AsynchronousCommandExecutor.java
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net.sf.ehcache.constructs.asynchronous |
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ehcache |
View: Reasons, Metrics, Source Code
These are the metrics that contribute to the Enerjy Score for this file, ranked by impact. So the metrics listed at the top influence the score to a greater extent that the metrics listed at the bottom.
| Metric | Description | |
|---|---|---|
| JAVA0143 | JAVA0143 Synchronized method |  |
| DECL_COMMENTS | Comments in declarations | |
| SIZE | Size of the file in bytes | |
| DOC_COMMENT | Number of javadoc comment lines | |
| RETURNS | Number of return points from functions | |
| BLOCKS | Number of blocks | |
| JAVA0034 | JAVA0034 Missing braces in if statement | |
| EXITS | Procedure exits | |
| JAVA0166 | JAVA0166 Generic exception caught | |
| JAVA0285 | JAVA0285 Dereference of potentially null variable | |
| COMMENTS | Comment lines | |
| JAVA0177 | JAVA0177 Variable declaration missing initializer | |
| LINES | Number of lines in the source file | |
| PROGRAM_VOCAB | Halstead program vocabulary | |
| CYCLOMATIC | Cyclomatic complexity | |
| UNIQUE_OPERANDS | Number of unique operands | |
| INTERFACE_COMPLEXITY | Interface complexity | |
| JAVA0126 | JAVA0126 Method declares unchecked exception in throws | |
| JAVA0130 | JAVA0130 Non-static method does not use instance fields | |
| ELOC | Effective lines of code | |
| LOC | Lines of code | |
| LOGICAL_LINES | Number of statements | |
| OPERATORS | Number of operators | |
| FUNCTIONS | Number of function declarations | |
| UNIQUE_OPERATORS | Number of unique operators | |
| JAVA0128 | JAVA0128 Public constructor in non-public class | |
| PROGRAM_VOLUME | Halstead program volume | |
| PROGRAM_LENGTH | Halstead program length | |
| JAVA0110 | JAVA0110 Incorrect javadoc: no @return tag | |
| JAVA0264 | JAVA0264 Integer math in long context - check for overflow | |
| JAVA0087 | JAVA0087 Use of Thread.sleep() | |
| JAVA0117 | JAVA0117 Missing javadoc: method 'method' | |
| JAVA0108 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| OPERANDS | Number of operands | |
| JAVA0068 | JAVA0068 Modifiers not declared in recommended order | |
| JAVA0270 | JAVA0270 Use Java 5.0 enhanced for loop construct to iterate over all elements in an array | |
| NEST_DEPTH | Maximum nesting depth | |
| JAVA0145 | JAVA0145 Tab character used in source file | |
/**
* Copyright 2003-2008 Luck Consulting Pty Ltd
*
* 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 net.sf.ehcache.constructs.asynchronous;
import net.sf.ehcache.CacheException;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import java.io.Serializable;
import java.rmi.dgc.VMID;
import java.util.Date;
import java.util.Stack;
import java.util.Queue;
import java.util.logging.Logger;
import java.util.logging.Level;
import java.util.concurrent.ConcurrentLinkedQueue;
/**
* Handles the asynchronous execution of commands. This class contains subtle threading interactions and should
* not be modified without comprehensive multi-threaded tests.
* <p/>
* AsynchronousCommandExecutor is a singleton. Multiple clients may use it. It will execute commands in the order they were
* added per client. To preserve order, if a command cannot be executed, all commands will wait behind it.
* <p/>
* This code requires JDK1.5 at present.
* @author <a href="mailto:gluck@thoughtworks.com">Greg Luck</a>
* @version $Id: AsynchronousCommandExecutor.java 744 2008-08-16 20:10:49Z gregluck $
*/
public final class AsynchronousCommandExecutor {
/**
* The name of the message cache in the ehcache.xml configuration file.
*/
public static final String MESSAGE_CACHE = "net.sf.ehcache.constructs.asynchronous.MessageCache";
/**
* The command completed successfully
*/
public static final String SUCCESSFUL_EXECUTION = "Successful execution";
/**
* The dispatcher thread interval. It wakes up the dispatcher thread and attempts to process commands in the cache.
* Commands will ignore the execution request if they have a set time between retries. New messages dispatched, will
* also cause commands to be attempted immediately.
* <p/>
* Setting this to a low value will cause high cpu load. The recommended value is the amount of time between failed
* message retries, which by default is 1 minute.
*/
public static final int DEFAULT_DISPATCHER_THREAD_INTERVAL_SECONDS = 60;
/**
* Minimum setting for the dispatcher thread interval.
*
* @see #DEFAULT_DISPATCHER_THREAD_INTERVAL_SECONDS
*/
public static final int MINIMUM_SAFE_DISPATCHER_THREAD_INTERVAL = 30;
/**
* The messageCache contains {@link Command} element values, and a queue that maintains their order.
* This is the key of the queue element.
*/
public static final String QUEUE_KEY = "QueueKey";
private static final long WAIT_FOR_THREAD_INITIALIZATION = 5;
private static final Logger LOG = Logger.getLogger(AsynchronousCommandExecutor.class.getName());
private static final int MS_PER_SECOND = 1000;
private static AsynchronousCommandExecutor singleton;
private static CacheManager cacheManager;
private boolean active;
private Thread dispatcherThread;
/**
* The thread interval in seconds. Do not set this to 0 or too small a value or CPU usage will skyrocket.
*/
private long dispatcherThreadIntervalSeconds;
private AsynchronousCommandExecutor() throws CacheException {
cacheManager = CacheManager.getInstance();
addShutdownHook();
active = true;
dispatcherThreadIntervalSeconds = DEFAULT_DISPATCHER_THREAD_INTERVAL_SECONDS;
dispatcherThread = new DispatcherThread();
dispatcherThread.start();
//wait for all the threads to initialize. Without this, if a command is immediately queued the notifyAll
//on queueForExecution, the despatcher thread is not ready to receive it.
try {
Thread.sleep(WAIT_FOR_THREAD_INITIALIZATION);
} catch (InterruptedException e) {
LOG.log(Level.WARNING, "Interrupted while initiliazing", e);
}
}
/**
* Factory method to get an instance of MessageDispatcher.
*
* @return a fully initialized reference to the singleton.
* @throws AsynchronousCommandException
*/
public static synchronized AsynchronousCommandExecutor getInstance() throws AsynchronousCommandException {
if (singleton == null) {
try {
singleton = new AsynchronousCommandExecutor();
} catch (CacheException e) {
throw new AsynchronousCommandException("Cannot create CacheManager. Detailed message is: "
+ e.getMessage(), e);
}
}
return singleton;
}
/**
* Must be synchronized as potentially two threads could create new queues at the same time, with the result
* that one element would be lost.
*
* @return the queue of messages, or if none existed, a new queue
* @throws AsynchronousCommandException
*/
synchronized Queue getQueue() throws AsynchronousCommandException {
Queue queue;
Ehcache cache = getMessageCache();
Element element;
try {
element = cache.get(QUEUE_KEY);
} catch (CacheException e) {
throw new AsynchronousCommandException("Unable to retrieve queue.", e);
}
if (element == null) {
queue = new ConcurrentLinkedQueue();
Element queueElement = new Element(QUEUE_KEY, queue);
cache.put(queueElement);
} else {
queue = (Queue) element.getValue();
}
return queue;
}
/**
* Gets the message cache
*
* @return the {@link #MESSAGE_CACHE} cache
* @throws AsynchronousCommandException if the {@link #MESSAGE_CACHE} is null
*/
public Ehcache getMessageCache() throws AsynchronousCommandException {
Ehcache cache = cacheManager.getEhcache(MESSAGE_CACHE);
if (cache == null) {
throw new AsynchronousCommandException(
"ehcache.xml with a configuration entry for " +
MESSAGE_CACHE + " was not found in the classpath.");
}
return cache;
}
/**
* Stores parameters in the {@link #MESSAGE_CACHE} for later execution. A unique id is assigned to the
* PublisherCommand and that id is enqueued. Values stored will persist across VM restarts, provided the
* VM shutdown hooks have a chance to run.
* <p/>
* This method is synchronized because the underlying Queue implementation is not threadsafe.
*
* @param command the {@link Command} which will be called on to publish the message
* @return the unique identifier for the command
* @throws AsynchronousCommandException
*/
public synchronized String queueForExecution(Command command) throws AsynchronousCommandException {
InstrumentedCommand instrumentedCommand = new InstrumentedCommand(command);
String uid = storeCommandToCache(instrumentedCommand);
enqueue(uid);
notifyAll();
return uid;
}
private void enqueue(String uid) throws AsynchronousCommandException {
Queue queue;
queue = getQueue();
queue.add(uid);
}
/**
* Gets the number of attempts for the command so far
*
* @param uid - the unique id for the command returned from {@link #queueForExecution(Command)}
* @return the number of times the command was executed
* @throws CommandNotFoundInCacheException
* if the command was not found in the cache.
* @throws AsynchronousCommandException if their is a problem accessing the cache.
*/
public synchronized int getExecuteAttemptsForCommand(String uid) throws CommandNotFoundInCacheException,
AsynchronousCommandException {
InstrumentedCommand instrumentedCommand = retrieveInstrumentedCommandFromCache(uid);
if (instrumentedCommand == null) {
throw new CommandNotFoundInCacheException("Command " + uid + " + was not found in the messageCache");
}
return instrumentedCommand.getExecuteAttempts();
}
/**
* A background thread that executes commands
*/
private class DispatcherThread extends Thread {
public DispatcherThread() {
super("Message Dispatcher Thread");
//allow VM to exit with this thread running
setDaemon(true);
}
/**
* RemoteDebugger thread method.
*/
public void run() {
dispatcherThreadMain();
}
}
/**
* The main method for the expiry thread.
* <p/>
* Will run while the cache is active. After the cache shuts down
* it will take the expiryThreadInterval to wake up and complete.
* <p/>
* Any exceptions are logged.
*/
private synchronized void dispatcherThreadMain() {
while (true) {
try {
//wait for new messages or retry interval.
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("dispatcherThreadIntervalSeconds: " + dispatcherThreadIntervalSeconds);
}
wait(dispatcherThreadIntervalSeconds * MS_PER_SECOND);
} catch (InterruptedException e) {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("messageCache: Dispatcher thread interrupted on Disk Store.");
}
//Should only happen on dispose.
return;
}
if (!active) {
return;
}
executeCommands();
}
}
/**
* Dequeues messages and sends thems until a failure occurs, in which case, we wait until next time
* to try again.
* <p/>
* Each message in the queue is tried. There are many many reasons why a message can fail. It may be unique to the message
* such as a MessageFormatException, a non-serializable message and so on, in which case it may only affect that
* message. Or it could be that the service is down. Attempts are made to itentify messages that can never be
* delivered so that they can be deleted and hold up the queue. No messages can be sent out of order, or the queue
* rules will be broken. Subscribers may also be reliant on getting the messages in the right order. e.g. a delete
* or update can only happen after an insert for a given domain object.
* <p/>
* This method is synchronized so that it will always complete before a dispose occurs.
*/
private synchronized void executeCommands() {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("executeCommands invoked. " + countCachedPublishCommands() + " messages to be sent.");
}
Queue queue = null;
InstrumentedCommand instrumentedCommand = null;
try {
queue = getQueue();
} catch (AsynchronousCommandException e) {
LOG.log(Level.SEVERE, "Unable to access the cache to retrieve commands. ", e);
}
Object object = null;
while (true) {
object = queue.peek();
if (object == null) {
break;
}
String uid = (String) object;
try {
try {
instrumentedCommand = retrieveInstrumentedCommandFromCache(uid);
instrumentedCommand.attemptExecution();
remove(queue, uid, SUCCESSFUL_EXECUTION);
} catch (RetryAttemptTooSoonException e) {
if (LOG.isLoggable(Level.FINE)) {
LOG.log(Level.FINE, e.getMessage(), e);
}
break;
} catch (TooManyRetriesException e) {
remove(queue, uid, e.getMessage());
} catch (CommandNotFoundInCacheException e) {
remove(queue, uid, e.getMessage());
}
} catch (Throwable throwable) {
boolean match = checkIfRetryOnThrowable(throwable, instrumentedCommand);
if (!match) {
remove(queue, uid, throwable.getMessage());
} else {
//retry
if (LOG.isLoggable(Level.INFO)) {
LOG.log(Level.INFO, "Publishing attempt number " + instrumentedCommand.getExecuteAttempts()
+ " failed. " + throwable.getMessage(), throwable);
}
break;
}
}
}
}
private boolean checkIfRetryOnThrowable(Throwable throwable, InstrumentedCommand instrumentedCommand) {
Command command = instrumentedCommand.command;
Class[] retryThrowables = command.getThrowablesToRetryOn();
if (retryThrowables == null) {
return false;
}
boolean match = false;
for (int i = 0; i < retryThrowables.length; i++) {
Class retryThrowable = retryThrowables[i];
if (retryThrowable.isInstance(throwable)) {
match = true;
}
}
return match;
}
private void remove(Queue queue, String uid, String reason) {
queue.remove();
Ehcache cache = null;
try {
cache = getMessageCache();
} catch (AsynchronousCommandException e) {
LOG.log(Level.SEVERE, "Unable to get cache + " + e.getMessage(), e);
}
cache.remove(uid);
if (reason.equals(SUCCESSFUL_EXECUTION)) {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Deleting command with uid " + uid + ". " + reason);
}
} else {
LOG.severe("Deleting command with uid " + uid + ". " + reason);
}
}
private InstrumentedCommand retrieveInstrumentedCommandFromCache(String uid)
throws CommandNotFoundInCacheException {
Element element = null;
try {
//Cache not alive here. Why?
Ehcache cache = getMessageCache();
element = cache.get(uid);
} catch (Exception e) {
throw new CommandNotFoundInCacheException("Cache error while retrieving command", e);
}
if (element == null) {
throw new CommandNotFoundInCacheException("Command " + uid + " not found in cache.");
}
return (InstrumentedCommand) element.getValue();
}
/**
* Some caches might be persistent, so we want to add a shutdown hook if that is the
* case, so that the data and index can be written to disk.
*/
private void addShutdownHook() {
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
synchronized (this) {
if (active) {
LOG.info("VM shutting down with the MessageDispatcher active. There are "
+ countCachedPublishCommands() +
" messages which will be cached to disk for delivery on VM restart.");
dispose();
}
}
}
});
}
/**
* @return the approximate number of PublishCommands stored in the cache
*/
public synchronized int countCachedPublishCommands() {
int messageCount = 0;
try {
Ehcache cache = getMessageCache();
messageCount = cache.getSize();
} catch (Exception e) {
LOG.log(Level.SEVERE, "Unable to determine the number"
+ " of messages in the messageCache.", e);
}
if (messageCount != 0) {
//don't count queue, which should always be there.
messageCount--;
}
return messageCount;
}
/**
* ehcache also has a shutdown hook, so it will save all to disk.
* <p/>
* Shuts down the disk store in preparation for cache shutdown
* <p/>
* If a VM crash happens, the shutdown hook will not run. The data file and the index file
* will be out of synchronisation. At initialisation we always delete the index file
* after we have read the elements, so that it has a zero length. On a dirty restart, it still will have
* and the data file will automatically be deleted, thus preserving safety.
*/
public synchronized void dispose() {
int messages = countCachedPublishCommands();
LOG.info("Shutting down Message Dispatcher. " + messages + " messages remaining.");
if (!active) {
return;
}
try {
if (dispatcherThread != null) {
dispatcherThread.interrupt();
}
} catch (Exception e) {
LOG.log(Level.SEVERE, "Could not shut down MessageDispatcher", e);
} finally {
active = false;
notifyAll();
}
}
/**
* @param instrumentedCommand
* @return A unique id which acts as a handle to the message
* @throws AsynchronousCommandException
*/
String storeCommandToCache(InstrumentedCommand instrumentedCommand) throws AsynchronousCommandException {
String uid = generateUniqueIdentifier();
Element element = new Element(uid, instrumentedCommand);
Ehcache messageCache = getMessageCache();
messageCache.put(element);
return uid;
}
/**
* Generates an ID that is guaranteed to be unique for all VM invocations on a machine with a
* given IP address.
*
* @return A String representation of the unique identifier.
*/
String generateUniqueIdentifier() {
VMID guid = new VMID();
return guid.toString();
}
/**
* Sets the interval between runs of the dispatch thread, when no new dispatch invocations have occurred.
*
* @param dispatcherThreadIntervalSeconds
* the time in seconds
* @throws IllegalArgumentException if the argument is less than 30
* @see #DEFAULT_DISPATCHER_THREAD_INTERVAL_SECONDS for more information.
*/
public void setDispatcherThreadIntervalSeconds(long dispatcherThreadIntervalSeconds)
throws IllegalArgumentException {
if (dispatcherThreadIntervalSeconds < MINIMUM_SAFE_DISPATCHER_THREAD_INTERVAL) {
throw new IllegalArgumentException("Must be greater than 30 seconds to avoid high cpu load");
}
setUnsafeDispatcherThreadIntervalSeconds(dispatcherThreadIntervalSeconds);
}
/**
* Sets the interval between runs of the dispatch thread, when no new dispatch invocations have occurred.
* <p/>
* Provided with package local access to permit testing
*
* @param dispatcherThreadIntervalSeconds
* the time in seconds
* @see #DEFAULT_DISPATCHER_THREAD_INTERVAL_SECONDS for more information.
*/
public void setUnsafeDispatcherThreadIntervalSeconds(long dispatcherThreadIntervalSeconds) {
this.dispatcherThreadIntervalSeconds = dispatcherThreadIntervalSeconds;
}
/**
* A <code>Command</code> instrumented with information about retry attempts
*/
private final static class InstrumentedCommand implements Serializable {
private Command command;
/**
* A record of the attempts to execute this command
*/
private Stack executeAttempts;
private InstrumentedCommand(Command command) {
this.command = command;
executeAttempts = new Stack();
}
/**
* Records the data and time an execution attempt was made
*/
private void registerExecutionAttempt() {
Date date = new Date();
executeAttempts.add(date);
}
private void attemptExecution() throws Throwable, TooManyRetriesException, RetryAttemptTooSoonException {
checkAttemptNotTooSoon();
checkNotTooManyAttempts();
command.execute();
}
/**
* Checks that enough time has elapsed to attempt an execution
*
* @throws RetryAttemptTooSoonException if sufficient time has not elapsed
*/
private void checkAttemptNotTooSoon() throws RetryAttemptTooSoonException {
//must guard against this because of the design of stack
if (!executeAttempts.empty()) {
Date lastAttempt = (Date) executeAttempts.peek();
long delay = command.getDelayBetweenAttemptsInSeconds() * MS_PER_SECOND;
Date nextAttemptDue = new Date(lastAttempt.getTime() + (delay));
Date now = new Date();
if (now.before(nextAttemptDue)) {
throw new RetryAttemptTooSoonException("Attempt to execute command before it is due is being ignored.");
}
}
}
/**
* Checks that the number of attempts does not exceed the number of attempts defined in the command
*
* @throws TooManyRetriesException
*/
private void checkNotTooManyAttempts() throws TooManyRetriesException {
registerExecutionAttempt();
if (getExecuteAttempts() > command.getNumberOfAttempts()) {
throw new TooManyRetriesException("Retry attempt number " + getExecuteAttempts() + " is greater than "
+ " the number permitted of " + command.getNumberOfAttempts()
+ ".\n" + this);
}
}
private int getExecuteAttempts() {
//must guard against this because of the design of stack
if (executeAttempts.empty()) {
return 0;
} else {
return executeAttempts.size();
}
}
/**
* @return a string representation of the object.
*/
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.append("InstrumentedCommand: \n")
.append(super.toString())
.append("Previous Execution Attempts: \n");
if (getExecuteAttempts() > 0) {
for (int i = 0; i < getExecuteAttempts(); i++) {
Date date = (Date) executeAttempts.get(i);
buffer.append(date).append(" ");
}
}
buffer.append("Command: \n") .append(command);
return buffer.toString();
}
}
}
The table below shows all metrics for AsynchronousCommandExecutor.java.
| Metric | Value | Description | |
|---|---|---|---|
| BLOCKS | 90.00 | Number of blocks | |
| BLOCK_COMMENT | 0.00 | Number of block comment lines | |
| COMMENTS | 195.00 | Comment lines | |
| COMMENT_DENSITY | 0.73 | Comment density | |
| COMPARISONS | 35.00 | Number of comparison operators | |
| CYCLOMATIC | 73.00 | Cyclomatic complexity | |
| DECL_COMMENTS | 30.00 | Comments in declarations | |
| DOC_COMMENT | 185.00 | Number of javadoc comment lines | |
| ELOC | 268.00 | Effective lines of code | |
| EXEC_COMMENTS | 9.00 | Comments in executable code | |
| EXITS | 62.00 | Procedure exits | |
| FUNCTIONS | 29.00 | Number of function declarations | |
| HALSTEAD_DIFFICULTY | 65.79 | Halstead difficulty | |
| HALSTEAD_EFFORT | 0.00 | Halstead effort | |
| INTERFACE_COMPLEXITY | 74.00 | Interface complexity | |
| JAVA0001 | 0.00 | JAVA0001 Package name does not contain only lower case letters | |
| JAVA0002 | 0.00 | JAVA0002 Package name does not begin with a top level domain name or country code | |
| JAVA0003 | 0.00 | JAVA0003 Minimize use of on-demand (.*) imports | |
| JAVA0004 | 0.00 | JAVA0004 Unnecessary import from java.lang | |
| JAVA0005 | 1.00 | JAVA0005 Imports not in specified order | |
| JAVA0006 | 0.00 | JAVA0006 Empty finally block | |
| JAVA0007 | 0.00 | JAVA0007 Should not declare public field | |
| JAVA0008 | 0.00 | JAVA0008 Empty catch block | |
| JAVA0009 | 0.00 | JAVA0009 Protected member in final class | |
| JAVA0010 | 0.00 | JAVA0010 Non-instantiable class does not contain a non-private static member | |
| JAVA0011 | 0.00 | JAVA0011 Abstract class does not contain an abstract method | |
| JAVA0012 | 0.00 | JAVA0012 Non-constructor method with same name as declaring class | |
| JAVA0013 | 0.00 | JAVA0013 Non-blank final field is not static | |
| JAVA0014 | 0.00 | JAVA0014 Class with only static members has non-private constructor | |
| JAVA0015 | 0.00 | JAVA0015 Package class contains public nested type | |
| JAVA0016 | 0.00 | JAVA0016 Abstract class contains public constructor | |
| JAVA0017 | 0.00 | JAVA0017 Class name does not have required form | |
| JAVA0018 | 0.00 | JAVA0018 Method name does not have required form | |
| JAVA0019 | 0.00 | JAVA0019 Interface name does not have required form | |
| JAVA0020 | 0.00 | JAVA0020 Field name does not have required form | |
| JAVA0021 | 0.00 | JAVA0021 Interface method name does not have required form | |
| JAVA0022 | 0.00 | JAVA0022 Static final field name does not have required form | |
| JAVA0023 | 0.00 | JAVA0023 Empty finalize method | |
| JAVA0024 | 0.00 | JAVA0024 Empty class | |
| JAVA0025 | 0.00 | JAVA0025 Method override is empty | |
| JAVA0026 | 0.00 | JAVA0026 Finalize method with parameters | |
| JAVA0029 | 0.00 | JAVA0029 Private method not used | |
| JAVA0030 | 0.00 | JAVA0030 Private field not used | |
| JAVA0031 | 0.00 | JAVA0031 Case statement not properly closed | |
| JAVA0032 | 0.00 | JAVA0032 Switch statement missing default | |
| JAVA0033 | 0.00 | JAVA0033 default: not last case in switch statement | |
| JAVA0034 | 0.00 | JAVA0034 Missing braces in if statement | |
| JAVA0035 | 0.00 | JAVA0035 Missing braces in for statement | |
| JAVA0036 | 0.00 | JAVA0036 Missing braces in while statement | |
| JAVA0038 | 0.00 | JAVA0038 Non-case label in switch statement | |
| JAVA0039 | 0.00 | JAVA0039 Break statement with label | |
| JAVA0040 | 0.00 | JAVA0040 Switch statement contains N cases (maximum: M) | |
| JAVA0041 | 0.00 | JAVA0041 Nested synchronized block | |
| JAVA0042 | 0.00 | JAVA0042 Empty synchronized statement | |
| JAVA0043 | 0.00 | JAVA0043 Inner class does not use outer class | |
| JAVA0044 | 0.00 | JAVA0044 Serializable class with no instance variables | |
| JAVA0045 | 0.00 | JAVA0045 Serializable class with only transient fields | |
| JAVA0046 | 0.00 | JAVA0046 Name of class not derived from Exception ends with 'Exception' | |
| JAVA0047 | 0.00 | JAVA0047 Serializable class derives from invalid base class | |
| JAVA0048 | 0.00 | JAVA0048 Name of class derived from Exception does not end with 'Exception' | |
| JAVA0049 | 0.00 | JAVA0049 Nested block at depth N (maximum: M) | |
| JAVA0050 | 0.00 | JAVA0050 Class derives from java.lang.Error | |
| JAVA0051 | 0.00 | JAVA0051 Class derives from java.lang.RuntimeException | |
| JAVA0052 | 0.00 | JAVA0052 Class derives from java.lang.Throwable | |
| JAVA0053 | 0.00 | JAVA0053 Unused label | |
| JAVA0054 | 0.00 | JAVA0054 Inheritance depth N exceeds maximum M | |
| JAVA0055 | 0.00 | JAVA0055 Class should be interface | |
| JAVA0056 | 0.00 | JAVA0056 Unnecessary abstract modifier for interface or annotation | |
| JAVA0057 | 0.00 | JAVA0057 Unnecessary default constructor | |
| JAVA0058 | 0.00 | JAVA0058 Constructor calls super() | |
| JAVA0059 | 0.00 | JAVA0059 Method override only calls super() | |
| JAVA0061 | 0.00 | JAVA0061 Inaccessible member in anonymous class | |
| JAVA0062 | 0.00 | JAVA0062 Public class missing public member or protected constructor | |
| JAVA0063 | 0.00 | JAVA0063 Identifier name should not contain '$' | |
| JAVA0064 | 0.00 | JAVA0064 N variations of identifier name (maximum: M) | |
| JAVA0065 | 0.00 | JAVA0065 Unnecessary final modifier for method in final class | |
| JAVA0066 | 0.00 | JAVA0066 Unnecessary modifier for interface nested type | |
| JAVA0067 | 0.00 | JAVA0067 Array descriptor on identifier name | |
| JAVA0068 | 1.00 | JAVA0068 Modifiers not declared in recommended order | |
| JAVA0071 | 0.00 | JAVA0071 Strings compared with == | |
| JAVA0073 | 0.00 | JAVA0073 Integer division in floating-point context | |
| JAVA0074 | 0.00 | JAVA0074 Use of Object.notify() | |
| JAVA0075 | 0.00 | JAVA0075 Method parameter hides field | |
| JAVA0076 | 0.00 | JAVA0076 Use of magic number | |
| JAVA0077 | 0.00 | JAVA0077 Private field not used in declaring class | |
| JAVA0078 | 0.00 | JAVA0078 Floating point values compared with == | |
| JAVA0079 | 0.00 | JAVA0079 Use of instance to reference static member | |
| JAVA0080 | 0.00 | JAVA0080 Import declaration not used | |
| JAVA0081 | 0.00 | JAVA0081 Boolean literal in comparison | |
| JAVA0082 | 0.00 | JAVA0082 Unnecessary widening cast | |
| JAVA0083 | 0.00 | JAVA0083 Unnecessary instanceof test | |
| JAVA0084 | 0.00 | JAVA0084 Should use compound assignment operator | |
| JAVA0085 | 0.00 | JAVA0085 Use of sun.* class | |
| JAVA0087 | 1.00 | JAVA0087 Use of Thread.sleep() | |
| JAVA0089 | 0.00 | JAVA0089 Use of restricted package | |
| JAVA0092 | 0.00 | JAVA0092 Use of restricted type | |
| JAVA0093 | 0.00 | JAVA0093 Redundant assignment | |
| JAVA0094 | 0.00 | JAVA0094 Field hides a superclass field | |
| JAVA0095 | 0.00 | JAVA0095 Uninitialized private field | |
| JAVA0096 | 0.00 | JAVA0096 Field in nested class hides outer field | |
| JAVA0098 | 0.00 | JAVA0098 Minimize use of implicit field initializers | |
| JAVA0100 | 0.00 | JAVA0100 Class contains N non-final fields (maximum: M) | |
| JAVA0101 | 0.00 | JAVA0101 Unnecessary modifier for field in interface | |
| JAVA0102 | 0.00 | JAVA0102 Last statement in finalize() not super.finalize() | |
| JAVA0103 | 0.00 | JAVA0103 Explicit call to finalize() | |
| JAVA0104 | 0.00 | JAVA0104 finalize() only calls super.finalize() | |
| JAVA0105 | 0.00 | JAVA0105 Duplicate import declaration | |
| JAVA0106 | 0.00 | JAVA0106 Unnecessary import from current package | |
| JAVA0108 | 0.00 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| JAVA0109 | 0.00 | JAVA0109 Incorrect javadoc: no parameter 'parameter' | |
| JAVA0110 | 0.00 | JAVA0110 Incorrect javadoc: no @return tag | |
| JAVA0111 | 0.00 | JAVA0111 Incorrect javadoc: @return tag for void method | |
| JAVA0112 | 0.00 | JAVA0112 Incorrect javadoc: no exception 'exception' in throws | |
| JAVA0113 | 0.00 | JAVA0113 Incorrect javadoc: no @author tag | |
| JAVA0114 | 0.00 | JAVA0114 Incorrect javadoc: no @version tag | |
| JAVA0115 | 0.00 | JAVA0115 Incorrect javadoc: no @throws or @exception tag for 'exception' | |
| JAVA0116 | 0.00 | JAVA0116 Missing javadoc: field 'field' | |
| JAVA0117 | 1.00 | JAVA0117 Missing javadoc: method 'method' | |
| JAVA0118 | 0.00 | JAVA0118 Missing javadoc: type 'type' | |
| JAVA0119 | 0.00 | JAVA0119 Control variable changed within body of for loop | |
| JAVA0123 | 0.00 | JAVA0123 Use all three components of for loop | |
| JAVA0125 | 0.00 | JAVA0125 Continue statement with label | |
| JAVA0126 | 2.00 | JAVA0126 Method declares unchecked exception in throws | |
| JAVA0128 | 1.00 | JAVA0128 Public constructor in non-public class | |
| JAVA0130 | 2.00 | JAVA0130 Non-static method does not use instance fields | |
| JAVA0131 | 0.00 | JAVA0131 Compatible method does not override base | |
| JAVA0132 | 0.00 | JAVA0132 Method overload with compatible signature | |
| JAVA0133 | 0.00 | JAVA0133 Non-synchronized method overrides synchronized method | |
| JAVA0135 | 0.00 | JAVA0135 Only one of Object.equals and Object.hashCode defined: missing 'method' | |
| JAVA0136 | 0.00 | JAVA0136 N methods defined in class (maximum: M) | |
| JAVA0137 | 0.00 | JAVA0137 Non-abstract class missing constructor | |
| JAVA0138 | 0.00 | JAVA0138 N parameters defined for method (maximum: M) | |
| JAVA0139 | 0.00 | JAVA0139 Definition of main other than public static void main(java.lang.String[]) | |
| JAVA0141 | 0.00 | JAVA0141 Unnecessary modifier for method in interface | |
| JAVA0143 | 8.00 | JAVA0143 Synchronized method | |
| JAVA0144 | 0.00 | JAVA0144 Line exceeds maximum M characters | |
| JAVA0145 | 0.00 | JAVA0145 Tab character used in source file | |
| JAVA0150 | 0.00 | JAVA0150 java.lang.Error (or subclass) thrown | |
| JAVA0153 | 0.00 | JAVA0153 Inefficient conversion of integer to string | |
| JAVA0159 | 0.00 | JAVA0159 Inefficient conversion of string to integer | |
| JAVA0160 | 0.00 | JAVA0160 Method does not throw specified exception | |
| JAVA0161 | 0.00 | JAVA0161 Conditional wait() not in loop | |
| JAVA0163 | 0.00 | JAVA0163 Empty statement | |
| JAVA0165 | 0.00 | JAVA0165 Conflicting return statement in finally block | |
| JAVA0166 | 4.00 | JAVA0166 Generic exception caught | |
| JAVA0167 | 0.00 | JAVA0167 ThreadDeath not rethrown | |
| JAVA0169 | 0.00 | JAVA0169 Unnecessary catch block: exception 'exception' | |
| JAVA0170 | 1.00 | JAVA0170 Caught exception not derived from java.lang.Exception | |
| JAVA0171 | 0.00 | JAVA0171 Unused local variable | |
| JAVA0173 | 0.00 | JAVA0173 Unused method parameter | |
| JAVA0174 | 0.00 | JAVA0174 Assigned local variable never used | |
| JAVA0175 | 0.00 | JAVA0175 Successive assignment to variable | |
| JAVA0176 | 0.00 | JAVA0176 Local variable name does not have required form | |
| JAVA0177 | 3.00 | JAVA0177 Variable declaration missing initializer | |
| JAVA0179 | 0.00 | JAVA0179 Local variable hides visible field | |
| JAVA0233 | 0.00 | JAVA0233 Definition of serialVersionUID other than 'private static final long serialVersionUID' | |
| JAVA0234 | 1.00 | JAVA0234 Class is Serializable but does not define serialVersionUID | |
| JAVA0235 | 0.00 | JAVA0235 Class defines serialVersionUID but does not implement Serializable | |
| JAVA0236 | 0.00 | JAVA0236 Attempt to clone an object which does not implement Cloneable | |
| JAVA0237 | 0.00 | JAVA0237 Class implements Cloneable but does not have public clone method | |
| JAVA0238 | 0.00 | JAVA0238 Clone method does not call super.clone() | |
| JAVA0239 | 0.00 | JAVA0239 Class declares 'readObject' or 'writeObject' but does not implement Serializable | |
| JAVA0240 | 0.00 | JAVA0240 Serializable class which declares readObject or writeObject but not both | |
| JAVA0241 | 0.00 | JAVA0241 'readObject' or 'writeObject' should be declared private in Serializable class | |
| JAVA0242 | 0.00 | JAVA0242 Transient field in non-Serializable class | |
| JAVA0243 | 0.00 | JAVA0243 'readResolve' or 'writeReplace' should be declared private or protected | |
| JAVA0244 | 0.00 | JAVA0244 Field or method name in subclass differs only by case from inherited field or method | |
| JAVA0245 | 0.00 | JAVA0245 JUnit TestCase with non-trivial constructor | |
| JAVA0246 | 0.00 | JAVA0246 JUnit assertXXX statement missing message parameter | |
| JAVA0247 | 0.00 | JAVA0247 JUnit 'setUp()' and 'tearDown()' should call super method | |
| JAVA0248 | 0.00 | JAVA0248 JUnit method 'setUp' or 'tearDown' with incorrect signature | |
| JAVA0249 | 0.00 | JAVA0249 JUnit TestCase 'suite()' should be declared static | |
| JAVA0250 | 0.00 | JAVA0250 JUnit TestCase declares testXXX method with incorrect signature | |
| JAVA0251 | 0.00 | JAVA0251 Use '%n' for line breaks in printf/format for platform independence | |
| JAVA0252 | 0.00 | JAVA0252 'enum' is a Java 1.5 reserved word | |
| JAVA0253 | 0.00 | JAVA0253 Not all enum constants consumed in switch statement | |
| JAVA0254 | 0.00 | JAVA0254 Use enhanced for loop construct instead of Iterator | |
| JAVA0255 | 0.00 | JAVA0255 Result of method invocation not used | |
| JAVA0256 | 0.00 | JAVA0256 Assignment of external collection/array to field | |
| JAVA0257 | 0.00 | JAVA0257 Use of 'Constant Interface' anti-pattern | |
| JAVA0258 | 0.00 | JAVA0258 Implement Iterable for foreach compatibility | |
| JAVA0259 | 0.00 | JAVA0259 Return of collection/array field | |
| JAVA0260 | 0.00 | JAVA0260 Use 'enum' instead of Enumerated Type pattern | |
| JAVA0261 | 0.00 | JAVA0261 Use specialized Enum collection types | |
| JAVA0262 | 0.00 | JAVA0262 Use of char in integer context | |
| JAVA0263 | 0.00 | JAVA0263 Long literal ends with 'l' instead of 'L' | |
| JAVA0264 | 1.00 | JAVA0264 Integer math in long context - check for overflow | |
| JAVA0265 | 0.00 | JAVA0265 Use of Throwable.printStackTrace() | |
| JAVA0266 | 0.00 | JAVA0266 Use of System.out | |
| JAVA0267 | 0.00 | JAVA0267 Use of System.err | |
| JAVA0269 | 0.00 | JAVA0269 Contents of StringBuffer never used | |
| JAVA0270 | 1.00 | JAVA0270 Use Java 5.0 enhanced for loop construct to iterate over all elements in an array | |
| JAVA0271 | 0.00 | JAVA0271 Minimize use of on-demand (.*) static imports | |
| JAVA0272 | 0.00 | JAVA0272 Thread.run() called | |
| JAVA0273 | 0.00 | JAVA0273 Non-final derivative of Thread calls start() in constructor | |
| JAVA0274 | 0.00 | JAVA0274 Serializable class has a synchronized readObject() | |
| JAVA0275 | 0.00 | JAVA0275 Serializable class has a synchronized writeObject() and no other synchronized methods | |
| JAVA0276 | 0.00 | JAVA0276 Unnecessary use of String constructor | |
| JAVA0277 | 0.00 | JAVA0277 Iterator.next() implementation does not throw NoSuchElementException | |
| JAVA0278 | 0.00 | JAVA0278 Unnecessary use of Boolean constructor | |
| JAVA0279 | 0.00 | JAVA0279 Serialization method readObject or readObjectNoData calls an overridable method | |
| JAVA0280 | 0.00 | JAVA0280 IllegalMonitorStateException caught | |
| JAVA0281 | 0.00 | JAVA0281 Iterator.next() not called in loop | |
| JAVA0282 | 0.00 | JAVA0282 Call to Iterator.next() in loop which does not test Iterator.hasNext() | |
| JAVA0283 | 0.00 | JAVA0283 Control variable not updated in loop body | |
| JAVA0284 | 0.00 | JAVA0284 Explicit garbage collection | |
| JAVA0285 | 3.00 | JAVA0285 Dereference of potentially null variable | |
| JAVA0286 | 0.00 | JAVA0286 Dereference of null variable | |
| JAVA0287 | 0.00 | JAVA0287 Unnecessary null check | |
| JAVA0288 | 0.00 | JAVA0288 Inconsistent null check | |
| LINES | 604.00 | Number of lines in the source file | |
| LINE_COMMENT | 10.00 | Number of line comments | |
| LOC | 343.00 | Lines of code | |
| LOGICAL_LINES | 164.00 | Number of statements | |
| LOOPS | 4.00 | Number of loops | |
| NEST_DEPTH | 5.00 | Maximum nesting depth | |
| OPERANDS | 650.00 | Number of operands | |
| OPERATORS | 1342.00 | Number of operators | |
| PARAMS | 13.00 | Number of formal parameter declarations | |
| PROGRAM_LENGTH | 1992.00 | Halstead program length | |
| PROGRAM_VOCAB | 297.00 | Halstead program vocabulary | |
| PROGRAM_VOLUME | 0.00 | Halstead program volume | |
| RETURNS | 61.00 | Number of return points from functions | |
| SIZE | 23025.00 | Size of the file in bytes | |
| UNIQUE_OPERANDS | 247.00 | Number of unique operands | |
| UNIQUE_OPERATORS | 50.00 | Number of unique operators | |
| WHITESPACE | 66.00 | Number of whitespace lines | |