101 lines
2.5 KiB
Go
101 lines
2.5 KiB
Go
// Package metadata is a way of defining message headers
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package metadata
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import (
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"context"
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)
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type (
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mdIncomingKey struct{}
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mdOutgoingKey struct{}
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mdKey struct{}
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)
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// FromIncomingContext returns metadata from incoming ctx
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// returned metadata shoud not be modified or race condition happens
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func FromIncomingContext(ctx context.Context) (Metadata, bool) {
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if ctx == nil {
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return nil, false
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}
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md, ok := ctx.Value(mdIncomingKey{}).(Metadata)
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if !ok || md == nil {
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return nil, false
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}
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return md, ok
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}
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// FromOutgoingContext returns metadata from outgoing ctx
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// returned metadata shoud not be modified or race condition happens
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func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
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if ctx == nil {
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return nil, false
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}
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md, ok := ctx.Value(mdOutgoingKey{}).(Metadata)
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if !ok || md == nil {
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return nil, false
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}
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return md, ok
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}
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// FromContext returns metadata from the given context
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// returned metadata shoud not be modified or race condition happens
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func FromContext(ctx context.Context) (Metadata, bool) {
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if ctx == nil {
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return nil, false
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}
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md, ok := ctx.Value(mdKey{}).(Metadata)
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if !ok || md == nil {
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return nil, false
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}
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return md, ok
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}
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// NewContext creates a new context with the given metadata
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func NewContext(ctx context.Context, md Metadata) context.Context {
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if ctx == nil {
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ctx = context.Background()
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}
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ctx = context.WithValue(ctx, mdKey{}, md)
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return ctx
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}
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// NewIncomingContext creates a new context with incoming metadata attached
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func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
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if ctx == nil {
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ctx = context.Background()
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}
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ctx = context.WithValue(ctx, mdIncomingKey{}, md)
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return ctx
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}
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// NewOutgoingContext creates a new context with outcoming metadata attached
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func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
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if ctx == nil {
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ctx = context.Background()
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}
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ctx = context.WithValue(ctx, mdOutgoingKey{}, md)
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return ctx
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}
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// AppendOutgoingContext apends new md to context
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func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
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md := Pairs(kv...)
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omd, ok := FromOutgoingContext(ctx)
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if !ok {
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return NewOutgoingContext(ctx, md)
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}
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nmd := Merge(omd, md, true)
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return NewOutgoingContext(ctx, nmd)
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}
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// AppendIncomingContext apends new md to context
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func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
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md := Pairs(kv...)
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omd, ok := FromIncomingContext(ctx)
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if !ok {
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return NewIncomingContext(ctx, md)
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}
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nmd := Merge(omd, md, true)
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return NewIncomingContext(ctx, nmd)
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}
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