| 1 | package provision |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "encoding/json" |
| 7 | "errors" |
| 8 | "io" |
| 9 | "strconv" |
| 10 | "strings" |
| 11 | |
| 12 | "github.com/carlosframework/platform/internal/release" |
| 13 | ) |
| 14 | |
| 15 | // IsRecordKey recognizes both instance and sidecar control records. |
| 16 | func IsRecordKey(key string) bool { |
| 17 | p := strings.Split(key, "/") |
| 18 | return len(p) == 5 && p[0] == "apps" && (p[3] == "instances" || p[3] == "sidecars") && strings.HasSuffix(p[4], ".json") |
| 19 | } |
| 20 | |
| 21 | var ErrRecordSequence = errors.New("provision: invalid record sequence") |
| 22 | var ErrRecordSequenceExhausted = errors.New("provision: record sequence exhausted") |
| 23 | |
| 24 | type recordSequenceKey struct{} |
| 25 | type preparedRecordKey struct{} |
| 26 | |
| 27 | // WithRecordSequence introduces the counter on a first claim-mode write. |
| 28 | // A populated counter advances even without this context. This is encoding, |
| 29 | // not mutation authority; callers retain their existing claim and app gates. |
| 30 | func WithRecordSequence(ctx context.Context) context.Context { |
| 31 | return context.WithValue(ctx, recordSequenceKey{}, true) |
| 32 | } |
| 33 | |
| 34 | // RecordSequence preserves unknown fields and parses the counter without a |
| 35 | // float64 round trip. Missing means legacy zero; null, aliases, duplicates, |
| 36 | // fractions, negatives and overflow refuse at the claim-on write boundary. |
| 37 | func RecordSequence(body []byte) (map[string]json.RawMessage, uint64, error) { |
| 38 | d := json.NewDecoder(bytes.NewReader(body)) |
| 39 | if first, err := d.Token(); err != nil || first != json.Delim('{') { |
| 40 | return nil, 0, ErrRecordSequence |
| 41 | } |
| 42 | fields := map[string]json.RawMessage{} |
| 43 | var seq uint64 |
| 44 | for d.More() { |
| 45 | token, err := d.Token() |
| 46 | if err != nil { |
| 47 | return nil, 0, ErrRecordSequence |
| 48 | } |
| 49 | name, ok := token.(string) |
| 50 | if !ok { |
| 51 | return nil, 0, ErrRecordSequence |
| 52 | } |
| 53 | if _, exists := fields[name]; exists { |
| 54 | return nil, 0, ErrRecordSequence |
| 55 | } |
| 56 | var value json.RawMessage |
| 57 | if d.Decode(&value) != nil { |
| 58 | return nil, 0, ErrRecordSequence |
| 59 | } |
| 60 | if strings.EqualFold(name, "record_seq") { |
| 61 | if name != "record_seq" { |
| 62 | return nil, 0, ErrRecordSequence |
| 63 | } |
| 64 | seq, err = strconv.ParseUint(string(value), 10, 64) |
| 65 | if err != nil { |
| 66 | return nil, 0, ErrRecordSequence |
| 67 | } |
| 68 | } |
| 69 | fields[name] = value |
| 70 | } |
| 71 | if end, err := d.Token(); err != nil || end != json.Delim('}') { |
| 72 | return nil, 0, ErrRecordSequence |
| 73 | } |
| 74 | if _, err := d.Token(); err != io.EOF { |
| 75 | return nil, 0, ErrRecordSequence |
| 76 | } |
| 77 | return fields, seq, nil |
| 78 | } |
| 79 | |
| 80 | // AdvanceRecordSequence alone owns the counter. Callers must preserve the |
| 81 | // read value, including on retries; they cannot reset it or choose a future |
| 82 | // revision. Exhaustion refuses instead of wrapping to a reusable body. |
| 83 | func AdvanceRecordSequence(before, body []byte) ([]byte, error) { |
| 84 | _, base, err := RecordSequence(before) |
| 85 | if err != nil { |
| 86 | return nil, err |
| 87 | } |
| 88 | fields, candidate, err := RecordSequence(body) |
| 89 | if err != nil { |
| 90 | return nil, err |
| 91 | } |
| 92 | if candidate != base { |
| 93 | return nil, ErrRecordSequence |
| 94 | } |
| 95 | if base == ^uint64(0) { |
| 96 | return nil, ErrRecordSequenceExhausted |
| 97 | } |
| 98 | fields["record_seq"] = json.RawMessage(strconv.FormatUint(base+1, 10)) |
| 99 | return json.Marshal(fields) |
| 100 | } |
| 101 | |
| 102 | // preparedRecord binds one synchronous Put to its bytes and CAS base. Store |
| 103 | // wrappers may call WriteRecord again without advancing twice. An inner |
| 104 | // claim boundary can introduce the counter and report the written value back |
| 105 | // to the typed outer writer. This private context grants no write authority. |
| 106 | type preparedRecord struct { |
| 107 | key, etag string |
| 108 | body []byte |
| 109 | base, seq uint64 |
| 110 | sequenced bool |
| 111 | } |
| 112 | |
| 113 | // WriteRecord is the only record-key Put primitive. before is the exact |
| 114 | // If-Match read ({} for create). body preserves that read's counter. Never |
| 115 | // call it with a synthesized before to reset a live record's sequence. |
| 116 | // Legacy absent counters and no claim context retain the exact body bytes. |
| 117 | func WriteRecord(ctx context.Context, s release.Store, key string, before, body []byte, etag string) (string, uint64, error) { |
| 118 | if !IsRecordKey(key) { |
| 119 | return "", 0, ErrRecordSequence |
| 120 | } |
| 121 | fields, base, err := RecordSequence(before) |
| 122 | if err != nil { |
| 123 | return "", 0, err |
| 124 | } |
| 125 | _, candidate, err := RecordSequence(body) |
| 126 | if err != nil { |
| 127 | return "", 0, err |
| 128 | } |
| 129 | enabled, _ := ctx.Value(recordSequenceKey{}).(bool) |
| 130 | _, present := fields["record_seq"] |
| 131 | p, nested := ctx.Value(preparedRecordKey{}).(*preparedRecord) |
| 132 | if nested { |
| 133 | if p.key != key || p.etag != etag || p.base != base || p.seq != candidate || !bytes.Equal(p.body, body) { |
| 134 | return "", 0, ErrRecordSequence |
| 135 | } |
| 136 | } else { |
| 137 | if candidate != base { |
| 138 | return "", 0, ErrRecordSequence |
| 139 | } |
| 140 | p = &preparedRecord{key: key, etag: etag, body: append([]byte(nil), body...), base: base, seq: base} |
| 141 | ctx = context.WithValue(ctx, preparedRecordKey{}, p) |
| 142 | } |
| 143 | if !p.sequenced && (enabled || present) { |
| 144 | body, err = AdvanceRecordSequence(before, body) |
| 145 | if err != nil { |
| 146 | return "", 0, err |
| 147 | } |
| 148 | p.body, p.seq, p.sequenced = append([]byte(nil), body...), base+1, true |
| 149 | } |
| 150 | tag, err := s.Put(ctx, key, body, etag) |
| 151 | return tag, p.seq, err |
| 152 | } |
| 153 | |
amadan