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6.14 Ring Buffer

The (goblins actor-lib ring-buffer) module provides an actor implementing a ring buffer data structure.

Constructor: ^ring-buffer capacity ¶

Construct new ^ring-buffer actor with a capacity of capacity.

The actor has the following methods:

• empty?: Return #t if ring buffer is empty.
• full?: Return #t if ring buffer is full.
• capacity: Return the capacity of the ring buffer.
• length: Return the number of items currently stored in the ring buffer.
• put value: Append value to the ring buffer.
• take: Dequeue an item from the ring buffer.
• ref index: Return the item index within the ring buffer.
• head amount: Return up to amount items from the front of the ring buffer (i.e. the oldest items).
• tail amount: Return up to amount items from the end of the ring buffer (i.e. the newest items).
• resize new-capacity: Resizes the ring buffer to have a new capacity of new-capacity. If the new-capacity is smaller than the current capacity the oldest items within the ring buffer will be dropped.
• clear: Removes all items from the ring buffer, returning it to be empty.

> (define ring-buffer (spawn ^ring-buffer 5))
> ($ ring-buffer 'empty?)
=> #t
> ($ ring-buffer 'put 'one)
> ($ ring-buffer 'put 'two)
> ($ ring-buffer 'put 'three)
> ($ ring-buffer 'put 'four)
> ($ ring-buffer 'put 'five)
> ($ ring-buffer 'head 5)
=> (one two three four five)
> ($ ring-buffer 'put 'six)
> ($ ring-buffer 'head 5)
=> (two three four five six)
> ($ ring-buffer 'resize 3)
> ($ ring-buffer 'head 3)
=> (four five six)
> ($ ring-buffer 'take)
=> four
> ($ ring-buffer 'full?)
=> #f

Persistence Environment: ring-buffer-env ¶