;; RUN: wast --assert default --snapshot tests/snapshots % -f stack-switching
;; Actors via lightweight threads
;; actor interface
(module $actor
(type $func (func)) ;; [] -> []
(type $cont (cont $func)) ;; cont ([] -> [])
;; self : [i32] -> []
;; spawn : [cont ([] -> [])] -> [i32]
;; send : [i32 i32] -> []
;; recv : [] -> [i32]
(tag $self (export "self") (result i32))
(tag $spawn (export "spawn") (param (ref $cont)) (result i32))
(tag $send (export "send") (param i32 i32))
(tag $recv (export "recv") (result i32))
)
(register "actor")
;; a simple example - pass a message through a chain of actors
(module $chain
(type $func (func)) ;; [] -> []
(type $cont (cont $func)) ;; cont ([] -> [])
(type $i-func (func (param i32))) ;; [i32] -> []
(type $i-cont (cont $i-func)) ;; cont ([i32] -> [])
;; self : [i32] -> []
;; spawn : [cont ([] -> [])] -> [i32]
;; send : [i32 i32] -> []
;; recv : [] -> [i32]
(tag $self (import "actor" "self") (result i32))
(tag $spawn (import "actor" "spawn") (param (ref $cont)) (result i32))
(tag $send (import "actor" "send") (param i32 i32))
(tag $recv (import "actor" "recv") (result i32))
(elem declare func $next)
(func $log (import "spectest" "print_i32") (param i32))
(func $next (param $p i32)
(local $s i32)
(local.set $s (suspend $recv))
(call $log (i32.const -1))
(suspend $send (local.get $s) (local.get $p))
)
;; send the message 42 through a chain of n actors
(func $chain (export "chain") (param $n i32)
(local $p i32)
(local.set $p (suspend $self))
(loop $l
(if (i32.eqz (local.get $n))
(then (suspend $send (i32.const 42) (local.get $p)))
(else (local.set $p (suspend $spawn (cont.bind $i-cont $cont (local.get $p) (cont.new $i-cont (ref.func $next)))))
(local.set $n (i32.sub (local.get $n) (i32.const 1)))
(br $l))
)
)
(call $log (suspend $recv))
)
)
(register "chain")
;; interface to lightweight threads
(module $lwt
(type $func (func))
(type $cont (cont $func))
(tag $yield (export "yield"))
(tag $fork (export "fork") (param (ref $cont)))
)
(register "lwt")
;; queue of threads
(module $queue
(type $func (func))
(type $cont (cont $func))
;; Table as simple queue (keeping it simple, no ring buffer)
(table $queue 0 (ref null $cont))
(global $qdelta i32 (i32.const 10))
(global $qback (mut i32) (i32.const 0))
(global $qfront (mut i32) (i32.const 0))
(func $queue-empty (export "queue-empty") (result i32)
(i32.eq (global.get $qfront) (global.get $qback))
)
(func $dequeue (export "dequeue") (result (ref null $cont))
(local $i i32)
(if (call $queue-empty)
(then (return (ref.null $cont)))
)
(local.set $i (global.get $qfront))
(global.set $qfront (i32.add (local.get $i) (i32.const 1)))
(table.get $queue (local.get $i))
)
(func $enqueue (export "enqueue") (param $k (ref $cont))
;; Check if queue is full
(if (i32.eq (global.get $qback) (table.size $queue))
(then
;; Check if there is enough space in the front to compact
(if (i32.lt_u (global.get $qfront) (global.get $qdelta))
(then
;; Space is below threshold, grow table instead
(drop (table.grow $queue (ref.null $cont) (global.get $qdelta)))
)
(else
;; Enough space, move entries up to head of table
(global.set $qback (i32.sub (global.get $qback) (global.get $qfront)))
(table.copy $queue $queue
(i32.const 0) ;; dest = new front = 0
(global.get $qfront) ;; src = old front
(global.get $qback) ;; len = new back = old back - old front
)
(table.fill $queue ;; null out old entries to avoid leaks
(global.get $qback) ;; start = new back
(ref.null $cont) ;; init value
(global.get $qfront) ;; len = old front = old front - new front
)
(global.set $qfront (i32.const 0))
)
)
)
)
(table.set $queue (global.get $qback) (local.get $k))
(global.set $qback (i32.add (global.get $qback) (i32.const 1)))
)
)
(register "queue")
;; simple scheduler for lightweight threads
(module $scheduler
(type $func (func))
(type $cont (cont $func))
(tag $yield (import "lwt" "yield"))
(tag $fork (import "lwt" "fork") (param (ref $cont)))
(func $queue-empty (import "queue" "queue-empty") (result i32))
(func $dequeue (import "queue" "dequeue") (result (ref null $cont)))
(func $enqueue (import "queue" "enqueue") (param $k (ref $cont)))
(func $run (export "run") (param $main (ref $cont))
(call $enqueue (local.get $main))
(loop $l
(if (call $queue-empty) (then (return)))
(block $on_yield (result (ref $cont))
(block $on_fork (result (ref $cont) (ref $cont))
(resume $cont (on $yield $on_yield) (on $fork $on_fork)
(call $dequeue)
)
(br $l) ;; thread terminated
) ;; $on_fork (result (ref $cont) (ref $cont))
(call $enqueue) ;; current thread
(call $enqueue) ;; new thread
(br $l)
)
;; $on_yield (result (ref $cont))
(call $enqueue) ;; current thread
(br $l)
)
)
)
(register "scheduler")
(module $mailboxes
;; Stupid implementation of mailboxes that raises an exception if
;; there are too many mailboxes or if more than one message is sent
;; to any given mailbox.
;;
;; Sufficient for the simple chain example.
;; -1 means empty
(tag $too-many-mailboxes)
(tag $too-many-messages)
(memory 1)
(global $msize (mut i32) (i32.const 0))
(global $mmax i32 (i32.const 1024)) ;; maximum number of mailboxes
(func $init (export "init")
(memory.fill (i32.const 0) (i32.const -1) (i32.mul (global.get $mmax) (i32.const 4)))
)
(func $empty-mb (export "empty-mb") (param $mb i32) (result i32)
(local $offset i32)
(local.set $offset (i32.mul (local.get $mb) (i32.const 4)))
(i32.eq (i32.load (local.get $offset)) (i32.const -1))
)
(func $new-mb (export "new-mb") (result i32)
(local $mb i32)
(if (i32.ge_u (global.get $msize) (global.get $mmax))
(then (throw $too-many-mailboxes))
)
(local.set $mb (global.get $msize))
(global.set $msize (i32.add (global.get $msize) (i32.const 1)))
(return (local.get $mb))
)
(func $send-to-mb (export "send-to-mb") (param $v i32) (param $mb i32)
(local $offset i32)
(local.set $offset (i32.mul (local.get $mb) (i32.const 4)))
(if (call $empty-mb (local.get $mb))
(then (i32.store (local.get $offset) (local.get $v)))
(else (throw $too-many-messages))
)
)
(func $recv-from-mb (export "recv-from-mb") (param $mb i32) (result i32)
(local $v i32)
(local $offset i32)
(local.set $offset (i32.mul (local.get $mb) (i32.const 4)))
(local.set $v (i32.load (local.get $offset)))
(i32.store (local.get $offset) (i32.const -1))
(local.get $v)
)
)
(register "mailboxes")
;; actors implemented via lightweight threads
(module $actor-as-lwt
(type $func (func)) ;; [] -> []
(type $cont (cont $func)) ;; cont ([] -> [])
(type $i-func (func (param i32))) ;; [i32] -> []
(type $i-cont (cont $i-func)) ;; cont ([i32] -> [])
(type $ic-func (func (param i32 (ref $cont)))) ;; [i32 (cont ([] -> []))] -> []
(type $ic-cont (cont $ic-func)) ;; cont ([i32 (cont ([] -> []))] -> [])
(func $log (import "spectest" "print_i32") (param i32))
;; lwt interface
(tag $yield (import "lwt" "yield"))
(tag $fork (import "lwt" "fork") (param (ref $cont)))
;; mailbox interface
(func $init (import "mailboxes" "init"))
(func $empty-mb (import "mailboxes" "empty-mb") (param $mb i32) (result i32))
(func $new-mb (import "mailboxes" "new-mb") (result i32))
(func $send-to-mb (import "mailboxes" "send-to-mb") (param $v i32) (param $mb i32))
(func $recv-from-mb (import "mailboxes" "recv-from-mb") (param $mb i32) (result i32))
;; queue interface
(func $queue-empty (import "queue" "queue-empty") (result i32))
(func $dequeue (import "queue" "dequeue") (result (ref null $cont)))
(func $enqueue (import "queue" "enqueue") (param $k (ref $cont)))
;; actor interface
;; self : [i32] -> []
;; spawn : [cont ([] -> [])] -> [i32]
;; send : [i32 i32] -> []
;; recv : [] -> [i32]
(tag $self (import "actor" "self") (result i32))
(tag $spawn (import "actor" "spawn") (param (ref $cont)) (result i32))
(tag $send (import "actor" "send") (param i32 i32))
(tag $recv (import "actor" "recv") (result i32))
(elem declare func $actk)
(func $actk (param $mine i32) (param $nextk (ref $cont))
(local $ik (ref $i-cont))
(local $k (ref $cont))
(local $you (ref $cont))
(local $yours i32)
(loop $l
(block $on_self (result (ref $i-cont))
(block $on_spawn (result (ref $cont) (ref $i-cont))
(block $on_send (result i32 i32 (ref $cont))
(block $on_recv (result (ref $i-cont))
(resume $cont (on $self $on_self)
(on $spawn $on_spawn)
(on $send $on_send)
(on $recv $on_recv)
(local.get $nextk)
)
(return)
) ;; $on_recv (result (ref $i-cont))
(local.set $ik)
;; block this thread until the mailbox is non-empty
(loop $blocked
(if (call $empty-mb (local.get $mine))
(then (suspend $yield)
(br $blocked))
)
)
(local.set $nextk (cont.bind $i-cont $cont (call $recv-from-mb (local.get $mine)) (local.get $ik)))
(br $l)
) ;; $on_send (result i32 i32 (ref $cont))
(local.set $k)
(call $send-to-mb)
(local.set $nextk (local.get $k))
(br $l)
) ;; $on_spawn (result (ref $cont) (ref $i-cont))
(local.set $ik)
(local.set $you)
(call $new-mb)
(local.set $yours)
(suspend $fork (cont.bind $ic-cont $cont
(local.get $yours)
(local.get $you)
(cont.new $ic-cont (ref.func $actk))))
(local.set $nextk (cont.bind $i-cont $cont (local.get $yours) (local.get $ik)))
(br $l)
) ;; $on_self (result (ref $i-cont))
(local.set $ik)
(local.set $nextk (cont.bind $i-cont $cont (local.get $mine) (local.get $ik)))
(br $l)
)
)
(func $act (export "act") (param $k (ref $cont))
(call $init)
(call $actk (call $new-mb) (local.get $k))
)
)
(register "actor-as-lwt")
;; composing the actor and scheduler handlers together
(module $actor-scheduler
(type $func (func)) ;; [] -> []
(type $cont (cont $func)) ;; cont ([] -> [])
(type $cont-func (func (param (ref $cont)))) ;; [cont ([] -> []) -> []]
(type $cont-cont (cont $cont-func)) ;; cont ([cont ([] -> []) -> []])
(elem declare func $act $scheduler)
(func $act (import "actor-as-lwt" "act") (param $k (ref $cont)))
(func $scheduler (import "scheduler" "run") (param $k (ref $cont)))
(func $run-actor (export "run-actor") (param $k (ref $cont))
(call $scheduler (cont.bind $cont-cont $cont (local.get $k) (cont.new $cont-cont (ref.func $act))))
)
)
(register "actor-scheduler")
(module
(type $func (func)) ;; [] -> []
(type $cont (cont $func)) ;; cont ([] -> [])
(type $i-func (func (param i32))) ;; [i32] -> []
(type $i-cont (cont $i-func)) ;; cont ([i32] -> [])
(elem declare func $chain)
(func $run-actor (import "actor-scheduler" "run-actor") (param $k (ref $cont)))
(func $chain (import "chain" "chain") (param $n i32))
(func $run-chain (export "run-chain") (param $n i32)
(call $run-actor (cont.bind $i-cont $cont (local.get $n) (cont.new $i-cont (ref.func $chain))))
)
)
(invoke "run-chain" (i32.const 64))