pobj_layout_begin(3)

1POBJ_LAYOUT_BEGIN(3)       PMDK Programmer's Manual       POBJ_LAYOUT_BEGIN(3)
2
3
4

NAME

6       POBJ_LAYOUT_BEGIN(),  POBJ_LAYOUT_TOID(), POBJ_LAYOUT_ROOT(), POBJ_LAY‐
7       OUT_NAME(),  POBJ_LAYOUT_END(),  POBJ_LAYOUT_TYPES_NUM()  -  persistent
8       memory transactional object store layout
9

SYNOPSIS

11              #include <libpmemobj.h>
12
13              POBJ_LAYOUT_BEGIN(layout)
14              POBJ_LAYOUT_TOID(layout, TYPE)
15              POBJ_LAYOUT_ROOT(layout, ROOT_TYPE)
16              POBJ_LAYOUT_NAME(layout)
17              POBJ_LAYOUT_END(layout)
18              POBJ_LAYOUT_TYPES_NUM(layout)
19

DESCRIPTION

21       libpmemobj(7)  defines  a set of macros for convenient declaration of a
22       pool's layout.  The layout declaration consists of  declarations  of  a
23       number  of used types.  The declared types will be assigned consecutive
24       type numbers.  Declared types may be  used  in  conjunction  with  type
25       safety macros (see TOID_DECLARE(3)).  Once created, the layout declara‐
26       tion must not be changed unless any new types are added at the  end  of
27       the  existing  layout  declaration.  Modifying any existing declaration
28       may lead to changes in the type numbers of  declared  types,  which  in
29       consequence may cause data corruption.
30
31       The  POBJ_LAYOUT_BEGIN() macro indicates a begin of declaration of lay‐
32       out.  The LAYOUT argument is a name of layout.  This argument  must  be
33       passed to all macros related to the declaration of layout.
34
35       The  POBJ_LAYOUT_TOID()  macro  declares a typed OID for type passed as
36       TYPE argument inside the declaration of layout.  All types declared us‐
37       ing  this macro are assigned with consecutive type numbers.  This macro
38       must be used  between  the  POBJ_LAYOUT_BEGIN()  and  POBJ_LAYOUT_END()
39       macros, with the same name passed as LAYOUT argument.
40
41       The  POBJ_LAYOUT_ROOT()  macro  declares a typed OID for type passed as
42       ROOT_TYPE argument inside the declaration of  layout.   The  typed  OID
43       will be assigned with type number for root object POBJ_ROOT_TYPE_NUM.
44
45       The POBJ_LAYOUT_END() macro ends the declaration of layout.
46
47       The  POBJ_LAYOUT_NAME() macro returns the name of layout as a null-ter‐
48       minated string.
49
50       The POBJ_LAYOUT_TYPES_NUM() macro returns number of types declared  us‐
51       ing the POBJ_LAYOUT_TOID() macro within the layout declaration.
52

EXAMPLE

54       This is an example of layout declaration:
55
56              POBJ_LAYOUT_BEGIN(mylayout);
57              POBJ_LAYOUT_ROOT(mylayout, struct root);
58              POBJ_LAYOUT_TOID(mylayout, struct node);
59              POBJ_LAYOUT_TOID(mylayout, struct foo);
60              POBJ_LAYOUT_END(mylayout);
61
62              struct root
63              {
64                  TOID(struct node) node;
65              };
66
67              struct node
68              {
69                  TOID(struct node) next;
70                  TOID(struct foo) foo;
71              };
72
73       The  name  of  layout and the number of declared types can be retrieved
74       using the following code:
75
76              const char *layout_name = POBJ_LAYOUT_NAME(mylayout);
77              int num_of_types = POBJ_LAYOUT_TYPES_NUM(mylayout);
78

NAME

SYNOPSIS

DESCRIPTION

EXAMPLE

SEE ALSO