Implement SWAR indexOf byte search (#10737)
Motivation: Faster indexOf Modification: Create generic SWAR indexOf that any ByteBuf implementation can use Result: Fixes #10731
This commit is contained in:
Francesco Nigro
GitHub
parent
bba0017d6e
commit
9a02832fdb
@ -1251,43 +1251,9 @@ public abstract class AbstractByteBuf extends ByteBuf {
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@Override
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public int indexOf(int fromIndex, int toIndex, byte value) {
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if (fromIndex <= toIndex) {
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return firstIndexOf(fromIndex, toIndex, value);
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} else {
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return lastIndexOf(fromIndex, toIndex, value);
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return ByteBufUtil.firstIndexOf(this, fromIndex, toIndex, value);
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}
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}
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private int firstIndexOf(int fromIndex, int toIndex, byte value) {
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fromIndex = Math.max(fromIndex, 0);
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if (fromIndex >= toIndex || capacity() == 0) {
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return -1;
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}
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checkIndex(fromIndex, toIndex - fromIndex);
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for (int i = fromIndex; i < toIndex; i ++) {
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if (_getByte(i) == value) {
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return i;
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}
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}
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return -1;
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}
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private int lastIndexOf(int fromIndex, int toIndex, byte value) {
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fromIndex = Math.min(fromIndex, capacity());
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if (fromIndex < 0 || capacity() == 0) {
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return -1;
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}
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checkIndex(toIndex, fromIndex - toIndex);
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for (int i = fromIndex - 1; i >= toIndex; i --) {
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if (_getByte(i) == value) {
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return i;
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}
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}
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return -1;
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return ByteBufUtil.lastIndexOf(this, fromIndex, toIndex, value);
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}
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@Override
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@ -389,16 +389,124 @@ public final class ByteBufUtil {
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return 0;
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}
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private static final class SWARByteSearch {
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private static long compilePattern(byte byteToFind) {
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return (byteToFind & 0xFFL) * 0x101010101010101L;
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}
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private static int firstAnyPattern(long word, long pattern, boolean leading) {
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long input = word ^ pattern;
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long tmp = (input & 0x7F7F7F7F7F7F7F7FL) + 0x7F7F7F7F7F7F7F7FL;
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tmp = ~(tmp | input | 0x7F7F7F7F7F7F7F7FL);
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final int binaryPosition = leading? Long.numberOfLeadingZeros(tmp) : Long.numberOfTrailingZeros(tmp);
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return binaryPosition >>> 3;
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}
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}
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private static int unrolledFirstIndexOf(AbstractByteBuf buffer, int fromIndex, int byteCount, byte value) {
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assert byteCount > 0 && byteCount < 8;
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if (buffer._getByte(fromIndex) == value) {
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return fromIndex;
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}
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if (byteCount == 1) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 1) == value) {
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return fromIndex + 1;
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}
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if (byteCount == 2) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 2) == value) {
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return fromIndex + 2;
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}
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if (byteCount == 3) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 3) == value) {
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return fromIndex + 3;
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}
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if (byteCount == 4) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 4) == value) {
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return fromIndex + 4;
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}
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if (byteCount == 5) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 5) == value) {
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return fromIndex + 5;
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}
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if (byteCount == 6) {
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return -1;
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}
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if (buffer._getByte(fromIndex + 6) == value) {
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return fromIndex + 6;
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}
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return -1;
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}
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/**
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* This is using a SWAR (SIMD Within A Register) batch read technique to minimize bound-checks and improve memory
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* usage while searching for {@code value}.
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*/
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static int firstIndexOf(AbstractByteBuf buffer, int fromIndex, int toIndex, byte value) {
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fromIndex = Math.max(fromIndex, 0);
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if (fromIndex >= toIndex || buffer.capacity() == 0) {
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return -1;
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}
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final int length = toIndex - fromIndex;
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buffer.checkIndex(fromIndex, length);
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if (!PlatformDependent.isUnaligned()) {
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return linearFirstIndexOf(buffer, fromIndex, toIndex, value);
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}
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assert PlatformDependent.isUnaligned();
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int offset = fromIndex;
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final int byteCount = length & 7;
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if (byteCount > 0) {
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final int index = unrolledFirstIndexOf(buffer, fromIndex, byteCount, value);
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if (index != -1) {
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return index;
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}
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offset += byteCount;
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if (offset == toIndex) {
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return -1;
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}
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}
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final int longCount = length >>> 3;
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final ByteOrder nativeOrder = ByteOrder.nativeOrder();
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final boolean isNative = nativeOrder == buffer.order();
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final boolean useLE = nativeOrder == ByteOrder.LITTLE_ENDIAN;
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final long pattern = SWARByteSearch.compilePattern(value);
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for (int i = 0; i < longCount; i++) {
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// use the faster available getLong
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final long word = useLE? buffer._getLongLE(offset) : buffer._getLong(offset);
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int index = SWARByteSearch.firstAnyPattern(word, pattern, isNative);
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if (index < Long.BYTES) {
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return offset + index;
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}
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offset += Long.BYTES;
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}
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return -1;
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}
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private static int linearFirstIndexOf(AbstractByteBuf buffer, int fromIndex, int toIndex, byte value) {
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for (int i = fromIndex; i < toIndex; i++) {
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if (buffer._getByte(i) == value) {
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return i;
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}
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}
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return -1;
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}
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/**
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* The default implementation of {@link ByteBuf#indexOf(int, int, byte)}.
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* This method is useful when implementing a new buffer type.
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*/
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public static int indexOf(ByteBuf buffer, int fromIndex, int toIndex, byte value) {
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if (fromIndex <= toIndex) {
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return firstIndexOf(buffer, fromIndex, toIndex, value);
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} else {
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return lastIndexOf(buffer, fromIndex, toIndex, value);
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}
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return buffer.indexOf(fromIndex, toIndex, value);
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}
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/**
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@ -477,23 +585,21 @@ public final class ByteBufUtil {
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}
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}
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private static int firstIndexOf(ByteBuf buffer, int fromIndex, int toIndex, byte value) {
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fromIndex = Math.max(fromIndex, 0);
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if (fromIndex >= toIndex || buffer.capacity() == 0) {
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return -1;
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}
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return buffer.forEachByte(fromIndex, toIndex - fromIndex, new ByteProcessor.IndexOfProcessor(value));
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}
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private static int lastIndexOf(ByteBuf buffer, int fromIndex, int toIndex, byte value) {
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int capacity = buffer.capacity();
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static int lastIndexOf(AbstractByteBuf buffer, int fromIndex, int toIndex, byte value) {
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assert fromIndex > toIndex;
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final int capacity = buffer.capacity();
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fromIndex = Math.min(fromIndex, capacity);
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if (fromIndex < 0 || capacity == 0) {
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return -1;
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}
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buffer.checkIndex(toIndex, fromIndex - toIndex);
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for (int i = fromIndex - 1; i >= toIndex; i--) {
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if (buffer._getByte(i) == value) {
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return i;
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}
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}
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return buffer.forEachByteDesc(toIndex, fromIndex - toIndex, new ByteProcessor.IndexOfProcessor(value));
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return -1;
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}
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private static CharSequence checkCharSequenceBounds(CharSequence seq, int start, int end) {
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@ -2122,6 +2122,36 @@ public abstract class AbstractByteBufTest {
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}
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}
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@Test
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public void testSWARIndexOf() {
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ByteBuf buffer = newBuffer(16);
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buffer.clear();
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// Ensure the buffer is completely zero'ed.
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buffer.setZero(0, buffer.capacity());
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buffer.writeByte((byte) 0); // 0
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0); // 7
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 0);
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buffer.writeByte((byte) 1); // 11
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buffer.writeByte((byte) 2);
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buffer.writeByte((byte) 3);
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buffer.writeByte((byte) 4);
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buffer.writeByte((byte) 1);
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assertEquals(11, buffer.indexOf(0, 12, (byte) 1));
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assertEquals(12, buffer.indexOf(0, 16, (byte) 2));
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assertEquals(-1, buffer.indexOf(0, 11, (byte) 1));
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assertEquals(11, buffer.indexOf(0, 16, (byte) 1));
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buffer.release();
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}
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@Test
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public void testIndexOf() {
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buffer.clear();
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@ -0,0 +1,114 @@
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/*
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* Copyright 2020 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.microbench.buffer;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufAllocator;
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import io.netty.buffer.PooledByteBufAllocator;
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import io.netty.buffer.UnpooledByteBufAllocator;
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import io.netty.microbench.util.AbstractMicrobenchmark;
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import io.netty.util.internal.SuppressJava6Requirement;
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import org.openjdk.jmh.annotations.Benchmark;
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import org.openjdk.jmh.annotations.Fork;
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import org.openjdk.jmh.annotations.Level;
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import org.openjdk.jmh.annotations.Measurement;
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import org.openjdk.jmh.annotations.OutputTimeUnit;
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import org.openjdk.jmh.annotations.Param;
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import org.openjdk.jmh.annotations.Scope;
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import org.openjdk.jmh.annotations.Setup;
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import org.openjdk.jmh.annotations.State;
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import org.openjdk.jmh.annotations.TearDown;
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import org.openjdk.jmh.annotations.Warmup;
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import java.util.SplittableRandom;
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import java.util.concurrent.TimeUnit;
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@State(Scope.Benchmark)
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@OutputTimeUnit(TimeUnit.MICROSECONDS)
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@Fork(2)
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@Warmup(iterations = 5, time = 1)
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@Measurement(iterations = 8, time = 1)
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public class ByteBufIndexOfBenchmark extends AbstractMicrobenchmark {
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@Param({ "7", "16", "23", "32" })
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int size;
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@Param({ "4", "11" })
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int logPermutations;
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@Param({ "1" })
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int seed;
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int permutations;
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ByteBuf[] data;
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private int i;
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@Param({ "0" })
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private byte needleByte;
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@Param({ "true", "false" })
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private boolean direct;
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@Param({ "false", "true" })
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private boolean noUnsafe;
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@Param({ "false", "true" })
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private boolean pooled;
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@Setup(Level.Trial)
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@SuppressJava6Requirement(reason = "using SplittableRandom to reliably produce data")
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public void init() {
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System.setProperty("io.netty.noUnsafe", Boolean.valueOf(noUnsafe).toString());
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SplittableRandom random = new SplittableRandom(seed);
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permutations = 1 << logPermutations;
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this.data = new ByteBuf[permutations];
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final ByteBufAllocator allocator = pooled? PooledByteBufAllocator.DEFAULT : UnpooledByteBufAllocator.DEFAULT;
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for (int i = 0; i < permutations; ++i) {
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data[i] = direct? allocator.directBuffer(size, size) : allocator.heapBuffer(size, size);
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for (int j = 0; j < size; j++) {
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int value = random.nextInt(Byte.MIN_VALUE, Byte.MAX_VALUE + 1);
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// turn any found value into something different
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if (value == needleByte) {
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if (needleByte != 1) {
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value = 1;
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} else {
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value = 0;
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}
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}
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data[i].setByte(j, value);
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}
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final int foundIndex = random.nextInt(Math.max(0, size - 8), size);
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data[i].setByte(foundIndex, needleByte);
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}
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}
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private ByteBuf getData() {
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return data[i++ & (permutations - 1)];
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}
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@Benchmark
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public int indexOf() {
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return getData().indexOf(0, size, needleByte);
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}
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@TearDown
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public void releaseBuffers() {
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for (ByteBuf buffer : data) {
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buffer.release();
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}
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}
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}
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