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/*
*
* Copyright 2020 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
// Package hierarchy contains functions to set and get hierarchy string from
// addresses.
//
// This package is experimental.
package hierarchy
import (
"google.golang.org/grpc/resolver"
)
type pathKeyType string
const pathKey = pathKeyType("grpc.internal.address.hierarchical_path")
type pathValue []string
func (p pathValue) Equal(o interface{}) bool {
op, ok := o.(pathValue)
if !ok {
return false
}
if len(op) != len(p) {
return false
}
for i, v := range p {
if v != op[i] {
return false
}
}
return true
}
// Get returns the hierarchical path of addr.
func Get(addr resolver.Address) []string {
attrs := addr.BalancerAttributes
if attrs == nil {
return nil
}
path, _ := attrs.Value(pathKey).(pathValue)
return ([]string)(path)
}
// Set overrides the hierarchical path in addr with path.
func Set(addr resolver.Address, path []string) resolver.Address {
addr.BalancerAttributes = addr.BalancerAttributes.WithValue(pathKey, pathValue(path))
return addr
}
// Group splits a slice of addresses into groups based on
// the first hierarchy path. The first hierarchy path will be removed from the
// result.
//
// Input:
// [
//
// {addr0, path: [p0, wt0]}
// {addr1, path: [p0, wt1]}
// {addr2, path: [p1, wt2]}
// {addr3, path: [p1, wt3]}
//
// ]
//
// Addresses will be split into p0/p1, and the p0/p1 will be removed from the
// path.
//
// Output:
//
// {
// p0: [
// {addr0, path: [wt0]},
// {addr1, path: [wt1]},
// ],
// p1: [
// {addr2, path: [wt2]},
// {addr3, path: [wt3]},
// ],
// }
//
// If hierarchical path is not set, or has no path in it, the address is
// dropped.
func Group(addrs []resolver.Address) map[string][]resolver.Address {
ret := make(map[string][]resolver.Address)
for _, addr := range addrs {
oldPath := Get(addr)
if len(oldPath) == 0 {
continue
}
curPath := oldPath[0]
newPath := oldPath[1:]
newAddr := Set(addr, newPath)
ret[curPath] = append(ret[curPath], newAddr)
}
return ret
}
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