feat: working state syncer

internal/syncer/syncer.go

@@ -0,0 +1,104 @@
+package syncer
+
+import (
+	"context"
+	"log/slog"
+	"time"
+
+	"git.grassecon.net/urdt/ussd-data-connect/internal/store"
+	"git.grassecon.net/urdt/ussd-data-connect/pkg/data"
+	"github.com/georgysavva/scany/v2/pgxscan"
+	"github.com/jackc/pgx/v5"
+)
+
+const syncInterval = time.Second * 10
+
+type (
+	KVRow struct {
+		Key     []byte    `db:"key"`
+		Value   []byte    `db:"value"`
+		Updated time.Time `db:"updated"`
+	}
+
+	SyncerOpts struct {
+		Logg  *slog.Logger
+		Store *store.Store
+	}
+
+	Syncer struct {
+		logg     *slog.Logger
+		interval time.Duration
+		done     chan struct{}
+		store    *store.Store
+	}
+)
+
+func New(o SyncerOpts) *Syncer {
+	return &Syncer{
+		done:     make(chan struct{}),
+		interval: syncInterval,
+		logg:     o.Logg,
+		store:    o.Store,
+	}
+}
+
+func (s *Syncer) Run() {
+	ticker := time.NewTicker(s.interval)
+	s.logg.Info("syncer ticker started")
+	for {
+		select {
+		case <-s.done:
+			ticker.Stop()
+			return
+		case <-ticker.C:
+			s.logg.Debug("syncer tick")
+			if err := s.process(context.Background()); err != nil {
+				s.logg.Error("failed to process sync tick", "error", err)
+			}
+		}
+	}
+}
+
+func (s *Syncer) Stop() {
+	close(s.done)
+}
+
+func (s *Syncer) process(ctx context.Context) error {
+	return s.store.ExecuteTransaction(ctx, func(tx pgx.Tx) error {
+		rows, err := tx.Query(ctx, s.store.Queries.ExtractEntries)
+		if err != nil {
+			return err
+		}
+		defer rows.Close()
+
+		rs := pgxscan.NewRowScanner(rows)
+		var batchTimestamp *time.Time
+		for rows.Next() {
+			var row KVRow
+			if err := rs.Scan(&row); err != nil {
+				return err
+			}
+			if batchTimestamp == nil {
+				batchTimestamp = &row.Updated
+			}
+			decodedKeyDataType, sessionID := data.DecodeKey(row.Key)
+			decodedValue := data.DecodeValue(row.Value)
+
+			if _, ok := data.ValidDataTypeLookup[decodedKeyDataType]; ok {
+				s.logg.Debug("processing row", "batch_timestamp", batchTimestamp, "key_type", decodedKeyDataType, "session_id", sessionID, "value", decodedValue, "timestamp", row.Updated)
+			}
+		}
+		if err := rows.Err(); err != nil {
+			return err
+		}
+
+		if batchTimestamp != nil {
+			_, err = tx.Exec(ctx, s.store.Queries.UpdateCursor, batchTimestamp)
+			if err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+}