| 1 | package registry |
| 2 | |
| 3 | import ( |
| 4 | "path/filepath" |
| 5 | "sync" |
| 6 | "testing" |
| 7 | "time" |
| 8 | ) |
| 9 | |
| 10 | // A generation is never handed out twice by one registry file, across a |
| 11 | // close and reopen (an agent restart) and whatever the clock says: a |
| 12 | // rollback resumed after a restart compares and lifts by the generation it |
| 13 | // stored before it, so a later fence must never carry the same number. |
| 14 | func TestNextFenceGenerationIsUniqueAcrossRestarts(t *testing.T) { |
| 15 | path := filepath.Join(t.TempDir(), "registry.db") |
| 16 | reg, err := Open(path) |
| 17 | if err != nil { |
| 18 | t.Fatal(err) |
| 19 | } |
| 20 | now := time.Unix(1_800_000_000, 0) |
| 21 | before := map[uint64]bool{} |
| 22 | var last uint64 |
| 23 | for i := 0; i < 5; i++ { |
| 24 | g, err := reg.NextFenceGeneration(now) // the same instant: still distinct |
| 25 | if err != nil { |
| 26 | t.Fatal(err) |
| 27 | } |
| 28 | if g == 0 || g <= last { |
| 29 | t.Fatalf("generation %d after %d: want nonzero and rising", g, last) |
| 30 | } |
| 31 | before[g], last = true, g |
| 32 | } |
| 33 | if err := reg.Close(); err != nil { |
| 34 | t.Fatal(err) |
| 35 | } |
| 36 | |
| 37 | reg, err = Open(path) |
| 38 | if err != nil { |
| 39 | t.Fatal(err) |
| 40 | } |
| 41 | defer reg.Close() |
| 42 | // The clock went back across the restart (a box that booted before NTP |
| 43 | // synced): the generations still rise past every one handed out before. |
| 44 | for _, at := range []time.Time{now.Add(-time.Hour), now, time.Unix(0, 0), now.Add(-time.Nanosecond)} { |
| 45 | g, err := reg.NextFenceGeneration(at) |
| 46 | if err != nil { |
| 47 | t.Fatal(err) |
| 48 | } |
| 49 | if before[g] || g <= last { |
| 50 | t.Fatalf("after the restart, at %v: generation %d (last before %d)", at, g, last) |
| 51 | } |
| 52 | last = g |
| 53 | } |
| 54 | // A clock ahead of every earlier generation is followed: generations |
| 55 | // stay in wall-clock nanoseconds, the space the layout pass and the |
| 56 | // moves cut draw theirs from. |
| 57 | later := now.Add(time.Hour) |
| 58 | if g, err := reg.NextFenceGeneration(later); err != nil || g != uint64(later.UnixNano()) { |
| 59 | t.Fatalf("a clock ahead: generation %d, %v; want %d", g, err, later.UnixNano()) |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | func TestNextFenceGenerationConcurrentCallersNeverShare(t *testing.T) { |
| 64 | reg := openTestRegistry(t) |
| 65 | now := time.Unix(1_800_000_000, 0) |
| 66 | const n = 40 |
| 67 | gens := make(chan uint64, n) |
| 68 | var wg sync.WaitGroup |
| 69 | for i := 0; i < n; i++ { |
| 70 | wg.Add(1) |
| 71 | go func() { |
| 72 | defer wg.Done() |
| 73 | g, err := reg.NextFenceGeneration(now) |
| 74 | if err != nil { |
| 75 | t.Error(err) |
| 76 | return |
| 77 | } |
| 78 | gens <- g |
| 79 | }() |
| 80 | } |
| 81 | wg.Wait() |
| 82 | close(gens) |
| 83 | seen := map[uint64]bool{} |
| 84 | for g := range gens { |
| 85 | if seen[g] { |
| 86 | t.Fatalf("generation %d handed out twice", g) |
| 87 | } |
| 88 | seen[g] = true |
| 89 | } |
| 90 | } |
| 91 | |
amadan