distributedlog-protocol/src/main/java/com/twitter/distributedlog/DLSN.java - distributedlog - Git at Google

 /**
  * 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 com.twitter.distributedlog;

 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import org.apache.commons.codec.binary.Base64;
 import org.apache.commons.codec.binary.Hex;

 import java.nio.ByteBuffer;

 /**
  * DistributedLog Sequence Number (DLSN) is the system generated sequence number for log record.
  *
  * <p>DLSN is comprised with 3 components:
  * <ul>
  * <li>LogSegment Sequence Number: the sequence number of log segment that the record is written in
  * <li>Entry Id: the entry id of the entry that the record is batched in
  * <li>Slot Id: the slot id that the record is in the entry
  * </ul>
  *
  * @see LogRecordWithDLSN
  */
 public class DLSN implements Comparable<DLSN> {

     public static final byte VERSION0 = (byte) 0;
     public static final byte VERSION1 = (byte) 1;

     // The initial DLSN that DL starts with
     public static final DLSN InitialDLSN = new DLSN(1, 0 , 0);
     // The non-inclusive lower bound DLSN
     public static final DLSN NonInclusiveLowerBound = new DLSN(1, 0 , -1);
     // Invalid DLSN
     public static final DLSN InvalidDLSN = new DLSN(0,-1,-1);

     static final byte CUR_VERSION = VERSION1;
     static final int VERSION0_LEN = Long.SIZE * 3 + Byte.SIZE;
     static final int VERSION1_LEN = Long.SIZE * 3 / Byte.SIZE + 1;

     private final long logSegmentSequenceNo;
     private final long entryId;
     private final long slotId;

     public DLSN(long logSegmentSequenceNo, long entryId, long slotId) {
         this.logSegmentSequenceNo = logSegmentSequenceNo;
         this.entryId = entryId;
         this.slotId = slotId;
     }

     /**
      * Return the sequence number of the log segment that the record is written to.
      *
      * @return sequence number of the log segment that the record is written to.
      */
     public long getLogSegmentSequenceNo() {
         return logSegmentSequenceNo;
     }

     /**
      * use {@link #getLogSegmentSequenceNo()} instead
      */
     @Deprecated
     long getLedgerSequenceNo() {
         return logSegmentSequenceNo;
     }

     /**
      * Return the entry id of the batch that the record is written to.
      *
      * @return entry id of the batch that the record is written to.
      */
     public long getEntryId() {
         return entryId;
     }

     /**
      * Return the slot id in the batch that the record is written to.
      *
      * @return slot id in the batch that the record is written to.
      */
     public long getSlotId() {
         return slotId;
     }

     @Override
     public int compareTo(DLSN that) {
         if (this.logSegmentSequenceNo != that.logSegmentSequenceNo) {
             return (this.logSegmentSequenceNo < that.logSegmentSequenceNo)? -1 : 1;
         } else if (this.entryId != that.entryId) {
             return (this.entryId < that.entryId)? -1 : 1;
         } else {
             return (this.slotId < that.slotId)? -1 : (this.slotId == that.slotId)? 0 : 1;
         }
     }

     /**
      * Serialize the DLSN into bytes with current version.
      *
      * @return the serialized bytes
      */
     public byte[] serializeBytes() {
         return serializeBytes(CUR_VERSION);
     }

     /**
      * Serialize the DLSN into bytes with given <code>version</code>.
      *
      * @param version
      *          version to serialize the DLSN
      * @return the serialized bytes
      */
     public byte[] serializeBytes(byte version) {
         Preconditions.checkArgument(version <= CUR_VERSION && version >= VERSION0);
         byte[] data = new byte[CUR_VERSION == version ? VERSION1_LEN : VERSION0_LEN];
         ByteBuffer bb = ByteBuffer.wrap(data);
         bb.put(version);
         bb.putLong(logSegmentSequenceNo);
         bb.putLong(entryId);
         bb.putLong(slotId);
         return data;
     }

     /**
      * Serialize the DLSN into base64 encoded string.
      *
      * @return serialized base64 string
      * @see #serializeBytes()
      */
     public String serialize() {
         return serialize(CUR_VERSION);
     }

     /**
      * Serialize the DLSN into base64 encoded string with given <code>version</code>.
      *
      * @param version
      *          version to serialize the DLSN
      * @return the serialized base64 string
      * @see #serializeBytes(byte)
      */
     public String serialize(byte version) {
         return Base64.encodeBase64String(serializeBytes(version));
     }

     /**
      * Deserialize the DLSN from base64 encoded string <code>dlsn</code>.
      *
      * @param dlsn
      *          base64 encoded string
      * @return dlsn
      */
     public static DLSN deserialize(String dlsn) {
         byte[] data = Base64.decodeBase64(dlsn);
         return deserializeBytes(data);
     }

     /**
      * Deserialize the DLSN from bytes array.
      *
      * @param data
      *          serialized bytes
      * @return dlsn
      */
     public static DLSN deserializeBytes(byte[] data) {
         ByteBuffer bb = ByteBuffer.wrap(data);
         byte version = bb.get();
         if (VERSION0 == version) {
             if (VERSION0_LEN != data.length) {
                 throw new IllegalArgumentException("Invalid version zero DLSN " + Hex.encodeHexString(data));
             }
         } else if (VERSION1 == version) {
             if (VERSION1_LEN != data.length) {
                 throw new IllegalArgumentException("Invalid version one DLSN " + Hex.encodeHexString(data));
             }
         } else {
             throw new IllegalArgumentException("Invalid DLSN : version = "
                     + version + ", " + Hex.encodeHexString(data));
         }
         return new DLSN(bb.getLong(), bb.getLong(), bb.getLong());
     }

     // Keep original version0 logic for testing.
     @VisibleForTesting
     static DLSN deserialize0(String dlsn) {
         byte[] data = Base64.decodeBase64(dlsn);
         ByteBuffer bb = ByteBuffer.wrap(data);
         byte version = bb.get();
         if (VERSION0 != version || VERSION0_LEN != data.length) {
             throw new IllegalArgumentException("Invalid DLSN " + dlsn);
         }
         return new DLSN(bb.getLong(), bb.getLong(), bb.getLong());
     }

     @Override
     public String toString() {
         return "DLSN{" +
             "logSegmentSequenceNo=" + logSegmentSequenceNo +
             ", entryId=" + entryId +
             ", slotId=" + slotId +
             '}';
     }

     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (!(o instanceof DLSN)) return false;

         DLSN dlsn = (DLSN) o;

         if (entryId != dlsn.entryId) return false;
         if (logSegmentSequenceNo != dlsn.logSegmentSequenceNo) return false;
         if (slotId != dlsn.slotId) return false;

         return true;
     }

     @Override
     public int hashCode() {
         int result = (int) (logSegmentSequenceNo ^ (logSegmentSequenceNo >>> 32));
         result = 31 * result + (int) (entryId ^ (entryId >>> 32));
         result = 31 * result + (int) (slotId ^ (slotId >>> 32));
         return result;
     }

     /**
      * Positions to a DLSN greater than the current value - this may not
      * correspond to an actual LogRecord, its just used by the positioning logic
      * to position the reader
      *
      * @return the next DLSN
      */
     public DLSN getNextDLSN() {
         return new DLSN(logSegmentSequenceNo, entryId, slotId + 1);
     }

     /**
      * Positions to a DLSN greater than the current value - this may not
      * correspond to an actual LogRecord, its just used by the positioning logic
      * to position the reader
      *
      * @return the next DLSN
      */
     public DLSN positionOnTheNextLedger() {
         return new DLSN(logSegmentSequenceNo + 1 , 0, 0);
     }
 }
	/**
	* 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 com.twitter.distributedlog;

	import com.google.common.annotations.VisibleForTesting;
	import com.google.common.base.Preconditions;
	import org.apache.commons.codec.binary.Base64;
	import org.apache.commons.codec.binary.Hex;

	import java.nio.ByteBuffer;

	/**
	* DistributedLog Sequence Number (DLSN) is the system generated sequence number for log record.
	*
	* <p>DLSN is comprised with 3 components:
	* <ul>
	* <li>LogSegment Sequence Number: the sequence number of log segment that the record is written in
	* <li>Entry Id: the entry id of the entry that the record is batched in
	* <li>Slot Id: the slot id that the record is in the entry
	* </ul>
	*
	* @see LogRecordWithDLSN
	*/
	public class DLSN implements Comparable<DLSN> {

	public static final byte VERSION0 = (byte) 0;
	public static final byte VERSION1 = (byte) 1;

	// The initial DLSN that DL starts with
	public static final DLSN InitialDLSN = new DLSN(1, 0 , 0);
	// The non-inclusive lower bound DLSN
	public static final DLSN NonInclusiveLowerBound = new DLSN(1, 0 , -1);
	// Invalid DLSN
	public static final DLSN InvalidDLSN = new DLSN(0,-1,-1);

	static final byte CUR_VERSION = VERSION1;
	static final int VERSION0_LEN = Long.SIZE * 3 + Byte.SIZE;
	static final int VERSION1_LEN = Long.SIZE * 3 / Byte.SIZE + 1;

	private final long logSegmentSequenceNo;
	private final long entryId;
	private final long slotId;

	public DLSN(long logSegmentSequenceNo, long entryId, long slotId) {
	this.logSegmentSequenceNo = logSegmentSequenceNo;
	this.entryId = entryId;
	this.slotId = slotId;
	}

	/**
	* Return the sequence number of the log segment that the record is written to.
	*
	* @return sequence number of the log segment that the record is written to.
	*/
	public long getLogSegmentSequenceNo() {
	return logSegmentSequenceNo;
	}

	/**
	* use {@link #getLogSegmentSequenceNo()} instead
	*/
	@Deprecated
	long getLedgerSequenceNo() {
	return logSegmentSequenceNo;
	}

	/**
	* Return the entry id of the batch that the record is written to.
	*
	* @return entry id of the batch that the record is written to.
	*/
	public long getEntryId() {
	return entryId;
	}

	/**
	* Return the slot id in the batch that the record is written to.
	*
	* @return slot id in the batch that the record is written to.
	*/
	public long getSlotId() {
	return slotId;
	}

	@Override
	public int compareTo(DLSN that) {
	if (this.logSegmentSequenceNo != that.logSegmentSequenceNo) {
	return (this.logSegmentSequenceNo < that.logSegmentSequenceNo)? -1 : 1;
	} else if (this.entryId != that.entryId) {
	return (this.entryId < that.entryId)? -1 : 1;
	} else {
	return (this.slotId < that.slotId)? -1 : (this.slotId == that.slotId)? 0 : 1;
	}
	}

	/**
	* Serialize the DLSN into bytes with current version.
	*
	* @return the serialized bytes
	*/
	public byte[] serializeBytes() {
	return serializeBytes(CUR_VERSION);
	}

	/**
	* Serialize the DLSN into bytes with given <code>version</code>.
	*
	* @param version
	* version to serialize the DLSN
	* @return the serialized bytes
	*/
	public byte[] serializeBytes(byte version) {
	Preconditions.checkArgument(version <= CUR_VERSION && version >= VERSION0);
	byte[] data = new byte[CUR_VERSION == version ? VERSION1_LEN : VERSION0_LEN];
	ByteBuffer bb = ByteBuffer.wrap(data);
	bb.put(version);
	bb.putLong(logSegmentSequenceNo);
	bb.putLong(entryId);
	bb.putLong(slotId);
	return data;
	}

	/**
	* Serialize the DLSN into base64 encoded string.
	*
	* @return serialized base64 string
	* @see #serializeBytes()
	*/
	public String serialize() {
	return serialize(CUR_VERSION);
	}

	/**
	* Serialize the DLSN into base64 encoded string with given <code>version</code>.
	*
	* @param version
	* version to serialize the DLSN
	* @return the serialized base64 string
	* @see #serializeBytes(byte)
	*/
	public String serialize(byte version) {
	return Base64.encodeBase64String(serializeBytes(version));
	}

	/**
	* Deserialize the DLSN from base64 encoded string <code>dlsn</code>.
	*
	* @param dlsn
	* base64 encoded string
	* @return dlsn
	*/
	public static DLSN deserialize(String dlsn) {
	byte[] data = Base64.decodeBase64(dlsn);
	return deserializeBytes(data);
	}

	/**
	* Deserialize the DLSN from bytes array.
	*
	* @param data
	* serialized bytes
	* @return dlsn
	*/
	public static DLSN deserializeBytes(byte[] data) {
	ByteBuffer bb = ByteBuffer.wrap(data);
	byte version = bb.get();
	if (VERSION0 == version) {
	if (VERSION0_LEN != data.length) {
	throw new IllegalArgumentException("Invalid version zero DLSN " + Hex.encodeHexString(data));
	}
	} else if (VERSION1 == version) {
	if (VERSION1_LEN != data.length) {
	throw new IllegalArgumentException("Invalid version one DLSN " + Hex.encodeHexString(data));
	}
	} else {
	throw new IllegalArgumentException("Invalid DLSN : version = "
	+ version + ", " + Hex.encodeHexString(data));
	}
	return new DLSN(bb.getLong(), bb.getLong(), bb.getLong());
	}

	// Keep original version0 logic for testing.
	@VisibleForTesting
	static DLSN deserialize0(String dlsn) {
	byte[] data = Base64.decodeBase64(dlsn);
	ByteBuffer bb = ByteBuffer.wrap(data);
	byte version = bb.get();
	if (VERSION0 != version \|\| VERSION0_LEN != data.length) {
	throw new IllegalArgumentException("Invalid DLSN " + dlsn);
	}
	return new DLSN(bb.getLong(), bb.getLong(), bb.getLong());
	}

	@Override
	public String toString() {
	return "DLSN{" +
	"logSegmentSequenceNo=" + logSegmentSequenceNo +
	", entryId=" + entryId +
	", slotId=" + slotId +
	'}';
	}

	@Override
	public boolean equals(Object o) {
	if (this == o) return true;
	if (!(o instanceof DLSN)) return false;

	DLSN dlsn = (DLSN) o;

	if (entryId != dlsn.entryId) return false;
	if (logSegmentSequenceNo != dlsn.logSegmentSequenceNo) return false;
	if (slotId != dlsn.slotId) return false;

	return true;
	}

	@Override
	public int hashCode() {
	int result = (int) (logSegmentSequenceNo ^ (logSegmentSequenceNo >>> 32));
	result = 31 * result + (int) (entryId ^ (entryId >>> 32));
	result = 31 * result + (int) (slotId ^ (slotId >>> 32));
	return result;
	}

	/**
	* Positions to a DLSN greater than the current value - this may not
	* correspond to an actual LogRecord, its just used by the positioning logic
	* to position the reader
	*
	* @return the next DLSN
	*/
	public DLSN getNextDLSN() {
	return new DLSN(logSegmentSequenceNo, entryId, slotId + 1);
	}

	/**
	* Positions to a DLSN greater than the current value - this may not
	* correspond to an actual LogRecord, its just used by the positioning logic
	* to position the reader
	*
	* @return the next DLSN
	*/
	public DLSN positionOnTheNextLedger() {
	return new DLSN(logSegmentSequenceNo + 1 , 0, 0);
	}
	}