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msd2/tracking/piwik/core/Sequence.php

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+<?php
+/**
+ * Piwik - free/libre analytics platform
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ *
+ */
+namespace Piwik;
+
+use Exception;
+use Piwik\Db\AdapterInterface;
+
+/**
+ * Used for generating auto increment ids.
+ *
+ * Example:
+ *
+ * $sequence = new Sequence('my_sequence_name');
+ * $id = $sequence->getNextId();
+ * $db->insert('anytable', array('id' => $id, '...' => '...'));
+ */
+class Sequence
+{
+    const TABLE_NAME = 'sequence';
+    /**
+     * @var string
+     */
+    private $name;
+
+    /**
+     * @var AdapterInterface
+     */
+    private $db;
+
+    /**
+     * @var string
+     */
+    private $table;
+
+    /**
+     * The name of the table or sequence you want to get an id for.
+     *
+     * @param string $name eg 'archive_numeric_2014_11'
+     * @param AdapterInterface $db You can optionally pass a DB adapter to make it work against another database.
+     * @param string|null $tablePrefix
+     */
+    public function __construct($name, $db = null, $tablePrefix = null)
+    {
+        $this->name = $name;
+        $this->db = $db ?: Db::get();
+        $this->table = $this->getTableName($tablePrefix);
+    }
+
+    /**
+     * Creates / initializes a new sequence.
+     *
+     * @param int $initialValue
+     * @return int The actually used value to initialize the table.
+     *
+     * @throws \Exception in case a sequence having this name already exists.
+     */
+    public function create($initialValue = 0)
+    {
+        $initialValue = (int) $initialValue;
+
+        $this->db->insert($this->table, array('name' => $this->name, 'value' => $initialValue));
+
+        return $initialValue;
+    }
+
+    /**
+     * Returns true if the sequence exist.
+     *
+     * @return bool
+     */
+    public function exists()
+    {
+        $query = $this->db->query('SELECT * FROM ' . $this->table . ' WHERE name = ?', $this->name);
+
+        return $query->rowCount() > 0;
+    }
+
+    /**
+     * Get / allocate / reserve a new id for the current sequence. Important: Getting the next id will fail in case
+     * no such sequence exists. Make sure to create one if needed, see {@link create()}.
+     *
+     * @return int
+     * @throws Exception
+     */
+    public function getNextId()
+    {
+        $sql   = 'UPDATE ' . $this->table . ' SET value = LAST_INSERT_ID(value + 1) WHERE name = ?';
+
+        $result   = $this->db->query($sql, array($this->name));
+        $rowCount = $result->rowCount();
+
+        if (1 !== $rowCount) {
+            throw new Exception("Sequence '" . $this->name . "' not found.");
+        }
+
+        $createdId = $this->db->lastInsertId();
+
+        return (int) $createdId;
+    }
+
+    /**
+     * Returns the current max id.
+     * @return int
+     * @internal
+     */
+    public function getCurrentId()
+    {
+        $sql   = 'SELECT value FROM ' . $this->table . ' WHERE name = ?';
+
+        $id = $this->db->fetchOne($sql, array($this->name));
+
+        if (!empty($id) || '0' === $id || 0 === $id) {
+            return (int) $id;
+        }
+    }
+
+    private function getTableName($prefix)
+    {
+        return ($prefix !== null) ? $prefix . self::TABLE_NAME : Common::prefixTable(self::TABLE_NAME);
+    }
+}