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package test
import (
"context"
"fmt"
"google.golang.org/grpc/metadata"
)
type metaContext string
const (
correlationID metaContext = "correlation-id"
responseHDR metaContext = "my-response-header"
responseTRLR metaContext = "my-response-trailer"
correlationIDTRLR metaContext = "correlation-id-consumed"
)
/* client before functions */
func injectCorrelationID(ctx context.Context, md *metadata.MD) context.Context {
if hdr, ok := ctx.Value(correlationID).(string); ok {
fmt.Printf("\tClient found correlationID %q in context, set metadata header\n", hdr)
(*md)[string(correlationID)] = append((*md)[string(correlationID)], hdr)
}
return ctx
}
func displayClientRequestHeaders(ctx context.Context, md *metadata.MD) context.Context {
if len(*md) > 0 {
fmt.Println("\tClient >> Request Headers:")
for key, val := range *md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
/* server before functions */
func extractCorrelationID(ctx context.Context, md metadata.MD) context.Context {
if hdr, ok := md[string(correlationID)]; ok {
cID := hdr[len(hdr)-1]
ctx = context.WithValue(ctx, correlationID, cID)
fmt.Printf("\tServer received correlationID %q in metadata header, set context\n", cID)
}
return ctx
}
func displayServerRequestHeaders(ctx context.Context, md metadata.MD) context.Context {
if len(md) > 0 {
fmt.Println("\tServer << Request Headers:")
for key, val := range md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
/* server after functions */
func injectResponseHeader(ctx context.Context, md *metadata.MD, _ *metadata.MD) context.Context {
*md = metadata.Join(*md, metadata.Pairs(string(responseHDR), "has-a-value"))
return ctx
}
func displayServerResponseHeaders(ctx context.Context, md *metadata.MD, _ *metadata.MD) context.Context {
if len(*md) > 0 {
fmt.Println("\tServer >> Response Headers:")
for key, val := range *md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
func injectResponseTrailer(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
*md = metadata.Join(*md, metadata.Pairs(string(responseTRLR), "has-a-value-too"))
return ctx
}
func injectConsumedCorrelationID(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
if hdr, ok := ctx.Value(correlationID).(string); ok {
fmt.Printf("\tServer found correlationID %q in context, set consumed trailer\n", hdr)
*md = metadata.Join(*md, metadata.Pairs(string(correlationIDTRLR), hdr))
}
return ctx
}
func displayServerResponseTrailers(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
if len(*md) > 0 {
fmt.Println("\tServer >> Response Trailers:")
for key, val := range *md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
/* client after functions */
func displayClientResponseHeaders(ctx context.Context, md metadata.MD, _ metadata.MD) context.Context {
if len(md) > 0 {
fmt.Println("\tClient << Response Headers:")
for key, val := range md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
func displayClientResponseTrailers(ctx context.Context, _ metadata.MD, md metadata.MD) context.Context {
if len(md) > 0 {
fmt.Println("\tClient << Response Trailers:")
for key, val := range md {
fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
}
}
return ctx
}
func extractConsumedCorrelationID(ctx context.Context, _ metadata.MD, md metadata.MD) context.Context {
if hdr, ok := md[string(correlationIDTRLR)]; ok {
fmt.Printf("\tClient received consumed correlationID %q in metadata trailer, set context\n", hdr[len(hdr)-1])
ctx = context.WithValue(ctx, correlationIDTRLR, hdr[len(hdr)-1])
}
return ctx
}
/* CorrelationID context handlers */
func SetCorrelationID(ctx context.Context, v string) context.Context {
return context.WithValue(ctx, correlationID, v)
}
func GetConsumedCorrelationID(ctx context.Context) string {
if trlr, ok := ctx.Value(correlationIDTRLR).(string); ok {
return trlr
}
return ""
}
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