com.continuuity.tephra.hbase94.coprocessor.TransactionProcessor Maven / Gradle / Ivy

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/*
 * 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.hbase94.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.hbase94.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.CoprocessorEnvironment;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
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.DataInput;
import java.io.DataOutput;
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:
 * 
 *   applies filtering to exclude data from invalid and in-progress transactions
 *   overrides the scanner returned for flush and compaction to drop data written by invalidated transactions,
 *   or expired due to TTL.
 * 
 *
 * 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
 * 
 *   hbase.coprocessor.region.classes
 *   com.continuuity.tephra.hbase94.coprocessor.TransactionProcessor
 * 
 * }
 * 
 *
 * 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);
 * }
 * 
 */
public class TransactionProcessor extends BaseRegionObserver {
  private static final Log LOG = LogFactory.getLog(TransactionProcessor.class);

  private TransactionStateCache cache;
  private final TransactionCodec txCodec;
  protected Map 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 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 getTransactionStateCacheSupplier(RegionCoprocessorEnvironment env) {
    return new TransactionStateCacheSupplier(env.getConfiguration());
  }

  @Override
  public void stop(CoprocessorEnvironment e) throws IOException {
    // nothing to do
  }

  @Override
  public void preGet(ObserverContext e, Get get, List results)
    throws IOException {
    Transaction tx = txCodec.getFromOperation(get);
    if (tx != null) {
      if (LOG.isTraceEnabled()) {
        LOG.trace("Applying filter to GET for transaction " + tx.getWritePointer());
      }
      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 e, Scan scan, RegionScanner s)
    throws IOException {
    Transaction tx = txCodec.getFromOperation(scan);
    if (tx != null) {
      if (LOG.isTraceEnabled()) {
        LOG.trace("Applying filter to SCAN for transaction " + tx.getWritePointer());
      }
      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 c, Store store,
                                             KeyValueScanner memstoreScanner, InternalScanner s)
      throws IOException {
    return createStoreScanner(c.getEnvironment(), "flush", cache.getLatestState(), store,
                              Collections.singletonList(memstoreScanner), ScanType.MINOR_COMPACT,
                              HConstants.OLDEST_TIMESTAMP);
  }

  @Override
  public InternalScanner preCompactScannerOpen(ObserverContext c, Store store,
      List 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 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,
                            env.getRegion().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 invalidIds;
    private final Filter txFilter;

    public IncludeInProgressFilter(long upperBound, Collection invalids, Filter transactionFilter) {
      this.visibilityUpperBound = upperBound;
      this.invalidIds = Sets.newHashSet(invalids);
      this.txFilter = transactionFilter;
    }

    @Override
    public ReturnCode filterKeyValue(KeyValue cell) {
      // 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);
    }

    @Override
    public void write(DataOutput dataOutput) throws IOException {
      throw new UnsupportedOperationException("IncludeInProgressFilter only intended for server-side use.");
    }

    @Override
    public void readFields(DataInput dataInput) throws IOException {
      throw new UnsupportedOperationException("IncludeInProgressFilter only intended for server-side use.");
    }
  }
}