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      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.internal;
     18 
     19 import com.google.common.base.MoreObjects;
     20 import com.google.common.base.Objects;
     21 import com.google.common.collect.ImmutableSet;
     22 import io.grpc.Status.Code;
     23 import java.util.Collections;
     24 import java.util.Set;
     25 import javax.annotation.concurrent.Immutable;
     26 
     27 /**
     28  * Hedging policy data object.
     29  */
     30 @Immutable
     31 final class HedgingPolicy {
     32   final int maxAttempts;
     33   final long hedgingDelayNanos;
     34   final Set<Code> nonFatalStatusCodes;
     35 
     36   /** No hedging. */
     37   static final HedgingPolicy DEFAULT =
     38       new HedgingPolicy(1, 0, Collections.<Code>emptySet());
     39 
     40   /**
     41    * The caller is supposed to have validated the arguments and handled throwing exception or
     42    * logging warnings already, so we avoid repeating args check here.
     43    */
     44   HedgingPolicy(int maxAttempts, long hedgingDelayNanos, Set<Code> nonFatalStatusCodes) {
     45     this.maxAttempts = maxAttempts;
     46     this.hedgingDelayNanos = hedgingDelayNanos;
     47     this.nonFatalStatusCodes = ImmutableSet.copyOf(nonFatalStatusCodes);
     48   }
     49 
     50   @Override
     51   public boolean equals(Object other) {
     52     if (this == other) {
     53       return true;
     54     }
     55     if (other == null || getClass() != other.getClass()) {
     56       return false;
     57     }
     58     HedgingPolicy that = (HedgingPolicy) other;
     59     return maxAttempts == that.maxAttempts
     60         && hedgingDelayNanos == that.hedgingDelayNanos
     61         && Objects.equal(nonFatalStatusCodes, that.nonFatalStatusCodes);
     62   }
     63 
     64   @Override
     65   public int hashCode() {
     66     return Objects.hashCode(maxAttempts, hedgingDelayNanos, nonFatalStatusCodes);
     67   }
     68 
     69   @Override
     70   public String toString() {
     71     return MoreObjects.toStringHelper(this)
     72         .add("maxAttempts", maxAttempts)
     73         .add("hedgingDelayNanos", hedgingDelayNanos)
     74         .add("nonFatalStatusCodes", nonFatalStatusCodes)
     75         .toString();
     76   }
     77 
     78   /**
     79    * Provides the most suitable hedging policy for a call.
     80    */
     81   interface Provider {
     82 
     83     /**
     84      * This method is used no more than once for each call. Never returns null.
     85      */
     86     HedgingPolicy get();
     87   }
     88 }
     89