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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.utils.obs;
import java.io.*;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.io.util.Memory;
import org.apache.cassandra.io.util.MemoryOutputStream;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.concurrent.Ref;
/**
* Off-heap bitset,
* file compatible with OpeBitSet
*/
public class OffHeapBitSet implements IBitSet
{
private final Memory bytes;
public OffHeapBitSet(long numBits)
{
/** returns the number of 64 bit words it would take to hold numBits */
long wordCount = (((numBits - 1) >>> 6) + 1);
if (wordCount > Integer.MAX_VALUE)
throw new UnsupportedOperationException("Bloom filter size is > 16GB, reduce the bloom_filter_fp_chance");
try
{
long byteCount = wordCount * 8L;
bytes = Memory.allocate(byteCount);
}
catch (OutOfMemoryError e)
{
throw new RuntimeException("Out of native memory occured, You can avoid it by increasing the system ram space or by increasing bloom_filter_fp_chance.");
}
// flush/clear the existing memory.
clear();
}
private OffHeapBitSet(Memory bytes)
{
this.bytes = bytes;
}
public long capacity()
{
return bytes.size() * 8;
}
@Override
public long offHeapSize()
{
return bytes.size();
}
public void addTo(Ref.IdentityCollection identities)
{
identities.add(bytes);
}
public boolean get(long index)
{
long i = index >> 3;
long bit = index & 0x7;
int bitmask = 0x1 << bit;
return (bytes.getByte(i) & bitmask) != 0;
}
public void set(long index)
{
long i = index >> 3;
long bit = index & 0x7;
int bitmask = 0x1 << bit;
bytes.setByte(i, (byte) (bitmask | bytes.getByte(i)));
}
public void set(long offset, byte b)
{
bytes.setByte(offset, b);
}
public void clear(long index)
{
long i = index >> 3;
long bit = index & 0x7;
int bitmask = 0x1 << bit;
int nativeByte = (bytes.getByte(i) & 0xFF);
nativeByte &= ~bitmask;
bytes.setByte(i, (byte) nativeByte);
}
public void clear()
{
bytes.setMemory(0, bytes.size(), (byte) 0);
}
public void serialize(DataOutputPlus out) throws IOException
{
out.writeInt((int) (bytes.size() / 8));
out.write(bytes, 0, bytes.size());
}
@VisibleForTesting
public void serializeOldBfFormat(DataOutputPlus out) throws IOException
{
out.writeInt((int) (bytes.size() / 8));
for (long i = 0; i < bytes.size(); )
{
long value = ((bytes.getByte(i++) & 0xff) << 0)
+ ((bytes.getByte(i++) & 0xff) << 8)
+ ((bytes.getByte(i++) & 0xff) << 16)
+ ((long) (bytes.getByte(i++) & 0xff) << 24)
+ ((long) (bytes.getByte(i++) & 0xff) << 32)
+ ((long) (bytes.getByte(i++) & 0xff) << 40)
+ ((long) (bytes.getByte(i++) & 0xff) << 48)
+ ((long) bytes.getByte(i++) << 56);
out.writeLong(value);
}
}
public long serializedSize()
{
return TypeSizes.sizeof((int) bytes.size()) + bytes.size();
}
public static OffHeapBitSet deserialize(I in, boolean oldBfFormat) throws IOException
{
long byteCount = in.readInt() * 8L;
Memory memory = Memory.allocate(byteCount);
if (oldBfFormat)
{
for (long i = 0; i < byteCount; )
{
long v = in.readLong();
memory.setByte(i++, (byte) (v >>> 0));
memory.setByte(i++, (byte) (v >>> 8));
memory.setByte(i++, (byte) (v >>> 16));
memory.setByte(i++, (byte) (v >>> 24));
memory.setByte(i++, (byte) (v >>> 32));
memory.setByte(i++, (byte) (v >>> 40));
memory.setByte(i++, (byte) (v >>> 48));
memory.setByte(i++, (byte) (v >>> 56));
}
}
else
{
FBUtilities.copy(in, new MemoryOutputStream(memory), byteCount);
}
return new OffHeapBitSet(memory);
}
public void close()
{
bytes.free();
}
@Override
public boolean equals(Object o)
{
if (this == o)
return true;
if (!(o instanceof OffHeapBitSet))
return false;
OffHeapBitSet b = (OffHeapBitSet) o;
return bytes.equals(b.bytes);
}
@Override
public int hashCode()
{
// Similar to open bitset.
long h = 0;
for (long i = bytes.size(); --i >= 0;)
{
h ^= bytes.getByte(i);
h = (h << 1) | (h >>> 63); // rotate left
}
return (int) ((h >> 32) ^ h) + 0x98761234;
}
public String toString()
{
return "[OffHeapBitSet]";
}
}