snapshot.go RawHistoryFolder

1package daemon
2
3import (
4	"context"
5	"errors"
6	"fmt"
7	"sync"
8	"time"
9
10	vt "github.com/bnema/vev-vt"
11	"github.com/bnema/vev/internal/domain"
12	"github.com/bnema/vev/internal/usecase/layout"
13	snapcodec "github.com/bnema/vev/internal/usecase/snapshot"
14)
15
16// snapshotQueueCapacity bounds retained immutable captures. A full queue never
17// stalls session producers; the session remains dirty for the next interval.
18const snapshotQueueCapacity = 1
19
20// snapshotFinalQueueCapacity is a global bound for terminal captures retained
21// while the worker is blocked. On saturation a new terminal capture is rejected
22// (and left dirty) rather than silently dropping a persistence acknowledgement.
23const snapshotFinalQueueCapacity = 32
24
25// snapshotAttemptKind distinguishes rate-limited routine publications from
26// mandatory terminal checkpoints. Forced attempts never consume the routine
27// completion window.
28type snapshotAttemptKind uint8
29
30const (
31	snapshotAttemptRoutine snapshotAttemptKind = iota
32	snapshotAttemptForced
33)
34
35type snapshotCapture struct {
36	session              *session
37	attemptKind          snapshotAttemptKind
38	generation           uint64 // repository publication generation
39	parentCheckpoint     *domain.CheckpointRef
40	checkpoint           domain.CheckpointRef // set by the encoder before publication
41	mutationRevision     uint64
42	name                 string
43	incarnation          domain.IncarnationID
44	createdAt            uint64
45	defaultTab           uint16
46	tabs                 []snapshotCaptureTab
47	publicationContext   context.Context
48	sealedRefs           map[*vt.HistoryChunk]snapcodec.ObjectRef // set by the single encoder worker
49	coordinatorDiscarded bool                                     // guarded by session.snapshotMu
50	// normalWorkerAdmitted is set before snapshotJobs admission and immutable
51	// until completion; final-queue captures leave it false.
52	normalWorkerAdmitted bool
53	finishOnce           sync.Once
54}
55
56type snapshotCaptureTab struct {
57	stableID   string
58	cols       uint16
59	rows       uint16
60	nextPaneID uint64
61	focus      layout.PaneID
62	tree       *layout.Tree
63	panes      []snapshotCapturePane
64}
65
66type snapshotCapturePane struct {
67	id       layout.PaneID
68	stableID string
69	cwd      string
70	// Sealed identities and the copied mutable tail are retained separately, so
71	// capture never rotates a live mutable tail merely to persist it.
72	sealed vt.HistorySnapshotView
73	tail   vt.HistoryView
74	// transcript is an owned copy taken while pane.mu is held. It must be
75	// marshaled only after that lock has been released.
76	transcript vt.RecoveryTranscriptSnapshot
77	process    *snapcodec.Process
78}
79
80// snapshotFailureSignature classifies a persistence failure without retaining
81// error text. Error strings often contain object content or filesystem paths,
82// neither of which is stable enough for deduplication or suitable for a global
83// notice history.
84func snapshotFailureSignature(phase string, err error) string {
85	if err == nil {
86		return phase + ":none"
87	}
88	switch {
89	case errors.Is(err, context.Canceled):
90		return phase + ":canceled"
91	case errors.Is(err, context.DeadlineExceeded):
92		return phase + ":deadline"
93	default:
94		return fmt.Sprintf("%s:%T", phase, err)
95	}
96}
97
98const (
99	// Routine checkpoints are rate limited from completion; forced teardown
100	// checkpoints use the same bounded worker but never consume this window.
101	snapshotInterval          = 2 * time.Minute
102	snapshotFinalFlushTimeout = time.Second
103)
104
105// SnapshotShutdownTimeout reports the shared final-checkpoint shutdown budget.
106func SnapshotShutdownTimeout() time.Duration { return snapshotFinalFlushTimeout }