cubefs

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/*
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 *
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 * Copyright 2020 gRPC authors.
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 *
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 */
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// Package metadata contains functions to set and get metadata from addresses.
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//
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// This package is experimental.
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package metadata
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import (
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	"google.golang.org/grpc/metadata"
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	"google.golang.org/grpc/resolver"
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)
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type mdKeyType string
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const mdKey = mdKeyType("grpc.internal.address.metadata")
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// Get returns the metadata of addr.
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func Get(addr resolver.Address) metadata.MD {
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	attrs := addr.Attributes
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	if attrs == nil {
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		return nil
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	}
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	md, _ := attrs.Value(mdKey).(metadata.MD)
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	return md
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}
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// Set sets (overrides) the metadata in addr.
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//
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// When a SubConn is created with this address, the RPCs sent on it will all
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// have this metadata.
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func Set(addr resolver.Address, md metadata.MD) resolver.Address {
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	addr.Attributes = addr.Attributes.WithValues(mdKey, md)
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	return addr
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}
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