uschindler commented on a change in pull request #327:
URL: https://github.com/apache/lucene/pull/327#discussion_r719130968
##########
File path: lucene/core/src/java/org/apache/lucene/util/packed/DirectWriter.java
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@@ -94,38 +91,54 @@ private void flush() throws IOException {
}
// Avoid writing bits from values that are outside of the range we need to
encode
Arrays.fill(nextValues, off, nextValues.length, 0L);
- encode(nextValues, 0, nextBlocks, 0, iterations);
+ encode(nextValues, off, nextBlocks, bitsPerValue);
final int blockCount =
(int) PackedInts.Format.PACKED.byteCount(PackedInts.VERSION_CURRENT,
off, bitsPerValue);
output.writeBytes(nextBlocks, blockCount);
off = 0;
}
- public void encode(
- long[] values, int valuesOffset, byte[] blocks, int blocksOffset, int
iterations) {
- int nextBlock = 0;
- int bitsUsed = 0;
- for (int i = 0; i < byteValueCount * iterations; ++i) {
- final long v = values[valuesOffset++];
- assert PackedInts.unsignedBitsRequired(v) <= bitsPerValue;
- if (bitsUsed < byteOffset) {
- // just buffer
- nextBlock |= v << bitsUsed;
- bitsUsed += bitsPerValue;
- } else {
- // flush as many blocks as possible
- blocks[blocksOffset++] = (byte) (nextBlock | (v << bitsUsed));
- int bits = 8 - bitsUsed;
- while (bits <= bitsUsedOffset) {
- blocks[blocksOffset++] = (byte) (v >> bits);
- bits += 8;
+ private static void encode(long[] nextValues, int upTo, byte[] nextBlocks,
int bitsPerValue) {
+ if ((bitsPerValue & 7) == 0) {
+ // bitsPerValue is a multiple of 8: 8, 16, 24, 32, 30, 48, 56, 64
+ final int bytesPerValue = bitsPerValue / Byte.SIZE;
+ for (int i = 0, o = 0; i < upTo; ++i, o += bytesPerValue) {
Review comment:
> the exception handing is a bit annoying indeed.
The problem is that you cant do much with adapting VarHandles like applying
an explicit cast. To do this you need to convert it to a MethodHandle (which is
internally identical to the VarHandle).
BTW, initially the VarHandles are converted to MethodHandles in the JDK code
until they are optimized away by C2. But the Exceptions are ignored
(MethodHandles are only called from generated bytecode and the exception
handling is simply left out, like in painless).
In JDK 17's Project Panama they added the missing adaptors to do casts:
https://docs.oracle.com/en/java/javase/17/docs/api/jdk.incubator.foreign/jdk/incubator/foreign/MemoryHandles.html#asUnsigned(java.lang.invoke.VarHandle,java.lang.Class)
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