jpountz commented on a change in pull request #973: LUCENE-9027: Use SIMD instructions to decode postings. URL: https://github.com/apache/lucene-solr/pull/973#discussion_r347372434
########## File path: lucene/core/src/java/org/apache/lucene/codecs/lucene84/PForUtil.java ########## @@ -0,0 +1,130 @@ +/* + * 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.codecs.lucene84; + +import java.io.IOException; +import java.util.Arrays; + +import org.apache.lucene.store.DataInput; +import org.apache.lucene.store.DataOutput; +import org.apache.lucene.util.packed.PackedInts; + +/** + * Utility class to encode sequences of 128 small positive integers. + */ +final class PForUtil { + + static boolean allEqual(long[] l) { + for (int i = 1; i < ForUtil.BLOCK_SIZE; ++i) { + if (l[i] != l[0]) { + return false; + } + } + return true; + } + + private final ForUtil forUtil; + + PForUtil(ForUtil forUtil) { + this.forUtil = forUtil; + } + + /** + * Encode 128 integers from {@code longs} into {@code out}. + */ + void encode(long[] longs, DataOutput out) throws IOException { + // At most 3 exceptions + final long[] top4 = new long[4]; + Arrays.fill(top4, -1L); + for (int i = 0; i < ForUtil.BLOCK_SIZE; ++i) { + if (longs[i] > top4[0]) { + top4[0] = longs[i]; + Arrays.sort(top4); // For only 4 entries we just sort on every iteration instead of maintaining a PQ Review comment: Yes, I would be surprised if that made a different for 4 slots. ---------------------------------------------------------------- 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 With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
