| 1 | package hostguard |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "strconv" |
| 6 | "strings" |
| 7 | |
| 8 | "github.com/carlosframework/platform/internal/hostclaim" |
| 9 | ) |
| 10 | |
| 11 | // writerStopPrefix marks the obligation component of an operation stop that |
| 12 | // names the operation's own admitted writer session, not a chore (claim Plan |
| 13 | // 9 D4). A landing target stops its probe before a restarted probe or a cold |
| 14 | // wake is admitted; no chore exists for that, and none is invented. |
| 15 | const writerStopPrefix = "writer-session-" |
| 16 | |
| 17 | // WriterStopObligation is the obligation component with which an operation's |
| 18 | // executor stops writer session s under that operation. It is deterministic, |
| 19 | // so a repeated request for the same session meets the same fence and |
| 20 | // receipt, and every later session gets its own. |
| 21 | func WriterStopObligation(session uint64) string { |
| 22 | return writerStopPrefix + strconv.FormatUint(session, 10) |
| 23 | } |
| 24 | |
| 25 | func writerStop(obligation string) bool { |
| 26 | return strings.HasPrefix(obligation, writerStopPrefix) |
| 27 | } |
| 28 | |
| 29 | // LandingWriter returns the admission of the claim's current writer session |
| 30 | // when that session is box's own landing writer: the op is a landing at a |
| 31 | // phase of the landing's session row (probing, probed, committed; claim Plan |
| 32 | // 9 D1), box executes it and is holder.writer_box, and the session was |
| 33 | // admitted exactly once, cold, on box, into the held generation. A landing's |
| 34 | // first probe, whose predecessor is the source's session on another box, is |
| 35 | // never box's writer here. |
| 36 | func LandingWriter(c *hostclaim.Claim, box string) (hostclaim.AdmissionRecord, bool) { |
| 37 | return operationWriter(c, box, hostclaim.KindLanding) |
| 38 | } |
| 39 | |
| 40 | func operationWriter(c *hostclaim.Claim, box, kind string) (hostclaim.AdmissionRecord, bool) { |
| 41 | if c == nil || c.Holder == nil || box == "" || c.Holder.Session == 0 { |
| 42 | return hostclaim.AdmissionRecord{}, false |
| 43 | } |
| 44 | h := c.Holder |
| 45 | if c.Op.Kind != kind || c.Op.ID == "" || c.Op.Exec != box || h.WriterBox != box || |
| 46 | !hostclaim.SessionPhase(kind, c.Op.Phase) { |
| 47 | return hostclaim.AdmissionRecord{}, false |
| 48 | } |
| 49 | var found hostclaim.AdmissionRecord |
| 50 | matched := 0 |
| 51 | for _, a := range h.Admissions { |
| 52 | if a.Session == h.Session { |
| 53 | if a.Box != box || a.Mode != "cold" || a.Generation != h.Generation { |
| 54 | return hostclaim.AdmissionRecord{}, false |
| 55 | } |
| 56 | found = a |
| 57 | matched++ |
| 58 | } |
| 59 | } |
| 60 | return found, matched == 1 |
| 61 | } |
| 62 | |
| 63 | // LandingWriterStop is the obligation component with which box may ask root |
| 64 | // to stop the claim's current writer session as the landing's own writer: |
| 65 | // LandingWriter holds, the session was admitted in region, and no chore of |
| 66 | // the claim carries the same id. Any other claim has no writer stop. |
| 67 | func LandingWriterStop(c *hostclaim.Claim, box, region string) (string, bool) { |
| 68 | return operationWriterStop(c, box, region, hostclaim.KindLanding) |
| 69 | } |
| 70 | |
| 71 | // RelocationWriterStop authorizes only this box's admitted relocation writer. |
| 72 | func RelocationWriterStop(c *hostclaim.Claim, box, region string) (string, bool) { |
| 73 | return operationWriterStop(c, box, region, hostclaim.KindRelocating) |
| 74 | } |
| 75 | |
| 76 | func operationWriterStop(c *hostclaim.Claim, box, region, kind string) (string, bool) { |
| 77 | a, ok := operationWriter(c, box, kind) |
| 78 | if !ok || region == "" || a.Region != region { |
| 79 | return "", false |
| 80 | } |
| 81 | id := WriterStopObligation(c.Holder.Session) |
| 82 | for _, o := range c.Obligations { |
| 83 | if o.ID == id { |
| 84 | return "", false |
| 85 | } |
| 86 | } |
| 87 | return id, true |
| 88 | } |
| 89 | |
| 90 | // CompletedWriterStops returns every completed writer-session stop journalled |
| 91 | // for exactly the captured installation, under op, on box. Fence receipts are |
| 92 | // append-only, so a receipt returned here stays effective. |
| 93 | func (g Guard) CompletedWriterStops(ctx context.Context, host string, captured Captured, op, box string) ([]FenceReceipt, error) { |
| 94 | if ctx == nil || captured.Incarnation == "" || captured.Stamp == 0 || op == "" || box == "" { |
| 95 | return nil, ErrInvalidInput |
| 96 | } |
| 97 | var out []FenceReceipt |
| 98 | err := g.fenceLocked(ctx, host, captured, func(d *recordDir) error { |
| 99 | r, err := d.read(host) |
| 100 | if err != nil { |
| 101 | return err |
| 102 | } |
| 103 | for _, receipt := range r.FenceJournal { |
| 104 | t := receipt.Target |
| 105 | if t.Host == host && t.Incarnation == captured.Incarnation && t.Stamp == captured.Stamp && t.Op == op && t.Box == box && t.ObligationID == WriterStopObligation(t.Session) { |
| 106 | out = append(out, receipt) |
| 107 | } |
| 108 | } |
| 109 | return nil |
| 110 | }) |
| 111 | return out, err |
| 112 | } |
| 113 | |
| 114 | // CompletedServingStops selects completed stops for one serving installation. |
| 115 | // Operation receipts cannot stand in for a serving stop. |
| 116 | func (g Guard) CompletedServingStops(ctx context.Context, host string, captured Captured, session uint64, box string) ([]FenceReceipt, error) { |
| 117 | if ctx == nil || host == "" || captured.Incarnation == "" || captured.Stamp == 0 || session == 0 || box == "" { |
| 118 | return nil, ErrInvalidInput |
| 119 | } |
| 120 | var out []FenceReceipt |
| 121 | err := g.fenceLocked(ctx, host, captured, func(d *recordDir) error { |
| 122 | r, err := d.read(host) |
| 123 | if err != nil { |
| 124 | return err |
| 125 | } |
| 126 | for _, receipt := range r.FenceJournal { |
| 127 | t := receipt.Target |
| 128 | if t.Host != host || t.Incarnation != captured.Incarnation || t.Stamp != captured.Stamp || t.Box != box || t.Op != "" || t.Phase != "" || t.ObligationID != "" { |
| 129 | continue |
| 130 | } |
| 131 | if t.Session != session { |
| 132 | return ErrNoFenceReceipt |
| 133 | } |
| 134 | out = append(out, receipt) |
| 135 | } |
| 136 | if len(out) == 0 { |
| 137 | return ErrNoFenceReceipt |
| 138 | } |
| 139 | return nil |
| 140 | }) |
| 141 | if err != nil { |
| 142 | return nil, err |
| 143 | } |
| 144 | return out, nil |
| 145 | } |
| 146 | |
| 147 | func RecoveryWriter(c *hostclaim.Claim, box string) (hostclaim.AdmissionRecord, bool) { |
| 148 | if c == nil || (c.Op.Kind != hostclaim.KindRestoring && c.Op.Kind != hostclaim.KindReverting) || c.Op.Intent["source"] != box { |
| 149 | return hostclaim.AdmissionRecord{}, false |
| 150 | } |
| 151 | return operationWriter(c, box, c.Op.Kind) |
| 152 | } |
| 153 | func RecoveryWriterStop(c *hostclaim.Claim, box, region string) (string, bool) { |
| 154 | if c != nil && c.Holder != nil && region != "" && box != "" && (c.Op.Kind == hostclaim.KindRestoring || c.Op.Kind == hostclaim.KindReverting) && c.Op.ID != "" && c.Op.Phase == hostclaim.PhaseProbing && c.Op.Exec == box && c.Op.Intent["source"] == box { |
| 155 | h := c.Holder |
| 156 | stamp, err := strconv.ParseUint(c.Op.Journal[hostclaim.JournalSourceStamp], 10, 64) |
| 157 | if err == nil && stamp > 0 && h.Stamp == stamp && h.Session == 0 && h.Generation == "" && h.WriterBox == "" && len(h.Admissions) == 0 && c.Op.Journal[hostclaim.JournalCutSession] == "0" && c.Op.Journal[hostclaim.JournalSrcGen] == "" { |
| 158 | id := WriterStopObligation(0) |
| 159 | for _, ob := range c.Obligations { |
| 160 | if ob.ID == id { |
| 161 | return "", false |
| 162 | } |
| 163 | } |
| 164 | return id, true |
| 165 | } |
| 166 | } |
| 167 | if _, ok := RecoveryWriter(c, box); !ok { |
| 168 | return "", false |
| 169 | } |
| 170 | return operationWriterStop(c, box, region, c.Op.Kind) |
| 171 | } |
| 172 | |
amadan