Added a unique constraint to cache keys.

database/migrations/2016_06_15_075023_fix_cache_table.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * Pony.fm - A community for pony fan music.
+ * Copyright (C) 2016 Peter Deltchev
+ *
+ * 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/>.
+ */
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class FixCacheTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        // Wipe the cache table - it's in a corrupt state because
+        // it allowed duplicate keys to exist until now.
+        DB::table('cache')->delete();
+
+        Schema::table('cache', function (Blueprint $table) {
+            $table->unique('key');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('cache', function (Blueprint $table) {
+            $table->dropUnique('cache_key_unique');
+        });
+    }
+}