/*
* Copyright 2012-2014 Continuuity, Inc.
*
* Licensed 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 com.continuuity.tephra.hbase98.coprocessor;
import com.continuuity.tephra.Transaction;
import com.continuuity.tephra.TransactionCodec;
import com.continuuity.tephra.TxConstants;
import com.continuuity.tephra.coprocessor.TransactionStateCache;
import com.continuuity.tephra.coprocessor.TransactionStateCacheSupplier;
import com.continuuity.tephra.hbase98.Filters;
import com.continuuity.tephra.persist.TransactionSnapshot;
import com.continuuity.tephra.util.TxUtils;
import com.google.common.base.Supplier;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.coprocessor.BaseRegionObserver;
import org.apache.hadoop.hbase.coprocessor.ObserverContext;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.FilterBase;
import org.apache.hadoop.hbase.regionserver.InternalScanner;
import org.apache.hadoop.hbase.regionserver.KeyValueScanner;
import org.apache.hadoop.hbase.regionserver.RegionScanner;
import org.apache.hadoop.hbase.regionserver.ScanType;
import org.apache.hadoop.hbase.regionserver.Store;
import org.apache.hadoop.hbase.regionserver.StoreScanner;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
import org.apache.hadoop.hbase.util.Bytes;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* {@code org.apache.hadoop.hbase.coprocessor.RegionObserver} coprocessor that handles server-side processing
* for transactions:
* <ul>
* <li>applies filtering to exclude data from invalid and in-progress transactions</li>
* <li>overrides the scanner returned for flush and compaction to drop data written by invalidated transactions,
* or expired due to TTL.</li>
* </ul>
*
* <p>In order to use this coprocessor for transactions, configure the class on any table involved in transactions,
* or on all user tables by adding the following to hbase-site.xml:
* {@code
* <property>
* <name>hbase.coprocessor.region.classes</name>
* <value>com.continuuity.tephra.hbase98.coprocessor.TransactionProcessor</value>
* </property>
* }
* </p>
*
* <p>HBase {@code Get} and {@code Scan} operations should have the current transaction serialized on to the operation
* as an attribute:
* {@code
* Transaction t = ...;
* Get get = new Get(...);
* TransactionCodec codec = new TransactionCodec();
* codec.addToOperation(get, t);
* }
* </p>
*/
public class TransactionProcessor extends BaseRegionObserver {
private static final Log LOG = LogFactory.getLog(TransactionProcessor.class);
private TransactionStateCache cache;
private final TransactionCodec txCodec;
protected Map<byte[], Long> ttlByFamily = Maps.newTreeMap(Bytes.BYTES_COMPARATOR);
protected boolean allowEmptyValues = TxConstants.ALLOW_EMPTY_VALUES_DEFAULT;
public TransactionProcessor() {
this.txCodec = new TransactionCodec();
}
/* RegionObserver implementation */
@Override
public void start(CoprocessorEnvironment e) throws IOException {
if (e instanceof RegionCoprocessorEnvironment) {
RegionCoprocessorEnvironment env = (RegionCoprocessorEnvironment) e;
Supplier<TransactionStateCache> cacheSupplier = getTransactionStateCacheSupplier(env);
this.cache = cacheSupplier.get();
HTableDescriptor tableDesc = env.getRegion().getTableDesc();
for (HColumnDescriptor columnDesc : tableDesc.getFamilies()) {
String columnTTL = columnDesc.getValue(TxConstants.PROPERTY_TTL);
long ttl = 0;
if (columnTTL != null) {
try {
ttl = Long.parseLong(columnTTL);
LOG.info("Family " + columnDesc.getNameAsString() + " has TTL of " + columnTTL);
} catch (NumberFormatException nfe) {
LOG.warn("Invalid TTL value configured for column family " + columnDesc.getNameAsString() +
", value = " + columnTTL);
}
}
ttlByFamily.put(columnDesc.getName(), ttl);
}
this.allowEmptyValues = env.getConfiguration().getBoolean(TxConstants.ALLOW_EMPTY_VALUES_KEY,
TxConstants.ALLOW_EMPTY_VALUES_DEFAULT);
}
}
protected Supplier<TransactionStateCache> getTransactionStateCacheSupplier(RegionCoprocessorEnvironment env) {
return new TransactionStateCacheSupplier(env.getConfiguration());
}
@Override
public void stop(CoprocessorEnvironment e) throws IOException {
// nothing to do
}
@Override
public void preGetOp(ObserverContext<RegionCoprocessorEnvironment> e, Get get, List<Cell> results)
throws IOException {
Transaction tx = txCodec.getFromOperation(get);
if (tx != null) {
get.setMaxVersions(tx.excludesSize() + 1);
get.setTimeRange(TxUtils.getOldestVisibleTimestamp(ttlByFamily, tx), TxUtils.getMaxVisibleTimestamp(tx));
Filter newFilter = Filters.combine(getTransactionFilter(tx), get.getFilter());
get.setFilter(newFilter);
}
}
@Override
public RegionScanner preScannerOpen(ObserverContext<RegionCoprocessorEnvironment> e, Scan scan, RegionScanner s)
throws IOException {
Transaction tx = txCodec.getFromOperation(scan);
if (tx != null) {
scan.setMaxVersions(tx.excludesSize() + 1);
scan.setTimeRange(TxUtils.getOldestVisibleTimestamp(ttlByFamily, tx), TxUtils.getMaxVisibleTimestamp(tx));
Filter newFilter = Filters.combine(getTransactionFilter(tx), scan.getFilter());
scan.setFilter(newFilter);
}
return s;
}
@Override
public InternalScanner preFlushScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Store store,
KeyValueScanner memstoreScanner, InternalScanner scanner)
throws IOException {
return createStoreScanner(c.getEnvironment(), "flush", cache.getLatestState(), store,
Collections.singletonList(memstoreScanner), ScanType.COMPACT_RETAIN_DELETES,
HConstants.OLDEST_TIMESTAMP);
}
@Override
public InternalScanner preCompactScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Store store,
List<? extends KeyValueScanner> scanners, ScanType scanType, long earliestPutTs, InternalScanner s,
CompactionRequest request)
throws IOException {
return createStoreScanner(c.getEnvironment(), "compaction", cache.getLatestState(), store, scanners,
scanType, earliestPutTs);
}
protected InternalScanner createStoreScanner(RegionCoprocessorEnvironment env, String action,
TransactionSnapshot snapshot, Store store,
List<? extends KeyValueScanner> scanners, ScanType type,
long earliestPutTs) throws IOException {
if (snapshot == null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Region " + env.getRegion().getRegionNameAsString() +
", no current transaction state found, defaulting to normal " + action + " scanner");
}
return null;
}
// construct a dummy transaction from the latest snapshot
Transaction dummyTx = TxUtils.createDummyTransaction(snapshot);
Scan scan = new Scan();
// does not current support max versions setting per family
scan.setMaxVersions(dummyTx.excludesSize() + 1);
scan.setFilter(new IncludeInProgressFilter(dummyTx.getVisibilityUpperBound(),
snapshot.getInvalid(),
getTransactionFilter(dummyTx)));
return new StoreScanner(store, store.getScanInfo(), scan, scanners,
type, store.getSmallestReadPoint(), earliestPutTs);
}
/**
* Derived classes can override this method to customize the filter used to return data visible for the current
* transaction.
* @param tx The current transaction to apply.
*/
protected Filter getTransactionFilter(Transaction tx) {
return new TransactionVisibilityFilter(tx, ttlByFamily, allowEmptyValues);
}
/**
* Filter used to include cells visible to in-progress transactions on flush and commit.
*/
static class IncludeInProgressFilter extends FilterBase {
private final long visibilityUpperBound;
private final Set<Long> invalidIds;
private final Filter txFilter;
public IncludeInProgressFilter(long upperBound, Collection<Long> invalids, Filter transactionFilter) {
this.visibilityUpperBound = upperBound;
this.invalidIds = Sets.newHashSet(invalids);
this.txFilter = transactionFilter;
}
@Override
public ReturnCode filterKeyValue(Cell cell) throws IOException {
// include all cells visible to in-progress transactions, except for those already marked as invalid
long ts = cell.getTimestamp();
if (ts > visibilityUpperBound) {
// include everything that could still be in-progress except invalids
if (invalidIds.contains(ts)) {
return ReturnCode.SKIP;
}
return ReturnCode.INCLUDE;
}
return txFilter.filterKeyValue(cell);
}
}
}