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package org.apache.jasper.runtime;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;
import javax.servlet.ServletConfig;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.Tag;
import org.apache.jasper.Constants;
/**
* Thread-local based pool of tag handlers that can be reused.
*
* @author Jan Luehe
* @author Costin Manolache
*/
public class PerThreadTagHandlerPool extends TagHandlerPool {
private int maxSize;
// For cleanup
private Vector perThreadDataVector;
private ThreadLocal perThread;
private static class PerThreadData {
Tag handlers[];
int current;
}
/**
* Constructs a tag handler pool with the default capacity.
*/
public PerThreadTagHandlerPool() {
super();
perThreadDataVector = new Vector();
}
protected void init(ServletConfig config) {
maxSize = Constants.MAX_POOL_SIZE;
String maxSizeS = getOption(config, OPTION_MAXSIZE, null);
if (maxSizeS != null) {
maxSize = Integer.parseInt(maxSizeS);
if (maxSize < 0) {
maxSize = Constants.MAX_POOL_SIZE;
}
}
perThread = new ThreadLocal() {
protected Object initialValue() {
PerThreadData ptd = new PerThreadData();
ptd.handlers = new Tag[maxSize];
ptd.current = -1;
perThreadDataVector.addElement(ptd);
return ptd;
}
};
}
/**
* Gets the next available tag handler from this tag handler pool,
* instantiating one if this tag handler pool is empty.
*
* @param handlerClass Tag handler class
*
* @return Reused or newly instantiated tag handler
*
* @throws JspException if a tag handler cannot be instantiated
*/
public Tag get(Class handlerClass) throws JspException {
PerThreadData ptd = (PerThreadData)perThread.get();
if(ptd.current >=0 ) {
return ptd.handlers[ptd.current--];
} else {
try {
return (Tag) handlerClass.newInstance();
} catch (Exception e) {
throw new JspException(e.getMessage(), e);
}
}
}
/**
* Adds the given tag handler to this tag handler pool, unless this tag
* handler pool has already reached its capacity, in which case the tag
* handler's release() method is called.
*
* @param handler Tag handler to add to this tag handler pool
*/
public void reuse(Tag handler) {
PerThreadData ptd=(PerThreadData)perThread.get();
if (ptd.current < (ptd.handlers.length - 1)) {
ptd.handlers[++ptd.current] = handler;
} else {
handler.release();
}
}
/**
* Calls the release() method of all tag handlers in this tag handler pool.
*/
public void release() {
Enumeration enumeration = perThreadDataVector.elements();
while (enumeration.hasMoreElements()) {
PerThreadData ptd = (PerThreadData)enumeration.nextElement();
if (ptd.handlers != null) {
for (int i=ptd.current; i>=0; i--) {
if (ptd.handlers[i] != null) {
ptd.handlers[i].release();
}
}
}
}
}
}
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