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Multithreaded Programming Guide     Oracle Solaris 11.1 Information Library
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Document Information

Preface

1.  Covering Multithreading Basics

2.  Basic Threads Programming

3.  Thread Attributes

4.  Programming with Synchronization Objects

Mutual Exclusion Lock Attributes

Initializing a Mutex Attribute Object

pthread_mutexattr_init Syntax

pthread_mutexattr_init Return Values

Destroying a Mutex Attribute Object

pthread_mutexattr_destroy Syntax

pthread_mutexattr_destroy Return Values

Setting the Scope of a Mutex

pthread_mutexattr_setpshared Syntax

pthread_mutexattr_setpshared Return Values

Getting the Scope of a Mutex

pthread_mutexattr_getpshared Syntax

pthread_mutexattr_getpshared Return Values

Setting the Mutex Type Attribute

pthread_mutexattr_settype Syntax

pthread_mutexattr_settype Return Values

Getting the Mutex Type Attribute

pthread_mutexattr_gettype Syntax

pthread_mutexattr_gettype Return Values

Setting the Mutex Attribute's Protocol

pthread_mutexattr_setprotocol Syntax

pthread_mutexattr_setprotocol Return Values

Getting the Mutex Attribute's Protocol

pthread_mutexattr_getprotocol Syntax

pthread_mutexattr_getprotocol Return Values

Setting the Mutex Attribute's Priority Ceiling

pthread_mutexattr_setprioceiling Syntax

pthread_mutexattr_setprioceiling Return Values

Getting the Mutex Attribute's Priority Ceiling

pthread_mutexattr_getprioceiling Syntax

pthread_mutexattr_getprioceiling Return Values

Setting the Mutex's Priority Ceiling

pthread_mutex_setprioceiling Syntax

pthread_mutex_setprioceiling Return Values

Getting the Mutex's Priority Ceiling

pthread_mutex_getprioceiling Syntax

pthread_mutex_getprioceiling Return Values

Setting the Mutex's Robust Attribute

pthread_mutexattr_setrobust_np Syntax

pthread_mutexattr_setrobust_np Return Values

Getting the Mutex's Robust Attribute

pthread_mutexattr_getrobust_np Syntax

pthread_mutexattr_getrobust_np Return Values

Using Mutual Exclusion Locks

Initializing a Mutex

pthread_mutex_init Syntax

pthread_mutex_init Return Values

Making a Mutex Consistent

pthread_mutex_consistent_np Syntax

pthread_mutex_consistent_np Return Values

Locking a Mutex

pthread_mutex_lock Syntax

pthread_mutex_lock Return Values

Unlocking a Mutex

pthread_mutex_unlock Syntax

pthread_mutex_unlock Return Values

Locking a Mutex Without Blocking

pthread_mutex_trylock Syntax

pthread_mutex_trylock Return Values

Locking a Mutex Before a Specified Absolute Time

pthread_mutex_timedlock() Syntax

pthread_mutex_timedlock() Return Values

Locking a Mutex Within a Specified Time Interval

pthread_mutex_reltimedlock_np() Syntax

pthread_mutex_reltimedlock_np() Return Values

Destroying a Mutex

pthread_mutex_destroy Syntax

pthread_mutex_destroy Return Values

Code Examples of Mutex Locking

Examples of Using Lock Hierarchies

Examples of Using Nested Locking With a Singly-Linked List

Example of Nested Locking With a Circularly-Linked List

Using Spin Locks

Initializing a Spin Lock

pthread_spin_init() Syntax

pthread_spin_init() Return Values

Acquiring a Spin Lock

pthread_spin_lock() Syntax

pthread_spin_lock() Return Values

Acquiring a Non-Blocking Spin Lock

pthread_spin_trylock() Syntax

pthread_spin_trylock() Return Values

Unlocking a Spin Lock

pthread_spin_unlock() Syntax

pthread_spin_unlock() Return Values

Destroying a Spin Lock

pthread_spin_destroy() Syntax

pthread_spin_destroy() Return Values

Condition Variable Attributes

Initializing a Condition Variable Attribute

pthread_condattr_init Syntax

pthread_condattr_init Return Values

Removing a Condition Variable Attribute

pthread_condattr_destroy Syntax

pthread_condattr_destroy Return Values

Setting the Scope of a Condition Variable

pthread_condattr_setpshared Syntax

pthread_condattr_setpshared Return Values

Getting the Scope of a Condition Variable

pthread_condattr_getpshared Syntax

pthread_condattr_getpshared Return Values

Setting the Clock Selection Condition Variable

pthread_condattr_setclock Syntax

pthread_condattr_setclock Returns

Getting the Clock Selection Condition Variable

pthread_condattr_getclock Syntax

pthread_condattr_getclock Returns

Using Condition Variables

Initializing a Condition Variable

pthread_cond_init Syntax

pthread_cond_init Return Values

Blocking on a Condition Variable

pthread_cond_wait Syntax

pthread_cond_wait Return Values

Unblocking One Thread

pthread_cond_signal Syntax

pthread_cond_signal Return Values

Blocking Until a Specified Time

pthread_cond_timedwait Syntax

pthread_cond_timedwait Return Values

Blocking For a Specified Interval

pthread_cond_reltimedwait_np Syntax

pthread_cond_reltimedwait_np Return Values

Unblocking All Threads

pthread_cond_broadcast Syntax

pthread_cond_broadcast Return Values

Destroying the Condition Variable State

pthread_cond_destroy Syntax

pthread_cond_destroy Return Values

Lost Wake-Up Problem

Producer and Consumer Problem

Synchronization With Semaphores

Named and Unnamed Semaphores

Counting Semaphores Overview

Initializing a Semaphore

sem_init Syntax

Initializing Semaphores With Intraprocess Scope

Initializing Semaphores With Interprocess Scope

sem_init Return Values

Incrementing a Semaphore

sem_post Syntax

sem_post Return Values

Blocking on a Semaphore Count

sem_wait Syntax

sem_wait Return Values

Decrementing a Semaphore Count

sem_trywait Syntax

sem_trywait Return Values

Destroying the Semaphore State

sem_destroy Syntax

sem_destroy Return Values

Producer and Consumer Problem Using Semaphores

Read-Write Lock Attributes

Initializing a Read-Write Lock Attribute

pthread_rwlockattr_init Syntax

pthread_rwlockattr_init Return Values

Destroying a Read-Write Lock Attribute

pthread_rwlockattr_destroy Syntax

pthread_rwlockattr_destroy Return Values

Setting a Read-Write Lock Attribute

pthread_rwlockattr_setpshared Syntax

pthread_rwlockattr_setpshared Return Values

Getting a Read-Write Lock Attribute

pthread_rwlockattr_getpshared Syntax

pthread_rwlockattr_getpshared Return Values

Using Read-Write Locks

Initializing a Read-Write Lock

pthread_rwlock_init Syntax

pthread_rwlock_init Return Values

Acquiring the Read Lock on Read-Write Lock

pthread_rwlock_rdlock Syntax

pthread_rwlock_rdlock Return Values

Acquiring a Read Lock on a Read-Write Lock Before a Specified Absolute Time

pthread_rwlock_timedrdlock Syntax

pthread_rwlock_timedrdlock Return Values

Acquiring a Non-Blocking Read Lock on a Read-Write Lock

pthread_rwlock_tryrdlock Syntax

pthread_rwlock_tryrdlock Return Values

Acquiring the Write Lock on a Read-Write Lock

pthread_rwlock_wrlock Syntax

pthread_rwlock_wrlock Return Values

Acquiring a Non-blocking Write Lock on a Read-Write Lock

pthread_rwlock_trywrlock Syntax

pthread_rwlock_trywrlock Return Values

Acquiring a Write Lock on a Read-Write Lock Before a Specified Absolute Time

pthread_rwlock_timedwrlock Syntax

pthread_rwlock_timedwrlock Returns

Unlocking a Read-Write Lock

pthread_rwlock_unlock Syntax

pthread_rwlock_unlock Return Values

Destroying a Read-Write Lock

pthread_rwlock_destroy Syntax

pthread_rwlock_destroy Return Values

Using Barrier Synchronization

Initializing a Synchronization Barrier

pthread_barrier_init() Syntax

pthread_barrier_init() Return Values

Waiting for Threads to Synchronize at a Barrier

pthread_barrier_wait() Syntax

pthread_barrier_wait() Return Values

Destroying a Synchronization Barrier

pthread_barrier_destroy Syntax

pthread_barrier_destroy Return Values

Initializing a Barrier Attributes Object

pthread_barrierattr_init() Syntax

pthread_barrierattr_init() Return Values

Setting a Barrier Process-Shared Attribute

pthread_barrierattr_setpshared() Syntax

pthread_barrierattr_setpshared() Return Values

Getting a Barrier Process-Shared Attribute

pthread_barrierattr_getpshared() Syntax

pthread_barrierattr_getpshared() Return Values

Destroying a Barrier Attributes Object

pthread_barrierattr_destroy() Syntax

pthread_barrierattr_destroy() Return Values

Synchronization Across Process Boundaries

Producer and Consumer Problem Example

Comparing Primitives

5.  Programming With the Oracle Solaris Software

6.  Programming With Oracle Solaris Threads

7.  Safe and Unsafe Interfaces

8.  Compiling and Debugging

9.  Programming Guidelines

A.  Extended Example: A Thread Pool Implementation

Index

Mutual Exclusion Lock Attributes

Use mutual exclusion locks (mutexes) to serialize thread execution. Mutual exclusion locks synchronize threads, usually by ensuring that only one thread at a time executes a critical section of code. Mutex locks can also preserve single-threaded code.

To change the default mutex attributes, you can declare and initialize an attribute object. Often, the mutex attributes are set in one place at the beginning of the application so the attributes can be located quickly and modified easily. Table 4-1 lists the functions that manipulate mutex attributes.

Table 4-1 Mutex Attributes Routines

Operation
Related Function Description
Initialize a mutex attribute object
Destroy a mutex attribute object
Set the scope of a mutex
Get the scope of a mutex
Set the mutex type attribute
Get the mutex type attribute
Set mutex attribute's protocol
Get mutex attribute's protocol
Set mutex attribute's priority ceiling
Get mutex attribute's priority ceiling
Set mutex's priority ceiling
Get mutex's priority ceiling
Set mutex's robust attribute
Get mutex's robust attribute

Initializing a Mutex Attribute Object

Use pthread_mutexattr_init(3C) to initialize attributes that are associated with the mutex object to their default values. Storage for each attribute object is allocated by the threads system during execution.

pthread_mutexattr_init Syntax

int pthread_mutexattr_init(pthread_mutexattr_t *mattr);
#include <pthread.h>

pthread_mutexattr_t mattr;
int ret;

/* initialize an attribute to default value */
ret = pthread_mutexattr_init(&mattr); 

mattr is an opaque type that contains a system-allocated attribute object. See Table 4-2 for information about the attributes in the mattr object.

Before a mutex attribute object can be reinitialized, the object must first be destroyed by a call to pthread_mutexattr_destroy(3C). The pthread_mutexattr_init() call results in the allocation of an opaque object. If the object is not destroyed, a memory leak results.

Table 4-2 Default Attribute Values for mattr

Attribute
Value
Result
pshared
PTHREAD_PROCESS_PRIVATE
The initialized mutex can be used within a process. Only those threads created by the same process can operate on the mutex.
type
PTHREAD_MUTEX_DEFAULT
The Oracle Solaris Pthreads implementation maps PTHREAD_MUTEX_DEFAULT to PTHREAD_MUTEX_NORMAL, which does not detect deadlock.
protocol
PTHREAD_PRIO_NONE
Thread priority and scheduling are not affected by the priority of the mutex owned by the thread.
prioceiling
The prioceiling value is drawn from the existing priority range for the SCHED_FIFO policy, as returned by the sched_get_priority_min() and sched_get_priority_max() functions. This priority range is determined by the Oracle Solaris version on which the mutex is created.
robustness
PTHREAD_MUTEX_STALLED_NP
When the owner of a mutex dies, all future calls to pthread_mutex_lock() for this mutex will be blocked from progress.

pthread_mutexattr_init Return Values

pthread_mutexattr_init() returns zero after completing successfully. Any other return value indicates that an error occurred. If either of the following conditions occurs, the function fails and returns the corresponding value.

ENOMEM

Description: Insufficient memory exists to initialize the mutex attribute object.

Destroying a Mutex Attribute Object

pthread_mutexattr_destroy(3C) deallocates the storage space used to maintain the attribute object created by pthread_mutexattr_init().

pthread_mutexattr_destroy Syntax

int pthread_mutexattr_destroy(pthread_mutexattr_t *mattr)
#include <pthread.h> 
pthread_mutexattr_t mattr; 
int ret; 
/* destroy an attribute */ 
ret = pthread_mutexattr_destroy(&mattr); 

pthread_mutexattr_destroy Return Values

pthread_mutexattr_destroy() returns zero after completing successfully. Any other return value indicates that an error occurred. If the following condition occurs, the function fails and returns the corresponding value.

EINVAL

Description: The value specified by mattr is invalid.

Setting the Scope of a Mutex

pthread_mutexattr_setpshared(3C) sets the scope of the mutex variable.

pthread_mutexattr_setpshared Syntax

int pthread_mutexattr_setpshared(pthread_mutexattr_t *restrict mattr,
         int *restrict pshared);
#include <pthread.h> 
pthread_mutexattr_t mattr; 
int ret; 
ret = pthread_mutexattr_init(&mattr); 
/* * resetting to its default value: private */ 
ret = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_PRIVATE);

The scope of a mutex variable can be either process private (intraprocess) or system wide (interprocess). To share the mutex among threads from more than one process, create the mutex in shared memory with the pshared attribute set to PTHREAD_PROCESS_SHARED .

If the mutex pshared attribute is set to PTHREAD_PROCESS_PRIVATE , only those threads created by the same process can operate on the mutex.

pthread_mutexattr_setpshared Return Values

pthread_mutexattr_setpshared() returns zero after completing successfully. Any other return value indicates that an error occurred. If the following condition occurs, the function fails and returns the corresponding value.

EINVAL

Description: The value specified by mattr is invalid.

Getting the Scope of a Mutex

pthread_mutexattr_getpshared(3C) returns the scope of the mutex variable defined by pthread_mutexattr_setpshared().

pthread_mutexattr_getpshared Syntax

int pthread_mutexattr_getpshared(pthread_mutexattr_t *restrict mattr, 
          int *restrict pshared);
#include <pthread.h> 
pthread_mutexattr_t mattr; 
int pshared, ret; 
/* get pshared of mutex */ 
ret = pthread_mutexattr_getpshared(&mattr, &pshared); 

Get the current value of pshared for the attribute object mattr. The value is either PTHREAD_PROCESS_SHARED or PTHREAD_PROCESS_PRIVATE.

pthread_mutexattr_getpshared Return Values

pthread_mutexattr_getpshared() returns zero after completing successfully. Any other return value indicates that an error occurred. If the following condition occurs, the function fails and returns the corresponding value.

EINVAL

Description: The value specified by mattr is invalid.

Setting the Mutex Type Attribute

pthread_mutexattr_settype(3C) sets the mutex type attribute.

pthread_mutexattr_settype Syntax

#include <pthread.h>

int pthread_mutexattr_settype(pthread_mutexattr_t  *attr , int type);

The default value of the type attribute is PTHREAD_MUTEX_DEFAULT.

The type argument specifies the type of mutex. The following list describes the valid mutex types:

PTHREAD_MUTEX_NORMAL

Description: This type of mutex does not detect deadlock. A thread attempting to relock this mutex without first unlocking the mutex deadlocks. Attempting to unlock a mutex locked by a different thread results in undefined behavior. Attempting to unlock an unlocked mutex results in undefined behavior.

PTHREAD_MUTEX_ERRORCHECK

Description: This type of mutex provides error checking. A thread attempting to relock this mutex without first unlocking the mutex returns an error. A thread attempting to unlock a mutex that another thread has locked returns an error. A thread attempting to unlock an unlocked mutex returns an error.

PTHREAD_MUTEX_RECURSIVE

Description: A thread attempting to relock this mutex without first unlocking the mutex succeeds in locking the mutex. The relocking deadlock that can occur with mutexes of type PTHREAD_MUTEX_NORMAL cannot occur with this type of mutex. Multiple locks of this mutex require the same number of unlocks to release the mutex before another thread can acquire the mutex. A thread attempting to unlock a mutex that another thread has locked returns an error. A thread attempting to unlock an unlocked mutex returns an error.

PTHREAD_MUTEX_DEFAULT

Description: An implementation is allowed to map this attribute to one of the other mutex types. The Oracle Solaris implementation maps this attribute to PTHREAD_PROCESS_NORMAL.

pthread_mutexattr_settype Return Values

If successful, the pthread_mutexattr_settype function returns zero. Otherwise, an error number is returned to indicate the error.

EINVAL

Description: The value type or attr is invalid.

Getting the Mutex Type Attribute

pthread_mutexattr_gettype(3C) gets the mutex type attribute set by pthread_mutexattr_settype().

pthread_mutexattr_gettype Syntax

#include <pthread.h>

int pthread_mutexattr_gettype(pthread_mutexattr_t  *restrict attr , 
int  *restrict type);

The default value of the type attribute is PTHREAD_MUTEX_DEFAULT.

The type argument specifies the type of mutex. Valid mutex types include

For a description of each type, see pthread_mutexattr_settype Syntax.

pthread_mutexattr_gettype Return Values

On successful completion, pthread_mutexattr_gettype() returns 0. Any other return value indicates that an error occurred.

EINVAL

Description: The value specified by type is invalid.

Setting the Mutex Attribute's Protocol

pthread_mutexattr_setprotocol(3C) sets the protocol attribute of a mutex attribute object.

pthread_mutexattr_setprotocol Syntax

#include <pthread.h> 
int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr, 
          int protocol);

attr points to a mutex attribute object created by an earlier call to pthread_mutexattr_init().

protocol defines the protocol that is applied to the mutex attribute object.

The value of protocol that is defined in pthread.h can be one of the following values: PTHREAD_PRIO_NONE , PTHREAD_PRIO_INHERIT, or PTHREAD_PRIO_PROTECT .

The PTHREAD_PRIO_INHERIT and PTHREAD_PRIO_PROTECT mutex attributes are usable only by privileged processes running in the realtime (RT) scheduling class SCHED_FIFO or SCHED_RR.

A thread can simultaneously own several mutexes initialized with a mix of PTHREAD_PRIO_INHERIT and PTHREAD_PRIO_PROTECT. In this case, the thread executes at the highest priority obtained by either of these protocols.

pthread_mutexattr_setprotocol Return Values

On successful completion, pthread_mutexattr_setprotocol() returns 0. Any other return value indicates that an error occurred.

If either of the following conditions occurs, pthread_mutexattr_setprotocol() might fail and return the corresponding value.

EINVAL

Description: The value specified by attr or protocol is not valid.

EPERM

Description: The caller does not have the privilege to perform the operation.

Getting the Mutex Attribute's Protocol

pthread_mutexattr_getprotocol(3C) gets the protocol attribute of a mutex attribute object.

pthread_mutexattr_getprotocol Syntax

#include <pthread.h> 
int pthread_mutexattr_getprotocol(const pthread_mutexattr_t *restrict attr, 
int *restrict protocol);

attr points to a mutex attribute object created by an earlier call to pthread_mutexattr_init().

protocol contains one of the following protocol attributes: PTHREAD_PRIO_NONE, PTHREAD_PRIO_INHERIT, or PTHREAD_PRIO_PROTECT which are defined by the header <pthread.h>.

pthread_mutexattr_getprotocol Return Values

On successful completion, pthread_mutexattr_getprotocol() returns 0. Any other return value indicates that an error occurred.

If either of the following conditions occurs, pthread_mutexattr_getprotocol() might fail and return the corresponding value.

EINVAL

Description: The value specified by attr is NULL, or the value specified by attr or protocol is invalid.

EPERM

Description: The caller does not have the privilege to perform the operation.

Setting the Mutex Attribute's Priority Ceiling

pthread_mutexattr_setprioceiling(3C) sets the priority ceiling attribute of a mutex attribute object.

pthread_mutexattr_setprioceiling Syntax

#include <pthread.h> 
int pthread_mutexattr_setprioceiling(pthread_mutexatt_t *attr, int prioceiling);

attr points to a mutex attribute object created by an earlier call to pthread_mutexattr_init().

prioceiling specifies the priority ceiling of initialized mutexes. The ceiling defines the minimum priority level at which the critical section guarded by the mutex is executed. prioceiling falls within the maximum range of priorities defined by SCHED_FIFO. To avoid priority inversion, set prioceiling to a priority higher than or equal to the highest priority of all threads that might lock the particular mutex.

pthread_mutexattr_setprioceiling Return Values

On successful completion, pthread_mutexattr_setprioceiling() returns 0. Any other return value indicates that an error occurred.

If either of the following conditions occurs, pthread_mutexattr_setprioceiling() might fail and return the corresponding value.

EINVAL

Description: The value specified by attr is NULL or invalid or prioceiling is invalid.

EPERM

Description: The caller does not have the privilege to perform the operation.

Getting the Mutex Attribute's Priority Ceiling

pthread_mutexattr_getprioceiling(3C) gets the priority ceiling attribute of a mutex attribute object.

pthread_mutexattr_getprioceiling Syntax

#include <pthread.h> 
int pthread_mutexattr_getprioceiling(const pthread_mutexatt_t *restrict attr, 
           int *restrict prioceiling);

attr designates the attribute object created by an earlier call to pthread_mutexattr_init().

pthread_mutexattr_getprioceiling() returns the priority ceiling of initialized mutexes in prioceiling. The ceiling defines the minimum priority level at which the critical section guarded by the mutex is executed. prioceiling falls within the maximum range of priorities defined by SCHED_FIFO. To avoid priority inversion, set prioceiling to a priority higher than or equal to the highest priority of all threads that might lock the particular mutex.

pthread_mutexattr_getprioceiling Return Values

On successful completion, pthread_mutexattr_getprioceiling() returns 0. Any other return value indicates that an error occurred.

If either of the following conditions occurs, pthread_mutexattr_getprioceiling() might fail and return the corresponding value.

EINVAL

Description: The value specified by attr is NULL.

EPERM

Description: The caller does not have the privilege to perform the operation.

Setting the Mutex's Priority Ceiling

pthread_mutexattr_setprioceiling(3C) sets the priority ceiling of a mutex.

pthread_mutex_setprioceiling Syntax

#include <pthread.h> 
int pthread_mutex_setprioceiling(pthread_mutex_t *restrict mutex, 
          int prioceiling, int *restrict old_ceiling);

pthread_mutex_setprioceiling() changes the priority ceiling, prioceiling, of a mutex, mutex. pthread_mutex_setprioceiling() locks a mutex if unlocked, or blocks until pthread_mutex_setprioceiling() successfully locks the mutex, changes the priority ceiling of the mutex and releases the mutex. The process of locking the mutex need not adhere to the priority protect protocol.

If pthread_mutex_setprioceiling() succeeds, the previous value of the priority ceiling is returned in old_ceiling. If pthread_mutex_setprioceiling() fails, the mutex priority ceiling remains unchanged.

pthread_mutex_setprioceiling Return Values

On successful completion, pthread_mutex_setprioceiling() returns 0. Any other return value indicates that an error occurred.

If any of the following conditions occurs, pthread_mutex_setprioceiling() might fail and return the corresponding value.

EINVAL

Description: The priority requested by prioceiling is out of range.

EINVAL

Description: The mutex was not initialized with its protocol attribute having the value of THREAD_PRIO_PROTECT.

EPERM

Description: The caller does not have the privilege to perform the operation.

Getting the Mutex's Priority Ceiling

pthread_mutexattr_getprioceiling(3C) gets the priority ceiling of a mutex.

pthread_mutex_getprioceiling Syntax

#include <pthread.h> 
int pthread_mutex_getprioceiling(const pthread_mutex_t *restrict mutex, 
          int *restrict prioceiling);

pthread_mutex_getprioceiling() returns the priority ceiling, prioceiling of a mutex.

pthread_mutex_getprioceiling Return Values

On successful completion, pthread_mutex_getprioceiling() returns 0. Any other return value indicates that an error occurred.

If any of the following conditions occurs, pthread_mutexatt_getprioceiling() fails and returns the corresponding value.

If any of the following conditions occurs, pthread_mutex_getprioceiling() might fail and return the corresponding value.

EINVAL

Description: The value specified by mutex does not refer to a currently existing mutex.

EPERM

Description: The caller does not have the privilege to perform the operation.

Setting the Mutex's Robust Attribute

pthread_mutexattr_setrobust_np sets the robust attribute of a mutex attribute object.

pthread_mutexattr_setrobust_np Syntax

#include <pthread.h> 
int pthread_mutexattr_setrobust_np(pthread_mutexattr_t *attr, int *robustness);

Note - pthread_mutexattr_setrobust_np() applies only if the symbol _POSIX_THREAD_PRIO_INHERIT is defined.

In the Oracle Solaris 10 and prior releases, the PTHREAD_MUTEX_ROBUST_NP attribute can only be applied to mutexes that are also marked with the PTHREAD_PRIO_INHERIT protocol attribute. This restriction is lifted in subsequent Oracle Solaris releases.


attr points to the mutex attribute object previously created by a call to pthread_mutexattr_init().

robustness defines the behavior when the owner of the mutex terminates without unlocking the mutex, usually because its process terminated abnormally. The value of robustness that is defined in pthread.h is PTHREAD_MUTEX_ROBUST_NP or PTHREAD_MUTEX_STALLED_NP. The default value is PTHREAD_MUTEX_STALLED_NP .

pthread_mutexattr_setrobust_np Return Values

On successful completion, pthread_mutexattr_setrobust_np() returns 0. Any other return value indicates that an error occurred.

pthread_mutexattr_setrobust_np() might fail if the following condition occurs:

EINVAL

Description: The value specified by attr or robustness is invalid.

Getting the Mutex's Robust Attribute

pthread_mutexattr_getrobust_np gets the robust attribute of a mutex attribute object.

pthread_mutexattr_getrobust_np Syntax

#include <pthread.h> 
int pthread_mutexattr_getrobust_np(const pthread_mutexattr_t *attr, int *robustness);

attr points to the mutex attribute object previously created by a call to pthread_mutexattr_init().

robustness is the value of the robust attribute of a mutex attribute object.

pthread_mutexattr_getrobust_np Return Values

On successful completion, pthread_mutexattr_getrobust_np() returns 0. Any other return value indicates that an error occurred.

pthread_mutexattr_getrobust_np() might fail if the following condition occurs:

EINVAL

Description: The value specified by attr or robustness is invalid.