ceph/src/common/OpQueue.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef OP_QUEUE_H
  16 #define OP_QUEUE_H
  17
  18 #include "include/msgr.h"
  19
  20 #include <list>
  21 #include <functional>
  22
  23 namespace ceph {
  24   class Formatter;
  25 }
  26
  27 /**
  28  * Abstract class for all Op Queues
  29  *
  30  * In order to provide optimized code, be sure to declare all
  31  * virutal functions as final in the derived class.
  32  */
  33
  34 template <typename T, typename K>
  35 class OpQueue {
  36
  37   public:
  38     // How many Ops are in the queue
  39     virtual unsigned length() const = 0;
  40     // Ops of this class should be deleted immediately. If out isn't
  41     // nullptr then items should be added to the front in
  42     // front-to-back order. The typical strategy is to visit items in
  43     // the queue in *reverse* order and to use *push_front* to insert
  44     // them into out.
  45     virtual void remove_by_class(K k, std::list<T> *out) = 0;
  46     // Enqueue op in the back of the strict queue
  47     virtual void enqueue_strict(K cl, unsigned priority, T item) = 0;
  48     // Enqueue op in the front of the strict queue
  49     virtual void enqueue_strict_front(K cl, unsigned priority, T item) = 0;
  50     // Enqueue op in the back of the regular queue
  51     virtual void enqueue(K cl, unsigned priority, unsigned cost, T item) = 0;
  52     // Enqueue the op in the front of the regular queue
  53     virtual void enqueue_front(K cl, unsigned priority, unsigned cost, T item) = 0;
  54     // Returns if the queue is empty
  55     virtual bool empty() const = 0;
  56     // Return an op to be dispatch
  57     virtual T dequeue() = 0;
  58     // Formatted output of the queue
  59     virtual void dump(ceph::Formatter *f) const = 0;
  60     // Don't leak resources on destruction
  61     virtual ~OpQueue() {};
  62 };
  63
  64 #endif