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SnappyData store based off Pivotal GemFireXD
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/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* 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. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.cache.hdfs.internal.hoplog;
import java.io.Closeable;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.EnumMap;
import com.gemstone.gemfire.cache.hdfs.internal.cardinality.ICardinality;
/**
* Ordered sequence file
*/
public interface Hoplog extends Closeable, Comparable {
public static final boolean NOP_WRITE = Boolean.getBoolean("Hoplog.NOP_WRITE");
/** the gemfire magic number for sorted oplogs */
public static final byte[] MAGIC = new byte[] { 0x47, 0x53, 0x4F, 0x50 };
/**
* @return an instance of cached reader, creates one if does not exist
* @throws IOException
*/
HoplogReader getReader() throws IOException;
/**
* Creates a new sorted writer.
*
* @param keys
* an estimate of the number of keys to be written
* @return the writer
* @throws IOException
* error creating writer
*/
HoplogWriter createWriter(int keys) throws IOException;
/**
* @param listener listener of reader's activity
*/
void setReaderActivityListener(HoplogReaderActivityListener listener);
/**
* @return file name
*/
String getFileName();
/**
* @return Entry count estimate for this hoplog
*/
public ICardinality getEntryCountEstimate() throws IOException;
/**
* renames the file to the input name
*
* @throws IOException
*/
void rename(String name) throws IOException;
/**
* Deletes the sorted oplog file
*/
void delete() throws IOException;
/**
* Returns true if the hoplog is closed for reads.
* @return true if closed
*/
boolean isClosed();
/**
* @param clearCache clear this sorted oplog's cache if true
* @throws IOException
*/
void close(boolean clearCache) throws IOException;
/**
* @return the modification timestamp of the file
*/
long getModificationTimeStamp();
/**
* @return the size of file
*/
long getSize();
/**
* Reads sorted oplog file.
*/
public interface HoplogReader extends HoplogSetReader {
/**
* Returns a byte buffer based view of the value linked to the key
*/
ByteBuffer get(byte[] key) throws IOException;
/**
* @return Returns the bloom filter associated with this sorted oplog file.
*/
BloomFilter getBloomFilter() throws IOException;
/**
* @return number of KV pairs in the file, including tombstone entries
*/
long getEntryCount();
/**
* Returns the {@link ICardinality} implementation that is useful for
* estimating the size of this Hoplog.
*
* @return the cardinality estimator
*/
ICardinality getCardinalityEstimator();
}
/**
* Provides hoplog's reader's activity related events to owners
*
* @author ashvina
*/
public interface HoplogReaderActivityListener {
/**
* Invoked when a reader is created and an active reader did not exist
* earlier
*/
public void readerCreated();
/**
* Invoked when an active reader is closed
*/
public void readerClosed();
}
/**
* Writes key/value pairs in a sorted oplog file. Each entry that is appended must have a key that
* is greater than or equal to the previous key.
*/
public interface HoplogWriter extends Closeable {
/**
* Appends another key and value. The key is expected to be greater than or equal to the last
* key that was appended.
* @param key
* @param value
*/
void append(byte[] key, byte[] value) throws IOException;
/**
* Appends another key and value. The key is expected to be greater than or equal to the last
* key that was appended.
*/
void append(byte[] key, int keyOffest, int keyLength, byte[] value, int valueOffset,
int valueLength) throws IOException;
void close(EnumMap metadata) throws IOException;
/**
* flushes all outstanding data into the OS buffers on all DN replicas
* @throws IOException
*/
void hsync() throws IOException;
/**
* Gets the size of the data that has already been written
* to the writer.
*
* @return number of bytes already written to the writer
*/
public long getCurrentSize() throws IOException;
}
/**
* Identifies the gemfire sorted oplog versions.
*/
public enum HoplogVersion {
V1;
/**
* Returns the version string as bytes.
*
* @return the byte form
*/
public byte[] toBytes() {
return name().getBytes();
}
/**
* Constructs the version from a byte array.
*
* @param version
* the byte form of the version
* @return the version enum
*/
public static HoplogVersion fromBytes(byte[] version) {
return HoplogVersion.valueOf(new String(version));
}
}
/**
* Names the available metadata keys that will be stored in the sorted oplog.
*/
public enum Meta {
/** identifies the soplog as a gemfire file, required */
GEMFIRE_MAGIC,
/** identifies the soplog version, required */
SORTED_OPLOG_VERSION,
/** identifies the gemfire version the soplog was created with */
GEMFIRE_VERSION,
/** identifies the statistics data */
STATISTICS,
/** identifies the embedded comparator types */
COMPARATORS,
/** identifies the pdx type data, optional */
PDX,
/**
* identifies the hyperLogLog byte[] which estimates the cardinality for
* only one hoplog
*/
LOCAL_CARDINALITY_ESTIMATE,
/**
* represents the hyperLogLog byte[] after upgrading the constant from
* 0.1 to 0.03 (in gfxd 1.4)
*/
LOCAL_CARDINALITY_ESTIMATE_V2
;
/**
* Converts the metadata name to bytes.
*/
public byte[] toBytes() {
return ("gemfire." + name()).getBytes();
}
/**
* Converts the byte form of the name to an enum.
*
* @param key
* the key as bytes
* @return the enum form
*/
public static Meta fromBytes(byte[] key) {
return Meta.valueOf(new String(key).substring("gemfire.".length()));
}
}
}