| /* |
| * 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.cassandra.service.reads; |
| |
| import java.text.DecimalFormat; |
| import java.text.DecimalFormatSymbols; |
| import java.util.Locale; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| |
| import com.google.common.base.Objects; |
| |
| import com.codahale.metrics.Snapshot; |
| import org.apache.cassandra.exceptions.ConfigurationException; |
| import org.apache.cassandra.metrics.SnapshottingTimer; |
| import org.apache.cassandra.schema.TableParams; |
| |
| public class PercentileSpeculativeRetryPolicy implements SpeculativeRetryPolicy |
| { |
| public static final PercentileSpeculativeRetryPolicy NINETY_NINE_P = new PercentileSpeculativeRetryPolicy(99.0); |
| |
| private static final Pattern PATTERN = Pattern.compile("^(?<val>[0-9.]+)p(ercentile)?$", Pattern.CASE_INSENSITIVE); |
| /** |
| * The pattern above uses dot as decimal separator, so we use {@link Locale#ENGLISH} to enforce that. (CASSANDRA-14374) |
| */ |
| private static final DecimalFormat FORMATTER = new DecimalFormat("#.####", new DecimalFormatSymbols(Locale.ENGLISH)); |
| |
| private final double percentile; |
| |
| public PercentileSpeculativeRetryPolicy(double percentile) |
| { |
| this.percentile = percentile; |
| } |
| |
| @Override |
| public long calculateThreshold(SnapshottingTimer latency, long existingValue) |
| { |
| return calculateThreshold(latency.getPercentileSnapshot(), existingValue); |
| } |
| |
| public long calculateThreshold(Snapshot snapshot, long existingValue) |
| { |
| if (snapshot.size() <= 0) |
| return existingValue; |
| // latency snapshot uses a default timer so is in microseconds, so just return percentile |
| return (long) snapshot.getValue(percentile / 100); |
| } |
| |
| @Override |
| public Kind kind() |
| { |
| return Kind.PERCENTILE; |
| } |
| |
| @Override |
| public boolean equals(Object obj) |
| { |
| if (!(obj instanceof PercentileSpeculativeRetryPolicy)) |
| return false; |
| PercentileSpeculativeRetryPolicy rhs = (PercentileSpeculativeRetryPolicy) obj; |
| return percentile == rhs.percentile; |
| } |
| |
| @Override |
| public int hashCode() |
| { |
| return Objects.hashCode(kind(), percentile); |
| } |
| |
| @Override |
| public String toString() |
| { |
| return String.format("%sp", FORMATTER.format(percentile)); |
| } |
| |
| static PercentileSpeculativeRetryPolicy fromString(String str) |
| { |
| Matcher matcher = PATTERN.matcher(str); |
| |
| if (!matcher.matches()) |
| throw new IllegalArgumentException(); |
| |
| String val = matcher.group("val"); |
| |
| double percentile; |
| try |
| { |
| percentile = Double.parseDouble(val); |
| } |
| catch (IllegalArgumentException e) |
| { |
| throw new ConfigurationException(String.format("Invalid value %s for option '%s'", str, TableParams.Option.SPECULATIVE_RETRY)); |
| } |
| |
| if (percentile <= 0.0 || percentile >= 100.0) |
| { |
| throw new ConfigurationException(String.format("Invalid value %s for PERCENTILE option '%s': must be between (0.0 and 100.0)", |
| str, TableParams.Option.SPECULATIVE_RETRY)); |
| } |
| |
| return new PercentileSpeculativeRetryPolicy(percentile); |
| } |
| |
| static boolean stringMatches(String str) |
| { |
| return PATTERN.matcher(str).matches(); |
| } |
| } |