# Struct cargo::sources::registry::index::Summaries

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    struct Summaries {
        raw_data: Vec<u8>,
        versions: HashMap<Version, MaybeIndexSummary>,
    }

Expand description

An internal cache of summaries for a particular package.

A list of summaries are loaded from disk via one of two methods:

1. From raw registry index — Primarily Cargo will parse the corresponding file for a crate in the upstream crates.io registry. That’s just a JSON blob per line which we can parse, extract the version, and then store here. See `IndexPackage` and `IndexSummary::parse`.

2. From on-disk index cache — If Cargo has previously run, we’ll have a cached index of dependencies for the upstream index. This is a file that Cargo maintains lazily on the local filesystem and is much faster to parse since it doesn’t involve parsing all of the JSON. See `SummariesCache`.

The outward-facing interface of this doesn’t matter too much where it’s loaded from, but it’s important when reading the implementation to note that we try to parse as little as possible!

## Fields§

§`raw_data: Vec<u8>`

A raw vector of uninterpreted bytes. This is what `Unparsed` start/end fields are indexes into. If a `Summaries` is loaded from the crates.io index then this field will be empty since nothing is `Unparsed`.

§`versions: HashMap<Version, MaybeIndexSummary>`

All known versions of a crate, keyed from their `Version` to the possibly parsed or unparsed version of the full summary.

## Implementations§

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### impl Summaries

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#### pub fn parse( root: &Path, cache_root: &Path, relative: &Path, source_id: SourceId, load: &mut dyn RegistryData, config: &Config ) -> Poll<CargoResult<Option<Summaries>>>

Parse out a `Summaries` instances from on-disk state.

This will do the followings in order:

1. Attempt to prefer parsing a previous index cache file that already exists from a previous invocation of Cargo (aka you’re typing `cargo build` again after typing it previously).
2. If parsing fails, or the cache isn’t found or is invalid, we then take a slower path which loads the full descriptor for `relative` from the underlying index (aka libgit2 with crates.io, or from a remote HTTP index) and then parse everything in there.

- `root` — this is the root argument passed to `load`
- `cache_root` — this is the root on the filesystem itself of where to store cache files.
- `relative` — this is the file we’re loading from cache or the index data
- `source_id` — the registry’s SourceId used when parsing JSON blobs to create summaries.
- `load` — the actual index implementation which may be very slow to call. We avoid this if we can.

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#### pub fn parse_cache( contents: Vec<u8> ) -> CargoResult<(Summaries, InternedString)>

Parses the contents of an on-disk cache, aka `SummariesCache`, which represents information previously cached by Cargo.

## Trait Implementations§

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### impl Default for Summaries

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#### fn default() -> Summaries

Returns the “default value” for a type. Read more

## Auto Trait Implementations§

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### impl RefUnwindSafe for Summaries

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### impl !Send for Summaries

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### impl !Sync for Summaries

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### impl Unpin for Summaries

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### impl UnwindSafe for Summaries

## Blanket Implementations§

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### impl<T> Any for Twhere T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for Twhere T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [`Span`], returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for Twhere U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 72 bytes