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.\" by Jason R. Thorpe
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.Dd June 16, 2018
.Dt SPECIFICDATA 9
.Os
.Sh NAME
.Nm specificdata ,
.Nm specificdata_domain_create ,
.Nm specificdata_domain_delete ,
.Nm specificdata_key_create ,
.Nm specificdata_key_delete ,
.Nm specificdata_init ,
.Nm specificdata_fini ,
.Nm specificdata_getspecific ,
.Nm specificdata_getspecific_unlocked ,
.Nm specificdata_setspecific ,
.Nm specificdata_setspecific_nowait
.Nd manipulate arbitrary data attached to objects
.Sh SYNOPSIS
.In sys/specificdata.h
.Ft specificdata_domain_t
.Fn specificdata_domain_create
.Ft void
.Fn specificdata_domain_delete "specificdata_domain_t sd"
.Ft int
.Fn specificdata_key_create "specificdata_domain_t sd" \
"specificdata_key_t *keyp" "specificdata_dtor_t dtor"
.Ft void
.Fn specificdata_key_delete "specificdata_domain_t sd" "specificdata_key_t key"
.Ft int
.Fn specificdata_init "specificdata_domain_t sd" "specificdata_reference *ref"
.Ft void
.Fn specificdata_fini "specificdata_domain_t sd" "specificdata_reference *ref"
.Ft "void *"
.Fn specificdata_getspecific "specificdata_domain_t sd" \
"specificdata_reference *ref" "specificdata_key_t key"
.Ft "void *"
.Fn specificdata_getspecific_unlocked "specificdata_domain_t sd" \
"specificdata_reference *ref" "specificdata_key_t key"
.Ft void
.Fn specificdata_setspecific "specificdata_domain_t sd" \
"specificdata_reference *ref" "specificdata_key_t key" "void *data"
.Ft int
.Fn specificdata_setspecific_nowait "specificdata_domain_t sd" \
"specificdata_reference *ref" "specificdata_key_t key" "void *data"
.Sh DESCRIPTION
The
.Nm
facility provides a mechanism for storing arbitrary data, identified by
an index key, within containers which exist within the objects associated
with a particular domain.
.Sh FUNCTIONS
.Bl -tag -width abcd
.It Fn specificdata_domain_create
Create and initialize a new domain.
.It Fn specificdata_domain_delete sd
Deletes domain
.Fa sd .
.It Fn specificdata_key_create sd keyp dtor
Create a new key for
.Fa sd .
If the
.Fa dtor
argument is not
.Dv NULL ,
it specifies a destructor which will be called when a datum associated
with the specified key is deleted from a container within the
.Fa sd .
The unique identifier of the created key is returned in
.Fa keyp .
.It Fn specificdata_key_delete sd key
Delete a key for
.Fa sd ,
and delete any associated data from all containers within the domain.
.It Fn specificdata_init sd ref
Initialize the container
.Fa ref
for use in
.Fa sd .
.It Fn specificdata_fini sd ref
Destroy the container
.Fa ref ,
and destroy all of the data stuffed into the container.
.It Fn specificdata_getspecific sd ref key
Retrieve the datum from the container
.Fa ref
associated with
.Fa key .
.It Fn specificdata_getspecific_unlocked sd ref key
Retrieve the datum from the container
.Fa ref
associated with
.Fa key
in a lockless manner.
Care must be taken to ensure that no other thread could cause
.Fa ref
to become invalid (i.e. point at the wrong container) by issuing a
.Fn setspecific
call or by destroying the container.
.It Fn specificdata_setspecific sd ref key data
Store
.Fa data
in the container
.Fa ref
and associate it with
.Fa key .
If a datum has previously been stored, the new value replaces the original;
the original value is not destroyed, i.e. its destructor is not invoked.
Note that there is no provision for removing a datum without replacing it.
.It Fn specificdata_setspecific_nowait sd ref key data
(Unimplemented)
.El
.Sh CODE REFERENCES
The
.Nm
functionality is implemented in
.Pa sys/kern/subr_specificdata.c .
.Pp
The header file
.In sys/sys/specificdata.h
describes the public interface.
.Sh HISTORY
The
.Nm
subsystem first appeared in
.Nx 4.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
subsystem was written by
.An Jason Thorpe Aq Mt thorpej@NetBSD.org .
This manual page was written by
.An Paul Goyette Aq Mt pgoyette@NetBSD.org .