Documentation
¶
Overview ¶
Package app holds the use cases of Arnakoff and the ports they consume. It depends on domain only (ADR 0002).
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrUnknownSource = errors.New("unknown source") ErrDuplicateSource = errors.New("duplicate source") )
Sync errors, checked with errors.Is.
var ErrInterval = errors.New("sync interval must be positive")
ErrInterval means a plan has no positive interval.
var ErrNoSnapshot = errors.New("no stored snapshot")
ErrNoSnapshot is returned by SnapshotStore.Load when it holds no snapshot of the source.
Functions ¶
This section is empty.
Types ¶
type Alerter ¶ added in v0.19.0
Alerter tells the operator that a source could not be synced or reloaded. It reports its own failures: the caller has nothing to do about them.
type Jitter ¶ added in v0.19.0
Jitter returns a random duration from 0 up to, but not including, max.
type Reloader ¶ added in v0.19.0
type Reloader struct {
// contains filtered or unexported fields
}
Reloader restores, at an interval, the snapshots the sync process stored, so that the API process serves them without a restart. It alerts when a source starts failing to reload, not again until it has recovered.
func NewReloader ¶ added in v0.19.0
NewReloader returns a Reloader of the sources of s, checking every interval.
type Scheduler ¶ added in v0.19.0
type Scheduler struct {
// contains filtered or unexported fields
}
Scheduler syncs each planned source at its interval, plus a jitter, and alerts on every sync that fails or is rejected.
func NewScheduler ¶ added in v0.19.0
func NewScheduler(s *Sync, sleeper Sleeper, alerter Alerter, jitter Jitter, plans ...Plan) (*Scheduler, error)
NewScheduler returns a Scheduler of plans, or ErrUnknownSource, ErrDuplicateSource or ErrInterval for a plan s cannot follow.
func (*Scheduler) Once ¶ added in v0.19.0
Once syncs each of sources once, or every planned source when none is given, alerts on each failure and joins the errors. It returns ErrUnknownSource without syncing anything when a source is not planned.
type Sleeper ¶ added in v0.19.0
type Sleeper interface {
// Sleep returns after d, or with the error of ctx once it is done.
Sleep(ctx context.Context, d time.Duration) error
}
Sleeper pauses a scheduling loop; tests inject one that does not wait.
type SnapshotStore ¶
type SnapshotStore interface {
// Save durably replaces the stored snapshot of s.Source.
Save(ctx context.Context, s domain.Snapshot) error
// Load returns the stored snapshot of source, or ErrNoSnapshot.
Load(ctx context.Context, source domain.Source) (domain.Snapshot, error)
}
SnapshotStore keeps the last valid snapshot of each source across restarts and between the sync and API processes.
func DryRun ¶ added in v0.19.0
func DryRun(st SnapshotStore) SnapshotStore
DryRun returns a store that reads st and keeps nothing: a Sync on it, once restored, validates new snapshots against the stored ones without replacing them.
type SourceFetcher ¶
type SourceFetcher interface {
// Spec declares the source and what a sane file of it holds.
Spec() domain.SnapshotSpec
// Fetch downloads the source and parses it into a snapshot. Sync sets
// its FetchedAt.
Fetch(ctx context.Context) (domain.Snapshot, error)
}
SourceFetcher downloads and parses one upstream source.
type SourceSync ¶
type SourceSync struct {
Source domain.Source
// LastSuccess is when the snapshot in service was fetched, zero when
// none is.
LastSuccess time.Time
// LastFailure is when the last failed or rejected sync ran, zero when
// none did. It is kept after a later success.
LastFailure time.Time
// LastError is why that sync failed.
LastError error
// Rows is the number of rows of the snapshot in service.
Rows int
// Newest is the date of the most recent entry in service, zero when the
// source dates none.
Newest time.Time
}
SourceSync is the sync state of one source, as /v1/sources shows it.
type Sync ¶
type Sync struct {
// contains filtered or unexported fields
}
Sync downloads each source, validates the new snapshot against the connector's spec and the last valid one, stores it, then swaps it in for the readers. A rejected snapshot leaves the last valid one in service. It is safe for concurrent use.
func NewSync ¶
func NewSync(store SnapshotStore, clock Clock, fetchers ...SourceFetcher) (*Sync, error)
NewSync returns a Sync of the sources the fetchers declare, or ErrDuplicateSource when two declare the same one.
func (*Sync) Restore ¶
Restore puts in service the stored snapshot of every source when it is valid and newer than the one in service. It runs at startup, and in the API process to pick up what the sync process stored. A source with no stored snapshot is skipped; errors of the others are joined.
func (*Sync) Run ¶
Run syncs every source in turn and joins their errors: one source failing does not stop the others.
func (*Sync) Snapshot ¶
Snapshot returns the snapshot in service for source, if any. It is shared with every reader: treat it as read-only.
func (*Sync) States ¶
func (s *Sync) States() []SourceSync
States returns the sync state of every source, in declaration order.