a0f30c5195ababb422562ffb0f0aa3cd84b4c693
[m6w6/libmemcached] / pool.cc
1 /* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
2 *
3 * Libmemcached library
4 *
5 * Copyright (C) 2011 Data Differential, http://datadifferential.com/
6 * Copyright (C) 2010 Brian Aker All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are
10 * met:
11 *
12 * * Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * * Redistributions in binary form must reproduce the above
16 * copyright notice, this list of conditions and the following disclaimer
17 * in the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * * The names of its contributors may not be used to endorse or
21 * promote products derived from this software without specific prior
22 * written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
25 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
26 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
27 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
28 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
30 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
34 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 *
36 */
37
38
39 #include <libmemcachedutil/common.h>
40
41 #include <cassert>
42 #include <cerrno>
43 #include <pthread.h>
44 #include <memory>
45
46 struct memcached_pool_st
47 {
48 pthread_mutex_t mutex;
49 pthread_cond_t cond;
50 memcached_st *master;
51 memcached_st **server_pool;
52 int firstfree;
53 const uint32_t size;
54 uint32_t current_size;
55 bool _owns_master;
56 struct timespec _timeout;
57
58 memcached_pool_st(memcached_st *master_arg, size_t max_arg) :
59 master(master_arg),
60 server_pool(NULL),
61 firstfree(-1),
62 size(max_arg),
63 current_size(0),
64 _owns_master(false)
65 {
66 pthread_mutex_init(&mutex, NULL);
67 pthread_cond_init(&cond, NULL);
68 _timeout.tv_sec= 5;
69 _timeout.tv_nsec= 0;
70 }
71
72 const struct timespec& timeout() const
73 {
74 return _timeout;
75 }
76
77 bool release(memcached_st*, memcached_return_t& rc);
78
79 memcached_st *fetch(memcached_return_t& rc);
80 memcached_st *fetch(const struct timespec&, memcached_return_t& rc);
81
82 bool init(uint32_t initial);
83
84 ~memcached_pool_st()
85 {
86 for (int x= 0; x <= firstfree; ++x)
87 {
88 memcached_free(server_pool[x]);
89 server_pool[x] = NULL;
90 }
91
92 pthread_mutex_destroy(&mutex);
93 pthread_cond_destroy(&cond);
94 delete [] server_pool;
95 if (_owns_master)
96 {
97 memcached_free(master);
98 }
99 }
100
101 void increment_version()
102 {
103 ++master->configure.version;
104 }
105
106 bool compare_version(const memcached_st *arg) const
107 {
108 return (arg->configure.version == version());
109 }
110
111 int32_t version() const
112 {
113 return master->configure.version;
114 }
115 };
116
117
118 /**
119 * Grow the connection pool by creating a connection structure and clone the
120 * original memcached handle.
121 */
122 static bool grow_pool(memcached_pool_st* pool)
123 {
124 assert(pool);
125
126 memcached_st *obj;
127 if (not (obj= memcached_clone(NULL, pool->master)))
128 {
129 return false;
130 }
131
132 pool->server_pool[++pool->firstfree]= obj;
133 pool->current_size++;
134 obj->configure.version= pool->version();
135
136 return true;
137 }
138
139 bool memcached_pool_st::init(uint32_t initial)
140 {
141 server_pool= new (std::nothrow) memcached_st *[size];
142 if (not server_pool)
143 return false;
144
145 /*
146 Try to create the initial size of the pool. An allocation failure at
147 this time is not fatal..
148 */
149 for (unsigned int x= 0; x < initial; ++x)
150 {
151 if (grow_pool(this) == false)
152 {
153 break;
154 }
155 }
156
157 return true;
158 }
159
160
161 static inline memcached_pool_st *_pool_create(memcached_st* master, uint32_t initial, uint32_t max)
162 {
163 if (initial == 0 or max == 0 or (initial > max))
164 {
165 return NULL;
166 }
167
168 memcached_pool_st *object= new (std::nothrow) memcached_pool_st(master, max);
169 if (object == NULL)
170 {
171 return NULL;
172 }
173
174 /*
175 Try to create the initial size of the pool. An allocation failure at
176 this time is not fatal..
177 */
178 if (not object->init(initial))
179 {
180 delete object;
181 return NULL;
182 }
183
184 return object;
185 }
186
187 memcached_pool_st *memcached_pool_create(memcached_st* master, uint32_t initial, uint32_t max)
188 {
189 return _pool_create(master, initial, max);
190 }
191
192 memcached_pool_st * memcached_pool(const char *option_string, size_t option_string_length)
193 {
194 memcached_st *memc= memcached(option_string, option_string_length);
195
196 if (memc == NULL)
197 {
198 return NULL;
199 }
200
201 memcached_pool_st *self= memcached_pool_create(memc, memc->configure.initial_pool_size, memc->configure.max_pool_size);
202 if (self == NULL)
203 {
204 memcached_free(memc);
205 return NULL;
206 }
207
208 self->_owns_master= true;
209
210 return self;
211 }
212
213 memcached_st* memcached_pool_destroy(memcached_pool_st* pool)
214 {
215 if (pool == NULL)
216 {
217 return NULL;
218 }
219
220 // Legacy that we return the original structure
221 memcached_st *ret= NULL;
222 if (pool->_owns_master)
223 { }
224 else
225 {
226 ret= pool->master;
227 }
228
229 delete pool;
230
231 return ret;
232 }
233
234 memcached_st* memcached_pool_st::fetch(memcached_return_t& rc)
235 {
236 static struct timespec relative_time= { 0, 0 };
237 return fetch(relative_time, rc);
238 }
239
240 memcached_st* memcached_pool_st::fetch(const struct timespec& relative_time, memcached_return_t& rc)
241 {
242 rc= MEMCACHED_SUCCESS;
243
244 if (pthread_mutex_lock(&mutex))
245 {
246 rc= MEMCACHED_IN_PROGRESS;
247 return NULL;
248 }
249
250 memcached_st *ret= NULL;
251 do
252 {
253 if (firstfree > -1)
254 {
255 ret= server_pool[firstfree--];
256 }
257 else if (current_size == size)
258 {
259 if (relative_time.tv_sec == 0 and relative_time.tv_nsec == 0)
260 {
261 pthread_mutex_unlock(&mutex);
262 rc= MEMCACHED_NOTFOUND;
263
264 return NULL;
265 }
266
267 struct timespec time_to_wait= {0, 0};
268 time_to_wait.tv_sec= time(NULL) +relative_time.tv_sec;
269 time_to_wait.tv_nsec= relative_time.tv_nsec;
270
271 int thread_ret;
272 if ((thread_ret= pthread_cond_timedwait(&cond, &mutex, &time_to_wait)) != 0)
273 {
274 pthread_mutex_unlock(&mutex);
275
276 if (thread_ret == ETIMEDOUT)
277 {
278 rc= MEMCACHED_TIMEOUT;
279 }
280 else
281 {
282 errno= thread_ret;
283 rc= MEMCACHED_ERRNO;
284 }
285
286 return NULL;
287 }
288 }
289 else if (grow_pool(this) == false)
290 {
291 (void)pthread_mutex_unlock(&mutex);
292 return NULL;
293 }
294 } while (ret == NULL);
295
296 pthread_mutex_unlock(&mutex);
297
298 return ret;
299 }
300
301 bool memcached_pool_st::release(memcached_st *released, memcached_return_t& rc)
302 {
303 rc= MEMCACHED_SUCCESS;
304 if (released == NULL)
305 {
306 rc= MEMCACHED_INVALID_ARGUMENTS;
307 return false;
308 }
309
310 if (pthread_mutex_lock(&mutex))
311 {
312 rc= MEMCACHED_IN_PROGRESS;
313 return false;
314 }
315
316 /*
317 Someone updated the behavior on the object, so we clone a new memcached_st with the new settings. If we fail to clone, we keep the old one around.
318 */
319 if (compare_version(released) == false)
320 {
321 memcached_st *memc;
322 if ((memc= memcached_clone(NULL, master)))
323 {
324 memcached_free(released);
325 released= memc;
326 }
327 }
328
329 server_pool[++firstfree]= released;
330
331 if (firstfree == 0 and current_size == size)
332 {
333 /* we might have people waiting for a connection.. wake them up :-) */
334 pthread_cond_broadcast(&cond);
335 }
336
337 (void)pthread_mutex_unlock(&mutex);
338
339 return true;
340 }
341
342 memcached_st* memcached_pool_fetch(memcached_pool_st* pool, struct timespec* relative_time, memcached_return_t* rc)
343 {
344 if (pool == NULL)
345 {
346 return NULL;
347 }
348
349 memcached_return_t unused;
350 if (rc == NULL)
351 {
352 rc= &unused;
353 }
354
355 if (relative_time == NULL)
356 {
357 return pool->fetch(*rc);
358 }
359
360 return pool->fetch(*relative_time, *rc);
361 }
362
363 memcached_st* memcached_pool_pop(memcached_pool_st* pool,
364 bool block,
365 memcached_return_t *rc)
366 {
367 if (pool == NULL)
368 {
369 return NULL;
370 }
371
372 memcached_return_t unused;
373 if (rc == NULL)
374 {
375 rc= &unused;
376 }
377
378 memcached_st *memc;
379 if (block)
380 {
381 memc= pool->fetch(pool->timeout(), *rc);
382 }
383 else
384 {
385 memc= pool->fetch(*rc);
386 }
387
388 return memc;
389 }
390
391 memcached_return_t memcached_pool_release(memcached_pool_st* pool, memcached_st *released)
392 {
393 if (pool == NULL)
394 {
395 return MEMCACHED_INVALID_ARGUMENTS;
396 }
397
398 memcached_return_t rc;
399
400 (void) pool->release(released, rc);
401
402 return rc;
403 }
404
405 memcached_return_t memcached_pool_push(memcached_pool_st* pool, memcached_st *released)
406 {
407 return memcached_pool_release(pool, released);
408 }
409
410
411 memcached_return_t memcached_pool_behavior_set(memcached_pool_st *pool,
412 memcached_behavior_t flag,
413 uint64_t data)
414 {
415 if (pool == NULL)
416 {
417 return MEMCACHED_INVALID_ARGUMENTS;
418 }
419
420 if (pthread_mutex_lock(&pool->mutex))
421 {
422 return MEMCACHED_IN_PROGRESS;
423 }
424
425 /* update the master */
426 memcached_return_t rc= memcached_behavior_set(pool->master, flag, data);
427 if (memcached_failed(rc))
428 {
429 (void)pthread_mutex_unlock(&pool->mutex);
430 return rc;
431 }
432
433 pool->increment_version();
434 /* update the clones */
435 for (int xx= 0; xx <= pool->firstfree; ++xx)
436 {
437 if (memcached_success(memcached_behavior_set(pool->server_pool[xx], flag, data)))
438 {
439 pool->server_pool[xx]->configure.version= pool->version();
440 }
441 else
442 {
443 memcached_st *memc;
444 if ((memc= memcached_clone(NULL, pool->master)))
445 {
446 memcached_free(pool->server_pool[xx]);
447 pool->server_pool[xx]= memc;
448 /* I'm not sure what to do in this case.. this would happen
449 if we fail to push the server list inside the client..
450 I should add a testcase for this, but I believe the following
451 would work, except that you would add a hole in the pool list..
452 in theory you could end up with an empty pool....
453 */
454 }
455 }
456 }
457
458 (void)pthread_mutex_unlock(&pool->mutex);
459
460 return rc;
461 }
462
463 memcached_return_t memcached_pool_behavior_get(memcached_pool_st *pool,
464 memcached_behavior_t flag,
465 uint64_t *value)
466 {
467 if (pool == NULL)
468 {
469 return MEMCACHED_INVALID_ARGUMENTS;
470 }
471
472 if (pthread_mutex_lock(&pool->mutex))
473 {
474 return MEMCACHED_IN_PROGRESS;
475 }
476
477 *value= memcached_behavior_get(pool->master, flag);
478
479 (void)pthread_mutex_unlock(&pool->mutex);
480
481 return MEMCACHED_SUCCESS;
482 }