| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.htrace.impl; |
| |
| import org.apache.htrace.HTraceConfiguration; |
| import org.apache.htrace.Sampler; |
| |
| import java.util.Random; |
| |
| /** |
| * Sampler that returns true every N calls. |
| */ |
| public class CountSampler implements Sampler<Object> { |
| private final static String SAMPLER_FREQUENCY_CONF_KEY = "sampler.frequency"; |
| |
| final static Random random = new Random(); |
| |
| final long frequency; |
| long count = random.nextLong(); |
| |
| public CountSampler(HTraceConfiguration conf) { |
| this.frequency = Long.parseLong(conf.get(SAMPLER_FREQUENCY_CONF_KEY), 10); |
| } |
| |
| @Override |
| public boolean next(Object info) { |
| return (count++ % frequency) == 0; |
| } |
| } |