2019-12-16 18:45:21 +00:00
|
|
|
package dqlite
|
|
|
|
|
|
|
|
import (
|
|
|
|
"fmt"
|
|
|
|
"os"
|
|
|
|
|
|
|
|
"github.com/canonical/go-dqlite/internal/bindings"
|
2020-04-23 20:34:44 +00:00
|
|
|
"github.com/canonical/go-dqlite/internal/protocol"
|
2019-12-16 18:45:21 +00:00
|
|
|
"github.com/pkg/errors"
|
|
|
|
)
|
|
|
|
|
|
|
|
// ConfigMultiThread sets the threading mode of SQLite to Multi-thread.
|
|
|
|
//
|
|
|
|
// By default go-dqlite configures SQLite to Single-thread mode, because the
|
|
|
|
// dqlite engine itself is single-threaded, and enabling Multi-thread or
|
|
|
|
// Serialized modes would incur in a performance penality.
|
|
|
|
//
|
|
|
|
// If your Go process also uses SQLite directly (e.g. using the
|
|
|
|
// github.com/mattn/go-sqlite3 bindings) you might need to switch to
|
|
|
|
// Multi-thread mode in order to be thread-safe.
|
|
|
|
//
|
|
|
|
// IMPORTANT: It's possible to successfully change SQLite's threading mode only
|
|
|
|
// if no SQLite APIs have been invoked yet (e.g. no database has been opened
|
|
|
|
// yet). Therefore you'll typically want to call ConfigMultiThread() very early
|
|
|
|
// in your process setup. Alternatively you can set the GO_DQLITE_MULTITHREAD
|
|
|
|
// environment variable to 1 at process startup, in order to prevent go-dqlite
|
|
|
|
// from setting Single-thread mode at all.
|
|
|
|
func ConfigMultiThread() error {
|
|
|
|
if err := bindings.ConfigMultiThread(); err != nil {
|
2020-04-23 20:34:44 +00:00
|
|
|
if err, ok := err.(protocol.Error); ok && err.Code == 21 /* SQLITE_MISUSE */ {
|
2019-12-16 18:45:21 +00:00
|
|
|
return fmt.Errorf("SQLite is already initialized")
|
|
|
|
}
|
|
|
|
return errors.Wrap(err, "unknown error")
|
|
|
|
}
|
|
|
|
return nil
|
|
|
|
}
|
|
|
|
|
|
|
|
func init() {
|
|
|
|
// Don't enable single thread mode by default if GO_DQLITE_MULTITHREAD
|
|
|
|
// is set.
|
|
|
|
if os.Getenv("GO_DQLITE_MULTITHREAD") == "1" {
|
|
|
|
return
|
|
|
|
}
|
|
|
|
err := bindings.ConfigSingleThread()
|
|
|
|
if err != nil {
|
|
|
|
panic(errors.Wrap(err, "set single thread mode"))
|
|
|
|
}
|
|
|
|
}
|