Daerth

Daerth , by PYK, is a multi-threaded system providing queues and transport who consume from one queue and feed another.

Description

Each queue is in its own thread. Each transport is given a source queue to consume from and a destination queue to feed. Queue operations block until successful. Blocking is implemented via coroutines: Any script performing queue operations must run in a coroutine context, and every queue operation suspends the coroutine which is then woken up later by an acknowledgement from the queue. When a queue is empty and there are no more feeders, take returns a code of break. Worker threads end automatically. Queues are deleted by the user.

A transport typically calls daerth deliver in a loop which is broken when the queue is exhausted.

Synopsis

daerth queue .spawn cmdname
Create a new queue.
daerth pipeline name producers ?transports ...?
A produer is produced for each item in producers and that item is passed to the producer as its work argument. A transport is produced for each item in each transports list, and that item becomes its args list. Queues are created between each group of producers and transports. A new command named name is created. Each time it is called it returns one result from the final queue, or if the pipeline is exhausted it returns a code of break and deletes itself and all relevant queues.
daerth producer queue work
Create a new producer to feed a queue. work is a list of arguments to pass to apply, and when it is applied the fully-qualified name of the command for the daerth system is passed as the last argument.
daerth transport source dest args
source is the thread for the source queue, dest is the thread for the destination queue, args is a list of arguments to apply, as described for daerth producer is a list of arguments to apply. The name of the transport command is passed to this procedure as the first argument.

Transport commands

take
Take one item from the source queue. Returns the item, or -code break if the queue is empty.
deliver
Deliver a value to the destination queue and take one item from the source queue.

Queue commands

init
Initialize the queue.
exit
Finalize the queue and release the thread for it.

Station commands

count
The number of transports to create.
transport
A list whose items are passed as the arguments to transport.

Examples

See the test suite .