runner.bend
bend-kit-runner@0.12.0.0 · 1,785 lines · 0 definitions
1# Durable job runner: a journaled scheduler queue, bounded by a resources pool, with retry and a breaker per target. Source: https://github.com/paymog/bend-kit/tree/main/runner
2import Base
3import bend-kit-bytes@0.3.3.0/bytes.bend as Bytes
4import bend-kit-journal@0.3.0.1/journal.bend as J
5import bend-kit-scheduler@0.4.1.0/queue.bend as Q
6import bend-kit-resources@0.1.0.0/resources.bend as Res
7import bend-kit-retry@0.2.0.0/retry.bend as Retry
8import bend-kit-time@0.3.0.0/time.bend as Time
9import bend-kit-collections@0.1.4.1/heap.bend as H
10import bend-kit-collections@0.1.4.1/omap.bend as O
11import bend-kit-collections@0.1.4.1/hmap.bend as M
12import bend-kit-files@0.3.0.0/files.bend as Files
13
14# Why retry gave up on a ticket: its budget was spent, its deadline passed, its failure must not repeat,
15# or another try would repeat its failure.
16type Why is Data:
17 WhySpent{}
18 WhyLate{}
19 WhyUnsafe{}
20 WhyFailed{}
21
22# A ticket that retry gave up on, with its payload, and when it gave up (wall-clock ms).
23# It stays until Revive, Cancel, or Purge takes it.
24type Dead<-A: Data> is Data:
25 Dead{ticket: Q.Ticket<A>, why: Why, at: Nat}
26
27# One durable transition. Each one is one journal record, appended before the state changes.
28# Select: the queue's select at now. Replay runs it at the same now, so it takes the same ticket.
29# Requeue: the attempt failed; it counts one failure. Defer: the breaker held the ticket back; no attempt ran.
30# Abandon: retry gave up at at; the running ticket becomes dead. Revive: a dead ticket is pending again at deadline, with a new budget.
31# Purge: the dead tickets abandoned before before are dropped. PurgeAll: every dead ticket is dropped.
32# Break: the breaker of target changed to state.
33type Op<-A: Data> is Data:
34 Enqueue{deadline: Nat, payload: A}
35 Select{now: Nat}
36 Complete{id: Nat}
37 Cancel{id: Nat}
38 Requeue{id: Nat, deadline: Nat}
39 Defer{id: Nat, deadline: Nat}
40 Abandon{id: Nat, why: Why, at: Nat}
41 Revive{id: Nat, deadline: Nat}
42 Purge{before: Nat}
43 PurgeAll{}
44 Break{target: String, state: Retry.State}
45
46# The failed attempts of a ticket, and its first deadline, from which the policy deadline counts.
47type Try is Data:
48 Try{fails: Nat, start: Nat}
49
50# A Try for each ticket that is not yet complete, cancelled, or dead, by ticket id.
51def Tries() -> Data:
52 O.OMap<Nat, Try>
53
54# The breaker state of each target that has one, by target. An absent target is closed with no failures.
55def Breakers() -> Data:
56 Map<&2, Retry.State>
57
58def dead.hash(i: Nat) -> U32:
59 U32.from_nat(i)
60
61# The dead tickets, by ticket id.
62def Graves(-A: Data) -> Data:
63 M.HMap<Nat, Dead<A>>
64
65# The durable state: the queue, the tries, the dead tickets, and the breakers.
66type State<-A: Data> is Data:
67 State{queue: Q.State<A>, tries: Tries(), dead: Graves(A), breakers: Breakers()}
68
69def new(-A: Data) -> State<A>:
70 State{Q.new(A), O.OMap.new(Nat, Try), M.HMap.new(Nat, Dead<A>), Map.new(&2, Retry.State)}
71
72def queue(-A: Data, s: State<A>) -> Q.State<A>:
73 State{q, ts, ds, bs} = s
74 q
75
76def tries(-A: Data, s: State<A>) -> Tries():
77 State{q, ts, ds, bs} = s
78 ts
79
80# The dead tickets, by id. A Revive of one makes it pending again; a Cancel or a Purge drops it.
81def dead(-A: Data, s: State<A>) -> Graves(A):
82 State{q, ts, ds, bs} = s
83 ds
84
85def breakers(-A: Data, s: State<A>) -> Breakers():
86 State{q, ts, ds, bs} = s
87 bs
88
89# ---- dead tickets
90
91def dead.get(~A: Data, ds: Graves(A), +i: Nat) -> Maybe<&2, Dead<A>>:
92 M.HMap.get(~Nat, ~Dead<A>, ~dead.hash, ~Nat.is_eq, ds, i)
93
94def dead.drop(~A: Data, ds: Graves(A), +i: Nat) -> Graves(A):
95 M.HMap.del(~Nat, ~Dead<A>, ~dead.hash, ~Nat.is_eq, ds, i)
96
97def dead.bury(~A: Data, m: Maybe<&2, Q.Ticket<A>>, ds: Graves(A), w: Why, +at: Nat) -> Graves(A):
98 match m:
99 case None{}:
100 ds
101 case Some{Q.Ticket{+i, d, x}}:
102 M.HMap.put(~Nat, ~Dead<A>, ~dead.hash, ~Nat.is_eq, ds, i, Dead{Q.Ticket{i, d, x}, w, at})
103
104def dead.list.entries(-A: Data, es: List<&2, M.Entry<Nat, Dead<A>>>, acc: List<&2, Dead<A>>) -> List<&2, Dead<A>>:
105 match es:
106 case Nil{}:
107 acc
108 case Con{M.Entry{k, d}, rest}:
109 dead.list.entries(A, rest, Con{d, acc})
110
111def dead.list.go(-A: Data, ds: Graves(A), acc: List<&2, Dead<A>>) -> List<&2, Dead<A>>:
112 match ds:
113 case M.HNil{}:
114 acc
115 case M.HLeaf{h, es}:
116 dead.list.entries(A, es, acc)
117 case M.HBranch{lo, hi}:
118 dead.list.go(A, lo, dead.list.go(A, hi, acc))
119
120# The dead tickets, in no set order.
121def dead.list(-A: Data, ds: Graves(A)) -> List<&2, Dead<A>>:
122 dead.list.go(A, ds, Nil{})
123
124def dead.old.keep(-A: Data, old: Bool, +i: Nat, rest: List<&2, Nat>) -> List<&2, Nat>:
125 match old:
126 case True{}:
127 Con{i, rest}
128 case False{}:
129 rest
130
131# The ids of the dead tickets abandoned before t.
132def dead.old(-A: Data, ds: List<&2, Dead<A>>, +t: Nat) -> List<&2, Nat>:
133 match ds:
134 case Nil{}:
135 Nil{}
136 case Con{Dead{Q.Ticket{i, d, x}, w, +at}, rest}:
137 dead.old.keep(A, Nat.is_lt(at, t), i, dead.old(A, rest, t))
138
139def dead.drops(~A: Data, ks: List<&2, Nat>, ds: Graves(A)) -> Graves(A):
140 match ks:
141 case Nil{}:
142 ds
143 case Con{k, rest}:
144 dead.drops(~A, rest, dead.drop(~A, ds, k))
145
146# The dead tickets without those abandoned before t. It walks every dead ticket once.
147def dead.purge(~A: Data, +ds: Graves(A), +t: Nat) -> Graves(A):
148 dead.drops(~A, dead.old(A, dead.list(A, ds), t), ds)
149
150# ---- tries
151
152def tries.drop(ts: Tries(), +i: Nat) -> Tries():
153 O.OMap.del(~Nat, ~Try, ~Nat.cmp, ts, i)
154
155def tries.get(ts: Tries(), +i: Nat) -> Maybe<&2, Try>:
156 O.OMap.get(~Nat, ~Try, ~Nat.cmp, ts, i)
157
158def tries.bump.got(m: Maybe<&2, Try>, ts: Tries(), +i: Nat) -> Tries():
159 match m:
160 case None{}:
161 ts
162 case Some{Try{f, st}}:
163 O.OMap.put(~Nat, ~Try, ~Nat.cmp, ts, i, Try{1n+f, st})
164
165def tries.bump(+ts: Tries(), +i: Nat) -> Tries():
166 tries.bump.got(tries.get(ts, i), ts, i)
167
168# ---- breakers
169
170def brk.got(r: Breakers() & Retry.State) -> Retry.State:
171 (m, b) = r
172 b
173
174# The breaker state of target key.
175def brk.get(-A: Data, s: State<A>, key: String) -> Retry.State:
176 brk.got(Map.get(Retry.State, Retry.CircuitClosed{Nil{}}, breakers(A, s), key))
177
178def brk.state(br: Retry.Breaker, old: Retry.State) -> Retry.State:
179 match br:
180 case Retry.BreakerOff{}:
181 old
182 case Retry.BreakerOn{c, st}:
183 st
184
185def brk.nats(a: List<&2, Nat>, b: List<&2, Nat>) -> Bool:
186 match a b:
187 case Nil{} Nil{}:
188 True{}
189 case Con{+x, xs} Con{+y, ys}:
190 Bool.and(Nat.is_eq(x, y), brk.nats(xs, ys))
191 case p q:
192 False{}
193
194def brk.same(a: Retry.State, b: Retry.State) -> Bool:
195 match a b:
196 case Retry.CircuitClosed{xs} Retry.CircuitClosed{ys}:
197 brk.nats(xs, ys)
198 case Retry.CircuitOpen{+x} Retry.CircuitOpen{+y}:
199 Nat.is_eq(x, y)
200 case Retry.CircuitHalf{+x} Retry.CircuitHalf{+y}:
201 Nat.is_eq(x, y)
202 case p q:
203 False{}
204
205def calm.state(b: Retry.State) -> Retry.State:
206 match b:
207 case Retry.CircuitClosed{fs}:
208 Retry.CircuitClosed{fs}
209 case Retry.CircuitOpen{u}:
210 Retry.CircuitOpen{u}
211 case Retry.CircuitHalf{k}:
212 Retry.CircuitHalf{0n}
213
214def calm.map(m: Breakers()) -> Breakers():
215 match m:
216 case MTip{}:
217 MTip{}
218 case MLeaf{k, v}:
219 MLeaf{k, calm.state(v)}
220 case MNode{p, lo, hi}:
221 MNode{p, calm.map(lo), calm.map(hi)}
222
223# The probes of a half-open breaker died with the process that ran them, so open counts none in flight.
224def calm(-A: Data, s: State<A>) -> State<A>:
225 State{q, ts, ds, bs} = s
226 State{q, ts, ds, calm.map(bs)}
227
228# ---- the transition
229
230def step.enqueued(-A: Data, r: Q.State<A> & Nat, ts: Tries(), ds: Graves(A), bs: Breakers(), d: Nat) -> State<A>:
231 (q, i) = r
232 State{q, O.OMap.put(~Nat, ~Try, ~Nat.cmp, ts, i, Try{0n, d}), ds, bs}
233
234def step.selected(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, ts: Tries(), ds: Graves(A), bs: Breakers()) -> State<A>:
235 (q, t) = r
236 State{q, ts, ds, bs}
237
238def step.requeued(-A: Data, r: Q.State<A> & Bool, ts: Tries(), ds: Graves(A), bs: Breakers()) -> State<A>:
239 (q, b) = r
240 State{q, ts, ds, bs}
241
242# Complete takes the ticket from the running list only: O(running), not O(pending).
243def step.completed(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, ts: Tries(), ds: Graves(A), bs: Breakers()) -> State<A>:
244 (q, t) = r
245 State{q, ts, ds, bs}
246
247# Abandon takes the ticket from the running list, as Complete does, and keeps it with its payload.
248def step.abandoned(~A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, ts: Tries(), ds: Graves(A), bs: Breakers(), w: Why, +at: Nat) -> State<A>:
249 (q, t) = r
250 State{q, ts, dead.bury(~A, t, ds, w, at), bs}
251
252# The revived ticket keeps its payload and takes id i, the key it was dead under.
253def step.revived(~A: Data, m: Maybe<&2, Dead<A>>, +i: Nat, n: Nat, h: H.Heap<Q.Ticket<A>>, r: List<&2, Q.Ticket<A>>, ts: Tries(), ds: Graves(A), bs: Breakers(), +d: Nat) -> State<A>:
254 match m:
255 case None{}:
256 State{Q.State{n, h, r}, ts, ds, bs}
257 case Some{Dead{Q.Ticket{k, old, x}, w, at}}:
258 State{Q.State{n, H.Heap.push(~Q.Ticket<A>, ~(a => b => Q.le(A, a, b)), Q.Ticket{i, d, x}, h), r}, O.OMap.put(~Nat, ~Try, ~Nat.cmp, ts, i, Try{0n, d}), ds, bs}
259
260# The state after op. Live and replay both run it, so they agree.
261def step(~A: Data, s: State<A>, op: Op<A>) -> State<A>:
262 match s op:
263 case State{q, ts, ds, bs} Enqueue{+d, x}:
264 step.enqueued(A, Q.enqueue(~A, d, x, q), ts, ds, bs, d)
265 case State{q, ts, ds, bs} Select{now}:
266 step.selected(A, Q.select(~A, now, q), ts, ds, bs)
267 case State{q, ts, ds, bs} Complete{+i}:
268 step.completed(A, Q.complete(A, i, q), tries.drop(ts, i), ds, bs)
269 case State{q, ts, ds, bs} Cancel{+i}:
270 State{Q.cancel(~A, i, q), tries.drop(ts, i), dead.drop(~A, ds, i), bs}
271 case State{q, ts, ds, bs} Requeue{+i, d}:
272 step.requeued(A, Q.requeue(~A, i, d, q), tries.bump(ts, i), ds, bs)
273 case State{q, ts, ds, bs} Defer{i, d}:
274 step.requeued(A, Q.requeue(~A, i, d, q), ts, ds, bs)
275 case State{q, ts, ds, bs} Abandon{+i, w, at}:
276 step.abandoned(~A, Q.complete(A, i, q), tries.drop(ts, i), ds, bs, w, at)
277 case State{Q.State{n, h, r}, ts, +ds, bs} Revive{+i, d}:
278 step.revived(~A, dead.get(~A, ds, i), i, n, h, r, ts, dead.drop(~A, ds, i), bs, d)
279 case State{q, ts, ds, bs} Purge{t}:
280 State{q, ts, dead.purge(~A, ds, t), bs}
281 case State{q, ts, ds, bs} PurgeAll{}:
282 State{q, ts, M.HMap.new(Nat, Dead<A>), bs}
283 case State{q, ts, ds, bs} Break{k, b}:
284 State{q, ts, ds, Map.set(&2, Retry.State, bs, k, b)}
285
286def apply.op(~A: Data, m: Maybe<&2, Op<A>>, s: State<A>) -> Maybe<&2, State<A>>:
287 match m:
288 case None{}:
289 None{}
290 case Some{op}:
291 Some{step(~A, s, op)}
292
293# Folds one record into the replayed state. A record that does not decode ends the replay with None.
294def apply(~A: Data, ~R: Type, ~dec: R -> Maybe<&2, Op<A>>, acc: Maybe<&2, State<A>>, r: R) -> Maybe<&2, State<A>>:
295 match acc:
296 case None{}:
297 None{}
298 case Some{s}:
299 apply.op(~A, dec(r), s)
300
301# A journal record. Compaction writes one Snap of the whole state; every other record is one op.
302type Rec<-A: Data> is Data:
303 Snap{state: State<A>}
304 Do{op: Op<A>}
305
306def load.rec(~A: Data, m: Maybe<&2, Rec<A>>, s: State<A>) -> Maybe<&2, State<A>>:
307 match m:
308 case None{}:
309 None{}
310 case Some{Snap{t}}:
311 Some{t}
312 case Some{Do{op}}:
313 Some{step(~A, s, op)}
314
315# Folds one record into the replayed state: a Snap replaces it, and an op steps it, as apply does.
316# A record that does not decode ends the replay with None.
317def load(~A: Data, ~R: Type, ~dec: R -> Maybe<&2, Rec<A>>, acc: Maybe<&2, State<A>>, r: R) -> Maybe<&2, State<A>>:
318 match acc:
319 case None{}:
320 None{}
321 case Some{s}:
322 load.rec(~A, dec(r), s)
323
324# ---- pool
325
326# Picked: a due ticket and one unit of the pool for it. Idle: no due ticket, or no free unit; the pool is unchanged.
327type Pick<-A: Data> is Type:
328 Picked{pool: Res.Pool, ticket: Q.Ticket<A>, grant: Res.Grant}
329 Idle{pool: Res.Pool}
330
331def pick.took(-A: Data, r: Res.Reserve, t: Q.Ticket<A>) -> Pick<A>:
332 match r:
333 case Res.Took{p, g}:
334 Picked{p, t, g}
335 case Res.Refused{p}:
336 Idle{p}
337
338def pick.due(-A: Data, m: Maybe<&2, Q.Ticket<A>>, p: Res.Pool) -> Pick<A>:
339 match m:
340 case None{}:
341 Idle{p}
342 case Some{t}:
343 pick.took(A, Res.reserve(p, 1n), t)
344
345def pick.sel(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, p: Res.Pool) -> Pick<A>:
346 (q, m) = r
347 pick.due(A, m, p)
348
349# The ticket that Select{now} takes, with one unit of p, when there is a ticket due and a unit free.
350def pick(~A: Data, p: Res.Pool, s: State<A>, now: Nat) -> Pick<A>:
351 State{q, ts, ds, bs} = s
352 pick.sel(A, Q.select(~A, now, q), p)
353
354# ---- retry
355
356# The budget left for ticket i: the policy's attempts less its failures, until its start plus the policy deadline.
357def budget.of(+attempts: Nat, t: Maybe<&2, Try>, d: Maybe<&2, Nat>) -> Retry.Budget:
358 match t d:
359 case None{} m:
360 Retry.Budget{attempts, None{}}
361 case Some{Try{f, st}} None{}:
362 Retry.Budget{Nat.sub(attempts, f), None{}}
363 case Some{Try{f, +st}} Some{ms}:
364 Retry.Budget{Nat.sub(attempts, f), Some{Nat.add(st, ms)}}
365
366def budget(p: Retry.Policy, t: Maybe<&2, Try>) -> Retry.Budget:
367 Retry.Policy{a, base, cap, d} = p
368 budget.of(a, t, d)
369
370# The failures so far: the index of the next retry.
371def fails(t: Maybe<&2, Try>) -> Nat:
372 match t:
373 case None{}:
374 0n
375 case Some{Try{f, st}}:
376 f
377
378# Why retry stopped a transient failure: no attempt is left, or the next wait would reach the deadline.
379def gave(b: Retry.Budget) -> Why:
380 Retry.Budget{left, d} = b
381 match left:
382 case 0n:
383 WhySpent{}
384 case 1n+k:
385 WhyLate{}
386
387# A settled attempt completes its ticket; retry gave up at now on any other.
388def stopped(-A: Data, o: Retry.Outcome, b: Retry.Budget, +id: Nat, +now: Nat) -> Op<A>:
389 match o:
390 case Retry.Settled{}:
391 Complete{id}
392 case Retry.Failed{}:
393 Abandon{id, WhyFailed{}, now}
394 case Retry.Unsafe{}:
395 Abandon{id, WhyUnsafe{}, now}
396 case Retry.Transient{w}:
397 Abandon{id, gave(b), now}
398
399def after.plan(-A: Data, pl: Retry.Plan, o: Retry.Outcome, b: Retry.Budget, +id: Nat, +now: Nat) -> Op<A>:
400 match pl:
401 case Retry.PlanStop{}:
402 stopped(A, o, b, id, now)
403 case Retry.PlanWait{w}:
404 Requeue{id, Nat.add(now, w)}
405
406# The record after an attempt of ticket id ends at now with o: requeue at now plus retry's wait,
407# complete when o is settled, or abandon when retry gave up.
408def after(-A: Data, +o: Retry.Outcome, p: Retry.Policy, +b: Retry.Budget, +id: Nat, +n: Nat, +now: Nat, +r: Nat) -> Op<A>:
409 after.plan(A, Retry.plan(o, p, b, n, now, r), o, b, id, now)
410
411# When an open breaker lets attempts start again.
412def until(br: Retry.Breaker, +now: Nat) -> Nat:
413 match br:
414 case Retry.BreakerOn{c, Retry.CircuitOpen{u}}:
415 u
416 case Retry.BreakerOn{c, Retry.CircuitClosed{fs}}:
417 Nat.add(now, Retry.Circuit.cooldown(c))
418 case Retry.BreakerOn{c, Retry.CircuitHalf{k}}:
419 Nat.add(now, Retry.Circuit.cooldown(c))
420 case Retry.BreakerOff{}:
421 now
422
423# The record for a ticket that admit refused: Defer to when the breaker may admit, or Abandon when its budget is spent or late.
424def held(-A: Data, why: Retry.Deny, br: Retry.Breaker, +id: Nat, +now: Nat) -> Op<A>:
425 match why:
426 case Retry.DenyOpen{}:
427 Defer{id, until(br, now)}
428 case Retry.DenyLate{}:
429 Abandon{id, WhyLate{}, now}
430 case Retry.DenySpent{}:
431 Abandon{id, WhySpent{}, now}
432
433# ---- the record codec: a u32le tag, then u64le fields; an Enqueue then holds the payload.
434# An Abandon is tag 8, then id, why.code, and at. A Purge is tag 11 and before; a PurgeAll is tag 12.
435# A Break is tag 10, then its target and its breaker state.
436
437def why.code(w: Why) -> Nat:
438 match w:
439 case WhySpent{}:
440 0n
441 case WhyLate{}:
442 1n
443 case WhyUnsafe{}:
444 2n
445 case WhyFailed{}:
446 3n
447
448def W() -> Nat:
449 Nat.mul(65536n, 65536n)
450
451# Nat fields hold values under 2^64.
452def put.u64(b: Bytes.Bytes, +at: U32, +n: Nat) -> Bytes.Bytes:
453 Bytes.set.u32le(Bytes.set.u32le(b, at, U32.from_nat(Nat.mod(n, W()))), (at + 4 : U32), U32.from_nat(Nat.div(n, W())))
454
455def head(+tag: U32, +a: Nat, +c: Nat) -> Bytes.Bytes:
456 put.u64(put.u64(Bytes.set.u32le(Bytes.new(20), 0, tag), 4, a), 12, c)
457
458def snap.u32(out: Bytes.Bytes, +v: U32) -> Bytes.Bytes:
459 Bytes.append(out, Bytes.set.u32le(Bytes.new(4), 0, v))
460
461def snap.u64(out: Bytes.Bytes, +n: Nat) -> Bytes.Bytes:
462 Bytes.append(out, put.u64(Bytes.new(8), 0, n))
463
464def snap.chars(s: String, out: Bytes.Bytes) -> Bytes.Bytes:
465 match s:
466 case SNil{}:
467 out
468 case SCon{Chr{c}, t}:
469 snap.chars(t, snap.u32(out, c))
470
471# A target is a u32 count of chars, then each char as a u32.
472def snap.key(out: Bytes.Bytes, +k: String) -> Bytes.Bytes:
473 snap.chars(k, snap.u32(out, Bytes.count(k, 0)))
474
475def snap.nats(xs: List<&2, Nat>, out: Bytes.Bytes) -> Bytes.Bytes:
476 match xs:
477 case Nil{}:
478 out
479 case Con{x, rest}:
480 snap.nats(rest, snap.u64(out, x))
481
482# A breaker state is a u32 kind. 0 is closed: a u32 count, then each failure as a u64. 1 is open: until. 2 is half-open: busy.
483def snap.brk(out: Bytes.Bytes, b: Retry.State) -> Bytes.Bytes:
484 match b:
485 case Retry.CircuitClosed{+fs}:
486 snap.nats(fs, snap.u32(snap.u32(out, 0), U32.from_nat(List.length(&2, Nat, fs))))
487 case Retry.CircuitOpen{u}:
488 snap.u64(snap.u32(out, 1), u)
489 case Retry.CircuitHalf{k}:
490 snap.u64(snap.u32(out, 2), k)
491
492def encode(~A: Data, ~penc: A -> Bytes.Bytes, op: Op<A>) -> Bytes.Bytes:
493 match op:
494 case Enqueue{+d, x}:
495 Bytes.append(put.u64(Bytes.set.u32le(Bytes.new(12), 0, 1), 4, d), penc(x))
496 case Select{+now}:
497 head(2, now, 0n)
498 case Complete{+i}:
499 head(3, i, 0n)
500 case Cancel{+i}:
501 head(4, i, 0n)
502 case Requeue{+i, +d}:
503 head(5, i, d)
504 case Defer{+i, +d}:
505 head(6, i, d)
506 case Abandon{+i, w, +at}:
507 Bytes.append(head(8, i, why.code(w)), put.u64(Bytes.new(8), 0, at))
508 case Revive{+i, +d}:
509 head(9, i, d)
510 case Purge{+t}:
511 head(11, t, 0n)
512 case PurgeAll{}:
513 head(12, 0n, 0n)
514 case Break{k, b}:
515 snap.brk(snap.key(snap.u32(Bytes.new(0), 10), k), b)
516
517def get.field(m: Maybe<&2, U32>) -> U32:
518 match m:
519 case None{}:
520 0
521 case Some{x}:
522 x
523
524def get.u32(r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & U32:
525 (b, m) = r
526 (b, get.field(m))
527
528def get.hi(+lo: U32, r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & Nat:
529 (b, m) = r
530 (b, Nat.add(U32.to_nat(lo), Nat.mul(U32.to_nat(get.field(m)), W())))
531
532def get.lo(+at: U32, r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & Nat:
533 (b, m) = r
534 +lo = get.field(m)
535 get.hi(lo, Bytes.get.u32le(b, (at + 4 : U32)))
536
537def get.u64(b: Bytes.Bytes, +at: U32) -> Bytes.Bytes & Nat:
538 get.lo(at, Bytes.get.u32le(b, at))
539
540# ---- the snapshot codec: tag 7 and the next id, then the heap, the running list, the tries, the dead tickets, and the breakers.
541# A u32 flag starts each tree node and list cell (1) and marks each end (0), so decode rebuilds the same shape.
542# A ticket is its u64 id and deadline, then a u32 length and the payload.
543# The dead tickets are a trie: each node is a u32 kind, 0 empty, 1 a bucket, or 2 a branch, then its lo and hi nodes.
544# A bucket is its u32 hash, then a list of entries: the u64 key, the ticket, a u32 why.code, and the u64 abandon time.
545# A breaker is its target, then its state, as in a Break record.
546
547def snap.payload(out: Bytes.Bytes, p: Bytes.Bytes) -> Bytes.Bytes:
548 Bytes.Bytes{+len, buf} = p
549 Bytes.append(snap.u32(out, len), Bytes.Bytes{len, buf})
550
551def snap.ticket(~A: Data, ~penc: A -> Bytes.Bytes, out: Bytes.Bytes, t: Q.Ticket<A>) -> Bytes.Bytes:
552 Q.Ticket{+i, +d, x} = t
553 snap.payload(snap.u64(snap.u64(out, i), d), penc(x))
554
555def snap.heap(~A: Data, ~penc: A -> Bytes.Bytes, h: H.Heap<Q.Ticket<A>>, out: Bytes.Bytes) -> Bytes.Bytes:
556 match h:
557 case H.HLeaf{}:
558 snap.u32(out, 0)
559 case H.HNode{+n, t, l, r}:
560 snap.heap(~A, ~penc, r, snap.heap(~A, ~penc, l, snap.ticket(~A, ~penc, snap.u64(snap.u32(out, 1), n), t)))
561
562def snap.run(~A: Data, ~penc: A -> Bytes.Bytes, xs: List<&2, Q.Ticket<A>>, out: Bytes.Bytes) -> Bytes.Bytes:
563 match xs:
564 case Nil{}:
565 snap.u32(out, 0)
566 case Con{t, rest}:
567 snap.run(~A, ~penc, rest, snap.ticket(~A, ~penc, snap.u32(out, 1), t))
568
569def snap.tries(ts: Tries(), out: Bytes.Bytes) -> Bytes.Bytes:
570 match ts:
571 case O.OTip{}:
572 snap.u32(out, 0)
573 case O.OBin{+n, +k, Try{+f, +st}, lo, hi}:
574 snap.tries(hi, snap.tries(lo, snap.u64(snap.u64(snap.u64(snap.u32(snap.u32(out, 1), n), k), f), st)))
575
576def snap.entries(~A: Data, ~penc: A -> Bytes.Bytes, es: List<&2, M.Entry<Nat, Dead<A>>>, out: Bytes.Bytes) -> Bytes.Bytes:
577 match es:
578 case Nil{}:
579 snap.u32(out, 0)
580 case Con{M.Entry{k, Dead{t, w, at}}, rest}:
581 snap.entries(~A, ~penc, rest, snap.u64(snap.u32(snap.ticket(~A, ~penc, snap.u64(snap.u32(out, 1), k), t), U32.from_nat(why.code(w))), at))
582
583def snap.graves(~A: Data, ~penc: A -> Bytes.Bytes, ds: Graves(A), out: Bytes.Bytes) -> Bytes.Bytes:
584 match ds:
585 case M.HNil{}:
586 snap.u32(out, 0)
587 case M.HLeaf{h, es}:
588 snap.entries(~A, ~penc, es, snap.u32(snap.u32(out, 1), h))
589 case M.HBranch{lo, hi}:
590 snap.graves(~A, ~penc, hi, snap.graves(~A, ~penc, lo, snap.u32(out, 2)))
591
592def snap.brks(xs: List<&2, Sigma<&2, &2, String, _ => Retry.State>>, out: Bytes.Bytes) -> Bytes.Bytes:
593 match xs:
594 case Nil{}:
595 snap.u32(out, 0)
596 case Con{(k, b), rest}:
597 snap.brks(rest, snap.brk(snap.key(snap.u32(out, 1), k), b))
598
599# The Snap record of s.
600def encode.snap(~A: Data, ~penc: A -> Bytes.Bytes, s: State<A>) -> Bytes.Bytes:
601 State{Q.State{+n, h, run}, ts, ds, bs} = s
602 snap.brks(Map.to_list(&2, Retry.State, bs),
603 snap.graves(~A, ~penc, ds, snap.tries(ts, snap.run(~A, ~penc, run, snap.heap(~A, ~penc, h, snap.u64(snap.u32(Bytes.new(0), 7), n))))))
604
605def encode.rec(~A: Data, ~penc: A -> Bytes.Bytes, r: Rec<A>) -> Bytes.Bytes:
606 match r:
607 case Snap{s}:
608 encode.snap(~A, ~penc, s)
609 case Do{op}:
610 encode(~A, ~penc, op)
611
612# A snapshot reader: the record, and the offset of the next field.
613type Rd is Type:
614 Rd{b: Bytes.Bytes, at: U32}
615
616# One step of the snapshot decoder. None: a field runs past the record or does not decode.
617def Dec(-T: Type) -> Type:
618 Rd -> Maybe<&1, Rd & T>
619
620def Dec.next(-A: Type, -B: Type, m: Maybe<&1, Rd & A>, f: A -> Dec(B)) -> Maybe<&1, Rd & B>:
621 match m:
622 case None{}:
623 None{}
624 case Some{(r, x)}:
625 f(x)(r)
626
627def Dec.bind(-A: Type, -B: Type, m: Dec(A), f: A -> Dec(B)) -> Dec(B):
628 r => Dec.next(A, B, m(r), f)
629
630def Dec.pure(-A: Type, x: A) -> Dec(A):
631 r => Some{(r, x)}
632
633def Dec.fail(-A: Type) -> Dec(A):
634 r => None{}
635
636def rd.u32.of(m: Maybe<&2, U32>, b: Bytes.Bytes, +at: U32) -> Maybe<&1, Rd & U32>:
637 match m:
638 case None{}:
639 None{}
640 case Some{x}:
641 Some{(Rd{b, (at + 4 : U32)}, x)}
642
643def rd.u32.got(+at: U32, r: Bytes.Bytes & Maybe<&2, U32>) -> Maybe<&1, Rd & U32>:
644 (b, m) = r
645 rd.u32.of(m, b, at)
646
647def rd.u32.at(r: Rd) -> Maybe<&1, Rd & U32>:
648 Rd{b, +at} = r
649 rd.u32.got(at, Bytes.get.u32le(b, at))
650
651def rd.u32() -> Dec(U32):
652 r => rd.u32.at(r)
653
654def rd.u64.of(+lo: U32, +hi: U32) -> Nat:
655 Nat.add(U32.to_nat(lo), Nat.mul(U32.to_nat(hi), W()))
656
657def rd.u64() -> Dec(Nat):
658 do Dec<Nat>:
659 lo : U32 <- rd.u32()
660 hi : U32 <- rd.u32()
661 return rd.u64.of(lo, hi)
662
663def rd.cut.got(+at: U32, +n: U32, r: Bytes.Bytes & Bytes.Bytes) -> Maybe<&1, Rd & Bytes.Bytes>:
664 (b, p) = r
665 Some{(Rd{b, (at + n : U32)}, p)}
666
667def rd.cut.if(ok: Bool, b: Bytes.Bytes, +at: U32, +n: U32) -> Maybe<&1, Rd & Bytes.Bytes>:
668 match ok:
669 case False{}:
670 None{}
671 case True{}:
672 rd.cut.got(at, n, Bytes.slice(b, at, n))
673
674def rd.cut.at(+n: U32, r: Rd) -> Maybe<&1, Rd & Bytes.Bytes>:
675 Rd{Bytes.Bytes{+len, buf}, +at} = r
676 rd.cut.if(Bytes.fits(len, at, n), Bytes.Bytes{len, buf}, at, n)
677
678# The next n octets.
679def rd.cut(+n: U32) -> Dec(Bytes.Bytes):
680 r => rd.cut.at(n, r)
681
682def rd.flag.of(+m: U32) -> Dec(Bool):
683 Bool.pick(Dec(Bool), U32.is_eq(m, 0), Dec.pure(Bool, False{}), Bool.pick(Dec(Bool), U32.is_eq(m, 1), Dec.pure(Bool, True{}), Dec.fail(Bool)))
684
685# A u32 flag: 1 is True, 0 is False, and any other value fails.
686def rd.flag() -> Dec(Bool):
687 Dec.bind(U32, Bool, rd.u32(), m => rd.flag.of(m))
688
689def rd.payload(-A: Data, +i: Nat, +d: Nat, m: Maybe<&2, A>) -> Dec(Q.Ticket<A>):
690 match m:
691 case None{}:
692 Dec.fail(Q.Ticket<A>)
693 case Some{x}:
694 Dec.pure(Q.Ticket<A>, Q.Ticket{i, d, x})
695
696def rd.ticket(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>) -> Dec(Q.Ticket<A>):
697 do Dec<Q.Ticket<A>>:
698 i : Nat <- rd.u64()
699 d : Nat <- rd.u64()
700 n : U32 <- rd.u32()
701 p : Bytes.Bytes <- rd.cut(n)
702 rd.payload(A, i, d, pdec(p))
703
704# Each rd.* tree reader takes the flag already read. fuel bounds the depth: every node holds at least one 4-octet flag.
705def rd.heap(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +fuel: Nat, node: Bool) -> Dec(H.Heap<Q.Ticket<A>>):
706 match fuel node:
707 case 0n b:
708 Dec.fail(H.Heap<Q.Ticket<A>>)
709 case 1n+f False{}:
710 Dec.pure(H.Heap<Q.Ticket<A>>, H.HLeaf{})
711 case 1n+f True{}:
712 do Dec<H.Heap<Q.Ticket<A>>>:
713 n : Nat <- rd.u64()
714 t : Q.Ticket<A> <- rd.ticket(~A, ~pdec)
715 lf : Bool <- rd.flag()
716 l : H.Heap<Q.Ticket<A>> <- rd.heap(~A, ~pdec, f, lf)
717 rf : Bool <- rd.flag()
718 r : H.Heap<Q.Ticket<A>> <- rd.heap(~A, ~pdec, f, rf)
719 return H.HNode{n, t, l, r}
720
721def rd.run(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +fuel: Nat, more: Bool) -> Dec(List<&2, Q.Ticket<A>>):
722 match fuel more:
723 case 0n b:
724 Dec.fail(List<&2, Q.Ticket<A>>)
725 case 1n+f False{}:
726 Dec.pure(List<&2, Q.Ticket<A>>, Nil{})
727 case 1n+f True{}:
728 do Dec<List<&2, Q.Ticket<A>>>:
729 t : Q.Ticket<A> <- rd.ticket(~A, ~pdec)
730 m : Bool <- rd.flag()
731 rest : List<&2, Q.Ticket<A>> <- rd.run(~A, ~pdec, f, m)
732 return Con{t, rest}
733
734def rd.tries(+fuel: Nat, node: Bool) -> Dec(O.OMap<Nat, Try>):
735 match fuel node:
736 case 0n b:
737 Dec.fail(O.OMap<Nat, Try>)
738 case 1n+f False{}:
739 Dec.pure(O.OMap<Nat, Try>, O.OTip{})
740 case 1n+f True{}:
741 do Dec<O.OMap<Nat, Try>>:
742 n : U32 <- rd.u32()
743 k : Nat <- rd.u64()
744 fails : Nat <- rd.u64()
745 st : Nat <- rd.u64()
746 lf : Bool <- rd.flag()
747 lo : O.OMap<Nat, Try> <- rd.tries(f, lf)
748 hf : Bool <- rd.flag()
749 hi : O.OMap<Nat, Try> <- rd.tries(f, hf)
750 return O.OBin{n, k, Try{fails, st}, lo, hi}
751
752def rd.why(+c: U32) -> Dec(Why):
753 Bool.pick(Dec(Why), U32.is_eq(c, 0), Dec.pure(Why, WhySpent{}),
754 Bool.pick(Dec(Why), U32.is_eq(c, 1), Dec.pure(Why, WhyLate{}),
755 Bool.pick(Dec(Why), U32.is_eq(c, 2), Dec.pure(Why, WhyUnsafe{}),
756 Bool.pick(Dec(Why), U32.is_eq(c, 3), Dec.pure(Why, WhyFailed{}), Dec.fail(Why)))))
757
758def rd.entries(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +fuel: Nat, more: Bool) -> Dec(List<&2, M.Entry<Nat, Dead<A>>>):
759 match fuel more:
760 case 0n b:
761 Dec.fail(List<&2, M.Entry<Nat, Dead<A>>>)
762 case 1n+f False{}:
763 Dec.pure(List<&2, M.Entry<Nat, Dead<A>>>, Nil{})
764 case 1n+f True{}:
765 do Dec<List<&2, M.Entry<Nat, Dead<A>>>>:
766 k : Nat <- rd.u64()
767 t : Q.Ticket<A> <- rd.ticket(~A, ~pdec)
768 c : U32 <- rd.u32()
769 w : Why <- rd.why(c)
770 at : Nat <- rd.u64()
771 m : Bool <- rd.flag()
772 rest : List<&2, M.Entry<Nat, Dead<A>>> <- rd.entries(~A, ~pdec, f, m)
773 return Con{M.Entry{k, Dead{t, w, at}}, rest}
774
775# A trie node whose kind is already read: nil is kind 0, leaf kind 1, and branch kind 2. Any other kind fails.
776def rd.graves(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +fuel: Nat, nil: Bool, leaf: Bool, branch: Bool) -> Dec(Graves(A)):
777 match fuel nil leaf branch:
778 case 0n a b c:
779 Dec.fail(Graves(A))
780 case 1n+f True{} b c:
781 Dec.pure(Graves(A), M.HNil{})
782 case 1n+f False{} True{} c:
783 do Dec<Graves(A)>:
784 h : U32 <- rd.u32()
785 m : Bool <- rd.flag()
786 es : List<&2, M.Entry<Nat, Dead<A>>> <- rd.entries(~A, ~pdec, f, m)
787 return M.HLeaf{h, es}
788 case 1n+f False{} False{} True{}:
789 do Dec<Graves(A)>:
790 +lk : U32 <- rd.u32()
791 lo : Graves(A) <- rd.graves(~A, ~pdec, f, U32.is_eq(lk, 0), U32.is_eq(lk, 1), U32.is_eq(lk, 2))
792 +hk : U32 <- rd.u32()
793 hi : Graves(A) <- rd.graves(~A, ~pdec, f, U32.is_eq(hk, 0), U32.is_eq(hk, 1), U32.is_eq(hk, 2))
794 return M.HBranch{lo, hi}
795 case 1n+f False{} False{} False{}:
796 Dec.fail(Graves(A))
797
798# Each rd.* sequence reader takes the count or flag already read. fuel bounds its length: every item holds at least 4 octets.
799def rd.chars(+fuel: Nat, end: Bool, +n: U32) -> Dec(String):
800 match fuel end:
801 case 0n b:
802 Dec.fail(String)
803 case 1n+f True{}:
804 Dec.pure(String, SNil{})
805 case 1n+f False{}:
806 +k = (n - 1 : U32)
807 do Dec<String>:
808 c : U32 <- rd.u32()
809 rest : String <- rd.chars(f, U32.is_eq(k, 0), k)
810 return SCon{Chr{c}, rest}
811
812def rd.key(+fuel: Nat) -> Dec(String):
813 do Dec<String>:
814 +n : U32 <- rd.u32()
815 rd.chars(fuel, U32.is_eq(n, 0), n)
816
817def rd.nats(+fuel: Nat, end: Bool, +n: U32) -> Dec(List<&2, Nat>):
818 match fuel end:
819 case 0n b:
820 Dec.fail(List<&2, Nat>)
821 case 1n+f True{}:
822 Dec.pure(List<&2, Nat>, Nil{})
823 case 1n+f False{}:
824 +k = (n - 1 : U32)
825 do Dec<List<&2, Nat>>:
826 x : Nat <- rd.u64()
827 rest : List<&2, Nat> <- rd.nats(f, U32.is_eq(k, 0), k)
828 return Con{x, rest}
829
830def rd.closed(+fuel: Nat) -> Dec(Retry.State):
831 do Dec<Retry.State>:
832 +n : U32 <- rd.u32()
833 fs : List<&2, Nat> <- rd.nats(fuel, U32.is_eq(n, 0), n)
834 return Retry.CircuitClosed{fs}
835
836def rd.brk.of(+fuel: Nat, +kind: U32) -> Dec(Retry.State):
837 Bool.pick(Dec(Retry.State), U32.is_eq(kind, 0), rd.closed(fuel),
838 Bool.pick(Dec(Retry.State), U32.is_eq(kind, 1), Dec.bind(Nat, Retry.State, rd.u64(), u => Dec.pure(Retry.State, Retry.CircuitOpen{u})),
839 Bool.pick(Dec(Retry.State), U32.is_eq(kind, 2), Dec.bind(Nat, Retry.State, rd.u64(), k => Dec.pure(Retry.State, Retry.CircuitHalf{k})), Dec.fail(Retry.State))))
840
841def rd.brk(+fuel: Nat) -> Dec(Retry.State):
842 Dec.bind(U32, Retry.State, rd.u32(), k => rd.brk.of(fuel, k))
843
844def rd.break(-A: Data, +fuel: Nat) -> Dec(Op<A>):
845 do Dec<Op<A>>:
846 k : String <- rd.key(fuel)
847 b : Retry.State <- rd.brk(fuel)
848 return Break{k, b}
849
850def rd.brks(+fuel: Nat, more: Bool, acc: Map<&2, Retry.State>) -> Dec(Map<&2, Retry.State>):
851 match fuel more:
852 case 0n b:
853 Dec.fail(Map<&2, Retry.State>)
854 case 1n+f False{}:
855 Dec.pure(Map<&2, Retry.State>, acc)
856 case 1n+f True{}:
857 do Dec<Map<&2, Retry.State>>:
858 k : String <- rd.key(f)
859 b : Retry.State <- rd.brk(f)
860 m : Bool <- rd.flag()
861 rd.brks(f, m, Map.set(&2, Retry.State, acc, k, b))
862
863def rd.state(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +fuel: Nat) -> Dec(State<A>):
864 do Dec<State<A>>:
865 n : Nat <- rd.u64()
866 hf : Bool <- rd.flag()
867 h : H.Heap<Q.Ticket<A>> <- rd.heap(~A, ~pdec, fuel, hf)
868 rf : Bool <- rd.flag()
869 run : List<&2, Q.Ticket<A>> <- rd.run(~A, ~pdec, fuel, rf)
870 tf : Bool <- rd.flag()
871 ts : O.OMap<Nat, Try> <- rd.tries(fuel, tf)
872 +dk : U32 <- rd.u32()
873 ds : Graves(A) <- rd.graves(~A, ~pdec, fuel, U32.is_eq(dk, 0), U32.is_eq(dk, 1), U32.is_eq(dk, 2))
874 bf : Bool <- rd.flag()
875 bs : Map<&2, Retry.State> <- rd.brks(fuel, bf, Map.new(&2, Retry.State))
876 return State{Q.State{n, h, run}, ts, ds, bs}
877
878# The value read, when the reader ended at len, the record's end.
879def rd.done(-T: Data, +len: U32, m: Maybe<&1, Rd & T>) -> Maybe<&2, T>:
880 match m:
881 case None{}:
882 None{}
883 case Some{(Rd{b, +at}, +x)}:
884 Bool.pick(Maybe<&2, T>, U32.is_eq(at, len), Some{x}, None{})
885
886# The Abandon of ticket a at e whose why.code is c, or None for any other code.
887def decode.abandon(-A: Data, +a: Nat, +c: Nat, +e: Nat) -> Maybe<&2, Op<A>>:
888 Bool.pick(Maybe<&2, Op<A>>, Nat.is_eq(c, 0n), Some{Abandon{a, WhySpent{}, e}},
889 Bool.pick(Maybe<&2, Op<A>>, Nat.is_eq(c, 1n), Some{Abandon{a, WhyLate{}, e}},
890 Bool.pick(Maybe<&2, Op<A>>, Nat.is_eq(c, 2n), Some{Abandon{a, WhyUnsafe{}, e}},
891 Bool.pick(Maybe<&2, Op<A>>, Nat.is_eq(c, 3n), Some{Abandon{a, WhyFailed{}, e}}, None{}))))
892
893def decode.small(-A: Data, ok: Bool, +tag: U32, +a: Nat, +c: Nat) -> Maybe<&2, Op<A>>:
894 match ok:
895 case False{}:
896 None{}
897 case True{}:
898 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 2), Some{Select{a}},
899 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 3), Some{Complete{a}},
900 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 4), Some{Cancel{a}},
901 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 5), Some{Requeue{a, c}},
902 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 6), Some{Defer{a, c}},
903 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 9), Some{Revive{a, c}},
904 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 11), Some{Purge{a}},
905 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 12), Some{PurgeAll{}}, None{}))))))))
906
907def decode.long(-A: Data, ok: Bool, +a: Nat, +c: Nat, r: Bytes.Bytes & Nat) -> Maybe<&2, Op<A>>:
908 match ok:
909 case False{}:
910 None{}
911 case True{}:
912 (b, +e) = r
913 decode.abandon(A, a, c, e)
914
915def decode.payload(-A: Data, m: Maybe<&2, A>, +d: Nat) -> Maybe<&2, Op<A>>:
916 match m:
917 case None{}:
918 None{}
919 case Some{x}:
920 Some{Enqueue{d, x}}
921
922def decode.c.if(-A: Data, abandon: Bool, +tag: U32, +len: U32, +a: Nat, +c: Nat, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
923 match abandon:
924 case True{}:
925 decode.long(A, U32.is_eq(len, 28), a, c, get.u64(b, 20))
926 case False{}:
927 decode.small(A, U32.is_eq(len, 20), tag, a, c)
928
929# An Abandon is 28 octets; every other op without a payload is 20.
930def decode.c(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +tag: U32, +len: U32, +a: Nat, r: Bytes.Bytes & Nat) -> Maybe<&2, Op<A>>:
931 (b, +c) = r
932 decode.c.if(A, U32.is_eq(tag, 8), tag, len, a, c, b)
933
934def decode.kind(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, enq: Bool, +tag: U32, +len: U32, +a: Nat, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
935 match enq:
936 case True{}:
937 decode.payload(A, pdec(Bytes.snd(Bytes.slice(b, 12, (len - 12 : U32)))), a)
938 case False{}:
939 decode.c(~A, ~pdec, tag, len, a, get.u64(b, 12))
940
941def decode.a(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +tag: U32, +len: U32, r: Bytes.Bytes & Nat) -> Maybe<&2, Op<A>>:
942 (b, +a) = r
943 decode.kind(~A, ~pdec, U32.is_eq(tag, 1), tag, len, a, b)
944
945def decode.tag.if(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, brk: Bool, +tag: U32, +len: U32, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
946 match brk:
947 case True{}:
948 rd.done(Op<A>, len, rd.break(A, U32.to_nat((len / 4 + 1 : U32)))(Rd{b, 4}))
949 case False{}:
950 decode.a(~A, ~pdec, tag, len, get.u64(b, 4))
951
952def decode.tag(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +len: U32, r: Bytes.Bytes & U32) -> Maybe<&2, Op<A>>:
953 (b, +tag) = r
954 decode.tag.if(~A, ~pdec, U32.is_eq(tag, 10), tag, len, b)
955
956def decode.len(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, ok: Bool, +len: U32, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
957 match ok:
958 case False{}:
959 None{}
960 case True{}:
961 decode.tag(~A, ~pdec, len, get.u32(Bytes.get.u32le(b, 0)))
962
963# The op of a record, or None when it is not one that encode writes.
964def decode(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
965 Bytes.Bytes{+len, buf} = b
966 decode.len(~A, ~pdec, U32.is_ge(len, 12), len, Bytes.Bytes{len, buf})
967
968# The state of a Snap record whose tag is already checked. The decoder must end at the record's end.
969def decode.snap(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, b: Bytes.Bytes) -> Maybe<&2, State<A>>:
970 Bytes.Bytes{+len, buf} = b
971 rd.done(State<A>, len, rd.state(~A, ~pdec, U32.to_nat((len / 4 + 1 : U32)))(Rd{Bytes.Bytes{len, buf}, 4}))
972
973def decode.snapped(-A: Data, m: Maybe<&2, State<A>>) -> Maybe<&2, Rec<A>>:
974 match m:
975 case None{}:
976 None{}
977 case Some{s}:
978 Some{Snap{s}}
979
980def decode.did(-A: Data, m: Maybe<&2, Op<A>>) -> Maybe<&2, Rec<A>>:
981 match m:
982 case None{}:
983 None{}
984 case Some{op}:
985 Some{Do{op}}
986
987def decode.rec.if(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, snap: Bool, b: Bytes.Bytes) -> Maybe<&2, Rec<A>>:
988 match snap:
989 case True{}:
990 decode.snapped(A, decode.snap(~A, ~pdec, b))
991 case False{}:
992 decode.did(A, decode(~A, ~pdec, b))
993
994def decode.rec.tag(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, r: Bytes.Bytes & U32) -> Maybe<&2, Rec<A>>:
995 (b, +tag) = r
996 decode.rec.if(~A, ~pdec, U32.is_eq(tag, 7), b)
997
998# The Rec of a journal record, or None when it is neither a Snap nor an op that encode.rec writes.
999def decode.rec(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, b: Bytes.Bytes) -> Maybe<&2, Rec<A>>:
1000 decode.rec.tag(~A, ~pdec, get.u32(Bytes.get.u32le(b, 0)))
1001
1002# ---- the runner
1003
1004# policy: retry's policy for each ticket. circuit: the breaker of each target. idle: ms that drain waits when no attempt started.
1005# compact: tick compacts the journal once records past this many octets were appended since open or the last compaction; 0 never.
1006type Config is Data:
1007 Config{policy: Retry.Policy, circuit: Retry.Circuit, idle: U32, compact: U32}
1008
1009# The journal, its path, its file cap, and its length at open or at the last compaction.
1010type Log is Type:
1011 Log{journal: J.Journal, path: String, limit: U32, base: U32}
1012
1013# An attempt that runs: its unit of the pool, the budget that admit left, and its target.
1014type Flight<-A: Data> is Type:
1015 Flight{ticket: Q.Ticket<A>, grant: Res.Grant, budget: Retry.Budget, target: String}
1016
1017def Out(-X: Type) -> Type:
1018 Result<&1, &1, U32 & String, X>
1019
1020# A message to the fiber that owns the runner. Ended: an attempt finished. Add and Drop: another fiber asks for an enqueue or a cancel.
1021type Msg<-A: Data> is Type:
1022 Ended{id: Nat, outcome: Retry.Outcome}
1023 Add{deadline: Nat, payload: A, reply: Chan(Out(Nat))}
1024 Drop{id: Nat, reply: Chan(Out(Unit))}
1025
1026# An open runner. Replaying its journal gives its state; its pool bounds the attempts that run at once.
1027# Each attempt sends its outcome, and each other fiber its ask, on inbox. flights are the attempts that run.
1028type Runner<-A: Data> is Type:
1029 Runner{log: Log, state: State<A>, pool: Res.Pool, config: Config, inbox: Chan(Msg<A>), flights: List<&1, Flight<A>>}
1030
1031# The runner, the claim fuel left, and the first error.
1032def Claimed(-A: Data) -> Type:
1033 Runner<A> & Nat & Out(Unit)
1034
1035def Ran(-A: Data) -> Type:
1036 Runner<A> & Out(Unit)
1037
1038# Wall-clock ms since the Unix epoch. Deadlines must keep their meaning across a restart.
1039def clock() -> IO(Nat):
1040 do IO<Nat>:
1041 t : Time.Instant <- Time.now()
1042 return Time.Duration.to_ms_nat(Time.Instant.since_epoch(t))
1043
1044def first(a: Out(Unit), b: Out(Unit)) -> Out(Unit):
1045 match a:
1046 case Fail{e}:
1047 Fail{e}
1048 case Done{u}:
1049 b
1050
1051def log.appended(+path: String, +limit: U32, +base: U32, x: J.Journal & Out(Unit)) -> Log & Out(Unit):
1052 (j, o) = x
1053 (Log{j, path, limit, base}, o)
1054
1055def log.append(l: Log, p: Bytes.Bytes) -> IO(Log & Out(Unit)):
1056 Log{j, +path, +limit, +base} = l
1057 do IO<Log & Out(Unit)>:
1058 x : J.Journal & Out(Unit) <- J.append(j, p)
1059 return log.appended(path, limit, base, x)
1060
1061def log.close(l: Log) -> IO(Unit):
1062 Log{j, path, limit, base} = l
1063 J.close(j)
1064
1065# The journal reads with limit as its record cap, so that a snapshot fits; appends keep max.
1066def log.of(j: J.Journal, +max: U32, path: String, +limit: U32) -> Log:
1067 J.Journal{file, cap, +end, ok} = j
1068 Log{J.Journal{file, max, end, ok}, path, limit, end}
1069
1070def commit.done(~A: Data, x: Log & Out(Unit), s: State<A>, +op: Op<A>, p: Res.Pool, c: Config, ib: Chan(Msg<A>), fs: List<&1, Flight<A>>) -> Ran(A):
1071 match x:
1072 case (j, Done{u}):
1073 (Runner{j, step(~A, s, op), p, c, ib, fs}, Done{u})
1074 case (j, Fail{e}):
1075 (Runner{j, s, p, c, ib, fs}, Fail{e})
1076
1077# Appends op, and applies it once the append is durable. After a failed append the state is as it was,
1078# and the journal refuses every later append until the runner is reopened.
1079def commit(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +op: Op<A>) -> IO(Ran(A)):
1080 Runner{j, s, p, c, ib, fs} = r
1081 do IO<Ran(A)>:
1082 x : Log & Out(Unit) <- log.append(j, encode(~A, ~penc, op))
1083 return commit.done(~A, x, s, op, p, c, ib, fs)
1084
1085def enqueue.done(-A: Data, +id: Nat, y: Ran(A)) -> Runner<A> & Out(Nat):
1086 match y:
1087 case (r, Done{u}):
1088 (r, Done{id})
1089 case (r, Fail{e}):
1090 (r, Fail{e})
1091
1092# Adds a job that is due at deadline (wall-clock ms) and answers its ticket id once the record is durable.
1093def enqueue(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +deadline: Nat, x: A) -> IO(Runner<A> & Out(Nat)):
1094 Runner{j, +s, p, c, ib, fs} = r
1095 do IO<Runner<A> & Out(Nat)>:
1096 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, c, ib, fs}, Enqueue{deadline, x})
1097 return enqueue.done(A, Q.next_id(A, queue(A, s)), y)
1098
1099# Cancels ticket id. A running attempt finishes, but its ticket is never selected again. A dead ticket is dropped.
1100def cancel(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +id: Nat) -> IO(Ran(A)):
1101 commit(~A, ~penc, r, Cancel{id})
1102
1103# Makes dead ticket id pending again at deadline (wall-clock ms), with its payload and a new retry budget.
1104# A ticket that is not dead does not change.
1105def revive(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +id: Nat, +deadline: Nat) -> IO(Ran(A)):
1106 commit(~A, ~penc, r, Revive{id, deadline})
1107
1108# Drops, as one record, the dead tickets that retry gave up on before `before` (wall-clock ms).
1109def purge(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +before: Nat) -> IO(Ran(A)):
1110 commit(~A, ~penc, r, Purge{before})
1111
1112# Drops every dead ticket, as one record.
1113def purge.all(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>) -> IO(Ran(A)):
1114 commit(~A, ~penc, r, PurgeAll{})
1115
1116# ---- asks from other fibers
1117
1118# The runner back, and its inbox. Another fiber passes the inbox to ask.enqueue and ask.cancel.
1119def inbox(-A: Data, r: Runner<A>) -> Runner<A> & Chan(Msg<A>):
1120 Runner{j, s, p, c, +ib, fs} = r
1121 (Runner{j, s, p, c, ib, fs}, ib)
1122
1123def ask.answer(-X: Type, m: Maybe<&1, Out(X)>) -> Out(X):
1124 match m:
1125 case None{}:
1126 Fail{(32, "runner: the runner closed before it answered")}
1127 case Some{o}:
1128 o
1129
1130def ask.sent(-A: Data, -X: Type, x: Result<&1, &1, Msg<A>, Unit>, +rep: Chan(Out(X))) -> IO(Out(X)):
1131 match x:
1132 case Fail{m}:
1133 IO.pure(Out(X), Fail{(32, "runner: the inbox is closed")})
1134 case Done{u}:
1135 do IO<Out(X)>:
1136 a : Maybe<&1, Out(X)> <- Chan.recv(Out(X), rep)
1137 return ask.answer(X, a)
1138
1139# Sends m, built with a new reply channel, on the inbox and waits for the reply.
1140def ask(-A: Data, -X: Type, +ib: Chan(Msg<A>), m: Chan(Out(X)) -> Msg<A>) -> IO(Out(X)):
1141 do IO<Out(X)>:
1142 +rep : Chan(Out(X)) <- Chan.new(Out(X), 1)
1143 x : Result<&1, &1, Msg<A>, Unit> <- Chan.send(Msg<A>, ib, m(rep))
1144 ask.sent(A, X, x, rep)
1145
1146# From another fiber: adds a job due at deadline, and answers its ticket id once the record is durable.
1147# The answer comes when the fiber that owns the runner reads the inbox, in tick or drain.
1148def ask.enqueue(-A: Data, +ib: Chan(Msg<A>), +deadline: Nat, x: A) -> IO(Out(Nat)):
1149 ask(A, Nat, ib, rep => Add{deadline, x, rep})
1150
1151# From another fiber: cancels ticket id, as cancel does. The answer comes when the owner reads the inbox.
1152def ask.cancel(-A: Data, +ib: Chan(Msg<A>), +id: Nat) -> IO(Out(Unit)):
1153 ask(A, Unit, ib, rep => Drop{id, rep})
1154
1155# ---- one round
1156
1157# A grant of this runner's pool always fits it, so Kept does not happen.
1158def release.got(-A: Data, x: Res.Release, j: Log, s: State<A>, c: Config, ib: Chan(Msg<A>), fs: List<&1, Flight<A>>) -> Runner<A>:
1159 match x:
1160 case Res.Released{p}:
1161 Runner{j, s, p, c, ib, fs}
1162 case Res.Kept{p, g}:
1163 Runner{j, s, p, c, ib, fs}
1164
1165def release(-A: Data, r: Runner<A>, g: Res.Grant) -> Runner<A>:
1166 Runner{j, s, p, c, ib, fs} = r
1167 release.got(A, Res.release(p, g), j, s, c, ib, fs)
1168
1169def claim.held(-A: Data, y: Ran(A), g: Res.Grant, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1170 match y:
1171 case (r, Fail{e}):
1172 IO.pure(Claimed(A), (release(A, r, g), 0n, Fail{e}))
1173 case (r, Done{u}):
1174 next(release(A, r, g))
1175
1176def claim.tag(-A: Data, +id: Nat, o: Retry.Outcome) -> IO(Msg<A>):
1177 IO.pure(Msg<A>, Ended{id, o})
1178
1179def trip.if(~A: Data, ~penc: A -> Bytes.Bytes, same: Bool, r: Runner<A>, +key: String, st: Retry.State) -> IO(Ran(A)):
1180 match same:
1181 case True{}:
1182 IO.pure(Ran(A), (r, Done{Unit{}}))
1183 case False{}:
1184 commit(~A, ~penc, r, Break{key, st})
1185
1186# Appends a Break when the target's breaker left old, so that a reopen restores it.
1187def trip(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +key: String, +old: Retry.State, br: Retry.Breaker) -> IO(Ran(A)):
1188 +st = brk.state(br, old)
1189 trip.if(~A, ~penc, brk.same(old, st), r, key, st)
1190
1191def claim.go(~A: Data, ~penc: A -> Bytes.Bytes, ~work: A -> IO(Retry.Outcome), +now: Nat, gate: Retry.Gate, +br: Retry.Breaker, b: Retry.Budget, +key: String,
1192 r: Runner<A>, +id: Nat, d: Nat, +x: A, g: Res.Grant, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1193 match gate:
1194 case Retry.GateGo{}:
1195 Runner{j, s, p, c, +ib, fs} = r
1196 do IO<Claimed(A)>:
1197 u : Chan(Msg<A>) <- IO.fork.go(Msg<A>, IO.bind(Retry.Outcome, Msg<A>, work(x), o => claim.tag(A, id, o)), ib)
1198 next(Runner{j, s, p, c, ib, Con{Flight{Q.Ticket{id, d, x}, g, b, key}, fs}})
1199 case Retry.GateNo{why}:
1200 do IO<Claimed(A)>:
1201 y : Ran(A) <- commit(~A, ~penc, r, held(A, why, br, id, now))
1202 claim.held(A, y, g, next)
1203
1204def claim.tripped(~A: Data, ~penc: A -> Bytes.Bytes, ~work: A -> IO(Retry.Outcome), +now: Nat, y: Ran(A), gate: Retry.Gate, +br: Retry.Breaker, b: Retry.Budget, +key: String,
1205 +id: Nat, d: Nat, +x: A, g: Res.Grant, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1206 match y:
1207 case (r, Fail{e}):
1208 IO.pure(Claimed(A), (release(A, r, g), 0n, Fail{e}))
1209 case (r, Done{u}):
1210 claim.go(~A, ~penc, ~work, now, gate, br, b, key, r, id, d, x, g, next)
1211
1212# A change to the breaker is durable before the attempt starts.
1213def claim.gate(~A: Data, ~penc: A -> Bytes.Bytes, ~work: A -> IO(Retry.Outcome), +now: Nat, a: Retry.Breaker & Retry.Budget & Retry.Gate, +key: String, +old: Retry.State,
1214 r: Runner<A>, +id: Nat, d: Nat, +x: A, g: Res.Grant, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1215 (+br, b, gate) = a
1216 do IO<Claimed(A)>:
1217 y : Ran(A) <- trip(~A, ~penc, r, key, old, br)
1218 claim.tripped(~A, ~penc, ~work, now, y, gate, br, b, key, id, d, x, g, next)
1219
1220# The selected ticket asks its target's breaker and its own budget for an attempt.
1221def claim.admit(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +now: Nat, r: Runner<A>, t: Q.Ticket<A>, g: Res.Grant,
1222 next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1223 Runner{j, +s, p, +c, ib, fs} = r
1224 Config{pol, circ, idle, every} = c
1225 Q.Ticket{+id, d, +x} = t
1226 +key = target(x)
1227 +old = brk.get(A, s, key)
1228 claim.gate(~A, ~penc, ~work, now, Retry.admit(Retry.BreakerOn{circ, old}, budget(pol, tries.get(tries(A, s), id)), now), key, old,
1229 Runner{j, s, p, c, ib, fs}, id, d, x, g, next)
1230
1231def claim.selected(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +now: Nat, y: Ran(A),
1232 t: Q.Ticket<A>, g: Res.Grant, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1233 match y:
1234 case (r, Fail{e}):
1235 IO.pure(Claimed(A), (release(A, r, g), 0n, Fail{e}))
1236 case (r, Done{u}):
1237 claim.admit(~A, ~penc, ~target, ~work, now, r, t, g, next)
1238
1239def claim.pick(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +left: Nat, +now: Nat, k: Pick<A>, j: Log, s: State<A>,
1240 c: Config, ib: Chan(Msg<A>), fs: List<&1, Flight<A>>, next: Runner<A> -> IO(Claimed(A))) -> IO(Claimed(A)):
1241 match k:
1242 case Idle{p}:
1243 IO.pure(Claimed(A), (Runner{j, s, p, c, ib, fs}, Nat.add(1n, left), Done{Unit{}}))
1244 case Picked{p, t, g}:
1245 do IO<Claimed(A)>:
1246 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, c, ib, fs}, Select{now})
1247 claim.selected(~A, ~penc, ~target, ~work, now, y, t, g, next)
1248
1249# Starts an attempt for each due ticket while the pool has a free unit; each attempt sends its outcome on the inbox.
1250# fuel bounds the tickets taken, and the fuel left comes back.
1251def claim(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), fuel: Nat, +now: Nat, r: Runner<A>) -> IO(Claimed(A)):
1252 match fuel:
1253 case 0n:
1254 IO.pure(Claimed(A), (r, 0n, Done{Unit{}}))
1255 case 1n+n:
1256 Runner{j, +s, p, c, ib, fs} = r
1257 +m = n
1258 claim.pick(~A, ~penc, ~target, ~work, m, now, pick(~A, p, s, now), j, s, c, ib, fs, (r2 => claim(~A, ~penc, ~target, ~work, m, now, r2)))
1259
1260def settle.done(-A: Data, y: Ran(A), g: Res.Grant, err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1261 (r, res) = y
1262 next(release(A, r, g), first(err, res))
1263
1264def settle.br(~A: Data, ~penc: A -> Bytes.Bytes, +op: Op<A>, y: Ran(A), g: Res.Grant, err: Out(Unit),
1265 next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1266 match y:
1267 case (r, Fail{e}):
1268 next(release(A, r, g), first(err, Fail{e}))
1269 case (r, Done{u}):
1270 do IO<Runner<A> & Out(Bool)>:
1271 z : Ran(A) <- commit(~A, ~penc, r, op)
1272 settle.done(A, z, g, err, next)
1273
1274# Tells the target's breaker, appends the outcome's op, and returns the attempt's unit to the pool.
1275# The op of a cancelled ticket changes no state: the queue no longer holds it.
1276def settle.op(~A: Data, ~penc: A -> Bytes.Bytes, +o: Retry.Outcome, b: Retry.Budget, +id: Nat, +key: String, +now: Nat, +rnd: Nat, r: Runner<A>, g: Res.Grant,
1277 err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1278 Runner{j, +s, p, +c, ib, fs} = r
1279 Config{pol, circ, idle, every} = c
1280 +old = brk.get(A, s, key)
1281 do IO<Runner<A> & Out(Bool)>:
1282 y : Ran(A) <- trip(~A, ~penc, Runner{j, s, p, c, ib, fs}, key, old, Retry.Breaker.done(Retry.BreakerOn{circ, old}, now, Retry.failed(o)))
1283 settle.br(~A, ~penc, after(A, o, pol, b, id, fails(tries.get(tries(A, s), id)), now, rnd), y, g, err, next)
1284
1285def random(r: Out(U32)) -> Nat:
1286 match r:
1287 case Done{x}:
1288 U32.to_nat(x)
1289 case Fail{e}:
1290 0n
1291
1292def take.keep(-A: Data, m: Maybe<&1, Flight<A>>, xs: List<&1, Flight<A>>) -> List<&1, Flight<A>>:
1293 match m:
1294 case None{}:
1295 xs
1296 case Some{f}:
1297 Con{f, xs}
1298
1299def take.at(-A: Data, eq: Bool, f: Flight<A>, r: Maybe<&1, Flight<A>> & List<&1, Flight<A>>) -> Maybe<&1, Flight<A>> & List<&1, Flight<A>>:
1300 match eq:
1301 case True{}:
1302 (m, xs) = r
1303 (Some{f}, take.keep(A, m, xs))
1304 case False{}:
1305 (m, xs) = r
1306 (m, Con{f, xs})
1307
1308# The flight of ticket id, and the other flights.
1309def take(-A: Data, fs: List<&1, Flight<A>>, +id: Nat) -> Maybe<&1, Flight<A>> & List<&1, Flight<A>>:
1310 match fs:
1311 case Nil{}:
1312 (None{}, Nil{})
1313 case Con{Flight{Q.Ticket{+i, d, x}, g, b, k}, rest}:
1314 take.at(A, Nat.is_eq(i, id), Flight{Q.Ticket{i, d, x}, g, b, k}, take(A, rest, id))
1315
1316def settle.flight(~A: Data, ~penc: A -> Bytes.Bytes, mf: Maybe<&1, Flight<A>>, +o: Retry.Outcome, +now: Nat, +rnd: Nat, r: Runner<A>, err: Out(Unit),
1317 next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1318 match mf:
1319 case None{}:
1320 next(r, err)
1321 case Some{Flight{Q.Ticket{id, d, x}, g, b, key}}:
1322 settle.op(~A, ~penc, o, b, id, key, now, rnd, r, g, err, next)
1323
1324def settle.take(~A: Data, ~penc: A -> Bytes.Bytes, t: Maybe<&1, Flight<A>> & List<&1, Flight<A>>, +o: Retry.Outcome, +now: Nat, +rnd: Nat,
1325 j: Log, s: State<A>, p: Res.Pool, c: Config, ib: Chan(Msg<A>), err: Out(Unit),
1326 next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1327 (mf, fs) = t
1328 settle.flight(~A, ~penc, mf, o, now, rnd, Runner{j, s, p, c, ib, fs}, err, next)
1329
1330# Settles the flight of ticket id with outcome o.
1331def settle(~A: Data, ~penc: A -> Bytes.Bytes, +id: Nat, +o: Retry.Outcome, +now: Nat, +rnd: Nat, r: Runner<A>, err: Out(Unit),
1332 next: Runner<A> -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1333 Runner{j, s, p, c, ib, fs} = r
1334 settle.take(~A, ~penc, take(A, fs, id), o, now, rnd, j, s, p, c, ib, err, next)
1335
1336# Sends the failure to the asker, and keeps it as the round's error.
1337def asked.failed(-A: Data, -X: Type, +rep: Chan(Out(X)), r: Runner<A>, +c: U32, +m: String, err: Out(Unit),
1338 next: Runner<A> -> Nat -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1339 do IO<Runner<A> & Out(Bool)>:
1340 x : Result<&1, &1, Out(X), Unit> <- Chan.send(Out(X), rep, Fail{(c, m)})
1341 next(r, 0n, first(err, Fail{(c, m)}))
1342
1343def asked.fail(-A: Data, -X: Type, +rep: Chan(Out(X)), r: Runner<A>, e: U32 & String, err: Out(Unit),
1344 next: Runner<A> -> Nat -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1345 (c, m) = e
1346 asked.failed(A, X, rep, r, c, m, err, next)
1347
1348def added(-A: Data, +rep: Chan(Out(Nat)), y: Runner<A> & Out(Nat), err: Out(Unit),
1349 next: Runner<A> -> Nat -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1350 match y:
1351 case (r, Done{+i}):
1352 do IO<Runner<A> & Out(Bool)>:
1353 x : Result<&1, &1, Out(Nat), Unit> <- Chan.send(Out(Nat), rep, Done{i})
1354 next(r, 1n, err)
1355 case (r, Fail{e}):
1356 asked.fail(A, Nat, rep, r, e, err, next)
1357
1358def dropped(-A: Data, +rep: Chan(Out(Unit)), y: Ran(A), err: Out(Unit),
1359 next: Runner<A> -> Nat -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1360 match y:
1361 case (r, Done{u}):
1362 do IO<Runner<A> & Out(Bool)>:
1363 x : Result<&1, &1, Out(Unit), Unit> <- Chan.send(Out(Unit), rep, Done{Unit{}})
1364 next(r, 0n, err)
1365 case (r, Fail{e}):
1366 asked.fail(A, Unit, rep, r, e, err, next)
1367
1368# Settles an ended attempt, or appends an ask's op and answers it. next gets the claim fuel the message adds: 1 for an enqueue.
1369def handle(~A: Data, ~penc: A -> Bytes.Bytes, m: Msg<A>, +now: Nat, +rnd: Nat, r: Runner<A>, err: Out(Unit),
1370 next: Runner<A> -> Nat -> Out(Unit) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1371 match m:
1372 case Ended{+id, +o}:
1373 settle(~A, ~penc, id, o, now, rnd, r, err, (r2 => e2 => next(r2, 0n, e2)))
1374 case Add{+d, x, +rep}:
1375 IO.bind(Runner<A> & Out(Nat), Runner<A> & Out(Bool), enqueue(~A, ~penc, r, d, x), y => added(A, rep, y, err, next))
1376 case Drop{+i, +rep}:
1377 IO.bind(Ran(A), Runner<A> & Out(Bool), cancel(~A, ~penc, r, i), y => dropped(A, rep, y, err, next))
1378
1379def merged(-A: Data, e: Out(Unit), k: Claimed(A)) -> Claimed(A):
1380 (r, n, err) = k
1381 (r, n, first(e, err))
1382
1383def empty.heap(-A: Data, h: H.Heap<Q.Ticket<A>>) -> Bool:
1384 match h:
1385 case H.HLeaf{}:
1386 True{}
1387 case H.HNode{n, t, l, r}:
1388 False{}
1389
1390def empty.list(-A: Data, xs: List<&2, Q.Ticket<A>>) -> Bool:
1391 match xs:
1392 case Nil{}:
1393 True{}
1394 case Con{t, rest}:
1395 False{}
1396
1397# No ticket is pending or running. Dead tickets wait for a Revive, so they do not count.
1398def idle(-A: Data, s: State<A>) -> Bool:
1399 State{Q.State{n, h, run}, ts, ds, bs} = s
1400 Bool.and(empty.heap(A, h), empty.list(A, run))
1401
1402def pending(-A: Data, s: State<A>) -> Nat:
1403 State{Q.State{n, h, run}, ts, ds, bs} = s
1404 H.Heap.size(Q.Ticket<A>, h)
1405
1406# The flights back, and whether none runs.
1407def flights.none(-A: Data, fs: List<&1, Flight<A>>) -> List<&1, Flight<A>> & Bool:
1408 match fs:
1409 case Nil{}:
1410 (Nil{}, True{})
1411 case Con{f, rest}:
1412 (Con{f, rest}, False{})
1413
1414# ---- compaction
1415
1416# Kept: compaction failed before the rename, and the old journal stands.
1417# Lost: the rename happened, but the new journal did not open. Moved: the journal at path is the snapshot.
1418type Swap is Type:
1419 Kept{err: U32 & String}
1420 Lost{err: U32 & String}
1421 Moved{journal: J.Journal}
1422
1423def swap.reopened(x: Out(J.Journal & Unit)) -> Swap:
1424 match x:
1425 case Fail{e}:
1426 Lost{e}
1427 case Done{(j, u)}:
1428 Moved{j}
1429
1430# The reopen fsyncs the directory, so the rename is durable before the next append.
1431def swap.renamed(+path: String, +limit: U32, x: Out(Unit)) -> IO(Swap):
1432 match x:
1433 case Fail{e}:
1434 IO.pure(Swap, Kept{e})
1435 case Done{u}:
1436 do IO<Swap>:
1437 y : Out(J.Journal & Unit) <- J.open(~Unit, ~(a => b => a), path, limit, limit, Unit{})
1438 return swap.reopened(y)
1439
1440def swap.written(+path: String, +tmp: String, +limit: U32, x: J.Journal & Out(Unit)) -> IO(Swap):
1441 match x:
1442 case (t, Fail{e}):
1443 do IO<Swap>:
1444 J.close(t)
1445 return Kept{e}
1446 case (t, Done{u}):
1447 do IO<Swap>:
1448 J.close(t)
1449 y : Out(Unit) <- Files.rename(tmp, path)
1450 swap.renamed(path, limit, y)
1451
1452def swap.opened(+path: String, +tmp: String, +limit: U32, x: Out(J.Journal & Unit), snap: Bytes.Bytes) -> IO(Swap):
1453 match x:
1454 case Fail{e}:
1455 IO.pure(Swap, Kept{e})
1456 case Done{(t, u)}:
1457 do IO<Swap>:
1458 y : J.Journal & Out(Unit) <- J.append(t, snap)
1459 swap.written(path, tmp, limit, y)
1460
1461# Writes snap as the only record of path.compact, fsyncs it, and renames it over path.
1462def swap(+path: String, +limit: U32, snap: Bytes.Bytes) -> IO(Swap):
1463 +tmp = path ++ ".compact"
1464 do IO<Swap>:
1465 gone : Out(Unit) <- Files.remove(tmp)
1466 x : Out(J.Journal & Unit) <- J.open(~Unit, ~(a => b => a), tmp, limit, limit, Unit{})
1467 swap.opened(path, tmp, limit, x, snap)
1468
1469def log.stop(j: J.Journal) -> J.Journal:
1470 J.Journal{file, max, end, ok} = j
1471 J.Journal{file, max, end, False{}}
1472
1473def compact.moved(x: Swap, j: J.Journal, +max: U32, path: String, +limit: U32, +base: U32) -> IO(Log & Out(Unit)):
1474 match x:
1475 case Kept{e}:
1476 IO.pure(Log & Out(Unit), (Log{j, path, limit, base}, Fail{e}))
1477 case Lost{e}:
1478 IO.pure(Log & Out(Unit), (Log{log.stop(j), path, limit, base}, Fail{e}))
1479 case Moved{k}:
1480 do IO<Log & Out(Unit)>:
1481 J.close(j)
1482 return (log.of(k, max, path, limit), Done{Unit{}})
1483
1484def compact.if(~A: Data, ~penc: A -> Bytes.Bytes, ok: Bool, j: J.Journal, +max: U32, +path: String, +limit: U32, +base: U32, s: State<A>) -> IO(Log & Out(Unit)):
1485 match ok:
1486 case False{}:
1487 IO.pure(Log & Out(Unit), (Log{j, path, limit, base}, Fail{(5, "runner: an append failed; reopen the runner")}))
1488 case True{}:
1489 do IO<Log & Out(Unit)>:
1490 x : Swap <- swap(path, limit, encode.snap(~A, ~penc, s))
1491 compact.moved(x, j, max, path, limit, base)
1492
1493def compact.done(-A: Data, x: Log & Out(Unit), s: State<A>, p: Res.Pool, c: Config, ib: Chan(Msg<A>), fs: List<&1, Flight<A>>) -> Ran(A):
1494 (l, o) = x
1495 (Runner{l, s, p, c, ib, fs}, o)
1496
1497# Writes the state as one Snap record into a new journal, fsyncs it, and renames it over the old one.
1498# A crash leaves one of the two journals, and both replay to this state. After a failure the old
1499# journal stands; when the failure came after the rename, appends stop until the runner is reopened.
1500def compact(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>) -> IO(Ran(A)):
1501 Runner{Log{j, path, limit, base}, +s, p, c, ib, fs} = r
1502 J.Journal{file, +max, end, +ok} = j
1503 do IO<Ran(A)>:
1504 x : Log & Out(Unit) <- compact.if(~A, ~penc, ok, J.Journal{file, max, end, ok}, max, path, limit, base, s)
1505 return compact.done(A, x, s, p, c, ib, fs)
1506
1507def tick.ran(e: Out(Unit), b: Bool) -> Out(Bool):
1508 match e:
1509 case Fail{x}:
1510 Fail{x}
1511 case Done{u}:
1512 Done{b}
1513
1514def tick.compacted(-A: Data, +b: Bool, y: Ran(A)) -> Runner<A> & Out(Bool):
1515 (r, e) = y
1516 (r, tick.ran(e, b))
1517
1518def tick.due(~A: Data, ~penc: A -> Bytes.Bytes, due: Bool, +b: Bool, r: Runner<A>) -> IO(Runner<A> & Out(Bool)):
1519 match due:
1520 case False{}:
1521 IO.pure(Runner<A> & Out(Bool), (r, Done{b}))
1522 case True{}:
1523 do IO<Runner<A> & Out(Bool)>:
1524 y : Ran(A) <- compact(~A, ~penc, r)
1525 return tick.compacted(A, b, y)
1526
1527def tick.size(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +b: Bool) -> IO(Runner<A> & Out(Bool)):
1528 Runner{Log{J.Journal{file, max, +end, ok}, path, limit, +base}, s, p, +c, ib, fs} = r
1529 Config{pol, circ, idle, +every} = c
1530 tick.due(~A, ~penc, Bool.and(Bool.not(U32.is_eq(every, 0)), U32.is_gt((end - base : U32), every)), b,
1531 Runner{Log{J.Journal{file, max, end, ok}, path, limit, base}, s, p, c, ib, fs})
1532
1533# Compacts once the journal grew past Config.compact octets since open or the last compaction.
1534def tick.grown(~A: Data, ~penc: A -> Bytes.Bytes, t: Runner<A> & Out(Bool)) -> IO(Runner<A> & Out(Bool)):
1535 match t:
1536 case (r, Fail{e}):
1537 IO.pure(Runner<A> & Out(Bool), (r, Fail{e}))
1538 case (r, Done{b}):
1539 tick.size(~A, ~penc, r, b)
1540
1541def tick.polled(-A: Data, x: Poll<&1, &1, Maybe<&1, Msg<A>>, Unit>) -> Maybe<&1, Msg<A>>:
1542 match x:
1543 case Ready{m}:
1544 m
1545 case Wait{u}:
1546 None{}
1547
1548def tick.wait(-A: Data, t: List<&1, Flight<A>> & Bool, j: Log, s: State<A>, p: Res.Pool, c: Config, +ib: Chan(Msg<A>)) ->
1549 IO(Runner<A> & Maybe<&1, Msg<A>>):
1550 (fs, none) = t
1551 match none:
1552 case False{}:
1553 do IO<Runner<A> & Maybe<&1, Msg<A>>>:
1554 m : Maybe<&1, Msg<A>> <- Chan.recv(Msg<A>, ib)
1555 return (Runner{j, s, p, c, ib, fs}, m)
1556 case True{}:
1557 do IO<Runner<A> & Maybe<&1, Msg<A>>>:
1558 x : Poll<&1, &1, Maybe<&1, Msg<A>>, Unit> <- Chan.try_recv(Msg<A>, ib, 0)
1559 return (Runner{j, s, p, c, ib, fs}, tick.polled(A, x))
1560
1561# The next message. While an attempt runs, it waits for one; when none runs, it takes one only when the inbox holds one.
1562def tick.next(-A: Data, r: Runner<A>) -> IO(Runner<A> & Maybe<&1, Msg<A>>):
1563 Runner{j, s, p, c, ib, fs} = r
1564 tick.wait(A, flights.none(A, fs), j, s, p, c, ib)
1565
1566# Handles the message, then claims due tickets into free units with the claim fuel left. None ends the round.
1567def tick.got(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), x: Runner<A> & Maybe<&1, Msg<A>>, +ran: Bool, +left: Nat,
1568 err: Out(Unit), next: Claimed(A) -> IO(Runner<A> & Out(Bool))) -> IO(Runner<A> & Out(Bool)):
1569 (r, m) = x
1570 match m:
1571 case None{}:
1572 IO.pure(Runner<A> & Out(Bool), (r, tick.ran(err, ran)))
1573 case Some{msg}:
1574 do IO<Runner<A> & Out(Bool)>:
1575 +now : Nat <- clock()
1576 rnd : Out(U32) <- IO.random_u32()
1577 handle(~A, ~penc, msg, now, random(rnd), r, err, (r2 => more => e2 =>
1578 IO.bind(Claimed(A), Runner<A> & Out(Bool), claim(~A, ~penc, ~target, ~work, Nat.add(left, more), now, r2), k2 => next(merged(A, e2, k2)))))
1579
1580# Handles messages until no attempt runs and the inbox is empty. fuel bounds the messages; attempts that still run
1581# when it ends stay in the runner, and the next tick settles them.
1582def tick.run(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), fuel: Nat, +ran: Bool, k: Claimed(A)) ->
1583 IO(Runner<A> & Out(Bool)):
1584 match fuel:
1585 case 0n:
1586 (r, left, err) = k
1587 IO.pure(Runner<A> & Out(Bool), (r, tick.ran(err, ran)))
1588 case 1n+n:
1589 (r, +left, err) = k
1590 do IO<Runner<A> & Out(Bool)>:
1591 x : Runner<A> & Maybe<&1, Msg<A>> <- tick.next(A, r)
1592 tick.got(~A, ~penc, ~target, ~work, x, ran, left, err, (k2 => tick.run(~A, ~penc, ~target, ~work, n, True{}, k2)))
1593
1594# Fuel for each pending ticket, each attempt that may already run, and the last look at the inbox.
1595def tick.at(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +now: Nat, r: Runner<A>) -> IO(Runner<A> & Out(Bool)):
1596 Runner{j, +s, +p, c, ib, fs} = r
1597 +fuel = Nat.add(2n, Nat.add(pending(A, s), Res.capacity(p)))
1598 do IO<Runner<A> & Out(Bool)>:
1599 k : Claimed(A) <- claim(~A, ~penc, ~target, ~work, fuel, now, Runner{j, s, p, c, ib, fs})
1600 tick.run(~A, ~penc, ~target, ~work, fuel, False{}, k)
1601
1602# One round: start an attempt for each due ticket the pool admits. Then read the inbox: as each attempt finishes, record its outcome,
1603# return its unit, and start the next due ticket in that unit; append and answer each ask from another fiber.
1604# The round ends when no attempt runs and the inbox is empty. Then compact the journal when it grew past Config.compact.
1605# Done{True} when an attempt ran or an ask was answered. work runs on its own; target names the breaker that guards it.
1606def tick(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), r: Runner<A>) -> IO(Runner<A> & Out(Bool)):
1607 do IO<Runner<A> & Out(Bool)>:
1608 now : Nat <- clock()
1609 t : Runner<A> & Out(Bool) <- tick.at(~A, ~penc, ~target, ~work, now, r)
1610 tick.grown(~A, ~penc, t)
1611
1612def finished.of(-A: Data, +quiet: Bool, t: List<&1, Flight<A>> & Bool, j: Log, s: State<A>, p: Res.Pool, c: Config, ib: Chan(Msg<A>)) ->
1613 Runner<A> & Bool:
1614 (fs, none) = t
1615 (Runner{j, s, p, c, ib, fs}, Bool.and(quiet, none))
1616
1617# The runner back, and whether no ticket is pending or running and no attempt runs.
1618def finished(-A: Data, r: Runner<A>) -> Runner<A> & Bool:
1619 Runner{j, +s, p, c, ib, fs} = r
1620 finished.of(A, idle(A, s), flights.none(A, fs), j, s, p, c, ib)
1621
1622def drain.handled(-A: Data, t: Runner<A> & Out(Bool), next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1623 match t:
1624 case (r, Fail{e}):
1625 IO.pure(Ran(A), (r, Fail{e}))
1626 case (r, Done{b}):
1627 next(r)
1628
1629def drain.woke(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +idle: U32,
1630 x: Poll<&1, &1, Maybe<&1, Msg<A>>, Unit>, r: Runner<A>, next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1631 match x:
1632 case Ready{Some{m}}:
1633 do IO<Ran(A)>:
1634 t : Runner<A> & Out(Bool) <- tick.got(~A, ~penc, ~target, ~work, (r, Some{m}), True{}, 0n, Done{Unit{}},
1635 (k => tick.run(~A, ~penc, ~target, ~work, 0n, True{}, k)))
1636 drain.handled(A, t, next)
1637 case Ready{None{}}:
1638 do IO<Ran(A)>:
1639 IO.sleep(idle)
1640 next(r)
1641 case Wait{u}:
1642 next(r)
1643
1644def drain.wait(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +idle: U32, r: Runner<A>,
1645 next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1646 Runner{j, s, p, c, +ib, fs} = r
1647 do IO<Ran(A)>:
1648 x : Poll<&1, &1, Maybe<&1, Msg<A>>, Unit> <- Chan.try_recv(Msg<A>, ib, idle)
1649 drain.woke(~A, ~penc, ~target, ~work, idle, x, Runner{j, s, p, c, ib, fs}, next)
1650
1651def drain.ticked(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +idle: U32,
1652 t: Runner<A> & Out(Bool), next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1653 match t:
1654 case (r, Fail{e}):
1655 IO.pure(Ran(A), (r, Fail{e}))
1656 case (r, Done{True{}}):
1657 next(r)
1658 case (r, Done{False{}}):
1659 drain.wait(~A, ~penc, ~target, ~work, idle, r, next)
1660
1661def drain.if(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), done: Bool, r: Runner<A>, next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1662 match done:
1663 case True{}:
1664 IO.pure(Ran(A), (r, Done{Unit{}}))
1665 case False{}:
1666 Runner{j, s, p, +c, ib, fs} = r
1667 Config{pol, circ, +idle, every} = c
1668 do IO<Ran(A)>:
1669 t : Runner<A> & Out(Bool) <- tick(~A, ~penc, ~target, ~work, Runner{j, s, p, c, ib, fs})
1670 drain.ticked(~A, ~penc, ~target, ~work, idle, t, next)
1671
1672def drain.at(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), x: Runner<A> & Bool, next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
1673 (r, done) = x
1674 drain.if(~A, ~penc, ~target, ~work, done, r, next)
1675
1676def drain.end(-A: Data, x: Runner<A> & Bool) -> Ran(A):
1677 (r, done) = x
1678 (r, Bool.pick(Out(Unit), done, Done{Unit{}}, Fail{(62, "runner: drain ran out of rounds")}))
1679
1680# Ticks until no ticket is pending or running and no attempt runs. After a round that did nothing, it waits up to idle ms
1681# for a message, and handles one that arrives at once.
1682# Fails when fuel rounds leave work.
1683def drain(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), fuel: Nat, r: Runner<A>) -> IO(Ran(A)):
1684 match fuel:
1685 case 0n:
1686 IO.pure(Ran(A), drain.end(A, finished(A, r)))
1687 case 1n+n:
1688 drain.at(~A, ~penc, ~target, ~work, finished(A, r), (r2 => drain(~A, ~penc, ~target, ~work, n, r2)))
1689
1690def orphans.next(-A: Data, y: Ran(A), err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
1691 (r, e) = y
1692 next(r, first(err, e))
1693
1694# A running ticket at open lost its attempt in a crash: it is requeued at now, as a failed attempt.
1695def orphans(~A: Data, ~penc: A -> Bytes.Bytes, ts: List<&2, Q.Ticket<A>>, +now: Nat, r: Runner<A>, err: Out(Unit)) -> IO(Ran(A)):
1696 match ts:
1697 case Nil{}:
1698 IO.pure(Ran(A), (r, err))
1699 case Con{Q.Ticket{id, d, x}, rest}:
1700 do IO<Ran(A)>:
1701 y : Ran(A) <- commit(~A, ~penc, r, Requeue{id, now})
1702 orphans.next(A, y, err, (r2 => e2 => orphans(~A, ~penc, rest, now, r2, e2)))
1703
1704def close.answer(-A: Data, m: Msg<A>) -> IO(Unit):
1705 match m:
1706 case Ended{id, o}:
1707 IO.pure(Unit, Unit{})
1708 case Add{d, x, rep}:
1709 do IO<Unit>:
1710 y : Result<&1, &1, Out(Nat), Unit> <- Chan.send(Out(Nat), rep, Fail{(32, "runner: the runner closed")})
1711 return Unit{}
1712 case Drop{i, rep}:
1713 do IO<Unit>:
1714 y : Result<&1, &1, Out(Unit), Unit> <- Chan.send(Out(Unit), rep, Fail{(32, "runner: the runner closed")})
1715 return Unit{}
1716
1717def close.polled(-A: Data, x: Poll<&1, &1, Maybe<&1, Msg<A>>, Unit>, next: Unit -> IO(Unit)) -> IO(Unit):
1718 match x:
1719 case Ready{Some{m}}:
1720 do IO<Unit>:
1721 close.answer(A, m)
1722 next(Unit{})
1723 case Ready{None{}}:
1724 IO.pure(Unit, Unit{})
1725 case Wait{u}:
1726 IO.pure(Unit, Unit{})
1727
1728# Answers each ask left in the closed inbox with a failure. fuel bounds the messages it reads.
1729def close.drain(-A: Data, fuel: Nat, +ib: Chan(Msg<A>)) -> IO(Unit):
1730 match fuel:
1731 case 0n:
1732 IO.pure(Unit, Unit{})
1733 case 1n+n:
1734 do IO<Unit>:
1735 x : Poll<&1, &1, Maybe<&1, Msg<A>>, Unit> <- Chan.try_recv(Msg<A>, ib, 0)
1736 close.polled(A, x, (u => close.drain(A, n, ib)))
1737
1738# Closes the inbox and the journal. Each ask still in the inbox gets a failure, and no op is appended for it.
1739def close(-A: Data, r: Runner<A>) -> IO(Unit):
1740 Runner{j, s, +p, c, +ib, fs} = r
1741 do IO<Unit>:
1742 Chan.close(Msg<A>, ib)
1743 close.drain(A, Nat.add(2n, Res.capacity(p)), ib)
1744 log.close(j)
1745
1746def open.done(-A: Data, y: Ran(A)) -> IO(Out(Runner<A>)):
1747 match y:
1748 case (r, Fail{e}):
1749 do IO<Out(Runner<A>)>:
1750 close(A, r)
1751 return Fail{e}
1752 case (r, Done{u}):
1753 IO.pure(Out(Runner<A>), Done{r})
1754
1755def open.got(~A: Data, ~penc: A -> Bytes.Bytes, x: Out(J.Journal & Maybe<&2, State<A>>), +max: U32, path: String, +limit: U32, c: Config, +capacity: Nat) ->
1756 IO(Out(Runner<A>)):
1757 match x:
1758 case Fail{e}:
1759 IO.pure(Out(Runner<A>), Fail{e})
1760 case Done{(j, None{})}:
1761 do IO<Out(Runner<A>)>:
1762 J.close(j)
1763 return Fail{(22, "runner: a journal record is not a runner record")}
1764 case Done{(j, Some{+s})}:
1765 do IO<Out(Runner<A>)>:
1766 now : Nat <- clock()
1767 ib : Chan(Msg<A>) <- Chan.new(Msg<A>, (U32.from_nat(capacity) + 1 : U32))
1768 y : Ran(A) <- orphans(~A, ~penc, Q.running(A, queue(A, s)), now, Runner{log.of(j, max, path, limit), calm(A, s), Res.new(0n, capacity), c, ib, Nil{}}, Done{Unit{}})
1769 open.done(A, y)
1770
1771def replay.step(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, acc: Maybe<&2, State<A>>, b: Bytes.Bytes) -> Maybe<&2, State<A>>:
1772 load(~A, ~Bytes.Bytes, ~(y => decode.rec(~A, ~pdec, y)), acc, b)
1773
1774# Opens the runner at path: replays its journal into the state, then requeues each ticket that was running.
1775# capacity bounds the attempts that run at once. max caps an op record's octets; limit caps the journal file and a snapshot.
1776# Fails when the journal fails to open, or a committed record is not a snapshot or an op.
1777def open(~A: Data, ~penc: A -> Bytes.Bytes, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +path: String, +max: U32, +limit: U32, c: Config, +capacity: Nat) -> IO(Out(Runner<A>)):
1778 do IO<Out(Runner<A>)>:
1779 x : Out(J.Journal & Maybe<&2, State<A>>) <- J.open(~Maybe<&2, State<A>>, ~(acc => b => replay.step(~A, ~pdec, acc, b)), path, limit, limit, Some{new(A)})
1780 open.got(~A, ~penc, x, max, path, limit, c, capacity)
1781
1782# The runner back, and a copy of its state.
1783def state(-A: Data, r: Runner<A>) -> Runner<A> & State<A>:
1784 Runner{j, +s, p, c, ib, fs} = r
1785 (Runner{j, s, p, c, ib, fs}, s)