| 1 | package moves |
| 2 | |
| 3 | import ( |
| 4 | "go/ast" |
| 5 | "go/parser" |
| 6 | "go/token" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | "reflect" |
| 10 | "strings" |
| 11 | "testing" |
| 12 | "time" |
| 13 | ) |
| 14 | |
| 15 | const ( |
| 16 | tjHost = "a.go.example.com" |
| 17 | tjOp = "mv_abcdefghijklmnopqrstuvwxyz" |
| 18 | ) |
| 19 | |
| 20 | func tjRead(t *testing.T, dd string) *Journal { |
| 21 | t.Helper() |
| 22 | j, err := ReadJournal(dd, tjHost, tjOp) |
| 23 | if err != nil { |
| 24 | t.Fatal(err) |
| 25 | } |
| 26 | return j |
| 27 | } |
| 28 | |
| 29 | func tjCommit(t *testing.T, dd string, j *Journal) { |
| 30 | t.Helper() |
| 31 | if err := j.Commit(dd); err != nil { |
| 32 | t.Fatal(err) |
| 33 | } |
| 34 | } |
| 35 | |
| 36 | // Fix round 1, ruling 3, and fix round 2, ruling 2: a move's journal has |
| 37 | // more than one writer on a box (the landing's pass, the probe owners and |
| 38 | // attempts), each a read-modify-write through UpdateJournal: a writer that |
| 39 | // read before another's write commits only its own changes, so the |
| 40 | // landing's progress mark and the other writer's step both survive, in |
| 41 | // either order. A step the writer itself removes is removed. |
| 42 | func TestJournalWritersKeepEachOthersSteps(t *testing.T) { |
| 43 | dd := t.TempDir() |
| 44 | landing, other := tjRead(t, dd), tjRead(t, dd) |
| 45 | other.Mark("files-plain-g1", "sha256:f") |
| 46 | tjCommit(t, dd, other) |
| 47 | landing.Phase, landing.Attempt = "probing", 1 |
| 48 | landing.Mark("probe-admitting-1", `{"session":7}`) |
| 49 | tjCommit(t, dd, landing) |
| 50 | got := tjRead(t, dd) |
| 51 | if !got.Done("files-plain-g1") || !got.Done("probe-admitting-1") || got.Phase != "probing" || got.Attempt != 1 { |
| 52 | t.Fatalf("after the landing's later commit: %+v", got) |
| 53 | } |
| 54 | if !landing.Done("files-plain-g1") { |
| 55 | t.Fatalf("a committed value is not the journal as written: %+v", landing.Steps) |
| 56 | } |
| 57 | |
| 58 | // The other order: the other writer commits last. |
| 59 | landing, other = tjRead(t, dd), tjRead(t, dd) |
| 60 | landing.Mark("probe-passed-1", "ok") |
| 61 | tjCommit(t, dd, landing) |
| 62 | other.Mark("files-plain-g2", "sha256:g") |
| 63 | tjCommit(t, dd, other) |
| 64 | got = tjRead(t, dd) |
| 65 | if !got.Done("probe-passed-1") || !got.Done("files-plain-g2") || !got.Done("probe-admitting-1") || !got.Done("files-plain-g1") || got.Phase != "probing" { |
| 66 | t.Fatalf("after the other's later commit: %+v", got) |
| 67 | } |
| 68 | |
| 69 | // A step the writer removes is removed; another's is not touched. |
| 70 | j := tjRead(t, dd) |
| 71 | j.Unmark("probe-passed-1") |
| 72 | tjCommit(t, dd, j) |
| 73 | if got := tjRead(t, dd); got.Done("probe-passed-1") || !got.Done("files-plain-g2") { |
| 74 | t.Fatalf("after an Unmark: %+v", got.Steps) |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | // Fix round 2, ruling 2: a stale writer never restores a value another |
| 79 | // writer advanced or deleted after the stale writer read it. It writes only |
| 80 | // what it changed itself. |
| 81 | func TestStaleJournalWriterRestoresNothing(t *testing.T) { |
| 82 | dd := t.TempDir() |
| 83 | if err := UpdateJournal(dd, tjHost, tjOp, func(j *Journal) error { |
| 84 | j.Mark("probe-attempt-1", "started") |
| 85 | j.Mark("scratch", "here") |
| 86 | j.Phase = "restored" |
| 87 | return nil |
| 88 | }); err != nil { |
| 89 | t.Fatal(err) |
| 90 | } |
| 91 | stale := tjRead(t, dd) |
| 92 | // Another writer advances one step, deletes another and moves the phase. |
| 93 | if err := UpdateJournal(dd, tjHost, tjOp, func(j *Journal) error { |
| 94 | j.Mark("probe-attempt-1", "passed") |
| 95 | j.Unmark("scratch") |
| 96 | j.Phase = "probing" |
| 97 | return nil |
| 98 | }); err != nil { |
| 99 | t.Fatal(err) |
| 100 | } |
| 101 | stale.Mark("probe-admitting-2", "x") |
| 102 | tjCommit(t, dd, stale) |
| 103 | got := tjRead(t, dd) |
| 104 | if got.Steps["probe-attempt-1"] != "passed" { |
| 105 | t.Errorf("an advanced step was restored: %q", got.Steps["probe-attempt-1"]) |
| 106 | } |
| 107 | if got.Done("scratch") { |
| 108 | t.Errorf("a deleted step was restored: %+v", got.Steps) |
| 109 | } |
| 110 | if got.Phase != "probing" { |
| 111 | t.Errorf("a phase the stale writer did not change was restored: %q", got.Phase) |
| 112 | } |
| 113 | if !got.Done("probe-admitting-2") { |
| 114 | t.Errorf("the stale writer's own change is lost: %+v", got) |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | // Fix round 1, ruling 3: one lock per journal. A writer that commits while |
| 119 | // another holds the journal in UpdateJournal (the landing's admitting mark) |
| 120 | // waits for it, and both changes are in the journal after. |
| 121 | func TestJournalLockSerializesWriters(t *testing.T) { |
| 122 | dd := t.TempDir() |
| 123 | other := tjRead(t, dd) |
| 124 | other.Mark("files-plain-g1", "sha256:f") |
| 125 | done := make(chan error, 1) |
| 126 | err := UpdateJournal(dd, tjHost, tjOp, func(j *Journal) error { |
| 127 | go func() { done <- other.Commit(dd) }() |
| 128 | select { |
| 129 | case err := <-done: |
| 130 | t.Errorf("a commit wrote the journal (%v) while UpdateJournal held it", err) |
| 131 | case <-time.After(100 * time.Millisecond): |
| 132 | } |
| 133 | j.Phase, j.Attempt = "probing", 1 |
| 134 | j.Mark("probe-admitting-1", `{"session":7}`) |
| 135 | return nil |
| 136 | }) |
| 137 | if err != nil { |
| 138 | t.Fatal(err) |
| 139 | } |
| 140 | if err := <-done; err != nil { |
| 141 | t.Fatal(err) |
| 142 | } |
| 143 | got := tjRead(t, dd) |
| 144 | if !got.Done("probe-admitting-1") || !got.Done("files-plain-g1") || got.Phase != "probing" { |
| 145 | t.Fatalf("the journal lost a writer's change: %+v", got) |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | // Fix round 2, ruling 2: there is no plain write. Journal has no exported |
| 150 | // Write, and the whole-file write (write) is called only by UpdateJournal, |
| 151 | // which holds the lock across the read, the change and the write; every |
| 152 | // other writer commits its own changes through it (Commit). A production |
| 153 | // caller cannot read a journal and then write it whole. |
| 154 | func TestJournalHasNoPlainWrite(t *testing.T) { |
| 155 | if _, ok := reflect.TypeOf(&Journal{}).MethodByName("Write"); ok { |
| 156 | t.Fatal("Journal has a plain Write") |
| 157 | } |
| 158 | files, err := filepath.Glob("*.go") |
| 159 | if err != nil { |
| 160 | t.Fatal(err) |
| 161 | } |
| 162 | fset := token.NewFileSet() |
| 163 | var callers []string |
| 164 | for _, f := range files { |
| 165 | if strings.HasSuffix(f, "_test.go") { |
| 166 | continue |
| 167 | } |
| 168 | af, err := parser.ParseFile(fset, f, nil, 0) |
| 169 | if err != nil { |
| 170 | t.Fatal(err) |
| 171 | } |
| 172 | for _, d := range af.Decls { |
| 173 | fd, ok := d.(*ast.FuncDecl) |
| 174 | if !ok || fd.Body == nil { |
| 175 | continue |
| 176 | } |
| 177 | ast.Inspect(fd.Body, func(n ast.Node) bool { |
| 178 | if c, ok := n.(*ast.CallExpr); ok { |
| 179 | if sel, ok := c.Fun.(*ast.SelectorExpr); ok && sel.Sel.Name == "write" { |
| 180 | callers = append(callers, f+":"+fd.Name.Name) |
| 181 | } |
| 182 | } |
| 183 | return true |
| 184 | }) |
| 185 | } |
| 186 | } |
| 187 | if !reflect.DeepEqual(callers, []string{"journal.go:UpdateJournal"}) { |
| 188 | t.Fatalf("the journal's whole-file write is called by %v, want only UpdateJournal", callers) |
| 189 | } |
| 190 | // Every journal written in this package's tests reads back: a smoke |
| 191 | // check that Commit makes a journal where there was none. |
| 192 | dd := t.TempDir() |
| 193 | j := tjRead(t, dd) |
| 194 | j.Mark("a", "b") |
| 195 | tjCommit(t, dd, j) |
| 196 | if _, err := os.Stat(filepath.Join(JournalDir(dd, tjHost, tjOp), journalFile)); err != nil { |
| 197 | t.Fatalf("Commit made no journal: %v", err) |
| 198 | } |
| 199 | } |
| 200 | |
amadan