| 1 | package activator |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | |
| 6 | "github.com/carlosframework/platform/internal/registry" |
| 7 | ) |
| 8 | |
| 9 | // PlannedSelection is the planner's checked choice of a build in place of |
| 10 | // another, for one exec (settings plan 4, ruling R-PLANNED-RECOVERY; zero- |
| 11 | // downtime spec §8.2): Build is the good build the plan boots instead of |
| 12 | // InPlaceOf. It is one of |
| 13 | // |
| 14 | // - a planned fallback: a first wake's B failed and was proven stopped, |
| 15 | // and the good build starts in its place (spawnPlanned, |
| 16 | // spawnPlannedWorker); |
| 17 | // - the good build booted untried, when too little of B's health window |
| 18 | // was left at its exec (spawnPlanned); |
| 19 | // - a recovery boot: decideWake planned the good build in place of the |
| 20 | // installed build, which the failure book blocks (settleWakeIdentity, |
| 21 | // spawnPlanned, a claimed start). |
| 22 | // |
| 23 | // The activator puts it on the context of that exec's record only, after |
| 24 | // the plan's selection gate (Check) passed for Build. The agent's pre-exec |
| 25 | // revalidation (release.HeldExecStale) admits Build when the state read under |
| 26 | // the lease holds InPlaceOf as the instance's target: the planner's reason |
| 27 | // for leaving InPlaceOf is then the reason the held target is left, as |
| 28 | // zero-downtime spec §6 and settings spec §6 require. The record is still |
| 29 | // written. It never admits the good build in general: a context with no |
| 30 | // selection, or one made in place of another build, is revalidated as |
| 31 | // before. |
| 32 | type PlannedSelection struct{ Build, InPlaceOf string } |
| 33 | |
| 34 | type plannedSelectionKey struct{} |
| 35 | |
| 36 | // WithPlannedSelection returns ctx carrying s. A selection with either part |
| 37 | // empty reads back as none, so a caller can mask one it inherited. |
| 38 | func WithPlannedSelection(ctx context.Context, s PlannedSelection) context.Context { |
| 39 | return context.WithValue(ctx, plannedSelectionKey{}, s) |
| 40 | } |
| 41 | |
| 42 | // PlannedSelectionFrom is the selection ctx carries, if a whole one. |
| 43 | func PlannedSelectionFrom(ctx context.Context) (PlannedSelection, bool) { |
| 44 | s, ok := ctx.Value(plannedSelectionKey{}).(PlannedSelection) |
| 45 | if !ok || s.Build == "" || s.InPlaceOf == "" { |
| 46 | return PlannedSelection{}, false |
| 47 | } |
| 48 | return s, true |
| 49 | } |
| 50 | |
| 51 | // recoverySelection is the selection a recovery plan makes (decideWake's |
| 52 | // recovery: the good build booted because the failure book blocks the |
| 53 | // installed build, or the installed build is not staged correctly): plan |
| 54 | // boots the route's good build, as no first wake, in place of the build root |
| 55 | // installed (rt.Version, the planner's "installed"). A plan that boots the |
| 56 | // installed build itself, the good build included, selects nothing in place |
| 57 | // of anything, and its record is revalidated as any other. |
| 58 | func recoverySelection(plan WakePlan, rt registry.Route) (PlannedSelection, bool) { |
| 59 | boot := plan.Boot.Version |
| 60 | if !plan.planned() || plan.FirstWake || boot == "" || boot != rt.GoodVersion || rt.Version == "" || rt.Version == boot { |
| 61 | return PlannedSelection{}, false |
| 62 | } |
| 63 | return PlannedSelection{Build: boot, InPlaceOf: rt.Version}, true |
| 64 | } |
| 65 | |
| 66 | // withRecoverySelection is ctx carrying plan's recovery selection when plan |
| 67 | // is a recovery and build is its boot; ctx itself otherwise. |
| 68 | func withRecoverySelection(ctx context.Context, plan WakePlan, rt registry.Route, build string) context.Context { |
| 69 | if s, ok := recoverySelection(plan, rt); ok && s.Build == build { |
| 70 | return WithPlannedSelection(ctx, s) |
| 71 | } |
| 72 | return ctx |
| 73 | } |
| 74 | |
amadan