Starting to encapsulate some of the schema_version checksum / updater logic

[quix0rs-gnu-social.git] / lib / schemaupdater.php

diff --git a/lib/schemaupdater.php b/lib/schemaupdater.php
new file mode 100644 (file)
index 0000000..b872b0d
--- /dev/null
+++ b/lib/schemaupdater.php
@@ -0,0 +1,117 @@
+<?php
+
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * Database schema utilities
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Database
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+
+class SchemaUpdater
+{
+    public function __construct($schema)
+    {
+        $this->schema = $schema;
+        $this->conn = $conn;
+        $this->checksums = $this->getChecksums();
+    }
+
+    /**
+     * @param array $tableDefs
+     * @fixme handle tables that belong on different database servers...?
+     */
+    public function checkTables(array $tableDefs)
+    {
+        $checksums = $this->checksums;
+        foreach ($tableDefs as $table => $def) {
+            $checksum = $this->tableChecksum($def);
+            if (empty($checksums[$table])) {
+                common_log(LOG_DEBUG, "No previous schema_version for $table: updating to $checksum");
+            } else if ($checksums[$table] == $checksum) {
+                common_log(LOG_DEBUG, "Last schema_version for $table up to date: $checksum");
+                continue;
+            } else {
+                common_log(LOG_DEBUG, "Last schema_version for $table is {$checksums[$table]}: updating to $checksum");
+            }
+            $this->conn->query('BEGIN');
+            $this->schema->ensureTable($table, $def);
+            $this->saveChecksum($table, $checksum);
+            $this->conn->commit();
+        }
+    }
+
+    /**
+     * Calculate a checksum for this table definition array.
+     *
+     * @param array $def
+     * @return string
+     */
+    public function checksum(array $def)
+    {
+        $flat = serialize($def);
+        return sha1($flat);
+    }
+
+    /**
+     * Pull all known table checksums into an array for easy lookup.
+     *
+     * @return array: associative array of table names to checksum strings
+     */
+    protected function getChecksums()
+    {
+        $checksums = array();
+
+        $sv = new Schema_version();
+        $sv->find();
+        while ($sv->fetch()) {
+            $checksums[$sv->table_name] = $sv->checksum;
+        }
+
+        return $checksums;
+    }
+
+    /**
+     * Save or update current available checksums.
+     *
+     * @param string $table
+     * @param string $checksum
+     */
+    protected function saveChecksum($table, $checksum)
+    {
+        $sv = new Schema_version();
+        $sv->table_name = $table;
+        $sv->checksum = $checksum;
+        $sv->modified = common_sql_now();
+        if (isset($this->checksums[$table])) {
+            $sv->update();
+        } else {
+            $sv->insert();
+        }
+        $this->checksums[$table] = $checksum;
+    }
+}