119 lines
4.6 KiB
Racket
119 lines
4.6 KiB
Racket
#lang racket/base
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;; General multiplexer.
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(provide meta-label?
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(except-out (struct-out mux) mux)
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(rename-out [mux <mux>] [make-mux mux])
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mux-add-stream
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mux-remove-stream
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mux-update-stream
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mux-route-message
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mux-interests-of
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echo-cancelled-routing-table
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compute-scns
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compute-affected-pids
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pretty-print-mux)
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(require racket/set)
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(require racket/match)
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(require "../syndicate/trie.rkt")
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(require "scn.rkt")
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(require "../syndicate/trace.rkt")
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(require "../syndicate/tset.rkt")
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(require "../syndicate/pretty.rkt")
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;; A PID is a Nat.
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;; A Label is a PID or 'meta.
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;; Multiplexer private states
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(struct mux (next-pid ;; PID
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routing-table ;; (Matcherof (Setof Label))
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interest-table ;; (HashTable Label Matcher)
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)
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#:transparent
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#:methods gen:syndicate-pretty-printable
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[(define (syndicate-pretty-print m [p (current-output-port)])
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(pretty-print-mux m p))])
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (meta-label? x) (eq? x 'meta))
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(define (make-mux)
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(mux 0 trie-empty (hash)))
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(define (mux-add-stream m initial-scn)
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(define new-pid (mux-next-pid m))
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(mux-update-stream (struct-copy mux m [next-pid (+ new-pid 1)])
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new-pid
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initial-scn))
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(define (mux-remove-stream m label)
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(mux-update-stream m label (scn trie-empty)))
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(define (mux-update-stream m label new-scn)
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(define old-interests (mux-interests-of m label))
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(define old-routing-table (mux-routing-table m))
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(define new-interests (label-interests (scn-trie new-scn) (datum-tset label)))
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(define new-routing-table (trie-union (trie-subtract old-routing-table old-interests)
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new-interests))
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(define aggregate-assertions (trie-union old-interests new-interests))
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(values (struct-copy mux m
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[routing-table new-routing-table]
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[interest-table (if (trie-empty? new-interests)
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(hash-remove (mux-interest-table m) label)
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(hash-set (mux-interest-table m) label new-interests))])
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label
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new-scn ;; unnecessary?
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aggregate-assertions))
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(define at-meta-everything (pattern->trie '<at-meta-everything> (at-meta ?)))
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(define only-meta (datum-tset 'meta))
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(define (echo-cancelled-routing-table m)
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(trie-subtract (mux-routing-table m)
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at-meta-everything
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#:combiner (lambda (v1 v2)
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(if (tset-member? v1 'meta)
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(trie-success only-meta)
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trie-empty))))
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(define (compute-scns old-m new-m label s aggregate-assertions)
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(define old-routing-table (mux-routing-table old-m))
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(define new-routing-table (mux-routing-table new-m))
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(define echo-cancelled-assertions (echo-cancelled-routing-table new-m))
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(define affected-pids
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(let ((pids (compute-affected-pids old-routing-table aggregate-assertions)))
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(tset-remove (tset-add pids label) 'meta))) ;; TODO: removing meta is weird
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(values (for/list [(pid (tset->list affected-pids))]
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(cons pid (scn (biased-intersection echo-cancelled-assertions
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(mux-interests-of new-m pid)))))
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(and (not (meta-label? label))
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(drop-scn (scn (trie-relabel new-routing-table
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(lambda (v)
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(empty-tset-guard (tset-remove v 'meta)))))))))
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(define (compute-affected-pids routing-table cover)
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(trie-match-trie cover
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(trie-step routing-table observe-parenthesis)
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#:seed datum-tset-empty
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#:combiner (lambda (v1 v2 acc) (tset-union v2 acc))))
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(define (mux-route-message m body)
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(if (trie-lookup (mux-routing-table m) body #f) ;; some other stream has declared body
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'()
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(tset->list (trie-lookup (mux-routing-table m) (observe body) datum-tset-empty))))
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(define (mux-interests-of m label)
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(hash-ref (mux-interest-table m) label trie-empty))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (pretty-print-mux m [p (current-output-port)])
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(match-define (mux next-pid routing-table interest-table) m)
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(fprintf p "MUX:\n")
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(fprintf p " - ~a labelled entities with claims\n" (hash-count interest-table))
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(fprintf p " - next label: ~a\n" next-pid)
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(fprintf p " - routing-table:\n")
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(display (indented-port-output 3 (lambda (p) (pretty-print-trie routing-table p))) p)
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(newline p))
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