gemfire-core/src/main/java/com/gemstone/gemfire/internal/redis/executor/string/AppendExecutor.java

package com.gemstone.gemfire.internal.redis.executor.string;

import java.util.List;

import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.internal.redis.ByteArrayWrapper;
import com.gemstone.gemfire.internal.redis.Command;
import com.gemstone.gemfire.internal.redis.Coder;
import com.gemstone.gemfire.internal.redis.ExecutionHandlerContext;
import com.gemstone.gemfire.internal.redis.RedisConstants.ArityDef;

public class AppendExecutor extends StringExecutor {
  
  private final int VALUE_INDEX = 2;
  
  @Override
  public void executeCommand(Command command, ExecutionHandlerContext context) {
    List<byte[]> commandElems = command.getProcessedCommand();

    Region<ByteArrayWrapper, ByteArrayWrapper> r = context.getRegionCache().getStringsRegion();;

    if (commandElems.size() < 3) {
      command.setResponse(Coder.getErrorResponse(context.getByteBufAllocator(), ArityDef.APPEND));
      return;
    }

    ByteArrayWrapper key = command.getKey();
    checkAndSetDataType(key, context);
    ByteArrayWrapper string = r.get(key);

    byte[] stringByteArray = commandElems.get(VALUE_INDEX);
    if (string == null) {
      r.put(key, new ByteArrayWrapper(stringByteArray));
      command.setResponse(Coder.getIntegerResponse(context.getByteBufAllocator(), stringByteArray.length));
    } else {
      byte[] newValue = concatArrays(string.toBytes(), stringByteArray);
      string.setBytes(newValue);
      r.put(key, string);
      command.setResponse(Coder.getIntegerResponse(context.getByteBufAllocator(), newValue.length));
    }

  }

  private byte[] concatArrays(byte[] o, byte[] n) {
    int oLen = o.length;
    int nLen = n.length;
    byte[] combined = new byte[oLen+nLen];
    System.arraycopy(o, 0, combined, 0, oLen);
    System.arraycopy(n, 0, combined, oLen, nLen);
    return combined;
  }

}