Man page - d_ro(3)

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Package: libpmemobj-dev
apt-get install libpmemobj-dev

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libpmemobj-dev

Manual

NAME

TOID_DECLARE (), TOID_DECLARE_ROOT (), TOID (), TOID_TYPE_NUM (), TOID_TYPE_NUM_OF (), TOID_VALID (), OID_INSTANCEOF (), TOID_ASSIGN (), TOID_IS_NULL (), TOID_EQUALS (), TOID_TYPEOF (), TOID_OFFSETOF (), DIRECT_RW (), D_RW (), DIRECT_RO (), D_RO () - libpmemobj type safety mechanism

SYNOPSIS

#include <libpmemobj.h>


TOID_DECLARE(TYPE, uint64_t type_num)
TOID_DECLARE_ROOT(ROOT_TYPE)
TOID(TYPE)
TOID_TYPE_NUM(TYPE)
TOID_TYPE_NUM_OF(TOID oid)
TOID_VALID(TOID oid)
OID_INSTANCEOF(PMEMoid oid, TYPE)
TOID_ASSIGN(TOID o, VALUE)
TOID_IS_NULL(TOID o)
TOID_EQUALS(TOID lhs, TOID rhs)
TOID_TYPEOF(TOID o)
TOID_OFFSETOF(TOID o, FILED)
DIRECT_RW(TOID oid)
D_RW(TOID oid)
DIRECT_RO(TOID oid)
D_RO(TOID oid)

DESCRIPTION

Operating on untyped object handles, as well as on direct untyped object pointers ( void* ), may be confusing and error-prone. To facilitate type safety, libpmemobj (7) defines a set of macros that provide static type enforcement, catching potential errors at compile time. For example, a compile-time error is generated when an attempt is made to assign a handle to an object of one type to the object handle variable of another type of object.

The TOID_DECLARE () macro declares a typed OID of user-defined type TYPE and type number type_num .

The TOID_DECLARE_ROOT () macro declares a typed OID of user-defined type ROOT_TYPE and root object type number POBJ_ROOT_TYPE_NUM .

The TOID () macro declares a handle to an object of type TYPE , where TYPE is the name of a user-defined structure. The typed OID must be declared first using the TOID_DECLARE (), TOID_DECLARE_ROOT (), POBJ_LAYOUT_TOID (3) or POBJ_LAYOUT_ROOT (3) macros.

The TOID_TYPE_NUM () macro returns the type number of the type specified by TYPE .

The TOID_TYPE_NUM_OF () macro returns the type number of the object specified by oid . The type number is read from the typed OID .

The TOID_VALID () macro validates whether the type number stored in the object’s metadata is equal to the type number read from the typed OID .

The OID_INSTANCEOF () macro checks whether the oid is of type TYPE .

The TOID_ASSIGN () macro assigns the object handle VALUE to typed OID o .

The TOID_IS_NULL () macro evaluates to true if the object handle represented by o is OID_NULL .

The TOID_EQUALS () macro evaluates to true if both the lhs and rhs object handles reference the same persistent object.

The TOID_TYPEOF () macro returns the type of the object handle represented by typed OID o .

The TOID_OFFSETOF () macro returns the offset of the FIELD member from the start of the object represented by o .

The DIRECT_RW () macro and its shortened form D_RW () return a typed write pointer ( TYPE* ) to an object represented by oid . If oid is OID_NULL , the macro evaluates to NULL.