| 1 | package host |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "os" |
| 6 | "sync" |
| 7 | "time" |
| 8 | |
| 9 | "github.com/carlosframework/platform/internal/lease" |
| 10 | "github.com/carlosframework/platform/internal/moves" |
| 11 | ) |
| 12 | |
| 13 | // guardedMirror is the one path every staging write takes (moves spec §7.3, |
| 14 | // model 14 and 18): each mutation of the target bucket calls Guarded.Before |
| 15 | // and is signed at the instant the guard checked the staging lease, through |
| 16 | // a lease.StagingWriter whose At methods sign once and never retry. A |
| 17 | // caller that wants another attempt calls again and gets a new check and a |
| 18 | // new signature. |
| 19 | // |
| 20 | // It is a lease.MirrorStore, a VersionedCopier and a VersionedPutter, so |
| 21 | // lease.MirrorPrefixKeep runs over it in its versioned mode. Writes to any |
| 22 | // other bucket are the source's own receipts and ledger in its own bucket: |
| 23 | // they are not staging, need no guard, and go through own, the ordinary |
| 24 | // mirror client. Reads go through the staging writer's ordinary reads. |
| 25 | // Nothing here ever calls a lease.VersionedStore against the target bucket. |
| 26 | type guardedMirror struct { |
| 27 | w lease.StagingWriter |
| 28 | g moves.Guarded |
| 29 | dst string // the target bucket: the only bucket the guard covers |
| 30 | own lease.MirrorStore // the source's own bucket: receipts and the ledger |
| 31 | |
| 32 | // lastSign is the latest signing time the guard handed out through |
| 33 | // this mirror: the cut's seal bound (ruling G7) is computed from it. |
| 34 | mu sync.Mutex |
| 35 | lastSign time.Time |
| 36 | } |
| 37 | |
| 38 | // before is Guarded.Before, recording the signing time it hands out. |
| 39 | func (m *guardedMirror) before(fn func(signAt time.Time) error) error { |
| 40 | return m.g.Before(func(signAt time.Time) error { |
| 41 | m.mu.Lock() |
| 42 | if signAt.After(m.lastSign) { |
| 43 | m.lastSign = signAt |
| 44 | } |
| 45 | m.mu.Unlock() |
| 46 | return fn(signAt) |
| 47 | }) |
| 48 | } |
| 49 | |
| 50 | // lastSigned is the latest signing time handed out, or zero when none was: |
| 51 | // a request signed then can land until lastSigned + moves.SignatureLife. |
| 52 | func (m *guardedMirror) lastSigned() time.Time { |
| 53 | m.mu.Lock() |
| 54 | defer m.mu.Unlock() |
| 55 | return m.lastSign |
| 56 | } |
| 57 | |
| 58 | var ( |
| 59 | _ lease.MirrorStore = (*guardedMirror)(nil) |
| 60 | _ lease.VersionedCopier = (*guardedMirror)(nil) |
| 61 | _ lease.VersionedPutter = (*guardedMirror)(nil) |
| 62 | ) |
| 63 | |
| 64 | func (m *guardedMirror) List(ctx context.Context, bucket, prefix string) (map[string]lease.MirrorObject, error) { |
| 65 | return m.w.List(ctx, bucket, prefix) |
| 66 | } |
| 67 | |
| 68 | func (m *guardedMirror) Get(ctx context.Context, bucket, key string) ([]byte, error) { |
| 69 | if bucket != m.dst { |
| 70 | return m.own.Get(ctx, bucket, key) |
| 71 | } |
| 72 | return m.w.Get(ctx, bucket, key) |
| 73 | } |
| 74 | |
| 75 | func (m *guardedMirror) CopyVersioned(ctx context.Context, srcBucket, srcKey, srcETag, dstBucket, dstKey string) (etag, versionID string, err error) { |
| 76 | err = m.before(func(signAt time.Time) error { |
| 77 | var cerr error |
| 78 | etag, versionID, cerr = m.w.CopyVersionedAt(ctx, signAt, srcBucket, srcKey, srcETag, dstBucket, dstKey) |
| 79 | return cerr |
| 80 | }) |
| 81 | return etag, versionID, err |
| 82 | } |
| 83 | |
| 84 | // Copy is CopyVersioned without the version. MirrorPrefixKeep never calls |
| 85 | // it on a VersionedCopier; it exists so the type is a MirrorStore. |
| 86 | func (m *guardedMirror) Copy(ctx context.Context, srcBucket, srcKey, srcETag, dstBucket, dstKey string) (string, error) { |
| 87 | etag, _, err := m.CopyVersioned(ctx, srcBucket, srcKey, srcETag, dstBucket, dstKey) |
| 88 | return etag, err |
| 89 | } |
| 90 | |
| 91 | func (m *guardedMirror) PutVersioned(ctx context.Context, bucket, key string, body []byte) (versionID string, err error) { |
| 92 | err = m.before(func(signAt time.Time) error { |
| 93 | var perr error |
| 94 | versionID, perr = m.w.PutVersionedAt(ctx, signAt, bucket, key, body) |
| 95 | return perr |
| 96 | }) |
| 97 | return versionID, err |
| 98 | } |
| 99 | |
| 100 | // PutFileVersioned stages the file at path (size bytes, sha256Hex) as key, |
| 101 | // read from disk inside the guarded call: a retry opens it again under a |
| 102 | // new check. |
| 103 | func (m *guardedMirror) PutFileVersioned(ctx context.Context, bucket, key, path string, size int64, sha256Hex string) (versionID string, err error) { |
| 104 | err = m.before(func(signAt time.Time) error { |
| 105 | f, oerr := os.Open(path) |
| 106 | if oerr != nil { |
| 107 | return oerr |
| 108 | } |
| 109 | defer f.Close() |
| 110 | var perr error |
| 111 | versionID, perr = m.w.PutReaderVersionedAt(ctx, signAt, bucket, key, f, size, sha256Hex) |
| 112 | return perr |
| 113 | }) |
| 114 | return versionID, err |
| 115 | } |
| 116 | |
| 117 | // PutIfAbsentVersioned is move.json's create-only write; an existing object |
| 118 | // is lease.ErrExists. |
| 119 | func (m *guardedMirror) PutIfAbsentVersioned(ctx context.Context, bucket, key string, body []byte) (versionID string, err error) { |
| 120 | err = m.before(func(signAt time.Time) error { |
| 121 | var perr error |
| 122 | versionID, perr = m.w.PutIfAbsentVersionedAt(ctx, signAt, bucket, key, body) |
| 123 | return perr |
| 124 | }) |
| 125 | return versionID, err |
| 126 | } |
| 127 | |
| 128 | func (m *guardedMirror) Put(ctx context.Context, bucket, key string, body []byte) error { |
| 129 | if bucket != m.dst { |
| 130 | return m.own.Put(ctx, bucket, key, body) |
| 131 | } |
| 132 | _, err := m.PutVersioned(ctx, bucket, key, body) |
| 133 | return err |
| 134 | } |
| 135 | |
| 136 | func (m *guardedMirror) Delete(ctx context.Context, bucket, key string) error { |
| 137 | if bucket != m.dst { |
| 138 | return m.own.Delete(ctx, bucket, key) |
| 139 | } |
| 140 | return m.before(func(signAt time.Time) error { |
| 141 | return m.w.DeleteAt(ctx, signAt, bucket, key) |
| 142 | }) |
| 143 | } |
| 144 | |
amadan