1 /* 2 * Copyright 2018 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.grpclb; 18 19 import com.google.common.base.Stopwatch; 20 import io.grpc.Context; 21 import io.grpc.Internal; 22 import io.grpc.LoadBalancer; 23 import io.grpc.LoadBalancerProvider; 24 import io.grpc.NameResolver.ConfigOrError; 25 import io.grpc.Status; 26 import io.grpc.grpclb.GrpclbState.Mode; 27 import io.grpc.internal.ExponentialBackoffPolicy; 28 import io.grpc.internal.JsonUtil; 29 import io.grpc.internal.ServiceConfigUtil; 30 import io.grpc.internal.ServiceConfigUtil.LbConfig; 31 import io.grpc.internal.TimeProvider; 32 import java.util.ArrayList; 33 import java.util.List; 34 import java.util.Map; 35 36 /** 37 * The provider for the "grpclb" balancing policy. This class should not be directly referenced in 38 * code. The policy should be accessed through {@link io.grpc.LoadBalancerRegistry#getProvider} 39 * with the name "grpclb". 40 */ 41 @Internal 42 public final class GrpclbLoadBalancerProvider extends LoadBalancerProvider { 43 44 private static final Mode DEFAULT_MODE = Mode.ROUND_ROBIN; 45 46 @Override isAvailable()47 public boolean isAvailable() { 48 return true; 49 } 50 51 @Override getPriority()52 public int getPriority() { 53 return 5; 54 } 55 56 @Override getPolicyName()57 public String getPolicyName() { 58 return "grpclb"; 59 } 60 61 @Override newLoadBalancer(LoadBalancer.Helper helper)62 public LoadBalancer newLoadBalancer(LoadBalancer.Helper helper) { 63 return 64 new GrpclbLoadBalancer( 65 helper, 66 Context.ROOT, 67 new CachedSubchannelPool(helper), 68 TimeProvider.SYSTEM_TIME_PROVIDER, 69 Stopwatch.createUnstarted(), 70 new ExponentialBackoffPolicy.Provider()); 71 } 72 73 @Override parseLoadBalancingPolicyConfig( Map<String, ?> rawLoadBalancingConfigPolicy)74 public ConfigOrError parseLoadBalancingPolicyConfig( 75 Map<String, ?> rawLoadBalancingConfigPolicy) { 76 try { 77 return parseLoadBalancingConfigPolicyInternal(rawLoadBalancingConfigPolicy); 78 } catch (RuntimeException e) { 79 return ConfigOrError.fromError( 80 Status.fromThrowable(e).withDescription( 81 "Failed to parse GRPCLB config: " + rawLoadBalancingConfigPolicy)); 82 } 83 } 84 parseLoadBalancingConfigPolicyInternal( Map<String, ?> rawLoadBalancingPolicyConfig)85 ConfigOrError parseLoadBalancingConfigPolicyInternal( 86 Map<String, ?> rawLoadBalancingPolicyConfig) { 87 if (rawLoadBalancingPolicyConfig == null) { 88 return ConfigOrError.fromConfig(GrpclbConfig.create(DEFAULT_MODE)); 89 } 90 String serviceName = JsonUtil.getString(rawLoadBalancingPolicyConfig, "serviceName"); 91 List<?> rawChildPolicies = JsonUtil.getList(rawLoadBalancingPolicyConfig, "childPolicy"); 92 Long initialFallbackTimeoutNs = 93 JsonUtil.getStringAsDuration(rawLoadBalancingPolicyConfig, "initialFallbackTimeout"); 94 long timeoutMs = GrpclbState.FALLBACK_TIMEOUT_MS; 95 if (initialFallbackTimeoutNs != null) { 96 timeoutMs = initialFallbackTimeoutNs / 1000000; 97 } 98 99 List<LbConfig> childPolicies = null; 100 if (rawChildPolicies != null) { 101 childPolicies = 102 ServiceConfigUtil 103 .unwrapLoadBalancingConfigList(JsonUtil.checkObjectList(rawChildPolicies)); 104 } 105 106 if (childPolicies == null || childPolicies.isEmpty()) { 107 return ConfigOrError.fromConfig( 108 GrpclbConfig.create(DEFAULT_MODE, serviceName, timeoutMs)); 109 } 110 111 List<String> policiesTried = new ArrayList<>(); 112 for (LbConfig childPolicy : childPolicies) { 113 String childPolicyName = childPolicy.getPolicyName(); 114 switch (childPolicyName) { 115 case "round_robin": 116 return ConfigOrError.fromConfig( 117 GrpclbConfig.create(Mode.ROUND_ROBIN, serviceName, timeoutMs)); 118 case "pick_first": 119 return ConfigOrError.fromConfig( 120 GrpclbConfig.create(Mode.PICK_FIRST, serviceName, timeoutMs)); 121 default: 122 policiesTried.add(childPolicyName); 123 } 124 } 125 return ConfigOrError.fromError( 126 Status 127 .UNAVAILABLE 128 .withDescription( 129 "None of " + policiesTried + " specified child policies are available.")); 130 } 131 } 132