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diff --git a/src/common/OpQueue.h b/src/common/OpQueue.h
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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#ifndef OP_QUEUE_H
+#define OP_QUEUE_H
+
+#include "include/msgr.h"
+
+#include <list>
+#include <functional>
+
+namespace ceph {
+  class Formatter;
+}
+
+/**
+ * Abstract class for all Op Queues
+ *
+ * In order to provide optimized code, be sure to declare all
+ * virtual functions as final in the derived class.
+ */
+
+template <typename T, typename K>
+class OpQueue {
+public:
+  // Ops of this class should be deleted immediately. If out isn't
+  // nullptr then items should be added to the front in
+  // front-to-back order. The typical strategy is to visit items in
+  // the queue in *reverse* order and to use *push_front* to insert
+  // them into out.
+  virtual void remove_by_class(K k, std::list<T> *out) = 0;
+
+  // Enqueue op in the back of the strict queue
+  virtual void enqueue_strict(K cl, unsigned priority, T &&item) = 0;
+
+  // Enqueue op in the front of the strict queue
+  virtual void enqueue_strict_front(K cl, unsigned priority, T &&item) = 0;
+
+  // Enqueue op in the back of the regular queue
+  virtual void enqueue(K cl, unsigned priority, unsigned cost, T &&item) = 0;
+
+  // Enqueue the op in the front of the regular queue
+  virtual void enqueue_front(
+    K cl, unsigned priority, unsigned cost, T &&item) = 0;
+
+  // Returns if the queue is empty
+  virtual bool empty() const = 0;
+
+  // Return an op to be dispatch
+  virtual T dequeue() = 0;
+
+  // Formatted output of the queue
+  virtual void dump(ceph::Formatter *f) const = 0;
+
+  // Human readable brief description of queue and relevant parameters
+  virtual void print(std::ostream &f) const = 0;
+
+  // Don't leak resources on destruction
+  virtual ~OpQueue() {};
+};
+
+#endif