[golang] rewrite database handling

golang/pkg/database/db.go

@@ -3,17 +3,123 @@ package database
 import (
 	"context"
 	"database/sql"
+	"fmt"
+	"runtime"
 )
 
+func initDB(ctx context.Context, url string) (*sql.DB, error) {
+	db, err := sql.Open("sqlite3", url)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open database: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			_ = db.Close()
+		}
+	}()
+	if _, err = db.ExecContext(ctx, "PRAGMA busy_timeout = 5000"); err != nil {
+		return nil, fmt.Errorf("failed to set pragma: %w", err)
+	}
+
+	return db, nil
+}
+
 type DB struct {
-	ctx context.Context
-	db  *sql.DB
+	ctx     context.Context
+	readDB  *sql.DB
+	writeDB *sql.DB
+}
+
+func NewDB(ctx context.Context, url string) (*DB, error) {
+	readDB, err := initDB(ctx, url)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init read database connection: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			_ = readDB.Close()
+		}
+	}()
+	readDB.SetMaxOpenConns(max(4, runtime.NumCPU()))
+
+	writeDB, err := initDB(ctx, url)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init write database connection: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			_ = writeDB.Close()
+		}
+	}()
+	writeDB.SetMaxOpenConns(1)
+
+	db := DB{
+		ctx:     ctx,
+		readDB:  readDB,
+		writeDB: writeDB,
+	}
+	pragmas := []struct {
+		key   string
+		value string
+	}{
+		{"foreign_keys", "ON"},
+		{"cache_size", "10000000"},
+		{"journal_mode", "WAL"},
+		{"synchronous", "NORMAL"},
+	}
+	for _, pragma := range pragmas {
+		if _, err = db.Exec(fmt.Sprintf("PRAGMA %s = %s", pragma.key, pragma.value)); err != nil {
+			return nil, fmt.Errorf("failed to set pragma: %w", err)
+		}
+	}
+	if err = db.migrate(); err != nil {
+		return nil, fmt.Errorf("failed to migrate: %w", err)
+	}
+
+	return &db, nil
+}
+
+func (db *DB) Close() error {
+	if err := db.readDB.Close(); err != nil {
+		_ = db.writeDB.Close()
+		return fmt.Errorf("failed to close read database connection: %w", err)
+	}
+	if err := db.writeDB.Close(); err != nil {
+		return fmt.Errorf("failed to close write database connection: %w", err)
+	}
+	return nil
 }
 
 func (db *DB) Exec(query string, args ...any) (sql.Result, error) {
-	return db.db.ExecContext(db.ctx, query, args...)
+	return db.writeDB.ExecContext(db.ctx, query, args...)
+}
+
+func (db *DB) Query(query string, args ...any) (*sql.Rows, error) {
+	return db.readDB.QueryContext(db.ctx, query, args...)
 }
 
 func (db *DB) QueryRow(query string, args ...any) *sql.Row {
-	return db.db.QueryRowContext(db.ctx, query, args...)
+	return db.readDB.QueryRowContext(db.ctx, query, args...)
+}
+
+func (db *DB) WithTransaction(f func(tx *sql.Tx) error) error {
+	tx, err := db.writeDB.Begin()
+	if err != nil {
+		return fmt.Errorf("failed to begin transaction: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			if err2 := tx.Rollback(); err2 != nil {
+				panic(fmt.Sprintf("failed to rollback transaction: %+v. Reason for rollback: %+v", err2, err))
+			}
+		}
+	}()
+	if err = f(tx); err != nil {
+		return fmt.Errorf("failed to execute function inside transaction: %w", err)
+	} else {
+		if err = tx.Commit(); err != nil {
+			err = fmt.Errorf("failed to commit transaction: %w", err)
+		}
+	}
+	return err
 }