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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 PRIORITY_QUEUE_H | |
16 | #define PRIORITY_QUEUE_H | |
17 | ||
11fdf7f2 TL |
18 | #include "include/ceph_assert.h" |
19 | ||
7c673cae FG |
20 | #include "common/Formatter.h" |
21 | #include "common/OpQueue.h" | |
22 | ||
7c673cae FG |
23 | /** |
24 | * Manages queue for normal and strict priority items | |
25 | * | |
26 | * On dequeue, the queue will select the lowest priority queue | |
27 | * such that the q has bucket > cost of front queue item. | |
28 | * | |
29 | * If there is no such queue, we choose the next queue item for | |
30 | * the highest priority queue. | |
31 | * | |
32 | * Before returning a dequeued item, we place into each bucket | |
33 | * cost * (priority/total_priority) tokens. | |
34 | * | |
35 | * enqueue_strict and enqueue_strict_front queue items into queues | |
36 | * which are serviced in strict priority order before items queued | |
37 | * with enqueue and enqueue_front | |
38 | * | |
39 | * Within a priority class, we schedule round robin based on the class | |
40 | * of type K used to enqueue items. e.g. you could use entity_inst_t | |
41 | * to provide fairness for different clients. | |
42 | */ | |
43 | template <typename T, typename K> | |
44 | class PrioritizedQueue : public OpQueue <T, K> { | |
45 | int64_t total_priority; | |
46 | int64_t max_tokens_per_subqueue; | |
47 | int64_t min_cost; | |
48 | ||
49 | typedef std::list<std::pair<unsigned, T> > ListPairs; | |
7c673cae FG |
50 | |
51 | struct SubQueue { | |
52 | private: | |
53 | typedef std::map<K, ListPairs> Classes; | |
54 | Classes q; | |
55 | unsigned tokens, max_tokens; | |
56 | int64_t size; | |
57 | typename Classes::iterator cur; | |
58 | public: | |
59 | SubQueue(const SubQueue &other) | |
60 | : q(other.q), | |
61 | tokens(other.tokens), | |
62 | max_tokens(other.max_tokens), | |
63 | size(other.size), | |
64 | cur(q.begin()) {} | |
65 | SubQueue() | |
66 | : tokens(0), | |
67 | max_tokens(0), | |
68 | size(0), cur(q.begin()) {} | |
69 | void set_max_tokens(unsigned mt) { | |
70 | max_tokens = mt; | |
71 | } | |
72 | unsigned get_max_tokens() const { | |
73 | return max_tokens; | |
74 | } | |
75 | unsigned num_tokens() const { | |
76 | return tokens; | |
77 | } | |
78 | void put_tokens(unsigned t) { | |
79 | tokens += t; | |
80 | if (tokens > max_tokens) { | |
81 | tokens = max_tokens; | |
82 | } | |
83 | } | |
84 | void take_tokens(unsigned t) { | |
85 | if (tokens > t) { | |
86 | tokens -= t; | |
87 | } else { | |
88 | tokens = 0; | |
89 | } | |
90 | } | |
11fdf7f2 TL |
91 | void enqueue(K cl, unsigned cost, T &&item) { |
92 | q[cl].push_back(std::make_pair(cost, std::move(item))); | |
7c673cae FG |
93 | if (cur == q.end()) |
94 | cur = q.begin(); | |
95 | size++; | |
96 | } | |
11fdf7f2 TL |
97 | void enqueue_front(K cl, unsigned cost, T &&item) { |
98 | q[cl].push_front(std::make_pair(cost, std::move(item))); | |
7c673cae FG |
99 | if (cur == q.end()) |
100 | cur = q.begin(); | |
101 | size++; | |
102 | } | |
11fdf7f2 TL |
103 | std::pair<unsigned, T> &front() const { |
104 | ceph_assert(!(q.empty())); | |
105 | ceph_assert(cur != q.end()); | |
7c673cae FG |
106 | return cur->second.front(); |
107 | } | |
11fdf7f2 TL |
108 | T pop_front() { |
109 | ceph_assert(!(q.empty())); | |
110 | ceph_assert(cur != q.end()); | |
111 | T ret = std::move(cur->second.front().second); | |
7c673cae FG |
112 | cur->second.pop_front(); |
113 | if (cur->second.empty()) { | |
114 | q.erase(cur++); | |
115 | } else { | |
116 | ++cur; | |
117 | } | |
118 | if (cur == q.end()) { | |
119 | cur = q.begin(); | |
120 | } | |
121 | size--; | |
11fdf7f2 | 122 | return ret; |
7c673cae FG |
123 | } |
124 | unsigned length() const { | |
11fdf7f2 | 125 | ceph_assert(size >= 0); |
7c673cae FG |
126 | return (unsigned)size; |
127 | } | |
128 | bool empty() const { | |
129 | return q.empty(); | |
130 | } | |
7c673cae FG |
131 | void remove_by_class(K k, std::list<T> *out) { |
132 | typename Classes::iterator i = q.find(k); | |
133 | if (i == q.end()) { | |
134 | return; | |
135 | } | |
136 | size -= i->second.size(); | |
137 | if (i == cur) { | |
138 | ++cur; | |
139 | } | |
140 | if (out) { | |
141 | for (typename ListPairs::reverse_iterator j = | |
142 | i->second.rbegin(); | |
143 | j != i->second.rend(); | |
144 | ++j) { | |
11fdf7f2 | 145 | out->push_front(std::move(j->second)); |
7c673cae FG |
146 | } |
147 | } | |
148 | q.erase(i); | |
149 | if (cur == q.end()) { | |
150 | cur = q.begin(); | |
151 | } | |
152 | } | |
153 | ||
154 | void dump(ceph::Formatter *f) const { | |
155 | f->dump_int("tokens", tokens); | |
156 | f->dump_int("max_tokens", max_tokens); | |
157 | f->dump_int("size", size); | |
158 | f->dump_int("num_keys", q.size()); | |
159 | if (!empty()) { | |
160 | f->dump_int("first_item_cost", front().first); | |
161 | } | |
162 | } | |
163 | }; | |
164 | ||
165 | typedef std::map<unsigned, SubQueue> SubQueues; | |
166 | SubQueues high_queue; | |
167 | SubQueues queue; | |
168 | ||
169 | SubQueue *create_queue(unsigned priority) { | |
170 | typename SubQueues::iterator p = queue.find(priority); | |
171 | if (p != queue.end()) { | |
172 | return &p->second; | |
173 | } | |
174 | total_priority += priority; | |
175 | SubQueue *sq = &queue[priority]; | |
176 | sq->set_max_tokens(max_tokens_per_subqueue); | |
177 | return sq; | |
178 | } | |
179 | ||
180 | void remove_queue(unsigned priority) { | |
11fdf7f2 | 181 | ceph_assert(queue.count(priority)); |
7c673cae FG |
182 | queue.erase(priority); |
183 | total_priority -= priority; | |
11fdf7f2 | 184 | ceph_assert(total_priority >= 0); |
7c673cae FG |
185 | } |
186 | ||
187 | void distribute_tokens(unsigned cost) { | |
188 | if (total_priority == 0) { | |
189 | return; | |
190 | } | |
191 | for (typename SubQueues::iterator i = queue.begin(); | |
192 | i != queue.end(); | |
193 | ++i) { | |
194 | i->second.put_tokens(((i->first * cost) / total_priority) + 1); | |
195 | } | |
196 | } | |
197 | ||
198 | public: | |
199 | PrioritizedQueue(unsigned max_per, unsigned min_c) | |
200 | : total_priority(0), | |
201 | max_tokens_per_subqueue(max_per), | |
202 | min_cost(min_c) | |
203 | {} | |
204 | ||
11fdf7f2 | 205 | unsigned length() const { |
7c673cae FG |
206 | unsigned total = 0; |
207 | for (typename SubQueues::const_iterator i = queue.begin(); | |
208 | i != queue.end(); | |
209 | ++i) { | |
11fdf7f2 | 210 | ceph_assert(i->second.length()); |
7c673cae FG |
211 | total += i->second.length(); |
212 | } | |
213 | for (typename SubQueues::const_iterator i = high_queue.begin(); | |
214 | i != high_queue.end(); | |
215 | ++i) { | |
11fdf7f2 | 216 | ceph_assert(i->second.length()); |
7c673cae FG |
217 | total += i->second.length(); |
218 | } | |
219 | return total; | |
220 | } | |
221 | ||
7c673cae FG |
222 | void remove_by_class(K k, std::list<T> *out = 0) final { |
223 | for (typename SubQueues::iterator i = queue.begin(); | |
224 | i != queue.end(); | |
225 | ) { | |
226 | i->second.remove_by_class(k, out); | |
227 | if (i->second.empty()) { | |
228 | unsigned priority = i->first; | |
229 | ++i; | |
230 | remove_queue(priority); | |
231 | } else { | |
232 | ++i; | |
233 | } | |
234 | } | |
235 | for (typename SubQueues::iterator i = high_queue.begin(); | |
236 | i != high_queue.end(); | |
237 | ) { | |
238 | i->second.remove_by_class(k, out); | |
239 | if (i->second.empty()) { | |
240 | high_queue.erase(i++); | |
241 | } else { | |
242 | ++i; | |
243 | } | |
244 | } | |
245 | } | |
246 | ||
11fdf7f2 TL |
247 | void enqueue_strict(K cl, unsigned priority, T&& item) final { |
248 | high_queue[priority].enqueue(cl, 0, std::move(item)); | |
7c673cae FG |
249 | } |
250 | ||
11fdf7f2 TL |
251 | void enqueue_strict_front(K cl, unsigned priority, T&& item) final { |
252 | high_queue[priority].enqueue_front(cl, 0, std::move(item)); | |
7c673cae FG |
253 | } |
254 | ||
11fdf7f2 | 255 | void enqueue(K cl, unsigned priority, unsigned cost, T&& item) final { |
7c673cae FG |
256 | if (cost < min_cost) |
257 | cost = min_cost; | |
258 | if (cost > max_tokens_per_subqueue) | |
259 | cost = max_tokens_per_subqueue; | |
11fdf7f2 | 260 | create_queue(priority)->enqueue(cl, cost, std::move(item)); |
7c673cae FG |
261 | } |
262 | ||
11fdf7f2 | 263 | void enqueue_front(K cl, unsigned priority, unsigned cost, T&& item) final { |
7c673cae FG |
264 | if (cost < min_cost) |
265 | cost = min_cost; | |
266 | if (cost > max_tokens_per_subqueue) | |
267 | cost = max_tokens_per_subqueue; | |
11fdf7f2 | 268 | create_queue(priority)->enqueue_front(cl, cost, std::move(item)); |
7c673cae FG |
269 | } |
270 | ||
271 | bool empty() const final { | |
11fdf7f2 TL |
272 | ceph_assert(total_priority >= 0); |
273 | ceph_assert((total_priority == 0) || !(queue.empty())); | |
7c673cae FG |
274 | return queue.empty() && high_queue.empty(); |
275 | } | |
276 | ||
277 | T dequeue() final { | |
11fdf7f2 | 278 | ceph_assert(!empty()); |
7c673cae FG |
279 | |
280 | if (!(high_queue.empty())) { | |
11fdf7f2 | 281 | T ret = std::move(high_queue.rbegin()->second.front().second); |
7c673cae FG |
282 | high_queue.rbegin()->second.pop_front(); |
283 | if (high_queue.rbegin()->second.empty()) { | |
284 | high_queue.erase(high_queue.rbegin()->first); | |
285 | } | |
286 | return ret; | |
287 | } | |
288 | ||
289 | // if there are multiple buckets/subqueues with sufficient tokens, | |
290 | // we behave like a strict priority queue among all subqueues that | |
291 | // are eligible to run. | |
292 | for (typename SubQueues::iterator i = queue.begin(); | |
293 | i != queue.end(); | |
294 | ++i) { | |
11fdf7f2 | 295 | ceph_assert(!(i->second.empty())); |
7c673cae | 296 | if (i->second.front().first < i->second.num_tokens()) { |
7c673cae FG |
297 | unsigned cost = i->second.front().first; |
298 | i->second.take_tokens(cost); | |
11fdf7f2 | 299 | T ret = std::move(i->second.front().second); |
7c673cae FG |
300 | i->second.pop_front(); |
301 | if (i->second.empty()) { | |
302 | remove_queue(i->first); | |
303 | } | |
304 | distribute_tokens(cost); | |
305 | return ret; | |
306 | } | |
307 | } | |
308 | ||
309 | // if no subqueues have sufficient tokens, we behave like a strict | |
310 | // priority queue. | |
7c673cae | 311 | unsigned cost = queue.rbegin()->second.front().first; |
11fdf7f2 | 312 | T ret = std::move(queue.rbegin()->second.front().second); |
7c673cae FG |
313 | queue.rbegin()->second.pop_front(); |
314 | if (queue.rbegin()->second.empty()) { | |
315 | remove_queue(queue.rbegin()->first); | |
316 | } | |
317 | distribute_tokens(cost); | |
318 | return ret; | |
319 | } | |
320 | ||
321 | void dump(ceph::Formatter *f) const final { | |
322 | f->dump_int("total_priority", total_priority); | |
323 | f->dump_int("max_tokens_per_subqueue", max_tokens_per_subqueue); | |
324 | f->dump_int("min_cost", min_cost); | |
325 | f->open_array_section("high_queues"); | |
326 | for (typename SubQueues::const_iterator p = high_queue.begin(); | |
327 | p != high_queue.end(); | |
328 | ++p) { | |
329 | f->open_object_section("subqueue"); | |
330 | f->dump_int("priority", p->first); | |
331 | p->second.dump(f); | |
332 | f->close_section(); | |
333 | } | |
334 | f->close_section(); | |
335 | f->open_array_section("queues"); | |
336 | for (typename SubQueues::const_iterator p = queue.begin(); | |
337 | p != queue.end(); | |
338 | ++p) { | |
339 | f->open_object_section("subqueue"); | |
340 | f->dump_int("priority", p->first); | |
341 | p->second.dump(f); | |
342 | f->close_section(); | |
343 | } | |
344 | f->close_section(); | |
345 | } | |
9f95a23c TL |
346 | |
347 | void print(std::ostream &ostream) const final { | |
348 | ostream << "PrioritizedQueue"; | |
349 | } | |
7c673cae FG |
350 | }; |
351 | ||
352 | #endif |