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