ceph/src/common/WeightedPriorityQueue.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 WP_QUEUE_H
  16 #define WP_QUEUE_H
  17
  18 #include "OpQueue.h"
  19
  20 #include <boost/intrusive/list.hpp>
  21 #include <boost/intrusive/rbtree.hpp>
  22 #include <boost/intrusive/avl_set.hpp>
  23
  24 namespace bi = boost::intrusive;
  25
  26 template <typename T, typename S>
  27 class MapKey
  28 {
  29   public:
  30   bool operator()(const S i, const T &k) const
  31   {
  32     return i < k.key;
  33   }
  34   bool operator()(const T &k, const S i) const
  35   {
  36     return k.key < i;
  37   }
  38 };
  39
  40 template <typename T>
  41 class DelItem
  42 {
  43   public:
  44   void operator()(T* delete_this)
  45     { delete delete_this; }
  46 };
  47
  48 template <typename T, typename K>
  49 class WeightedPriorityQueue :  public OpQueue <T, K>
  50 {
  51   private:
  52     class ListPair : public bi::list_base_hook<>
  53     {
  54       public:
  55         unsigned cost;
  56         T item;
  57         ListPair(unsigned c, T& i) :
  58           cost(c),
  59           item(i)
  60           {}
  61     };
  62     class Klass : public bi::set_base_hook<>
  63     {
  64       typedef bi::list<ListPair> ListPairs;
  65       typedef typename ListPairs::iterator Lit;
  66       public:
  67         K key;          // klass
  68         ListPairs lp;
  69         Klass(K& k) :
  70           key(k)
  71           {}
  72       friend bool operator< (const Klass &a, const Klass &b)
  73         { return a.key < b.key; }
  74       friend bool operator> (const Klass &a, const Klass &b)
  75         { return a.key > b.key; }
  76       friend bool operator== (const Klass &a, const Klass &b)
  77         { return a.key == b.key; }
  78       void insert(unsigned cost, T& item, bool front) {
  79         if (front) {
  80           lp.push_front(*new ListPair(cost, item));
  81         } else {
  82           lp.push_back(*new ListPair(cost, item));
  83         }
  84       }
  85       //Get the cost of the next item to dequeue
  86       unsigned get_cost() const {
  87         assert(!empty());
  88         return lp.begin()->cost;
  89       }
  90       T pop() {
  91         assert(!lp.empty());
  92         T ret = lp.begin()->item;
  93         lp.erase_and_dispose(lp.begin(), DelItem<ListPair>());
  94         return ret;
  95       }
  96       bool empty() const {
  97         return lp.empty();
  98       }
  99       unsigned get_size() const {
 100         return lp.size();
 101       }
 102       unsigned filter_class(std::list<T>* out) {
 103         unsigned count = 0;
 104         for (Lit i = --lp.end();; --i) {
 105           if (out) {
 106             out->push_front(i->item);
 107           }
 108           i = lp.erase_and_dispose(i, DelItem<ListPair>());
 109           ++count;
 110           if (i == lp.begin()) {
 111             break;
 112           }
 113         }
 114         return count;
 115       }
 116     };
 117     class SubQueue : public bi::set_base_hook<>
 118     {
 119       typedef bi::rbtree<Klass> Klasses;
 120       typedef typename Klasses::iterator Kit;
 121       void check_end() {
 122         if (next == klasses.end()) {
 123           next = klasses.begin();
 124         }
 125       }
 126       public:
 127         unsigned key;   // priority
 128         Klasses klasses;
 129         Kit next;
 130         SubQueue(unsigned& p) :
 131           key(p),
 132           next(klasses.begin())
 133           {}
 134       friend bool operator< (const SubQueue &a, const SubQueue &b)
 135         { return a.key < b.key; }
 136       friend bool operator> (const SubQueue &a, const SubQueue &b)
 137         { return a.key > b.key; }
 138       friend bool operator== (const SubQueue &a, const SubQueue &b)
 139         { return a.key == b.key; }
 140       bool empty() const {
 141         return klasses.empty();
 142       }
 143       void insert(K cl, unsigned cost, T& item, bool front = false) {
 144         typename Klasses::insert_commit_data insert_data;
 145         std::pair<Kit, bool> ret =
 146           klasses.insert_unique_check(cl, MapKey<Klass, K>(), insert_data);
 147         if (ret.second) {
 148           ret.first = klasses.insert_unique_commit(*new Klass(cl), insert_data);
 149           check_end();
 150         }
 151         ret.first->insert(cost, item, front);
 152       }
 153       unsigned get_cost() const {
 154         assert(!empty());
 155         return next->get_cost();
 156       }
 157       T pop() {
 158         T ret = next->pop();
 159         if (next->empty()) {
 160           next = klasses.erase_and_dispose(next, DelItem<Klass>());
 161         } else {
 162           ++next;
 163         }
 164         check_end();
 165         return ret;
 166       }
 167       unsigned filter_class(K& cl, std::list<T>* out) {
 168         unsigned count = 0;
 169         Kit i = klasses.find(cl, MapKey<Klass, K>());
 170         if (i != klasses.end()) {
 171           count = i->filter_class(out);
 172           Kit tmp = klasses.erase_and_dispose(i, DelItem<Klass>());
 173           if (next == i) {
 174             next = tmp;
 175           }
 176           check_end();
 177         }
 178         return count;
 179       }
 180       void dump(ceph::Formatter *f) const {
 181         f->dump_int("num_keys", next->get_size());
 182         if (!empty()) {
 183           f->dump_int("first_item_cost", next->get_cost());
 184         }
 185       }
 186     };
 187     class Queue {
 188       typedef bi::rbtree<SubQueue> SubQueues;
 189       typedef typename SubQueues::iterator Sit;
 190       SubQueues queues;
 191       unsigned total_prio;
 192       unsigned max_cost;
 193       public:
 194         unsigned size;
 195         Queue() :
 196           total_prio(0),
 197           max_cost(0),
 198           size(0)
 199           {}
 200         bool empty() const {
 201           return !size;
 202         }
 203         void insert(unsigned p, K cl, unsigned cost, T& item, bool front = false) {
 204           typename SubQueues::insert_commit_data insert_data;
 205           std::pair<typename SubQueues::iterator, bool> ret =
 206             queues.insert_unique_check(p, MapKey<SubQueue, unsigned>(), insert_data);
 207           if (ret.second) {
 208             ret.first = queues.insert_unique_commit(*new SubQueue(p), insert_data);
 209             total_prio += p;
 210           }
 211           ret.first->insert(cl, cost, item, front);
 212           if (cost > max_cost) {
 213             max_cost = cost;
 214           }
 215           ++size;
 216         }
 217         T pop(bool strict = false) {
 218           --size;
 219           Sit i = --queues.end();
 220           if (strict) {
 221             T ret = i->pop();
 222             if (i->empty()) {
 223               queues.erase_and_dispose(i, DelItem<SubQueue>());
 224             }
 225             return ret;
 226           }
 227           if (queues.size() > 1) {
 228             while (true) {
 229               // Pick a new priority out of the total priority.
 230               unsigned prio = rand() % total_prio + 1;
 231               unsigned tp = total_prio - i->key;
 232               // Find the priority coresponding to the picked number.
 233               // Subtract high priorities to low priorities until the picked number
 234               // is more than the total and try to dequeue that priority.
 235               // Reverse the direction from previous implementation because there is a higher
 236               // chance of dequeuing a high priority op so spend less time spinning.
 237               while (prio <= tp) {
 238                 --i;
 239                 tp -= i->key;
 240               }
 241               // Flip a coin to see if this priority gets to run based on cost.
 242               // The next op's cost is multiplied by .9 and subtracted from the
 243               // max cost seen. Ops with lower costs will have a larger value
 244               // and allow them to be selected easier than ops with high costs.
 245               if (max_cost == 0 || rand() % max_cost <=
 246                   (max_cost - ((i->get_cost() * 9) / 10))) {
 247                 break;
 248               }
 249               i = --queues.end();
 250             }
 251           }
 252           T ret = i->pop();
 253           if (i->empty()) {
 254             total_prio -= i->key;
 255             queues.erase_and_dispose(i, DelItem<SubQueue>());
 256           }
 257           return ret;
 258         }
 259         void filter_class(K& cl, std::list<T>* out) {
 260           for (Sit i = queues.begin(); i != queues.end();) {
 261             size -= i->filter_class(cl, out);
 262             if (i->empty()) {
 263               total_prio -= i->key;
 264               i = queues.erase_and_dispose(i, DelItem<SubQueue>());
 265             } else {
 266               ++i;
 267             }
 268           }
 269         }
 270         void dump(ceph::Formatter *f) const {
 271           for (typename SubQueues::const_iterator i = queues.begin();
 272                 i != queues.end(); ++i) {
 273             f->dump_int("total_priority", total_prio);
 274             f->dump_int("max_cost", max_cost);
 275             f->open_object_section("subqueue");
 276             f->dump_int("priority", i->key);
 277             i->dump(f);
 278             f->close_section();
 279           }
 280         }
 281     };
 282
 283     Queue strict;
 284     Queue normal;
 285   public:
 286     WeightedPriorityQueue(unsigned max_per, unsigned min_c) :
 287       strict(),
 288       normal()
 289       {
 290         std::srand(time(0));
 291       }
 292     unsigned length() const final {
 293       return strict.size + normal.size;
 294     }
 295     void remove_by_class(K cl, std::list<T>* removed = 0) final {
 296       strict.filter_class(cl, removed);
 297       normal.filter_class(cl, removed);
 298     }
 299     bool empty() const final {
 300       return !(strict.size + normal.size);
 301     }
 302     void enqueue_strict(K cl, unsigned p, T item) final {
 303       strict.insert(p, cl, 0, item);
 304     }
 305     void enqueue_strict_front(K cl, unsigned p, T item) final {
 306       strict.insert(p, cl, 0, item, true);
 307     }
 308     void enqueue(K cl, unsigned p, unsigned cost, T item) final {
 309       normal.insert(p, cl, cost, item);
 310     }
 311     void enqueue_front(K cl, unsigned p, unsigned cost, T item) final {
 312       normal.insert(p, cl, cost, item, true);
 313     }
 314     T dequeue() override {
 315       assert(strict.size + normal.size > 0);
 316       if (!strict.empty()) {
 317         return strict.pop(true);
 318       }
 319       return normal.pop();
 320     }
 321     void dump(ceph::Formatter *f) const override {
 322       f->open_array_section("high_queues");
 323       strict.dump(f);
 324       f->close_section();
 325       f->open_array_section("queues");
 326       normal.dump(f);
 327       f->close_section();
 328     }
 329 };
 330
 331 #endif