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perf(codec-http2): specialize HpackDecoder.decodeULE128 int path #1

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perf(codec-http2): specialize HpackDecoder.decodeULE128 int path #1

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32 changes: 21 additions & 11 deletions codec-http2/src/main/java/io/netty/handler/codec/http2/HpackDecoder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -466,18 +466,28 @@ private static IllegalArgumentException notEnoughDataException(ByteBuf in) {
* Visible for testing only!
*/
static int decodeULE128(ByteBuf in, int result) throws Http2Exception {
final int readerIndex = in.readerIndex();
final long v = decodeULE128(in, (long) result);
if (v > Integer.MAX_VALUE) {
// the maximum value that can be represented by a signed 32 bit number is:
// [0x1,0x7f] + 0x7f + (0x7f << 7) + (0x7f << 14) + (0x7f << 21) + (0x6 << 28)
// OR
// 0x0 + 0x7f + (0x7f << 7) + (0x7f << 14) + (0x7f << 21) + (0x7 << 28)
// we should reset the readerIndex if we overflowed the int type.
in.readerIndex(readerIndex);
throw DECODE_ULE_128_TO_INT_DECOMPRESSION_EXCEPTION;
assert result <= 0x7f && result >= 0;
final boolean resultStartedAtZero = result == 0;
final int writerIndex = in.writerIndex();
for (int readerIndex = in.readerIndex(), shift = 0; readerIndex < writerIndex; ++readerIndex, shift += 7) {
byte b = in.getByte(readerIndex);
if (shift == 28 && ((b & 0x80) != 0 || !resultStartedAtZero && b > 6 || resultStartedAtZero && b > 7)) {
// the maximum value that can be represented by a signed 32 bit number is:
// [0x1,0x7f] + 0x7f + (0x7f << 7) + (0x7f << 14) + (0x7f << 21) + (0x6 << 28)
// OR
// 0x0 + 0x7f + (0x7f << 7) + (0x7f << 14) + (0x7f << 21) + (0x7 << 28)
// this means any more shifts will result in overflow so we should break out and throw an error.
throw DECODE_ULE_128_TO_INT_DECOMPRESSION_EXCEPTION;
}

if ((b & 0x80) == 0) {
in.readerIndex(readerIndex + 1);
return result + ((b & 0x7F) << shift);
}
result += (b & 0x7F) << shift;
}
return (int) v;

throw DECODE_ULE_128_DECOMPRESSION_EXCEPTION;
}

/**
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