e329cc3524
Avoid calling CompositeChannelBuffer.decompose. A more efficient frame deocder specific implementation is used that avoids some of the cost of decomposing a CompositeChannelBuffer. Added setMaxUnusedBufferCapacity to set a threshold. If a cumulation buffer wastes more space than the threshold, the decoder will resort to copying the buffer to free up the unused space. The semantics are different from FrameDecoder's setMaxCumulationBufferCapacity in that the threshold is for unused space, not buffer capacity. This allows the copy of large buffers to be avoided if only a small amount of space is to be gained. If a copy is invoked, only the actual fragment is copied, not the complete cummulation buffer. This reduces the cost of copying the buffer.