basic online

internal/database/db.go

@@ -0,0 +1,42 @@
+package database
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	_ "modernc.org/sqlite"
+)
+
+// DB wraps sql.DB so the rest of the codebase has a single type to depend on.
+type DB struct {
+	*sql.DB
+}
+
+// Connect opens (or creates) the SQLite file at path and runs pragmas for
+// safe, performant operation. Pass ":memory:" for tests.
+func Connect(_ context.Context, path string) (*DB, error) {
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		return nil, fmt.Errorf("open sqlite: %w", err)
+	}
+
+	// WAL mode gives much better read concurrency without blocking reads
+	// during writes. foreign_keys must be enabled per-connection in SQLite.
+	pragmas := []string{
+		"PRAGMA journal_mode=WAL;",
+		"PRAGMA foreign_keys=ON;",
+		"PRAGMA busy_timeout=5000;",
+	}
+	for _, p := range pragmas {
+		if _, err := db.Exec(p); err != nil {
+			return nil, fmt.Errorf("pragma %q: %w", p, err)
+		}
+	}
+
+	if err := db.Ping(); err != nil {
+		return nil, fmt.Errorf("ping sqlite: %w", err)
+	}
+
+	return &DB{db}, nil
+}