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Alibaba Java Coding Guidelines PMD implementations(XenoAmess
TPM)
<?xml version="1.0"?>
<ruleset name="AlibabaJavaConcurrent"
xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
<description>AlibabaJavaConcurrent</description>
<rule name="ThreadPoolCreationRule"
language="java"
since="1.6"
message="java.concurrent.ThreadPoolCreationRule.rule.msg"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.ThreadPoolCreationRule">
<description>java.concurrent.ThreadPoolCreationRule.rule.desc</description>
<priority>1</priority>
<example>
<![CDATA[
Positive example 1：
//org.apache.commons.lang3.concurrent.BasicThreadFactory
ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1,
new BasicThreadFactory.Builder().namingPattern("example-schedule-pool-%d").daemon(true).build());
]]>
</example>
<example>
<![CDATA[
Positive example 2：
ThreadFactory namedThreadFactory = new ThreadFactoryBuilder()
.setNameFormat("demo-pool-%d").build();
//Common Thread Pool
ExecutorService pool = new ThreadPoolExecutor(5, 200,
0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>(1024), namedThreadFactory, new ThreadPoolExecutor.AbortPolicy());
pool.execute(()-> System.out.println(Thread.currentThread().getName()));
pool.shutdown();//gracefully shutdown
]]>
</example>
<example>
<![CDATA[
Positive example 3：
<bean id="userThreadPool"
class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="10" />
<property name="maxPoolSize" value="100" />
<property name="queueCapacity" value="2000" />
<property name="threadFactory" value= threadFactory />
<property name="rejectedExecutionHandler">
<ref local="rejectedExecutionHandler" />
</property>
</bean>
//in code
userThreadPool.execute(thread);
]]>
</example>
</rule>
<rule name="AvoidUseTimerRule"
language="java"
since="1.6"
message="java.concurrent.AvoidUseTimerRule.rule.msg"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.AvoidUseTimerRule">
<priority>1</priority>
<example>
<![CDATA[
//org.apache.commons.lang3.concurrent.BasicThreadFactory
ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1,
new BasicThreadFactory.Builder().namingPattern("example-schedule-pool-%d").daemon(true).build());
executorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
//do something
}
},initialDelay,period, TimeUnit.HOURS);
]]>
</example>
</rule>
<rule name="AvoidManuallyCreateThreadRule"
language="java"
since="1.6"
message="java.concurrent.AvoidManuallyCreateThreadRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.AvoidManuallyCreateThreadRule">
<description>java.concurrent.AvoidManuallyCreateThreadRule.rule.desc</description>
<priority>2</priority>
<example>
<![CDATA[
ThreadFactory namedThreadFactory = new ThreadFactoryBuilder()
.setNameFormat("demo-pool-%d").build();
ExecutorService singleThreadPool = new ThreadPoolExecutor(1, 1,
0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>(1024), namedThreadFactory, new ThreadPoolExecutor.AbortPolicy());
singleThreadPool.execute(()-> System.out.println(Thread.currentThread().getName()));
singleThreadPool.shutdown();
]]>
</example>
</rule>
<rule name="ThreadShouldSetNameRule"
language="java"
since="1.6"
message="java.concurrent.ThreadShouldSetNameRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.ThreadShouldSetNameRule">
<priority>2</priority>
<example>
<![CDATA[
ThreadFactory namedThreadFactory = new ThreadFactoryBuilder()
.setNameFormat("demo-pool-%d").build();
ExecutorService singleThreadPool = new ThreadPoolExecutor(1, 1,
0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>(1024), namedThreadFactory, new ThreadPoolExecutor.AbortPolicy());
singleThreadPool.execute(()-> System.out.println(Thread.currentThread().getName()));
singleThreadPool.shutdown();
]]>
</example>
<example>
<![CDATA[
public class TimerTaskThread extends Thread {
public TimerTaskThread(){
super.setName("TimerTaskThread"); …
}
]]>
</example>
</rule>
<rule name="AvoidCallStaticSimpleDateFormatRule"
language="java"
since="1.6"
message="java.concurrent.AvoidCallStaticSimpleDateFormatRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.AvoidCallStaticSimpleDateFormatRule">
<description>java.concurrent.AvoidCallStaticSimpleDateFormatRule.rule.desc</description>
<example>
<![CDATA[
Positive example 1：
private static final String FORMAT = "yyyy-MM-dd HH:mm:ss";
public String getFormat(Date date){
SimpleDateFormat dateFormat = new SimpleDateFormat(FORMAT);
return sdf.format(date);
}
]]>
</example>
<example>
<![CDATA[
Positive example 2：
private static final SimpleDateFormat SIMPLE_DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
public void getFormat(){
synchronized (sdf){
sdf.format(new Date());
….;
}
]]>
</example>
<example>
<![CDATA[
Positive example 3：
private static final ThreadLocal<DateFormat> DATE_FORMATTER = new ThreadLocal<DateFormat>() {
@Override
protected DateFormat initialValue() {
return new SimpleDateFormat("yyyy-MM-dd");
}
};
]]>
</example>
<priority>2</priority>
</rule>
<rule name="ThreadLocalShouldRemoveRule"
language="java"
since="1.6"
message="java.concurrent.ThreadLocalShouldRemoveRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.ThreadLocalShouldRemoveRule">
<priority>2</priority>
<example>
<![CDATA[
/**
* @author caikang
* @date 2017/04/07
*/
public class UserHolder {
private static final ThreadLocal<User> userThreadLocal = new ThreadLocal<User>();
public static void set(User user){
userThreadLocal.set(user);
}
public static User get(){
return userThreadLocal.get();
}
public static void remove(){
userThreadLocal.remove();
}
}
/**
* @author caikang
* @date 2017/04/07
*/
public class UserInterceptor extends HandlerInterceptorAdapter {
@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object handler) throws Exception {
UserHolder.set(new User());
return true;
}
@Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex) throws Exception {
UserHolder.remove();
}
}
]]>
</example>
</rule>
<rule name="AvoidConcurrentCompetitionRandomRule"
language="java"
since="1.6"
message="java.concurrent.AvoidConcurrentCompetitionRandomRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.AvoidConcurrentCompetitionRandomRule">
<priority>3</priority>
<example>
<![CDATA[
Positive example 1：
/**
* @author caikang
* @date 2017/04/07
*/
public class RandomInThread extends Thread {
private Random random = new Random();
@Override
public void run() {
long t = random.nextLong();
}
}
]]>
</example>
<example>
<![CDATA[
Positive example 2：
/**
* @author caikang
* @date 2017/04/07
*/
public class RandomInThread extends Thread {
private Random random = ThreadLocalRandom.current();
@Override
public void run() {
long t = random.nextLong();
}
}
]]>
</example>
</rule>
<rule name="CountDownShouldInFinallyRule"
language="java"
since="1.6"
message="java.concurrent.CountDownShouldInFinallyRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.CountDownShouldInFinallyRule">
<description>java.concurrent.CountDownShouldInFinallyRule.rule.desc</description>
<priority>3</priority>
<example>
<![CDATA[
/**
* @author caikang
* @date 2017/04/07
*/
public class CountDownExample {
public void operate(CountDownLatch countDownLatch){
try{
System.out.println("business logic");
}catch (RuntimeException e){
// do something
}finally {
countDownLatch.countDown();
}
}
}
]]>
</example>
</rule>
<rule name="LockShouldWithTryFinallyRule"
language="java"
since="1.6"
message="java.concurrent.LockShouldWithTryFinallyRule.rule.msg"
dfa="true"
class="com.alibaba.p3c.pmd.lang.java.rule.concurrent.LockShouldWithTryFinallyRule">
<description>java.concurrent.LockShouldWithTryFinallyRule.rule.desc</description>
<priority>1</priority>
<example>
<![CDATA[
Positive example：
Lock lock = new XxxLock();
// ...
lock.lock();
try {
doSomething();
doOthers();
} finally {
lock.unlock();
}
]]>
</example>
<example>
<![CDATA[
Negative example：
Lock lock = new XxxLock();
// ...
try {
// If an exception is thrown here, the finally block is executed directly
doSomething();
// The finally block executes regardless of whether the lock is successful or not
lock.lock();
doOthers();
} finally {
lock.unlock();
}
]]>
</example>
</rule>
</ruleset>