| 1 | package lease |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "io" |
| 8 | "log/slog" |
| 9 | "path" |
| 10 | "strings" |
| 11 | "time" |
| 12 | |
| 13 | "github.com/benbjohnson/litestream" |
| 14 | "github.com/superfly/ltx" |
| 15 | ) |
| 16 | |
| 17 | var ErrGenerationRetention = errors.New("lease: generation retention requires exact versions through park") |
| 18 | |
| 19 | var ErrGenerationBinding = errors.New("lease: invalid or changed generation binding") |
| 20 | |
| 21 | const generationRequestLimit = 120 * time.Second |
| 22 | |
| 23 | // BindGeneration fixes all replica data requests below the held lease's |
| 24 | // location. The authority callback is captured once and checked per request. |
| 25 | func (h *Held) BindGeneration(prefix string, check func(context.Context) error) error { |
| 26 | if h == nil || h.leaser == nil || check == nil { |
| 27 | return ErrGenerationBinding |
| 28 | } |
| 29 | base := strings.TrimSuffix(path.Clean(h.leaser.Path), "/") |
| 30 | clean := path.Clean(prefix) |
| 31 | rel, ok := strings.CutPrefix(clean, base+"/") |
| 32 | if (prefix != clean && prefix != clean+"/") || strings.Contains(prefix, "\\") || base == "." || base == "" || !ok || strings.Contains(rel, "/") || !strings.HasPrefix(rel, "g-") || len(rel) == 2 { |
| 33 | return ErrGenerationBinding |
| 34 | } |
| 35 | h.mu.Lock() |
| 36 | defer h.mu.Unlock() |
| 37 | if h.busy || h.spent || h.generationPrefix != "" { |
| 38 | return ErrGenerationBinding |
| 39 | } |
| 40 | client := h.replicaClient |
| 41 | if client == nil { |
| 42 | var err error |
| 43 | client, err = newReplicaClient(h.leaser.Bucket, clean, h.region) |
| 44 | if err != nil { |
| 45 | return err |
| 46 | } |
| 47 | } |
| 48 | h.replicaClient = &generationClient{client: client, check: check} |
| 49 | h.generationPrefix = clean |
| 50 | return nil |
| 51 | } |
| 52 | |
| 53 | // BindRoot is BindGeneration for the root layout (hostclaim.RootGeneration): |
| 54 | // the replica data sits directly below the held lease's location, so no |
| 55 | // prefix changes, but every replica request still first passes check, the |
| 56 | // authority read before each one (moves §5.3 step 5, ruling G3; Task 5 fix |
| 57 | // round 1, ruling 2). Without it a root-generation checkpoint would check |
| 58 | // its authority once and then run every request unchecked. As immutable as |
| 59 | // BindGeneration, and exclusive with it. Retention stays off under it, as |
| 60 | // under a bound generation: the checking client refuses DeleteLTXFiles. |
| 61 | func (h *Held) BindRoot(check func(context.Context) error) error { |
| 62 | if h == nil || h.leaser == nil || check == nil { |
| 63 | return ErrGenerationBinding |
| 64 | } |
| 65 | base := strings.TrimSuffix(path.Clean(h.leaser.Path), "/") |
| 66 | if base == "." || base == "" { |
| 67 | return ErrGenerationBinding |
| 68 | } |
| 69 | h.mu.Lock() |
| 70 | defer h.mu.Unlock() |
| 71 | if h.busy || h.spent || h.generationPrefix != "" { |
| 72 | return ErrGenerationBinding |
| 73 | } |
| 74 | client := h.replicaClient |
| 75 | if client == nil { |
| 76 | var err error |
| 77 | client, err = newReplicaClient(h.leaser.Bucket, base, h.region) |
| 78 | if err != nil { |
| 79 | return err |
| 80 | } |
| 81 | } |
| 82 | h.replicaClient = &generationClient{client: client, check: check} |
| 83 | // The lease's own path marks the binding, so neither BindGeneration nor |
| 84 | // a second BindRoot can change the client under a running checkpoint, |
| 85 | // and newStore keeps retention off. |
| 86 | h.generationPrefix = base |
| 87 | return nil |
| 88 | } |
| 89 | |
| 90 | type generationClient struct { |
| 91 | client litestream.ReplicaClient |
| 92 | check func(context.Context) error |
| 93 | } |
| 94 | |
| 95 | func (c *generationClient) Type() string { return c.client.Type() } |
| 96 | func (c *generationClient) SetLogger(l *slog.Logger) { c.client.SetLogger(l) } |
| 97 | func generationLevel(level int) error { |
| 98 | if level < 0 || level > litestream.SnapshotLevel { |
| 99 | return ErrGenerationBinding |
| 100 | } |
| 101 | return nil |
| 102 | } |
| 103 | func generationCoords(level int, min, max ltx.TXID) error { |
| 104 | if generationLevel(level) != nil || min == 0 || max == 0 || min > max { |
| 105 | return ErrGenerationBinding |
| 106 | } |
| 107 | return nil |
| 108 | } |
| 109 | func (c *generationClient) bounded(ctx context.Context) (context.Context, context.CancelFunc, error) { |
| 110 | if ctx == nil { |
| 111 | return nil, nil, ErrGenerationBinding |
| 112 | } |
| 113 | ctx, cancel := context.WithTimeout(ctx, generationRequestLimit) |
| 114 | if err := c.check(ctx); err != nil { |
| 115 | cancel() |
| 116 | return nil, nil, err |
| 117 | } |
| 118 | return ctx, cancel, nil |
| 119 | } |
| 120 | func (c *generationClient) Init(ctx context.Context) error { |
| 121 | ctx, cancel, err := c.bounded(ctx) |
| 122 | if err != nil { |
| 123 | return err |
| 124 | } |
| 125 | defer cancel() |
| 126 | return c.client.Init(ctx) |
| 127 | } |
| 128 | func (c *generationClient) LTXFiles(ctx context.Context, level int, seek ltx.TXID, metadata bool) (ltx.FileIterator, error) { |
| 129 | if err := generationLevel(level); err != nil { |
| 130 | return nil, err |
| 131 | } |
| 132 | ctx, cancel, err := c.bounded(ctx) |
| 133 | if err != nil { |
| 134 | return nil, err |
| 135 | } |
| 136 | it, err := c.client.LTXFiles(ctx, level, seek, metadata) |
| 137 | if err != nil { |
| 138 | cancel() |
| 139 | return nil, err |
| 140 | } |
| 141 | return &generationIterator{FileIterator: it, cancel: cancel}, nil |
| 142 | } |
| 143 | func (c *generationClient) OpenLTXFile(ctx context.Context, level int, min, max ltx.TXID, offset, size int64) (io.ReadCloser, error) { |
| 144 | if err := generationCoords(level, min, max); err != nil || offset < 0 || size < 0 { |
| 145 | return nil, ErrGenerationBinding |
| 146 | } |
| 147 | ctx, cancel, err := c.bounded(ctx) |
| 148 | if err != nil { |
| 149 | return nil, err |
| 150 | } |
| 151 | rc, err := c.client.OpenLTXFile(ctx, level, min, max, offset, size) |
| 152 | if err != nil { |
| 153 | cancel() |
| 154 | return nil, err |
| 155 | } |
| 156 | return &generationReader{ReadCloser: rc, cancel: cancel}, nil |
| 157 | } |
| 158 | func (c *generationClient) WriteLTXFile(ctx context.Context, level int, min, max ltx.TXID, r io.Reader) (*ltx.FileInfo, error) { |
| 159 | if pipe, ok := r.(*io.PipeReader); ok { |
| 160 | defer pipe.Close() |
| 161 | } |
| 162 | if err := generationCoords(level, min, max); err != nil || r == nil { |
| 163 | return nil, ErrGenerationBinding |
| 164 | } |
| 165 | ctx, cancel, err := c.bounded(ctx) |
| 166 | if err != nil { |
| 167 | return nil, err |
| 168 | } |
| 169 | defer cancel() |
| 170 | return c.client.WriteLTXFile(ctx, level, min, max, r) |
| 171 | } |
| 172 | func (c *generationClient) DeleteLTXFiles(ctx context.Context, files []*ltx.FileInfo) error { |
| 173 | if len(files) == 0 { |
| 174 | return ErrGenerationBinding |
| 175 | } |
| 176 | for _, f := range files { |
| 177 | if f == nil || generationCoords(f.Level, f.MinTXID, f.MaxTXID) != nil { |
| 178 | return ErrGenerationBinding |
| 179 | } |
| 180 | } |
| 181 | // FileInfo has no VersionID. Only the park engine may retire exact versions. |
| 182 | return ErrGenerationRetention |
| 183 | } |
| 184 | func (c *generationClient) DeleteAll(context.Context) error { |
| 185 | return fmt.Errorf("%w: DeleteAll refused", ErrGenerationBinding) |
| 186 | } |
| 187 | |
| 188 | type generationReader struct { |
| 189 | io.ReadCloser |
| 190 | cancel context.CancelFunc |
| 191 | } |
| 192 | |
| 193 | func (r *generationReader) Close() error { err := r.ReadCloser.Close(); r.cancel(); return err } |
| 194 | |
| 195 | type generationIterator struct { |
| 196 | ltx.FileIterator |
| 197 | cancel context.CancelFunc |
| 198 | } |
| 199 | |
| 200 | func (i *generationIterator) Close() error { err := i.FileIterator.Close(); i.cancel(); return err } |
| 201 | |
amadan