checkstyle.xml

<?xml version="1.0"?>
<!--
  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.
-->
<!DOCTYPE module PUBLIC
          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
          "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
  <property name="severity" value="error"/>

  <property name="fileExtensions" value="java, properties, xml"/>

  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

  <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
  <!-- this exists only because for some reason the comment filter does not seem to work for Semaphore -->
  <module name="SuppressionFilter">
    <property name="file" value="${checkstyle.suppressions}"
              default="checkstyle-suppressions.xml" />
    <property name="optional" value="false"/>
  </module>

  <module name="TreeWalker">
    <module name="SuppressWithNearbyCommentFilter">
       <property name="commentFormat" value="checkstyle: permit this import"/>
       <property name="checkFormat" value="IllegalImport"/>
       <property name="influenceFormat" value="0"/>
    </module>
 
    <module name="SuppressWithNearbyCommentFilter">
       <property name="commentFormat" value="checkstyle: permit this instantiation"/>
       <property name="checkFormat" value="IllegalInstantiation"/>
       <property name="influenceFormat" value="0"/>
    </module>
 
    <module name="SuppressWithNearbyCommentFilter">
       <property name="commentFormat" value="checkstyle: permit system clock"/>
       <property name="idFormat" value="blockSystemClock"/>
       <property name="influenceFormat" value="0"/>
    </module>

    <module name="SuppressWithNearbyCommentFilter">
      <property name="commentFormat" value="checkstyle: permit this invocation"/>
      <property name="idFormat" value="blockPathToFile"/>
      <property name="influenceFormat" value="0"/>
    </module>
 
    <module name="RegexpSinglelineJava">
      <!-- block system time -->
      <property name="id" value="blockSystemClock"/>
      <property name="format" value="System\.(currentTimeMillis|nanoTime)"/>
      <property name="ignoreComments" value="true"/>
      <property name="message" value="Avoid System for time, should use org.apache.cassandra.utils.Clock.Global or org.apache.cassandra.utils.Clock interface" />
    </module>

    <module name="RegexpSinglelineJava">
      <!-- block Instant.now -->
      <property name="id" value="blockInstantNow"/>
      <property name="format" value="Instant\.now"/>
      <property name="ignoreComments" value="true"/>
      <property name="message" value="Avoid Instant.now() for time, should use org.apache.cassandra.util.FBUtilities.now()" />
    </module>

    <module name="RegexpSinglelineJava">
      <!-- block normal executors -->
      <property name="id" value="blockExecutors"/>
      <property name="format" value="newSingleThreadExecutor|newFixedThreadPool|newCachedThreadPool|newSingleThreadScheduledExecutor|newWorkStealingPool|newScheduledThreadPool|defaultThreadFactory"/>
      <property name="ignoreComments" value="true"/>
      <property name="message" value="Avoid creating an executor directly, should use org.apache.cassandra.concurrent.ExecutorFactory.Global#executorFactory" />
    </module>
    <module name="RegexpSinglelineJava">
      <!-- block guavas directExecutor -->
      <property name="id" value="blockGuavaDirectExecutor"/>
      <property name="format" value="MoreExecutors\.directExecutor"/>
      <property name="ignoreComments" value="true"/>
      <property name="message" value="Avoid MoreExecutors.directExecutor() in favor of ImmediateExecutor.INSTANCE" />
    </module>
    <module name="IllegalImport">
      <property name="illegalPkgs" value="junit.framework"/>
      <property name="illegalClasses" value="java.io.File,java.io.FileInputStream,java.io.FileOutputStream,java.io.FileReader,java.io.FileWriter,java.io.RandomAccessFile,java.util.concurrent.Semaphore,java.util.concurrent.CountDownLatch,java.util.concurrent.Executors,java.util.concurrent.LinkedBlockingQueue,java.util.concurrent.SynchronousQueue,java.util.concurrent.ArrayBlockingQueue,com.google.common.util.concurrent.Futures,java.util.concurrent.CompletableFuture,io.netty.util.concurrent.Future,io.netty.util.concurrent.Promise,io.netty.util.concurrent.AbstractFuture,com.google.common.util.concurrent.ListenableFutureTask,com.google.common.util.concurrent.ListenableFuture,com.google.common.util.concurrent.AbstractFuture"/>
    </module>
    <module name="IllegalInstantiation">
      <property name="classes" value="java.io.File,java.lang.Thread,java.util.concurrent.FutureTask,java.util.concurrent.Semaphore,java.util.concurrent.CountDownLatch,java.util.concurrent.ScheduledThreadPoolExecutor,java.util.concurrent.ThreadPoolExecutor,java.util.concurrent.ForkJoinPool,java.lang.OutOfMemoryError"/>
    </module>

    <module name="RegexpSinglelineJava">
      <!-- block Path#toFile() -->
      <property name="id" value="blockPathToFile"/>
      <property name="format" value="toFile\(\)"/>
      <property name="message" value="Avoid Path#toFile(), as some implementations may not support it." />
    </module>

    <module name="RedundantImport"/>
    <module name="UnusedImports"/>
  </module>

</module>