DiskStore.java
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net.sf.ehcache.store |
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ehcache |
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|---|---|---|
| EXEC_COMMENTS | Comments in executable code |  |
| DECL_COMMENTS | Comments in declarations | |
| SIZE | Size of the file in bytes | |
| BLOCKS | Number of blocks | |
| EXITS | Procedure exits | |
| LINE_COMMENT | Number of line comments | |
| JAVA0143 | JAVA0143 Synchronized method | |
| DOC_COMMENT | Number of javadoc comment lines | |
| LINES | Number of lines in the source file | |
| RETURNS | Number of return points from functions | |
| LOGICAL_LINES | Number of statements | |
| JAVA0166 | JAVA0166 Generic exception caught | |
| CYCLOMATIC | Cyclomatic complexity | |
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| LOC | Lines of code | |
| OPERATORS | Number of operators | |
| COMMENTS | Comment lines | |
| PROGRAM_LENGTH | Halstead program length | |
| COMPARISONS | Number of comparison operators | |
| JAVA0177 | JAVA0177 Variable declaration missing initializer | |
| UNIQUE_OPERANDS | Number of unique operands | |
| OPERANDS | Number of operands | |
| FUNCTIONS | Number of function declarations | |
| PROGRAM_VOCAB | Halstead program vocabulary | |
| INTERFACE_COMPLEXITY | Interface complexity | |
| JAVA0110 | JAVA0110 Incorrect javadoc: no @return tag | |
| JAVA0115 | JAVA0115 Incorrect javadoc: no @throws or @exception tag for 'exception' | |
| JAVA0077 | JAVA0077 Private field not used in declaring class | |
| JAVA0034 | JAVA0034 Missing braces in if statement | |
| JAVA0144 | JAVA0144 Line exceeds maximum M characters | |
| WHITESPACE | Number of whitespace lines | |
| JAVA0170 | JAVA0170 Caught exception not derived from java.lang.Exception | |
| UNIQUE_OPERATORS | Number of unique operators | |
| JAVA0049 | JAVA0049 Nested block at depth N (maximum: M) | |
| LOOPS | Number of loops | |
| JAVA0282 | JAVA0282 Call to Iterator.next() in loop which does not test Iterator.hasNext() | |
| JAVA0128 | JAVA0128 Public constructor in non-public class | |
| NEST_DEPTH | Maximum nesting depth | |
| PROGRAM_VOLUME | Halstead program volume | |
| JAVA0136 | JAVA0136 N methods defined in class (maximum: M) | |
| JAVA0174 | JAVA0174 Assigned local variable never used | |
| JAVA0160 | JAVA0160 Method does not throw specified exception | |
| JAVA0273 | JAVA0273 Non-final derivative of Thread calls start() in constructor | |
| JAVA0264 | JAVA0264 Integer math in long context - check for overflow | |
| JAVA0087 | JAVA0087 Use of Thread.sleep() | |
| JAVA0117 | JAVA0117 Missing javadoc: method 'method' | |
| JAVA0100 | JAVA0100 Class contains N non-final fields (maximum: M) | |
| JAVA0130 | JAVA0130 Non-static method does not use instance fields | |
| JAVA0108 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| 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.store;
import net.sf.ehcache.CacheException;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.Status;
import net.sf.ehcache.util.MemoryEfficientByteArrayOutputStream;
import net.sf.ehcache.event.RegisteredEventListeners;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.RandomAccessFile;
import java.io.Serializable;
import java.io.StreamCorruptedException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Logger;
import java.util.logging.Level;
/**
* A disk store implementation.
* <p/>
* As of ehcache-1.2 (v1.41 of this file) DiskStore has been changed to a mix of finer grained locking using synchronized collections
* and synchronizing on the whole instance, as was the case with earlier versions.
* <p/>
* The DiskStore, as of ehcache-1.2.4, supports eviction using an LFU policy, if a maximum disk
* store size is set. LFU uses statistics held at the Element level which survive moving between
* maps in the MemoryStore and DiskStores.
*
* @author Adam Murdoch
* @author Greg Luck
* @author patches contributed: Ben Houston
* @version $Id: DiskStore.java 744 2008-08-16 20:10:49Z gregluck $
*/
public class DiskStore implements Store {
/**
* If the CacheManager needs to resolve a conflict with the disk path, it will create a
* subdirectory in the given disk path with this prefix followed by a number. The presence of this
* name is used to determined whether it makes sense for a persistent DiskStore to be loaded. Loading
* persistent DiskStores will only have useful semantics where the diskStore path has not changed.
*/
public static final String AUTO_DISK_PATH_DIRECTORY_PREFIX = "ehcache_auto_created";
private static final Logger LOG = Logger.getLogger(DiskStore.class.getName());
private static final int MS_PER_SECOND = 1000;
private static final int SPOOL_THREAD_INTERVAL = 200;
private static final int ESTIMATED_MINIMUM_PAYLOAD_SIZE = 512;
private static final int ONE_MEGABYTE = 1048576;
private long expiryThreadInterval;
private final String name;
private boolean active;
private RandomAccessFile randomAccessFile;
private Map diskElements = Collections.synchronizedMap(new HashMap());
private List freeSpace = Collections.synchronizedList(new ArrayList());
private Map spool = new HashMap();
private Object spoolLock = new Object();
private Thread spoolAndExpiryThread;
private Ehcache cache;
/**
* If persistent, the disk file will be kept
* and reused on next startup. In addition the
* memory store will flush all contents to spool,
* and spool will flush all to disk.
*/
private final boolean persistent;
private final String diskPath;
private File dataFile;
/**
* Used to persist elements
*/
private File indexFile;
private Status status;
/**
* The size in bytes of the disk elements
*/
private long totalSize;
/**
* The maximum elements to allow in the disk file.
*/
private final long maxElementsOnDisk;
/**
* Whether the cache is eternal
*/
private boolean eternal;
private int lastElementSize;
private int diskSpoolBufferSizeBytes;
/**
* Creates a disk store.
*
* @param cache the {@link net.sf.ehcache.Cache} that the store is part of
* @param diskPath the directory in which to create data and index files
*/
public DiskStore(Ehcache cache, String diskPath) {
status = Status.STATUS_UNINITIALISED;
this.cache = cache;
name = cache.getName();
this.diskPath = diskPath;
expiryThreadInterval = cache.getDiskExpiryThreadIntervalSeconds();
persistent = cache.isDiskPersistent();
maxElementsOnDisk = cache.getMaxElementsOnDisk();
eternal = cache.isEternal();
diskSpoolBufferSizeBytes = cache.getCacheConfiguration().getDiskSpoolBufferSizeMB() * ONE_MEGABYTE;
try {
initialiseFiles();
active = true;
// Always start up the spool thread
spoolAndExpiryThread = new SpoolAndExpiryThread();
spoolAndExpiryThread.start();
status = Status.STATUS_ALIVE;
} catch (final Exception e) {
// Cleanup on error
dispose();
throw new CacheException(name + "Cache: Could not create disk store. " +
"Initial cause was " + e.getMessage(), e);
}
}
private void initialiseFiles() throws Exception {
// Make sure the cache directory exists
final File diskDir = new File(diskPath);
if (diskDir.exists() && !diskDir.isDirectory()) {
throw new Exception("Store directory \"" + diskDir.getCanonicalPath() + "\" exists and is not a directory.");
}
if (!diskDir.exists() && !diskDir.mkdirs()) {
throw new Exception("Could not create cache directory \"" + diskDir.getCanonicalPath() + "\".");
}
dataFile = new File(diskDir, getDataFileName());
indexFile = new File(diskDir, getIndexFileName());
deleteIndexIfNoData();
if (persistent) {
//if diskpath contains auto generated string
if (diskPath.indexOf(AUTO_DISK_PATH_DIRECTORY_PREFIX) != -1) {
LOG.warning("Data in persistent disk stores is ignored for stores from automatically created directories"
+ " (they start with " + AUTO_DISK_PATH_DIRECTORY_PREFIX + ").\n"
+ "Remove diskPersistent or resolve the conflicting disk paths in cache configuration.\n"
+ "Deleting data file " + getDataFileName());
dataFile.delete();
} else if (!readIndex()) {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Index file dirty or empty. Deleting data file " + getDataFileName());
}
dataFile.delete();
}
} else {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Deleting data file " + getDataFileName());
}
dataFile.delete();
indexFile = null;
}
// Open the data file as random access. The dataFile is created if necessary.
randomAccessFile = new RandomAccessFile(dataFile, "rw");
}
private void deleteIndexIfNoData() {
boolean dataFileExists = dataFile.exists();
boolean indexFileExists = indexFile.exists();
if (!dataFileExists && indexFileExists) {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Matching data file missing for index file. Deleting index file " + getIndexFileName());
}
indexFile.delete();
}
}
/**
* Asserts that the store is active.
*/
private void checkActive() throws CacheException {
if (!active) {
throw new CacheException(name + " Cache: The Disk store is not active.");
}
}
/**
* Gets an {@link Element} from the Disk Store.
*
* @return The element
*/
public final synchronized Element get(final Object key) {
try {
checkActive();
// Check in the spool. Remove if present
Element element;
synchronized (spoolLock) {
element = (Element) spool.remove(key);
}
if (element != null) {
element.updateAccessStatistics();
return element;
}
// Check if the element is on disk
final DiskElement diskElement = (DiskElement) diskElements.get(key);
if (diskElement == null) {
// Not on disk
return null;
}
element = loadElementFromDiskElement(diskElement);
element.updateAccessStatistics();
return element;
} catch (Exception exception) {
LOG.log(Level.SEVERE, name + "Cache: Could not read disk store element for key " + key + ". Error was "
+ exception.getMessage(), exception);
}
return null;
}
/**
* An unsynchronized and very low cost check to see if a key is in the Store. No check is made to see if the Element is expired.
*
* @param key The Element key
* @return true if found. If this method return false, it means that an Element with the given key is definitely not in the MemoryStore.
* If it returns true, there is an Element there. An attempt to get it may return null if the Element has expired.
*/
public final boolean containsKey(Object key) {
return diskElements.containsKey(key) || spool.containsKey(key);
}
private Element loadElementFromDiskElement(DiskElement diskElement) throws IOException, ClassNotFoundException {
Element element;
// Load the element
randomAccessFile.seek(diskElement.position);
final byte[] buffer = new byte[diskElement.payloadSize];
randomAccessFile.readFully(buffer);
final ByteArrayInputStream instr = new ByteArrayInputStream(buffer);
final ObjectInputStream objstr = new ObjectInputStream(instr) {
/**
* Overridden because of:
* Bug 1324221 ehcache DiskStore has issues when used in Tomcat
*/
protected Class resolveClass(ObjectStreamClass clazz) throws ClassNotFoundException, IOException {
try {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
return Class.forName(clazz.getName(), false, classLoader);
} catch (ClassNotFoundException e) {
// Use the default as a fallback because of
// bug 1517565 - DiskStore loadElementFromDiskElement
return super.resolveClass(clazz);
}
}
};
element = (Element) objstr.readObject();
objstr.close();
return element;
}
/**
* Gets an {@link Element} from the Disk Store, without updating statistics
*
* @return The element
*/
public final synchronized Element getQuiet(final Object key) {
try {
checkActive();
// Check in the spool. Remove if present
Element element;
synchronized (spoolLock) {
element = (Element) spool.remove(key);
}
if (element != null) {
//element.updateAccessStatistics(); Don't update statistics
return element;
}
// Check if the element is on disk
final DiskElement diskElement = (DiskElement) diskElements.get(key);
if (diskElement == null) {
// Not on disk
return null;
}
element = loadElementFromDiskElement(diskElement);
//element.updateAccessStatistics(); Don't update statistics
return element;
} catch (Exception e) {
LOG.log(Level.SEVERE, name + "Cache: Could not read disk store element for key " + key
+ ". Initial cause was " + e.getMessage(), e);
}
return null;
}
/**
* Gets an Array of the keys for all elements in the disk store.
*
* @return An Object[] of {@link Serializable} keys
*/
public final synchronized Object[] getKeyArray() {
Set elementKeySet;
synchronized (diskElements) {
elementKeySet = diskElements.keySet();
}
Set spoolKeySet;
synchronized (spoolLock) {
spoolKeySet = spool.keySet();
}
Set allKeysSet = new HashSet(elementKeySet.size() + spoolKeySet.size());
allKeysSet.addAll(elementKeySet);
allKeysSet.addAll(spoolKeySet);
return allKeysSet.toArray();
}
/**
* Returns the current store size.
*
*/
public final synchronized int getSize() {
try {
checkActive();
int spoolSize;
synchronized (spoolLock) {
spoolSize = spool.size();
}
int diskSize;
synchronized (diskElements) {
diskSize = diskElements.size();
}
return spoolSize + diskSize;
} catch (Exception e) {
LOG.log(Level.SEVERE, name + "Cache: Could not determine size of disk store.. Initial cause was " + e.getMessage(), e);
return 0;
}
}
/**
* Returns the store status.
*/
public final Status getStatus() {
return status;
}
/**
* Puts an element into the disk store.
* <p/>
* This method is not synchronized. It is however threadsafe. It uses fine-grained
* synchronization on the spool.
*/
public final void put(final Element element) {
try {
checkActive();
// Spool the element
if (spoolAndExpiryThread.isAlive()) {
synchronized (spoolLock) {
spool.put(element.getObjectKey(), element);
}
} else {
LOG.severe(name + "Cache: Elements cannot be written to disk store because the" +
" spool thread has died.");
synchronized (spoolLock) {
spool.clear();
}
}
} catch (Exception e) {
LOG.log(Level.SEVERE, name + "Cache: Could not write disk store element for " + element.getObjectKey()
+ ". Initial cause was " + e.getMessage(), e);
}
}
/**
* In some circumstances data can be written so quickly to the spool that the VM runs out of memory
* while waiting for the spooling to disk.
* <p/>
* This is a very simple and quick test which estimates the spool size based on the last element's written size.
*
* @return true if the spool is not being cleared fast enough
*/
public boolean backedUp() {
long estimatedSpoolSize = spool.size() * lastElementSize;
boolean backedUp = estimatedSpoolSize > diskSpoolBufferSizeBytes;
if (backedUp && LOG.isLoggable(Level.FINEST)) {
LOG.finest("A back up on cache puts occurred. Consider increasing diskSpoolBufferSizeMB for cache " + name);
}
return backedUp;
}
/**
* Removes an item from the disk store.
*
*/
public final synchronized Element remove(final Object key) {
Element element;
try {
checkActive();
// Remove the entry from the spool
synchronized (spoolLock) {
element = (Element) spool.remove(key);
}
// Remove the entry from the file. Could be in both places.
synchronized (diskElements) {
final DiskElement diskElement = (DiskElement) diskElements.remove(key);
if (diskElement != null) {
element = loadElementFromDiskElement(diskElement);
freeBlock(diskElement);
}
}
} catch (Exception exception) {
String message = name + "Cache: Could not remove disk store entry for key " + key
+ ". Error was " + exception.getMessage();
LOG.log(Level.SEVERE, message, exception);
throw new CacheException(message);
}
return element;
}
/**
* Marks a block as free.
*
* @param diskElement the DiskElement to move to the free space list
*/
private void freeBlock(final DiskElement diskElement) {
totalSize -= diskElement.payloadSize;
diskElement.payloadSize = 0;
//reset Element meta data
diskElement.key = null;
diskElement.hitcount = 0;
diskElement.expiryTime = 0;
freeSpace.add(diskElement);
}
/**
* Remove all of the elements from the store.
* <p/>
* If there are registered <code>CacheEventListener</code>s they are notified of the expiry or removal
* of the <code>Element</code> as each is removed.
*/
public final synchronized void removeAll() {
try {
checkActive();
// Ditch all the elements, and truncate the file
spool = Collections.synchronizedMap(new HashMap());
diskElements = Collections.synchronizedMap(new HashMap());
freeSpace = Collections.synchronizedList(new ArrayList());
totalSize = 0;
randomAccessFile.setLength(0);
if (persistent) {
indexFile.delete();
indexFile.createNewFile();
}
} catch (Exception e) {
// Clean up
LOG.log(Level.SEVERE, name + " Cache: Could not rebuild disk store. Initial cause was " + e.getMessage(), e);
dispose();
}
}
/**
* 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 final synchronized void dispose() {
if (!active) {
return;
}
// Close the cache
try {
flush();
//stop the spool thread
if (spoolAndExpiryThread != null) {
spoolAndExpiryThread.interrupt();
}
//Clear in-memory data structures
spool.clear();
diskElements.clear();
freeSpace.clear();
if (randomAccessFile != null) {
randomAccessFile.close();
}
if (!persistent) {
LOG.fine("Deleting file " + dataFile.getName());
dataFile.delete();
}
} catch (Exception e) {
LOG.log(Level.SEVERE, name + "Cache: Could not shut down disk cache. Initial cause was " + e.getMessage(), e);
} finally {
active = false;
randomAccessFile = null;
notifyAll();
//release reference to cache
cache = null;
}
}
/**
* Flush the spool if persistent, so we don't lose any data.
*
* @throws IOException
*/
public final void flush() throws IOException {
if (persistent) {
flushSpool();
writeIndex();
}
}
/**
* both flushing and expiring contend for the same lock on diskElement, so
* might as well do them sequentially in the one thread.
* <p/>
* This thread is protected from Throwables by only calling methods that guard
* against these.
*/
private void spoolAndExpiryThreadMain() {
long nextExpiryTime = System.currentTimeMillis();
while (true) {
try {
Thread.sleep(SPOOL_THREAD_INTERVAL);
} catch (InterruptedException e) {
LOG.fine("Spool Thread interrupted.");
return;
}
if (!active) {
return;
}
throwableSafeFlushSpoolIfRequired();
if (!active) {
return;
}
nextExpiryTime = throwableSafeExpireElementsIfRequired(nextExpiryTime);
}
}
private long throwableSafeExpireElementsIfRequired(long nextExpiryTime) {
long updatedNextExpiryTime = nextExpiryTime;
// Expire elements
if (!eternal && System.currentTimeMillis() > nextExpiryTime) {
try {
updatedNextExpiryTime += expiryThreadInterval * MS_PER_SECOND;
expireElements();
} catch (Throwable e) {
LOG.log(Level.SEVERE, name + " Cache: Could not expire elements from disk due to "
+ e.getMessage() + ". Continuing...", e);
}
}
return updatedNextExpiryTime;
}
private void throwableSafeFlushSpoolIfRequired() {
if (spool != null && spool.size() != 0) {
// Write elements to disk
try {
flushSpool();
} catch (Throwable e) {
LOG.log(Level.SEVERE, name + " Cache: Could not flush elements to disk due to " + e.getMessage() + ". Continuing...", e);
}
}
}
/**
* Flushes all spooled elements to disk.
* Note that the cache is locked for the entire time that the spool is being flushed.
*
*/
private synchronized void flushSpool() throws IOException {
if (spool.size() == 0) {
return;
}
Map copyOfSpool = swapSpoolReference();
//does not guarantee insertion order
Iterator valuesIterator = copyOfSpool.values().iterator();
while (valuesIterator.hasNext()) {
writeOrReplaceEntry(valuesIterator.next());
valuesIterator.remove();
}
}
private Map swapSpoolReference() {
Map copyOfSpool = null;
synchronized (spoolLock) {
// Copy the reference of the old spool, not the contents. Avoid potential spike in memory usage
copyOfSpool = spool;
// use a new map making the reference swap above SAFE
spool = Collections.synchronizedMap(new HashMap());
}
return copyOfSpool;
}
private void writeOrReplaceEntry(Object object) throws IOException {
Element element = (Element) object;
if (element == null) {
return;
}
final Serializable key = (Serializable) element.getObjectKey();
removeOldEntryIfAny(key);
if (maxElementsOnDisk > 0 && diskElements.size() >= maxElementsOnDisk) {
evictLfuDiskElement();
}
writeElement(element, key);
}
private void writeElement(Element element, Serializable key) throws IOException {
try {
int bufferLength;
long expirationTime = element.getExpirationTime();
try {
MemoryEfficientByteArrayOutputStream buffer =
MemoryEfficientByteArrayOutputStream.serialize(element, estimatedPayloadSize());
bufferLength = buffer.size();
DiskElement diskElement = checkForFreeBlock(bufferLength);
// Write the record
randomAccessFile.seek(diskElement.position);
randomAccessFile.write(buffer.toByteArray(), 0, bufferLength);
buffer = null;
// Add to index, update stats
diskElement.payloadSize = bufferLength;
diskElement.key = key;
diskElement.expiryTime = expirationTime;
diskElement.hitcount = element.getHitCount();
totalSize += bufferLength;
lastElementSize = bufferLength;
synchronized (diskElements) {
diskElements.put(key, diskElement);
}
} catch (OutOfMemoryError e) {
LOG.severe("OutOfMemoryError on serialize: " + key);
}
} catch (Exception e) {
// Catch any exception that occurs during serialization
LOG.log(Level.SEVERE, name + "Cache: Failed to write element to disk '" + key
+ "'. Initial cause was " + e.getMessage(), e);
}
}
private int estimatedPayloadSize() {
int size = 0;
try {
size = (int) (totalSize / diskElements.size());
} catch (Exception e) {
//
}
if (size <= 0) {
size = ESTIMATED_MINIMUM_PAYLOAD_SIZE;
}
return size;
}
/**
* Remove the old entry, if any
*
* @param key
*/
private void removeOldEntryIfAny(Serializable key) {
final DiskElement oldBlock;
synchronized (diskElements) {
oldBlock = (DiskElement) diskElements.remove(key);
}
if (oldBlock != null) {
freeBlock(oldBlock);
}
}
private DiskElement checkForFreeBlock(int bufferLength) throws IOException {
DiskElement diskElement = findFreeBlock(bufferLength);
if (diskElement == null) {
diskElement = new DiskElement();
diskElement.position = randomAccessFile.length();
diskElement.blockSize = bufferLength;
}
return diskElement;
}
/**
* Writes the Index to disk on shutdown
* <p/>
* The index consists of the elements Map and the freeSpace List
* <p/>
* Note that the cache is locked for the entire time that the index is being written
*/
private synchronized void writeIndex() throws IOException {
ObjectOutputStream objectOutputStream = null;
try {
FileOutputStream fout = new FileOutputStream(indexFile);
objectOutputStream = new ObjectOutputStream(fout);
objectOutputStream.writeObject(diskElements);
objectOutputStream.writeObject(freeSpace);
} finally {
if (objectOutputStream != null) {
objectOutputStream.close();
}
}
}
/**
* Reads Index to disk on startup.
* <p/>
* if the index file does not exist, it creates a new one.
* <p/>
* Note that the cache is locked for the entire time that the index is being written
*
* @return True if the index was read successfully, false otherwise
*/
private synchronized boolean readIndex() throws IOException {
ObjectInputStream objectInputStream = null;
FileInputStream fin = null;
boolean success = false;
if (indexFile.exists()) {
try {
fin = new FileInputStream(indexFile);
objectInputStream = new ObjectInputStream(fin);
diskElements = (Map) objectInputStream.readObject();
freeSpace = (List) objectInputStream.readObject();
success = true;
} catch (StreamCorruptedException e) {
LOG.severe("Corrupt index file. Creating new index.");
} catch (IOException e) {
//normal when creating the cache for the first time
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("IOException reading index. Creating new index. ");
}
} catch (ClassNotFoundException e) {
LOG.log(Level.SEVERE, "Class loading problem reading index. Creating new index. Initial cause was " + e.getMessage(), e);
} finally {
try {
if (objectInputStream != null) {
objectInputStream.close();
} else if (fin != null) {
fin.close();
}
} catch (IOException e) {
LOG.severe("Problem closing the index file.");
}
//Always zero out file. That way if there is a dirty shutdown, the file will still be empty
//the next time we start up and readIndex will automatically fail.
//If there was a problem reading the index this time we also want to zero it out.
createNewIndexFile();
}
} else {
createNewIndexFile();
}
//Return the success flag
return success;
}
private void createNewIndexFile() throws IOException {
if (indexFile.exists()) {
indexFile.delete();
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Index file " + indexFile + " deleted.");
}
}
if (indexFile.createNewFile()) {
if (LOG.isLoggable(Level.FINE)) {
LOG.fine("Index file " + indexFile + " created successfully");
}
} else {
throw new IOException("Index file " + indexFile + " could not created.");
}
}
/**
* Removes expired elements.
* <p/>
* Note that the DiskStore cannot efficiently expire based on TTI. It does it on TTL. However any gets out
* of the DiskStore are check for both before return.
*
*/
public void expireElements() {
final long now = System.currentTimeMillis();
// Clean up the spool
synchronized (spoolLock) {
for (Iterator iterator = spool.values().iterator(); iterator.hasNext();) {
final Element element = (Element) iterator.next();
if (element.isExpired()) {
// An expired element
if (LOG.isLoggable(Level.FINE)) {
LOG.fine(name + "Cache: Removing expired spool element " + element.getObjectKey());
}
iterator.remove();
notifyExpiryListeners(element);
}
}
}
Element element = null;
RegisteredEventListeners listeners = cache.getCacheEventNotificationService();
synchronized (diskElements) {
// Clean up disk elements
for (Iterator iterator = diskElements.entrySet().iterator(); iterator.hasNext();) {
final Map.Entry entry = (Map.Entry) iterator.next();
final DiskElement diskElement = (DiskElement) entry.getValue();
if (now >= diskElement.expiryTime) {
// An expired element
if (LOG.isLoggable(Level.FINE)) {
LOG.fine(name + "Cache: Removing expired spool element " + entry.getKey() + " from Disk Store");
}
iterator.remove();
// only load the element from the file if there is a listener interested in hearing about its expiration
if (listeners.hasCacheEventListeners()) {
try {
element = loadElementFromDiskElement(diskElement);
notifyExpiryListeners(element);
} catch (Exception exception) {
LOG.log(Level.SEVERE, name + "Cache: Could not remove disk store entry for " + entry.getKey()
+ ". Error was " + exception.getMessage(), exception);
}
}
freeBlock(diskElement);
}
}
}
}
/**
* It is enough that an element is expiring here. Notify even though there might be another
* element with the same key elsewhere in the stores.
*
* @param element
*/
private void notifyExpiryListeners(Element element) {
cache.getCacheEventNotificationService().notifyElementExpiry(element, false);
}
/**
* Allocates a free block.
*/
private DiskElement findFreeBlock(final int length) {
for (int i = 0; i < freeSpace.size(); i++) {
final DiskElement element = (DiskElement) freeSpace.get(i);
if (element.blockSize >= length) {
freeSpace.remove(i);
return element;
}
}
return null;
}
/**
* Returns a {@link String} representation of the {@link DiskStore}
*/
public final String toString() {
StringBuffer sb = new StringBuffer();
sb.append("[ dataFile = ").append(dataFile.getAbsolutePath())
.append(", active=").append(active)
.append(", totalSize=").append(totalSize)
.append(", status=").append(status)
.append(", expiryThreadInterval = ").append(expiryThreadInterval)
.append(" ]");
return sb.toString();
}
/**
* Generates a unique directory name for use in automatically creating a diskStorePath where there is a conflict.
*
* @return a path consisting of {@link #AUTO_DISK_PATH_DIRECTORY_PREFIX} followed by "_" followed by the current
* time as a long e.g. ehcache_auto_created_1149389837006
*/
public static String generateUniqueDirectory() {
return DiskStore.AUTO_DISK_PATH_DIRECTORY_PREFIX + "_" + System.currentTimeMillis();
}
/**
* A reference to an on-disk elements.
* <p/>
* Copies of expiryTime and hitcount are held here as a performance optimisation, so
* that we do not need to load the data from Disk to get this often used information.
*
*/
private static final class DiskElement implements Serializable, LfuPolicy.Metadata {
private static final long serialVersionUID = -717310932566592289L;
/**
* the file pointer
*/
private long position;
/**
* The size used for data.
*/
private int payloadSize;
/**
* the size of this element.
*/
private int blockSize;
/**
* The key this element is mapped with in DiskElements. This is only a reference
* to the key. It is used in DiskElements and therefore the only memory cost is the
* reference.
*/
private Object key;
/**
* The expiry time in milliseconds
*/
private long expiryTime;
/**
* The numbe of times the element has been requested and found in the cache.
*/
private long hitcount;
/**
* @return the key of this object
*/
public Object getObjectKey() {
return key;
}
/**
* @return the hit count for the element
*/
public long getHitCount() {
return hitcount;
}
}
/**
* A background daemon thread that writes objects to the file.
*/
private final class SpoolAndExpiryThread extends Thread {
public SpoolAndExpiryThread() {
super("Store " + name + " Spool Thread");
setDaemon(true);
setPriority(Thread.NORM_PRIORITY);
}
/**
* RemoteDebugger thread method.
*/
public final void run() {
spoolAndExpiryThreadMain();
}
}
/**
* @return the total size of the data file and the index file, in bytes.
*/
public final long getTotalFileSize() {
return getDataFileSize() + getIndexFileSize();
}
/**
* @return the size of the data file in bytes.
*/
public final long getDataFileSize() {
return dataFile.length();
}
/**
* The design of the layout on the data file means that there will be small gaps created when DiskElements
* are reused.
*
* @return the sparseness, measured as the percentage of space in the Data File not used for holding data
*/
public final float calculateDataFileSparseness() {
return 1 - ((float) getUsedDataSize() / (float) getDataFileSize());
}
/**
* When elements are deleted, spaces are left in the file. These spaces are tracked and are reused
* when new elements need to be written.
* <p/>
* This method indicates the actual size used for data, excluding holes. It can be compared with
* {@link #getDataFileSize()} as a measure of fragmentation.
*/
public final long getUsedDataSize() {
return totalSize;
}
/**
* @return the size of the index file, in bytes.
*/
public final long getIndexFileSize() {
if (indexFile == null) {
return 0;
} else {
return indexFile.length();
}
}
/**
* @return the file name of the data file where the disk store stores data, without any path information.
*/
public final String getDataFileName() {
return name + ".data";
}
/**
* @return the disk path, which will be dependent on the operating system
*/
public final String getDataFilePath() {
return diskPath;
}
/**
* @return the file name of the index file, which maintains a record of elements and their addresses
* on the data file, without any path information.
*/
public final String getIndexFileName() {
return name + ".index";
}
/**
* The spool thread is started when the disk store is created.
* <p/>
* It will continue to run until the {@link #dispose()} method is called,
* at which time it should be interrupted and then die.
*
* @return true if the spoolThread is still alive.
*/
public final boolean isSpoolThreadAlive() {
if (spoolAndExpiryThread == null) {
return false;
} else {
return spoolAndExpiryThread.isAlive();
}
}
private void evictLfuDiskElement() {
synchronized (diskElements) {
DiskElement diskElement = findRelativelyUnused();
diskElements.remove(diskElement.key);
notifyEvictionListeners(diskElement);
freeBlock(diskElement);
}
}
/**
* Find a "relatively" unused disk element, but not the element just added.
*/
private DiskElement findRelativelyUnused() {
LfuPolicy.Metadata[] elements = sampleElements(diskElements);
LfuPolicy.Metadata metadata = LfuPolicy.leastHit(elements, null);
return (DiskElement) metadata;
}
/**
* Uses random numbers to sample the entire map.
*
* @return an array of sampled elements
*/
private LfuPolicy.Metadata[] sampleElements(Map map) {
int[] offsets = LfuPolicy.generateRandomSample(map.size());
DiskElement[] elements = new DiskElement[offsets.length];
Iterator iterator = map.values().iterator();
for (int i = 0; i < offsets.length; i++) {
for (int j = 0; j < offsets[i]; j++) {
iterator.next();
}
elements[i] = (DiskElement) iterator.next();
}
return elements;
}
private void notifyEvictionListeners(DiskElement diskElement) {
RegisteredEventListeners listeners = cache.getCacheEventNotificationService();
// only load the element from the file if there is a listener interested in hearing about its expiration
if (listeners.hasCacheEventListeners()) {
Element element = null;
try {
element = loadElementFromDiskElement(diskElement);
cache.getCacheEventNotificationService().notifyElementEvicted(element, false);
} catch (Exception exception) {
LOG.log(Level.SEVERE, name + "Cache: Could not notify disk store eviction of " + element.getObjectKey() +
". Error was " + exception.getMessage(), exception);
}
}
}
}
The table below shows all metrics for DiskStore.java.
| Metric | Value | Description | |
|---|---|---|---|
| BLOCKS | 178.00 | Number of blocks | |
| BLOCK_COMMENT | 0.00 | Number of block comment lines | |
| COMMENTS | 329.00 | Comment lines | |
| COMMENT_DENSITY | 0.60 | Comment density | |
| COMPARISONS | 89.00 | Number of comparison operators | |
| CYCLOMATIC | 141.00 | Cyclomatic complexity | |
| DECL_COMMENTS | 56.00 | Comments in declarations | |
| DOC_COMMENT | 283.00 | Number of javadoc comment lines | |
| ELOC | 545.00 | Effective lines of code | |
| EXEC_COMMENTS | 43.00 | Comments in executable code | |
| EXITS | 126.00 | Procedure exits | |
| FUNCTIONS | 54.00 | Number of function declarations | |
| HALSTEAD_DIFFICULTY | 97.07 | Halstead difficulty | |
| HALSTEAD_EFFORT | 0.00 | Halstead effort | |
| INTERFACE_COMPLEXITY | 113.00 | 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 | 2.00 | 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 | 1.00 | 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 | 0.00 | 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 | 4.00 | 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 | 1.00 | 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 | 2.00 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| JAVA0109 | 0.00 | JAVA0109 Incorrect javadoc: no parameter 'parameter' | |
| JAVA0110 | 8.00 | 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 | 6.00 | 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 | 1.00 | JAVA0126 Method declares unchecked exception in throws | |
| JAVA0128 | 1.00 | JAVA0128 Public constructor in non-public class | |
| JAVA0130 | 1.00 | 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 | 1.00 | JAVA0136 N methods defined in class (maximum: M) | |
| JAVA0137 | 1.00 | 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 | 10.00 | JAVA0143 Synchronized method | |
| JAVA0144 | 4.00 | 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 | 1.00 | 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 | 14.00 | JAVA0166 Generic exception caught | |
| JAVA0167 | 0.00 | JAVA0167 ThreadDeath not rethrown | |
| JAVA0169 | 0.00 | JAVA0169 Unnecessary catch block: exception 'exception' | |
| JAVA0170 | 3.00 | JAVA0170 Caught exception not derived from java.lang.Exception | |
| JAVA0171 | 0.00 | JAVA0171 Unused local variable | |
| JAVA0173 | 0.00 | JAVA0173 Unused method parameter | |
| JAVA0174 | 1.00 | 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 | 10.00 | 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 | 0.00 | 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 | 0.00 | 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 | 1.00 | 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 | 2.00 | 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 | 0.00 | JAVA0285 Dereference of potentially null variable | |
| JAVA0286 | 1.00 | JAVA0286 Dereference of null variable | |
| JAVA0287 | 0.00 | JAVA0287 Unnecessary null check | |
| JAVA0288 | 0.00 | JAVA0288 Inconsistent null check | |
| LINES | 1176.00 | Number of lines in the source file | |
| LINE_COMMENT | 46.00 | Number of line comments | |
| LOC | 694.00 | Lines of code | |
| LOGICAL_LINES | 354.00 | Number of statements | |
| LOOPS | 7.00 | Number of loops | |
| NEST_DEPTH | 6.00 | Maximum nesting depth | |
| OPERANDS | 1382.00 | Number of operands | |
| OPERATORS | 2875.00 | Number of operators | |
| PARAMS | 20.00 | Number of formal parameter declarations | |
| PROGRAM_LENGTH | 4257.00 | Halstead program length | |
| PROGRAM_VOCAB | 479.00 | Halstead program vocabulary | |
| PROGRAM_VOLUME | 0.00 | Halstead program volume | |
| RETURNS | 93.00 | Number of return points from functions | |
| SIZE | 40381.00 | Size of the file in bytes | |
| UNIQUE_OPERANDS | 420.00 | Number of unique operands | |
| UNIQUE_OPERATORS | 59.00 | Number of unique operators | |
| WHITESPACE | 153.00 | Number of whitespace lines | |