Add reazon-run-with-config and 'timeout' option

[ethan-leba]

Hi again Nick,

As the title states this PR introduces a new run endpoint, reazon-run-with-config, and the current only config option is :timeout, which specifies what the maximum time a query can run for.

An :check-occurs config option could also be added later on to disable that feature for more performance.

My personal usecase for this is running reazon queries with an infinite search space interactively, where it either quickly succeeds or runs forever. Without this modification, you'd have to C-g out of every failed search.

Let me know if this looks OK!

[nickdrozd]

That's a cool idea. I'll take a look.

What sorts of queries are you running?

[nickdrozd]

Suggested change

	(define-error 'reazon-timeout-error "The reazon query has exceeded it's time limit")
	(define-error 'reazon-timeout
	"The reazon query has exceeded its time limit")

[nickdrozd]

Suggested change

	(result (list (car stream))))
	(ignore-error 'reazon-timeout-error
	(let ((rest (reazon--pull (cdr stream) stop-time)))
	(while (and rest (not (zerop count)))
	(setq count (1- count))
	(setq result (cons (car rest) result))
	(setq rest (reazon--pull (cdr rest) stop-time)))))
	(let ((count (if n (1- n) -1))
	(result (list (car stream)))
	(rest (ignore-error 'reazon-timeout-error
	(reazon--pull (cdr stream) stop-time))))
	(while (and rest (not (zerop count)))
	(setq count (1- count))
	(setq result (cons (car rest) result))
	(setq rest (ignore-error 'reazon-timeout-error
	(reazon--pull (cdr rest) stop-time))))
	(nreverse result))))

[nickdrozd]

This is written as a while loop, but it's really a do-while loop. Does Elisp have that? Otherwise there's this ugly duplication. (This is a pre-existing problem.)

[ethan-leba]

i don't think so unfortunately, but the new exception-less impl. doesn't have duplication anymore

[nickdrozd]

Does this really need to throw an error? If the timeout is reached, then it will just return whatever it's gotten so far, right? Maybe it could just break the while loop here and return.

On the other hand, the user might want to know if their query has stopped because it reached the end or because it hit a timeout and there was still more to do.

[nickdrozd]

Suggested change

	(declare (indent 2))
	(if (listp var/list)
	(let ((vars var/list)
	(q (gensym)))
	`(reazon-run-with-config ,n ,q ,config
	(reazon-fresh ,vars
	(reazon-== (list ,@vars) ,q)
	,@goals)))
	(let ((var var/list))
	`(let ((,var (reazon--make-variable ',var))
	(stop-time (and (plist-get ,config :timeout)
	(+ (plist-get ,config :timeout) (float-time)))))
	(mapcar
	(reazon--reify ,var)
	(reazon--take ,n (reazon--run-goal (reazon-conj ,@goals) stop-time) stop-time))))))
	(declare (indent 3))
	(if (listp var/list)
	(let ((vars var/list)
	(q (gensym)))
	`(reazon-run-with-config ,n ,q ,config
	(reazon-fresh ,vars
	(reazon-== (list ,@vars) ,q)
	,@goals)))
	(let ((var var/list))
	`(let ((,var (reazon--make-variable ',var))
	(stop-time (and (plist-get ,config :timeout)
	(+ (plist-get ,config :timeout) (float-time)))))
	(mapcar
	(reazon--reify ,var)
	(reazon--take ,n (reazon--run-goal (reazon-conj ,@goals) stop-time) stop-time))))))

[nickdrozd]

Is there a way to do the plist-get just once?

[nickdrozd]

An :check-occurs config option could also be added later on to disable that feature for more performance.

#6, for reference.

[nickdrozd]

@ebpa, what do you think?

[nickdrozd]

Suggested change

	(ert-deftest reazon-test-interface-run-with-config ()
	(reazon--should-equal '()
	(reazon-run-with-config nil q '(:timeout 0.01) (reazon-test--nevero)))
	(should (consp (reazon-run-with-config nil q '(:timeout 0.01) (reazon-test--alwayso)))))
	(ert-deftest reazon-test-interface-run-with-config ()
	(reazon--should-equal '()
	(reazon-run-with-config nil q '(:timeout 0.01)
	(reazon-test--nevero)))
	(should
	(consp
	(reazon-run-with-config nil q '(:timeout 0.01)
	(reazon-test--alwayso)))))

[nickdrozd]

Can we do any better than consp?

[ethan-leba]

Switched this to a length >3 check, abritrarily chose 3

[ethan-leba]

Removed the exception handling, and went for a different (and i think more idiomatic) approach for how the configuration gets passed in. Inspired by json-read, it expects users to let-bind configuration options. This'll also be helpful for toggling occurs, as explicitly passing that parameter around would be a nightmare!

[ethan-leba]

That's a cool idea. I'll take a look.

What sorts of queries are you running?

I'm using reazon as a code generation engine for a structural editing plugin -- so the queries are asking for a list of tokens that parse for a given grammar, along with some extra criteria.

[nickdrozd]

I'm using reazon as a code generation engine for a structural editing plugin -- so the queries are asking for a list of tokens that parse for a given grammar, along with some extra criteria.

If you have that up somewhere I would love to take a look. I've mostly used Reazon for logic puzzles and generating instances of stuff (for instance, https://nickdrozd.github.io/2018/08/14/modal-sentences.html).

[nickdrozd]

Agreed that this approach is more idiomatic, and it's simpler too. Thanks!

[ethan-leba]

It's still very much a WIP, but I just put the repo on GH -- here's a link to the reazon section: https://github.com/ethan-leba/tree-edit/blob/main/tree-edit.el#L560