metadata

Documentation

Overview

Package metadata provides primitives for recording metadata across the query path. Metadata is passed through the query context.

Index

• Variables
• func ExtendHeaders(dst map[string][]string, src []*definitions.PrometheusResponseHeader)
• func JoinHeaders(ctx context.Context, headers []*definitions.PrometheusResponseHeader) error
• type Context
  • func FromContext(ctx context.Context) *Context
  • func NewContext(ctx context.Context) (*Context, context.Context)
  • func (c *Context) Headers() []*definitions.PrometheusResponseHeader

Variables

var (
	ErrNoCtxData = errors.New("unable to add headers to context: no existing context data")
)

Functions

func ExtendHeaders

func ExtendHeaders(dst map[string][]string, src []*definitions.PrometheusResponseHeader)

func JoinHeaders

func JoinHeaders(ctx context.Context, headers []*definitions.PrometheusResponseHeader) error

JoinHeaders merges a Headers with the embedded Headers in a context in a concurrency-safe manner. JoinHeaders will consolidate all distinct headers but will override same-named headers in an undefined way

Types

type Context

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

Context is the metadata context. It is passed through the query path and accumulates metadata.

func FromContext

func FromContext(ctx context.Context) *Context

FromContext returns the metadata context.

func NewContext

func NewContext(ctx context.Context) (*Context, context.Context)

NewContext creates a new metadata context

func (*Context) Headers

func (c *Context) Headers() []*definitions.PrometheusResponseHeader

Headers returns the cache headers accumulated in the context so far.