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archived-php-src/ext/pdo_sqlite/php_pdo_sqlite.h
Samuel Štancl a09d919ce8 Implement GH-8967: Add PDO_SQLITE_ATTR_TRANSACTION_MODE (#19317)
This commit implements GH-8967.

SQLite supports multiple transaction modes. These include:
- DEFERRED (default) only acquires a lock when you start a read/write
- IMMEDIATE acquires a reserved lock
- EXCLUSIVE acquires an exclusive lock (stricter than immediate)

In WAL mode IMMEDIATE and EXCLUSIVE are identical.

One reason for wanting to specify a transaction mode is that SQLite
doesn't respect busy_timeout when a DEFERRED transaction tries to
upgrade a read lock to a write lock. Normally if you try to acquire a
lock and have busy_timeout configured, SQLite will wait for that period
until giving up and erroring out (SQLITE_BUSY). With DEFERRED, if you
have a transaction that first reads and there's a concurrent writer
while it's trying to upgrade to a write lock, you will immediately get
SQLITE_BUSY regardless of your busy_timeout.

Prior to this commit, the only available workarounds were:
- Using $pdo->exec("BEGIN IMMEDIATE TRANSACTION") instead of
  $pdo->beginTransaction()
- Doing a dummy write at the start of each transaction so you don't get
  stuck with a read lock

Both of those aren't very usable, especially in a framework context
where the user doesn't have complete control over how transactions are
started.

To address that, this commit adds four class constants to Pdo\Sqlite:
- ATTR_TRANSACTION_MODE -- a new attribute
- TRANSACTION_MODE_DEFERRED = 0
- TRANSACTION_MODE_IMMEDIATE = 1
- TRANSACTION_MODE_EXCLUSIVE = 2

These can be used as:
  $pdo->setAttribute(
    $pdo::ATTR_TRANSACTION_MODE,
    $pdo::TRANSACTION_MODE_IMMEDIATE
  );
2025-09-07 15:42:30 +02:00

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1.6 KiB
C

/*
+----------------------------------------------------------------------+
| Copyright (c) The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 3.01 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| https://www.php.net/license/3_01.txt |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Author: Wez Furlong <wez@php.net> |
+----------------------------------------------------------------------+
*/
#ifndef PHP_PDO_SQLITE_H
#define PHP_PDO_SQLITE_H
extern zend_module_entry pdo_sqlite_module_entry;
#define phpext_pdo_sqlite_ptr &pdo_sqlite_module_entry
#include "php_version.h"
#define PHP_PDO_SQLITE_VERSION PHP_VERSION
#ifdef ZTS
#include "TSRM.h"
#endif
enum pdo_sqlite_transaction_mode {
PDO_SQLITE_TRANSACTION_MODE_DEFERRED = 0,
PDO_SQLITE_TRANSACTION_MODE_IMMEDIATE = 1,
PDO_SQLITE_TRANSACTION_MODE_EXCLUSIVE = 2
};
PHP_MINIT_FUNCTION(pdo_sqlite);
PHP_MSHUTDOWN_FUNCTION(pdo_sqlite);
PHP_RINIT_FUNCTION(pdo_sqlite);
PHP_RSHUTDOWN_FUNCTION(pdo_sqlite);
PHP_MINFO_FUNCTION(pdo_sqlite);
#endif /* PHP_PDO_SQLITE_H */