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LUCENE-10125: Another idea of DirectWriter

This commit is contained in:
Uwe Schindler 2021-09-30 00:03:51 +02:00
parent 88b264a368
commit ede0860d54
1 changed files with 41 additions and 16 deletions
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57
lucene/core/src/java/org/apache/lucene/util/packed/DirectWriter.java
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@ -18,6 +18,11 @@ package org.apache.lucene.util.packed;
import java.io.EOFException;
import java.io.IOException;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.invoke.VarHandle;
import java.lang.invoke.VarHandle.AccessMode;
import java.util.Arrays;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.util.BitUtil;
@ -91,28 +96,50 @@ public final class DirectWriter {
}
// Avoid writing bits from values that are outside of the range we need to encode
Arrays.fill(nextValues, off, nextValues.length, 0L);
encode(nextValues, off, nextBlocks, bitsPerValue);
// stupid try-catch-needed because MethodHandle's Throwable and compiler does not allow to
// remove it:
try {
encode(nextValues, off, nextBlocks, bitsPerValue);
} catch (RuntimeException | Error e) {
throw e;
} catch (Throwable e) {
throw new AssertionError(e);
}
final int blockCount =
(int) PackedInts.Format.PACKED.byteCount(PackedInts.VERSION_CURRENT, off, bitsPerValue);
output.writeBytes(nextBlocks, blockCount);
off = 0;
}
private static void encode(long[] nextValues, int upTo, byte[] nextBlocks, int bitsPerValue) {
private static MethodHandle applyLongCast(VarHandle vh) {
return MethodHandles.explicitCastArguments(
vh.toMethodHandle(AccessMode.SET),
MethodType.methodType(void.class, byte[].class, int.class, long.class));
}
private static final MethodHandle MH_LONG_SETTER = applyLongCast(BitUtil.VH_LE_LONG),
MH_INT_SETTER = applyLongCast(BitUtil.VH_LE_INT),
MH_SHORT_SETTER = applyLongCast(BitUtil.VH_LE_SHORT),
MH_BYTE_SETTER = applyLongCast(MethodHandles.arrayElementVarHandle(byte[].class));
private static void encode(long[] nextValues, int upTo, byte[] nextBlocks, int bitsPerValue)
throws Throwable {
if ((bitsPerValue & 7) == 0) {
// bitsPerValue is a multiple of 8: 8, 16, 24, 32, 30, 48, 56, 64
final int bytesPerValue = bitsPerValue / Byte.SIZE;
final MethodHandle setter;
if (bitsPerValue > Integer.SIZE) {
setter = MH_LONG_SETTER;
} else if (bitsPerValue > Short.SIZE) {
setter = MH_INT_SETTER;
} else if (bitsPerValue > Byte.SIZE) {
setter = MH_SHORT_SETTER;
} else {
setter = MH_BYTE_SETTER;
}
for (int i = 0, o = 0; i < upTo; ++i, o += bytesPerValue) {
final long l = nextValues[i];
if (bitsPerValue > Integer.SIZE) {
BitUtil.VH_LE_LONG.set(nextBlocks, o, l);
} else if (bitsPerValue > Short.SIZE) {
BitUtil.VH_LE_INT.set(nextBlocks, o, (int) l);
} else if (bitsPerValue > Byte.SIZE) {
BitUtil.VH_LE_SHORT.set(nextBlocks, o, (short) l);
} else {
nextBlocks[o] = (byte) l;
}
setter.invokeExact(nextBlocks, o, l);
}
} else if (bitsPerValue < 8) {
// bitsPerValue is 1, 2 or 4
@ -128,15 +155,13 @@ public final class DirectWriter {
// bitsPerValue is 12, 20 or 28
// Write values 2 by 2
final int numBytesFor2Values = bitsPerValue * 2 / Byte.SIZE;
final MethodHandle setter =
(bitsPerValue <= Integer.SIZE / 2) ? MH_INT_SETTER : MH_LONG_SETTER;
for (int i = 0, o = 0; i < upTo; i += 2, o += numBytesFor2Values) {
final long l1 = nextValues[i];
final long l2 = nextValues[i + 1];
final long merged = l1 | (l2 << bitsPerValue);
if (bitsPerValue <= Integer.SIZE / 2) {
BitUtil.VH_LE_INT.set(nextBlocks, o, (int) merged);
} else {
BitUtil.VH_LE_LONG.set(nextBlocks, o, merged);
}
setter.invokeExact(nextBlocks, o, merged);
}
}
}