[golang] rewrite database handling

3 files changed, 134 insertions, 54 deletions

diff --git a/golang/cmd/spacetraders/main.go b/golang/cmd/spacetraders/main.go
index 84d34ea..e97cc32 100644
--- a/golang/cmd/spacetraders/main.go
+++ b/golang/cmd/spacetraders/main.go
@@ -26,7 +26,10 @@ func main() {
 	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer cancel()
 
-	db, err := database.DBInit(ctx, "./spacetraders.db")
+	db, err := database.NewDB(
+		ctx,
+		"./spacetraders.db?_txlock=immediate",
+	)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "DbInit error %+v\n", err)
 		os.Exit(1)
diff --git a/golang/pkg/database/db.go b/golang/pkg/database/db.go
index 3e07db3..cb15e52 100644
--- a/golang/pkg/database/db.go
+++ b/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
 }
diff --git a/golang/pkg/database/migrations.go b/golang/pkg/database/migrations.go
index b167087..31cc3d3 100644
--- a/golang/pkg/database/migrations.go
+++ b/golang/pkg/database/migrations.go
@@ -1,7 +1,6 @@
 package database
 
 import (
-	"context"
 	"database/sql"
 	"embed"
 	"io/fs"
@@ -12,35 +11,9 @@ import (
 //go:embed sql/*.sql
 var schemaFiles embed.FS
 
-func DBInit(ctx context.Context, url string) (myDB *DB, err error) {
-	var db *sql.DB
-	if db, err = sql.Open("sqlite3", url); err != nil {
-		return nil, err
-	}
-	defer func() {
-		if err != nil {
-			_ = db.Close()
-		}
-	}()
-
-	if _, err = db.ExecContext(ctx, "PRAGMA foreign_keys = ON"); err != nil {
-		return nil, err
-	}
-	if _, err = db.ExecContext(ctx, "PRAGMA journal_mode = WAL"); err != nil {
-		return nil, err
-	}
-
-	var version int
-	if err = db.QueryRowContext(ctx, `SELECT version FROM schema_version;`).Scan(&version); err != nil {
-		if err.Error() == "no such table: schema_version" {
-			version = 0
-		} else {
-			return nil, err
-		}
-	}
-
+func (db *DB) migrate() error {
 	statements := make([]string, 0)
-	err = fs.WalkDir(schemaFiles, ".", func(path string, d fs.DirEntry, err error) error {
+	err := fs.WalkDir(schemaFiles, ".", func(path string, d fs.DirEntry, err error) error {
 		if d.IsDir() || err != nil {
 			return err
 		}
@@ -53,28 +26,26 @@ func DBInit(ctx context.Context, url string) (myDB *DB, err error) {
 		return nil
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	tx, err := db.Begin()
-	if err != nil {
-		return nil, err
-	}
-	for version < len(statements) {
-		if _, err = tx.ExecContext(ctx, statements[version]); err != nil {
-			tx.Rollback()
-			return nil, err
+	return db.WithTransaction(func(tx *sql.Tx) error {
+		var version int
+		if err = tx.QueryRowContext(db.ctx, `SELECT version FROM schema_version;`).Scan(&version); err != nil {
+			if err.Error() == "no such table: schema_version" {
+				version = 0
+			} else {
+				return err
+			}
 		}
-		version++
-	}
-	if _, err = tx.ExecContext(ctx, `DELETE FROM schema_version; INSERT INTO schema_version (version) VALUES (?);`, version); err != nil {
-		tx.Rollback()
-		return nil, err
-	}
-	tx.Commit()
-	return &DB{ctx: ctx, db: db}, nil
-}
 
-func (db *DB) Close() error {
-	return db.db.Close()
+		for version < len(statements) {
+			if _, err = tx.ExecContext(db.ctx, statements[version]); err != nil {
+				return err
+			}
+			version++
+		}
+		_, err = tx.ExecContext(db.ctx, `DELETE FROM schema_version; INSERT INTO schema_version (version) VALUES (?);`, version)
+		return err
+	})
 }