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.metrics; 18 19 import com.google.auto.value.AutoValue; 20 import io.opencensus.common.ExperimentalApi; 21 import javax.annotation.Nullable; 22 import javax.annotation.concurrent.Immutable; 23 24 /** 25 * The value of a {@code Label} associated with a {@code TimeSeries}. 26 * 27 * @since 0.15 28 */ 29 @ExperimentalApi 30 @Immutable 31 @AutoValue 32 public abstract class LabelValue { 33 LabelValue()34 LabelValue() {} 35 36 /** 37 * Creates a {@link LabelValue}. 38 * 39 * @param value the value of a {@code Label}. {@code null} value indicates an unset {@code 40 * LabelValue}. 41 * @return a {@code LabelValue}. 42 * @since 0.17 43 */ create(@ullable String value)44 public static LabelValue create(@Nullable String value) { 45 return new AutoValue_LabelValue(value); 46 } 47 48 /** 49 * Returns the value of this {@link LabelValue}. Returns {@code null} if the value is unset and 50 * supposed to be ignored. 51 * 52 * @return the value. 53 * @since 0.17 54 */ 55 @Nullable getValue()56 public abstract String getValue(); 57 } 58