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Reduce ByteBuffer duplication when resizing pooled direct ByteBufs (#9765) 

Motivation:

Currently when use of Unsafe is disabled and an internal reallocation is
performed for a direct PooledByteBuf, a one-off temporary duplicate is
made of the source and destination backing nio buffers so that the
copy can be done in a threadsafe manner.

The need for this can be reduced by sharing the temporary duplicate
buffer that is already stored in the corresponding destination
PooledByteBuf instance.

Modifications:

Have PoolArena#memoryCopy(...) take the destination PooledByteBuf
instead of the underlying mem reference and offset, and use
internalNioBuffer() to obtain/initialize a reusable duplicate of the
backing nio buffer.

Result:

Fewer temporary allocations when resizing direct pooled ByteBufs in the
non-Unsafe case
This commit is contained in:
Nick Hill 2019-11-16 11:26:02 -08:00 committed by Norman Maurer
parent 11255c6602
commit c6bdc2b7dc
1 changed files with 8 additions and 8 deletions
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16
buffer/src/main/java/io/netty/buffer/PoolArena.java
View File

@ -402,7 +402,7 @@ abstract class PoolArena<T> implements PoolArenaMetric {
buf.trimIndicesToCapacity(newCapacity);
bytesToCopy = newCapacity;
}
memoryCopy(oldMemory, oldOffset, buf.memory, buf.offset, bytesToCopy);
memoryCopy(oldMemory, oldOffset, buf, bytesToCopy);
if (freeOldMemory) {
free(oldChunk, oldNioBuffer, oldHandle, oldMaxLength, buf.cache);
}
@ -566,7 +566,7 @@ abstract class PoolArena<T> implements PoolArenaMetric {
protected abstract PoolChunk<T> newChunk(int pageSize, int maxOrder, int pageShifts, int chunkSize);
protected abstract PoolChunk<T> newUnpooledChunk(int capacity);
protected abstract PooledByteBuf<T> newByteBuf(int maxCapacity);
protected abstract void memoryCopy(T src, int srcOffset, T dst, int dstOffset, int length);
protected abstract void memoryCopy(T src, int srcOffset, PooledByteBuf<T> dst, int length);
protected abstract void destroyChunk(PoolChunk<T> chunk);
@Override
@ -686,12 +686,12 @@ abstract class PoolArena<T> implements PoolArenaMetric {
}
@Override
protected void memoryCopy(byte[] src, int srcOffset, byte[] dst, int dstOffset, int length) {
protected void memoryCopy(byte[] src, int srcOffset, PooledByteBuf<byte[]> dst, int length) {
if (length == 0) {
return;
}
System.arraycopy(src, srcOffset, dst, dstOffset, length);
System.arraycopy(src, srcOffset, dst.memory, dst.offset, length);
}
}
@ -771,7 +771,7 @@ abstract class PoolArena<T> implements PoolArenaMetric {
}
@Override
protected void memoryCopy(ByteBuffer src, int srcOffset, ByteBuffer dst, int dstOffset, int length) {
protected void memoryCopy(ByteBuffer src, int srcOffset, PooledByteBuf<ByteBuffer> dstBuf, int length) {
if (length == 0) {
return;
}
@ -779,13 +779,13 @@ abstract class PoolArena<T> implements PoolArenaMetric {
if (HAS_UNSAFE) {
PlatformDependent.copyMemory(
PlatformDependent.directBufferAddress(src) + srcOffset,
PlatformDependent.directBufferAddress(dst) + dstOffset, length);
PlatformDependent.directBufferAddress(dstBuf.memory) + dstBuf.offset, length);
} else {
// We must duplicate the NIO buffers because they may be accessed by other Netty buffers.
src = src.duplicate();
dst = dst.duplicate();
ByteBuffer dst = dstBuf.internalNioBuffer();
src.position(srcOffset).limit(srcOffset + length);
dst.position(dstOffset);
dst.position(dstBuf.offset);
dst.put(src);
}
}