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/*
* 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.datacache;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;
import org.apache.commons.collections.map.LinkedMap;
import org.apache.openjpa.kernel.FetchConfiguration;
import org.apache.openjpa.kernel.LockLevels;
import org.apache.openjpa.kernel.OpenJPAStateManager;
import org.apache.openjpa.kernel.QueryContext;
import org.apache.openjpa.kernel.StoreContext;
import org.apache.openjpa.kernel.StoreQuery;
import org.apache.openjpa.kernel.exps.AggregateListener;
import org.apache.openjpa.kernel.exps.FilterListener;
import org.apache.openjpa.lib.rop.ListResultObjectProvider;
import org.apache.openjpa.lib.rop.ResultObjectProvider;
import org.apache.openjpa.meta.ClassMetaData;
import org.apache.openjpa.meta.JavaTypes;
import org.apache.openjpa.meta.MetaDataRepository;
import org.apache.openjpa.util.ObjectNotFoundException;
import serp.util.Numbers;
/**
* A {@link StoreQuery} implementation that caches the OIDs involved in
* the query, and can determine whether or not the query has been dirtied.
*
* @author Patrick Linskey
* @since 0.2.5.0
*/
public class QueryCacheStoreQuery
implements StoreQuery {
private final StoreQuery _query;
private final QueryCache _cache;
private StoreContext _sctx;
private MetaDataRepository _repos;
/**
* Create a new instance that delegates to query if no
* cached results are available.
*/
public QueryCacheStoreQuery(StoreQuery query, QueryCache cache) {
_query = query;
_cache = cache;
}
/**
* Return the {@link QueryCache} that this object is associated with.
*/
public QueryCache getCache() {
return _cache;
}
/**
* Delegate.
*/
public StoreQuery getDelegate() {
return _query;
}
/**
* Look in the query cache for a result for the given query
* key. Only look if this query is being executed outside a
* transaction or in a transaction with IgnoreChanges set to true
* or in a transaction with IgnoreChanges set to false but in which
* none of the classes involved in this query have been touched.
* Caching is not used when using object locking.
* This is because we must obtain locks on the
* data, and it is likely that making n trips to the database to
* make the locks will be slower than running the query against
* the database.
* If the fetch configuration has query caching disabled,
* then this method returns null.
* Return the list if we meet the above criteria and if a list
* is found for qk. Else, return
* null.
* This implementation means that queries against the cache
* are of READ_COMMITTED isolation level. It'd be nice to support
* READ_SERIALIZABLE -- to do so, we'd just return false when in
* a transaction.
*/
private List checkCache(QueryKey qk) {
if (qk == null)
return null;
FetchConfiguration fetch = getContext().getFetchConfiguration();
if (!fetch.getQueryCacheEnabled())
return null;
if (fetch.getReadLockLevel() > LockLevels.LOCK_NONE)
return null;
// get the cached data
QueryResult res = _cache.get(qk);
if (res == null)
return null;
if (res.isEmpty())
return Collections.EMPTY_LIST;
int projs = getContext().getProjectionAliases().length;
if (projs == 0) {
// make sure the data cache contains the oids for the query result;
// if it doesn't, then using the result could be slower than not
// using it because of the individual by-oid lookups
ClassMetaData meta = _repos.getMetaData(getContext().
getCandidateType(), _sctx.getClassLoader(), true);
if (meta.getDataCache() == null)
return null;
BitSet idxs = meta.getDataCache().containsAll(res);
// eventually we should optimize this to figure out how many objects
// the cache is missing and if only a few do a bulk fetch for them
int len = idxs.length();
if (len < res.size())
return null;
for (int i = 0; i < len; i++)
if (!idxs.get(i))
return null;
}
return new CachedList(res, projs != 0, _sctx);
}
/**
* Wrap the result object provider returned by our delegate in a
* caching provider.
*/
private ResultObjectProvider wrapResult(ResultObjectProvider rop,
QueryKey key) {
if (key == null)
return rop;
return new CachingResultObjectProvider(rop, getContext().
getProjectionAliases().length > 0, key);
}
/**
* Copy a projection element for caching / returning.
*/
private static Object copyProjection(Object obj, StoreContext ctx) {
if (obj == null)
return null;
switch (JavaTypes.getTypeCode(obj.getClass())) {
case JavaTypes.STRING:
case JavaTypes.BOOLEAN_OBJ:
case JavaTypes.BYTE_OBJ:
case JavaTypes.CHAR_OBJ:
case JavaTypes.DOUBLE_OBJ:
case JavaTypes.FLOAT_OBJ:
case JavaTypes.INT_OBJ:
case JavaTypes.LONG_OBJ:
case JavaTypes.SHORT_OBJ:
case JavaTypes.BIGDECIMAL:
case JavaTypes.BIGINTEGER:
case JavaTypes.OID:
return obj;
case JavaTypes.DATE:
return ((Date) obj).clone();
case JavaTypes.LOCALE:
return ((Locale) obj).clone();
default:
if (obj instanceof CachedObjectId)
return fromObjectId(((CachedObjectId) obj).oid, ctx);
Object oid = ctx.getObjectId(obj);
if (oid != null)
return new CachedObjectId(oid);
return obj;
}
}
/**
* Return the result object based on its cached oid.
*/
private static Object fromObjectId(Object oid, StoreContext sctx) {
if (oid == null)
return null;
Object obj = sctx.find(oid, null, null, null, 0);
if (obj == null)
throw new ObjectNotFoundException(oid);
return obj;
}
public Object writeReplace()
throws ObjectStreamException {
return _query;
}
public QueryContext getContext() {
return _query.getContext();
}
public void setContext(QueryContext qctx) {
_query.setContext(qctx);
_sctx = qctx.getStoreContext();
_repos = _sctx.getConfiguration().getMetaDataRepositoryInstance();
}
public boolean setQuery(Object query) {
return _query.setQuery(query);
}
public FilterListener getFilterListener(String tag) {
return _query.getFilterListener(tag);
}
public AggregateListener getAggregateListener(String tag) {
return _query.getAggregateListener(tag);
}
public Object newCompilationKey() {
return _query.newCompilationKey();
}
public Object newCompilation() {
return _query.newCompilation();
}
public void populateFromCompilation(Object comp) {
_query.populateFromCompilation(comp);
}
public void invalidateCompilation() {
_query.invalidateCompilation();
}
public boolean supportsDataStoreExecution() {
return _query.supportsDataStoreExecution();
}
public boolean supportsInMemoryExecution() {
return _query.supportsInMemoryExecution();
}
public Executor newInMemoryExecutor(ClassMetaData meta, boolean subs) {
return _query.newInMemoryExecutor(meta, subs);
}
public Executor newDataStoreExecutor(ClassMetaData meta, boolean subs) {
Executor ex = _query.newDataStoreExecutor(meta, subs);
return new QueryCacheExecutor(ex, meta, subs);
}
public boolean supportsAbstractExecutors() {
return _query.supportsAbstractExecutors();
}
public boolean requiresCandidateType() {
return _query.requiresCandidateType();
}
public boolean requiresParameterDeclarations() {
return _query.requiresParameterDeclarations();
}
public boolean supportsParameterDeclarations() {
return _query.supportsParameterDeclarations();
}
public Object evaluate(Object value, Object ob, Object[] params,
OpenJPAStateManager sm) {
return _query.evaluate(value, ob, params, sm);
}
/**
* Caching executor.
*/
private static class QueryCacheExecutor
implements Executor {
private final Executor _ex;
private final Class _candidate;
private final boolean _subs;
public QueryCacheExecutor(Executor ex, ClassMetaData meta,
boolean subs) {
_ex = ex;
_candidate = (meta == null) ? null : meta.getDescribedType();
_subs = subs;
}
public ResultObjectProvider executeQuery(StoreQuery q, Object[] params,
Range range) {
QueryCacheStoreQuery cq = (QueryCacheStoreQuery) q;
QueryKey key = QueryKey.newInstance(cq.getContext(),
_ex.isPacking(q), params, _candidate, _subs, range.start,
range.end);
List cached = cq.checkCache(key);
if (cached != null)
return new ListResultObjectProvider(cached);
ResultObjectProvider rop = _ex.executeQuery(cq.getDelegate(),
params, range);
return cq.wrapResult(rop, key);
}
/**
* Clear the cached queries associated with the access path
* classes in the query. This is done when bulk operations
* (such as deletes or updates) are performed so that the
* cache remains up-to-date.
*/
private void clearAccessPath(StoreQuery q) {
if (q == null)
return;
ClassMetaData[] cmd = getAccessPathMetaDatas(q);
if (cmd == null || cmd.length == 0)
return;
List classes = new ArrayList(cmd.length);
for (int i = 0; i < cmd.length; i++)
classes.add(cmd[i].getDescribedType());
// evict from the query cache
QueryCacheStoreQuery cq = (QueryCacheStoreQuery) q;
cq.getCache().onTypesChanged(new TypesChangedEvent
(q.getContext(), classes));
// evict from the data cache
for (int i = 0; i < cmd.length; i++) {
if (cmd[i].getDataCache() != null)
cmd[i].getDataCache().removeAll(
cmd[i].getDescribedType(), true);
}
}
public Number executeDelete(StoreQuery q, Object[] params) {
try {
return _ex.executeDelete(unwrap(q), params);
} finally {
clearAccessPath(q);
}
}
public Number executeUpdate(StoreQuery q, Object[] params) {
try {
return _ex.executeUpdate(unwrap(q), params);
} finally {
clearAccessPath(q);
}
}
public String[] getDataStoreActions(StoreQuery q, Object[] params,
Range range) {
return EMPTY_STRINGS;
}
public void validate(StoreQuery q) {
_ex.validate(unwrap(q));
}
public void getRange(StoreQuery q, Object[] params, Range range) {
_ex.getRange(q, params, range);
}
public Object getOrderingValue(StoreQuery q, Object[] params,
Object resultObject, int orderIndex) {
return _ex.getOrderingValue(unwrap(q), params, resultObject,
orderIndex);
}
public boolean[] getAscending(StoreQuery q) {
return _ex.getAscending(unwrap(q));
}
public boolean isPacking(StoreQuery q) {
return _ex.isPacking(unwrap(q));
}
public String getAlias(StoreQuery q) {
return _ex.getAlias(unwrap(q));
}
public Class getResultClass(StoreQuery q) {
return _ex.getResultClass(unwrap(q));
}
public String[] getProjectionAliases(StoreQuery q) {
return _ex.getProjectionAliases(unwrap(q));
}
public Class[] getProjectionTypes(StoreQuery q) {
return _ex.getProjectionTypes(unwrap(q));
}
public ClassMetaData[] getAccessPathMetaDatas(StoreQuery q) {
return _ex.getAccessPathMetaDatas(unwrap(q));
}
public int getOperation(StoreQuery q) {
return _ex.getOperation(unwrap(q));
}
public boolean isAggregate(StoreQuery q) {
return _ex.isAggregate(unwrap(q));
}
public boolean hasGrouping(StoreQuery q) {
return _ex.hasGrouping(unwrap(q));
}
public LinkedMap getParameterTypes(StoreQuery q) {
return _ex.getParameterTypes(unwrap(q));
}
public Map getUpdates(StoreQuery q) {
return _ex.getUpdates(unwrap(q));
}
private static StoreQuery unwrap(StoreQuery q) {
return ((QueryCacheStoreQuery) q).getDelegate();
}
}
/**
* Result list implementation for a cached query result. Package-protected
* for testing.
*/
public static class CachedList
extends AbstractList
implements Serializable {
private final QueryResult _res;
private final boolean _proj;
private final StoreContext _sctx;
public CachedList(QueryResult res, boolean proj, StoreContext ctx) {
_res = res;
_proj = proj;
_sctx = ctx;
}
public Object get(int idx) {
if (!_proj)
return fromObjectId(_res.get(idx), _sctx);
Object[] cached = (Object[]) _res.get(idx);
if (cached == null)
return null;
Object[] uncached = new Object[cached.length];
for (int i = 0; i < cached.length; i++)
uncached[i] = copyProjection(cached[i], _sctx);
return uncached;
}
public int size() {
return _res.size();
}
public Object writeReplace()
throws ObjectStreamException {
return new ArrayList(this);
}
}
/**
* A wrapper around a {@link ResultObjectProvider} that builds up a list of
* all the OIDs in this list and registers that list with the
* query cache. Abandons monitoring and registering if one of the classes
* in the access path is modified while the query results are being loaded.
*/
private class CachingResultObjectProvider
implements ResultObjectProvider, TypesChangedListener {
private final ResultObjectProvider _rop;
private final boolean _proj;
private final QueryKey _qk;
private final TreeMap _data = new TreeMap();
private boolean _maintainCache = true;
private int _pos = -1;
// used to determine list size without necessarily calling size(),
// which may require a DB trip or return Integer.MAX_VALUE
private int _max = -1;
private int _size = Integer.MAX_VALUE;
/**
* Constructor. Supply delegate result provider and our query key.
*/
public CachingResultObjectProvider(ResultObjectProvider rop,
boolean proj, QueryKey key) {
_rop = rop;
_proj = proj;
_qk = key;
_cache.addTypesChangedListener(this);
}
/**
* Stop caching.
*/
private void abortCaching() {
if (!_maintainCache)
return;
// this can be called via an event from another thread
synchronized (this) {
// it's important that we set this flag first so that any
// subsequent calls to this object are bypassed.
_maintainCache = false;
_cache.removeTypesChangedListener(this);
_data.clear();
}
}
/**
* Check whether we've buffered all results, while optionally adding
* the given result.
*/
private void checkFinished(Object obj, boolean result) {
// this can be called at the same time as abortCaching via
// a types changed event
boolean finished = false;
synchronized (this) {
if (_maintainCache) {
if (result) {
Integer index = Numbers.valueOf(_pos);
if (!_data.containsKey(index)) {
Object cached;
if (obj == null)
cached = null;
else if (!_proj)
cached = _sctx.getObjectId(obj);
else {
Object[] arr = (Object[]) obj;
Object[] cp = new Object[arr.length];
for (int i = 0; i < arr.length; i++)
cp[i] = copyProjection(arr[i], _sctx);
cached = cp;
}
if (cached != null)
_data.put(index, cached);
}
}
finished = _size == _data.size();
}
}
if (finished) {
// an abortCaching call can sneak in here via onExpire; the
// cache is locked during event firings, so the lock here will
// wait for it (or will force the next firing to wait)
_cache.writeLock();
try {
// make sure we didn't abort
if (_maintainCache) {
QueryResult res = null;
synchronized (this) {
res = new QueryResult(_qk, _data.values());
}
_cache.put(_qk, res);
abortCaching();
}
}
finally {
_cache.writeUnlock();
}
}
}
public boolean supportsRandomAccess() {
return _rop.supportsRandomAccess();
}
public void open()
throws Exception {
_rop.open();
}
public Object getResultObject()
throws Exception {
Object obj = _rop.getResultObject();
checkFinished(obj, true);
return obj;
}
public boolean next()
throws Exception {
_pos++;
boolean next = _rop.next();
if (!next && _pos == _max + 1) {
_size = _pos;
checkFinished(null, false);
} else if (next && _pos > _max)
_max = _pos;
return next;
}
public boolean absolute(int pos)
throws Exception {
_pos = pos;
boolean valid = _rop.absolute(pos);
if (!valid && _pos == _max + 1) {
_size = _pos;
checkFinished(null, false);
} else if (valid && _pos > _max)
_max = _pos;
return valid;
}
public int size()
throws Exception {
if (_size != Integer.MAX_VALUE)
return _size;
int size = _rop.size();
_size = size;
checkFinished(null, false);
return size;
}
public void reset()
throws Exception {
_rop.reset();
_pos = -1;
}
public void close()
throws Exception {
abortCaching();
_rop.close();
}
public void handleCheckedException(Exception e) {
_rop.handleCheckedException(e);
}
public void onTypesChanged(TypesChangedEvent ev) {
if (_qk.changeInvalidatesQuery(ev.getTypes()))
abortCaching();
}
}
/**
* Struct to recognize cached oids.
*/
private static class CachedObjectId {
public final Object oid;
public CachedObjectId (Object oid)
{
this.oid = oid;
}
}
}
