iverase commented on a change in pull request #107: URL: https://github.com/apache/lucene/pull/107#discussion_r622244082
########## File path: lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/packed/LegacyDirectReader.java ########## @@ -0,0 +1,368 @@ +/* + * 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.backward_codecs.packed; + +import java.io.IOException; +import org.apache.lucene.store.RandomAccessInput; +import org.apache.lucene.util.LongValues; + +/** + * Retrieves an instance previously written by {@link LegacyDirectWriter} + * + * <p>Example usage: + * + * <pre class="prettyprint"> + * int bitsPerValue = 100; + * IndexInput in = dir.openInput("packed", IOContext.DEFAULT); + * LongValues values = LegacyDirectReader.getInstance(in.randomAccessSlice(start, end), bitsPerValue); + * for (int i = 0; i < numValues; i++) { + * long value = values.get(i); + * } + * </pre> + * + * @see LegacyDirectWriter + */ +public class LegacyDirectReader { + + private LegacyDirectReader() { + // no instances + } + + /** + * Retrieves an instance from the specified slice written decoding {@code bitsPerValue} for each + * value + */ + public static LongValues getInstance(RandomAccessInput slice, int bitsPerValue) { + return getInstance(slice, bitsPerValue, 0); + } + + /** + * Retrieves an instance from the specified {@code offset} of the given slice decoding {@code + * bitsPerValue} for each value + */ + public static LongValues getInstance(RandomAccessInput slice, int bitsPerValue, long offset) { + switch (bitsPerValue) { + case 1: + return new DirectPackedReader1(slice, offset); + case 2: + return new DirectPackedReader2(slice, offset); + case 4: + return new DirectPackedReader4(slice, offset); + case 8: + return new DirectPackedReader8(slice, offset); + case 12: + return new DirectPackedReader12(slice, offset); + case 16: + return new DirectPackedReader16(slice, offset); + case 20: + return new DirectPackedReader20(slice, offset); + case 24: + return new DirectPackedReader24(slice, offset); + case 28: + return new DirectPackedReader28(slice, offset); + case 32: + return new DirectPackedReader32(slice, offset); + case 40: + return new DirectPackedReader40(slice, offset); + case 48: + return new DirectPackedReader48(slice, offset); + case 56: + return new DirectPackedReader56(slice, offset); + case 64: + return new DirectPackedReader64(slice, offset); + default: + throw new IllegalArgumentException("unsupported bitsPerValue: " + bitsPerValue); + } + } + + static final class DirectPackedReader1 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader1(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + int shift = 7 - (int) (index & 7); + return (in.readByte(offset + (index >>> 3)) >>> shift) & 0x1; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader2 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader2(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + int shift = (3 - (int) (index & 3)) << 1; + return (in.readByte(offset + (index >>> 2)) >>> shift) & 0x3; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader4 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader4(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + int shift = (int) ((index + 1) & 1) << 2; + return (in.readByte(offset + (index >>> 1)) >>> shift) & 0xF; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader8 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader8(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readByte(offset + index) & 0xFF; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader12 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader12(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + long offset = (index * 12) >>> 3; + int shift = (int) ((index + 1) & 1) << 2; + return (in.readShort(this.offset + offset) >>> shift) & 0xFFF; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader16 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader16(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readShort(offset + (index << 1)) & 0xFFFF; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader20 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader20(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + long offset = (index * 20) >>> 3; + // TODO: clean this up... + int v = in.readInt(this.offset + offset) >>> 8; + int shift = (int) ((index + 1) & 1) << 2; + return (v >>> shift) & 0xFFFFF; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader24 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader24(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readInt(offset + index * 3) >>> 8; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader28 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader28(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + long offset = (index * 28) >>> 3; + int shift = (int) ((index + 1) & 1) << 2; + return (in.readInt(this.offset + offset) >>> shift) & 0xFFFFFFFL; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader32 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader32(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readInt(this.offset + (index << 2)) & 0xFFFFFFFFL; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader40 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader40(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readLong(this.offset + index * 5) >>> 24; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader48 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader48(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readLong(this.offset + index * 6) >>> 16; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader56 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader56(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readLong(this.offset + index * 7) >>> 8; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + } + + static final class DirectPackedReader64 extends LongValues { + final RandomAccessInput in; + final long offset; + + DirectPackedReader64(RandomAccessInput in, long offset) { + this.in = in; + this.offset = offset; + } + + @Override + public long get(long index) { + try { + return in.readLong(offset + (index << 3)); + } catch (IOException e) { + throw new RuntimeException(e); Review comment: Same as above, maybe a follow up PR? this is already pretty big. -- This is an automated message from the Apache Git Service. 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