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kill solver threads

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Matthew Butterick 3 years ago
parent bb3e5655e3
commit ca615dc293
1 changed files with 59 additions and 49 deletions
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108
csp/csp/hacs.rkt
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@ -437,8 +437,8 @@
(when-debug (set! nfchecks (+ (length checked-vars) nchecks)))
;; conflict-set will be empty if there are no empty domains (as we would hope)
(define conflict-set (for/list ([cvr (in-list checked-vars)]
#:when (set-empty? (domain cvr)))
(history cvr)))
#:when (set-empty? (domain cvr)))
(history cvr)))
;; for conflict-directed backjumping it's essential to forward-check ALL vars
;; (even after an empty domain is generated) and combine their conflicts
;; so we can discover the *most recent past var* that could be the culprit.
@ -512,46 +512,51 @@
[val (in-list (map cdr assocs))])
(equal? x val))))
(struct solver (generator kill) #:transparent
#:property prop:procedure 0)
(define/contract (backtracking-solver
prob
#:select-variable [select-unassigned-variable
(or (current-select-variable) first-unassigned-variable)]
#:order-values [order-domain-values (or (current-order-values) first-domain-value)]
#:inference [inference (or (current-inference) forward-check)])
((csp?) (#:select-variable procedure? #:order-values procedure? #:inference procedure?) . ->* . generator?)
(generator ()
(define starting-state-count (state-count prob))
(define states-examined 0)
(define reduce-arity-proc (if (current-arity-reduction) reduce-constraint-arity values))
(let loop ([prob ((if (current-node-consistency) make-nodes-consistent values) prob)])
(match (select-unassigned-variable prob)
[#false (yield prob)]
[(var name domain)
(define (wants-backtrack? exn)
(and (backtrack? exn) (or (let ([bths (backtrack-histories exn)])
(or (empty? bths) (for*/or ([bth (in-list bths)]
[rec (in-list bth)])
(eq? name (car rec))))))))
(for/fold ([conflicts null]
#:result (void))
([val (in-list (order-domain-values (set->list domain)))])
(with-handlers ([wants-backtrack?
(λ (bt)
(define bths (backtrack-histories bt))
(append conflicts (remq name (remove-duplicates
(for*/list ([bth (in-list bths)]
[rec (in-list bth)])
(car rec)) eq?))))])
(let* ([prob (assign-val prob name val)]
;; reduce constraints before inference,
;; to create more forward-checkable (binary) constraints
[prob (reduce-arity-proc prob)]
[prob (inference prob name)]
[prob (check-constraints prob)])
(loop prob))
;; conflicts goes inside the handler expression
;; so raises can supersede it
conflicts))]))))
((csp?) (#:select-variable procedure? #:order-values procedure? #:inference procedure?) . ->* . solver?)
(solver
(generator ()
(define starting-state-count (state-count prob))
(define states-examined 0)
(define reduce-arity-proc (if (current-arity-reduction) reduce-constraint-arity values))
(let loop ([prob ((if (current-node-consistency) make-nodes-consistent values) prob)])
(match (select-unassigned-variable prob)
[#false (yield prob)]
[(var name domain)
(define (wants-backtrack? exn)
(and (backtrack? exn) (or (let ([bths (backtrack-histories exn)])
(or (empty? bths) (for*/or ([bth (in-list bths)]
[rec (in-list bth)])
(eq? name (car rec))))))))
(for/fold ([conflicts null]
#:result (void))
([val (in-list (order-domain-values (set->list domain)))])
(with-handlers ([wants-backtrack?
(λ (bt)
(define bths (backtrack-histories bt))
(append conflicts (remq name (remove-duplicates
(for*/list ([bth (in-list bths)]
[rec (in-list bth)])
(car rec)) eq?))))])
(let* ([prob (assign-val prob name val)]
;; reduce constraints before inference,
;; to create more forward-checkable (binary) constraints
[prob (reduce-arity-proc prob)]
[prob (inference prob name)]
[prob (check-constraints prob)])
(loop prob))
;; conflicts goes inside the handler expression
;; so raises can supersede it
conflicts))])))
void))
(define/contract (random-pick xs)
((non-empty-listof any/c) . -> . any/c)
@ -580,12 +585,16 @@
(assign-val prob name val)]))))))
(define/contract (min-conflicts-solver prob [max-steps 100])
((csp?) (exact-positive-integer?) . ->* . generator?)
(generator ()
(for ([thread-count (or (current-thread-count) 1)]) ; todo: what is ideal thread count?
(make-min-conflcts-thread prob thread-count max-steps))
(for ([i (in-naturals)])
(yield (thread-receive)))))
((csp?) (exact-positive-integer?) . ->* . solver?)
; todo: what is ideal thread count?
(define threads (for/list ([thread-count (or (current-thread-count) 1)])
(make-min-conflcts-thread prob thread-count max-steps)))
(solver
(generator ()
(let loop ()
(yield (thread-receive))
(loop)))
(λ () (for-each kill-thread threads) )))
(define/contract (optimal-stop-min proc xs)
(procedure? (listof any/c) . -> . any/c)
@ -660,18 +669,20 @@
(extract-subcsp prob nodeset))
(list prob)))
(define (make-solution-generator prob)
(define (make-solution-generator prob max-solutions)
(generator ()
(define subprobs (decompose-prob prob))
(define solgens (map (current-solver) subprobs))
(define solstreams (for/list ([solgen (in-list solgens)])
(for/stream ([sol (in-producer solgen (void))])
sol)))
(for ([solution-pieces (in-cartesian solstreams)])
(yield (combine-csps solution-pieces)))))
(for ([solution-pieces (in-cartesian solstreams)]
[count (in-range max-solutions)])
(yield (combine-csps solution-pieces)))
(for-each solver-kill solgens)))
(define-syntax-rule (in-solutions PROB)
(in-producer (make-solution-generator PROB) (void)))
(define-syntax-rule (in-solutions PROB MAX-SOLUTIONS)
(in-producer (make-solution-generator PROB MAX-SOLUTIONS) (void)))
(define/contract (solve* prob [max-solutions +inf.0]
#:finish-proc [finish-proc (λ (p) (csp->assocs p (map var-name (vars prob))))]
@ -680,8 +691,7 @@
(when-debug (reset-nassns!) (reset-nfchecks!) (reset-nchecks!))
(parameterize ([current-solver (or solver (current-solver) backtracking-solver)])
(for/list ([sol (in-solutions prob)]
[idx (in-range max-solutions)])
(for/list ([sol (in-solutions prob max-solutions)])
(finish-proc sol))))
(define/contract (solve prob

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