Struct WriteVersion 

pub struct WriteVersion {
    pub epoch: u64,
    pub index: u64,
    pub local: u64,
}

The position of the write that produced a row version, within one vShard.

A write that applies a data-group entry records epoch, the epoch at which its vShard moved to the entry’s group, and index, the entry’s log index. local is 0.

A write that applies no entry records its WAL LSN in local, on top of the latest version its vShard holds on the core. Such a write exists on one node only: a single-node write, or a local-only write on a cluster node. It sorts after every version its vShard already holds and before the next entry the vShard applies.

Versions compare only within one vShard. The writes of one vShard are totally ordered by (epoch, index, local).

Fields

epoch: u64

The epoch at which the vShard moved to the group that applied the write. 0 while the vShard stays in its initial group.

index: u64

The log index of the data-group entry that applied the write.

local: u64

The WAL LSN of a write that applies no entry, 0 otherwise.

Implementations

impl WriteVersion

pub const ZERO: Self

The version below every write.

pub const fn logged(epoch: u64, index: u64) -> Self

The version of a write that applies the entry at index, in epoch.

pub const fn local_after(latest: Self, lsn: u64) -> Self

The version of a write that applies no entry, at WAL LSN lsn, on a vShard whose latest version is latest.

pub fn distance_above(self, older: Self) -> Option<u64>

How far self sits above older in one epoch: the log entries between them, or the WAL LSNs between two writes of one entry position. None across epochs, or when older is not below self.

Trait Implementations

impl Archive for WriteVersion

where u64: Archive,

const COPY_OPTIMIZATION: CopyOptimization<Self>

An optimization flag that allows the bytes of this type to be copied directly to a writer instead of calling serialize.

type Archived = ArchivedWriteVersion

The archived representation of this type.

type Resolver = WriteVersionResolver

The resolver for this type. It must contain all the additional information from serializing needed to make the archived type from the normal type.

fn resolve(&self, resolver: Self::Resolver, out: Place<Self::Archived>)

Creates the archived version of this value at the given position and writes it to the given output.

impl Clone for WriteVersion

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WriteVersion

impl Debug for WriteVersion

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

Formats the value using the given formatter.

impl Default for WriteVersion

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for WriteVersion

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<__D: Fallible + ?Sized> Deserialize<WriteVersion, __D> for Archived<WriteVersion>

where u64: Archive, <u64 as Archive>::Archived: Deserialize<u64, __D>,

fn deserialize( &self, deserializer: &mut __D, ) -> Result<WriteVersion, <__D as Fallible>::Error>

Deserializes using the given deserializer

impl Eq for WriteVersion

impl<'__msgpack_de> FromMessagePack<'__msgpack_de> for WriteVersion

fn read<R: Read<'__msgpack_de>>(reader: &mut R) -> Result<Self, Error>

where Self: Sized,

Reads the MessagePack representation of this value from the provided reader.

impl Hash for WriteVersion

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 Ord for WriteVersion

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.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for WriteVersion

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for WriteVersion

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 Serialize for WriteVersion

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<__S: Fallible + ?Sized> Serialize<__S> for WriteVersion

where u64: Serialize<__S>,

fn serialize( &self, serializer: &mut __S, ) -> Result<<Self as Archive>::Resolver, <__S as Fallible>::Error>

Writes the dependencies for the object and returns a resolver that can create the archived type.

impl StructuralPartialEq for WriteVersion

impl ToMessagePack for WriteVersion

fn write<W: Write>(&self, writer: &mut W) -> Result<(), Error>

Writes the MessagePack representation of this value into the provided writer.

fn size_hint(&self) -> Option<TrustedSizeHint>

Returns a trusted upper bound for the number of bytes written by the next call to Self::write, or None when it cannot be determined cheaply.

fn max_size() -> Option<TrustedSizeHint>

Returns a trusted upper bound valid for every value of this type.

fn write_slice<W>(values: &[Self], writer: &mut W) -> Result<(), Error>

where W: Write, Self: Sized,

Writes the MessagePack representation of a slice of values into the provided writer.