forked from TrueCloudLab/distribution
138 lines
4.1 KiB
Go
138 lines
4.1 KiB
Go
/*
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*
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* Copyright 2021 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 resolver
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type addressMapEntry struct {
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addr Address
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value interface{}
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}
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// AddressMap is a map of addresses to arbitrary values taking into account
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// Attributes. BalancerAttributes are ignored, as are Metadata and Type.
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// Multiple accesses may not be performed concurrently. Must be created via
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// NewAddressMap; do not construct directly.
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type AddressMap struct {
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// The underlying map is keyed by an Address with fields that we don't care
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// about being set to their zero values. The only fields that we care about
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// are `Addr`, `ServerName` and `Attributes`. Since we need to be able to
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// distinguish between addresses with same `Addr` and `ServerName`, but
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// different `Attributes`, we cannot store the `Attributes` in the map key.
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//
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// The comparison operation for structs work as follows:
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// Struct values are comparable if all their fields are comparable. Two
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// struct values are equal if their corresponding non-blank fields are equal.
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//
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// The value type of the map contains a slice of addresses which match the key
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// in their `Addr` and `ServerName` fields and contain the corresponding value
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// associated with them.
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m map[Address]addressMapEntryList
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}
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func toMapKey(addr *Address) Address {
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return Address{Addr: addr.Addr, ServerName: addr.ServerName}
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}
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type addressMapEntryList []*addressMapEntry
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// NewAddressMap creates a new AddressMap.
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func NewAddressMap() *AddressMap {
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return &AddressMap{m: make(map[Address]addressMapEntryList)}
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}
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// find returns the index of addr in the addressMapEntry slice, or -1 if not
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// present.
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func (l addressMapEntryList) find(addr Address) int {
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for i, entry := range l {
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// Attributes are the only thing to match on here, since `Addr` and
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// `ServerName` are already equal.
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if entry.addr.Attributes.Equal(addr.Attributes) {
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return i
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}
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}
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return -1
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}
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// Get returns the value for the address in the map, if present.
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func (a *AddressMap) Get(addr Address) (value interface{}, ok bool) {
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addrKey := toMapKey(&addr)
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entryList := a.m[addrKey]
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if entry := entryList.find(addr); entry != -1 {
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return entryList[entry].value, true
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}
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return nil, false
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}
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// Set updates or adds the value to the address in the map.
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func (a *AddressMap) Set(addr Address, value interface{}) {
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addrKey := toMapKey(&addr)
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entryList := a.m[addrKey]
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if entry := entryList.find(addr); entry != -1 {
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entryList[entry].value = value
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return
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}
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a.m[addrKey] = append(entryList, &addressMapEntry{addr: addr, value: value})
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}
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// Delete removes addr from the map.
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func (a *AddressMap) Delete(addr Address) {
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addrKey := toMapKey(&addr)
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entryList := a.m[addrKey]
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entry := entryList.find(addr)
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if entry == -1 {
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return
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}
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if len(entryList) == 1 {
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entryList = nil
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} else {
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copy(entryList[entry:], entryList[entry+1:])
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entryList = entryList[:len(entryList)-1]
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}
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a.m[addrKey] = entryList
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}
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// Len returns the number of entries in the map.
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func (a *AddressMap) Len() int {
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ret := 0
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for _, entryList := range a.m {
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ret += len(entryList)
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}
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return ret
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}
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// Keys returns a slice of all current map keys.
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func (a *AddressMap) Keys() []Address {
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ret := make([]Address, 0, a.Len())
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for _, entryList := range a.m {
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for _, entry := range entryList {
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ret = append(ret, entry.addr)
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}
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}
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return ret
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}
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// Values returns a slice of all current map values.
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func (a *AddressMap) Values() []interface{} {
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ret := make([]interface{}, 0, a.Len())
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for _, entryList := range a.m {
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for _, entry := range entryList {
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ret = append(ret, entry.value)
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}
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}
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return ret
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}
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