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
|
/******************************************************
Cursor read
(c) 1997 Innobase Oy
Created 2/16/1997 Heikki Tuuri
*******************************************************/
#ifndef read0read_h
#define read0read_h
#include "univ.i"
#include "ut0byte.h"
#include "ut0lst.h"
#include "trx0trx.h"
#include "read0types.h"
/*************************************************************************
Opens a read view where exactly the transactions serialized before this
point in time are seen in the view. */
read_view_t*
read_view_open_now(
/*===============*/
/* out, own: read view struct */
dulint cr_trx_id, /* in: trx_id of creating
transaction, or (0, 0) used in
purge */
mem_heap_t* heap); /* in: memory heap from which
allocated */
/*************************************************************************
Makes a copy of the oldest existing read view, or opens a new. The view
must be closed with ..._close. */
read_view_t*
read_view_oldest_copy_or_open_new(
/*==============================*/
/* out, own: read view struct */
dulint cr_trx_id, /* in: trx_id of creating
transaction, or (0, 0) used in
purge */
mem_heap_t* heap); /* in: memory heap from which
allocated */
/*************************************************************************
Closes a read view. */
void
read_view_close(
/*============*/
read_view_t* view); /* in: read view */
/*************************************************************************
Closes a consistent read view for MySQL. This function is called at an SQL
statement end if the trx isolation level is <= TRX_ISO_READ_COMMITTED. */
void
read_view_close_for_mysql(
/*======================*/
trx_t* trx); /* in: trx which has a read view */
/*************************************************************************
Checks if a read view sees the specified transaction. */
UNIV_INLINE
ibool
read_view_sees_trx_id(
/*==================*/
/* out: TRUE if sees */
read_view_t* view, /* in: read view */
dulint trx_id);/* in: trx id */
/*************************************************************************
Prints a read view to stderr. */
void
read_view_print(
/*============*/
read_view_t* view); /* in: read view */
/*************************************************************************
Create a consistent cursor view for mysql to be used in cursors. In this
consistent read view modifications done by the creating transaction or future
transactions are not visible. */
cursor_view_t*
read_cursor_view_create_for_mysql(
/*==============================*/
trx_t* cr_trx);/* in: trx where cursor view is created */
/*************************************************************************
Close a given consistent cursor view for mysql and restore global read view
back to a transaction read view. */
void
read_cursor_view_close_for_mysql(
/*=============================*/
trx_t* trx, /* in: trx */
cursor_view_t* curview); /* in: cursor view to be closed */
/*************************************************************************
This function sets a given consistent cursor view to a transaction
read view if given consistent cursor view is not NULL. Otherwise, function
restores a global read view to a transaction read view. */
void
read_cursor_set_for_mysql(
/*======================*/
trx_t* trx, /* in: transaction where cursor is set */
cursor_view_t* curview);/* in: consistent cursor view to be set */
/* Read view lists the trx ids of those transactions for which a consistent
read should not see the modifications to the database. */
struct read_view_struct{
ulint type; /* VIEW_NORMAL, VIEW_HIGH_GRANULARITY */
dulint undo_no; /* (0, 0) or if type is VIEW_HIGH_GRANULARITY
transaction undo_no when this high-granularity
consistent read view was created */
ibool can_be_too_old; /* TRUE if the system has had to purge old
versions which this read view should be able
to access: the read view can bump into the
DB_MISSING_HISTORY error */
dulint low_limit_no; /* The view does not need to see the undo
logs for transactions whose transaction number
is strictly smaller (<) than this value: they
can be removed in purge if not needed by other
views */
dulint low_limit_id; /* The read should not see any transaction
with trx id >= this value */
dulint up_limit_id; /* The read should see all trx ids which
are strictly smaller (<) than this value */
ulint n_trx_ids; /* Number of cells in the trx_ids array */
dulint* trx_ids; /* Additional trx ids which the read should
not see: typically, these are the active
transactions at the time when the read is
serialized, except the reading transaction
itself; the trx ids in this array are in a
descending order */
dulint creator_trx_id; /* trx id of creating transaction, or
(0, 0) used in purge */
UT_LIST_NODE_T(read_view_t) view_list;
/* List of read views in trx_sys */
};
/* Read view types */
#define VIEW_NORMAL 1 /* Normal consistent read view
where transaction does not see changes
made by active transactions except
creating transaction. */
#define VIEW_HIGH_GRANULARITY 2 /* High-granularity read view where
transaction does not see changes
made by active transactions and own
changes after a point in time when this
read view was created. */
/* Implement InnoDB framework to support consistent read views in
cursors. This struct holds both heap where consistent read view
is allocated and pointer to a read view. */
struct cursor_view_struct{
mem_heap_t* heap;
/* Memory heap for the cursor view */
read_view_t* read_view;
/* Consistent read view of the cursor*/
ulint n_mysql_tables_in_use;
/* number of Innobase tables used in the
processing of this cursor */
};
#ifndef UNIV_NONINL
#include "read0read.ic"
#endif
#endif
|