Struct LazyProto

pub struct LazyProto<T> {
    buf: Bytes,
    _phantom: PhantomData<fn() -> T>,
}

A proto that is decoded on use.

Because of the way prost works, decoding a large protobuf may result in a number of very short lived allocations in our RustType/ProtoType decode path (e.g. this happens for a repeated embedded message). Not every use of persist State needs every transitive bit of it to be decoded, so we opt certain parts of it (initially stats) to be decoded on use.

This has the dual benefit of only paying for the short-lived allocs when necessary and also allowing decoding to be gated by a feature flag. The tradeoffs are that we might decode more than once and that we have to handle invalid proto errors in more places.

Mechanically, this is accomplished by making the field a proto bytes types instead of ProtoFoo. These bytes then contain the serialization of ProtoFoo. NB: Swapping between the two is actually a forward and backward compatible change.

Embedded messages are compatible with bytes if the bytes contain an encoded version of the message.

(See https://protobuf.dev/programming-guides/proto3/#updating)

Fields

buf: Bytes

_phantom: PhantomData<fn() -> T>

Implementations

impl<T: Message + Default> LazyProto<T>

pub fn decode(&self) -> Result<T, DecodeError>

pub fn decode_to<R: RustType<T>>(&self) -> Result<R>

Trait Implementations

impl<T: Clone> Clone for LazyProto<T>

fn clone(&self) -> LazyProto<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Message + Default> Debug for LazyProto<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for LazyProto<T>

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T: Message + Default> From<&T> for LazyProto<T>

fn from(value: &T) -> Self

Converts to this type from the input type.

impl<T> Hash for LazyProto<T>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T> Ord for LazyProto<T>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T> PartialEq for LazyProto<T>

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialOrd for LazyProto<T>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Message + Default> RustType<Bytes> for LazyProto<T>

fn into_proto(&self) -> Bytes

Convert a Self into a Proto value.

fn from_proto(buf: Bytes) -> Result<Self, TryFromProtoError>

Consume and convert a Proto back into a Self value.

fn into_proto_owned(self) -> Proto

A zero clone version of Self::into_proto that types can optionally implement, otherwise, the default implementation delegates to Self::into_proto.

impl<T> Serialize for LazyProto<T>

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T> Eq for LazyProto<T>