datasync

type Runner struct {
	// contains filtered or unexported fields
}

type Sync struct {
	SourceDSN       string        `name:"source-dsn" help:"Where to sync the tables from." default:"spirit:spirit@tcp(127.0.0.1:3306)/src"`
	TargetDSN       string        `name:"target-dsn" help:"Where to sync the tables to." default:"spirit:spirit@tcp(127.0.0.1:3306)/dest"`
	TargetChunkTime time.Duration `name:"target-chunk-time" help:"How long each copy chunk should take." default:"5s"`
	Threads         int           `name:"threads" help:"How many chunks to copy in parallel during the initial copy." default:"4"`
	WriteThreads    int           `name:"write-threads" help:"How many concurrent write threads to use on the target." default:"4"`
	// FlushInterval controls how often buffered changes are applied to the
	// target during continuous sync — i.e. the replication latency vs.
	// batching trade-off. Defaults to change.DefaultFlushInterval.
	FlushInterval time.Duration `name:"flush-interval" help:"How often to flush buffered changes to the target during continuous sync." default:"30s"`

	// CopyOnly performs only the initial copy and then returns — no change
	// capture and no continuous replication, so no change.Source is
	// constructed or required. Useful for a one-shot snapshot, or when the
	// source cannot provide a change feed (e.g. a managed Vitess without
	// binlog/VStream access, or a replica lacking the REPLICATION privileges
	// the built-in binlog client needs). A final checkpoint is still written,
	// so a later run resumes the copy from there (or no-ops if it had already
	// completed) rather than starting over.
	CopyOnly bool `name:"copy-only" help:"Only run the initial copy, then exit (no continuous change capture)." default:"false"`

	// Force, when set, makes the runner drop and recreate the target database
	// at startup *unless* a resumable checkpoint exists — i.e. it only nukes
	// the target when the copy could not have resumed anyway. A resumable
	// run (checkpoint present) is left intact and resumes as normal. Intended
	// for testing/iterating, where a previous partial run can leave the target
	// non-empty with no usable checkpoint, otherwise tripping the fresh-sync
	// target-empty guard.
	Force bool `name:"force" help:"Drop and recreate the target database when the copy cannot resume from a checkpoint." default:"false"`

	// GTID switches the built-in change source from binlog file+position to
	// MySQL GTIDs. EXPERIMENTAL — see pkg/change/gtid.go. Ignored when a
	// pre-constructed Source is injected. Requires gtid_mode=ON and
	// enforce_gtid_consistency=ON on the source.
	GTID bool `name:"gtid" help:"EXPERIMENTAL: use GTID-based change source instead of binlog file+position" default:"false"`

	// Source optionally provides a pre-constructed change.Source to use
	// for replication instead of constructing a built-in MySQL-binlog
	// client from SourceDSN. When set, the runner uses this as the change
	// feed. SourceDSN is still required for source-side SQL (SHOW TABLES,
	// SHOW CREATE TABLE, the initial-copy SELECTs). Setting Source requires
	// setting Applier (see below).
	//
	// Intended for callers (e.g. strata's Vitess/PlanetScale import) that
	// need a non-MySQL-binlog change source.
	Source change.Source `kong:"-"`

	// Applier optionally provides a pre-constructed applier.Applier. When
	// set, the runner uses this instead of constructing a MySQL
	// SingleTargetApplier from the target. Required when Source is set: the
	// injected change.Source needs the same applier instance the copier
	// uses, so all writes flow through one logical apply path.
	Applier applier.Applier `kong:"-"`

	// Target optionally supplies a pre-opened target. When nil, a single
	// MySQL target is opened from TargetDSN (auto-creating the database if
	// it does not exist). Sync writes to exactly one logical target — there
	// is no N:M fan-out.
	Target *applier.Target `kong:"-"`
}