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/*
* (c) Copyright 2018 Palantir Technologies 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.
*/
package com.palantir.atlasdb.keyvalue.api;
import com.google.common.primitives.UnsignedBytes;
import com.palantir.atlasdb.encoding.PtBytes;
import com.palantir.logsafe.Preconditions;
import com.palantir.logsafe.exceptions.SafeIllegalArgumentException;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
public final class RangeRequests {
private RangeRequests() {
// Utility class
}
/**
* This will return the first byte[] less than the given byte[] lexicographically.
*
* If name is the array new byte[] { 0 } an empty byte[] will be returned.
*
* This method will throw if the empty byte array is passed. It will also reject arrays with
* length greater than Cell.MAX_NAME_LENGTH
*/
public static byte[] previousLexicographicName(@Nonnull byte[] name) {
Preconditions.checkArgument(name.length <= Cell.MAX_NAME_LENGTH, "name is too long");
Preconditions.checkArgument(name.length > 0, "name is empty");
if (name[name.length - 1] == 0) {
byte[] ret = new byte[name.length - 1];
System.arraycopy(name, 0, ret, 0, ret.length);
return ret;
}
byte[] ret = new byte[Cell.MAX_NAME_LENGTH];
System.arraycopy(name, 0, ret, 0, name.length);
ret[name.length - 1]--;
for (int i = name.length; i < ret.length; i++) {
ret[i] = (byte) 0xff;
}
return ret;
}
/**
* This will return the row name that will include exactly all prefix matches if passed to
* {@link KeyValueService#getRange(TableReference, RangeRequest, long)}.
*
*
* @param rowName must be non-null
*/
public static byte[] createEndNameForPrefixScan(@Nonnull byte[] rowName) {
Preconditions.checkNotNull(rowName, "name cannot be null");
Preconditions.checkArgument(rowName.length <= Cell.MAX_NAME_LENGTH, "name is too long");
for (int i = rowName.length - 1; i >= 0; i--) {
if ((rowName[i] & 0xff) != 0xff) {
byte[] ret = new byte[i + 1];
System.arraycopy(rowName, 0, ret, 0, i + 1);
ret[i]++;
return ret;
}
}
return PtBytes.EMPTY_BYTE_ARRAY;
}
public static byte[] nextLexicographicName(@Nonnull byte[] name) {
byte[] ret = nextLexicographicNameInternal(name);
if (ret == null) {
throw new SafeIllegalArgumentException("Name is lexicographically maximum and cannot be incremented.");
}
return ret;
}
static final byte[] ONE_AFTER_MAXIMUM_NAME;
static {
ONE_AFTER_MAXIMUM_NAME = new byte[Cell.MAX_NAME_LENGTH + 1];
for (int i = 0; i < Cell.MAX_NAME_LENGTH; ++i) {
ONE_AFTER_MAXIMUM_NAME[i] = (byte) 0xff;
}
ONE_AFTER_MAXIMUM_NAME[Cell.MAX_NAME_LENGTH] = (byte) 0x00;
}
public static byte[] oneAfterMaximumName() {
return ONE_AFTER_MAXIMUM_NAME;
}
/**
* This is a replacement for endRow when doing a non-reverse range request.
*/
public static byte[] endRowExclusiveOrOneAfterMax(RangeRequest rangeRequest) {
Preconditions.checkArgument(!rangeRequest.isReverse());
if (rangeRequest.getEndExclusive().length == 0) {
return oneAfterMaximumName();
}
return rangeRequest.getEndExclusive();
}
/**
* This is a replacement for startRow when doing reverse range request.
*/
public static byte[] startRowInclusiveOrLargestRow(RangeRequest rangeRequest) {
Preconditions.checkArgument(rangeRequest.isReverse());
if (rangeRequest.getStartInclusive().length == 0) {
return getLastRowName();
}
return rangeRequest.getStartInclusive();
}
public static ColumnSelection extractColumnSelection(RangeRequest rangeRequest) {
if (rangeRequest.getColumnNames().isEmpty()) {
return ColumnSelection.all();
}
return ColumnSelection.create(rangeRequest.getColumnNames());
}
private static byte[] nextLexicographicNameInternal(@Nonnull byte[] name) {
Preconditions.checkArgument(name.length <= Cell.MAX_NAME_LENGTH, "name is too long");
if (name.length < Cell.MAX_NAME_LENGTH) {
byte[] ret = new byte[name.length + 1];
System.arraycopy(name, 0, ret, 0, name.length);
ret[name.length] = (byte) 0;
return ret;
} else {
for (int i = name.length - 1; i >= 0; i--) {
if ((name[i] & 0xff) != 0xff) {
byte[] ret = new byte[i + 1];
System.arraycopy(name, 0, ret, 0, i + 1);
ret[i]++;
return ret;
}
}
return null;
}
}
public static byte[] getFirstRowName() {
return new byte[] {0};
}
public static byte[] getLastRowName() {
byte[] ret = new byte[Cell.MAX_NAME_LENGTH];
for (int i = 0; i < ret.length; i++) {
ret[i] = (byte) 0xff;
}
return ret;
}
public static byte[] getLastColumnName() {
return getLastRowName();
}
public static boolean isFirstRowName(boolean reverse, @Nonnull byte[] name) {
return reverse ? isLastRowName(name) : isFirstRowName(name);
}
public static boolean isFirstRowName(@Nonnull byte[] name) {
return name.length == 1 && name[0] == 0;
}
public static boolean isLastRowName(@Nonnull byte[] name) {
if (name.length < Cell.MAX_NAME_LENGTH) {
return false;
}
return nextLexicographicNameInternal(name) == null;
}
public static boolean isLastColumnName(@Nonnull byte[] name) {
return isLastRowName(name);
}
public static boolean isTerminalRow(boolean reverse, @Nonnull byte[] rowName) {
if (reverse) {
return isFirstRowName(rowName);
} else {
return isLastRowName(rowName);
}
}
public static byte[] getNextStartRow(boolean reverse, @Nonnull byte[] rowName) {
if (reverse) {
return previousLexicographicName(rowName);
} else {
return nextLexicographicName(rowName);
}
}
@Nullable
public static byte[] getNextStartRowUnlessTerminal(boolean reverse, @Nonnull byte[] rowName) {
if (reverse) {
if (isFirstRowName(rowName)) {
return null;
} else {
return previousLexicographicName(rowName);
}
} else {
return nextLexicographicNameInternal(rowName);
}
}
public static boolean isContiguousRange(boolean reverse, byte[] startInclusive, byte[] endExclusive) {
if (startInclusive.length == 0 || endExclusive.length == 0) {
return true;
}
if (reverse) {
return UnsignedBytes.lexicographicalComparator().compare(startInclusive, endExclusive) >= 0;
}
return UnsignedBytes.lexicographicalComparator().compare(startInclusive, endExclusive) <= 0;
}
public static boolean isExactlyEmptyRange(byte[] startInclusive, byte[] endExclusive) {
if (startInclusive.length == 0 || endExclusive.length == 0) {
return false;
}
return UnsignedBytes.lexicographicalComparator().compare(startInclusive, endExclusive) == 0;
}
public static RangeRequest ofSingleRow(@Nonnull byte[] row) {
return RangeRequest.builder()
.startRowInclusive(row)
.endRowExclusive(RangeRequests.nextLexicographicName(row))
.build();
}
}