forked from zhangnaifan/BzTree
-
Notifications
You must be signed in to change notification settings - Fork 0
/
PMwCAS.cpp
504 lines (468 loc) · 14.8 KB
/
PMwCAS.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
#include "PMwCAS.h"
#include "bzconfig.h"
#include "bzerrno.h"
#include <assert.h>
#include <atomic>
#include <stdint.h>
#include <thread>
#ifdef BZ_DEBUG
#include <iomanip>
#include <fstream>
#include <mutex>
std::mutex flag;
std::fstream mem_fs("memory.txt", std::ios::app);
#endif // BZ_DEBUG
using namespace std;
uint64_t GC_CAN_QUIT = 0;
uint64_t GC_BUSY = 1;
uint64_t GC_QUIT = 2;
uint64_t gc_alive = GC_CAN_QUIT;
/* set desc status to FREE */
void pmwcas_first_use(mdesc_pool_t pool, PMEMobjpool *pop, PMEMoid oid) {
for (off_t i = 0; i < DESCRIPTOR_POOL_SIZE; ++i) {
pool->mdescs[i].status = ST_FREE;
persist(&pool->mdescs[i].status, sizeof(pool->mdescs[i].status));
}
for (off_t i = 0; i < WORD_DESCRIPTOR_SIZE; ++i) {
pool->magic[i] = 0;
persist(&pool->magic[i], sizeof(uint64_t));
}
pool->mem_.init(pop, oid);
pool->mem_.prev_alloc();
}
void pmwcas_reclaim(gc_entry_t *entry, void *arg);
/*
* set base address
* set mdesc_pool ptr
* init gc
*/
int pmwcas_init(mdesc_pool_t pool, PMEMoid oid, PMEMobjpool * pop)
{
/* base address */
rel_ptr<uint64_t>::set_base(oid);
rel_ptr<word_entry>::set_base(oid);
rel_ptr<pmwcas_entry>::set_base(oid);
/* mdesc_pool */
for (off_t i = 0; i < DESCRIPTOR_POOL_SIZE; ++i)
{
pool->mdescs[i].mdesc_pool = pool;
}
/* init gc */
if (!(pool->gc = gc_create(offsetof(struct pmwcas_entry, gc_entry), pmwcas_reclaim, (void*)pool)))
return EGCCREAT;
/* init mem_pool */
pool->mem_.init(pop, oid);
/* 创建GC线程 */
gc_alive = GC_CAN_QUIT;
for (int i = 0; i < GC_THREADS_COUNT; ++i) {
std::thread gc([pool] {
// uint64_t gc_rd;
while (true) {
do {
__sync_bool_compare_and_swap(&gc_alive, GC_CAN_QUIT, GC_BUSY);
} while (gc_alive == GC_BUSY);
if (gc_alive == GC_QUIT)
break;
assert(pool->gc);
gc_cycle(pool->gc);
__sync_bool_compare_and_swap(&gc_alive, GC_BUSY, GC_CAN_QUIT);
std::this_thread::sleep_for(
std::chrono::milliseconds(GC_WAIT_MS));
}
});
gc.detach();
}
return 0;
}
void pmwcas_finish(mdesc_pool_t pool)
{
while (!__sync_bool_compare_and_swap(&gc_alive, GC_CAN_QUIT, GC_QUIT))
;
gc_full(pool->gc, 50);
gc_destroy(pool->gc);
pool->gc = nullptr;
}
/* allocate a PMwCAS desc; enter crit; return base_address if failed */
mdesc_t pmwcas_alloc(mdesc_pool_t pool, off_t recycle_policy, off_t search_pos)
{
if (recycle_policy > 2)
{
return mdesc_t::null();
}
for (off_t i = 0; i < DESCRIPTOR_POOL_SIZE; ++i)
{
off_t pos = (i + search_pos) % DESCRIPTOR_POOL_SIZE;
if (pool->mdescs[pos].status == ST_FREE)
{
__sync_bool_compare_and_swap(&pool->mdescs[pos].status,
ST_FREE, ST_UNDECIDED);
if (pool->mdescs[pos].status == ST_FREE) {
pool->mdescs[pos].count = 0;
persist((uint64_t *)&pool->mdescs[pos].count,
sizeof(uint64_t));
pool->mdescs[pos].callback = recycle_policy;
persist((uint64_t *)&pool->mdescs[pos].callback,
sizeof(uint64_t));
return &pool->mdescs[pos];
}
}
}
return mdesc_t::null();
}
bool pmwcas_abort(mdesc_t mdesc)
{
return __sync_bool_compare_and_swap(&mdesc->status, ST_UNDECIDED, ST_FREE);
}
rel_ptr<uint64_t> get_magic(mdesc_pool_t pool, int magic)
{
return rel_ptr<uint64_t>(&pool->magic[magic]);
}
/* exit crit; add PMwCAS entry to gc list */
void pmwcas_free(mdesc_t mdesc)
{
//gc_crit_exit(mdesc->mdesc_pool->gc);
gc_limbo(mdesc->mdesc_pool->gc, mdesc.abs());
}
/* reset desc status to FREE; reclaim memory accoding to policy */
void pmwcas_reclaim(gc_entry_t *entry, void *arg)
{
mdesc_pool_t pool = (mdesc_pool_t)arg;
const off_t off = pool->gc->entry_off;
mdesc_t mdesc;
while (entry) {
mdesc = (mdesc_t)(pmwcas_entry *)((unsigned char *)entry - off);
entry = entry->next;
for (off_t j = 0; j < mdesc->count; ++j) {
wdesc_t wdesc = mdesc->wdescs + j;
bool done = mdesc->status == ST_SUCCESS;
uint64_t val = done ? wdesc->new_val : wdesc->expect;
/* 根据回收规则回收 */
if (wdesc->recycle_func == NOCAS_RELEASE_ADDR_ON_SUCCESS && done &&
!wdesc->addr.is_null()) {
pmwcas_word_recycle(pool, &wdesc->addr);
} else if (wdesc->recycle_func == NOCAS_EXECUTE_ON_FAILED &&
!done) {
__sync_bool_compare_and_swap(wdesc->addr.abs(), wdesc->expect,
wdesc->new_val);
} else if (wdesc->recycle_func == NOCAS_RELEASE_NEW_ON_FAILED &&
!done && wdesc->new_val) {
pmwcas_word_recycle(pool, (rel_ptr<uint64_t> *)&wdesc->new_val);
}
if ((wdesc->recycle_func == RELEASE_NEW_ON_FAILED ||
wdesc->recycle_func == RELEASE_SWAP_PTR) &&
!done && wdesc->new_val) {
pmwcas_word_recycle(pool, (rel_ptr<uint64_t> *)&wdesc->new_val);
}
if ((wdesc->recycle_func == RELEASE_EXP_ON_SUCCESS ||
wdesc->recycle_func == RELEASE_SWAP_PTR) &&
done && wdesc->expect) {
/* 成功时回收expect */
pmwcas_word_recycle(pool, (rel_ptr<uint64_t> *)&wdesc->expect);
}
}
/* we have persist all the target words to the correct state */
mdesc->status = ST_FREE;
persist(&mdesc->status, sizeof(mdesc->status));
}
}
/* 回收内存 */
void pmwcas_word_recycle(mdesc_pool_t pool, rel_ptr<rel_ptr<uint64_t>> ptr_leak)
{
pool->mem_.release(ptr_leak);
//pmemobj_free(&ptr_leak.oid());
#ifdef BZ_DEBUG
flag.lock();
mem_fs << "RECYCLE " << std::setfill('0') << std::setw(16) << std::hex << ptr_leak.rel() << "\n";
flag.unlock();
#endif // BZ_DEBUG
}
/*
* add a word entry to PMwCAS desc
* expect and new_val must be common variables whose higher 12 bits are 0
*/
bool pmwcas_add(mdesc_t mdesc, rel_ptr<uint64_t> addr, uint64_t expect, uint64_t new_val, off_t recycle)
{
/* check if PMwCAS is full */
if (mdesc->count == WORD_DESCRIPTOR_SIZE)
{
assert(0);
return false;
}
/*
* check if the target address exists
* otherwise, find the insert point
*/
for (off_t i = 0; i < mdesc->count; ++i)
{
wdesc_t wdesc = mdesc->wdescs + i;
if (wdesc->addr == addr)
{
assert(0);
return false;
}
}
wdesc_t wdesc = mdesc->wdescs + mdesc->count;
wdesc->addr = addr;
wdesc->expect = expect;
wdesc->new_val = new_val;
wdesc->mdesc = mdesc;
wdesc->recycle_func = !recycle ? mdesc->callback : recycle;
persist(wdesc.abs(), sizeof(*wdesc));
++mdesc->count;
persist(&mdesc->count, sizeof(uint64_t));
return true;
}
inline bool is_RDCSS(uint64_t val)
{
return (val & RDCSS_BIT) != 0ULL;
}
inline bool is_MwCAS(uint64_t val)
{
return (val & MwCAS_BIT) != 0ULL;
}
inline bool is_dirty(uint64_t val)
{
return (val & DIRTY_BIT) != 0ULL;
}
inline void persist_clear(uint64_t *addr, uint64_t val) {
persist(addr, sizeof(uint64_t));
__sync_bool_compare_and_swap(addr, val, val & ~DIRTY_BIT);
}
inline void complete_install(wdesc_t wdesc)
{
uint64_t mdesc_ptr = wdesc->mdesc.rel() | MwCAS_BIT | DIRTY_BIT;
uint64_t wdesc_ptr = wdesc.rel() | RDCSS_BIT;
bool test = wdesc->mdesc->status == ST_UNDECIDED;
__sync_bool_compare_and_swap(wdesc->addr.abs(), wdesc_ptr,
test ? mdesc_ptr : wdesc->expect);
}
inline uint64_t install_mdesc(wdesc_t wdesc)
{
uint64_t ptr = wdesc.rel() | RDCSS_BIT;
uint64_t r;
while (true)
{
auto r = __sync_val_compare_and_swap(wdesc->addr.abs(), ptr,
wdesc->expect);
if (is_RDCSS(r)) {
complete_install(
wdesc_t((uintptr_t)wdesc->addr.abs() & (uintptr_t)ADDR_MASK));
continue;
}
if (r == wdesc->expect)
{
complete_install(wdesc);
}
break;
}
return r;
}
void sort_addr(off_t arr[], mdesc_t mdesc) {
for (off_t i = 0; i < mdesc->count; ++i) {
arr[i] = i;
}
for (int i = 0; i < mdesc->count; ++i) {
int cur_min_pos = i;
rel_ptr<uint64_t> cur_min(mdesc->wdescs[arr[i]].addr);
for (int j = i + 1; j < mdesc->count; ++j)
if (mdesc->wdescs[arr[j]].addr < cur_min) {
cur_min = mdesc->wdescs[arr[j]].addr;
cur_min_pos = j;
}
if (cur_min_pos != i) {
off_t tmp = arr[cur_min_pos];
arr[cur_min_pos] = arr[i];
arr[i] = tmp;
}
}
}
bool pmwcas_commit(mdesc_t mdesc)
{
uint64_t status = ST_SUCCESS;
off_t index[WORD_DESCRIPTOR_SIZE];
sort_addr(index, mdesc);
for (off_t i = 0; status == ST_SUCCESS && i < mdesc->count; ++i) {
wdesc_t wdesc = mdesc->wdescs + index[i];
if (wdesc->recycle_func == NOCAS_RELEASE_ADDR_ON_SUCCESS
|| wdesc->recycle_func == NOCAS_EXECUTE_ON_FAILED
|| wdesc->recycle_func == NOCAS_RELEASE_NEW_ON_FAILED)
continue;
uint64_t r;
while (true) {
/* try to install a pointer to mdesc for tha target word */
r = install_mdesc(wdesc);
uint64_t tmp = wdesc->expect;
if (r == wdesc->expect || (r & ADDR_MASK) == mdesc.rel()) {
/* successful CAS install or has been installed by another thread */
break;
}
if (is_MwCAS(r)) {
/* read a multi word decriptor help it finish */
if (is_dirty(r)) {
/* make sure what we read is persistent */
persist_clear(wdesc->addr.abs(), r);
}
pmwcas_commit(mdesc_t(r & ADDR_MASK));
/* retry install */
continue;
}
/* otherwise, CAS failed, so the whole PMwCAS fails */
status = ST_FAILED;
break;
}
}
uint64_t mdesc_ptr = mdesc.rel() | DIRTY_BIT | MwCAS_BIT;
/*
* make sure that every target word is installed
*/
if (status == ST_SUCCESS) {
for (off_t i = 0; i < mdesc->count; ++i) {
wdesc_t wdesc = mdesc->wdescs + index[i];
if (wdesc->recycle_func == NOCAS_RELEASE_ADDR_ON_SUCCESS
|| wdesc->recycle_func == NOCAS_EXECUTE_ON_FAILED
|| wdesc->recycle_func == NOCAS_RELEASE_NEW_ON_FAILED)
continue;
persist_clear(wdesc->addr.abs(), mdesc_ptr);
}
}
/* finalize MwCAS status */
__sync_bool_compare_and_swap(&mdesc->status, ST_UNDECIDED,
status | DIRTY_BIT);
persist_clear(&mdesc->status, mdesc->status);
/* install the final value for each word */
for (off_t i = 0; i < mdesc->count; ++i) {
wdesc_t wdesc = mdesc->wdescs + index[i];
if (wdesc->recycle_func == NOCAS_RELEASE_ADDR_ON_SUCCESS
|| wdesc->recycle_func == NOCAS_EXECUTE_ON_FAILED
|| wdesc->recycle_func == NOCAS_RELEASE_NEW_ON_FAILED)
continue;
uint64_t val =
(mdesc->status == ST_SUCCESS ? wdesc->new_val : wdesc->expect) | DIRTY_BIT;
auto r = __sync_val_compare_and_swap(wdesc->addr.abs(),
mdesc_ptr, val);
/* if the dirty bit has been unset */
if (r == (mdesc_ptr & ~DIRTY_BIT)) {
__sync_bool_compare_and_swap(wdesc->addr.abs(),
mdesc_ptr & ~DIRTY_BIT, val);
}
persist_clear(wdesc->addr.abs(), val);
}
return mdesc->status == ST_SUCCESS;
}
uint64_t pmwcas_read(uint64_t * addr)
{
uint64_t r;
while (true)
{
r = *addr;
if (is_RDCSS(r))
{
complete_install(wdesc_t(r & ADDR_MASK));
continue;
}
if (is_dirty(r))
{
persist_clear(addr, r);
r &= ~DIRTY_BIT;
}
if (is_MwCAS(r))
{
pmwcas_commit(mdesc_t(r & ADDR_MASK));
continue;
}
break;
}
assert(!(r & MwCAS_BIT || r & DIRTY_BIT || r & RDCSS_BIT));
return r;
}
/*
* recovery process(in a single thread manner):
* 1) roll back failed or in-flight PMwCAS
* 2) finish success PMwCAS
* 3) reclaim PMwCAS descriptor
*/
void pmwcas_recovery(mdesc_pool_t pool)
{
for (off_t i = 0; i < DESCRIPTOR_POOL_SIZE; ++i)
{
mdesc_t mdesc = pool->mdescs + i;
/*
* clear dirty bit in persistent memory,
* this is because crash happens before CPU flushes the newest cache line
* back to persistent memory
*/
if (is_dirty(mdesc->status))
{
mdesc->status &= ~DIRTY_BIT;
persist(&mdesc->status, sizeof(mdesc->status));
}
if (mdesc->status == ST_FREE)
{
continue;
}
bool done = mdesc->status == ST_SUCCESS;
uint64_t mdesc_ptr = mdesc.rel() | MwCAS_BIT | DIRTY_BIT;
/*
* each target word could remain:
* 1) old value
* 2) ptr to word descriptor
* 3) ptr to multi-word descriptor
* 4) new val
*/
for (off_t j = 0; j < mdesc->count; ++j)
{
wdesc_t wdesc = mdesc->wdescs + j;
uint64_t r, val = done ? wdesc->new_val : wdesc->expect;
/* case (3) when dirty bit set */
r = __sync_val_compare_and_swap(wdesc->addr.abs(),
mdesc_ptr, val);
/* case (3) when the dirty bit unset */
if (r == (mdesc_ptr & ~DIRTY_BIT)) {
__sync_bool_compare_and_swap(
wdesc->addr.abs(), mdesc_ptr & ~DIRTY_BIT, val);
}
/* case (2) */
if (r & RDCSS_BIT)
{
__sync_val_compare_and_swap(wdesc->addr.abs(),
wdesc.rel() | RDCSS_BIT,
wdesc->expect);
}
/*
* if all CASs above fail,
* target word remain in case (1) or case (4)
* no need to modify
*/
persist(wdesc->addr.abs(), sizeof(*wdesc->addr));
/* 根据回收规则回收 */
if (wdesc->recycle_func == NOCAS_RELEASE_ADDR_ON_SUCCESS
&& done && !wdesc->addr.is_null()) {
pmwcas_word_recycle(pool, &wdesc->addr);
}
else if (wdesc->recycle_func == NOCAS_EXECUTE_ON_FAILED
&& !done) {
__sync_bool_compare_and_swap(
wdesc->addr.abs(), wdesc->expect, wdesc->new_val);
}
else if (wdesc->recycle_func == NOCAS_RELEASE_NEW_ON_FAILED
&& !done && wdesc->new_val) {
pmwcas_word_recycle(pool, (rel_ptr<uint64_t>*)&wdesc->new_val);
}
else if ((wdesc->recycle_func == RELEASE_NEW_ON_FAILED
|| wdesc->recycle_func == RELEASE_SWAP_PTR)
&& !done && wdesc->new_val) {
pmwcas_word_recycle(pool, (rel_ptr<uint64_t>*)&wdesc->new_val);
}
else if ((wdesc->recycle_func == RELEASE_EXP_ON_SUCCESS
|| wdesc->recycle_func == RELEASE_SWAP_PTR)
&& done && wdesc->expect) {
/* 成功时回收expect */
pmwcas_word_recycle(
pool, (rel_ptr<uint64_t> *)&wdesc->expect);
}
}
/* we have persist all the target words to the correct state */
mdesc->status = ST_FREE;
persist(&mdesc->status, sizeof(mdesc->status));
}
}