with-queued-streaming

Purpose
Queue streaming during evaluation of forms.

Package   :gbbopen

Module   :streaming

Arguments and values

Returns
The values returned by evaluating the last form.

Description
Instead of writing changes directly to a streamer's journal file or network connection, the changes are queued until the last form has been evaluated. Then the queued changes are written as a block that is marked with the tag value. Queued streaming is thread-local (so different threads can have their own open queues at the same time) and with-queued-streaming forms can be nested within a single thread.

If the value of write-empty-queue-p is true, the streamer queue is written even if it is empty (and read-queued-streaming-block will be called with the tag value when the empty queue is received at a streamer node or read during journal loading).

See also
    clear-streamer-queue
    read-queued-streaming-block
    write-streamer-queue

Examples
Assuming that hyp  unit instances are being mirrored to streamer *streamer*, queue the mirroring of a created hyp tagged with the space instance (bb hyps):

  > (with-queued-streaming (*streamer* (find-space-instance-by-path '(bb hyps)))
       (make-instance 'hyp 
          :location (list x y)
          :classification '(:car :truck)
          :color ':red
          :belief .85
          :velocity-range '(5 35)
          :supporting-hyps supporting-hyps))
  #<hyp 419 (1835 4791) 0.85 [5..35]>
  >

Write an empty queue (with tag :empty) to streamer *streamer*:

  > (with-queued-streaming (*streamer* ':empty 't))
  nil
  >

with-queued-streaming