1 /* 2 * Copyright 2020 The gRPC Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.grpc.xds; 18 19 import static com.google.common.base.Preconditions.checkNotNull; 20 21 import io.grpc.Attributes; 22 import io.grpc.EquivalentAddressGroup; 23 import io.grpc.NameResolver.ResolutionResultAttr; 24 import java.util.ArrayList; 25 import java.util.Collections; 26 import java.util.List; 27 import javax.annotation.Nullable; 28 29 final class AddressFilter { 30 @ResolutionResultAttr 31 private static final Attributes.Key<PathChain> PATH_CHAIN_KEY = 32 Attributes.Key.create("io.grpc.xds.AddressFilter.PATH_CHAIN_KEY"); 33 34 // Prevent instantiation. AddressFilter()35 private AddressFilter() {} 36 37 /** 38 * Returns a new EquivalentAddressGroup by setting a path filter to the given 39 * EquivalentAddressGroup. This method does not modify the input address. 40 */ setPathFilter(EquivalentAddressGroup address, List<String> names)41 static EquivalentAddressGroup setPathFilter(EquivalentAddressGroup address, List<String> names) { 42 checkNotNull(address, "address"); 43 checkNotNull(names, "names"); 44 Attributes.Builder attrBuilder = address.getAttributes().toBuilder().discard(PATH_CHAIN_KEY); 45 PathChain pathChain = null; 46 for (String name : names) { 47 if (pathChain == null) { 48 pathChain = new PathChain(name); 49 attrBuilder.set(PATH_CHAIN_KEY, pathChain); 50 } else { 51 pathChain.next = new PathChain(name); 52 } 53 } 54 return new EquivalentAddressGroup(address.getAddresses(), attrBuilder.build()); 55 } 56 57 /** 58 * Returns the next level hierarchical addresses derived from the given hierarchical addresses 59 * with the given filter name (any non-hierarchical addresses in the input will be ignored). 60 * This method does not modify the input addresses. 61 */ filter(List<EquivalentAddressGroup> addresses, String name)62 static List<EquivalentAddressGroup> filter(List<EquivalentAddressGroup> addresses, String name) { 63 checkNotNull(addresses, "addresses"); 64 checkNotNull(name, "name"); 65 List<EquivalentAddressGroup> filteredAddresses = new ArrayList<>(); 66 for (EquivalentAddressGroup address : addresses) { 67 PathChain pathChain = address.getAttributes().get(PATH_CHAIN_KEY); 68 if (pathChain != null && pathChain.name.equals(name)) { 69 Attributes filteredAddressAttrs = 70 address.getAttributes().toBuilder().set(PATH_CHAIN_KEY, pathChain.next).build(); 71 filteredAddresses.add( 72 new EquivalentAddressGroup(address.getAddresses(), filteredAddressAttrs)); 73 } 74 } 75 return Collections.unmodifiableList(filteredAddresses); 76 } 77 78 private static final class PathChain { 79 final String name; 80 @Nullable PathChain next; 81 PathChain(String name)82 PathChain(String name) { 83 this.name = checkNotNull(name, "name"); 84 } 85 86 @Override toString()87 public String toString() { 88 return name + (next == null ? "" : ", " + next); 89 } 90 } 91 } 92