88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
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package channels
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// BatchingChannel implements the Channel interface, with the change that instead of producing individual elements
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// on Out(), it batches together the entire internal buffer each time. Trying to construct an unbuffered batching channel
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// will panic, that configuration is not supported (and provides no benefit over an unbuffered NativeChannel).
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type BatchingChannel struct {
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input, output chan interface{}
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length chan int
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buffer []interface{}
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size BufferCap
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}
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func NewBatchingChannel(size BufferCap) *BatchingChannel {
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if size == None {
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panic("channels: BatchingChannel does not support unbuffered behaviour")
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}
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if size < 0 && size != Infinity {
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panic("channels: invalid negative size in NewBatchingChannel")
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}
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ch := &BatchingChannel{
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input: make(chan interface{}),
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output: make(chan interface{}),
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length: make(chan int),
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size: size,
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}
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go ch.batchingBuffer()
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return ch
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}
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func (ch *BatchingChannel) In() chan<- interface{} {
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return ch.input
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}
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// Out returns a <-chan interface{} in order that BatchingChannel conforms to the standard Channel interface provided
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// by this package, however each output value is guaranteed to be of type []interface{} - a slice collecting the most
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// recent batch of values sent on the In channel. The slice is guaranteed to not be empty or nil. In practice the net
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// result is that you need an additional type assertion to access the underlying values.
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func (ch *BatchingChannel) Out() <-chan interface{} {
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return ch.output
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}
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func (ch *BatchingChannel) Len() int {
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return <-ch.length
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}
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func (ch *BatchingChannel) Cap() BufferCap {
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return ch.size
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}
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func (ch *BatchingChannel) Close() {
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close(ch.input)
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}
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func (ch *BatchingChannel) batchingBuffer() {
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var input, output, nextInput chan interface{}
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nextInput = ch.input
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input = nextInput
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for input != nil || output != nil {
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select {
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case elem, open := <-input:
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if open {
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ch.buffer = append(ch.buffer, elem)
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} else {
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input = nil
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nextInput = nil
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}
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case output <- ch.buffer:
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ch.buffer = nil
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case ch.length <- len(ch.buffer):
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}
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if len(ch.buffer) == 0 {
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input = nextInput
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output = nil
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} else if ch.size != Infinity && len(ch.buffer) >= int(ch.size) {
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input = nil
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output = ch.output
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} else {
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input = nextInput
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output = ch.output
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}
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}
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close(ch.output)
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close(ch.length)
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}
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