1 files changed, 187 insertions, 0 deletions
diff --git a/core/includes/database/mysql/database.inc b/core/includes/database/mysql/database.inc
new file mode 100644
index 000000000000..7d5d85998dbd
--- /dev/null
+++ b/core/includes/database/mysql/database.inc
@@ -0,0 +1,187 @@
+<?php
+
+/**
+ * @file
+ * Database interface code for MySQL database servers.
+ */
+
+/**
+ * @ingroup database
+ * @{
+ */
+
+class DatabaseConnection_mysql extends DatabaseConnection {
+
+  /**
+   * Flag to indicate if we have registered the nextID cleanup function.
+   *
+   * @var boolean
+   */
+  protected $shutdownRegistered = FALSE;
+
+  public function __construct(array $connection_options = array()) {
+    // This driver defaults to transaction support, except if explicitly passed FALSE.
+    $this->transactionSupport = !isset($connection_options['transactions']) || ($connection_options['transactions'] !== FALSE);
+
+    // MySQL never supports transactional DDL.
+    $this->transactionalDDLSupport = FALSE;
+
+    $this->connectionOptions = $connection_options;
+
+    // The DSN should use either a socket or a host/port.
+    if (isset($connection_options['unix_socket'])) {
+      $dsn = 'mysql:unix_socket=' . $connection_options['unix_socket'];
+    }
+    else {
+      // Default to TCP connection on port 3306.
+      $dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . (empty($connection_options['port']) ? 3306 : $connection_options['port']);
+    }
+    $dsn .= ';dbname=' . $connection_options['database'];
+    parent::__construct($dsn, $connection_options['username'], $connection_options['password'], array(
+      // So we don't have to mess around with cursors and unbuffered queries by default.
+      PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
+      // Because MySQL's prepared statements skip the query cache, because it's dumb.
+      PDO::ATTR_EMULATE_PREPARES => TRUE,
+      // Force column names to lower case.
+      PDO::ATTR_CASE => PDO::CASE_LOWER,
+    ));
+
+    // Force MySQL to use the UTF-8 character set. Also set the collation, if a
+    // certain one has been set; otherwise, MySQL defaults to 'utf8_general_ci'
+    // for UTF-8.
+    if (!empty($connection_options['collation'])) {
+      $this->exec('SET NAMES utf8 COLLATE ' . $connection_options['collation']);
+    }
+    else {
+      $this->exec('SET NAMES utf8');
+    }
+
+    // Force MySQL's behavior to conform more closely to SQL standards.
+    // This allows Drupal to run almost seamlessly on many different
+    // kinds of database systems. These settings force MySQL to behave
+    // the same as postgresql, or sqlite in regards to syntax interpretation
+    // and invalid data handling. See http://drupal.org/node/344575 for
+    // further discussion. Also, as MySQL 5.5 changed the meaning of
+    // TRADITIONAL we need to spell out the modes one by one.
+    $this->exec("SET sql_mode='ANSI,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER'");
+  }
+
+  public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
+    return $this->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);
+  }
+
+  public function queryTemporary($query, array $args = array(), array $options = array()) {
+    $tablename = $this->generateTemporaryTableName();
+    $this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY SELECT', $query), $args, $options);
+    return $tablename;
+  }
+
+  public function driver() {
+    return 'mysql';
+  }
+
+  public function databaseType() {
+    return 'mysql';
+  }
+
+  public function mapConditionOperator($operator) {
+    // We don't want to override any of the defaults.
+    return NULL;
+  }
+
+  public function nextId($existing_id = 0) {
+    $new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
+    // This should only happen after an import or similar event.
+    if ($existing_id >= $new_id) {
+      // If we INSERT a value manually into the sequences table, on the next
+      // INSERT, MySQL will generate a larger value. However, there is no way
+      // of knowing whether this value already exists in the table. MySQL
+      // provides an INSERT IGNORE which would work, but that can mask problems
+      // other than duplicate keys. Instead, we use INSERT ... ON DUPLICATE KEY
+      // UPDATE in such a way that the UPDATE does not do anything. This way,
+      // duplicate keys do not generate errors but everything else does.
+      $this->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(':value' => $existing_id));
+      $new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
+    }
+    if (!$this->shutdownRegistered) {
+      // Use register_shutdown_function() here to keep the database system
+      // independent of Drupal.
+      register_shutdown_function(array($this, 'nextIdDelete'));
+      $shutdownRegistered = TRUE;
+    }
+    return $new_id;
+  }
+
+  public function nextIdDelete() {
+    // While we want to clean up the table to keep it up from occupying too
+    // much storage and memory, we must keep the highest value in the table
+    // because InnoDB  uses an in-memory auto-increment counter as long as the
+    // server runs. When the server is stopped and restarted, InnoDB
+    // reinitializes the counter for each table for the first INSERT to the
+    // table based solely on values from the table so deleting all values would
+    // be a problem in this case. Also, TRUNCATE resets the auto increment
+    // counter.
+    try {
+      $max_id = $this->query('SELECT MAX(value) FROM {sequences}')->fetchField();
+      // We know we are using MySQL here, no need for the slower db_delete().
+      $this->query('DELETE FROM {sequences} WHERE value < :value', array(':value' => $max_id));
+    }
+    // During testing, this function is called from shutdown with the
+    // simpletest prefix stored in $this->connection, and those tables are gone
+    // by the time shutdown is called so we need to ignore the database
+    // errors. There is no problem with completely ignoring errors here: if
+    // these queries fail, the sequence will work just fine, just use a bit
+    // more database storage and memory.
+    catch (PDOException $e) {
+    }
+  }
+
+  /**
+   * Overridden to work around issues to MySQL not supporting transactional DDL.
+   */
+  protected function popCommittableTransactions() {
+    // Commit all the committable layers.
+    foreach (array_reverse($this->transactionLayers) as $name => $active) {
+      // Stop once we found an active transaction.
+      if ($active) {
+        break;
+      }
+
+      // If there are no more layers left then we should commit.
+      unset($this->transactionLayers[$name]);
+      if (empty($this->transactionLayers)) {
+        if (!PDO::commit()) {
+          throw new DatabaseTransactionCommitFailedException();
+        }
+      }
+      else {
+        // Attempt to release this savepoint in the standard way.
+        try {
+          $this->query('RELEASE SAVEPOINT ' . $name);
+        }
+        catch (PDOException $e) {
+          // However, in MySQL (InnoDB), savepoints are automatically committed
+          // when tables are altered or created (DDL transactions are not
+          // supported). This can cause exceptions due to trying to release
+          // savepoints which no longer exist.
+          //
+          // To avoid exceptions when no actual error has occurred, we silently
+          // succeed for MySQL error code 1305 ("SAVEPOINT does not exist").
+          if ($e->errorInfo[1] == '1305') {
+            // If one SAVEPOINT was released automatically, then all were.
+            // Therefore, we keep just the topmost transaction.
+            $this->transactionLayers = array('drupal_transaction' => 'drupal_transaction');
+          }
+          else {
+            throw $e;
+          }
+        }
+      }
+    }
+  }
+}
+
+
+/**
+ * @} End of "ingroup database".
+ */