From f14a7566f95301542aab53506f6b304e89865f5d Mon Sep 17 00:00:00 2001
From: Gert-Jan Timmer <gjr.timmer@gmail.com>
Date: Tue, 29 May 2018 13:19:40 +0200
Subject: [PATCH] ADD: PRAGMA locking_mode

---
 README.md  |  1 +
 sqlite3.go | 29 ++++++++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 19190e1..2e1312f 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,7 @@ Boolean values can be one of:
 | Foreign Keys | `_foreign_keys` \| `_fk` | `boolean` | For more information see [PRAGMA foreign_keys](https://www.sqlite.org/pragma.html#pragma_foreign_keys) |
 | Ignore CHECK Constraints | `_ignore_check_constraints` | `boolean` | For more information see [PRAGMA ignore_check_constraints](https://www.sqlite.org/pragma.html#pragma_ignore_check_constraints) |
 | Journal Mode | `_journal` | <ul><li>DELETE</li><li>TRUNCATE</li><li>PERSIST</li><li>MEMORY</li><li>WAL</li><li>OFF</li></ul> | For more information see [PRAGMA journal_mode](https://www.sqlite.org/pragma.html#pragma_journal_mode) |
+| Locking Mode | `_locking` | <ul><li>NORMAL</li><li>EXCLUSIVE</li></ul> | For more information see [PRAGMA locking_mode](https://www.sqlite.org/pragma.html#pragma_locking_mode) |
 | Mode | `mode` | <ul><li>ro</li><li>rw</li><li>rwc</li><li>memory</li></ul> | Access Mode of the database. For more information see [SQLite Open](https://www.sqlite.org/c3ref/open.html) |
 | Mutex Locking | `_mutex` | <ul><li>no</li><li>full</li></ul> | Specify mutex mode. |
 | Recursive Triggers | `_recursive_triggers` \| `_rt` | `boolean` | For more information see [PRAGMA recursive_triggers](https://www.sqlite.org/pragma.html#pragma_recursive_triggers) |
diff --git a/sqlite3.go b/sqlite3.go
index 3855882..b0a330d 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -842,6 +842,11 @@ func errorString(err Error) string {
 //     Set journal mode for the databases associated with the current connection.
 //     https://www.sqlite.org/pragma.html#pragma_journal_mode
 //
+//   _locking=X
+//     Sets the database connection locking-mode.
+//     The locking-mode is either NORMAL or EXCLUSIVE.
+//     https://www.sqlite.org/pragma.html#pragma_locking_mode
+//
 //   _recursive_triggers=Boolean | _rt=Boolean
 //     Enable or disable recursive triggers.
 //
@@ -866,9 +871,10 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	busyTimeout := 5000
 	caseSensitiveLike := -1
 	deferForeignKeys := -1
+	foreignKeys := -1
 	ignoreCheckConstraints := -1
 	journalMode := "DELETE"
-	foreignKeys := -1
+	lockingMode := "NORMAL"
 	recursiveTriggers := -1
 
 	pos := strings.IndexRune(dsn, '?')
@@ -1040,6 +1046,19 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 			}
 		}
 
+		// Locking Mode (_locking)
+		//
+		// https://www.sqlite.org/pragma.html#pragma_locking_mode
+		//
+		if val := params.Get("_locking"); val != "" {
+			switch strings.ToUpper(val) {
+			case "NORMAL", "EXCLUSIVE":
+				lockingMode = strings.ToUpper(val)
+			default:
+				return nil, fmt.Errorf("Invalid _locking: %v, expecting value of 'NORMAL EXCLUSIVE", val)
+			}
+		}
+
 		// Recursive Triggers (_recursive_triggers)
 		//
 		// https://www.sqlite.org/pragma.html#pragma_recursive_triggers
@@ -1143,6 +1162,14 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		return nil, err
 	}
 
+	// Locking Mode
+	// Because the default is NORMAL and this is not changed in this package
+	// by using the compile time SQLITE_DEFAULT_LOCKING_MODE this PRAGMA can always be executed
+	if err := exec(fmt.Sprintf("PRAGMA locking_mode = %s;", lockingMode)); err != nil {
+		C.sqlite3_close_v2(db)
+		return nil, err
+	}
+
 	// Recursive Triggers
 	if recursiveTriggers > -1 {
 		if err := exec(fmt.Sprintf("PRAGMA recursive_triggers = %d;", recursiveTriggers)); err != nil {