/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.openjpa.jdbc.kernel;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.commons.lang.StringUtils;
import org.apache.openjpa.conf.OpenJPAConfiguration;
import org.apache.openjpa.kernel.FetchConfiguration;
import org.apache.openjpa.kernel.PreparedQuery;
import org.apache.openjpa.kernel.PreparedQueryCache;
import org.apache.openjpa.kernel.Query;
import org.apache.openjpa.kernel.QueryHints;
import org.apache.openjpa.kernel.QueryLanguages;
import org.apache.openjpa.kernel.QueryStatistics;
import org.apache.openjpa.lib.conf.Configuration;
import org.apache.openjpa.lib.log.Log;
import org.apache.openjpa.lib.util.Localizer;
import org.apache.openjpa.util.CacheMap;
/**
* An implementation of the cache of {@link PreparedQuery prepared queries}.
*
* @author Pinaki Poddar
*
* @since 2.0.0
*
* @nojavadoc
*/
public class PreparedQueryCacheImpl implements PreparedQueryCache {
private static final String PATTERN_SEPARATOR = "\\;";
// Key: Query identifier
private final Map<String, PreparedQuery> _delegate;
// Key: Query identifier Value: Reason why excluded
private final Map<String, Exclusion> _uncachables;
private final List<Exclusion> _exclusionPatterns;
private QueryStatistics<String> _stats;
private boolean _statsEnabled;
private Lock _writeLock;
private Lock _readLock;
private Log _log;
private static Localizer _loc = Localizer.forPackage(PreparedQueryCacheImpl.class);
public PreparedQueryCacheImpl() {
_delegate = new CacheMap();
_uncachables = new CacheMap();
_exclusionPatterns = new ArrayList<Exclusion>();
ReentrantReadWriteLock _rwl = new ReentrantReadWriteLock();
_writeLock = _rwl.writeLock();
_readLock = _rwl.readLock();
}
public Boolean register(String id, Query query, FetchConfiguration hints) {
if (id == null
|| query == null
|| QueryLanguages.LANG_SQL.equals(query.getLanguage())
|| QueryLanguages.LANG_METHODQL.equals(query.getLanguage())
|| isHinted(hints, QueryHints.HINT_IGNORE_PREPARED_QUERY)
|| isHinted(hints, QueryHints.HINT_INVALIDATE_PREPARED_QUERY))
return Boolean.FALSE;
if (Boolean.FALSE.equals(isCachable(id)))
return Boolean.FALSE;
PreparedQuery cached = get(id);
if (cached != null)
return null; // implies that it is already cached
PreparedQuery newEntry = new PreparedQueryImpl(id, query);
return cache(newEntry);
}
public Map<String,String> getMapView() {
lock(false);
try {
Map<String, String> view = new TreeMap<String, String>();
for (Map.Entry<String, PreparedQuery> entry : _delegate.entrySet())
view.put(entry.getKey(), entry.getValue().getTargetQuery());
return view;
} finally {
unlock(false);
}
}
/**
* Cache the given query keyed by its identifier. Does not cache if the
* identifier matches any exclusion pattern or has been marked as
* non-cachable. Also register the identifier as not cachable against
* the matched exclusion pattern.
*/
public boolean cache(PreparedQuery q) {
lock(false);
try {
String id = q.getIdentifier();
if (Boolean.FALSE.equals(isCachable(id))) {
if (_log != null && _log.isTraceEnabled())
_log.trace(_loc.get("prepared-query-not-cachable", id));
return false;
}
Exclusion exclusion = getMatchedExclusionPattern(id);
if (exclusion != null) {
markUncachable(id, exclusion);
return false;
}
_delegate.put(id, q);
if (_log != null && _log.isTraceEnabled())
_log.trace(_loc.get("prepared-query-cached", id));
return true;
} finally {
unlock(false);
}
}
public PreparedQuery initialize(String key, Object result) {
PreparedQuery pq = get(key);
if (pq == null)
return null;
Exclusion exclusion = pq.initialize(result);
if (exclusion != null) {
markUncachable(key, exclusion);
return null;
}
return pq;
}
public boolean invalidate(String id) {
lock(false);
try {
if (_log != null && _log.isTraceEnabled())
_log.trace(_loc.get("prepared-query-invalidate", id));
boolean rc = _delegate.remove(id) != null;
if (_statsEnabled && rc) {
_stats.recordEviction(id);
}
return rc;
} finally {
unlock(false);
}
}
public PreparedQuery get(String id) {
lock(true);
try {
return _delegate.get(id);
} finally {
unlock(true);
}
}
public Boolean isCachable(String id) {
lock(true);
try {
if (_uncachables.containsKey(id))
return Boolean.FALSE;
if (_delegate.containsKey(id))
return Boolean.TRUE;
return null;
} finally {
unlock(true);
}
}
public PreparedQuery markUncachable(String id, Exclusion exclusion) {
lock(false);
try {
if (_uncachables.put(id, exclusion) == null) {
if (_log != null && _log.isTraceEnabled())
_log.trace(_loc.get("prepared-query-uncache", id, exclusion));
}
PreparedQuery pq = _delegate.remove(id);
if (_statsEnabled && pq != null) {
_stats.recordEviction(id);
}
return pq;
} finally {
unlock(false);
}
}
public Exclusion isExcluded(String id) {
return getMatchedExclusionPattern(id);
}
public void setExcludes(String excludes) {
lock(false);
try {
if (StringUtils.isEmpty(excludes))
return;
String[] patterns = excludes.split(PATTERN_SEPARATOR);
for (String pattern : patterns)
addExclusionPattern(pattern);
} finally {
unlock(false);
}
}
public List<Exclusion> getExcludes() {
return Collections.unmodifiableList(_exclusionPatterns);
}
/**
* Adds a pattern for exclusion. Any query cached currently whose identifier
* matches the given pattern will be marked invalidated as a side-effect.
*/
public void addExclusionPattern(String pattern) {
lock(false);
try {
String reason = _loc.get("prepared-query-excluded-by-user", pattern).getMessage();
Exclusion exclusion = new WeakExclusion(pattern, reason);
_exclusionPatterns.add(exclusion);
Collection<String> invalidKeys = getMatchedKeys(pattern, _delegate.keySet());
for (String invalidKey : invalidKeys) {
Exclusion invalid = new WeakExclusion(invalidKey, reason);
markUncachable(invalidKey, invalid);
}
} finally {
unlock(false);
}
}
/**
* Removes a pattern for exclusion. Any query identifier marked as not
* cachable due to the given pattern will now be removed from the list of
* uncachables as a side-effect.
*/
public void removeExclusionPattern(String pattern) {
lock(false);
try {
Exclusion exclusion = new WeakExclusion(pattern, null);
_exclusionPatterns.remove(exclusion);
Collection<String> reborns = getMatchedKeys(pattern, _uncachables);
for (String rebornKey : reborns) {
_uncachables.remove(rebornKey);
if (_log != null && _log.isTraceEnabled())
_log.trace(_loc.get("prepared-query-remove-pattern", pattern, rebornKey));
}
} finally {
unlock(false);
}
}
public QueryStatistics<String> getStatistics() {
return _stats;
}
/**
* Gets the pattern that matches the given identifier.
*/
private Exclusion getMatchedExclusionPattern(String id) {
for (Exclusion pattern : _exclusionPatterns)
if (pattern.matches(id))
return pattern;
return null;
}
/**
* Gets the keys of the given map whose values match the given pattern.
*/
private Collection<String> getMatchedKeys(String pattern, Map<String,Exclusion> map) {
List<String> result = new ArrayList<String>();
for (Map.Entry<String, Exclusion> entry : map.entrySet()) {
Exclusion exclusion = entry.getValue();
if (!exclusion.isStrong() && exclusion.matches(pattern)) {
result.add(entry.getKey());
}
}
return result;
}
/**
* Gets the elements of the given list which match the given pattern.
*/
private Collection<String> getMatchedKeys(String pattern, Collection<String> coll) {
List<String> result = new ArrayList<String>();
for (String key : coll) {
if (matches(pattern, key)) {
result.add(key);
}
}
return result;
}
/**
* Note: Care needs to be taken so that a read lock is <b>never</b> held while requesting a write lock. This will
* result in a deadlock.
*
* @param readOnly
* - If true, a read lock will be acquired. Else a write lock will be acquired.
*/
protected void lock(boolean readOnly) {
if (readOnly == true) {
_readLock.lock();
} else {
_writeLock.lock();
}
}
/**
* @param readOnly
* - If true, the read lock will be released. Else a write lock will be released.
*/
protected void unlock(boolean readOnly) {
if (readOnly == true) {
_readLock.unlock();
} else {
_writeLock.unlock();
}
}
boolean matches(String pattern, String target) {
return target != null && (target.equals(pattern)
|| target.matches(pattern));
}
boolean isHinted(FetchConfiguration fetch, String hint) {
if (fetch == null)
return false;
Object result = fetch.getHint(hint);
return result != null && "true".equalsIgnoreCase(result.toString());
}
public void clear() {
_delegate.clear();
_stats.clear();
}
public void setEnableStatistics(boolean enable){
_statsEnabled = enable;
}
public boolean getEnableStatistics(){
return _statsEnabled;
}
//-------------------------------------------------------
// Configurable contract
//-------------------------------------------------------
public void setConfiguration(Configuration conf) {
_log = conf.getLog(OpenJPAConfiguration.LOG_RUNTIME);
}
public void startConfiguration() {
}
public void endConfiguration() {
_stats = _statsEnabled ? new QueryStatistics.Default<String>() :
new QueryStatistics.None<String>();
}
/**
* An immutable abstract pattern for exclusion.
*
*/
private static abstract class ExclusionPattern implements PreparedQueryCache.Exclusion {
private final boolean _strong;
private final String _pattern;
private final String _reason;
private static Localizer _loc = Localizer.forPackage(PreparedQueryCacheImpl.class);
private static String STRONG = _loc.get("strong-exclusion").getMessage();
private static String WEAK = _loc.get("weak-exclusion").getMessage();
public ExclusionPattern(boolean strong, String pattern, String reason) {
super();
this._strong = strong;
this._pattern = pattern;
this._reason = reason;
}
public String getPattern() {
return _pattern;
}
public String getReason() {
return _reason;
}
public boolean isStrong() {
return _strong;
}
public boolean matches(String id) {
return _pattern != null && (_pattern.equals(id) || _pattern.matches(id));
}
/**
* Equals by strength and pattern (not by reason).
*/
@Override
public final boolean equals(Object other) {
if (other == this)
return true;
if (!(other instanceof Exclusion))
return false;
Exclusion that = (Exclusion)other;
return this._strong == that.isStrong()
&& StringUtils.equals(this._pattern, that.getPattern());
}
@Override
public int hashCode() {
return (_strong ? 1 : 0)
+ (_pattern == null ? 0 : _pattern.hashCode());
}
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append(" ").append(_strong ? STRONG : WEAK).append(". ");
if (_reason != null)
buf.append(_reason);
return buf.toString();
}
}
/**
* Strong exclusion.
*
*/
public static class StrongExclusion extends ExclusionPattern {
public StrongExclusion(String pattern, String reason) {
super(true, pattern, reason);
}
}
/**
* Weak exclusion.
*
*/
public static class WeakExclusion extends ExclusionPattern {
public WeakExclusion(String pattern, String reason) {
super(false, pattern, reason);
}
}
}