing implementations in the crate::cache module.

Tradeoffs

The given progress is inevitably consumed if there is an error, which is a tradeoff chosen to easily allow using ? in the error case.

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impl File

Various ways of writing an index file from pack entries

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pub fn write_data_iter_to_stream<F, F2>(
 kind: Version,
 make_resolver: F,
 entries: impl Iterator<Item = Result<Entry, Error>>,
 thread_limit: Option<usize>,
 root_progress: impl Progress,
 out: impl Write,
 should_interrupt: &AtomicBool
) -> Result<Outcome, Error> where
 F: FnOnce() -> Result<F2>,
 F2: for<'r> Fn(EntryRange, &'r mut Vec<u8>) -> Option<()> + Send + Clone,

Write information about entries as obtained from a pack data file into a pack index file via the out stream. The resolver produced by make_resolver must resolve pack entries from the same pack data file that produced the entries iterator.

kind is the version of pack index to produce, use crate::index::Version::default() if in doubt. tread_limit is used for a parallel tree traversal for obtaining object hashes with optimal performance. root_progress is the top-level progress to stay informed about the progress of this potentially long-running computation.

Remarks

neither in-pack nor out-of-pack Ref Deltas are supported here, these must have been resolved beforehand.
make_resolver() will only be called after the iterator stopped returning elements and produces a function that provides all bytes belonging to a pack entry writing them to the given mutable output Vec. It should return None if the entry cannot be resolved from the pack that produced the entries iterator, causing the write operation to fail.

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