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FastLzFrameDecoder should not need to do any extra memory copies even when direct buffers are used (#11511)

Browse Source 
Modifications:

Change code to not depend on heap buffers

Result:

Less memory copies
This commit is contained in:
Norman Maurer 2021-07-26 11:59:02 +02:00
parent 5eb9445990
commit 60c9cbf46a
2 changed files with 29 additions and 37 deletions
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48
codec/src/main/java/io/netty/handler/codec/compression/FastLz.java
View File

@ -15,6 +15,8 @@
*/
package io.netty.handler.codec.compression;
import io.netty.buffer.ByteBuf;
/**
* Core of FastLZ compression algorithm.
*
@ -422,10 +424,10 @@ final class FastLz {
* Decompression is memory safe and guaranteed not to write the output buffer
* more than what is specified in outLength.
*/
static int decompress(final byte[] input, final int inOffset, final int inLength,
final byte[] output, final int outOffset, final int outLength) {
static int decompress(final ByteBuf input, final int inOffset, final int inLength,
final ByteBuf output, final int outOffset, final int outLength) {
//int level = ((*(const flzuint8*)input) >> 5) + 1;
final int level = (input[inOffset] >> 5) + 1;
final int level = (input.getByte(inOffset) >> 5) + 1;
if (level != LEVEL_1 && level != LEVEL_2) {
throw new DecompressionException(String.format(
"invalid level: %d (expected: %d or %d)", level, LEVEL_1, LEVEL_2
@ -437,7 +439,7 @@ final class FastLz {
// flzuint8* op = (flzuint8*) output;
int op = 0;
// flzuint32 ctrl = (*ip++) & 31;
long ctrl = input[inOffset + ip++] & 31;
long ctrl = input.getByte(inOffset + ip++) & 31;
int loop = 1;
do {
@ -457,27 +459,27 @@ final class FastLz {
if (len == 6) {
if (level == LEVEL_1) {
// len += *ip++;
len += input[inOffset + ip++] & 0xFF;
len += input.getUnsignedByte(inOffset + ip++);
} else {
do {
code = input[inOffset + ip++] & 0xFF;
code = input.getUnsignedByte(inOffset + ip++);
len += code;
} while (code == 255);
}
}
if (level == LEVEL_1) {
// ref -= *ip++;
ref -= input[inOffset + ip++] & 0xFF;
ref -= input.getUnsignedByte(inOffset + ip++);
} else {
code = input[inOffset + ip++] & 0xFF;
code = input.getUnsignedByte(inOffset + ip++);
ref -= code;
/* match from 16-bit distance */
// if(FASTLZ_UNEXPECT_CONDITIONAL(code==255))
// if(FASTLZ_EXPECT_CONDITIONAL(ofs==(31 << 8)))
if (code == 255 && ofs == 31 << 8) {
ofs = (input[inOffset + ip++] & 0xFF) << 8;
ofs += input[inOffset + ip++] & 0xFF;
ofs = input.getUnsignedByte(inOffset + ip++) << 8;
ofs += input.getUnsignedByte(inOffset + ip++);
ref = (int) (op - ofs - MAX_DISTANCE);
}
@ -496,7 +498,7 @@ final class FastLz {
}
if (ip < inLength) {
ctrl = input[inOffset + ip++] & 0xFF;
ctrl = input.getUnsignedByte(inOffset + ip++);
} else {
loop = 0;
}
@ -504,12 +506,12 @@ final class FastLz {
if (ref == op) {
/* optimize copy for a run */
// flzuint8 b = ref[-1];
byte b = output[outOffset + ref - 1];
output[outOffset + op++] = b;
output[outOffset + op++] = b;
output[outOffset + op++] = b;
byte b = output.getByte(outOffset + ref - 1);
output.setByte(outOffset + op++, b);
output.setByte(outOffset + op++, b);
output.setByte(outOffset + op++, b);
while (len != 0) {
output[outOffset + op++] = b;
output.setByte(outOffset + op++, b);
--len;
}
} else {
@ -517,12 +519,12 @@ final class FastLz {
ref--;
// *op++ = *ref++;
output[outOffset + op++] = output[outOffset + ref++];
output[outOffset + op++] = output[outOffset + ref++];
output[outOffset + op++] = output[outOffset + ref++];
output.setByte(outOffset + op++, output.getByte(outOffset + ref++));
output.setByte(outOffset + op++, output.getByte(outOffset + ref++));
output.setByte(outOffset + op++, output.getByte(outOffset + ref++));
while (len != 0) {
output[outOffset + op++] = output[outOffset + ref++];
output.setByte(outOffset + op++, output.getByte(outOffset + ref++));
--len;
}
}
@ -537,17 +539,17 @@ final class FastLz {
}
//*op++ = *ip++;
output[outOffset + op++] = input[inOffset + ip++];
output.setByte(outOffset + op++, input.getByte(inOffset + ip++));
for (--ctrl; ctrl != 0; ctrl--) {
// *op++ = *ip++;
output[outOffset + op++] = input[inOffset + ip++];
output.setByte(outOffset + op++, input.getByte(inOffset + ip++));
}
loop = ip < inLength ? 1 : 0;
if (loop != 0) {
// ctrl = *ip++;
ctrl = input[inOffset + ip++] & 0xFF;
ctrl = input.getUnsignedByte(inOffset + ip++);
}
}

18
codec/src/main/java/io/netty/handler/codec/compression/FastLzFrameDecoder.java
View File

@ -148,21 +148,11 @@ public class FastLzFrameDecoder extends ByteToMessageDecoder {
try {
if (isCompressed) {
final byte[] input;
final int inputOffset;
if (in.hasArray()) {
input = in.array();
inputOffset = in.arrayOffset() + idx;
} else {
input = new byte[chunkLength];
in.getBytes(idx, input);
inputOffset = 0;
}
output = ctx.alloc().heapBuffer(originalLength);
int outputOffset = output.arrayOffset() + output.writerIndex();
final int decompressedBytes = decompress(input, inputOffset, chunkLength,
output.array(), outputOffset, originalLength);
output = ctx.alloc().buffer(originalLength);
int outputOffset = output.writerIndex();
final int decompressedBytes = decompress(in, idx, chunkLength,
output, outputOffset, originalLength);
if (originalLength != decompressedBytes) {
throw new DecompressionException(String.format(
"stream corrupted: originalLength(%d) and actual length(%d) mismatch",