metadata

Documentation

Overview

Package metadata define the structure of the metadata supported by gRPC library. Please refer to https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md for more information about custom-metadata.

Index

• func AppendToOutgoingContext(ctx context.Context, kv ...string) context.Context
• func DecodeKeyValue(k, v string) (string, string, error)
• func NewIncomingContext(ctx context.Context, md MD) context.Context
• func NewOutgoingContext(ctx context.Context, md MD) context.Context
• type MD
  • func FromIncomingContext(ctx context.Context) (md MD, ok bool)
  • func FromOutgoingContext(ctx context.Context) (MD, bool)
  • func FromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool)
  • func Join(mds ...MD) MD
  • func New(m map[string]string) MD
  • func Pairs(kv ...string) MD
  • func (md MD) Append(k string, vals ...string)
  • func (md MD) Copy() MD
  • func (md MD) Get(k string) []string
  • func (md MD) Len() int
  • func (md MD) Set(k string, vals ...string)

Functions

func AppendToOutgoingContext

func AppendToOutgoingContext(ctx context.Context, kv ...string) context.Context

AppendToOutgoingContext returns a new context with the provided kv merged with any existing metadata in the context. Please refer to the documentation of Pairs for a description of kv.

func DecodeKeyValue

func DecodeKeyValue(k, v string) (string, string, error)

DecodeKeyValue returns k, v, nil. It is deprecated and should not be used.

func NewIncomingContext

func NewIncomingContext(ctx context.Context, md MD) context.Context

NewIncomingContext creates a new context with incoming md attached.

func NewOutgoingContext

func NewOutgoingContext(ctx context.Context, md MD) context.Context

NewOutgoingContext creates a new context with outgoing md attached. If used in conjunction with AppendToOutgoingContext, NewOutgoingContext will overwrite any previously-appended metadata.

Types

type MD

type MD map[string][]string

MD is a mapping from metadata keys to values. Users should use the following two convenience functions New and Pairs to generate MD.

func FromIncomingContext

func FromIncomingContext(ctx context.Context) (md MD, ok bool)

FromIncomingContext returns the incoming metadata in ctx if it exists. The returned MD should not be modified. Writing to it may cause races. Modification should be made to copies of the returned MD.

func FromOutgoingContext

func FromOutgoingContext(ctx context.Context) (MD, bool)

FromOutgoingContext returns the outgoing metadata in ctx if it exists. The returned MD should not be modified. Writing to it may cause races. Modification should be made to copies of the returned MD.

func FromOutgoingContextRaw

func FromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool)

FromOutgoingContextRaw returns the un-merged, intermediary contents of rawMD. Remember to perform strings.ToLower on the keys. The returned MD should not be modified. Writing to it may cause races. Modification should be made to copies of the returned MD.

This is intended for gRPC-internal use ONLY.

func Join

func Join(mds ...MD) MD

Join joins any number of mds into a single MD. The order of values for each key is determined by the order in which the mds containing those values are presented to Join.

func New

func New(m map[string]string) MD

New creates an MD from a given key-value map.

Only the following ASCII characters are allowed in keys:

• digits: 0-9
• uppercase letters: A-Z (normalized to lower)
• lowercase letters: a-z
• special characters: -_.

Uppercase letters are automatically converted to lowercase.

Keys beginning with "grpc-" are reserved for grpc-internal use only and may result in errors if set in metadata.

func Pairs

func Pairs(kv ...string) MD

Pairs returns an MD formed by the mapping of key, value ... Pairs panics if len(kv) is odd.

Only the following ASCII characters are allowed in keys:

• digits: 0-9
• uppercase letters: A-Z (normalized to lower)
• lowercase letters: a-z
• special characters: -_.

Uppercase letters are automatically converted to lowercase.

Keys beginning with "grpc-" are reserved for grpc-internal use only and may result in errors if set in metadata.

func (MD) Append

func (md MD) Append(k string, vals ...string)

Append adds the values to key k, not overwriting what was already stored at that key.

func (MD) Copy

func (md MD) Copy() MD

Copy returns a copy of md.

func (MD) Get

func (md MD) Get(k string) []string

Get obtains the values for a given key.

func (MD) Len

func (md MD) Len() int

Len returns the number of items in md.

func (MD) Set

func (md MD) Set(k string, vals ...string)

Set sets the value of a given key with a slice of values.