pthread.pod

Linux下的中文输入法

The I<guardsize> attribute is provided to the application
for two reasons:

=over 4

=item 1.

Overflow protection can potentially result in wasted system resources.
An application that creates a large number of threads, and which knows
its threads will never overflow their stack, can save system resources
by turning off guard areas.

=item 2.

When threads allocate large data structures on the stack,
large guard areas may be needed to detect stack overflow.

=back

The I<pthread_attr_getguardsize()> function gets the I<guardsize>
attribute in the I<attr> object. This attribute is returned in the
I<guardsize> parameter.

The I<pthread_attr_setguardsize()> function sets the I<guardsize>
attribute in the I<attr> object. The new value of this attribute is
obtained from the I<guardsize> parameter. If I<guardsize> is zero,
a guard area will not be provided for threads created with I<attr>.
If I<guardsize> is greater than zero, a guard area of at least size
I<guardsize> bytes is provided for each thread created with I<attr>.

A conforming implementation is permitted to round up the value
contained in I<guardsize> to a multiple of the configurable system
variable PAGESIZE (see I<<sys/mman.h>>). If an implementation rounds
up the value of I<guardsize> to a multiple of PAGESIZE, a call to
I<pthread_attr_getguardsize()> specifying I<attr> will store in the
I<guardsize> parameter the guard size specified by the previous
I<pthread_attr_setguardsize()> function call.

The default value of the I<guardsize> attribute is PAGESIZE bytes. The
actual value of PAGESIZE is implementation-dependent and may not be the
same on all implementations.

If the I<stackaddr> attribute has been set (that is, the caller is
allocating and managing its own thread stacks), the I<guardsize>
attribute is ignored and no protection will be provided by the
implementation. It is the responsibility of the application to manage
stack overflow along with stack allocation and management in this case.

=head1 RETURN VALUE

If successful, the I<pthread_attr_getguardsize()> and
I<pthread_attr_setguardsize()> functions return zero. Otherwise, an
error number is returned to indicate the error.

=head1 ERRORS

The I<pthread_attr_getguardsize()> and I<pthread_attr_setguardsize()>
functions will fail if:

=over 4

=item [EINVAL]

The attribute I<attr> is invalid.

=item [EINVAL]

The parameter I<guardsize> is invalid.

=item [EINVAL]

The parameter I<guardsize> contains an invalid value.

=back

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

None.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<<pthread.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setinheritsched,> B<pthread_attr_getinheritsched>
- set and get inheritsched attribute
(B<REALTIME THREADS>)

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setinheritsched(pthread_attr_t *I<attr>,
int I<inheritsched>);
int pthread_attr_getinheritsched(const pthread_attr_t *I<attr>,
int *I<inheritsched>);

=head1 DESCRIPTION

The functions I<pthread_attr_setinheritsched()> and
I<pthread_attr_getinheritsched()>, respectively, set and get the
I<inheritsched> attribute in the I<attr> argument.

When the attribute objects are used by I<pthread_create()>, the
I<inheritsched> attribute determines how the other scheduling attributes
of the created thread are to be set:

=over 4

=item PTHREAD_INHERIT_SCHED

Specifies that the scheduling policy and associated attributes are to
be inherited from the creating thread, and the scheduling attributes in
this I<attr> argument are to be ignored.

=item PTHREAD_EXPLICIT_SCHED

Specifies that the scheduling policy and associated attributes
are to be set to the corresponding values from this attribute object.

=back

The symbols PTHREAD_INHERIT_SCHED and PTHREAD_EXPLICIT_SCHED are defined
in the header I<<pthread.h>>.

=head1 RETURN VALUE

If successful, the I<pthread_attr_setinheritsched()> and
I<pthread_attr_getinheritsched()> functions return zero. Otherwise, an
error number is returned to indicate the error.

=head1 ERRORS

The I<pthread_attr_setinheritsched()> and
I<pthread_attr_getinheritsched()> functions will fail if:

=over 4

=item [ENOSYS]

The option _POSIX_THREAD_PRIORITY_SCHEDULING is not defined and the
implementation does not support the function.

=back

The I<pthread_attr_setinheritsched()> function may fail if:

=over 4

=item [EINVAL]

The value of the attribute being set is not valid.

=item [ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

=back

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

After these attributes have been set, a thread can be created with the
specified attributes using I<pthread_create()>. Using these routines
does not affect the current running thread.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<pthread_attr_init()>,
I<pthread_attr_setscope()>,
I<pthread_attr_setschedpolicy()>,
I<pthread_attr_setschedparam()>,
I<pthread_create()>,
I<<pthread.h>>,
I<pthread_setschedparam()>,
I<<sched.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setschedparam,> B<pthread_attr_getschedparam>
- set and get schedparam attribute

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setschedparam(pthread_attr_t *I<attr>, const struct sched_param *I<param>);

int pthread_attr_getschedparam(const pthread_attr_t *I<attr>, struct sched_param *I<param>);

=head1 DESCRIPTION

The functions I<pthread_attr_setschedparam()> and
I<pthread_attr_getschedparam()>, respectively, set and get the
scheduling parameter attributes in the I<attr> argument. The contents of
the I<param> structure are defined in I<<sched.h>>. For the SCHED_FIFO
and SCHED_RR policies, the only required member of I<param> is
I<sched_priority>.

=head1 RETURN VALUE

If successful, the I<pthread_attr_setschedparam()> and
I<pthread_attr_getschedparam()> functions return zero. Otherwise, an
error number is returned to indicate the error.

=head1 ERRORS

The I<pthread_attr_setschedparam()> function may fail if:

=over 4

=item [EINVAL]

The value of the attribute being set is not valid.

=item [ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

=back

The
I<pthread_attr_setschedparam()>
and
I<pthread_attr_getschedparam()>
functions will not return an error code of [EINTR].

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

After these attributes have been set, a thread can be created with the
specified attributes using I<pthread_create()>. Using these routines
does not affect the current running thread.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<pthread_attr_init()>,
I<pthread_attr_setscope()>,
I<pthread_attr_setinheritsched()>,
I<pthread_attr_setschedpolicy()>,
I<pthread_create()>,
I<<pthread.h>>,
I<pthread_setschedparam()>,
I<<sched.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setschedpolicy,> B<pthread_attr_getschedpolicy>
- set and get schedpolicy attribute
(B<REALTIME THREADS>)

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setschedpolicy(pthread_attr_t *I<attr>, int I<policy>);
int pthread_attr_getschedpolicy(const pthread_attr_t *I<attr>,
int *I<policy>);

=head1 DESCRIPTION

The functions I<pthread_attr_setschedpolicy()> and
I<pthread_attr_getschedpolicy()>, respectively, set and get the
I<schedpolicy> attribute in the I<attr> argument.

The supported values of I<policy> include SCHED_FIFO, SCHED_RR and
SCHED_OTHER, which are defined by the header I<<sched.h>>. When threads
executing with the scheduling policy SCHED_FIFO or SCHED_RR are waiting
on a mutex, they acquire the mutex in priority order when the mutex is
unlocked.

=head1 RETURN VALUE

If successful, the I<pthread_attr_setschedpolicy()> and
I<pthread_attr_getschedpolicy()> functions return zero. Otherwise, an
error number is returned to indicate the error.

=head1 ERRORS

The I<pthread_attr_setschedpolicy()> and
I<pthread_attr_getschedpolicy()> functions will fail if:

=over 4

=item [ENOSYS]

The option _POSIX_THREAD_PRIORITY_SCHEDULING is not defined and the
implementation does not support the function.

=back

The I<pthread_attr_setschedpolicy()> function may fail if:

=over 4

=item [EINVAL]

The value of the attribute being set is not valid.

=item [ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

=back

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

After these attributes have been set, a thread can be created with the
specified attributes using I<pthread_create()>. Using these routines
does not affect the current running thread.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<pthread_attr_init()>,
I<pthread_attr_setscope()>,
I<pthread_attr_setinheritsched()>,
I<pthread_attr_setschedparam()>,
I<pthread_create()>,
I<<pthread.h>>,
I<pthread_setschedparam()>,
I<<sched.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setscope,> B<pthread_attr_getscope>
- set and get contentionscope attribute
(B<REALTIME THREADS>)

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setscope(pthread_attr_t *I<attr>, int I<contentionscope>);
int pthread_attr_getscope(const pthread_attr_t *I<attr>,
int *I<contentionscope>);

=head1 DESCRIPTION

The I<pthread_attr_setscope()> and I<pthread_attr_getscope()> functions
are used to set and get the I<contentionscope> attribute in the I<attr>
object.

The I<contentionscope> attribute may have the values
PTHREAD_SCOPE_SYSTEM, signifying system scheduling contention scope, or
PTHREAD_SCOPE_PROCESS, signifying process scheduling contention scope.
The symbols PTHREAD_SCOPE_SYSTEM and PTHREAD_SCOPE_PROCESS are defined
by the header I<<pthread.h>>.

=head1 RETURN VALUE

If successful, the I<pthread_attr_setscope()> and
I<pthread_attr_getscope()> functions return zero. Otherwise, an error
number is returned to indicate the error.

=head1 ERRORS

The I<pthread_attr_setscope()> and I<pthread_attr_getscope()> functions
will fail if:

=over 4

=item [ENOSYS]

The option _POSIX_THREAD_PRIORITY_SCHEDULING is not defined and the
implementation does not support the function.

=back

The
I<pthread_attr_setscope()>,
function may fail if:

=over 4

=item [EINVAL]

The value of the attribute being set is not valid.

=item [ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

=back

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

After these attributes have been set, a thread can be created with the
specified attributes using I<pthread_create()>. Using these routines
does not affect the current running thread.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<pthread_attr_init()>,
I<pthread_attr_setinheritsched()>,
I<pthread_attr_setschedpolicy()>,
I<pthread_attr_setschedparam()>,
I<pthread_create()>,
I<<pthread.h>>,
I<pthread_setschedparam()>,
I<<sched.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setstackaddr,> B<pthread_attr_getstackaddr>
- set and get stackaddr attribute

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setstackaddr(pthread_attr_t *I<attr>, void *I<stackaddr>);

int pthread_attr_getstackaddr(const pthread_attr_t *I<attr>, void **I<stackaddr>);

=head1 DESCRIPTION

The functions I<pthread_attr_setstackaddr()> and
I<pthread_attr_getstackaddr()>, respectively, set and get the thread
creation I<stackaddr> attribute in the I<attr> object.

The I<stackaddr> attribute specifies the location of storage to be used
for the created thread's stack. The size of the storage is at least
PTHREAD_STACK_MIN.

=head1 RETURN VALUE

Upon successful completion, I<pthread_attr_setstackaddr()> and
I<pthread_attr_getstackaddr()> return a value of 0. Otherwise, an error
number is returned to indicate the error.

The I<pthread_attr_getstackaddr()> function stores the I<stackaddr>
attribute value in I<stackaddr> if successful.

=head1 ERRORS

No errors are defined.

These functions will not return an error code of [EINTR].

=head1 EXAMPLES

None.

=head1 APPLICATION USAGE

None.

=head1 FUTURE DIRECTIONS

None.

=head1 SEE ALSO

I<pthread_attr_init()>,
I<pthread_attr_setdetachstate()>,
I<pthread_attr_setstacksize()>,
I<pthread_create()>,
I<<limits.h>>,
I<<pthread.h>>.

=head1 ______________________________________________________________________

=head1 NAME

B<pthread_attr_setstacksize,> B<pthread_attr_getstacksize>
- set and get stacksize attribute

=head1 SYNOPSIS

#include <pthread.h>

int pthread_attr_setstacksize(pthread_attr_t *I<attr>, size_t I<stacksize>);
int pthread_attr_getstacksize(const pthread_attr_t *I<attr>,
size_t *I<stacksize>);

=head1 DESCRIPTION

The functions
I<pthread_attr_setstacksize()>
and
I<pthread_attr_getstacksize()>,
respectively, set and get the thread creation
I<stacksize>
attribute in the
I<attr>
object.

The
I<stacksize>
attribute defines the minimum stack size (in bytes) allocated for
the created threads stack.

=head1 RETURN VALUE

Upon successful completion,
I<pthread_attr_setstacksize()>
and
I<pthread_attr_getstacksize()>
return a value of 0.
Otherwise, an error number is returned to indicate the error.
The
I<pthread_attr_getstacksize()>
function stores the
I<stacksize>
attribute value in
I<stacksize>
if successful.

=head1 ERRORS

The
I<pthread_attr_setstacksize()>
function will fail if:

=over 4