micro/metadata/context.go
Vasiliy Tolstov 927c7ea3c2 metadata: allow to modify metadata via SetXXX functions
Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>
2021-02-09 12:46:14 +03:00

109 lines
2.8 KiB
Go

// Package metadata is a way of defining message headers
package metadata
import (
"context"
)
type mdIncomingKey struct{}
type mdOutgoingKey struct{}
type mdKey struct{}
// FromIncomingContext returns metadata from incoming ctx
// returned metadata shoud not be modified or race condition happens
func FromIncomingContext(ctx context.Context) (Metadata, bool) {
if ctx == nil {
return nil, false
}
md, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata)
if !ok {
return nil, false
}
return md.md, ok
}
// FromOutgoingContext returns metadata from outgoing ctx
// returned metadata shoud not be modified or race condition happens
func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
if ctx == nil {
return nil, false
}
md, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata)
if !ok {
return nil, false
}
return md.md, ok
}
// FromContext returns metadata from the given context
// returned metadata shoud not be modified or race condition happens
//
// Deprecated: use FromIncomingContext or FromOutgoingContext
func FromContext(ctx context.Context) (Metadata, bool) {
if ctx == nil {
return nil, false
}
md, ok := ctx.Value(mdKey{}).(*rawMetadata)
if !ok {
return nil, false
}
return md.md, ok
}
// NewContext creates a new context with the given metadata
//
// Deprecated: use NewIncomingContext or NewOutgoingContext
func NewContext(ctx context.Context, md Metadata) context.Context {
if ctx == nil {
ctx = context.Background()
}
ctx = context.WithValue(ctx, mdKey{}, &rawMetadata{md})
ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{})
ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{})
return ctx
}
// SetOutgoingContext modify outgoing context with given metadata
func SetOutgoingContext(ctx context.Context, md Metadata) bool {
if ctx == nil {
return false
}
if omd, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata); ok {
omd.md = md
return true
}
return false
}
// SetIncomingContext modify incoming context with given metadata
func SetIncomingContext(ctx context.Context, md Metadata) bool {
if ctx == nil {
return false
}
if omd, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata); ok {
omd.md = md
return true
}
return false
}
// NewIncomingContext creates a new context with incoming metadata attached
func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
if ctx == nil {
ctx = context.Background()
}
ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{md})
ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{})
return ctx
}
// NewOutgoingContext creates a new context with outcoming metadata attached
func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
if ctx == nil {
ctx = context.Background()
}
ctx = context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{md})
ctx = context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{})
return ctx
}