Struct Priority 

pub struct Priority {
    pub priority_key: i32,
    pub fairness_key: String,
    pub fairness_weight: f32,
}

Priority contains metadata that controls relative ordering of task processing when tasks are backed up in a queue. Initially, Priority will be used in matching (workflow and activity) task queues. Later it may be used in history task queues and in rate limiting decisions.

Priority is attached to workflows and activities. By default, activities inherit Priority from the workflow that created them, but may override fields when an activity is started or modified.

Despite being named “Priority”, this message also contains fields that control “fairness” mechanisms.

For all fields, the field not present or equal to zero/empty string means to inherit the value from the calling workflow, or if there is no calling workflow, then use the default value.

For all fields other than fairness_key, the zero value isn’t meaningful so there’s no confusion between inherit/default and a meaningful value. For fairness_key, the empty string will be interpreted as “inherit”. This means that if a workflow has a non-empty fairness key, you can’t override the fairness key of its activity to the empty string.

The overall semantics of Priority are:

1. First, consider “priority”: higher priority (lower number) goes first.
2. Then, consider fairness: try to dispatch tasks for different fairness keys in proportion to their weight.

Applications may use any subset of mechanisms that are useful to them and leave the other fields to use default values.

Not all queues in the system may support the “full” semantics of all priority fields. (Currently only support in matching task queues is planned.)

Fields

priority_key: i32

Priority key is a positive integer from 1 to n, where smaller integers correspond to higher priorities (tasks run sooner). In general, tasks in a queue should be processed in close to priority order, although small deviations are possible.

The maximum priority value (minimum priority) is determined by server configuration, and defaults to 5.

If priority is not present (or zero), then the effective priority will be the default priority, which is calculated by (min+max)/2. With the default max of 5, and min of 1, that comes out to 3.

fairness_key: String

Fairness key is a short string that’s used as a key for a fairness balancing mechanism. It may correspond to a tenant id, or to a fixed string like “high” or “low”. The default is the empty string.

The fairness mechanism attempts to dispatch tasks for a given key in proportion to its weight. For example, using a thousand distinct tenant ids, each with a weight of 1.0 (the default) will result in each tenant getting a roughly equal share of task dispatch throughput.

(Note: this does not imply equal share of worker capacity! Fairness decisions are made based on queue statistics, not current worker load.)

As another example, using keys “high” and “low” with weight 9.0 and 1.0 respectively will prefer dispatching “high” tasks over “low” tasks at a 9:1 ratio, while allowing either key to use all worker capacity if the other is not present.

All fairness mechanisms, including rate limits, are best-effort and probabilistic. The results may not match what a “perfect” algorithm with infinite resources would produce. The more unique keys are used, the less accurate the results will be.

Fairness keys are limited to 64 bytes.

fairness_weight: f32

Fairness weight for a task can come from multiple sources for flexibility. From highest to lowest precedence:

1. Weights for a small set of keys can be overridden in task queue configuration with an API.
2. It can be attached to the workflow/activity in this field.
3. The default weight of 1.0 will be used.

Weight values are clamped to the range [0.001, 1000].

Trait Implementations

impl Clone for Priority

fn clone(&self) -> Priority

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Priority

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

Formats the value using the given formatter.

impl Default for Priority

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Priority

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

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<Priority> for Priority

fn from(priority: Priority) -> Self

Converts to this type from the input type.

impl From<Priority> for Priority

fn from(priority: Priority) -> Self

Converts to this type from the input type.

impl Message for Priority

fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

impl Name for Priority

const NAME: &'static str = "Priority"

Simple name for this Message. This name is the same as it appears in the source .proto file, e.g. FooBar.

const PACKAGE: &'static str = "temporal.api.common.v1"

Package name this message type is contained in. They are domain-like and delimited by ., e.g. google.protobuf.

fn full_name() -> String

Fully-qualified unique name for this Message. It’s prefixed with the package name and names of any parent messages, e.g. google.rpc.BadRequest.FieldViolation. By default, this is the package name followed by the message name. Fully-qualified names must be unique within a domain of Type URLs.

fn type_url() -> String

Type URL for this Message, which by default is the full name with a leading slash, but may also include a leading domain name, e.g. type.googleapis.com/google.profile.Person. This can be used when serializing into the google.protobuf.Any type.

impl PartialEq for Priority

fn eq(&self, other: &Priority) -> 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 Serialize for Priority

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 Priority