Interface IW3cTraceState

Represents a mutable W3C trace state list, this is a list of key/value pairs that are used to pass trace state information between different tracing systems. The list is ordered and the order is important as it determines the processing order.

Importantly instances of this type are mutable, change made to an instance via IW3cTraceState.set or IW3cTraceState.del will be reflected on the instance and any child instances that use it as a parent. However, any parent instance associated with an instance will not be modified by operations on that particular instance.

Since

3.4.0

interface IW3cTraceState {
    child(): IW3cTraceState;
    del(key: string): void;
    get(key: string): string;
    hdrs(maxHeaders?: number, maxKeys?: number, maxLen?: number): string[];
    isEmpty: boolean;
    keys: string[];
    set(key: string, value: string): number;
}

Properties

isEmpty keys

Methods

child del get hdrs set

Properties

ReadonlyisEmpty

isEmpty: boolean

Check if the trace state list is empty, meaning it has no keys or values. This exists to allow for quick checks without needing to create a new array of keys.

Since

3.4.0

Returns

true if the trace state list is empty, false otherwise

Readonlykeys

keys: string[]

Returns a readonly array of the current keys associated with the trace state, keys are returned in the required processing order and if this instance has a parent the keys from the parent will be included unless they have been removed (deleted) from the child instance. Once created any modifications to the parent will also be reflected in the child, this is different from the OpenTelemetry implementation which creates a new instance for each call.

Returns

A readonly array of the current keys associated with the trace state

Methods

child

  • child(): IW3cTraceState

  • Create a new instance of IW3cTraceState which is a child of this instance, meaning it will inherit the keys and values from this instance but any changes made to the child will not affect this instance.

    Returns IW3cTraceState

    A new instance of IW3cTraceState which is a child of this instance

del

  • del(key): void

  • Delete the specified key from this instance, if the key was in the parent it will be removed (hidden) from this instance but will still be available directly from the parent.

    Parameters

    • key: string

      The key to delete

    Returns void

get

  • get(key): string

  • Get the value for the specified key that is associated with this instance, either directly or from the parent.

    Parameters

    • key: string

      The key to lookup

    Returns string

    The value for the key, or undefined if not found

hdrs

  • hdrs(maxHeaders?, maxKeys?, maxLen?): string[]

  • Format the trace state list into a strings where each string can be used as a header value. This will return an empty array if the trace state list is empty.

    Parameters

    • OptionalmaxHeaders: number

      The maximum number of entries to include in the output, once the limit is reached no more entries will be included

    • OptionalmaxKeys: number

      The maximum number of keys to include in the output, once the limit is reached no more keys will be included

    • OptionalmaxLen: number

      The maximum length of each header value, once the limit is reached a new header value will be created

    Returns string[]

    An array of strings that can be used for the header values, if the trace state list is empty an empty array will be returned

set

  • set(key, value): number

  • Set the value for the specified key for this instance, returning its new location within the list.

    • 0 is the front of the list
    • -1 not set because the key/value pair is invalid If the key already exists it will be removed from its current location and added to the front of the list. And if the key was in the parent this will override the value inherited from the parent, more importantly it will not modify the parent value.

    Parameters

    • key: string

      The key to set

    • value: string

      The value to set

    Returns number

    0 if successful, -1 if not

Settings

Member Visibility

On This Page

Properties
Methods