Much simpler, avoiding premature optimisation. Almost ready to try out
This commit is contained in:
Tony Garnock-Jones
parent
84c633dc5c
commit
244055fffb
381
os2.rkt
381
os2.rkt
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@ -1,8 +1,8 @@
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#lang racket/base
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;; Virtualized operating system, this time with presence.
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(require racket/set)
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(require racket/match)
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(require "relation.rkt")
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(require "unify.rkt")
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;; Endpoints are the units of deduplication.
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@ -18,19 +18,21 @@
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;; it's a list of two elements, the first being the endpoint's
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;; process's PID and the second being an integer.
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;; One endpoint, one topic.
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;; A Flow is a Topic that comes from the intersection of two dual
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;; topics.
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;; A QuasiQueue<X> is a list of Xs in *reversed* order.
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(struct vm (processes ;; Hash<PID, Process>
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endpoints ;; Hash<EID, Endpoint>
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topic-flows ;; Relation<Topic, Flow>
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flow-topics ;; Relation<Flow, Topic>
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active-handlers ;; Relation<Topic, Endpoint>
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next-process-id ;; PID
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pending-actions ;; QuasiQueue<(cons PID Action)>
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) #:transparent)
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(struct endpoint (id ;; EID
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topic ;; Topic
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handlers ;; Handlers
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) #:transparent)
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@ -42,21 +44,21 @@
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(struct topic (role pattern virtual?) #:prefab)
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;; A Flow is a Topic that comes from the intersection of two dual
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;; topics.
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;; InterruptK = State -> Transition
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;; PresenceHandler = EID * Topic -> InterruptK
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;; AbsenceHandler = EID * Topic * Reason -> InterruptK
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;; MessageHandler = EID * Topic * Message -> InterruptK
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;; TrapK<X> = X -> InterruptK
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;; PresenceHandler = TrapK<EID * Topic>
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;; AbsenceHandler = TrapK<EID * Topic * Reason>
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;; MessageHandler = TrapK<EID * Topic * Message>
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(struct handlers (presence absence message) #:transparent)
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;; actions is a plain old List<Action>, not a QuasiQueue.
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(struct transition (state actions) #:transparent)
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;; Preactions.
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;; Ks are various TrapKs or #f, signifying lack of interest.
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(struct add-role (topic handlers k) #:prefab)
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(struct delete-role (eid) #:prefab)
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(struct delete-role (eid reason) #:prefab)
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(struct send-message (topic body) #:prefab)
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(struct spawn (thunk k) #:prefab)
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@ -79,8 +81,8 @@
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[else #f]))
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(define (co-topics t)
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(for/list ([role (co-roles (topic-role t))])
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(struct-copy topic t [topic-role role])))
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(for/list ([co-role (co-roles (topic-role t))])
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(struct-copy topic t [role co-role])))
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(define (refine-topic remote-topic new-pattern)
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(struct-copy topic remote-topic [pattern new-pattern]))
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@ -93,14 +95,6 @@
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(and (roles-intersect? (topic-role left) (topic-role right))
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(mgu-canonical (freshen (topic-pattern left)) (freshen (topic-pattern right)))))
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;; True iff the flow between remote-topic and local-topic should be
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;; visible to the local peer. This is the case when either local-topic
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;; is virtual (in which case everything is seen) or otherwise if
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;; remote-topic is also not virtual.
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(define (flow-visible? local-topic remote-topic)
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(or (topic-virtual? local-topic)
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(not (topic-virtual? remote-topic))))
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;;---------------------------------------------------------------------------
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;; QuasiQueue<X>
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@ -126,11 +120,9 @@
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(define (make-vm boot)
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(vm (hash)
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(relation)
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(relation)
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(relation)
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(hash)
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0
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(list->quasi-queue (list (spawn boot)))))
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(list->quasi-queue (list (spawn boot #f)))))
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(define (run-vm state)
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(let loop ((remaining-actions (quasi-queue->list (vm-pending-actions state)))
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@ -152,265 +144,122 @@
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(define (perform-action pid action state)
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(match action
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[(add-role eid topic handlers) (do-subscribe pid eid topic handlers state)]
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[(delete-roles eid) (do-unsubscribe pid eid state)]
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[(add-role topic handlers k) (do-subscribe pid topic handlers k state)]
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[(delete-role eid reason) (do-unsubscribe pid eid reason state)]
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[(send-message topic body) (route-and-deliver topic body state)]
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[(spawn thunk) (do-spawn thunk state)]))
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[(spawn thunk k) (do-spawn pid thunk k state)]))
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(define (install-flow state0 source-flow target-topic)
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(define state
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(struct-copy vm state0
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[topic-flows (relation-add (vm-topic-flows state0) target-topic source-flow)]
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[flow-topics (relation-add (vm-flow-topics state0) source-flow target-topic)]))
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(if (and (flow-visible? target-topic source-flow)
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;; Only notify if not previously notified, i.e., the routes were
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;; absent in state0.
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(not (relation-domain-member? (vm-flow-topics state0) source-flow)))
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(for/fold ([state state])
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([e (in-set (relation-ref (vm-active-handlers state) target-topic))])
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(run-ready state
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(endpoint-process-id e)
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((handlers-presence (endpoint-handlers e)) source-flow)))
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state))
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(define (do-subscribe pid topic handlers k state)
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(define old-process (hash-ref (vm-processes state) pid))
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(define eid-number (process-next-endpoint-id-number old-process))
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(define new-eid (list pid eid-number))
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(struct-copy vm (for*/fold ([state (run-trapk state pid k new-eid)])
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([(matching-pid p) (in-hash (vm-processes state))]
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[matching-eid (in-set (process-endpoints p))]
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[e (in-value (hash-ref (vm-endpoints state) matching-eid))]
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[matching-topic (in-value (endpoint-topic e))]
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[flow-pattern (in-value (topic-intersection topic matching-topic))]
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#:when flow-pattern)
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(define inbound-flow (refine-topic matching-topic flow-pattern))
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(define outbound-flow (refine-topic topic flow-pattern))
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(let* ((state (run-trapk state
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pid
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(handlers-presence handlers)
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new-eid
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inbound-flow))
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(state (run-trapk state
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matching-pid
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(handlers-presence (endpoint-handlers e))
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matching-eid
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outbound-flow)))
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state))
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[processes (hash-set (vm-processes state)
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pid
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(struct-copy process old-process
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[next-endpoint-id-number (+ eid-number 1)]
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[endpoints
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(set-add (process-endpoints old-process)
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new-eid)]))]
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[endpoints (hash-set (vm-endpoints state)
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new-eid
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(endpoint new-eid
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topic
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handlers))]))
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(define ((add-interest eid topic) p)
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(struct-copy process p [interests (relation-add (process-interests p) eid topic)]))
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(define (do-subscribe pid eid topic handlers state)
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(define e (endpoint pid eid handlers))
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(define topic-previously-known? (relation-domain-member? (vm-active-handlers state)))
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;; Install the handler.
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;; Update the process.
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(let ((state
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(struct-copy vm state
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[active-handlers (relation-add (vm-active-handlers state) topic e)]
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[processes (hash-update (vm-processes state) pid (add-interest eid topic))])))
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;; Add topic <--> flow mappings and fire the appropriate presence handlers.
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(if topic-previously-known?
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;; Just tell the local end. The other ends have already heard about this topic.
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(for/fold ([state state])
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([matching-flow (in-set (relation-ref (vm-topic-flows state) topic))])
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(install-flow state matching-flow topic))
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;; Compute intersections, and tell both ends.
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(for/fold ([state state])
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([matching-topic (in-set (vm-known-topics state))]
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[flow-pattern (in-value (topic-intersection topic matching-topic))]
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#:when flow-pattern) ;; We know that topic intersects matching-topic.
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(let* ((state (install-flow state (refine-topic topic flow-pattern) matching-topic))
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(state (install-flow state (refine-topic matching-topic flow-pattern) topic)))
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state)))))
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(define (do-unsubscribe pid eid state)
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;; For each topic in the process's interests,
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;; - for each appropriate endpoint in active-handlers,
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;; - fire the absence handler
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;; - remove the endpoint
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;; - if no handlers remain in active-handlers for that topic,
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;; - for each flow in topic-flows for the topic,
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;; - remove the topic from flow-topics for the flow
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;; - if no topics remain for the flow,
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;; - dualize it using our source topic
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;; - remember it may have virtual duals ???
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;; - for each dual,
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;; - if it has NONE of its own duals left,
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;; -
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;; OK at this point this is getting far too complex.
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;; Back to TSTTCPW: O(n^2) full-table-scans.
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(define (do-unsubscribe pid eid reason state)
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(define endpoint-to-remove (hash-ref (vm-endpoints state) eid))
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(define removed-topic (endpoint-topic endpoint-to-remove))
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(define old-process (hash-ref (vm-processes state) pid))
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(define new-process (struct-copy process old-process
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[endpoints (set-remove (process-endpoints old-process) eid)]))
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(let ((state (struct-copy vm state
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[endpoints (hash-remove (vm-endpoints state) eid)]
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[processes (if (set-empty? (process-endpoints new-process))
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(hash-remove (vm-processes state) pid)
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(hash-set (vm-processes state) pid new-process))])))
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(for*/fold ([state state])
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([(matching-pid p) (in-hash (vm-processes state))]
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[matching-eid (in-set (process-endpoints p))]
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[e (in-value (hash-ref (vm-endpoints state) matching-eid))]
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[matching-topic (in-value (endpoint-topic e))]
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[flow-pattern (in-value (topic-intersection removed-topic matching-topic))]
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#:when flow-pattern)
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(define outbound-flow (refine-topic removed-topic flow-pattern))
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(run-trapk state
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matching-pid
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(handlers-absence (endpoint-handlers e))
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matching-eid
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outbound-flow
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reason))))
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(define (route-and-deliver message-topic body state)
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(define endpoints
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(for/set ([flow (in-relation-domain (vm-flow-topics state))]
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#:when (specialization? message-topic flow)
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[matching-flow (co-topics flow)]
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[matching-topic (in-set (relation-ref (vm-flow-topics state) matching-flow))]
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[matching-endpoint (in-set (relation-ref (vm-active-handlers state) matching-topic))])
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matching-endpoint))
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(for/fold ([state state]) ([e (in-set endpoints)])
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(run-ready state
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(endpoint-process-id e)
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((handlers-message (endpoint-handlers e)) message-topic body))))
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(define pids-and-endpoints
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(for*/set ([(matching-pid p) (in-hash (vm-processes state))]
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[matching-eid (in-set (process-endpoints p))]
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[e (in-value (hash-ref (vm-endpoints state) matching-eid))]
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[matching-topic (in-value (endpoint-topic e))]
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[flow-pattern (in-value (topic-intersection message-topic matching-topic))]
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#:when flow-pattern)
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(cons matching-pid e)))
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(for/fold ([state state]) ([pid-and-endpoint (in-set pids-and-endpoints)])
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(define matching-pid (car pid-and-endpoint))
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(define e (cdr pid-and-endpoint))
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(run-trapk state
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matching-pid
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(handlers-message (endpoint-handlers e))
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(endpoint-id e)
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message-topic
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body)))
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(define (run-trapk state pid trap-k . args)
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(run-ready state pid (run-user-code (apply trap-k args))))
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(define (run-ready state pid interrupt-k)
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(define old-process (hash-ref (vm-processes state) pid))
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(match-define (transition new-process-state actions)
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(interrupt-k (process-state old-process-state)))
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(run-user-code (interrupt-k (process-state old-process))))
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(struct-copy vm (enqueue-actions state pid actions)
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[processes (hash-set (vm-processes state) pid
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(struct-copy process old-process
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[state new-process-state]))]))
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(define (do-spawn thunk state)
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(define (do-spawn spawning-pid thunk k state)
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(match-define (transition initial-state initial-actions) (run-user-code (thunk)))
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(define new-pid (vm-next-process-id state))
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(struct-copy vm (enqueue-actions state new-pid initial-actions)
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[processes (hash-set (vm-processes state) new-pid (process new-pid
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initial-state
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(relation)
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(relation)))]
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[next-process-id (+ new-pid 1)]))
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(run-trapk (struct-copy vm (enqueue-actions state new-pid initial-actions)
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[processes (hash-set (vm-processes state) new-pid (process new-pid
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initial-state
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0
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(set)))]
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[next-process-id (+ new-pid 1)])
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spawning-pid
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k
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new-pid))
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(define (enqueue-actions state pid actions)
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(struct-copy vm state
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[pending-actions (quasi-enqueue-many (for/list ([a actions]) (cons pid a))
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(vm-pending-actions state))]))
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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(let* ((state (requeue-pollers state))
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(state (run-runnables state))
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(state (dispatch-messages state))
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(meta-messages (reverse (vm-pending-meta-messages state)))
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(meta-handlers (append-map extract-downward-meta-message-handlers (vm-suspensions state)))
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(poller-k (and (should-poll? state) run-vm)) ;; only block if there's nothing left to do
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(state (struct-copy vm state [pending-meta-messages (list)])))
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(kernel-mode-transition (suspension state poller-k meta-handlers '())
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meta-messages
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'()
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'())))
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(define (requeue-pollers state)
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(foldl (lambda (susp state)
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(if (suspension-polling? susp)
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(enqueue-runnable (lambda () ((suspension-k susp) (suspension-state susp))) state)
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(enqueue-suspension susp state)))
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(struct-copy vm state [suspensions '()])
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(vm-suspensions state)))
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(define (run-runnables state)
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(foldl (lambda (r state) (perform-transition (r) state))
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(struct-copy vm state [pending-processes (list)])
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(reverse (vm-pending-processes state))))
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(define (dispatch-messages state)
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(foldl dispatch-message
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(struct-copy vm state [pending-messages (list)])
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(reverse (vm-pending-messages state))))
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(define (extract-downward-meta-message-handlers susp)
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(for/list ([mmh (suspension-meta-message-handlers susp)])
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(message-handler (message-handler-pattern mmh) dispatch-meta-message)))
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(define ((dispatch-meta-message message) state)
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(run-vm
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(foldl (match-suspension message
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(vm-meta-pattern-predicate state)
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suspension-meta-message-handlers)
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(struct-copy vm state [suspensions '()])
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(vm-suspensions state))))
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(define (perform-transition transition state)
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(match transition
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[(kernel-mode-transition new-suspension
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messages
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meta-messages
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new-processes)
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(let* ((state (foldl enqueue-message state messages))
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(state (foldl enqueue-runnable state new-processes))
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(state (enqueue-suspension new-suspension state))
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(state (foldl enqueue-meta-message state meta-messages)))
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state)]
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[other
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(error 'vm "Processes must return a kernel-mode-transition struct; got ~v" other)]))
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(define (enqueue-message message state)
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(struct-copy vm state [pending-messages (cons message (vm-pending-messages state))]))
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(define (enqueue-runnable r state)
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(struct-copy vm state [pending-processes (cons r (vm-pending-processes state))]))
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(define (enqueue-suspension susp state)
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(match susp
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[(suspension _ #f '() '())
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;; dead process because no continuations offered
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state]
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[(suspension _ _ _ _)
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(struct-copy vm state [suspensions (cons susp (vm-suspensions state))])]))
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(define (enqueue-meta-message message state)
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(struct-copy vm state [pending-meta-messages (cons message (vm-pending-meta-messages state))]))
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(define (dispatch-message message state)
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(foldl (match-suspension message
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(vm-pattern-predicate state)
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suspension-message-handlers)
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(struct-copy vm state [suspensions '()])
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(vm-suspensions state)))
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(define ((match-suspension message apply-pattern handlers-getter) susp state)
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(let search-handlers ((message-handlers (handlers-getter susp)))
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(cond
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[(null? message-handlers)
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;; No handler matched this message. Put the suspension
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;; back on the list for some future message.
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(enqueue-suspension susp state)]
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[(apply-pattern (message-handler-pattern (car message-handlers)) message)
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(define trapk (message-handler-k (car message-handlers)))
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(define interruptk (trapk message))
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(perform-transition (interruptk (suspension-state susp)) state)]
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[else
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(search-handlers (cdr message-handlers))])))
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(define (suspension-polling? susp)
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(not (eq? (suspension-k susp) #f)))
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(define (should-poll? state)
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(or (not (null? (vm-pending-processes state)))
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(not (null? (vm-pending-messages state)))
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(ormap suspension-polling? (vm-suspensions state))))
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(define (nested-vm boot
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#:pattern-predicate [pattern-predicate default-pattern-predicate]
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#:meta-pattern-predicate [meta-pattern-predicate default-pattern-predicate])
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(lambda () (run-vm (make-vm boot
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#:pattern-predicate pattern-predicate
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#:meta-pattern-predicate meta-pattern-predicate))))
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(define default-pattern-predicate
|
||||
(lambda (p m) (p m)))
|
||||
|
||||
;;---------------------------------------------------------------------------
|
||||
|
||||
(define (nested-vm-inert? susp)
|
||||
(match susp
|
||||
[(suspension (vm _ '() '() '() _ _) #f '() '())
|
||||
;; Inert iff not waiting for any messages or metamessages, and
|
||||
;; with no internal work left to do.
|
||||
#t]
|
||||
[_ #f]))
|
||||
|
||||
(struct ground-event-pattern (tag evt) #:transparent)
|
||||
(struct ground-event-value (tag val) #:transparent)
|
||||
|
||||
(define (match-ground-event p m)
|
||||
(equal? (ground-event-pattern-tag p) (ground-event-value-tag m)))
|
||||
|
||||
(define (ground-vm boot
|
||||
#:pattern-predicate [pattern-predicate default-pattern-predicate])
|
||||
(let loop ((transition (run-vm (make-vm boot
|
||||
#:pattern-predicate pattern-predicate
|
||||
#:meta-pattern-predicate match-ground-event))))
|
||||
(for-each (lambda (thunk) (thunk)) (kernel-mode-transition-messages transition))
|
||||
(when (not (nested-vm-inert? (kernel-mode-transition-suspension transition)))
|
||||
(match transition
|
||||
[(kernel-mode-transition (suspension new-state
|
||||
polling-k
|
||||
message-handlers
|
||||
'())
|
||||
_
|
||||
'()
|
||||
'())
|
||||
(define inbound-messages
|
||||
(map (match-lambda [(message-handler (ground-event-pattern tag evt) k)
|
||||
(wrap-evt evt (lambda (v) (cons (ground-event-value tag v) k)))])
|
||||
message-handlers))
|
||||
(match-define (cons inbound-value inbound-continuation)
|
||||
(apply sync
|
||||
(wrap-evt (if polling-k always-evt never-evt)
|
||||
(lambda (v) (cons (ground-event-value 'idle (void))
|
||||
(lambda (dummy) polling-k))))
|
||||
inbound-messages))
|
||||
(loop ((inbound-continuation inbound-value) new-state))]
|
||||
[_
|
||||
(error 'ground-vm
|
||||
"Outermost VM may not spawn new siblings or send or receive metamessages")]))))
|
||||
(define (perform-meta-action pid preaction state)
|
||||
(error 'perform-meta-action "%%% Not implemented"))
|
||||
|
|
|
|||
Loading…
Reference in New Issue