Package groovy.concurrent

Class ChannelSelect

java.lang.Object
groovy.concurrent.ChannelSelect
public final class ChannelSelect extends Object
Selects the first available value from multiple AsyncChannels.

This is the channel equivalent of Awaitable.any(Object...) — while Awaitable.any races futures, ChannelSelect races channel receives. Each call to select() returns an Awaitable that completes with a ChannelSelect.Result indicating which channel produced the value and what it was. 


 def prices = AsyncChannel.create(10)
 def alerts = AsyncChannel.create(10)

 def sel = ChannelSelect.from(prices, alerts)
 def result = await sel.select()
 println "Channel ${result.index}: ${result.value}"

Inspired by GPars' Select and Go's select statement.

Since:
6.0.0

  • Method Details

    • from

      @SafeVarargs public static ChannelSelect from(AsyncChannel<?>... channels)
      Creates a select over the given channels.
      Parameters:
      channels - the channels to select from
      Returns:
      a new ChannelSelect

    • select

      public Awaitable<ChannelSelect.Result> select()
      Waits for the first value available from any of the channels.

      Returns an Awaitable that completes with a ChannelSelect.Result containing the channel index and the received value.

      Values consumed by non-winning channels are re-sent back to those channels to prevent message loss. This may reorder values within a channel but guarantees no values are silently dropped.

      Returns:
      an awaitable result indicating which channel produced the value