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| 1 | package activator |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "time" |
| 7 | ) |
| 8 | |
| 9 | // swapSettle is the canary's settle (spec §6.2, §7.5 step 4). A successor |
| 10 | // that passed its health check must then stay up this long before the |
| 11 | // switch. A var so tests can shrink it, like spawnHealthTimeout. |
| 12 | var swapSettle = 10 * time.Second |
| 13 | |
| 14 | var errSettleExit = errors.New("swap: successor exited during its settle") |
| 15 | |
| 16 | type settleResult int |
| 17 | |
| 18 | const ( |
| 19 | settleOK settleResult = iota // stayed up for the whole window |
| 20 | settleExited // died on its own: a failure of the build |
| 21 | settleCancelled // an intentional stop ended the observation |
| 22 | ) |
| 23 | |
| 24 | // observeSettle watches p for window after it became healthy (spec §6.2, |
| 25 | // §6.4). Cancellation wins over an exit seen at the same moment. The |
| 26 | // barrier cancels an attempt BEFORE anything is stopped, so a process that |
| 27 | // dies once a stop has begun died of the stop, not of its build. |
| 28 | func observeSettle(ctx context.Context, p Proc, window time.Duration) settleResult { |
| 29 | verdict := func() (settleResult, bool) { |
| 30 | if ctx.Err() != nil { |
| 31 | return settleCancelled, true |
| 32 | } |
| 33 | if p.Exited() { |
| 34 | return settleExited, true |
| 35 | } |
| 36 | return settleOK, false |
| 37 | } |
| 38 | if r, over := verdict(); over || window <= 0 { |
| 39 | return r |
| 40 | } |
| 41 | deadline := time.NewTimer(window) |
| 42 | defer deadline.Stop() |
| 43 | tick := time.NewTicker(settlePoll(window)) |
| 44 | defer tick.Stop() |
| 45 | for { |
| 46 | select { |
| 47 | case <-ctx.Done(): |
| 48 | return settleCancelled |
| 49 | case <-tick.C: |
| 50 | if r, over := verdict(); over { |
| 51 | return r |
| 52 | } |
| 53 | case <-deadline.C: |
| 54 | r, _ := verdict() |
| 55 | return r |
| 56 | } |
| 57 | } |
| 58 | } |
| 59 | |
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