Files
2026-09-22 10:31:53 +01:00

107 lines
3.1 KiB
Go

package db
import (
"database/sql"
"fmt"
"os"
"path/filepath"
"time"
_ "github.com/mattn/go-sqlite3"
)
const (
defaultBusyTimeout = 5 * time.Second
// defaultSQLiteReaderConns is the number of concurrent read connections.
// SQLite WAL mode allows many readers alongside a single writer; 4 is a
// reasonable default for a desktop/server workload.
defaultSQLiteReaderConns = 4
)
// OpenSQLite opens a SQLite database configured for writes (single connection).
func OpenSQLite(dbPath string) (*sql.DB, error) {
normalizedPath := normalizeSQLitePath(dbPath)
if err := ensureSQLiteDir(normalizedPath); err != nil {
return nil, fmt.Errorf("failed to prepare database path: %w", err)
}
if err := ensureSQLiteFile(normalizedPath); err != nil {
return nil, fmt.Errorf("failed to create database file: %w", err)
}
// Writer DSN settings:
// - foreign_keys=on: enforce FK constraints consistently.
// - busy_timeout: wait briefly on locks to reduce transient "database is locked".
// - journal_mode=WAL: better read concurrency with a single writer.
// - synchronous=NORMAL: reasonable durability/perf tradeoff for app workloads.
// - cache=shared: allow multiple connections to share a page cache.
dsn := fmt.Sprintf(
"file:%s?_foreign_keys=on&_mode=rwc&_busy_timeout=%d&_journal_mode=WAL&_synchronous=NORMAL&_cache=shared",
normalizedPath,
int(defaultBusyTimeout/time.Millisecond),
)
db, err := sql.Open("sqlite3", dsn)
if err != nil {
return nil, fmt.Errorf("failed to open database: %w", err)
}
// Single writer connection: serializes writes and avoids SQLITE_BUSY.
db.SetMaxOpenConns(1)
db.SetMaxIdleConns(1)
return db, nil
}
// OpenSQLiteReader opens a read-only SQLite connection pool with multiple
// concurrent connections. Combined with WAL mode, this allows readers to
// proceed without blocking on (or being blocked by) writes.
func OpenSQLiteReader(dbPath string) (*sql.DB, error) {
normalizedPath := normalizeSQLitePath(dbPath)
// Reader DSN: read-only mode and FK enforcement.
// Do not enable SQLite shared-cache mode: an active reader in that cache
// can make a later reader observe its stale snapshot after a writer commits.
// journal_mode and synchronous are database-level (set by the writer).
dsn := fmt.Sprintf(
"file:%s?_foreign_keys=on&mode=ro&_busy_timeout=%d",
normalizedPath,
int(defaultBusyTimeout/time.Millisecond),
)
db, err := sql.Open("sqlite3", dsn)
if err != nil {
return nil, fmt.Errorf("failed to open read-only database: %w", err)
}
db.SetMaxOpenConns(defaultSQLiteReaderConns)
db.SetMaxIdleConns(defaultSQLiteReaderConns)
return db, nil
}
func ensureSQLiteDir(dbPath string) error {
dir := filepath.Dir(dbPath)
if dir == "." || dir == "" {
return nil
}
return os.MkdirAll(dir, 0o755)
}
func ensureSQLiteFile(dbPath string) error {
file, err := os.OpenFile(dbPath, os.O_RDWR|os.O_CREATE, 0o644)
if err != nil {
return err
}
return file.Close()
}
func normalizeSQLitePath(dbPath string) string {
if dbPath == "" {
return dbPath
}
abs, err := filepath.Abs(dbPath)
if err != nil {
return dbPath
}
return abs
}