prns-core 0.3.7

Pure Reticulum engine and wire contract for Personal Reticulum
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
//! The deadline watchdog: silent rounds re-request and shrink the window, exhausted retry budgets fail the transfer, and every retired slot bequeaths its window and rate to the link.

use super::rounds::{expected_inflight_bits_per_second, shrink_window_after_silent_round};
#[cfg(feature = "runtime-metrics")]
use crate::engine::ResourceAdmissionEvent;
use crate::engine::{
    EngineReaction, EngineState, InstantMillis, Journaled, SendRequestFailure, Settlement,
};
use crate::routing::links::request::RequestId;
use crate::routing::links::resources::table::{
    IncomingResourceStatus, IncomingResourceStorageAdmission,
};
use crate::routing::links::resources::{ResourceCorrelation, ResourceFailureCause, ResourceHash};
use crate::routing::links::table::LinkPhase;
use crate::routing::links::LinkId;
use crate::storage::StorageLayout;

enum PendingOfferDueAction {
    Drop,
    Reject,
    RejectResponse {
        request_id: RequestId,
        failure: SendRequestFailure,
    },
}

impl<S: StorageLayout> EngineState<S> {
    pub(crate) fn pending_resource_deadline(&self) -> Option<InstantMillis> {
        self.pending_resource_offers
            .offers()
            .iter()
            .map(|offer| {
                if !matches!(
                    self.links.phase_for(&offer.link_id()),
                    Some(LinkPhase::Active { .. })
                ) {
                    return InstantMillis(0);
                }
                match self
                    .incoming_resources
                    .storage_admission_for(offer.accepted())
                {
                    IncomingResourceStorageAdmission::Available
                    | IncomingResourceStorageAdmission::Impossible
                    | IncomingResourceStorageAdmission::Malformed => InstantMillis(0),
                    IncomingResourceStorageAdmission::TemporarilyFull => {
                        self.pending_offer_effective_deadline(offer)
                    }
                }
            })
            .min()
    }

    fn pending_offer_effective_deadline(
        &self,
        offer: &crate::routing::links::resources::pending::PendingResourceOffer,
    ) -> InstantMillis {
        let wait_deadline = offer.wait_deadline();
        match offer.correlation() {
            ResourceCorrelation::Response(request_id) => self
                .receipts
                .pending_request_deadline(request_id)
                .map_or(InstantMillis(0), |request_deadline| {
                    wait_deadline.min(request_deadline)
                }),
            ResourceCorrelation::Request { .. } | ResourceCorrelation::Unsolicited => wait_deadline,
        }
    }

    fn fire_due_pending_resource_offers<F>(
        &mut self,
        now: InstantMillis,
        fill_entropy: &mut F,
        sink: &mut impl FnMut(EngineReaction<'_>),
    ) where
        F: FnMut(&mut [u8]),
    {
        loop {
            let due = self
                .pending_resource_offers
                .offers()
                .iter()
                .enumerate()
                .find_map(|(index, offer)| {
                    if !matches!(
                        self.links.phase_for(&offer.link_id()),
                        Some(LinkPhase::Active { .. })
                    ) {
                        return Some((index, PendingOfferDueAction::Drop));
                    }
                    let admission = self
                        .incoming_resources
                        .storage_admission_for(offer.accepted());
                    if admission == IncomingResourceStorageAdmission::Malformed {
                        return Some((index, PendingOfferDueAction::Drop));
                    }
                    let impossible = admission == IncomingResourceStorageAdmission::Impossible;
                    let wait_deadline = offer.wait_deadline();
                    match offer.correlation() {
                        ResourceCorrelation::Response(request_id) => {
                            let Some(request_deadline) =
                                self.receipts.pending_request_deadline(request_id)
                            else {
                                return Some((index, PendingOfferDueAction::Reject));
                            };
                            if !impossible && wait_deadline > now && request_deadline > now {
                                return None;
                            }
                            let failure =
                                if request_deadline <= now && request_deadline <= wait_deadline {
                                    SendRequestFailure::Timeout
                                } else {
                                    SendRequestFailure::ResourceCapacity
                                };
                            Some((
                                index,
                                PendingOfferDueAction::RejectResponse {
                                    request_id,
                                    failure,
                                },
                            ))
                        }
                        ResourceCorrelation::Request { .. } | ResourceCorrelation::Unsolicited => {
                            (impossible || wait_deadline <= now)
                                .then_some((index, PendingOfferDueAction::Reject))
                        }
                    }
                });
            let Some((index, action)) = due else {
                break;
            };
            let offer = self.pending_resource_offers.remove_at(index);
            #[cfg(feature = "runtime-metrics")]
            if matches!(
                &action,
                PendingOfferDueAction::Reject | PendingOfferDueAction::RejectResponse { .. }
            ) {
                if offer.wait_deadline() <= now
                    || matches!(
                        &action,
                        PendingOfferDueAction::RejectResponse {
                            failure: SendRequestFailure::Timeout,
                            ..
                        }
                    )
                {
                    self.record_resource_admission_event(ResourceAdmissionEvent::Expired);
                }
                self.record_resource_admission_event(ResourceAdmissionEvent::Rejected);
            }
            match action {
                PendingOfferDueAction::Drop => continue,
                PendingOfferDueAction::Reject => {
                    self.reject_offered_resource(
                        &offer.link_id(),
                        &offer.hash(),
                        now,
                        fill_entropy,
                        sink,
                    );
                }
                PendingOfferDueAction::RejectResponse {
                    request_id,
                    failure,
                } => {
                    self.reject_offered_resource(
                        &offer.link_id(),
                        &offer.hash(),
                        now,
                        fill_entropy,
                        sink,
                    );
                    let Some(receipt) = self.receipts.settle_by_request_id(request_id) else {
                        continue;
                    };
                    sink(EngineReaction::Journaled(Journaled::CommandSettled {
                        id: receipt.command_id,
                        settlement: Settlement::SendRequest(Err(failure)),
                    }));
                }
            }
        }

        loop {
            let incoming = &self.incoming_resources;
            let Some(offer) = self.pending_resource_offers.pop_oldest_fitting(|offer| {
                matches!(
                    incoming.storage_admission_for(offer.accepted()),
                    IncomingResourceStorageAdmission::Available
                )
            }) else {
                break;
            };
            let outcome = self.admit_accepted_resource(
                offer.link_id(),
                offer.original_hash(),
                offer.accepted(),
                offer.first_arrived_at(),
            );
            if let crate::routing::ingress::IngestPacketOutcome::OwesResourcePull {
                link_id,
                hash,
            } = outcome
            {
                #[cfg(feature = "runtime-metrics")]
                self.record_resource_admission_event(ResourceAdmissionEvent::Promoted);
                self.emit_resource_pull(&link_id, &hash, now, fill_entropy, sink);
            }
        }
    }

    /// RNS 1.4.2's watchdog TRANSFERRING branch. A receiver that gives up goes silent, like the reference; the sender discovers through its own watchdog.
    pub(crate) fn fire_due_incoming_resources<F>(
        &mut self,
        now: InstantMillis,
        fill_entropy: &mut F,
        sink: &mut impl FnMut(EngineReaction<'_>),
    ) where
        F: FnMut(&mut [u8]),
    {
        while let Some(index) = self.incoming_resources.due_index(now) {
            let link_id = *self.incoming_resources.link_at(index);
            let hash = *self.incoming_resources.hash_at(index);
            let state = *self.incoming_resources.state(index);
            let expired = if state.status == IncomingResourceStatus::AwaitingDecompression {
                Some(ResourceFailureCause::DecompressionTimedOut)
            } else if state.status == IncomingResourceStatus::AwaitingOpen {
                Some(ResourceFailureCause::OpenTimedOut)
            } else if self.links.phase_for(&link_id).is_none() {
                Some(ResourceFailureCause::LinkVanished)
            } else if state.retries_left == 0 {
                Some(ResourceFailureCause::RetriesExhausted)
            } else {
                None
            };
            if let Some(cause) = expired {
                self.fail_incoming_resource(&link_id, &hash, cause, sink);
                continue;
            }
            {
                let state = self.incoming_resources.state_mut(index);
                shrink_window_after_silent_round(state);
                state.waiting_for_hmu = false;
                state.outstanding_part_count = 0;
                state.retries_left -= 1;
            }
            self.emit_resource_pull(&link_id, &hash, now, fill_entropy, sink);
        }
    }

    /// RNS 1.4.2 `Link.resource_concluded` stores the final window and expected rate for the next transfer to inherit, however this one ended.
    pub(crate) fn retire_incoming_resource(&mut self, link_id: &LinkId, hash: &ResourceHash) {
        if let Some(index) = self.incoming_resources.lookup(link_id, hash) {
            let state = *self.incoming_resources.state(index);
            let link_rtt_ms = match self.links.phase_for(link_id) {
                Some(LinkPhase::Active { rtt, .. }) => rtt.millis(),
                _ => 1,
            };
            let eifr = expected_inflight_bits_per_second(&state, link_rtt_ms);
            self.links
                .note_resource_concluded(link_id, state.window, eifr);
        }
        self.incoming_resources.remove(link_id, hash);
    }

    pub fn fire_due_resource_deadlines<F>(
        &mut self,
        now: InstantMillis,
        fill_entropy: &mut F,
        sink: &mut impl FnMut(EngineReaction<'_>),
    ) -> crate::engine::WakeSchedules
    where
        F: FnMut(&mut [u8]),
    {
        self.fire_due_outgoing_resources(now, fill_entropy, sink);
        self.fire_due_incoming_resources(now, fill_entropy, sink);
        self.fire_due_pending_resource_offers(now, fill_entropy, sink);
        let mut wake_schedule_changes = crate::engine::WakeSchedules::UNCHANGED;
        wake_schedule_changes.resource_deadlines = self.resource_deadlines_wake();
        wake_schedule_changes.receipt_timeouts = self.receipt_timeouts_wake();
        wake_schedule_changes
    }
}

#[cfg(test)]
mod watchdog_tests {
    use super::*;
    use crate::engine::test_support::filled_frame;
    use crate::engine::Directive;
    use crate::engine::{Journaled, WakeSchedule};
    use crate::routing::links::resources::receive::tests_support::*;
    use crate::routing::links::resources::PART_REQUEST_MAX_RETRIES;

    struct WatchCapture {
        frames: usize,
        failed: std::vec::Vec<ResourceFailureCause>,
    }

    fn fire(
        engine: &mut EngineState<crate::engine::test_support::TestStorageLayout>,
        at: u64,
    ) -> WatchCapture {
        let mut capture = WatchCapture {
            frames: 0,
            failed: std::vec::Vec::new(),
        };
        engine.fire_due_resource_deadlines(
            InstantMillis(at),
            &mut |bytes: &mut [u8]| bytes.fill(0xF2),
            &mut |reaction| match reaction {
                EngineReaction::Directive(Directive::EmitFrame { fill, .. }) => {
                    if filled_frame(fill).is_some() {
                        capture.frames += 1;
                    }
                }
                EngineReaction::Journaled(Journaled::ResourceFailed { cause, .. }) => {
                    capture.failed.push(cause);
                }
                _ => {}
            },
        );
        capture
    }

    #[test]
    fn a_starved_pull_shrinks_its_window_and_asks_again() {
        let mut receiver = engine_with_active_link();
        accept_everything(&mut receiver);
        let pull = feed(
            &mut receiver,
            &advertisement_frame(&four_part_payload(), None),
            2_000,
        );
        assert_eq!(pull.frames.len(), 1);
        let bootstrap_eifr = 287 * 8_000 / 250;
        let unmeasured_wait = 4 * (464 * 8 * 3_000 / bootstrap_eifr);
        assert_eq!(
            receiver.resource_deadlines_wake(),
            WakeSchedule::At(InstantMillis(2_000 + unmeasured_wait + 250)),
            "an unmeasured pull waits three sdu of flight at the establishment-bootstrapped rate",
        );

        let retried = fire(&mut receiver, 2_000 + unmeasured_wait + 250);
        assert_eq!(retried.frames, 1, "the pull goes out again");
        let hash = *receiver.incoming_resources.hash_at(0);
        let index = receiver
            .incoming_resources
            .lookup(&link_id(), &hash)
            .unwrap();
        let state = receiver.incoming_resources.state(index);
        assert_eq!(state.window, 3, "the window eases down");
        assert_eq!(state.window_max, 8, "and its ceiling follows twice");
        assert_eq!(state.retries_left, 15);
        assert_eq!(
            receiver.resource_deadlines_wake(),
            WakeSchedule::At(InstantMillis(
                2_000 + unmeasured_wait + 250 + unmeasured_wait + 250 + 500,
            )),
            "the next deadline stretches by one per-retry delay",
        );
    }

    #[test]
    fn a_received_part_refills_the_retry_budget_like_the_reference() {
        let mut sender = engine_with_active_link();
        let mut receiver = engine_with_active_link();
        accept_everything(&mut receiver);
        let pull = feed(
            &mut receiver,
            &advertise_from(&mut sender, &four_part_payload(), None),
            2_000,
        );

        let bootstrap_eifr = 287 * 8_000 / 250;
        let unmeasured_wait = 4 * (464 * 8 * 3_000 / bootstrap_eifr);
        fire(&mut receiver, 2_000 + unmeasured_wait + 250);
        let hash = *receiver.incoming_resources.hash_at(0);
        let index = receiver
            .incoming_resources
            .lookup(&link_id(), &hash)
            .unwrap();
        assert_eq!(receiver.incoming_resources.state(index).retries_left, 15);

        let serve = feed(&mut sender, &pull.frames[0].1, 30_000);
        feed(&mut receiver, &serve.frames[0].1, 30_100);
        assert_eq!(
            receiver.incoming_resources.state(index).retries_left,
            PART_REQUEST_MAX_RETRIES,
            "a placed part refills the budget so only consecutive dead rounds exhaust it",
        );
    }

    #[test]
    fn a_receiver_out_of_retries_goes_silent_and_fails() {
        let mut receiver = engine_with_active_link();
        accept_everything(&mut receiver);
        feed(
            &mut receiver,
            &advertisement_frame(&four_part_payload(), None),
            2_000,
        );
        let hash = *receiver.incoming_resources.hash_at(0);
        let index = receiver
            .incoming_resources
            .lookup(&link_id(), &hash)
            .unwrap();
        receiver.incoming_resources.state_mut(index).retries_left = 0;

        let gave_up = fire(&mut receiver, 60_000);
        assert_eq!(
            gave_up.frames, 0,
            "giving up sends nothing, like the reference"
        );
        assert_eq!(gave_up.failed, [ResourceFailureCause::RetriesExhausted]);
        assert!(receiver.incoming_resources.is_empty());
        assert_eq!(receiver.resource_deadlines_wake(), WakeSchedule::Idle);
    }
}