| 1 | package registry |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "database/sql" |
| 7 | "encoding/json" |
| 8 | "errors" |
| 9 | "fmt" |
| 10 | "strings" |
| 11 | ) |
| 12 | |
| 13 | var ErrClaimOwnership = errors.New("registry: claim row ownership changed or unknown") |
| 14 | |
| 15 | type ClaimOwnership struct { |
| 16 | ClaimIncarnation string |
| 17 | ClaimStamp uint64 |
| 18 | ClaimOwner string |
| 19 | ClaimRowID string |
| 20 | } |
| 21 | |
| 22 | func (o ClaimOwnership) Valid() bool { |
| 23 | return o.ClaimIncarnation != "" && o.ClaimStamp != 0 && o.ClaimOwner != "" && o.ClaimRowID != "" |
| 24 | } |
| 25 | |
| 26 | type ClaimRow struct { |
| 27 | AllowAbsent bool `json:",omitempty"` |
| 28 | Kind string |
| 29 | Host string |
| 30 | Name string |
| 31 | Registration string |
| 32 | Ownership ClaimOwnership |
| 33 | } |
| 34 | type ClaimRowArchive struct { |
| 35 | Row ClaimRow |
| 36 | Contents json.RawMessage |
| 37 | } |
| 38 | |
| 39 | func (r *Registry) migrateClaimOwnership() error { |
| 40 | for _, table := range []string{"routes", "timers"} { |
| 41 | for _, column := range []string{"claim_incarnation TEXT NOT NULL DEFAULT ''", "claim_stamp INTEGER NOT NULL DEFAULT 0", "claim_owner TEXT NOT NULL DEFAULT ''", "claim_row_id TEXT NOT NULL DEFAULT ''"} { |
| 42 | if _, err := r.sql.Exec("ALTER TABLE " + table + " ADD COLUMN " + column); err != nil && !strings.Contains(err.Error(), "duplicate column") { |
| 43 | return err |
| 44 | } |
| 45 | } |
| 46 | } |
| 47 | _, err := r.sql.Exec(`CREATE TABLE IF NOT EXISTS claim_row_retirements ( |
| 48 | journal TEXT NOT NULL, kind TEXT NOT NULL, host TEXT NOT NULL, name TEXT NOT NULL, |
| 49 | row_id TEXT NOT NULL, archive BLOB NOT NULL, |
| 50 | PRIMARY KEY(journal,kind,host,name,row_id))`) |
| 51 | return err |
| 52 | } |
| 53 | |
| 54 | // AdoptClaimRoute is called only by the complete-census backfill coordinator. |
| 55 | // The full observed row is compared inside the write transaction. |
| 56 | func (r *Registry) AdoptClaimRoute(ctx context.Context, observed Route, owner ClaimOwnership) error { |
| 57 | if r.remote != nil { |
| 58 | _, err := r.remote.call(ctx, remoteRequest{Method: "AdoptClaimRoute", Observed: observed, Owner: owner}, nil) |
| 59 | return err |
| 60 | } |
| 61 | |
| 62 | if !owner.Valid() || observed.ClaimOwnership != (ClaimOwnership{}) { |
| 63 | return ErrClaimOwnership |
| 64 | } |
| 65 | tx, err := r.beginClaimTransaction(ctx, true) |
| 66 | if err != nil { |
| 67 | return err |
| 68 | } |
| 69 | defer tx.Rollback() |
| 70 | current, err := scanRoute(tx.QueryRowContext(ctx, `SELECT `+routeCols+` FROM routes WHERE host=?`, observed.Host).Scan) |
| 71 | if err != nil { |
| 72 | return err |
| 73 | } |
| 74 | a, _ := json.Marshal(current) |
| 75 | b, _ := json.Marshal(observed) |
| 76 | if !bytes.Equal(a, b) { |
| 77 | return ErrClaimOwnership |
| 78 | } |
| 79 | res, err := tx.ExecContext(ctx, `UPDATE routes SET claim_incarnation=?,claim_stamp=?,claim_owner=?,claim_row_id=? WHERE host=? AND claim_owner='' AND claim_stamp=0 AND claim_incarnation='' AND claim_row_id=''`, owner.ClaimIncarnation, owner.ClaimStamp, owner.ClaimOwner, owner.ClaimRowID, observed.Host) |
| 80 | if err != nil { |
| 81 | return err |
| 82 | } |
| 83 | n, err := res.RowsAffected() |
| 84 | if err != nil { |
| 85 | return err |
| 86 | } |
| 87 | if n != 1 { |
| 88 | return ErrClaimOwnership |
| 89 | } |
| 90 | return tx.Commit() |
| 91 | } |
| 92 | |
| 93 | // RetireClaimRows archives the exact transaction snapshot before deletion. |
| 94 | // A missing or replacement row is successful only when this journal's committed |
| 95 | // archive proves the predecessor was already removed by an earlier attempt. |
| 96 | func (r *Registry) RetireClaimRows(ctx context.Context, journal string, targets []ClaimRow, archive func([]ClaimRowArchive) error) error { |
| 97 | if archive == nil { |
| 98 | return ErrClaimOwnership |
| 99 | } |
| 100 | if r.remote != nil { |
| 101 | _, err := r.remote.call(ctx, remoteRequest{Method: "RetireClaimRows", Journal: journal, Targets: targets}, func(out remoteResponse) error { return archive(out.Archives) }) |
| 102 | return err |
| 103 | } |
| 104 | |
| 105 | if journal == "" || len(targets) == 0 || archive == nil { |
| 106 | return ErrClaimOwnership |
| 107 | } |
| 108 | tx, err := r.beginClaimTransaction(ctx, true) |
| 109 | if err != nil { |
| 110 | return err |
| 111 | } |
| 112 | defer tx.Rollback() |
| 113 | archives := make([]ClaimRowArchive, 0, len(targets)) |
| 114 | pending := make([]bool, len(targets)) |
| 115 | seen := map[string]bool{} |
| 116 | for i, t := range targets { |
| 117 | if t.AllowAbsent && t.Kind != "timer" { |
| 118 | return ErrClaimOwnership |
| 119 | } |
| 120 | if !t.Ownership.Valid() || t.Host == "" || (t.Kind != "route" && t.Kind != "timer") || (t.Kind == "timer" && (t.Name == "" || t.Registration == "")) || (t.Kind == "route" && (t.Name != "" || t.Registration != "")) { |
| 121 | return ErrClaimOwnership |
| 122 | } |
| 123 | key := t.Kind + "\x00" + t.Host + "\x00" + t.Name |
| 124 | if seen[key] { |
| 125 | return ErrClaimOwnership |
| 126 | } |
| 127 | seen[key] = true |
| 128 | var saved []byte |
| 129 | err = tx.QueryRowContext(ctx, `SELECT archive FROM claim_row_retirements WHERE journal=? AND kind=? AND host=? AND name=? AND row_id=?`, journal, t.Kind, t.Host, t.Name, t.Ownership.ClaimRowID).Scan(&saved) |
| 130 | if err == nil { |
| 131 | var a ClaimRowArchive |
| 132 | if json.Unmarshal(saved, &a) != nil || a.Row != t || len(a.Contents) == 0 { |
| 133 | return ErrClaimOwnership |
| 134 | } |
| 135 | archives = append(archives, a) |
| 136 | continue |
| 137 | } |
| 138 | if !errors.Is(err, sql.ErrNoRows) { |
| 139 | return err |
| 140 | } |
| 141 | var content []byte |
| 142 | switch t.Kind { |
| 143 | case "route": |
| 144 | row, e := scanRoute(tx.QueryRowContext(ctx, `SELECT `+routeCols+` FROM routes WHERE host=?`, t.Host).Scan) |
| 145 | if e != nil { |
| 146 | return fmt.Errorf("%w: %v", ErrClaimOwnership, e) |
| 147 | } |
| 148 | if row.ClaimOwnership != t.Ownership { |
| 149 | return ErrClaimOwnership |
| 150 | } |
| 151 | content, err = json.Marshal(row) |
| 152 | case "timer": |
| 153 | row, e := scanTimer(tx.QueryRowContext(ctx, `SELECT `+timerCols+` FROM timers WHERE host=? AND name=?`, t.Host, t.Name)) |
| 154 | if errors.Is(e, sql.ErrNoRows) && t.AllowAbsent { |
| 155 | content, err = []byte("null"), nil |
| 156 | break |
| 157 | } |
| 158 | if e != nil { |
| 159 | return fmt.Errorf("%w: %v", ErrClaimOwnership, e) |
| 160 | } |
| 161 | if row.ClaimOwnership != t.Ownership || row.Registration != t.Registration { |
| 162 | return ErrClaimOwnership |
| 163 | } |
| 164 | content, err = json.Marshal(struct { |
| 165 | Timer Timer |
| 166 | Registration string |
| 167 | }{row, row.Registration}) |
| 168 | } |
| 169 | if err != nil { |
| 170 | return err |
| 171 | } |
| 172 | archives = append(archives, ClaimRowArchive{Row: t, Contents: content}) |
| 173 | pending[i] = true |
| 174 | } |
| 175 | if err = archive(archives); err != nil { |
| 176 | return err |
| 177 | } |
| 178 | for i, t := range targets { |
| 179 | if !pending[i] { |
| 180 | continue |
| 181 | } |
| 182 | a, err := json.Marshal(archives[i]) |
| 183 | if err != nil { |
| 184 | return err |
| 185 | } |
| 186 | if _, err = tx.ExecContext(ctx, `INSERT INTO claim_row_retirements (journal,kind,host,name,row_id,archive) VALUES (?,?,?,?,?,?)`, journal, t.Kind, t.Host, t.Name, t.Ownership.ClaimRowID, a); err != nil { |
| 187 | return err |
| 188 | } |
| 189 | table := "routes" |
| 190 | q := "" |
| 191 | args := []any{t.Host, t.Ownership.ClaimIncarnation, t.Ownership.ClaimStamp, t.Ownership.ClaimOwner, t.Ownership.ClaimRowID} |
| 192 | if t.Kind == "timer" { |
| 193 | table = "timers" |
| 194 | q = " AND name=? AND registration=?" |
| 195 | args = append(args, t.Name, t.Registration) |
| 196 | } |
| 197 | res, e := tx.ExecContext(ctx, `DELETE FROM `+table+` WHERE host=? AND claim_incarnation=? AND claim_stamp=? AND claim_owner=? AND claim_row_id=?`+q, args...) |
| 198 | if e != nil { |
| 199 | return e |
| 200 | } |
| 201 | n, e := res.RowsAffected() |
| 202 | if e != nil { |
| 203 | return e |
| 204 | } |
| 205 | if n != 1 && !(n == 0 && t.AllowAbsent && string(archives[i].Contents) == "null") { |
| 206 | return ErrClaimOwnership |
| 207 | } |
| 208 | } |
| 209 | return tx.Commit() |
| 210 | } |
| 211 | |
| 212 | func (r *Registry) AdoptClaimTimer(ctx context.Context, observed Timer, owner ClaimOwnership) error { |
| 213 | if r.remote != nil { |
| 214 | _, err := r.remote.call(ctx, remoteRequest{Method: "AdoptClaimTimer", ObservedValue: observed, Owner: owner}, nil) |
| 215 | return err |
| 216 | } |
| 217 | |
| 218 | if !owner.Valid() || observed.ClaimOwnership != (ClaimOwnership{}) || observed.Registration == "" || owner.ClaimRowID != observed.Registration { |
| 219 | return ErrClaimOwnership |
| 220 | } |
| 221 | tx, err := r.beginClaimTransaction(ctx, true) |
| 222 | if err != nil { |
| 223 | return err |
| 224 | } |
| 225 | defer tx.Rollback() |
| 226 | current, err := scanTimer(tx.QueryRowContext(ctx, `SELECT `+timerCols+` FROM timers WHERE host=? AND name=?`, observed.Host, observed.Name)) |
| 227 | if err != nil { |
| 228 | return err |
| 229 | } |
| 230 | if current != observed { |
| 231 | return ErrClaimOwnership |
| 232 | } |
| 233 | res, err := tx.ExecContext(ctx, `UPDATE timers SET claim_incarnation=?,claim_stamp=?,claim_owner=?,claim_row_id=? WHERE host=? AND name=? AND registration=? AND claim_owner='' AND claim_stamp=0 AND claim_incarnation='' AND claim_row_id=''`, owner.ClaimIncarnation, owner.ClaimStamp, owner.ClaimOwner, owner.ClaimRowID, observed.Host, observed.Name, observed.Registration) |
| 234 | if err != nil { |
| 235 | return err |
| 236 | } |
| 237 | n, err := res.RowsAffected() |
| 238 | if err != nil { |
| 239 | return err |
| 240 | } |
| 241 | if n != 1 { |
| 242 | return ErrClaimOwnership |
| 243 | } |
| 244 | return tx.Commit() |
| 245 | } |
| 246 | |
amadan