runner.bend
bend-kit-runner@0.1.0.0 · 631 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
3# bend-kit-bytes@0.3.0.0, the version bend-kit-journal@0.1.0.0 takes, so J.append accepts these Bytes.
4import bend-kit-bytes@0.3.0.0/bytes.bend as Bytes
5import bend-kit-journal@0.1.0.0/journal.bend as J
6import bend-kit-scheduler@0.2.0.0/queue.bend as Q
7import bend-kit-resources@0.1.0.0/resources.bend as Res
8import bend-kit-retry@0.1.0.0/retry.bend as Retry
9import bend-kit-time@0.1.3.0/time.bend as Time
10import bend-kit-collections@0.1.2.0/heap.bend as H
11import bend-kit-collections@0.1.2.0/omap.bend as O
12
13# One queue transition. Each one is one journal record, appended before the state changes.
14# Select: the queue's select at now. Replay runs it at the same now, so it takes the same ticket.
15# Requeue: the attempt failed; it counts one failure. Defer: the breaker held the ticket back; no attempt ran.
16type Op<-A: Data> is Data:
17 Enqueue{deadline: Nat, payload: A}
18 Select{now: Nat}
19 Complete{id: Nat}
20 Cancel{id: Nat}
21 Requeue{id: Nat, deadline: Nat}
22 Defer{id: Nat, deadline: Nat}
23
24# The failed attempts of a ticket, and its first deadline, from which the policy deadline counts.
25type Try is Data:
26 Try{fails: Nat, start: Nat}
27
28# A Try for each ticket that is not yet complete or cancelled, by ticket id.
29def Tries() -> Data:
30 O.OMap<Nat, Try>
31
32# The durable state: the queue and the tries.
33type State<-A: Data> is Data:
34 State{queue: Q.State<A>, tries: Tries()}
35
36def new(-A: Data) -> State<A>:
37 State{Q.new(A), O.OMap.new(Nat, Try)}
38
39def queue(-A: Data, s: State<A>) -> Q.State<A>:
40 State{q, ts} = s
41 q
42
43def tries(-A: Data, s: State<A>) -> Tries():
44 State{q, ts} = s
45 ts
46
47# ---- tries
48
49def tries.drop(ts: Tries(), +i: Nat) -> Tries():
50 O.OMap.del(~Nat, ~Try, ~Nat.cmp, ts, i)
51
52def tries.get(ts: Tries(), +i: Nat) -> Maybe<&2, Try>:
53 O.OMap.get(~Nat, ~Try, ~Nat.cmp, ts, i)
54
55def tries.bump.got(m: Maybe<&2, Try>, ts: Tries(), +i: Nat) -> Tries():
56 match m:
57 case None{}:
58 ts
59 case Some{Try{f, st}}:
60 O.OMap.put(~Nat, ~Try, ~Nat.cmp, ts, i, Try{1n+f, st})
61
62def tries.bump(+ts: Tries(), +i: Nat) -> Tries():
63 tries.bump.got(tries.get(ts, i), ts, i)
64
65# ---- the transition
66
67def step.enqueued(-A: Data, r: Q.State<A> & Nat, ts: Tries(), d: Nat) -> State<A>:
68 (q, i) = r
69 State{q, O.OMap.put(~Nat, ~Try, ~Nat.cmp, ts, i, Try{0n, d})}
70
71def step.selected(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, ts: Tries()) -> State<A>:
72 (q, t) = r
73 State{q, ts}
74
75def step.requeued(-A: Data, r: Q.State<A> & Bool, ts: Tries()) -> State<A>:
76 (q, b) = r
77 State{q, ts}
78
79# Complete takes the ticket from the running list only: O(running), not O(pending).
80def step.completed(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, ts: Tries()) -> State<A>:
81 (q, t) = r
82 State{q, ts}
83
84# The state after op. Live and replay both run it, so they agree.
85def step(~A: Data, s: State<A>, op: Op<A>) -> State<A>:
86 match s op:
87 case State{q, ts} Enqueue{+d, x}:
88 step.enqueued(A, Q.enqueue(~A, d, x, q), ts, d)
89 case State{q, ts} Select{now}:
90 step.selected(A, Q.select(~A, now, q), ts)
91 case State{q, ts} Complete{+i}:
92 step.completed(A, Q.complete(A, i, q), tries.drop(ts, i))
93 case State{q, ts} Cancel{+i}:
94 State{Q.cancel(~A, i, q), tries.drop(ts, i)}
95 case State{q, ts} Requeue{+i, d}:
96 step.requeued(A, Q.requeue(~A, i, d, q), tries.bump(ts, i))
97 case State{q, ts} Defer{i, d}:
98 step.requeued(A, Q.requeue(~A, i, d, q), ts)
99
100def apply.op(~A: Data, m: Maybe<&2, Op<A>>, s: State<A>) -> Maybe<&2, State<A>>:
101 match m:
102 case None{}:
103 None{}
104 case Some{op}:
105 Some{step(~A, s, op)}
106
107# Folds one record into the replayed state. A record that does not decode ends the replay with None.
108def apply(~A: Data, ~R: Type, ~dec: R -> Maybe<&2, Op<A>>, acc: Maybe<&2, State<A>>, r: R) -> Maybe<&2, State<A>>:
109 match acc:
110 case None{}:
111 None{}
112 case Some{s}:
113 apply.op(~A, dec(r), s)
114
115# ---- pool
116
117# Picked: a due ticket and one unit of the pool for it. Idle: no due ticket, or no free unit; the pool is unchanged.
118type Pick<-A: Data> is Type:
119 Picked{pool: Res.Pool, ticket: Q.Ticket<A>, grant: Res.Grant}
120 Idle{pool: Res.Pool}
121
122def pick.took(-A: Data, r: Res.Reserve, t: Q.Ticket<A>) -> Pick<A>:
123 match r:
124 case Res.Took{p, g}:
125 Picked{p, t, g}
126 case Res.Refused{p}:
127 Idle{p}
128
129def pick.due(-A: Data, m: Maybe<&2, Q.Ticket<A>>, p: Res.Pool) -> Pick<A>:
130 match m:
131 case None{}:
132 Idle{p}
133 case Some{t}:
134 pick.took(A, Res.reserve(p, 1n), t)
135
136def pick.sel(-A: Data, r: Q.State<A> & Maybe<&2, Q.Ticket<A>>, p: Res.Pool) -> Pick<A>:
137 (q, m) = r
138 pick.due(A, m, p)
139
140# The ticket that Select{now} takes, with one unit of p, when there is a ticket due and a unit free.
141def pick(~A: Data, p: Res.Pool, s: State<A>, now: Nat) -> Pick<A>:
142 State{q, ts} = s
143 pick.sel(A, Q.select(~A, now, q), p)
144
145# ---- retry
146
147# The budget left for ticket i: the policy's attempts less its failures, until its start plus the policy deadline.
148def budget.of(+attempts: Nat, t: Maybe<&2, Try>, d: Maybe<&2, Nat>) -> Retry.Budget:
149 match t d:
150 case None{} m:
151 Retry.Budget{attempts, None{}}
152 case Some{Try{f, st}} None{}:
153 Retry.Budget{Nat.sub(attempts, f), None{}}
154 case Some{Try{f, +st}} Some{ms}:
155 Retry.Budget{Nat.sub(attempts, f), Some{Nat.add(st, ms)}}
156
157def budget(p: Retry.Policy, t: Maybe<&2, Try>) -> Retry.Budget:
158 Retry.Policy{a, base, cap, d} = p
159 budget.of(a, t, d)
160
161# The failures so far: the index of the next retry.
162def fails(t: Maybe<&2, Try>) -> Nat:
163 match t:
164 case None{}:
165 0n
166 case Some{Try{f, st}}:
167 f
168
169def after.plan(-A: Data, pl: Retry.Plan, +id: Nat, +now: Nat) -> Op<A>:
170 match pl:
171 case Retry.PlanStop{}:
172 Complete{id}
173 case Retry.PlanWait{w}:
174 Requeue{id, Nat.add(now, w)}
175
176# The record after an attempt of ticket id ends at now with o: requeue at now plus retry's wait, or complete.
177def after(-A: Data, o: Retry.Outcome, p: Retry.Policy, b: Retry.Budget, +id: Nat, +n: Nat, +now: Nat, +r: Nat) -> Op<A>:
178 after.plan(A, Retry.plan(o, p, b, n, now, r), id, now)
179
180# When an open breaker lets attempts start again.
181def until(br: Retry.Breaker, +now: Nat) -> Nat:
182 match br:
183 case Retry.BreakerOn{c, Retry.CircuitOpen{u}}:
184 u
185 case Retry.BreakerOn{c, Retry.CircuitClosed{fs}}:
186 Nat.add(now, Retry.Circuit.cooldown(c))
187 case Retry.BreakerOn{c, Retry.CircuitHalf{k}}:
188 Nat.add(now, Retry.Circuit.cooldown(c))
189 case Retry.BreakerOff{}:
190 now
191
192# The record for a ticket that admit refused: Defer to when the breaker may admit, or Complete when its budget is spent or late.
193def held(-A: Data, why: Retry.Deny, br: Retry.Breaker, +id: Nat, +now: Nat) -> Op<A>:
194 match why:
195 case Retry.DenyOpen{}:
196 Defer{id, until(br, now)}
197 case Retry.DenyLate{}:
198 Complete{id}
199 case Retry.DenySpent{}:
200 Complete{id}
201
202# ---- the record codec: a u32le tag, then u64le fields; an Enqueue then holds the payload.
203
204def W() -> Nat:
205 Nat.mul(65536n, 65536n)
206
207# Nat fields hold values under 2^64.
208def put.u64(b: Bytes.Bytes, +at: U32, +n: Nat) -> Bytes.Bytes:
209 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())))
210
211def head(+tag: U32, +a: Nat, +c: Nat) -> Bytes.Bytes:
212 put.u64(put.u64(Bytes.set.u32le(Bytes.new(20), 0, tag), 4, a), 12, c)
213
214def encode(~A: Data, ~penc: A -> Bytes.Bytes, op: Op<A>) -> Bytes.Bytes:
215 match op:
216 case Enqueue{+d, x}:
217 Bytes.append(put.u64(Bytes.set.u32le(Bytes.new(12), 0, 1), 4, d), penc(x))
218 case Select{+now}:
219 head(2, now, 0n)
220 case Complete{+i}:
221 head(3, i, 0n)
222 case Cancel{+i}:
223 head(4, i, 0n)
224 case Requeue{+i, +d}:
225 head(5, i, d)
226 case Defer{+i, +d}:
227 head(6, i, d)
228
229def get.field(m: Maybe<&2, U32>) -> U32:
230 match m:
231 case None{}:
232 0
233 case Some{x}:
234 x
235
236def get.u32(r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & U32:
237 (b, m) = r
238 (b, get.field(m))
239
240def get.hi(+lo: U32, r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & Nat:
241 (b, m) = r
242 (b, Nat.add(U32.to_nat(lo), Nat.mul(U32.to_nat(get.field(m)), W())))
243
244def get.lo(+at: U32, r: Bytes.Bytes & Maybe<&2, U32>) -> Bytes.Bytes & Nat:
245 (b, m) = r
246 +lo = get.field(m)
247 get.hi(lo, Bytes.get.u32le(b, (at + 4 : U32)))
248
249def get.u64(b: Bytes.Bytes, +at: U32) -> Bytes.Bytes & Nat:
250 get.lo(at, Bytes.get.u32le(b, at))
251
252def decode.small(-A: Data, ok: Bool, +tag: U32, +a: Nat, +c: Nat) -> Maybe<&2, Op<A>>:
253 match ok:
254 case False{}:
255 None{}
256 case True{}:
257 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 2), Some{Select{a}},
258 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 3), Some{Complete{a}},
259 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 4), Some{Cancel{a}},
260 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 5), Some{Requeue{a, c}},
261 Bool.pick(Maybe<&2, Op<A>>, U32.is_eq(tag, 6), Some{Defer{a, c}}, None{})))))
262
263def decode.payload(-A: Data, m: Maybe<&2, A>, +d: Nat) -> Maybe<&2, Op<A>>:
264 match m:
265 case None{}:
266 None{}
267 case Some{x}:
268 Some{Enqueue{d, x}}
269
270def decode.c(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +tag: U32, +len: U32, +a: Nat, r: Bytes.Bytes & Nat) -> Maybe<&2, Op<A>>:
271 (b, +c) = r
272 decode.small(A, U32.is_eq(len, 20), tag, a, c)
273
274def 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>>:
275 match enq:
276 case True{}:
277 decode.payload(A, pdec(Bytes.snd(Bytes.slice(b, 12, (len - 12 : U32)))), a)
278 case False{}:
279 decode.c(~A, ~pdec, tag, len, a, get.u64(b, 12))
280
281def decode.a(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +tag: U32, +len: U32, r: Bytes.Bytes & Nat) -> Maybe<&2, Op<A>>:
282 (b, +a) = r
283 decode.kind(~A, ~pdec, U32.is_eq(tag, 1), tag, len, a, b)
284
285def decode.tag(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, +len: U32, r: Bytes.Bytes & U32) -> Maybe<&2, Op<A>>:
286 (b, +tag) = r
287 decode.a(~A, ~pdec, tag, len, get.u64(b, 4))
288
289def decode.len(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, ok: Bool, +len: U32, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
290 match ok:
291 case False{}:
292 None{}
293 case True{}:
294 decode.tag(~A, ~pdec, len, get.u32(Bytes.get.u32le(b, 0)))
295
296# The op of a record, or None when it is not one that encode writes.
297def decode(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, b: Bytes.Bytes) -> Maybe<&2, Op<A>>:
298 Bytes.Bytes{+len, buf} = b
299 decode.len(~A, ~pdec, U32.is_ge(len, 12), len, Bytes.Bytes{len, buf})
300
301# ---- the runner
302
303# policy: retry's policy for each ticket. circuit: the breaker of each target. idle: ms that drain waits when no attempt started.
304type Config is Data:
305 Config{policy: Retry.Policy, circuit: Retry.Circuit, idle: U32}
306
307# An open runner. Its journal holds every op that made state; its pool bounds the attempts that run at once.
308type Runner<-A: Data> is Type:
309 Runner{journal: J.Journal, state: State<A>, pool: Res.Pool, breakers: Map<&2, Retry.Breaker>, config: Config}
310
311# An attempt that runs: its unit of the pool, the budget that admit left, its target, and the channel of its outcome.
312type Flight<-A: Data> is Type:
313 Flight{ticket: Q.Ticket<A>, grant: Res.Grant, budget: Retry.Budget, target: String, chan: Chan(Retry.Outcome)}
314
315def Out(-X: Type) -> Type:
316 Result<&1, &1, U32 & String, X>
317
318def Claimed(-A: Data) -> Type:
319 Runner<A> & List<&1, Flight<A>> & Out(Unit)
320
321def Ran(-A: Data) -> Type:
322 Runner<A> & Out(Unit)
323
324# Wall-clock ms since the Unix epoch. Deadlines must keep their meaning across a restart.
325def clock() -> IO(Nat):
326 do IO<Nat>:
327 t : Time.Instant <- Time.now()
328 return Time.Duration.to_ms_nat(Time.Instant.since_epoch(t))
329
330def first(a: Out(Unit), b: Out(Unit)) -> Out(Unit):
331 match a:
332 case Fail{e}:
333 Fail{e}
334 case Done{u}:
335 b
336
337def commit.done(~A: Data, x: J.Journal & Out(Unit), s: State<A>, +op: Op<A>, p: Res.Pool, bs: Map<&2, Retry.Breaker>, c: Config) -> Ran(A):
338 match x:
339 case (j, Done{u}):
340 (Runner{j, step(~A, s, op), p, bs, c}, Done{u})
341 case (j, Fail{e}):
342 (Runner{j, s, p, bs, c}, Fail{e})
343
344# Appends op, and applies it once the append is durable. After a failed append the state is as it was,
345# and the journal refuses every later append until the runner is reopened.
346def commit(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +op: Op<A>) -> IO(Ran(A)):
347 Runner{j, s, p, bs, c} = r
348 do IO<Ran(A)>:
349 x : J.Journal & Out(Unit) <- J.append(j, encode(~A, ~penc, op))
350 return commit.done(~A, x, s, op, p, bs, c)
351
352# A grant of this runner's pool always fits it, so Kept does not happen.
353def release.got(-A: Data, x: Res.Release, j: J.Journal, s: State<A>, bs: Map<&2, Retry.Breaker>, c: Config) -> Runner<A>:
354 match x:
355 case Res.Released{p}:
356 Runner{j, s, p, bs, c}
357 case Res.Kept{p, g}:
358 Runner{j, s, p, bs, c}
359
360def release(-A: Data, r: Runner<A>, g: Res.Grant) -> Runner<A>:
361 Runner{j, s, p, bs, c} = r
362 release.got(A, Res.release(p, g), j, s, bs, c)
363
364def claim.held(-A: Data, y: Ran(A), g: Res.Grant, fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
365 match y:
366 case (r, Fail{e}):
367 IO.pure(Claimed(A), (release(A, r, g), fs, Fail{e}))
368 case (r, Done{u}):
369 next(release(A, r, g), fs)
370
371def claim.go(~A: Data, ~penc: A -> Bytes.Bytes, ~work: A -> IO(Retry.Outcome), +now: Nat, a: Retry.Breaker & Retry.Budget & Retry.Gate, +key: String,
372 j: J.Journal, s: State<A>, p: Res.Pool, bs: Map<&2, Retry.Breaker>, c: Config, +id: Nat, d: Nat, +x: A, g: Res.Grant,
373 fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
374 match a:
375 case (+br, b, Retry.GateGo{}):
376 do IO<Claimed(A)>:
377 ch : Chan(Retry.Outcome) <- IO.fork(Retry.Outcome, work(x))
378 next(Runner{j, s, p, Map.set(&2, Retry.Breaker, bs, key, br), c}, Con{Flight{Q.Ticket{id, d, x}, g, b, key, ch}, fs})
379 case (+br, b, Retry.GateNo{why}):
380 do IO<Claimed(A)>:
381 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, Map.set(&2, Retry.Breaker, bs, key, br), c}, held(A, why, br, id, now))
382 claim.held(A, y, g, fs, next)
383
384def claim.gate(~A: Data, ~penc: A -> Bytes.Bytes, ~work: A -> IO(Retry.Outcome), +now: Nat, got: Map<&2, Retry.Breaker> & Retry.Breaker, +key: String,
385 j: J.Journal, +s: State<A>, p: Res.Pool, +c: Config, +id: Nat, d: Nat, +x: A, g: Res.Grant,
386 fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
387 (bs, br) = got
388 Config{pol, circ, idle} = c
389 claim.go(~A, ~penc, ~work, now, Retry.admit(br, budget(pol, tries.get(tries(A, s), id)), now), key, j, s, p, bs, c, id, d, x, g, fs, next)
390
391# The selected ticket asks its target's breaker and its own budget for an attempt.
392def 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,
393 fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
394 Runner{j, s, p, bs, +c} = r
395 Config{pol, circ, idle} = c
396 Q.Ticket{id, d, +x} = t
397 +key = target(x)
398 claim.gate(~A, ~penc, ~work, now, Map.get(Retry.Breaker, Retry.Breaker.new(circ), bs, key), key, j, s, p, c, id, d, x, g, fs, next)
399
400def claim.selected(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +now: Nat, y: Ran(A),
401 t: Q.Ticket<A>, g: Res.Grant, fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
402 match y:
403 case (r, Fail{e}):
404 IO.pure(Claimed(A), (release(A, r, g), fs, Fail{e}))
405 case (r, Done{u}):
406 claim.admit(~A, ~penc, ~target, ~work, now, r, t, g, fs, next)
407
408def claim.pick(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), +now: Nat, k: Pick<A>, j: J.Journal, s: State<A>,
409 bs: Map<&2, Retry.Breaker>, c: Config, fs: List<&1, Flight<A>>, next: Runner<A> -> List<&1, Flight<A>> -> IO(Claimed(A))) -> IO(Claimed(A)):
410 match k:
411 case Idle{p}:
412 IO.pure(Claimed(A), (Runner{j, s, p, bs, c}, fs, Done{Unit{}}))
413 case Picked{p, t, g}:
414 do IO<Claimed(A)>:
415 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, bs, c}, Select{now})
416 claim.selected(~A, ~penc, ~target, ~work, now, y, t, g, fs, next)
417
418# Starts an attempt for each due ticket while the pool has a free unit. fuel bounds the tickets taken.
419def claim(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), fuel: Nat, +now: Nat, r: Runner<A>, fs: List<&1, Flight<A>>) ->
420 IO(Claimed(A)):
421 match fuel:
422 case 0n:
423 IO.pure(Claimed(A), (r, fs, Done{Unit{}}))
424 case 1n+n:
425 Runner{j, +s, p, bs, c} = r
426 claim.pick(~A, ~penc, ~target, ~work, now, pick(~A, p, s, now), j, s, bs, c, fs, (r2 => fs2 => claim(~A, ~penc, ~target, ~work, n, now, r2, fs2)))
427
428def settle.done(-A: Data, y: Ran(A), g: Res.Grant, err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
429 (r, res) = y
430 next(release(A, r, g), first(err, res))
431
432def settle.br(~A: Data, ~penc: A -> Bytes.Bytes, +failed: Bool, +key: String, +now: Nat, got: Map<&2, Retry.Breaker> & Retry.Breaker, +op: Op<A>,
433 j: J.Journal, s: State<A>, p: Res.Pool, c: Config, g: Res.Grant, err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
434 (bs, br) = got
435 do IO<Ran(A)>:
436 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, Map.set(&2, Retry.Breaker, bs, key, Retry.Breaker.done(br, now, failed)), c}, op)
437 settle.done(A, y, g, err, next)
438
439def 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,
440 err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
441 Runner{j, +s, p, bs, +c} = r
442 Config{pol, circ, idle} = c
443 settle.br(~A, ~penc, Retry.failed(o), key, now, Map.get(Retry.Breaker, Retry.Breaker.new(circ), bs, key),
444 after(A, o, pol, b, id, fails(tries.get(tries(A, s), id)), now, rnd), j, s, p, c, g, err, next)
445
446def random(r: Out(U32)) -> Nat:
447 match r:
448 case Done{x}:
449 U32.to_nat(x)
450 case Fail{e}:
451 0n
452
453# Waits for the attempt, tells its target's breaker, appends Complete or Requeue, and returns its unit to the pool.
454def settle.one(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, f: Flight<A>, err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
455 Flight{Q.Ticket{id, d, x}, g, b, key, ch} = f
456 do IO<Ran(A)>:
457 o : Retry.Outcome <- IO.join(Retry.Outcome, ch)
458 now : Nat <- clock()
459 rnd : Out(U32) <- IO.random_u32()
460 settle.op(~A, ~penc, o, b, id, key, now, random(rnd), r, g, err, next)
461
462def settle(~A: Data, ~penc: A -> Bytes.Bytes, fs: List<&1, Flight<A>>, r: Runner<A>, err: Out(Unit)) -> IO(Ran(A)):
463 match fs:
464 case Nil{}:
465 IO.pure(Ran(A), (r, err))
466 case Con{f, rest}:
467 settle.one(~A, ~penc, r, f, err, (r2 => e2 => settle(~A, ~penc, rest, r2, e2)))
468
469def empty.heap(-A: Data, h: H.Heap<Q.Ticket<A>>) -> Bool:
470 match h:
471 case H.HLeaf{}:
472 True{}
473 case H.HNode{n, t, l, r}:
474 False{}
475
476def empty.list(-A: Data, xs: List<&2, Q.Ticket<A>>) -> Bool:
477 match xs:
478 case Nil{}:
479 True{}
480 case Con{t, rest}:
481 False{}
482
483# No ticket is pending or running.
484def idle(-A: Data, s: State<A>) -> Bool:
485 State{Q.State{n, h, run}, ts} = s
486 Bool.and(empty.heap(A, h), empty.list(A, run))
487
488def pending(-A: Data, s: State<A>) -> Nat:
489 State{Q.State{n, h, run}, ts} = s
490 H.Heap.size(Q.Ticket<A>, h)
491
492def tick.ran(e: Out(Unit), b: Bool) -> Out(Bool):
493 match e:
494 case Fail{x}:
495 Fail{x}
496 case Done{u}:
497 Done{b}
498
499def tick.done(-A: Data, y: Ran(A)) -> Runner<A> & Out(Bool):
500 (r, e) = y
501 (r, tick.ran(e, True{}))
502
503def tick.settle(~A: Data, ~penc: A -> Bytes.Bytes, c: Claimed(A)) -> IO(Runner<A> & Out(Bool)):
504 match c:
505 case (r, Nil{}, err):
506 IO.pure(Runner<A> & Out(Bool), (r, tick.ran(err, False{})))
507 case (r, Con{f, fs}, err):
508 do IO<Runner<A> & Out(Bool)>:
509 y : Ran(A) <- settle(~A, ~penc, Con{f, fs}, r, err)
510 return tick.done(A, y)
511
512def 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)):
513 Runner{j, +s, p, bs, c} = r
514 do IO<Runner<A> & Out(Bool)>:
515 k : Claimed(A) <- claim(~A, ~penc, ~target, ~work, 1n+pending(A, s), now, Runner{j, s, p, bs, c}, Nil{})
516 tick.settle(~A, ~penc, k)
517
518# One round: start an attempt for each due ticket the pool admits, wait for them all, and record each outcome.
519# Done{True} when an attempt ran. work runs on its own; target names the breaker that guards it.
520def tick(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), r: Runner<A>) -> IO(Runner<A> & Out(Bool)):
521 do IO<Runner<A> & Out(Bool)>:
522 now : Nat <- clock()
523 tick.at(~A, ~penc, ~target, ~work, now, r)
524
525def drain.ticked(-A: Data, +idle: U32, t: Runner<A> & Out(Bool), next: Runner<A> -> IO(Ran(A))) -> IO(Ran(A)):
526 match t:
527 case (r, Fail{e}):
528 IO.pure(Ran(A), (r, Fail{e}))
529 case (r, Done{True{}}):
530 next(r)
531 case (r, Done{False{}}):
532 do IO<Ran(A)>:
533 IO.sleep(idle)
534 next(r)
535
536def 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)):
537 match done:
538 case True{}:
539 IO.pure(Ran(A), (r, Done{Unit{}}))
540 case False{}:
541 Runner{j, s, p, bs, +c} = r
542 Config{pol, circ, +idle} = c
543 do IO<Ran(A)>:
544 t : Runner<A> & Out(Bool) <- tick(~A, ~penc, ~target, ~work, Runner{j, s, p, bs, c})
545 drain.ticked(A, idle, t, next)
546
547# Ticks until no ticket is pending or running. It waits idle ms after a round that started no attempt.
548# Fails when fuel rounds leave work.
549def drain(~A: Data, ~penc: A -> Bytes.Bytes, ~target: A -> String, ~work: A -> IO(Retry.Outcome), fuel: Nat, r: Runner<A>) -> IO(Ran(A)):
550 match fuel:
551 case 0n:
552 Runner{j, +s, p, bs, c} = r
553 IO.pure(Ran(A), (Runner{j, s, p, bs, c}, Bool.pick(Out(Unit), idle(A, s), Done{Unit{}}, Fail{(62, "runner: drain ran out of rounds")})))
554 case 1n+n:
555 Runner{j, +s, p, bs, c} = r
556 drain.if(~A, ~penc, ~target, ~work, idle(A, s), Runner{j, s, p, bs, c}, (r2 => drain(~A, ~penc, ~target, ~work, n, r2)))
557
558def orphans.next(-A: Data, y: Ran(A), err: Out(Unit), next: Runner<A> -> Out(Unit) -> IO(Ran(A))) -> IO(Ran(A)):
559 (r, e) = y
560 next(r, first(err, e))
561
562# A running ticket at open lost its attempt in a crash: it is requeued at now, as a failed attempt.
563def orphans(~A: Data, ~penc: A -> Bytes.Bytes, ts: List<&2, Q.Ticket<A>>, +now: Nat, r: Runner<A>, err: Out(Unit)) -> IO(Ran(A)):
564 match ts:
565 case Nil{}:
566 IO.pure(Ran(A), (r, err))
567 case Con{Q.Ticket{id, d, x}, rest}:
568 do IO<Ran(A)>:
569 y : Ran(A) <- commit(~A, ~penc, r, Requeue{id, now})
570 orphans.next(A, y, err, (r2 => e2 => orphans(~A, ~penc, rest, now, r2, e2)))
571
572def open.done(-A: Data, y: Ran(A)) -> IO(Out(Runner<A>)):
573 match y:
574 case (Runner{j, s, p, bs, c}, Fail{e}):
575 do IO<Out(Runner<A>)>:
576 J.close(j)
577 return Fail{e}
578 case (r, Done{u}):
579 IO.pure(Out(Runner<A>), Done{r})
580
581def open.got(~A: Data, ~penc: A -> Bytes.Bytes, x: Out(J.Journal & Maybe<&2, State<A>>), c: Config, +capacity: Nat) -> IO(Out(Runner<A>)):
582 match x:
583 case Fail{e}:
584 IO.pure(Out(Runner<A>), Fail{e})
585 case Done{(j, None{})}:
586 do IO<Out(Runner<A>)>:
587 J.close(j)
588 return Fail{(22, "runner: a journal record is not a runner op")}
589 case Done{(j, Some{+s})}:
590 do IO<Out(Runner<A>)>:
591 now : Nat <- clock()
592 y : Ran(A) <- orphans(~A, ~penc, Q.running(A, queue(A, s)), now, Runner{j, s, Res.new(0n, capacity), Map.new(&2, Retry.Breaker), c}, Done{Unit{}})
593 open.done(A, y)
594
595def replay.step(~A: Data, ~pdec: Bytes.Bytes -> Maybe<&2, A>, acc: Maybe<&2, State<A>>, b: Bytes.Bytes) -> Maybe<&2, State<A>>:
596 apply(~A, ~Bytes.Bytes, ~(y => decode(~A, ~pdec, y)), acc, b)
597
598# Opens the runner at path: replays its journal into the state, then requeues each ticket that was running.
599# capacity bounds the attempts that run at once. max caps a record's octets; limit caps the journal file.
600# Fails when the journal fails to open, or a committed record is not an op.
601def 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>)):
602 do IO<Out(Runner<A>)>:
603 x : Out(J.Journal & Maybe<&2, State<A>>) <- J.open(~Maybe<&2, State<A>>, ~(acc => b => replay.step(~A, ~pdec, acc, b)), path, max, limit, Some{new(A)})
604 open.got(~A, ~penc, x, c, capacity)
605
606def enqueue.done(-A: Data, +id: Nat, y: Ran(A)) -> Runner<A> & Out(Nat):
607 match y:
608 case (r, Done{u}):
609 (r, Done{id})
610 case (r, Fail{e}):
611 (r, Fail{e})
612
613# Adds a job that is due at deadline (wall-clock ms) and answers its ticket id once the record is durable.
614def enqueue(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +deadline: Nat, x: A) -> IO(Runner<A> & Out(Nat)):
615 Runner{j, +s, p, bs, c} = r
616 do IO<Runner<A> & Out(Nat)>:
617 y : Ran(A) <- commit(~A, ~penc, Runner{j, s, p, bs, c}, Enqueue{deadline, x})
618 return enqueue.done(A, Q.next_id(A, queue(A, s)), y)
619
620# Cancels ticket id. A running attempt finishes, but its ticket is never selected again.
621def cancel(~A: Data, ~penc: A -> Bytes.Bytes, r: Runner<A>, +id: Nat) -> IO(Ran(A)):
622 commit(~A, ~penc, r, Cancel{id})
623
624# The runner back, and a copy of its state.
625def state(-A: Data, r: Runner<A>) -> Runner<A> & State<A>:
626 Runner{j, +s, p, bs, c} = r
627 (Runner{j, s, p, bs, c}, s)
628
629def close(-A: Data, r: Runner<A>) -> IO(Unit):
630 Runner{j, s, p, bs, c} = r
631 J.close(j)