jpountz commented on a change in pull request #91: URL: https://github.com/apache/lucene/pull/91#discussion_r630779063
########## File path: lucene/core/src/java/org/apache/lucene/util/StableMSBRadixSorter.java ########## @@ -0,0 +1,78 @@ +/* + * 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.lucene.util; + +/** + * Stable radix sorter for variable-length strings. + * + * @lucene.internal + */ +public abstract class StableMSBRadixSorter extends MSBRadixSorter { + + public StableMSBRadixSorter(int maxLength) { + super(maxLength); + } + + /** Save the i-th value into the j-th position in temporary storage. */ + protected abstract void save(int i, int j); + + /** Restore values between i-th and j-th(excluding) in temporary storage into original storage. */ + protected abstract void restore(int i, int j); + + @Override + protected Sorter getFallbackSorter(int k) { + return new InPlaceMergeSorter() { + @Override + protected void swap(int i, int j) { + StableMSBRadixSorter.this.swap(i, j); + } + + @Override + protected int compare(int i, int j) { + for (int o = k; o < maxLength; ++o) { + final int b1 = byteAt(i, o); + final int b2 = byteAt(j, o); + if (b1 != b2) { + return b1 - b2; + } else if (b1 == -1) { + break; + } + } + return 0; + } + }; + } + + /** + * Reorder elements in stable way, since Dutch sort does not guarantee ordering for same values. + * + * <p>When this method returns, startOffsets and endOffsets are equal. + */ + @Override + protected void reorder(int from, int to, int[] startOffsets, int[] endOffsets, int k) { + int[] assignPos = ArrayUtil.copyOfSubArray(startOffsets, 0, startOffsets.length); Review comment: Could we reuse this array across calls to `reorder`? We could allocate it up-front since it has a known size of `HISTOGRAM_SIZE`? ########## File path: lucene/core/src/java/org/apache/lucene/util/StableMSBRadixSorter.java ########## @@ -0,0 +1,78 @@ +/* + * 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.lucene.util; + +/** + * Stable radix sorter for variable-length strings. + * + * @lucene.internal + */ +public abstract class StableMSBRadixSorter extends MSBRadixSorter { + + public StableMSBRadixSorter(int maxLength) { + super(maxLength); + } + + /** Save the i-th value into the j-th position in temporary storage. */ + protected abstract void save(int i, int j); + + /** Restore values between i-th and j-th(excluding) in temporary storage into original storage. */ + protected abstract void restore(int i, int j); + + @Override + protected Sorter getFallbackSorter(int k) { + return new InPlaceMergeSorter() { + @Override + protected void swap(int i, int j) { + StableMSBRadixSorter.this.swap(i, j); + } + + @Override + protected int compare(int i, int j) { + for (int o = k; o < maxLength; ++o) { + final int b1 = byteAt(i, o); Review comment: Thanks, I was confused. :) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
