snapshot_worker_state.go Raw History Folder

1package daemon
2
3import (
4	"context"
5	"sync"
6)
7
8// snapshotWorker owns the state of the repository snapshot worker and of the
9// other durable writers joined with it (maintenance and restoration), so
10// WaitDurableWriters can read all three completion signals under one lock.
11//
12// Lock position: mu is a leaf with respect to Daemon.mu and the session (mu),
13// tab, and pane locks: no path acquires any of them while holding it, and
14// capture, queue, and worker code never takes Daemon.mu. The one nested lock is
15// a session's snapshotMu, taken under mu by enqueueFinalSnapshotCapture; see
16// the lock-ordering notes in client.go. noticeMu is a leaf and is never held
17// together with mu.
18//
19// The zero value is usable for tests that build &Daemon{}: nil maps are
20// allocated lazily by the enqueue paths, and a nil jobs channel never becomes
21// ready in a select.
22type snapshotWorker struct {
23	// jobs is the bounded regular capture queue. It is never closed: producers
24	// can race shutdown without risking a send-on-closed panic.
25	jobs chan *snapshotCapture
26	// wake wakes the repository scheduler when a session becomes dirty
27	// or an attempt completes. It is never closed and producers only send
28	// non-blockingly.
29	wake chan struct{}
30
31	// mu guards every field below it.
32	mu sync.Mutex
33	// admitted contains every capture accepted by either worker queue,
34	// including captures buffered in jobs.
35	admitted  map[*snapshotCapture]struct{}
36	id        uint64
37	ctx       context.Context
38	cancel    context.CancelFunc
39	done      chan struct{}
40	flush     chan struct{}
41	finalWake chan struct{}
42	// finalJobs coalesces terminal captures by session when the bounded
43	// regular queue is full. It retains at most snapshotFinalQueueCapacity named
44	// sessions, each with only its newest terminal state while the worker blocks.
45	finalJobs  map[*session]*snapshotCapture
46	finalOrder []*session
47	closing    bool
48	inFlight   *snapshotCapture
49
50	// maintenanceWorkerCancel/Done and restoreWorkerDone are the other durable
51	// writers' ownership signals. They share mu with the snapshot worker and are
52	// joined together in WaitDurableWriters; never split them. Startup
53	// restoration reconciles durable checkpoints, so it is a durable writer.
54	maintenanceWorkerCancel context.CancelFunc
55	maintenanceWorkerDone   chan struct{}
56	restoreWorkerDone       chan struct{}
57
58	// noticeMu guards the active global persistence failure signature. It is
59	// separate from mu so notice routing cannot block a producer or a
60	// repository worker.
61	noticeMu               sync.Mutex
62	activeFailureSignature string
63}

snapshot_worker_state.go RawHistoryFolder

snapshot_worker_state.go Raw History Folder