83 lines
1.8 KiB
Go
83 lines
1.8 KiB
Go
// Package metadata is a way of defining message headers
|
|
package metadata
|
|
|
|
import (
|
|
"context"
|
|
"strings"
|
|
)
|
|
|
|
type metaKey struct{}
|
|
|
|
// Metadata is our way of representing request headers internally.
|
|
// They're used at the RPC level and translate back and forth
|
|
// from Transport headers.
|
|
type Metadata map[string]string
|
|
|
|
// Copy makes a copy of the metadata
|
|
func Copy(md Metadata) Metadata {
|
|
cmd := make(Metadata)
|
|
for k, v := range md {
|
|
cmd[k] = v
|
|
}
|
|
return cmd
|
|
}
|
|
|
|
// Get returns a single value from metadata in the context
|
|
func Get(ctx context.Context, key string) (string, bool) {
|
|
md, ok := FromContext(ctx)
|
|
if !ok {
|
|
return "", ok
|
|
}
|
|
// attempt to get as is
|
|
val, ok := md[key]
|
|
if ok {
|
|
return val, ok
|
|
}
|
|
|
|
// attempt to get lower case
|
|
val, ok = md[strings.Title(key)]
|
|
|
|
return val, ok
|
|
}
|
|
|
|
// FromContext returns metadata from the given context
|
|
func FromContext(ctx context.Context) (Metadata, bool) {
|
|
md, ok := ctx.Value(metaKey{}).(Metadata)
|
|
if !ok {
|
|
return nil, ok
|
|
}
|
|
|
|
// capitalise all values
|
|
newMD := make(map[string]string)
|
|
for k, v := range md {
|
|
newMD[strings.Title(k)] = v
|
|
}
|
|
|
|
return newMD, ok
|
|
}
|
|
|
|
// NewContext creates a new context with the given metadata
|
|
func NewContext(ctx context.Context, md Metadata) context.Context {
|
|
return context.WithValue(ctx, metaKey{}, md)
|
|
}
|
|
|
|
// MergeContext merges metadata to existing metadata, overwriting if specified
|
|
func MergeContext(ctx context.Context, patchMd Metadata, overwrite bool) context.Context {
|
|
if ctx == nil {
|
|
ctx = context.Background()
|
|
}
|
|
md, _ := ctx.Value(metaKey{}).(Metadata)
|
|
cmd := make(Metadata)
|
|
for k, v := range md {
|
|
cmd[k] = v
|
|
}
|
|
for k, v := range patchMd {
|
|
if _, ok := cmd[k]; ok && !overwrite {
|
|
// skip
|
|
} else {
|
|
cmd[k] = v
|
|
}
|
|
}
|
|
return context.WithValue(ctx, metaKey{}, cmd)
|
|
}
|