src/coordinator/UnixSocketPolicy.bend

mylsm-lsm-store@0.6.0.1 · 63 lines · 11 definitions

1import Base
2
3# Distinguishes supported socket errors from missing host capabilities.
4type Classification is Data:
5  UnsupportedPlatform{}
6  Transient{code: U32}
7  Host{code: U32}
8
9# Carries the state for PollStatus.
10type PollStatus is Data:
11  Readable{}
12  ReadableFailed{}
13  Idle{}
14  Failed{}
15
16# Carries the state for PollFailureAction.
17type PollFailureAction is Data:
18  Retry{}
19  Stop{}
20
21def event.applies(connection_id: U32, event_id: U32) -> Bool:
22  U32.is_eq(connection_id, event_id)
23
24# Classifies platform-specific errno values without performing host IO.
25def classify_code(code: U32) -> Classification:
26  match code:
27    case 45: UnsupportedPlatform{}
28    case 78: UnsupportedPlatform{}
29    case 95: UnsupportedPlatform{}
30    case 38: UnsupportedPlatform{}
31    case 4: Transient{4}
32    case 11: Transient{11}
33    case 35: Transient{35}
34    case _: Host{code}
35
36def poll.failure.action(classification: Classification) -> PollFailureAction:
37  match classification:
38    case Transient{_}: Retry{}
39    case _: Stop{}
40
41def poll.failure(code: U32) -> PollFailureAction:
42  poll.failure.action(classify_code(code))
43
44def poll.failed(flags: U32) -> Bool:
45  Bool.not(U32.is_eq(U32.and(flags, 56), 0))
46
47def poll.readable(flags: U32) -> Bool:
48  Bool.not(U32.is_eq(U32.and(flags, 1), 0))
49
50def poll.status.readable(readable: Bool, failed: Bool) -> PollStatus:
51  match readable:
52    case True{}:
53      match failed:
54        case True{}: ReadableFailed{}
55        case False{}: Readable{}
56    case False{}:
57      match failed:
58        case True{}: Failed{}
59        case False{}: Idle{}
60
61# Handles poll status.
62def poll_status(+flags: U32) -> PollStatus:
63  poll.status.readable(poll.readable(flags), poll.failed(flags))