Struct Generation 

pub struct Generation(/* private fields */);

Generation numbers stored in the database, used for optimistic concurrency control

Generation numbers are monotonic counters: each successive version of a resource is assigned a generation number greater than the one before it.

Implementations

impl Generation

pub const ZERO: Generation

The generation number before any change has been applied, 0.

Generation numbers conventionally start at 1 (see Self::new). Zero is reserved to represent an initial or empty state that precedes the first generation.

pub const MAX: Generation

The largest possible generation number, 2**63 - 1.

pub const fn new() -> Generation

Creates the first generation number, which is 1.

There is deliberately no Default impl: whether a value should start at Self::ZERO or at the first generation is a choice callers must make explicitly.

pub const fn from_u32(value: u32) -> Generation

Creates a generation number from a u32.

Every u32 is a valid generation number, so this conversion is infallible.

pub const fn next(&self) -> Generation

Returns the next generation number.

Panics

Panics if the next generation number would exceed Generation::MAX. Use Self::checked_next to handle overflow instead.

pub const fn checked_next(&self) -> Option<Generation>

Returns the next generation number, or None if it would exceed Generation::MAX.

pub const fn prev(&self) -> Option<Generation>

Returns the previous generation number, or None if this is the first generation.

Both 1 and Self::ZERO are treated as having no predecessor: prev never returns Self::ZERO.

pub const fn as_u64(self) -> u64

Returns the generation number as a u64.

pub const fn as_i64(self) -> i64

Returns the generation number as an i64.

This conversion is infallible because generation numbers are restricted to 2**63 - 1.

Trait Implementations

impl Arbitrary for Generation

Available on crate feature proptest1 only.

Generates random Generation instances.

Values are drawn uniformly from the range 0..=Generation::MAX.

type Parameters = GenerationParams

The type of parameters that arbitrary_with accepts for configuration of the generated Strategy. Parameters must implement Default.

type Strategy = BoxedStrategy<Generation>

The type of Strategy used to generate values of type Self.

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self). The strategy is passed the arguments given in args.

fn arbitrary() -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self).

impl Clone for Generation

fn clone(&self) -> Generation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Generation

impl Debug for Generation

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Generation

Available on crate feature serde only.

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Diffable for Generation

Available on crate feature daft01 only.

Diffs a Generation as a leaf value.

Generation numbers are scalars, so diffing stops at them.

type Diff<'daft> = Leaf<&'daft Generation>

The type of the diff.

fn diff<'daft>(&'daft self, other: &'daft Self) -> Self::Diff<'daft>

Compute the diff between two values.

impl Display for Generation

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

Formats the value using the given formatter.

impl Eq for Generation

impl From<&Generation> for i64

fn from(g: &Generation) -> Self

Converts to this type from the input type.

impl From<Generation> for u64

fn from(g: Generation) -> Self

Converts to this type from the input type.

impl From<Generation> for i64

fn from(g: Generation) -> Self

Converts to this type from the input type.

impl From<u32> for Generation

fn from(value: u32) -> Self

Converts to this type from the input type.

impl FromStr for Generation

type Err = ParseIntError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl GenericGeneration for Generation

fn from_untyped_generation(generation: Generation) -> Self

Creates a new instance of Self from an untyped Generation.

fn into_untyped_generation(self) -> Generation

Converts self into an untyped Generation.

fn as_untyped_generation(&self) -> &Generation

Returns the inner Generation.

impl Hash for Generation

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 JsonSchema for Generation

Available on crate feature schemars08 only.

Implements JsonSchema for Generation.

The schema is that of a u64 with a minimum of 0; the upper bound is not expressed in the schema. The description matches the first line of the doc comment on Generation.

fn schema_name() -> String

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(_: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn is_referenceable() -> bool

Whether JSON Schemas generated for this type should be re-used where possible using the $ref keyword.

impl Ord for Generation

fn cmp(&self, other: &Generation) -> 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 PartialEq for Generation

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for Generation

fn partial_cmp(&self, other: &Generation) -> 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 Generation

Available on crate feature serde only.

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Generation

impl TryFrom<i64> for Generation

type Error = GenerationNegativeError

The type returned in the event of a conversion error.

fn try_from(value: i64) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<u64> for Generation

type Error = GenerationOverflowError

The type returned in the event of a conversion error.

fn try_from(value: u64) -> Result<Self, Self::Error>

Performs the conversion.

impl Value for Generation

Available on crate feature slog2 only.

Logs a Generation as an integer.

fn serialize( &self, _rec: &Record<'_>, key: Key, serializer: &mut dyn Serializer, ) -> Result

Serialize self into Serializer