com.google.errorprone.StatisticsCollector.java Source code

Introduction

Here is the source code for com.google.errorprone.StatisticsCollector.java

Source

/*
 * Copyright 2018 The Error Prone Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.errorprone;

import com.google.common.collect.HashMultiset;
import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.Multiset;

/** A collector of counters keyed by strings. */
public interface StatisticsCollector {

    /** Adds 1 to the counter for {@code key}. */
    default void incrementCounter(String key) {
        incrementCounter(key, 1);
    }

    /** Adds {@code count} to the counter for {@code key}. */
    void incrementCounter(String key, int count);

    /** Returns a copy of the counters in this statistics collector. */
    ImmutableMultiset<String> counters();

    /** Returns a new statistics collector that will successfully count keys added to it. */
    static StatisticsCollector createCollector() {
        return new StatisticsCollector() {
            private final Multiset<String> strings = HashMultiset.create();

            @Override
            public void incrementCounter(String key, int count) {
                strings.add(key, count);
            }

            @Override
            public ImmutableMultiset<String> counters() {
                return ImmutableMultiset.copyOf(strings);
            }
        };
    }

    /**
     * Returns a statistics collector that will ignore any statistics added to it, always returning an
     * empty result for {@link #counters}.
     */
    static StatisticsCollector createNoOpCollector() {
        return new StatisticsCollector() {
            @Override
            public void incrementCounter(String key, int count) {
            }

            @Override
            public ImmutableMultiset<String> counters() {
                return ImmutableMultiset.of();
            }
        };
    }
}