mutating func startProcessing()

in Sources/NIOCore/Codec.swift [287:309]

• 23 lines of code
• 7 McCabe index (conditional complexity)

    mutating func startProcessing(allowEmptyBuffer: Bool) -> BufferAvailability {
        switch self.state {
        case .processingInProgress:
            return .bufferAlreadyBeingProcessed
        case .ready where self.buffers.count > 0:
            var buffer = self.buffers.removeFirst()
            buffer.writeBuffers(self.buffers)
            self.buffers.removeAll(keepingCapacity: self.buffers.capacity < 16) // don't grow too much
            if buffer.readableBytes > 0 || allowEmptyBuffer {
                self.state = .processingInProgress
                return .available(buffer)
            } else {
                return .nothingAvailable
            }
        case .ready:
            assert(self.buffers.isEmpty)
            if allowEmptyBuffer {
                self.state = .processingInProgress
                return .available(self.emptyByteBuffer)
            }
            return .nothingAvailable
        }
    }