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      1 /*
      2  * Copyright 2018, OpenCensus 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.opencensus.common;
     18 
     19 import com.google.auto.value.AutoValue;
     20 import javax.annotation.concurrent.Immutable;
     21 
     22 /**
     23  * A representation of stats measured on the server side.
     24  *
     25  * @since 0.16
     26  */
     27 @Immutable
     28 @AutoValue
     29 public abstract class ServerStats {
     30 
     31   ServerStats() {}
     32 
     33   /**
     34    * Returns Load Balancer latency, a latency observed at Load Balancer.
     35    *
     36    * @return Load Balancer latency in nanoseconds.
     37    * @since 0.16
     38    */
     39   public abstract long getLbLatencyNs();
     40 
     41   /**
     42    * Returns Service latency, a latency observed at Server.
     43    *
     44    * @return Service latency in nanoseconds.
     45    * @since 0.16
     46    */
     47   public abstract long getServiceLatencyNs();
     48 
     49   /**
     50    * Returns Trace options, a set of bits indicating properties of trace.
     51    *
     52    * @return Trace options a set of bits indicating properties of trace.
     53    * @since 0.16
     54    */
     55   public abstract byte getTraceOption();
     56 
     57   /**
     58    * Creates new {@link ServerStats} from specified parameters.
     59    *
     60    * @param lbLatencyNs Represents request processing latency observed on Load Balancer. It is
     61    *     measured in nanoseconds. Must not be less than 0. Value of 0 represents that the latency is
     62    *     not measured.
     63    * @param serviceLatencyNs Represents request processing latency observed on Server. It is
     64    *     measured in nanoseconds. Must not be less than 0. Value of 0 represents that the latency is
     65    *     not measured.
     66    * @param traceOption Represents set of bits to indicate properties of trace. Currently it used
     67    *     only the least signification bit to represent sampling of the request on the server side.
     68    *     Other bits are ignored.
     69    * @return new {@code ServerStats} with specified fields.
     70    * @throws IllegalArgumentException if the arguments are out of range.
     71    * @since 0.16
     72    */
     73   public static ServerStats create(long lbLatencyNs, long serviceLatencyNs, byte traceOption) {
     74 
     75     if (lbLatencyNs < 0) {
     76       throw new IllegalArgumentException("'getLbLatencyNs' is less than zero: " + lbLatencyNs);
     77     }
     78 
     79     if (serviceLatencyNs < 0) {
     80       throw new IllegalArgumentException(
     81           "'getServiceLatencyNs' is less than zero: " + serviceLatencyNs);
     82     }
     83 
     84     return new AutoValue_ServerStats(lbLatencyNs, serviceLatencyNs, traceOption);
     85   }
     86 }
     87