Initial Commit

pkg/dbwait/dbwait.go

@@ -0,0 +1,65 @@
+package dbwait
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"net/url"
+	"os"
+	"time"
+)
+
+func Wait(databaseURL *url.URL, period time.Duration, timeout time.Duration) error {
+	var err error
+	var sqlDB *sql.DB
+
+	switch databaseURL.Scheme {
+	case "oracle":
+		sqlDB, err = sql.Open("oracle", databaseURL.String())
+		if err != nil {
+			return err
+		}
+	case "postgres":
+		sqlDB, err = sql.Open("postgres", databaseURL.String())
+		if err != nil {
+			return err
+		}
+	}
+	defer sqlDB.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	ticker := time.NewTicker(time.Nanosecond)
+	<-ticker.C
+
+LOOP:
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-ticker.C:
+			queryCtx, queryCancel := context.WithTimeout(ctx, period)
+			defer queryCancel()
+
+			switch databaseURL.Scheme {
+			case "oracle":
+				_, err := sqlDB.QueryContext(queryCtx, "SELECT 1 FROM dual")
+				if err != nil {
+					fmt.Fprintf(os.Stderr, "%s: %s\n", time.Now().String(), err.Error())
+					ticker.Reset(period)
+					continue LOOP
+				}
+				return nil
+			case "postgres":
+				_, err := sqlDB.QueryContext(queryCtx, "SELECT 1 AS ROW")
+				if err != nil {
+					fmt.Fprintf(os.Stderr, "%s: %s\n", time.Now().String(), err.Error())
+					ticker.Reset(period)
+					continue LOOP
+				}
+				return nil
+			}
+		}
+	}
+}