Crate gix

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This crate provides the Repository abstraction which serves as a hub into all the functionality of git.

It’s powerful and won’t sacrifice performance while still increasing convenience compared to using the sub-crates individually. Sometimes it may hide complexity under the assumption that the performance difference doesn’t matter for all but the fewest tools out there, which would be using the underlying crates directly or file an issue.

§The Trust Model

It is very simple - based on the ownership of the repository compared to the user of the current process Trust is assigned. This can be overridden as well. Further, git configuration files track their trust level per section based on and sensitive values like paths to executables or certain values will be skipped if they are from a source that isn’t fully trusted.

That way, data can safely be obtained without risking to execute untrusted executables.

Note that it’s possible to let gix act like git or git2 by setting the open::Options::bail_if_untrusted() option.

§The prelude and extensions

With use git_repository::prelude::* you should be ready to go as it pulls in various extension traits to make functionality available on objects that may use it.

The method signatures are still complex and may require various arguments for configuration and cache control.

Most extensions to existing objects provide an obj_with_extension.attach(&repo).an_easier_version_of_a_method() for simpler call signatures.

§ThreadSafe Mode

By default, the Repository isn’t Sync and thus can’t be used in certain contexts which require the Sync trait.

To help with this, convert it with .into_sync() into a ThreadSafeRepository.

§Object-Access Performance

Accessing objects quickly is the bread-and-butter of working with git, right after accessing references. Hence it’s vital to understand which cache levels exist and how to leverage them.

When accessing an object, the first cache that’s queried is a memory-capped LRU object cache, mapping their id to data and kind. It has to be specifically enabled a Repository. On miss, the object is looked up and if a pack is hit, there is a small fixed-size cache for delta-base objects.

In scenarios where the same objects are accessed multiple times, the object cache can be useful and is to be configured specifically using the object_cache_size(…) method.

Use the cache-efficiency-debug cargo feature to learn how efficient the cache actually is - it’s easy to end up with lowered performance if the cache is not hit in 50% of the time.

§Terminology

§WorkingTree and WorkTree

When reading the documentation of the canonical gix-worktree program one gets the impression work tree and working tree are used interchangeably. We use the term work tree only and try to do so consistently as its shorter and assumed to be the same.

§Plumbing Crates

To make using sub-crates and their types easier, these are re-exported into the root of this crate. Here we list how to access nested plumbing crates which are otherwise harder to discover:

git_repository::

§libgit2 API to gix

This doc-aliases are used to help finding methods under a possibly changed name. Just search in the docs. Entering git2 into the search field will also surface all methods with such annotations.

What follows is a list of methods you might be missing, along with workarounds if available.

§Integrity checks

git2 by default performs integrity checks via strict_hash_verification() and strict_object_creation which gitoxide currently does not have.

§Feature Flags

There are various categories of features which help to optimize performance and build times. gix comes with ‘batteries included’ and everything is enabled as long as it doesn’t sacrifice compatibility. Most users will be fine with that but will pay with higher compile times than necessary as they probably don’t use all of these features.

Thus it’s recommended to take a moment and optimize build times by choosing only those ‘Components’ that you require. ‘Performance’ relevant features should be chosen next to maximize efficiency.

§Application Developers

These are considered the end-users, all they need to tune is Performance features to optimize the efficiency of their app, assuming they don’t use gix directly. Otherwise, see the Library Developers paragraph.

In order to configure a crate that isn’t a direct dependency, one has to make it a direct dependency. We recommend gix-for-configuration = { package = "gix", version = "X.Y.Z", features = […] } to make clear this dependency isn’t used in code.

§Library Developers

As a developer of a library, you should start out with gix = { version = "X.Y.Z", default-features = false } and add components as you see fit. For best compatibility, do not activate max-performance-safe or any other performance options.

§Bundles

A bundle is a set of related feature toggles which can be activated with a single name that acts as a group. Bundles are for convenience only and bear no further meaning beyond the cargo manifest file.

  • basic (enabled by default) — More fundamental components that most will be able to make good use of.
  • extras (enabled by default) — Various additional features and capabilities that are not necessarily part of what most users would need.
  • comfort (enabled by default) — Various progress-related features that improve the look of progress message units.
§Components

A component is a distinct feature which may be comprised of one or more methods around a particular topic. Providers of libraries should only activate the components they need.

  • command — Provide a top-level command module that helps with spawning commands similarly to git.

  • status — Obtain information similar to git status.

  • interrupt — Utilities for interrupting computations and cleaning up tempfiles.

  • index — Access to .git/index files.

  • dirwalk — Support directory walks with Git-style annoations.

  • credentials — Access to credential helpers, which provide credentials for URLs.

  • worktree-mutation — Various ways to alter the worktree makeup by checkout and reset.

  • excludes — Retrieve a worktree stack for querying exclude information

  • attributes — Query attributes and excludes. Enables access to pathspecs, worktree checkouts, filter-pipelines and submodules.

  • mailmap — Add support for mailmaps, as way of determining the final name of commmiters and authors.

  • revision — Make revspec parsing possible, as well describing revision.

  • revparse-regex — If enabled, revspecs now support the regex syntax like @^{/^.*x}. Otherwise, only substring search is supported. This feature does increase compile time for niche-benefit, but is required for fully git-compatible revspec parsing.

  • blob-diff — Make it possible to diff blobs line by line. Note that this feature is integral for implementing tree-diffs as well due to the handling of rename-tracking, which relies on line-by-line diffs in some cases.

  • worktree-stream — Make it possible to turn a tree into a stream of bytes, which can be decoded to entries and turned into various other formats.

  • worktree-archive — Create archives from a tree in the repository, similar to what git archive does.

    Note that we disable all default features which strips it off all container support, like tar and zip. Your application should add it as dependency and re-activate the desired features.

§Mutually Exclusive Network Client

Either async-* or blocking-* versions of these toggles may be enabled at a time. For this reason, these must be chosen by the user of the library and can’t be pre-selected. Making a choice here also affects which crypto-library ends up being used.

  • async-network-client — Make gix-protocol available along with an async client.
  • async-network-client-async-std — Use this if your crate uses async-std as runtime, and enable basic runtime integration when connecting to remote servers via the git:// protocol.
  • blocking-network-client — Make gix-protocol available along with a blocking client, providing access to the file://, git:// and ssh:// transports.
  • blocking-http-transport-curl — Stacks with blocking-network-client to provide support for HTTP/S using curl, and implies blocking networking as a whole, making the https:// transport available.
  • blocking-http-transport-curl-rustls — Stacks with blocking-http-transport-curl and also enables the rustls backend to avoid openssl.
  • blocking-http-transport-reqwest — Stacks with blocking-network-client to provide support for HTTP/S using reqwest, and implies blocking networking as a whole, making the https:// transport available.
  • blocking-http-transport-reqwest-rust-tls — Stacks with blocking-http-transport-reqwest and enables https:// via the rustls crate.
  • blocking-http-transport-reqwest-rust-tls-trust-dns — Stacks with blocking-http-transport-reqwest and enables https:// via the rustls crate. This also makes use of trust-dns to avoid getaddrinfo, but note it comes with its own problems.
  • blocking-http-transport-reqwest-native-tls — Stacks with blocking-http-transport-reqwest and enables https:// via the native-tls crate.
§Performance

The reason these features exist is to allow optimization for compile time and optimize for compatibility by default. This means that some performance options around SHA1 and ZIP might not compile on all platforms, so it depends on the end-user who compiles the application to chose these based on their needs.

  • max-control — Activate features that maximize performance, like using threads, but leave everything else that might affect compatibility out to allow users more fine-grained control over performance features like which zlib* implementation to use. No C toolchain is involved.

  • max-performance-safe (enabled by default) — Activate features that maximize performance, like usage of threads, `and access to caching in object databases, skipping the ones known to cause compile failures on some platforms. Note that this configuration still uses a pure Rust zlib implementation which isn’t the fastest compared to its C-alternatives. No C toolchain is involved.

  • parallel-walkdir — If set, walkdir iterators will be multi-threaded which affects the listing of loose objects and references. Note, however, that this will use rayon under the hood and spawn threads for each traversal to avoid a global rayon thread pool. Thus this option is more interesting to one-off client applications, rather than the server.

  • hp-tempfile-registry — The tempfile registry uses a better implementation of a thread-safe hashmap, relying on an external crate. This may be useful when tempfiles are created and accessed in a massively parallel fashion and you know that this is indeed faster than the simpler implementation that is the default.

  • parallel — Make certain data structure threadsafe (or Sync) to facilitate multithreading. Further, many algorithms will now use multiple threads by default.

    If unset, most of gix can only be used in a single thread as data structures won’t be Send anymore.

  • pack-cache-lru-static — Provide a fixed-size allocation-free LRU cache for packs. It’s useful if caching is desired while keeping the memory footprint for the LRU-cache itself low.

  • pack-cache-lru-dynamic — Provide a hash-map based LRU cache whose eviction is based a memory cap calculated from object data.

  • max-performance — Activate other features that maximize performance, like usage of threads, zlib-ng and access to caching in object databases. Note that some platforms might suffer from compile failures, which is when max-performance-safe should be used.

  • fast-sha1 — If enabled, use assembly versions of sha1 on supported platforms. This might cause compile failures as well which is why it can be turned off separately.

  • zlib-ng — Use the C-based zlib-ng backend, which can compress and decompress significantly faster. Note that this will cause duplicate symbol errors if the application also depends on zlib - use zlib-ng-compat in that case.

  • zlib-ng-compat — Use zlib-ng via its zlib-compat API. Useful if you already need zlib for C code elsewhere in your dependencies. Otherwise, use zlib-ng.

  • zlib-stock — Use a slower C-based backend which can compress and decompress significantly faster than the rust version. Unlike zlib-ng-compat, this allows using dynamic linking with system zlib libraries and doesn’t require cmake.

§Other

The catch-all of feature toggles.

  • verbose-object-parsing-errors — When parsing objects by default errors will only be available on the granularity of success or failure, and with the above flag enabled details information about the error location will be collected. Use it in applications which expect broken or invalid objects or for debugging purposes. Incorrectly formatted objects aren’t very common otherwise.

  • serde — Data structures implement serde::Serialize and serde::Deserialize.

  • progress-tree — Re-export the progress tree root which allows to obtain progress from various functions which take impl gix::Progress. Applications which want to display progress will probably need this implementation.

  • cache-efficiency-debug — Print debugging information about usage of object database caches, useful for tuning cache sizes.

  • regex — For use in rev-parse, which provides searching commits by running a regex on their message.

    If disabled, the text will be search verbatim in any portion of the commit message, similar to how a simple unanchored regex of only ‘normal’ characters would work.

Re-exports§

Modules§

Structs§

  • AttributeStackexcludes or attributes
    A utility to access .gitattributes and .gitignore information efficiently.
  • Blob
    A blob along with access to its owning repository.
  • Commit
    A decoded commit object with access to its owning repository.
  • Head
    The head reference, as created from looking at .git/HEAD, able to represent all of its possible states.
  • Id
    An ObjectId with access to a repository.
  • Object
    A decoded object with a reference to its owning repository.
  • ObjectDetached
    A detached, self-contained object, without access to its source repository.
  • Pathspecattributes
    A utility to make matching against pathspecs simple.
  • PathspecDetachedattributes
    Like Pathspec, but without a Repository reference and with minimal API.
  • Reference
    A reference that points to an object or reference, with access to its source repository.
  • Remote
    A remote which represents a way to interact with hosts for remote clones of the parent repository.
  • Repository
    A thread-local handle to interact with a repository from a single thread.
  • Submoduleattributes
    A stand-in for the submodule of a particular name.
  • Tag
    A decoded tag object with access to its owning repository.
  • ThreadSafeRepository
    An instance with access to everything a git repository entails, best imagined as container implementing Sync + Send for most for system resources required to interact with a git repository which are loaded in once the instance is created.
  • Tree
    A decoded tree object with access to its owning repository.
  • Url
    A URL with support for specialized git related capabilities.
  • Worktree
    A worktree checkout containing the files of the repository in consumable form.
  • oid
    A borrowed reference to a hash identifying objects.

Enums§

  • ObjectId
    An owned hash identifying objects, most commonly Sha1

Traits§

  • Count
    A thread-safe read-only counter, with unknown limits.
  • DynNestedProgress
    An object-safe trait for describing hierarchical progress.
  • NestedProgress
    A trait for describing hierarchical progress.
  • Progress
    A trait for describing non-hierarchical progress.

Functions§

Type Aliases§

  • OdbHandle
    A handle for finding objects in an object database, abstracting away caches for thread-local use.
  • RefStore
    The standard type for a store to handle git references.