104 lines
2.6 KiB
104 lines
2.6 KiB
package metadata |
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import ( |
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"context" |
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"fmt" |
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"strings" |
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) |
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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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// New creates an MD from a given key-values map. |
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func New(mds ...map[string]string) Metadata { |
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md := Metadata{} |
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for _, m := range mds { |
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for k, v := range m { |
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md.Set(k, v) |
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} |
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} |
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return md |
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} |
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// Get returns the value associated with the passed key. |
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func (m Metadata) Get(key string) string { |
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return m[strings.ToLower(key)] |
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} |
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// Set stores the key-value pair. |
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func (m Metadata) Set(key string, value string) { |
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if key == "" || value == "" { |
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return |
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} |
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m[strings.ToLower(key)] = value |
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} |
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// Range iterate over element in metadata. |
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func (m Metadata) Range(f func(k, v string) bool) { |
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for k, v := range m { |
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if !f(k, v) { |
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break |
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} |
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} |
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} |
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// Clone returns a deep copy of Metadata |
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func (m Metadata) Clone() Metadata { |
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md := make(Metadata, len(m)) |
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for k, v := range m { |
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md[k] = v |
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} |
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return md |
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} |
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type serverMetadataKey struct{} |
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// NewServerContext creates a new context with client md attached. |
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func NewServerContext(ctx context.Context, md Metadata) context.Context { |
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return context.WithValue(ctx, serverMetadataKey{}, md) |
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} |
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// FromServerContext returns the server metadata in ctx if it exists. |
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func FromServerContext(ctx context.Context) (Metadata, bool) { |
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md, ok := ctx.Value(serverMetadataKey{}).(Metadata) |
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return md, ok |
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} |
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type clientMetadataKey struct{} |
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// NewClientContext creates a new context with client md attached. |
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func NewClientContext(ctx context.Context, md Metadata) context.Context { |
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return context.WithValue(ctx, clientMetadataKey{}, md) |
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} |
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// FromClientContext returns the client metadata in ctx if it exists. |
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func FromClientContext(ctx context.Context) (Metadata, bool) { |
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md, ok := ctx.Value(clientMetadataKey{}).(Metadata) |
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return md, ok |
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} |
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// AppendToClientContext returns a new context with the provided kv merged |
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// with any existing metadata in the context. |
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func AppendToClientContext(ctx context.Context, kv ...string) context.Context { |
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if len(kv)%2 == 1 { |
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panic(fmt.Sprintf("metadata: AppendToClientContext got an odd number of input pairs for metadata: %d", len(kv))) |
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} |
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md, _ := FromClientContext(ctx) |
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md = md.Clone() |
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for i := 0; i < len(kv); i += 2 { |
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md.Set(kv[i], kv[i+1]) |
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} |
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return NewClientContext(ctx, md) |
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} |
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// MergeToClientContext merge new metadata into ctx. |
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func MergeToClientContext(ctx context.Context, cmd Metadata) context.Context { |
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md, _ := FromClientContext(ctx) |
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md = md.Clone() |
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for k, v := range cmd { |
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md[k] = v |
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} |
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return NewClientContext(ctx, md) |
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}
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