2013-10-26 18:14:11 +00:00
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#lang racket/base
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2013-10-28 19:08:24 +00:00
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(require racket/match)
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2013-10-26 18:14:11 +00:00
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(require "core.rkt")
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(require "presence-detector.rkt")
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(provide (except-out (struct-out demand-matcher) demand-matcher)
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(rename-out [make-demand-matcher demand-matcher])
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2013-10-28 19:08:24 +00:00
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demand-matcher-update
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spawn-demand-matcher)
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2013-10-26 18:14:11 +00:00
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2013-10-28 19:08:24 +00:00
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(struct demand-matcher (demand-is-subscription?
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pattern
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meta-level
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demand-level
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supply-level
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increase-handler
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decrease-handler
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state)
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2013-10-26 18:14:11 +00:00
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#:transparent)
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(define (unexpected-supply-decrease r)
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2013-10-30 14:42:27 +00:00
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'())
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2013-10-28 19:08:24 +00:00
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2013-10-26 18:14:11 +00:00
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(define (default-decrease-handler removed state)
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state)
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2013-10-26 18:14:11 +00:00
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2013-10-28 19:08:24 +00:00
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(define (make-demand-matcher demand-is-subscription?
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pattern
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meta-level
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demand-level
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supply-level
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increase-handler
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[decrease-handler default-decrease-handler])
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(demand-matcher demand-is-subscription?
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pattern
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meta-level
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demand-level
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supply-level
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2013-10-26 18:14:11 +00:00
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increase-handler
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decrease-handler
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(presence-detector)))
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2013-10-28 19:08:24 +00:00
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(define (compute-detector demand? d)
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(route (if (demand-matcher-demand-is-subscription? d) (not demand?) demand?)
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(demand-matcher-pattern d)
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(demand-matcher-meta-level d)
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(+ 1 (max (demand-matcher-demand-level d)
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(demand-matcher-supply-level d)))))
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;; For each route "changed" in routes, if changed is one of our
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;; monitored entities (a demand, if arrivals? is #t, or a supply
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;; otherwise), including both a pattern, meta-level, and level match,
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;; then search for matching peers (including level matching). If
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;; arrivals? is #t, then if there are no matching peers (i.e. supplies
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;; are not allocated), signel an increas in demand; otherwise, if
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;; there are any matching peers (i.e. demand remains), signal a
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;; decrease in supply.
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(define (incorporate-delta arrivals? routes d state)
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(define relevant-change-detector (compute-detector arrivals? d))
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(define expected-change-level
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(if arrivals? (demand-matcher-demand-level d) (demand-matcher-supply-level d)))
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(define expected-peer-level
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(if arrivals? (demand-matcher-supply-level d) (demand-matcher-demand-level d)))
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(for/fold ([s state]) ([changed routes])
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(if (= (route-level changed) expected-change-level)
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(match (intersect-routes (list changed) (list relevant-change-detector))
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['() s]
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[(list relevant-changed-route) ;; narrowed to relevancy by intersect-routes
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;; (log-info "incorporate-delta ~v ~v <--> ~v /// ~v"
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;; arrivals?
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;; relevant-changed-route
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;; relevant-change-detector
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;; (demand-matcher-state d))
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(define peer-detector
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(struct-copy route relevant-changed-route [level (+ 1 expected-peer-level)]))
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(define peer-exists?
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(ormap (lambda (r) (= (route-level r) expected-peer-level))
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(intersect-routes (presence-detector-routes (demand-matcher-state d))
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(list peer-detector))))
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;; (log-info "peer-exists? == ~v, peer-detector == ~v"
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;; peer-exists?
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;; peer-detector)
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(cond
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[(and arrivals? (not peer-exists?))
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((demand-matcher-increase-handler d) relevant-changed-route s)]
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[(and (not arrivals?) peer-exists?)
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((demand-matcher-decrease-handler d) relevant-changed-route s)]
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[else
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s])])
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s)))
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2013-10-26 18:14:11 +00:00
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(define (demand-matcher-update d state0 rs)
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(define-values (new-state added removed) (presence-detector-update (demand-matcher-state d) rs))
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(define new-d (struct-copy demand-matcher d [state new-state]))
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(define state1 (incorporate-delta #t added new-d state0))
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(define state2 (incorporate-delta #f removed new-d state1))
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(values new-d state2))
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(define (demand-matcher-handle-event e d)
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(match e
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[(routing-update routes)
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(define-values (new-d actions) (demand-matcher-update d '() routes))
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(transition new-d actions)]
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[_ #f]))
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(define (spawn-demand-matcher pattern
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increase-handler
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[decrease-handler unexpected-supply-decrease]
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#:demand-is-subscription? [demand-is-subscription? #t]
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#:meta-level [meta-level 0]
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2013-10-29 15:41:02 +00:00
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#:demand-level [demand-level 0]
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#:supply-level [supply-level 0])
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2013-10-28 19:08:24 +00:00
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(define d (make-demand-matcher demand-is-subscription?
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pattern
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meta-level
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demand-level
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supply-level
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(lambda (r actions) (cons (increase-handler r) actions))
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(lambda (r actions) (cons (decrease-handler r) actions))))
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(spawn demand-matcher-handle-event
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d
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(list (compute-detector #t d)
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(compute-detector #f d))))
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