package org.compass.core.converter.xsem;
import java.io.Reader;
import org.compass.core.CompassException;
import org.compass.core.config.CompassConfigurable;
import org.compass.core.config.CompassEnvironment;
import org.compass.core.config.CompassSettings;
import org.compass.core.converter.ConversionException;
import org.compass.core.xml.AliasedXmlObject;
import org.compass.core.xml.XmlObject;
/**
* An {@link XmlContentConverter} implementation that wraps the actual {@link XmlContentConverter}
* configured (based on the settings) and creates and configures a pool of {@link XmlContentConverter}s
* for both {@link #toXml(org.compass.core.xml.XmlObject)} and {@link #fromXml(String, java.io.Reader)}.
* <p/>
* The pool has a maximum capacity, to limit overhead. If all instances in the
* pool are in use and another is required, it shall block until one becomes
* available.
*
* @author kimchy
*/
public class PoolXmlContentConverterWrapper implements XmlContentConverter, CompassConfigurable {
private CompassSettings settings;
private int initialPoolSize;
private int maxPoolSize;
private transient XmlContentConverter[] pool;
private int nextAvailable = 0;
private final Object mutex = new Object();
/**
* Configures the pool used from {@link CompassEnvironment.Converter.XmlContent#MIN_POOL_SIZE} and
* {@link CompassEnvironment.Converter.XmlContent#MAX_POOL_SIZE}.
*/
public void configure(CompassSettings settings) throws CompassException {
this.settings = settings;
this.initialPoolSize = settings.getSettingAsInt(CompassEnvironment.Converter.XmlContent.MIN_POOL_SIZE, 10);
this.maxPoolSize = settings.getSettingAsInt(CompassEnvironment.Converter.XmlContent.MAX_POOL_SIZE, 30);
// warm up the pool
XmlContentConverter converter = fetchFromPool();
putInPool(converter);
}
/**
* Converts the {@link XmlObject} into raw xml by using the pool of
* {@link XmlContentConverter}s implementation.
*
* @see XmlContentConverter#toXml(org.compass.core.xml.XmlObject)
*/
public String toXml(XmlObject xmlObject) throws ConversionException {
XmlContentConverter converter = fetchFromPool();
try {
return converter.toXml(xmlObject);
} finally {
putInPool(converter);
}
}
/**
* Converts a raw xml and an alias into an {@link AliasedXmlObject} by using the pool of
* {@link XmlContentConverter}s implementation.
*
* @see XmlContentConverter#fromXml(String, java.io.Reader)
*/
public AliasedXmlObject fromXml(String alias, Reader xml) throws ConversionException {
XmlContentConverter converter = fetchFromPool();
try {
return converter.fromXml(alias, xml);
} finally {
putInPool(converter);
}
}
private XmlContentConverter fetchFromPool() {
XmlContentConverter result;
synchronized (mutex) {
if (pool == null) {
nextAvailable = -1;
pool = new XmlContentConverter[maxPoolSize];
for (int i = 0; i < initialPoolSize; i++) {
putInPool(XmlContentConverterUtils.createXmlContentConverter(settings));
}
}
while (nextAvailable < 0) {
try {
mutex.wait();
} catch (InterruptedException e) {
throw new ConversionException("Interrupted whilst waiting for a free item in the pool", e);
}
}
result = pool[nextAvailable];
nextAvailable--;
}
if (result == null) {
result = XmlContentConverterUtils.createXmlContentConverter(settings);
putInPool(result);
}
return result;
}
private void putInPool(XmlContentConverter converter) {
synchronized (mutex) {
nextAvailable++;
pool[nextAvailable] = converter;
mutex.notify();
}
}
}
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