Class: Priority
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:
- First, consider "priority": higher priority (lower number) goes first.
- 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.)
Implements
Constructors
constructor
• new Priority(properties?): Priority
Constructs a new Priority.
Parameters
| Name | Type | Description |
|---|---|---|
properties? | IPriority | Properties to set |
Returns
Properties
fairnessKey
• fairnessKey: 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.
Implementation of
fairnessWeight
• fairnessWeight: number
Fairness weight for a task can come from multiple sources for flexibility. From highest to lowest precedence:
- Weights for a small set of keys can be overridden in task queue configuration with an API.
- It can be attached to the workflow/activity in this field.
- The default weight of 1.0 will be used.
Weight values are clamped to the range [0.001, 1000].
Implementation of
priorityKey
• priorityKey: number
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 is calculated by (min+max)/2. With the default max of 5, and min of 1, that comes out to 3.
Implementation of
Methods
toJSON
▸ toJSON(): Object
Converts this Priority to JSON.
Returns
Object
JSON object
create
▸ create(properties?): Priority
Creates a new Priority instance using the specified properties.
Parameters
| Name | Type | Description |
|---|---|---|
properties? | IPriority | Properties to set |
Returns
Priority instance
decode
▸ decode(reader, length?): Priority
Decodes a Priority message from the specified reader or buffer.
Parameters
| Name | Type | Description |
|---|---|---|
reader | Uint8Array | Reader | Reader or buffer to decode from |
length? | number | Message length if known beforehand |
Returns
Priority
Throws
If the payload is not a reader or valid buffer
Throws
If required fields are missing
decodeDelimited
▸ decodeDelimited(reader): Priority
Decodes a Priority message from the specified reader or buffer, length delimited.
Parameters
| Name | Type | Description |
|---|---|---|
reader | Uint8Array | Reader | Reader or buffer to decode from |
Returns
Priority
Throws
If the payload is not a reader or valid buffer
Throws
If required fields are missing
encode
▸ encode(message, writer?): Writer
Encodes the specified Priority message. Does not implicitly temporal.api.common.v1.Priority.verify|verify messages.
Parameters
| Name | Type | Description |
|---|---|---|
message | IPriority | Priority message or plain object to encode |
writer? | Writer | Writer to encode to |
Returns
Writer
Writer
encodeDelimited
▸ encodeDelimited(message, writer?): Writer
Encodes the specified Priority message, length delimited. Does not implicitly temporal.api.common.v1.Priority.verify|verify messages.
Parameters
| Name | Type | Description |
|---|---|---|
message | IPriority | Priority message or plain object to encode |
writer? | Writer | Writer to encode to |
Returns
Writer
Writer
fromObject
▸ fromObject(object): Priority
Creates a Priority message from a plain object. Also converts values to their respective internal types.
Parameters
| Name | Type | Description |
|---|---|---|
object | Object | Plain object |
Returns
Priority
getTypeUrl
▸ getTypeUrl(typeUrlPrefix?): string
Gets the default type url for Priority
Parameters
| Name | Type | Description |
|---|---|---|
typeUrlPrefix? | string | your custom typeUrlPrefix(default "type.googleapis.com") |
Returns
string
The default type url
toObject
▸ toObject(message, options?): Object
Creates a plain object from a Priority message. Also converts values to other types if specified.
Parameters
| Name | Type | Description |
|---|---|---|
message | Priority | Priority |
options? | IConversionOptions | Conversion options |
Returns
Object
Plain object