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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.datastax.oss.driver.internal.core.metadata.token;
import com.datastax.oss.driver.api.core.metadata.token.Token;
import com.datastax.oss.driver.api.core.metadata.token.TokenRange;
import com.datastax.oss.driver.shaded.guava.common.collect.Lists;
import com.datastax.oss.protocol.internal.util.Bytes;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.List;
import net.jcip.annotations.Immutable;
@Immutable
public class ByteOrderedTokenRange extends TokenRangeBase {
private static final BigInteger TWO = BigInteger.valueOf(2);
public ByteOrderedTokenRange(ByteOrderedToken start, ByteOrderedToken end) {
super(start, end, ByteOrderedTokenFactory.MIN_TOKEN);
}
@Override
protected TokenRange newTokenRange(Token start, Token end) {
return new ByteOrderedTokenRange(((ByteOrderedToken) start), ((ByteOrderedToken) end));
}
@Override
protected List split(Token rawStartToken, Token rawEndToken, int numberOfSplits) {
int tokenOrder = rawStartToken.compareTo(rawEndToken);
// ]min,min] means the whole ring. However, since there is no "max token" with this partitioner,
// we can't come up with a magic end value that would cover the whole ring
if (tokenOrder == 0 && rawStartToken.equals(ByteOrderedTokenFactory.MIN_TOKEN)) {
throw new IllegalArgumentException("Cannot split whole ring with ordered partitioner");
}
ByteOrderedToken startToken = (ByteOrderedToken) rawStartToken;
ByteOrderedToken endToken = (ByteOrderedToken) rawEndToken;
int significantBytes;
BigInteger start, end, range, ringEnd, ringLength;
BigInteger bigNumberOfSplits = BigInteger.valueOf(numberOfSplits);
if (tokenOrder < 0) {
// Since tokens are compared lexicographically, convert to integers using the largest length
// (ex: given 0x0A and 0x0BCD, switch to 0x0A00 and 0x0BCD)
significantBytes = Math.max(startToken.getValue().capacity(), endToken.getValue().capacity());
// If the number of splits does not fit in the difference between the two integers, use more
// bytes (ex: cannot fit 4 splits between 0x01 and 0x03, so switch to 0x0100 and 0x0300)
// At most 4 additional bytes will be needed, since numberOfSplits is an integer.
int addedBytes = 0;
while (true) {
start = toBigInteger(startToken.getValue(), significantBytes);
end = toBigInteger(endToken.getValue(), significantBytes);
range = end.subtract(start);
if (addedBytes == 4 || start.equals(end) || range.compareTo(bigNumberOfSplits) >= 0) {
break;
}
significantBytes += 1;
addedBytes += 1;
}
ringEnd = ringLength = null; // won't be used
} else {
// Same logic except that we wrap around the ring
significantBytes = Math.max(startToken.getValue().capacity(), endToken.getValue().capacity());
int addedBytes = 0;
while (true) {
start = toBigInteger(startToken.getValue(), significantBytes);
end = toBigInteger(endToken.getValue(), significantBytes);
ringLength = TWO.pow(significantBytes * 8);
ringEnd = ringLength.subtract(BigInteger.ONE);
range = end.subtract(start).add(ringLength);
if (addedBytes == 4 || range.compareTo(bigNumberOfSplits) >= 0) {
break;
}
significantBytes += 1;
addedBytes += 1;
}
}
List values = super.split(start, range, ringEnd, ringLength, numberOfSplits);
List tokens = Lists.newArrayListWithExpectedSize(values.size());
for (BigInteger value : values) {
tokens.add(new ByteOrderedToken(toBytes(value, significantBytes)));
}
return tokens;
}
// Convert a token's byte array to a number in order to perform computations.
// This depends on the number of "significant bytes" that we use to normalize all tokens to the
// same size.
// For example if the token is 0x01 but significantBytes is 2, the result is 8 (0x0100).
private BigInteger toBigInteger(ByteBuffer bb, int significantBytes) {
byte[] bytes = Bytes.getArray(bb);
byte[] target;
if (significantBytes != bytes.length) {
target = new byte[significantBytes];
System.arraycopy(bytes, 0, target, 0, bytes.length);
} else {
target = bytes;
}
return new BigInteger(1, target);
}
// Convert a numeric representation back to a byte array.
// Again, the number of significant bytes matters: if the input value is 1 but significantBytes is
// 2, the
// expected result is 0x0001 (a simple conversion would produce 0x01).
protected ByteBuffer toBytes(BigInteger value, int significantBytes) {
byte[] rawBytes = value.toByteArray();
byte[] result;
if (rawBytes.length == significantBytes) {
result = rawBytes;
} else {
result = new byte[significantBytes];
int start, length;
if (rawBytes[0] == 0) {
// that's a sign byte, ignore (it can cause rawBytes.length == significantBytes + 1)
start = 1;
length = rawBytes.length - 1;
} else {
start = 0;
length = rawBytes.length;
}
System.arraycopy(rawBytes, start, result, significantBytes - length, length);
}
return ByteBuffer.wrap(result);
}
}