/*
* Copyright © 2015-2016 Cask Data, 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 co.cask.tephra.hbase11.coprocessor;
import co.cask.tephra.Transaction;
import co.cask.tephra.TransactionCodec;
import co.cask.tephra.TxConstants;
import co.cask.tephra.coprocessor.TransactionStateCache;
import co.cask.tephra.coprocessor.TransactionStateCacheSupplier;
import co.cask.tephra.persist.TransactionVisibilityState;
import co.cask.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.CellUtil;
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.Delete;
import org.apache.hadoop.hbase.client.Durability;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.OperationWithAttributes;
import org.apache.hadoop.hbase.client.Put;
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.regionserver.wal.WALEdit;
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.NavigableSet;
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>co.cask.tephra.hbase10.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;
protected boolean readNonTxnData = TxConstants.DEFAULT_READ_NON_TX_DATA;
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);
this.readNonTxnData = Boolean.valueOf(tableDesc.getValue(TxConstants.READ_NON_TX_DATA));
if (readNonTxnData) {
LOG.info("Reading pre-existing data enabled for table " + tableDesc.getNameAsString());
}
}
}
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 = getFromOperation(get);
if (tx != null) {
projectFamilyDeletes(get);
get.setMaxVersions();
get.setTimeRange(TxUtils.getOldestVisibleTimestamp(ttlByFamily, tx, readNonTxnData),
TxUtils.getMaxVisibleTimestamp(tx));
Filter newFilter = getTransactionFilter(tx, ScanType.USER_SCAN, get.getFilter());
get.setFilter(newFilter);
}
}
@Override
public void preDelete(ObserverContext<RegionCoprocessorEnvironment> e, Delete delete, WALEdit edit,
Durability durability) throws IOException {
// Translate deletes into our own delete tombstones
// Since HBase deletes cannot be undone, we need to translate deletes into special puts, which allows
// us to rollback the changes (by a real delete) if the transaction fails
// Deletes that are part of a transaction rollback do not need special handling.
// They will never be rolled back, so are performed as normal HBase deletes.
if (delete.getAttribute(TxConstants.TX_ROLLBACK_ATTRIBUTE_KEY) != null) {
return;
}
// Other deletes are client-initiated and need to be translated into our own tombstones
// TODO: this should delegate to the DeleteStrategy implementation.
Put deleteMarkers = new Put(delete.getRow(), delete.getTimeStamp());
for (byte[] family : delete.getFamilyCellMap().keySet()) {
List<Cell> familyCells = delete.getFamilyCellMap().get(family);
if (isFamilyDelete(familyCells)) {
deleteMarkers.add(family, TxConstants.FAMILY_DELETE_QUALIFIER, familyCells.get(0).getTimestamp(),
HConstants.EMPTY_BYTE_ARRAY);
} else {
int cellSize = familyCells.size();
for (Cell cell : familyCells) {
deleteMarkers.add(family, CellUtil.cloneQualifier(cell), cell.getTimestamp(),
HConstants.EMPTY_BYTE_ARRAY);
}
}
}
for (Map.Entry<String, byte[]> entry : delete.getAttributesMap().entrySet()) {
deleteMarkers.setAttribute(entry.getKey(), entry.getValue());
}
e.getEnvironment().getRegion().put(deleteMarkers);
// skip normal delete handling
e.bypass();
}
private boolean isFamilyDelete(List<Cell> familyCells) {
return familyCells.size() == 1 && CellUtil.isDeleteFamily(familyCells.get(0));
}
@Override
public RegionScanner preScannerOpen(ObserverContext<RegionCoprocessorEnvironment> e, Scan scan, RegionScanner s)
throws IOException {
Transaction tx = getFromOperation(scan);
if (tx != null) {
projectFamilyDeletes(scan);
scan.setMaxVersions();
scan.setTimeRange(TxUtils.getOldestVisibleTimestamp(ttlByFamily, tx, readNonTxnData),
TxUtils.getMaxVisibleTimestamp(tx));
Filter newFilter = getTransactionFilter(tx, ScanType.USER_SCAN, scan.getFilter());
scan.setFilter(newFilter);
}
return s;
}
/**
* Ensures that family delete markers are present in the columns requested for any scan operation.
* @param scan The original scan request
* @return The modified scan request with the family delete qualifiers represented
*/
private Scan projectFamilyDeletes(Scan scan) {
for (Map.Entry<byte[], NavigableSet<byte[]>> entry : scan.getFamilyMap().entrySet()) {
NavigableSet<byte[]> columns = entry.getValue();
// wildcard scans will automatically include the delete marker, so only need to add it when we have
// explicit columns listed
if (columns != null && !columns.isEmpty()) {
scan.addColumn(entry.getKey(), TxConstants.FAMILY_DELETE_QUALIFIER);
}
}
return scan;
}
/**
* Ensures that family delete markers are present in the columns requested for any get operation.
* @param get The original get request
* @return The modified get request with the family delete qualifiers represented
*/
private Get projectFamilyDeletes(Get get) {
for (Map.Entry<byte[], NavigableSet<byte[]>> entry : get.getFamilyMap().entrySet()) {
NavigableSet<byte[]> columns = entry.getValue();
// wildcard scans will automatically include the delete marker, so only need to add it when we have
// explicit columns listed
if (columns != null && !columns.isEmpty()) {
get.addColumn(entry.getKey(), TxConstants.FAMILY_DELETE_QUALIFIER);
}
}
return get;
}
@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,
TransactionVisibilityState snapshot, Store store,
List<? extends KeyValueScanner> scanners, ScanType type,
long earliestPutTs) throws IOException {
if (snapshot == null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Region " + env.getRegion().getRegionInfo().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();
// need to see all versions, since we filter out excludes and applications may rely on multiple versions
scan.setMaxVersions();
scan.setFilter(
new IncludeInProgressFilter(dummyTx.getVisibilityUpperBound(),
snapshot.getInvalid(),
getTransactionFilter(dummyTx, type, null)));
return new StoreScanner(store, store.getScanInfo(), scan, scanners,
type, store.getSmallestReadPoint(), earliestPutTs);
}
private Transaction getFromOperation(OperationWithAttributes op) throws IOException {
byte[] encoded = op.getAttribute(TxConstants.TX_OPERATION_ATTRIBUTE_KEY);
if (encoded != null) {
return txCodec.decode(encoded);
}
return null;
}
/**
* 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
* @param type the type of scan being performed
*/
protected Filter getTransactionFilter(Transaction tx, ScanType type, Filter filter) {
return TransactionFilters.getVisibilityFilter(tx, ttlByFamily, allowEmptyValues, type, filter);
}
/**
* 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);
}
}
}