correlation

package
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Published: Sep 2, 2021 License: Apache-2.0 Imports: 6 Imported by: 0

Documentation

Overview

This package implements the correlation functionality as specified in the OpenTelemetry specification. Currently it provides a data structure for storing correlations (Map) and a way of putting Map object into the context and retrieving it from context.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func ContextWithGetHook

func ContextWithGetHook(ctx context.Context, hook GetHookFunc) context.Context

ContextWithGetHook installs a hook function that will be invoked every time MapFromContext is called. To avoid unnecessary callback invocations (recursive or not), the callback can temporarily clear the hooks from the context with the ContextWithNoHooks function.

Note that NewContext also calls MapFromContext, so the hook will be invoked.

Passing nil GetHookFunc creates a context with no get hook to call.

This function should not be used by applications or libraries. It is mostly for interoperation with other observability APIs.

func ContextWithMap

func ContextWithMap(ctx context.Context, m Map) context.Context

ContextWithMap returns a context with the Map entered into it.

func ContextWithNoHooks

func ContextWithNoHooks(ctx context.Context) (context.Context, SetHookFunc, GetHookFunc)

ContextWithNoHooks creates a context with all the hooks disabled. Also returns old set and get hooks. This function can be used to temporarily clear the context from hooks and then reinstate them by calling ContextWithSetHook and ContextWithGetHook functions passing the hooks returned by this function.

This function should not be used by applications or libraries. It is mostly for interoperation with other observability APIs.

func ContextWithSetHook

func ContextWithSetHook(ctx context.Context, hook SetHookFunc) context.Context

ContextWithSetHook installs a hook function that will be invoked every time ContextWithMap is called. To avoid unnecessary callback invocations (recursive or not), the callback can temporarily clear the hooks from the context with the ContextWithNoHooks function.

Note that NewContext also calls ContextWithMap, so the hook will be invoked.

Passing nil SetHookFunc creates a context with no set hook to call.

This function should not be used by applications or libraries. It is mostly for interoperation with other observability APIs.

func DefaultHTTPPropagator

func DefaultHTTPPropagator() propagation.HTTPPropagator

DefaultHTTPPropagator returns the default context correlation HTTP propagator.

func NewContext

func NewContext(ctx context.Context, keyvalues ...core.KeyValue) context.Context

NewContext returns a context with the map from passed context updated with the passed key-value pairs.

Types

type CorrelationContext

type CorrelationContext struct{}

CorrelationContext propagates Key:Values in W3C CorrelationContext format. nolint:golint

func (CorrelationContext) Extract

Extract implements HTTPExtractor.

func (CorrelationContext) GetAllKeys

func (CorrelationContext) GetAllKeys() []string

GetAllKeys implements HTTPPropagator.

func (CorrelationContext) Inject

Inject implements HTTPInjector.

type GetHookFunc

type GetHookFunc func(context.Context, Map) Map

GetHookFunc describes a type of a callback that is called when getting baggage from the context.

type Map

type Map struct {
	// contains filtered or unexported fields
}

Map is an immutable storage for correlations.

func MapFromContext

func MapFromContext(ctx context.Context) Map

MapFromContext gets the current Map from a Context.

func NewEmptyMap

func NewEmptyMap() Map

NewEmptyMap creates an empty correlations map.

func NewMap

func NewMap(update MapUpdate) Map

NewMap creates a map with the contents of the update applied. In this function, having an update with DropSingleK or DropMultiK makes no sense - those fields are effectively ignored.

func (Map) Apply

func (m Map) Apply(update MapUpdate) Map

Apply creates a copy of the map with the contents of the update applied. Apply will first drop the keys from DropSingleK and DropMultiK, then add key-value pairs from SingleKV and MultiKV.

func (Map) Foreach

func (m Map) Foreach(f func(kv core.KeyValue) bool)

Foreach calls a passed callback once on each key-value pair until all the key-value pairs of the map were iterated or the callback returns false, whichever happens first.

func (Map) HasValue

func (m Map) HasValue(k core.Key) bool

HasValue returns a boolean value indicating whether the key exist in the map.

func (Map) Len

func (m Map) Len() int

Len returns a length of the map.

func (Map) Value

func (m Map) Value(k core.Key) (core.Value, bool)

Value gets a value from correlations map and returns a boolean value indicating whether the key exist in the map.

type MapUpdate

type MapUpdate struct {
	// DropSingleK contains a single key to be dropped from
	// correlations. Use this to avoid an overhead of a slice
	// allocation if there is only one key to drop.
	DropSingleK core.Key
	// DropMultiK contains all the keys to be dropped from
	// correlations.
	DropMultiK []core.Key

	// SingleKV contains a single key-value pair to be added to
	// correlations. Use this to avoid an overhead of a slice
	// allocation if there is only one key-value pair to add.
	SingleKV core.KeyValue
	// MultiKV contains all the key-value pairs to be added to
	// correlations.
	MultiKV []core.KeyValue
}

MapUpdate contains information about correlation changes to be made.

type SetHookFunc

type SetHookFunc func(context.Context) context.Context

SetHookFunc describes a type of a callback that is called when storing baggage in the context.

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