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package swosync
import (
"context"
_ "embed"
"fmt"
"time"
"github.com/target/goalert/swo/swodb"
"github.com/target/goalert/swo/swoinfo"
"github.com/target/goalert/util/sqlutil"
)
//go:embed changelog.sql
var changelogQuery string
func triggerName(table string) string {
return sqlutil.QuoteID(fmt.Sprintf("zz_99_change_log_%s", table))
}
// StartTrackingChanges instruments and begins tracking changes to the DB.
//
// - Creates the change_log table
// - Gets the list of tables and sequences to track
// - Creates the change trigger for each table
// - Disables triggers in the new DB
// - Waits for any in-flight transactions to finish (since these may not have picked up the change trigger)
func (l *LogicalReplicator) StartTrackingChanges(ctx context.Context) error {
l.printf(ctx, "enabling logical replication...")
_, err := l.srcConn.Exec(ctx, changelogQuery)
if err != nil {
return fmt.Errorf("create change_log and fn: %w", err)
}
l.tables, err = swoinfo.ScanTables(ctx, l.srcConn)
if err != nil {
return fmt.Errorf("scan tables: %w", err)
}
l.seqNames, err = swoinfo.ScanSequences(ctx, l.srcConn)
if err != nil {
return fmt.Errorf("scan sequences: %w", err)
}
for _, table := range l.tables {
// create change trigger in source DB
chgTrigQuery := fmt.Sprintf(`
CREATE TRIGGER %s AFTER INSERT OR UPDATE OR DELETE ON %s
FOR EACH ROW EXECUTE PROCEDURE fn_process_change_log()
`, triggerName(table.Name()), sqlutil.QuoteID(table.Name()))
_, err := l.srcConn.Exec(ctx, chgTrigQuery)
if err != nil {
return fmt.Errorf("create change trigger for %s: %w", table.Name(), err)
}
// disable triggers in destination DB
disableTrigQuery := fmt.Sprintf(`ALTER TABLE %s DISABLE TRIGGER USER`, sqlutil.QuoteID(table.Name()))
_, err = l.dstConn.Exec(ctx, disableTrigQuery)
if err != nil {
return fmt.Errorf("disable trigger for %s: %w", table.Name(), err)
}
}
err = swodb.New(l.srcConn).EnableChangeLogTriggers(ctx)
if err != nil {
return fmt.Errorf("enable change log triggers: %w", err)
}
// wait for in-flight transactions to finish
l.printf(ctx, "waiting for in-flight transactions to finish")
db := swodb.New(l.srcConn)
now, err := db.Now(ctx)
if err != nil {
return fmt.Errorf("wait for active tx: get current time: %w", err)
}
for {
n, err := db.ActiveTxCount(ctx, now)
if err != nil {
return fmt.Errorf("wait for active tx: get active tx count: %w", err)
}
if n == 0 {
break
}
l.printf(ctx, "waiting for %d transaction(s) to finish", n)
err = ctxSleep(ctx, time.Second)
if err != nil {
return fmt.Errorf("wait for active tx: sleep: %w", err)
}
}
return nil
}
func ctxSleep(ctx context.Context, dur time.Duration) error {
select {
case <-ctx.Done():
return ctx.Err()
case <-time.After(dur):
}
return nil
}
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