forked from yuanrongxi/innodb
-
Notifications
You must be signed in to change notification settings - Fork 0
/
buf0buf.cc
1138 lines (866 loc) · 29.2 KB
/
buf0buf.cc
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
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#include "buf0buf.h"
#include "mem0mem.h"
#include "btr0btr.h"
#include "fil0fil.h"
#include "lock0lock.h"
#include "btr0sea.h"
#include "ibuf0ibuf.h"
#include "dict0dict.h"
#include "log0recv.h"
#include "trx0undo.h"
#include "srv0srv.h"
buf_pool_t* buf_pool = NULL;
ulint buf_dbg_counter = 0;
ibool buf_debug_prints = FALSE;
/*计算一个page内容的checksum值*/
ulint buf_calc_page_checksum(byte* page)
{
ulint checksum;
checksum = ut_fold_binary(page, FIL_PAGE_FILE_FLUSH_LSN) + ut_fold_binary(page + FIL_PAGE_DATA, UNIV_PAGE_SIZE - FIL_PAGE_DATA - FIL_PAGE_END_LSN);
checksum = checksum & 0xFFFFFFFF;
return checksum;
}
/*判断page是否损坏了,一般是从磁盘将page导入缓冲池时要做判断*/
ibool buf_page_is_corrupted(byte* read_buf)
{
ulint checksum;
checksum = buf_calc_page_checksum(read_buf);
/*校验page的LSN和checksum*/
if((mach_read_from_4(read_buf + FIL_PAGE_LSN + 4) != mach_read_from_4(read_buf + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN + 4))
|| (checksum != mach_read_from_4(read_buf + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN)
&& mach_read_from_4(read_buf + FIL_PAGE_LSN) != mach_read_from_4(read_buf + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN)))
return TRUE;
return FALSE;
}
/*打印page的错误信息,一般是在buf_page_is_corrupted判断后做错误输出*/
void buf_page_print(byte* read_buf)
{
dict_index_t* index;
ulint checksum;
char* buf;
buf = mem_alloc(4 * UNIV_PAGE_SIZE);
ut_sprintf_buf(buf, read_buf, UNIV_PAGE_SIZE);
ut_print_timestamp(stderr);
fprintf(stderr, " InnoDB: Page dump in ascii and hex (%lu bytes):\n%s", (ulint)UNIV_PAGE_SIZE, buf);
fprintf(stderr, "InnoDB: End of page dump\n");
mem_free(buf);
checksum = buf_calc_page_checksum(read_buf);
ut_print_timestamp(stderr);
fprintf(stderr, " InnoDB: Page checksum %lu stored checksum %lu\n",
checksum, mach_read_from_4(read_buf+ UNIV_PAGE_SIZE - FIL_PAGE_END_LSN));
fprintf(stderr, "InnoDB: Page lsn %lu %lu, low 4 bytes of lsn at page end %lu\n",
mach_read_from_4(read_buf + FIL_PAGE_LSN),
mach_read_from_4(read_buf + FIL_PAGE_LSN + 4),
mach_read_from_4(read_buf + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN + 4));
if (mach_read_from_2(read_buf + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_TYPE) == TRX_UNDO_INSERT)
fprintf(stderr, "InnoDB: Page may be an insert undo log page\n");
else if(mach_read_from_2(read_buf + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_TYPE) == TRX_UNDO_UPDATE)
fprintf(stderr, "InnoDB: Page may be an update undo log page\n");
if(fil_page_get_type(read_buf) == FIL_PAGE_INDEX) {
fprintf(stderr, "InnoDB: Page may be an index page ");
fprintf(stderr, "where index id is %lu %lu\n",
ut_dulint_get_high(btr_page_get_index_id(read_buf)),
ut_dulint_get_low(btr_page_get_index_id(read_buf)));
index = dict_index_find_on_id_low(btr_page_get_index_id(read_buf));
if (index)
fprintf(stderr, "InnoDB: and table %s index %s\n", index->table_name, index->name);
}
}
/*初始化一个buf_block*/
static void buf_block_init(buf_block_t* block, byte* frame)
{
/*初始化状态信息*/
block->state = BUF_BLOCK_NOT_USED;
block->frame = frame;
block->modify_clock = ut_dulint_zero;
block->file_page_was_freed = FALSE;
/*初始化latch*/
rw_lock_create(&(block->lock));
ut_ad(rw_lock_validate(&(block->lock)));
rw_lock_create(&(block->read_lock));
rw_lock_set_level(&(block->read_lock), SYNC_NO_ORDER_CHECK);
rw_lock_create(&(block->debug_latch));
rw_lock_set_level(&(block->debug_latch), SYNC_NO_ORDER_CHECK);
}
/*创建buf_poot_t对象*/
static buf_pool_t* buf_pool_create(ulint max_size, ulint curr_size)
{
byte* frame;
ulint i;
buf_block_t* block;
ut_a(max_size == curr_size);
buf_pool = mem_alloc(sizeof(buf_pool_t));
/*初始化常规参数*/
mutex_create(&(buf_pool->mutex));
mutex_set_level(&(buf_pool->mutex), SYNC_BUF_POOL);
mutex_enter(&(uf_pool->mutex));
/*开辟一块max_size个page size大小的内存作为缓冲池,这里的+1是为了UNIV_PAGE_SIZE对齐*/
buf_pool->frame_mem = ut_malloc(UNIV_PAGE_SIZE * (max_size + 1));
if(buf_pool->frame_mem == NULL)
return NULL;
/*开辟一个长度为max_size的block数组*/
buf_pool->blocks = ut_malloc(max_size * sizeof(buf_block_t));
if(buf_pool->blocks == NULL)
return NULL;
buf_pool->max_size = max_size;
buf_pool->curr_size = curr_size;
/*在frame_mem上分配一个frame page,作为frame_zero*/
frame = ut_align(buf_pool->frame_mem, UNIV_PAGE_SIZE);
buf_pool->frame_zero = frame;
buf_pool->high_end = frame + UNIV_PAGE_SIZE * curr_size;
/*对所有block进行初始化，并建立与各个frame之间的关系*/
for(i = 0; i < max_size; i ++){
block = buf_pool_get_nth_block(buf_pool, i);
buf_block_init(block, frame);
frame = frame + UNIV_PAGE_SIZE;
}
buf_pool->page_hash = hash_create(2 * max_size);
buf_pool->n_pend_reads = 0;
buf_pool->last_printout_time = time(NULL);
buf_pool->n_pages_read = 0;
buf_pool->n_pages_written = 0;
buf_pool->n_pages_created = 0;
buf_pool->n_page_gets = 0;
buf_pool->n_page_gets_old = 0;
buf_pool->n_pages_read_old = 0;
buf_pool->n_pages_written_old = 0;
buf_pool->n_pages_created_old = 0;
/*对flush list做初始化*/
UT_LIST_INIT(buf_pool->flush_list);
for(i = BUF_FLUSH_LRU; i <= BUF_FLUSH_LIST; i ++){
buf_pool->n_flush[i] = 0;
buf_pool->init_flush[i] = FALSE;
buf_pool->no_flush[i] = os_event_create(NULL);
}
buf_pool->LRU_flush_ended = 0;
buf_pool->ulint_clock = 1;
buf_pool->freed_page_clock = 0;
/*对LRU LIST初始化*/
UT_LIST_INIT(buf_pool->LRU);
buf_pool->LRU_old = 0;
/*将闲置的buf_block放入free list当中*/
UT_LIST_INIT(buf_pool->free);
for(i = 0; i < curr_size; i ++){
block = buf_pool_get_nth_block(buf_pool, i);
memset(block->frame, '\0', UNIV_PAGE_SIZE);
UT_LIST_ADD_FIRST(free, buf_pool->free, block);
}
mutex_exit(&(buf_pool->mutex));
/*建立自适应HASH索引,根据最大可以缓冲的page数作为hash桶个数*/
btr_search_sys_create(curr_size * UNIV_PAGE_SIZE / sizeof(void*) / 64);
return buf_pool;
}
/*初始化缓冲池，一般在MYSQL启动的时候调用*/
void buf_pool_init(ulint max_size, ulint curr_size)
{
ut_a(buf_pool == NULL);
buf_pool_create(max_size, curr_size);
ut_ad(buf_validate());
}
/*分配一个buf block*/
UNIV_INLINE buf_block_t* buf_block_alloc()
{
return buf_LRU_get_free_block();
}
/*将block从old LRU LIST移到young中，就是LRU List的开始位置*/
UNIV_INLINE void buf_block_make_young(buf_block_t* block)
{
if(buf_pool->freed_page_clock >= block->freed_page_clock + 1 + (buf_pool->curr_size / 1024))
buf_LRU_make_block_young(block);
}
/*释放一个block*/
UNIV_INLINE void buf_block_free(buf_block_t* block)
{
ut_ad(block->state != BUF_BLOCK_FILE_PAGE);
mutex_enter(&(buf_pool->mutex));
buf_LRU_block_free_non_file_page(block);
mutex_exit(&(buf_pool->mutex));
}
/*分配一个buffer frame*/
buf_frame_t* buf_frame_alloc()
{
return buf_block_alloc()->frame;
}
/*释放一个buffer frame*/
void buf_frame_free(buf_frame_t* frame)
{
buf_block_free(buf_block_align(frame));
}
/*通过space id和page no定位到对应的buf_block*/
buf_block_t* buf_page_peek_block(ulint space, ulint offset)
{
buf_block_t* block;
mutex_enter_fast(&(buf_pool->mutex));
block = buf_page_hash_get(space, offset);
mutex_exit(&(buf_pool->mutex));
}
/*通过space id和page no查找对应的page是否有自适应哈希索引*/
ibool buf_page_peek_if_search_hashed(ulint space, ulint offset)
{
buf_block_t* block;
ibool is_hashed;
mutex_enter_fast(&(buf_pool->mutex));
block = buf_page_hash_get(space, offset);
if(block != NULL)
is_hashed = FALSE;
else
is_hashed = block->is_hashed;
mutex_exit(&(buf_pool->mutex));
return is_hashed;
}
/*判断space id与page no对应的page是否在buf pool上有缓冲*/
ibool buf_page_peek(ulint space, ulint offset)
{
if(buf_page_peek_block(space, offset))
return TRUE;
return FALSE;
}
/*设置block->file_page_was_freed为TRUE*/
buf_block_t* buf_page_set_file_page_was_freed(ulint space, ulint offset)
{
buf_block_t* block;
mutex_enter_fast(&(buf_pool->mutex));
block = buf_page_hash_get(space, offset);
if(block)
block->file_page_was_freed = TRUE;
mutex_exit(&(buf_pool->mutex));
return block;
}
/*设置block->file_page_was_freed为FALSE*/
buf_block_t* buf_page_reset_file_page_was_freed(ulint space, ulint offset)
{
buf_block_t* block;
mutex_enter_fast(&(buf_pool->mutex));
block = buf_page_hash_get(space, offset);
if (block)
block->file_page_was_freed = FALSE;
mutex_exit(&(buf_pool->mutex));
return(block);
}
/*通过space id和page no获得对应page在buf_pool中的frame地址，在这一过程可能会触发page从磁盘导入到buf_pool中*/
buf_frame_t* buf_page_get_gen(ulint space, ulint offset, ulint rw_latch, buf_frame_t* guess, ulint mode, char* file, ulint line, mtr_t* mtr)
{
buf_block_t* block;
ibool accessed;
ulint fix_type;
ibool success;
ibool must_read;
ut_ad(mtr);
ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH) || (rw_latch == RW_NO_LATCH));
ut_ad((mode != BUF_GET_NO_LATCH) || (rw_latch == RW_NO_LATCH));
ut_ad((mode == BUF_GET) || (mode == BUF_GET_IF_IN_POOL) || (mode == BUF_GET_NO_LATCH) || (mode == BUF_GET_NOWAIT));
buf_pool->n_page_gets ++;
loop:
mutex_enter_fast(&(buf_pool->mutex));
block = NULL;
if(guess){
block = buf_block_align(guess);
/*block和对应的space id和page no不匹配*/
if(offset != block->offset || space != block->space || block->state != BUF_BLOCK_FILE_PAGE)
block = NULL;
}
/*在buf_pool->hash_table中找*/
if(block == NULL)
block = buf_page_hash_get(space, offset);
/*page 不在缓冲池中*/
if(block == NULL){
mutex_exit(&(buf_pool->mutex));
if(mode == BUF_GET_IF_IN_POOL)
return NULL;
/*从磁盘上读入对应的页到buf pool中,这里会同步从磁盘中读取(space, offset)对应的页数据*/
buf_read_page(space, offset);
goto loop;
}
must_read = FALSE;
if(block->io_fix == BUF_IO_READ){ /*IO读操作*/
must_read = TRUE;
if(mode == BUF_GET_IF_IN_POOL){
mutex_exit(&(buf_pool->mutex));
return NULL;
}
}
buf_block_buf_fix_inc(block);
buf_block_make_young(block);
accessed = block->accessed;
block->accessed = TRUE;
mutex_exit(&(buf_pool->mutex));
ut_ad(block->buf_fix_count > 0);
ut_ad(block->state == BUF_BLOCK_FILE_PAGE);
/*对block上latch锁, FIX RULE规则*/
if(mode == BUF_GET_NOWAIT){
if(rw_latch == RW_S_LATCH){
success = rw_lock_s_lock_func_nowait(&(block->lock), file, line);
fix_type = MTR_MEMO_PAGE_S_FIX;
}
else{
ut_ad(rw_latch == RW_X_LATCH);
success = rw_lock_x_lock_func_nowait(&(block->lock), file, line);
fix_type = MTR_MEMO_PAGE_X_FIX;
}
/*上latch lock失败*/
if(!success){
mutex_enter(&(buf_pool->mutex));
block->buf_fix_count--;
mutex_exit(&(buf_pool->mutex));
return NULL;
}
}
else if(rw_latch == RW_NO_LATCH){
if (must_read) {
rw_lock_x_lock(&(block->read_lock));
rw_lock_x_unlock(&(block->read_lock));
}
fix_type = MTR_MEMO_BUF_FIX;
}
else if(rw_latch == RW_S_LATCH){
rw_lock_s_lock_func(&(block->lock), 0, file, line);
fix_type = MTR_MEMO_PAGE_S_FIX;
}
else{
rw_lock_x_lock_func(&(block->lock), 0, file, line);
fix_type = MTR_MEMO_PAGE_X_FIX;
}
mtr_memo_push(mtr, block, fix_type);
/*尝试线性预读，因为block是第一次读取到buffer pool中*/
if(!accessed)
buf_read_ahead_linear(space, offset);
return block->frame;
}
/*判断是否可以用乐观方式(当前page不从磁盘读取)访问一个page*/
ibool buf_page_optimistic_get_func(ulint rw_latch, buf_frame_t* guess, dulint modify_clock, char* file, ulint line, mtr_t* mtr)
{
buf_block_t* block;
ibool accessed;
ibool success;
ulint fix_type;
ut_ad(mtr && guess);
ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
buf_pool->n_page_gets ++;
block = buf_block_align(guess);
mutex_enter(&(buf_pool->mutex));
/*不是BLOK FILE PAGE*/
if(block->state != BUF_BLOCK_FILE_PAGE){
mutex_exit(&(buf_pool->mutex));
return FALSE;
}
buf_block_buf_fix_inc(block);
buf_block_make_young(block);
accessed = block->accessed;
block->accessed = TRUE;
ut_ad(!ibuf_inside() || ibuf_page(block->space, block->offset));
/*对block上latch锁*/
if (rw_latch == RW_S_LATCH) {
success = rw_lock_s_lock_func_nowait(&(block->lock), file, line);
fix_type = MTR_MEMO_PAGE_S_FIX;
} else {
success = rw_lock_x_lock_func_nowait(&(block->lock),file, line);
fix_type = MTR_MEMO_PAGE_X_FIX;
}
if(!success){
mutex_enter(&(buf_pool->mutex));
block->buf_fix_count --;
mutex_exit(&(buf_pool->mutex));
return FALSE;
}
/*modify_clock不匹配*/
if(!UT_DULINT_EQ(modify_clock, block->modify_clock)){
buf_page_dbg_add_level(block->frame, SYNC_NO_ORDER_CHECK);
/*释放持有的latch locker*/
if(rw_latch == RW_S_LATCH)
rw_lock_s_unlock(&(block->lock));
else
rw_lock_x_unlock(&(block->lock));
block->buf_fix_count --;
mutex_exit(&(buf_pool->mutex));
return FALSE;
}
mtr_memo_push(mtr, block, fix_type);
ut_ad(block->buf_fix_count > 0);
ut_ad(block->state == BUF_BLOCK_FILE_PAGE);
/*进行预读*/
if(!accessed)
buf_read_ahead_linear(buf_frame_get_space_id(guess), buf_frame_get_page_no(guess));
return TRUE;
}
/*判断是否可以用nowait方式访问一个已知的page*/
ibool buf_page_get_known_nowait(ulint rw_latch, buf_frame_t* guess, ulint mode, char* file, ulint line, mtr_t* mtr)
{
buf_block_t* block;
ibool success;
ulint fix_type;
ut_ad(mtr);
ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
buf_pool->n_page_gets ++;
block = buf_block_align(guess);
mutex_enter(&(buf_pool->mutex));
/*其他线程可能刚刚已经把这个buf block从LRU list中删除了,无法做到无等待访问page*/
if(block->state == BUF_BLOCK_REMOVE_HASH){
mutex_exit(&(buf_pool->mutex));
return FALSE;
}
/*fix_count复位是在mtr_commit的时候会调用buf_page_release做复位*/
buf_block_buf_fix_inc(block);
if(mode == BUF_MAKE_YOUNG)
buf_block_make_young(block);
mutex_exit(&(buf_pool->mutex));
ut_ad(!ibuf_inside() || mode == BUF_KEEP_OLD);
if (rw_latch == RW_S_LATCH) {
success = rw_lock_s_lock_func_nowait(&(block->lock), file, line);
fix_type = MTR_MEMO_PAGE_S_FIX;
} else {
success = rw_lock_x_lock_func_nowait(&(block->lock), file, line);
fix_type = MTR_MEMO_PAGE_X_FIX;
}
/*上锁失败*/
if(!success){
mutex_enter(&(buf_pool->mutex));
block->buf_fix_count--;
mutex_exit(&(buf_pool->mutex));
return FALSE;
}
mtr_memo_push(mtr, block, fix_type);
ut_ad(block->buf_fix_count > 0);
ut_ad(block->state == BUF_BLOCK_FILE_PAGE);
return TRUE;
}
/*为从ibbackup恢复page而进行的block初始化,在redo log做重演的时候调用*/
void buf_page_init_for_backup_restore(ulint space, ulint offset, buf_block_t* block)
{
/* Set the state of the block */
block->magic_n = BUF_BLOCK_MAGIC_N;
block->state = BUF_BLOCK_FILE_PAGE;
block->space = space;
block->offset = offset;
block->lock_hash_val = 0;
block->lock_mutex = NULL;
block->freed_page_clock = 0;
block->newest_modification = ut_dulint_zero;
block->oldest_modification = ut_dulint_zero;
block->accessed = FALSE;
block->buf_fix_count = 0;
block->io_fix = 0;
block->n_hash_helps = 0;
block->is_hashed = FALSE;
block->n_fields = 1;
block->n_bytes = 0;
block->side = BTR_SEARCH_LEFT_SIDE;
block->file_page_was_freed = FALSE;
}
/*初始化一个buffer pool page*/
static void buf_page_init(ulint space, ulint offset, buf_block_t* block)
{
ut_ad(mutex_own(&(buf_pool->mutex)));
ut_ad(block->state == BUF_BLOCK_READY_FOR_USE);
block->magic_n = BUF_BLOCK_MAGIC_N;
block->state = BUF_BLOCK_FILE_PAGE;
block->space = space;
block->offset = offset;
block->lock_hash_val = lock_rec_hash(space, offset);
block->lock_mutex = NULL;
/*将space page_no与block在page_hash中建立对应关系*/
HASH_INSERT(buf_block_t, hash, buf_pool->page_hash, buf_page_address_fold(space, offset), block);
block->freed_page_clock = 0;
block->newest_modification = ut_dulint_zero;
block->oldest_modification = ut_dulint_zero;
block->accessed = FALSE;
block->buf_fix_count = 0;
block->io_fix = 0;
block->n_hash_helps = 0;
block->is_hashed = FALSE;
block->n_fields = 1;
block->n_bytes = 0;
block->side = BTR_SEARCH_LEFT_SIDE;
block->file_page_was_freed = FALSE;
}
/************************************************************************
Function which inits a page for read to the buffer buf_pool. If the page is
already in buf_pool, does nothing. Sets the io_fix flag to BUF_IO_READ and
sets a non-recursive exclusive lock on the buffer frame. The io-handler must
take care that the flag is cleared and the lock released later. This is one
of the functions which perform the state transition NOT_USED => FILE_PAGE to
a block (the other is buf_page_create).
为从磁盘读取页数据的block做初始化。读取期间会持有block->lock的x-latch权限
**************************************************************************/
buf_block_t* buf_page_init_for_read(ulint mode, ulint space, ulint offset)
{
buf_block_t* block;
mtr_t mtr;
if(mode == BUF_READ_IBUF_PAGES_ONLY){
ut_ad(!ibuf_bitmap_page(offset));
ut_ad(ibuf_inside());
mtr_start(&mtr);
/*page不是ibuf的一个page,提交mini transction*/
if(!ibuf_page_low(space, offset, &mtr)){
mtr_commit(&mtr);
return NULL;
}
}
else
ut_ad(mode == BUF_READ_ANY_PAGE);
/*在buf pool上分配一个block*/
block = buf_block_alloc();
ut_ad(block);
mutex_enter(&(buf_pool->mutex));
/*在自适应hash索引上已经存在同样一个block,说明这个page已经在缓冲池中,直接释放返回*/
if(NULL != buf_page_hash_get(space, offset)){
mutex_exit(&(buf_pool->mutex));
buf_block_free(block);
if(mode == BUF_READ_IBUF_PAGES_ONLY)
mtr_commit(&mtr);
return NULL;
}
ut_ad(block);
/*对page对应的block进行初始化*/
buf_page_init(space, offset, block);
/*将block压入LRU List的old区域*/
buf_LRU_add_block(block, TRUE);
block->io_fix = BUF_IO_READ;
block->n_pend_reads ++;
/*在buf_page_io_complete时会将lock和read_lock释放*/
rw_lock_x_lock_gen(&(block->lock), BUF_IO_READ);
rw_lock_x_lock_gen(&(block->read_lock), BUF_IO_READ);
mutex_exit(&(buf_pool->mutex));
if(mode == BUF_READ_IBUF_PAGES_ONLY)
mtr_commit(&mtr);
return block;
}
/*建立一个page与buf_pool block之间的对应关系，并且会放入LRU队列中，通常这个过程是不需要从磁盘中导入页数据的，
一般是将block state有NO_USED-->FILE_PAGE,很有可能是写需要新的page*/
buf_frame_t* buf_page_create(ulint space, ulint offset, mtr_t* mtr)
{
buf_frame_t* frame;
buf_block_t* block;
buf_block_t* free_block = NULL;
ut_ad(mtr);
free_block = buf_LRU_get_free_block();
/*进行ibuf中数据记录的删除,只是个初始化过程，不是一个从磁盘导入页数据的过程
Delete possible entries for the page from the insert buffer:
such can exist if the page belonged to an index which was dropped*/
ibuf_merge_or_delete_for_page(NULL, space, offset);
mutex_enter(&(buf_pool->mutex));
block = buf_page_hash_get(space, offset);
if(block != NULL){
block->file_page_was_freed = FALSE;
mutex_exit(&(buf_pool->mutex));
buf_block_free(block);
/*数据页已经在buf pool当中，直接返回frame对象*/
frame = buf_page_get_with_no_latch(space, offset, mtr);
return frame;
}
if(buf_debug_prints)
printf("Creating space %lu page %lu to buffer\n", space, offset);
block = free_block;
/*初始化page与block隐射关系，并加入到LRU中*/
buf_page_init(space, offset, block);
buf_LRU_add_block(block, FALSE);
buf_block_buf_fix_inc(block);
/*在mtr_commit时指定其调用buf_page_release,表明调用者完成对页的操作*/
mtr_memo_push(mtr, block, MTR_MEMO_BUF_FIX);
block->accessed = TRUE;
buf_pool->n_pages_created ++;
mutex_exit(&(buf_pool->mutex));
frame = block->frame;
return frame;
}
/*从磁盘上读或者写一个页数据完成*/
void buf_page_io_complete(buf_block_t* block)
{
dict_index_t* index;
dulint id;
ulint io_type;
ulint read_page_no;
ut_ad(block);
io_type = block->io_fix;
if(io_type == BUF_IO_READ){
read_page_no = mach_read_from_4(block->frame + FIL_PAGE_OFFSET);
if(read_page_no != 0 && trx_doublewrite_age_inside(read_page_no) && read_page_no != block->offset){
fprintf(stderr,"InnoDB: Error: page n:o stored in the page read in is %lu, should be %lu!\n",
read_page_no, block->offset);
}
/*判断页是否完整*/
if(buf_page_is_corrupted(block->frame)){
fprintf(stderr,
"InnoDB: Database page corruption on disk or a failed\n"
"InnoDB: file read of page %lu.\n", block->offset);
fprintf(stderr, "InnoDB: You may have to recover from a backup.\n");
buf_page_print(block->frame);
fprintf(stderr, "InnoDB: Database page corruption on disk or a failed\n"
"InnoDB: file read of page %lu.\n", block->offset);
fprintf(stderr, "InnoDB: You may have to recover from a backup.\n");
fprintf(stderr,
"InnoDB: It is also possible that your operating\n"
"InnoDB: system has corrupted its own file cache\n"
"InnoDB: and rebooting your computer removes the\n"
"InnoDB: error.\n"
"InnoDB: If the corrupt page is an index page\n"
"InnoDB: you can also try to fix the corruption\n"
"InnoDB: by dumping, dropping, and reimporting\n"
"InnoDB: the corrupt table. You can use CHECK\n"
"InnoDB: TABLE to scan your table for corruption.\n"
"InnoDB: Look also at section 6.1 of\n"
"InnoDB: http://www.innodb.com/ibman.html about\n"
"InnoDB: forcing recovery.\n");
if(srv_force_recovery < SRV_FORCE_IGNORE_CORRUPT){
fprintf(stderr, "InnoDB: Ending processing because of a corrupt database page.\n");
exit(1);
}
}
/*正在redo log恢复过程*/
if(recv_recovery_is_on())
recv_recover_page(FALSE, TRUE, block->frame, block->space, block->offset);
/*进行ibuf中的记录合并*/
if(!recv_no_ibuf_operations)
ibuf_merge_or_delete_for_page(block->frame, block->space, block->offset);
}
mutex_enter(&(buf_pool->mutex));
/*更新block与buf_pool的计数状态*/
block->io_fix = 0;
if(io_type == BUF_IO_READ){
ut_ad(buf_pool->n_pend_reads > 0);
buf_pool->n_pend_reads--;
buf_pool->n_pages_read++;
/*在发起读的时候进行也lock*/
rw_lock_x_unlock_gen(&(block->lock), BUF_IO_READ);
rw_lock_x_unlock_gen(&(block->read_lock), BUF_IO_READ);
if(buf_debug_prints)
printf("Has read ");
}
else{
ut_ad(io_type == BUF_IO_WRITE);
/*page磁盘写完成*/
buf_flush_write_complete(block);
rw_lock_s_unlock_gen(&(block->lock), BUF_IO_WRITE);
buf_pool->n_pages_written ++;
if(buf_debug_prints)
printf("Has written ");
}
mutex_exit(&(buf_pool->mutex));
if (buf_debug_prints) {
printf("page space %lu page no %lu", block->space, block->offset);
id = btr_page_get_index_id(block->frame);
index = NULL;
printf("\n");
}
}
void buf_pool_invalidate(void)
{
ibool freed;
ut_ad(buf_all_freed());
freed = TRUE;
while (freed)
freed = buf_LRU_search_and_free_block(0);
mutex_enter(&(buf_pool->mutex));
ut_ad(UT_LIST_GET_LEN(buf_pool->LRU) == 0);
mutex_exit(&(buf_pool->mutex));
}
ibool buf_validate(void)
{
buf_block_t* block;
ulint i;
ulint n_single_flush = 0;
ulint n_lru_flush = 0;
ulint n_list_flush = 0;
ulint n_lru = 0;
ulint n_flush = 0;
ulint n_free = 0;
ulint n_page = 0;
ut_ad(buf_pool);
mutex_enter(&(buf_pool->mutex));
for (i = 0; i < buf_pool->curr_size; i++) {
block = buf_pool_get_nth_block(buf_pool, i);
if (block->state == BUF_BLOCK_FILE_PAGE) {
ut_a(buf_page_hash_get(block->space, block->offset) == block);
n_page++;
if (block->io_fix == BUF_IO_WRITE) {
if (block->flush_type == BUF_FLUSH_LRU){
n_lru_flush++;
ut_a(rw_lock_is_locked(&(block->lock), RW_LOCK_SHARED));
}
else if (block->flush_type == BUF_FLUSH_LIST)
n_list_flush++;
else if (block->flush_type == BUF_FLUSH_SINGLE_PAGE)
n_single_flush++;
else
ut_error;
}
else if (block->io_fix == BUF_IO_READ)
ut_a(rw_lock_is_locked(&(block->lock), RW_LOCK_EX));
n_lru++;
if (ut_dulint_cmp(block->oldest_modification, ut_dulint_zero) > 0)
n_flush++;
} else if (block->state == BUF_BLOCK_NOT_USED) {
n_free++;
}
}
if (n_lru + n_free > buf_pool->curr_size) {
printf("n LRU %lu, n free %lu\n", n_lru, n_free);
ut_error;
}
ut_a(UT_LIST_GET_LEN(buf_pool->LRU) == n_lru);
if (UT_LIST_GET_LEN(buf_pool->free) != n_free) {
printf("Free list len %lu, free blocks %lu\n", UT_LIST_GET_LEN(buf_pool->free), n_free);
ut_error;
}
ut_a(UT_LIST_GET_LEN(buf_pool->flush_list) == n_flush);
ut_a(buf_pool->n_flush[BUF_FLUSH_SINGLE_PAGE] == n_single_flush);
ut_a(buf_pool->n_flush[BUF_FLUSH_LIST] == n_list_flush);
ut_a(buf_pool->n_flush[BUF_FLUSH_LRU] == n_lru_flush);
mutex_exit(&(buf_pool->mutex));
ut_a(buf_LRU_validate());
ut_a(buf_flush_validate());
return(TRUE);
}
void buf_print(void)
{
dulint* index_ids;
ulint* counts;
ulint size;
ulint i;
ulint j;
dulint id;
ulint n_found;
buf_frame_t* frame;
dict_index_t* index;
ut_ad(buf_pool);
size = buf_pool_get_curr_size() / UNIV_PAGE_SIZE;
index_ids = mem_alloc(sizeof(dulint) * size);
counts = mem_alloc(sizeof(ulint) * size);
mutex_enter(&(buf_pool->mutex));
printf("buf_pool size %lu \n", size);
printf("database pages %lu \n", UT_LIST_GET_LEN(buf_pool->LRU));
printf("free pages %lu \n", UT_LIST_GET_LEN(buf_pool->free));
printf("modified database pages %lu \n", UT_LIST_GET_LEN(buf_pool->flush_list));
printf("n pending reads %lu \n", buf_pool->n_pend_reads);
printf("n pending flush LRU %lu list %lu single page %lu\n",
buf_pool->n_flush[BUF_FLUSH_LRU],
buf_pool->n_flush[BUF_FLUSH_LIST], buf_pool->n_flush[BUF_FLUSH_SINGLE_PAGE]);
printf("pages read %lu, created %lu, written %lu\n",
buf_pool->n_pages_read, buf_pool->n_pages_created, buf_pool->n_pages_written);
/* Count the number of blocks belonging to each index in the buffer */
n_found = 0;
for (i = 0 ; i < size; i++)
counts[i] = 0;
for (i = 0; i < size; i++) {
frame = buf_pool_get_nth_block(buf_pool, i)->frame;
if (fil_page_get_type(frame) == FIL_PAGE_INDEX) {
id = btr_page_get_index_id(frame);
/* Look for the id in the index_ids array */
j = 0;
while (j < n_found){
if (ut_dulint_cmp(index_ids[j], id) == 0){
(counts[j])++;
break;
}
j++;
}
if (j == n_found) {
n_found++;
index_ids[j] = id;
counts[j] = 1;
}
}
}
mutex_exit(&(buf_pool->mutex));
for (i = 0; i < n_found; i++) {
index = dict_index_get_if_in_cache(index_ids[i]);