import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
@SuppressWarnings("deprecation")
private static ImmutableSet<FSEditLogOpCodes> skippedOps() {
  ImmutableSet.Builder<FSEditLogOpCodes> b = ImmutableSet.builder();

  // Deprecated opcodes
  b.add(FSEditLogOpCodes.OP_DATANODE_ADD)
      .add(FSEditLogOpCodes.OP_DATANODE_REMOVE)
      .add(FSEditLogOpCodes.OP_SET_NS_QUOTA)
      .add(FSEditLogOpCodes.OP_CLEAR_NS_QUOTA)
      .add(FSEditLogOpCodes.OP_SET_GENSTAMP_V1);

  // Cannot test delegation token related code in insecure set up
  b.add(FSEditLogOpCodes.OP_GET_DELEGATION_TOKEN)
      .add(FSEditLogOpCodes.OP_RENEW_DELEGATION_TOKEN)
      .add(FSEditLogOpCodes.OP_CANCEL_DELEGATION_TOKEN);

  // Skip invalid opcode
  b.add(FSEditLogOpCodes.OP_INVALID);
  return b.build();
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
@SuppressWarnings("deprecation")
private static ImmutableSet<FSEditLogOpCodes> skippedOps() {
  ImmutableSet.Builder<FSEditLogOpCodes> b = ImmutableSet
      .<FSEditLogOpCodes> builder();

  // Deprecated opcodes
  b.add(FSEditLogOpCodes.OP_DATANODE_ADD)
      .add(FSEditLogOpCodes.OP_DATANODE_REMOVE)
      .add(FSEditLogOpCodes.OP_SET_NS_QUOTA)
      .add(FSEditLogOpCodes.OP_CLEAR_NS_QUOTA)
      .add(FSEditLogOpCodes.OP_SET_GENSTAMP_V1);

  // Cannot test delegation token related code in insecure set up
  b.add(FSEditLogOpCodes.OP_GET_DELEGATION_TOKEN)
      .add(FSEditLogOpCodes.OP_RENEW_DELEGATION_TOKEN)
      .add(FSEditLogOpCodes.OP_CANCEL_DELEGATION_TOKEN);

  // Skip invalid opcode
  b.add(FSEditLogOpCodes.OP_INVALID);
  return b.build();
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * Increment the op code counter
 *
 * @param opCode opCode for which to increment count
 */
private void incrementOpCodeCount(FSEditLogOpCodes opCode) {
  if(!opCodeCount.containsKey(opCode)) {
    opCodeCount.put(opCode, 0L);
  }
  Long newValue = opCodeCount.get(opCode) + 1;
  opCodeCount.put(opCode, newValue);
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * Get the statistics in string format, suitable for printing
 *
 * @return statistics in in string format, suitable for printing
 */
public String getStatisticsString() {
  StringBuffer sb = new StringBuffer();
  sb.append(String.format(
      "    %-30.30s      : %d%n",
      "VERSION", version));
  for(FSEditLogOpCodes opCode : FSEditLogOpCodes.values()) {
    sb.append(String.format(
      "    %-30.30s (%3d): %d%n",
      opCode.toString(),
      opCode.getOpCode(),
      opCodeCount.get(opCode)));
  }
  return sb.toString();
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * Verify that the given list of streams contains exactly the range of
 * transactions specified, inclusive.
 */
public static void verifyEdits(List<EditLogInputStream> streams,
    int firstTxnId, int lastTxnId) throws IOException {
  
  Iterator<EditLogInputStream> iter = streams.iterator();
  assertTrue(iter.hasNext());
  EditLogInputStream stream = iter.next();
  
  for (int expected = firstTxnId;
      expected <= lastTxnId;
      expected++) {
    
    FSEditLogOp op = stream.readOp();
    while (op == null) {
      assertTrue("Expected to find txid " + expected + ", " +
          "but no more streams available to read from",
          iter.hasNext());
      stream = iter.next();
      op = stream.readOp();
    }
    
    assertEquals(FSEditLogOpCodes.OP_MKDIR, op.opCode);
    assertEquals(expected, op.getTransactionId());
  }
  
  assertNull(stream.readOp());
  assertFalse("Expected no more txns after " + lastTxnId +
      " but more streams are available", iter.hasNext());
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * Compare two files, ignore trailing zeros at the end, for edits log the
 * trailing zeros do not make any difference, throw exception is the files are
 * not same
 *
 * @param filenameSmall first file to compare (doesn't have to be smaller)
 * @param filenameLarge second file to compare (doesn't have to be larger)
 */
private boolean filesEqualIgnoreTrailingZeros(String filenameSmall,
  String filenameLarge) throws IOException {

  ByteBuffer small = ByteBuffer.wrap(DFSTestUtil.loadFile(filenameSmall));
  ByteBuffer large = ByteBuffer.wrap(DFSTestUtil.loadFile(filenameLarge));

  // now correct if it's otherwise
  if (small.capacity() > large.capacity()) {
    ByteBuffer tmpByteBuffer = small;
    small = large;
    large = tmpByteBuffer;
    String tmpFilename = filenameSmall;
    filenameSmall = filenameLarge;
    filenameLarge = tmpFilename;
  }

  // compare from 0 to capacity of small
  // the rest of the large should be all zeros
  small.position(0);
  small.limit(small.capacity());
  large.position(0);
  large.limit(small.capacity());

  // compares position to limit
  if (!small.equals(large)) {
    return false;
  }

  // everything after limit should be 0xFF
  int i = large.limit();
  large.clear();
  for (; i < large.capacity(); i++) {
    if (large.get(i) != FSEditLogOpCodes.OP_INVALID.getOpCode()) {
      return false;
    }
  }

  return true;
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * Compare two files, ignore trailing zeros at the end,
 * for edits log the trailing zeros do not make any difference,
 * throw exception is the files are not same
 *
 * @param filenameSmall first file to compare (doesn't have to be smaller)
 * @param filenameLarge second file to compare (doesn't have to be larger)
 */
private boolean filesEqualIgnoreTrailingZeros(String filenameSmall,
  String filenameLarge) throws IOException {

  ByteBuffer small = ByteBuffer.wrap(DFSTestUtil.loadFile(filenameSmall));
  ByteBuffer large = ByteBuffer.wrap(DFSTestUtil.loadFile(filenameLarge));

  // now correct if it's otherwise
  if(small.capacity() > large.capacity()) {
    ByteBuffer tmpByteBuffer = small;
    small = large;
    large = tmpByteBuffer;
    String tmpFilename = filenameSmall;
    filenameSmall = filenameLarge;
    filenameLarge = tmpFilename;
  }

  // compare from 0 to capacity of small
  // the rest of the large should be all zeros
  small.position(0);
  small.limit(small.capacity());
  large.position(0);
  large.limit(small.capacity());

  // compares position to limit
  if(!small.equals(large)) { return false; }

  // everything after limit should be 0xFF
  int i = large.limit();
  large.clear();
  for(; i < large.capacity(); i++) {
    if(large.get(i) != FSEditLogOpCodes.OP_INVALID.getOpCode()) {
      return false;
    }
  }

  return true;
}
 

import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes; //导入依赖的package包/类
/**
 * For each operation read from the stream, check if this is a closing
 * transaction. If so, we are sure we need to move to the next segment.
 * 
 * We also mark that this is the most recent time, we read something valid
 * from the input.
 */
private void updateState(FSEditLogOp op, boolean checkTxnId) throws IOException {
  InjectionHandler.processEvent(InjectionEvent.SERVERLOGREADER_UPDATE, op);
  
  if (checkTxnId) {
    mostRecentlyReadTransactionTxId = ServerLogReaderUtil.checkTransactionId(
      mostRecentlyReadTransactionTxId, op);
  }
  
  updateStreamPosition();

  // read a valid operation
  core.getMetrics().readOperations.inc();
  mostRecentlyReadTransactionTime = now();

  // current log segment ends normally
  if (op.opCode == FSEditLogOpCodes.OP_END_LOG_SEGMENT) {
    LOG.info("Segment - ending log segment start txid: " + currentSegmentTxId
        + ", end txid: " + op.getTransactionId());
    // move forward with next segment
    currentSegmentTxId = op.getTransactionId() + 1;
    // set the stream to null so the next getNotification()
    // will recreate it
    currentEditLogInputStream = null;
    // indicate that a new stream will be opened
    currentEditLogInputStreamPosition = -1;
  } else if (op.opCode == FSEditLogOpCodes.OP_START_LOG_SEGMENT) {
    LOG.info("Segment - starting log segment start txid: "
        + currentSegmentTxId);
  }
}