com.sun.gjc.spi.base.datastructure.LRUCacheImpl Maven / Gradle / Ivy
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// Portions Copyright [2019] Payara Foundation and/or affiliates
package com.sun.gjc.spi.base.datastructure;
import com.sun.gjc.monitoring.StatementCacheProbeProvider;
import com.sun.gjc.spi.base.CacheObjectKey;
import com.sun.gjc.spi.base.PreparedStatementWrapper;
import com.sun.logging.LogDomains;
import org.glassfish.resourcebase.resources.api.PoolInfo;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Shalini M
*/
public class LRUCacheImpl implements Cache {
/**
* Stores the objects for statement caching
*/
private Map list;
/**
* Size of the cache
*/
private int maxSize ;
protected static final Logger _logger;
private StatementCacheProbeProvider probeProvider = null;
private PoolInfo poolInfo;
static {
_logger = LogDomains.getLogger(LRUCacheImpl.class, LogDomains.RSR_LOGGER);
}
public LRUCacheImpl(PoolInfo poolInfo, int maxSize){
this.maxSize = maxSize;
this.poolInfo = poolInfo;
list = new LinkedHashMap();
try {
probeProvider = new StatementCacheProbeProvider();
} catch(Exception ex) {
//TODO logger
}
}
/**
* Check if an entry is found for this key object. If found, the entry is
* put in the result object and back into the list.
*
* @param key key whose mapping entry is to be checked.
* @return result object that contains the key with the entry if not
* null when
* (1) object not found in cache
*/
@Override
public Object checkAndUpdateCache(CacheObjectKey key) {
Object result = null;
CacheEntry entry = list.get(key);
if(entry != null) {
//Cache hit
result = entry.entryObj;
if(_logger.isLoggable(Level.FINEST)) {
_logger.finest("Cache Hit");
}
//TODO-SC Busy cache hits?
probeProvider.statementCacheHitEvent(poolInfo.getName(), poolInfo.getApplicationName(), poolInfo.getModuleName());
} else {
//Cache miss
if(_logger.isLoggable(Level.FINEST)) {
_logger.finest("Cache Miss");
}
probeProvider.statementCacheMissEvent(poolInfo.getName(), poolInfo.getApplicationName(), poolInfo.getModuleName());
}
return result;
}
/**
* Add the key and entry value into the cache.
* @param key key that contains the sql string and its type (PS/CS)
* @param o entry that is the wrapper of PreparedStatement or
* CallableStatement
* @param force If the already existing key is to be overwritten
*/
@Override
public void addToCache(CacheObjectKey key, Object o, boolean force) {
if(force || !list.containsKey(key)){
//overwrite or if not already found in cache
if(list.size() >= maxSize){
purge();
}
CacheEntry entry = new CacheEntry(o);
list.put(key, entry);
}
}
/**
* Clears the statement cache
*/
@Override
public void clearCache(){
if (_logger.isLoggable(Level.FINE)) {
_logger.fine("clearing objects in cache");
}
list.clear();
}
@Override
public void flushCache() {
while(!list.isEmpty()){
purge();
}
}
@Override
public void purge() {
Iterator keyIterator = list.keySet().iterator();
while(keyIterator.hasNext()){
CacheObjectKey key = (CacheObjectKey)keyIterator.next();
CacheEntry entry = list.get(key);
try{
//TODO Move to a more generic Contract and invoke close()
//PreparedStatementWrapper could implement the contract instead
PreparedStatementWrapper ps = (PreparedStatementWrapper)entry.entryObj;
ps.setCached(false);
ps.close();
}catch(SQLException e){
//ignore
}
keyIterator.remove();
break;
}
}
// Used only for purging the bad statements.
@Override
public void purge(Object obj) {
PreparedStatementWrapper tmpPS = (PreparedStatementWrapper) obj;
Iterator keyIterator = list.keySet().iterator();
while(keyIterator.hasNext()){
CacheObjectKey key = (CacheObjectKey)keyIterator.next();
CacheEntry entry = list.get(key);
try{
//TODO Move to a more generic Contract and invoke close()
//PreparedStatementWrapper could implement the contract instead
PreparedStatementWrapper ps = (PreparedStatementWrapper)entry.entryObj;
if(ps.equals(tmpPS)) {
//Found the entry in the cache. Remove this entry.
if(_logger.isLoggable(Level.FINEST)) {
_logger.log(Level.FINEST, "Purging an entry from cache");
}
ps.setCached(false);
ps.close();
}
}catch(SQLException e){
//ignore
}
keyIterator.remove();
break;
}
}
/**
* Returns the number of entries in the statement cache
* @return has integer value
*/
@Override
public int getSize() {
return list.size();
}
public int getMaxSize() {
return maxSize;
}
/**
* Cache object that has an entry. This is used to put inside the
* statement cache.
*/
public static class CacheEntry{
private Object entryObj;
public CacheEntry(Object o){
this.entryObj = o;
}
}
/*public Set getObjects(){
//TODO-SC-DEFER can the set be "type-safe"
Set set = new HashSet();
for(CacheEntry entry : list.values()){
set.add(entry.entryObj);
}
return set;
}*/
@Override
public boolean isSynchronized() {
return false;
}
}