| 1 | // Ported from plan 3 task 2 (isolated-exec design §8.1): the classification |
| 2 | // that decides whether a route's paths are today's flat layout, the nested |
| 3 | // per-instance layout, or something an operator needs to look at. |
| 4 | package activator |
| 5 | |
| 6 | import ( |
| 7 | "fmt" |
| 8 | "log" |
| 9 | "path/filepath" |
| 10 | |
| 11 | "github.com/carlosframework/platform/internal/provision" |
| 12 | "github.com/carlosframework/platform/internal/registry" |
| 13 | ) |
| 14 | |
| 15 | // Layout is the classification of an activator-managed route's paths |
| 16 | // (isolated-exec design §8.1). It decides the spawn path: flat and foreign |
| 17 | // rows run today's exec child; nested rows run as units; fenced and |
| 18 | // conflict rows refuse to wake. |
| 19 | type Layout string |
| 20 | |
| 21 | const ( |
| 22 | LayoutFlat Layout = "flat" |
| 23 | LayoutNested Layout = "nested" |
| 24 | LayoutFenced Layout = "fenced" |
| 25 | LayoutConflict Layout = "conflict" |
| 26 | LayoutForeign Layout = "foreign" |
| 27 | ) |
| 28 | |
| 29 | // LayoutInputs are the box facts Classify needs beyond the row: where the |
| 30 | // data dir is, whether a migration journal exists for a host (plan 4 |
| 31 | // writes them), and the other rows on the box (for identifier conflicts). |
| 32 | // Nil seams mean "never fenced" and "never conflict", which is what unit |
| 33 | // tests without a box want. |
| 34 | type LayoutInputs struct { |
| 35 | DataDir string |
| 36 | // SocketDir is where flat sockets live and under which the nested |
| 37 | // instances directory sits. Empty means provision.SocketDir; a test |
| 38 | // points it at a temp dir so a route can classify as nested without |
| 39 | // writing to /run/carlos. |
| 40 | SocketDir string |
| 41 | Journal func(host string) bool |
| 42 | Peers func() ([]registry.Route, error) |
| 43 | // SameID reports whether two hosts share an instance identifier. Nil |
| 44 | // means provision.InstanceID equality; tests inject a collision. |
| 45 | SameID func(a, b string) bool |
| 46 | } |
| 47 | |
| 48 | // sockets returns the flat and nested socket paths for host under the |
| 49 | // configured socket directory. |
| 50 | func (in LayoutInputs) sockets(host string) (flat, nested string) { |
| 51 | dir := in.SocketDir |
| 52 | if dir == "" { |
| 53 | dir = provision.SocketDir |
| 54 | } |
| 55 | return filepath.Join(dir, host+".sock"), filepath.Join(dir, "instances", provision.InstanceID(host), "app.sock") |
| 56 | } |
| 57 | |
| 58 | // ActivatorManaged is the activator's own predicate for a route it owns |
| 59 | // (activator.go's per-host gate and edge.go's proxy decision): an instance |
| 60 | // route, hibernate-flagged, with a socket, not unit-backed, not |
| 61 | // tunnel-served. An unflagged socket route is an externally supervised |
| 62 | // process and is nobody's to migrate or isolate (design §8.2 step 1). |
| 63 | func ActivatorManaged(rt registry.Route) bool { |
| 64 | return rt.Kind == "instance" && rt.Hibernate && rt.Socket != "" && rt.Backing == "" && rt.Tunnel == "" |
| 65 | } |
| 66 | |
| 67 | // Classifier lets doWake ask a backend for a route's layout before it does |
| 68 | // anything the layout might forbid: acquiring the lease or restoring a |
| 69 | // database. A backend that does not implement it (a test double, say) is |
| 70 | // simply not asked, and the in-Start/in-Seed refusal still catches a fenced |
| 71 | // or conflicting row after the fact. |
| 72 | type Classifier interface { |
| 73 | Layout(rt registry.Route) (Layout, string) |
| 74 | } |
| 75 | |
| 76 | // Classify returns the layout and, for anything but flat and nested, the |
| 77 | // reason a member or operator sees. |
| 78 | func Classify(rt registry.Route, in LayoutInputs) (Layout, string) { |
| 79 | if in.Journal != nil && in.Journal(rt.Host) { |
| 80 | return LayoutFenced, "layout migration in flight; see " + provision.LayoutJournalPath(in.DataDir, rt.Host) |
| 81 | } |
| 82 | if in.Peers != nil { |
| 83 | same := in.SameID |
| 84 | if same == nil { |
| 85 | same = func(a, b string) bool { return provision.InstanceID(a) == provision.InstanceID(b) } |
| 86 | } |
| 87 | peers, err := in.Peers() |
| 88 | if err != nil { |
| 89 | // Fail open, not the fenced/conflict refusal itself: a registry |
| 90 | // read that fails here would otherwise silently skip the |
| 91 | // conflict check with no trace that it never ran. Loud, so a |
| 92 | // registry problem during a wake shows up in carlos logs rather |
| 93 | // than only in a collision nobody could explain later. |
| 94 | log.Printf("activator: %s: peer list for conflict check: %v (proceeding)", rt.Host, err) |
| 95 | } else { |
| 96 | for _, p := range peers { |
| 97 | if p.Host != rt.Host && ActivatorManaged(p) && same(p.Host, rt.Host) { |
| 98 | return LayoutConflict, fmt.Sprintf("instance identifier collides with %s; neither host wakes until one is removed", p.Host) |
| 99 | } |
| 100 | } |
| 101 | } |
| 102 | } |
| 103 | flatSock, nestedSock := in.sockets(rt.Host) |
| 104 | switch { |
| 105 | case rt.DBPath == provision.DefaultDBPath(in.DataDir, rt.Host) && rt.Socket == flatSock: |
| 106 | return LayoutFlat, "" |
| 107 | case rt.DBPath == provision.NestedDBPath(in.DataDir, rt.Host) && rt.Socket == nestedSock: |
| 108 | return LayoutNested, "" |
| 109 | } |
| 110 | return LayoutForeign, fmt.Sprintf("db %q socket %q are neither the flat nor the nested defaults", rt.DBPath, rt.Socket) |
| 111 | } |
| 112 | |
amadan