118 lines
2.6 KiB
Go
118 lines
2.6 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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"net/textproto"
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"strings"
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)
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var (
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// HeaderTopic is the header name that contains topic name
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HeaderTopic = "Micro-Topic"
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// HeaderContentType specifies content type of message
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HeaderContentType = "Content-Type"
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// HeaderEndpoint specifies endpoint in service
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HeaderEndpoint = "Micro-Endpoint"
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// HeaderService specifies service
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HeaderService = "Micro-Service"
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// HeaderTimeout specifies timeout of operation
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HeaderTimeout = "Micro-Timeout"
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// HeaderAuthorization specifies Authorization header
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HeaderAuthorization = "Authorization"
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// HeaderXRequestID specifies request id
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HeaderXRequestID = "X-Request-Id"
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)
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// Metadata is our way of representing request headers internally.
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type Metadata map[string][]string
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// Get returns value from metadata by key
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func (md Metadata) Get(key string) (string, bool) {
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// fast path
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val, ok := md[key]
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if !ok {
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// slow path
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val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
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}
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return strings.Join(val, ","), ok
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}
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// Set is used to store value in metadata
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func (md Metadata) Set(kv ...string) {
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if len(kv)%2 == 1 {
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kv = kv[:len(kv)-1]
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}
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for idx := 0; idx < len(kv); idx += 2 {
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md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = []string{kv[idx+1]}
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}
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}
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// Append is used to append value in metadata
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func (md Metadata) Append(k string, v ...string) {
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if len(v) == 0 {
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return
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}
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k = textproto.CanonicalMIMEHeaderKey(k)
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md[k] = append(md[k], v...)
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}
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// Del is used to remove value from metadata
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func (md Metadata) Del(keys ...string) {
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for _, key := range keys {
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// fast path
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delete(md, key)
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// slow path
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delete(md, textproto.CanonicalMIMEHeaderKey(key))
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}
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}
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// Copy makes a copy of the metadata
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func Copy(md Metadata) Metadata {
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nmd := make(Metadata, len(md))
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for k, v := range md {
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nmd[k] = v
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}
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return nmd
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}
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// New return new sized metadata
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func New(size int) Metadata {
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if size == 0 {
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size = 2
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}
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return make(Metadata, size)
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}
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// Merge merges metadata to existing metadata, overwriting if specified
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func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
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nmd := Copy(omd)
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for key, val := range mmd {
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nval, ok := nmd[key]
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switch {
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case ok && overwrite:
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nmd[key] = nval
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continue
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case ok && !overwrite:
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continue
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case !ok:
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for _, v := range val {
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if v != "" {
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nval = append(nval, v)
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}
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}
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nmd[key] = nval
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}
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}
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return nmd
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}
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// Pairs from which metadata created
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func Pairs(kv ...string) Metadata {
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if len(kv)%2 == 1 {
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kv = kv[:len(kv)-1]
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}
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md := make(Metadata, len(kv)/2)
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md.Set(kv...)
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return md
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}
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