modules/core/src/main/java/org/apache/fluo/core/log/TracingCellScanner.java

/*
 * 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.fluo.core.log;

import java.util.Iterator;

import com.google.common.collect.Iterators;
import org.apache.fluo.api.client.scanner.CellScanner;
import org.apache.fluo.api.config.FluoConfiguration;
import org.apache.fluo.api.data.RowColumnValue;
import org.apache.fluo.core.util.Hex;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TracingCellScanner implements CellScanner {
  static final Logger log = LoggerFactory.getLogger(FluoConfiguration.TRANSACTION_PREFIX + ".scan");

  private final CellScanner wrappedScanner;
  private final long txid;
  private final String scanId;

  TracingCellScanner(CellScanner wrappedScanner, long txid, String scanId) {
    this.wrappedScanner = wrappedScanner;
    this.txid = txid;
    this.scanId = scanId;
  }

  @Override
  public Iterator<RowColumnValue> iterator() {
    return Iterators.transform(
        wrappedScanner.iterator(),
        rcv -> {
          log.trace("txid: {} scanId: {} next()-> {} {}", txid, scanId,
              Hex.encNonAscii(rcv.getRowColumn()), Hex.encNonAscii(rcv.getValue()));
          return rcv;
        });
  }
}