130 lines
2.5 KiB
Go
130 lines
2.5 KiB
Go
// Package metadata is a way of defining message headers
|
|
package metadata
|
|
|
|
import (
|
|
"net/textproto"
|
|
"sort"
|
|
)
|
|
|
|
var (
|
|
// HeaderPrefix for all headers passed
|
|
HeaderPrefix = "Micro-"
|
|
)
|
|
|
|
// 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
|
|
|
|
type rawMetadata struct {
|
|
md Metadata
|
|
}
|
|
|
|
var (
|
|
// defaultMetadataSize used when need to init new Metadata
|
|
defaultMetadataSize = 2
|
|
)
|
|
|
|
// Iterator used to iterate over metadata with order
|
|
type Iterator struct {
|
|
cur int
|
|
cnt int
|
|
keys []string
|
|
md Metadata
|
|
}
|
|
|
|
// Next advance iterator to next element
|
|
func (iter *Iterator) Next(k, v *string) bool {
|
|
if iter.cur+1 > iter.cnt {
|
|
return false
|
|
}
|
|
|
|
*k = iter.keys[iter.cur]
|
|
*v = iter.md[*k]
|
|
iter.cur++
|
|
return true
|
|
}
|
|
|
|
// Iterator returns the itarator for metadata in sorted order
|
|
func (md Metadata) Iterator() *Iterator {
|
|
iter := &Iterator{md: md, cnt: len(md)}
|
|
iter.keys = make([]string, 0, iter.cnt)
|
|
for k := range md {
|
|
iter.keys = append(iter.keys, k)
|
|
}
|
|
sort.Strings(iter.keys)
|
|
return iter
|
|
}
|
|
|
|
// Get returns value from metadata by key
|
|
func (md Metadata) Get(key string) (string, bool) {
|
|
// fast path
|
|
val, ok := md[key]
|
|
if !ok {
|
|
// slow path
|
|
val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
|
|
}
|
|
return val, ok
|
|
}
|
|
|
|
// Set is used to store value in metadata
|
|
func (md Metadata) Set(key, val string) {
|
|
md[textproto.CanonicalMIMEHeaderKey(key)] = val
|
|
}
|
|
|
|
// Del is used to remove value from metadata
|
|
func (md Metadata) Del(key string) {
|
|
// fast path
|
|
delete(md, key)
|
|
// slow path
|
|
delete(md, textproto.CanonicalMIMEHeaderKey(key))
|
|
}
|
|
|
|
// Copy makes a copy of the metadata
|
|
func Copy(md Metadata) Metadata {
|
|
nmd := New(len(md))
|
|
for key, val := range md {
|
|
nmd.Set(key, val)
|
|
}
|
|
return nmd
|
|
}
|
|
|
|
// New return new sized metadata
|
|
func New(size int) Metadata {
|
|
if size == 0 {
|
|
size = defaultMetadataSize
|
|
}
|
|
return make(Metadata, size)
|
|
}
|
|
|
|
// Merge merges metadata to existing metadata, overwriting if specified
|
|
func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
|
|
nmd := Copy(omd)
|
|
for key, val := range mmd {
|
|
if _, ok := nmd[key]; ok && !overwrite {
|
|
// skip
|
|
} else if val != "" {
|
|
nmd.Set(key, val)
|
|
} else {
|
|
nmd.Del(key)
|
|
}
|
|
}
|
|
return nmd
|
|
}
|
|
|
|
func Pairs(kv ...string) (Metadata, bool) {
|
|
if len(kv)%2 == 1 {
|
|
return nil, false
|
|
}
|
|
md := New(len(kv) / 2)
|
|
var k string
|
|
for i, v := range kv {
|
|
if i%2 == 0 {
|
|
k = v
|
|
continue
|
|
}
|
|
md.Set(k, v)
|
|
}
|
|
return md, true
|
|
}
|