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Multithreaded Programming Guide Oracle Solaris 11.1 Information Library |
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Multithreaded Programming Guide Oracle Solaris 11.1 Information Library |
1. Covering Multithreading Basics
4. Programming with Synchronization Objects
Mutual Exclusion Lock Attributes
Initializing a Mutex Attribute Object
pthread_mutexattr_init Return Values
Destroying a Mutex Attribute Object
pthread_mutexattr_destroy Syntax
pthread_mutexattr_destroy Return Values
pthread_mutexattr_setpshared Syntax
pthread_mutexattr_setpshared Return Values
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
pthread_mutex_init Return Values
pthread_mutex_consistent_np Syntax
pthread_mutex_consistent_np Return Values
pthread_mutex_lock Return Values
pthread_mutex_unlock Return Values
Locking a Mutex Without Blocking
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
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
pthread_spin_init() Return Values
pthread_spin_lock() Return Values
Acquiring a Non-Blocking Spin Lock
pthread_spin_trylock() Return Values
pthread_spin_unlock() Return Values
pthread_spin_destroy() Return Values
Initializing a Condition Variable Attribute
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
Initializing a Condition Variable
pthread_cond_init Return Values
Blocking on a Condition Variable
pthread_cond_wait Return Values
pthread_cond_signal Return Values
Blocking Until a Specified Time
pthread_cond_timedwait Return Values
Blocking For a Specified Interval
pthread_cond_reltimedwait_np Syntax
pthread_cond_reltimedwait_np Return Values
pthread_cond_broadcast Return Values
Destroying the Condition Variable State
pthread_cond_destroy Return Values
Synchronization With Semaphores
Initializing Semaphores With Intraprocess Scope
Initializing Semaphores With Interprocess Scope
Decrementing a Semaphore Count
Destroying the Semaphore State
Producer and Consumer Problem Using Semaphores
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
Initializing a Read-Write Lock
pthread_rwlock_init Return Values
Acquiring the Read Lock on Read-Write Lock
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 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
pthread_rwlock_unlock Return Values
pthread_rwlock_destroy Return Values
Initializing a Synchronization Barrier
pthread_barrier_init() Return Values
Waiting for Threads to Synchronize at a Barrier
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
5. Programming With the Oracle Solaris Software
6. Programming With Oracle Solaris Threads
Use condition variables to atomically block threads until a particular condition is true. Always use condition variables together with a mutex lock.
With a condition variable, a thread can atomically block until a condition is satisfied. The condition is tested under the protection of a mutual exclusion lock (mutex).
When the condition is false, a thread usually blocks on a condition variable and atomically releases the mutex waiting for the condition to change. When another thread changes the condition, that thread can signal the associated condition variable to cause one or more waiting threads to perform the following actions:
Wake up
Acquire the mutex again
Re-evaluate the condition
Condition variables can be used to synchronize threads among processes in the following situations:
The threads are allocated in memory that can be written to
The memory is shared by the cooperating processes
The scheduling policy determines how blocking threads are awakened. The default scheduling policy, SCHED_OTHER, does not specify the order in which threads are awakened. Under the SCHED_FIFO and SCHED_RR real-time scheduling policies, threads are awakened in priority order.
The attributes for condition variables must be set and initialized before the condition variables can be used. The functions that manipulate condition variable attributes are listed in Table 4-4.
Table 4-4 Condition Variable Attributes
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Use pthread_condattr_init(3C) to initialize attributes that are associated with this object to their default values. Storage for each attribute object is allocated by the threads system during execution.
int pthread_condattr_init(pthread_condattr_t *cattr);
#include <pthread.h> pthread_condattr_t cattr; int ret; /* initialize an attribute to default value */ ret = pthread_condattr_init(&cattr);
The default value of the pshared attribute when this function is called is PTHREAD_PROCESS_PRIVATE. This value of pshared means that the initialized condition variable can be used within a process.
cattr is an opaque data type that contains a system-allocated attribute object. The possible values of cattr's scope are PTHREAD_PROCESS_PRIVATE and PTHREAD_PROCESS_SHARED . PTHREAD_PROCESS_PRIVATE is the default value.
Before a condition variable attribute can be reused, the attribute must first be reinitialized by pthread_condattr_destroy(3C). The pthread_condattr_init() call returns a pointer to an opaque object. If the object is not destroyed, a memory leak results.
pthread_condattr_init() returns zero after completing successfully. Any other return value indicates that an error occurred. When either of the following conditions occurs, the function fails and returns the corresponding value.
ENOMEM
Description: Insufficient memory allocated to initialize the thread attributes object.
EINVAL
Description: The value specified by cattr is invalid.
Use pthread_condattr_destroy(3C) to remove storage and render the attribute object invalid.
int pthread_condattr_destroy(pthread_condattr_t *cattr);
#include <pthread.h> pthread_condattr_t cattr; int ret; /* destroy an attribute */ ret = pthread_condattr_destroy(&cattr);
pthread_condattr_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 cattr is invalid.
pthread_condattr_setpshared(3C) sets the scope of a condition variable to either process private (intraprocess) or system wide (interprocess).
int pthread_condattr_setpshared(pthread_condattr_t *cattr, int pshared);
#include <pthread.h> pthread_condattr_t cattr; int ret; /* all processes */ ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED); /* within a process */ ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_PRIVATE);
A condition variable created with the pshared attribute set in shared memory to PTHREAD_PROCESS_SHARED, can be shared among threads from more than one process.
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_PROCESS_PRIVATE is the default value. PTHREAD_PROCESS_PRIVATE behaves like a local condition variable. The behavior of PTHREAD_PROCESS_SHARED is equivalent to a global condition variable.
pthread_condattr_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 of cattr is invalid, or the pshared value is invalid.
pthread_condattr_getpshared(3C) gets the current value of pshared for the attribute object cattr.
int pthread_condattr_getpshared(const pthread_condattr_t *restrict cattr,
int *restrict pshared);#include <pthread.h> pthread_condattr_t cattr; int pshared; int ret; /* get pshared value of condition variable */ ret = pthread_condattr_getpshared(&cattr, &pshared);
The value of the attribute object is either PTHREAD_PROCESS_SHARED or PTHREAD_PROCESS_PRIVATE.
pthread_condattr_getpshared() returns zero after completing successfully. Any other return value indicates that an error occurred. When the following condition occurs, the function fails and returns the corresponding value.
EINVAL
Description: The value of cattr is invalid.
Use the pthread_condattr_setclock(3C) function to set the clock attribute in an initialized attributes object referenced by attr. If pthread_condattr_setclock() is called with a clock_id argument that refers to a CPU-time clock, the call fails. The clock attribute is the clock ID of the clock that is used to measure the timeout service of pthread_cond_timedwait(). The default value of the clock attribute refers to the system clock, CLOCK_REALTIME. At this time, the only other possible value for the clock attribute is CLOCK_MONOTONIC.
int pthread_condattr_setclock(pthread_condattr_t attr,
clockid_t clock_id);#include <pthread.h> pthread_condattr_t attr clockid_t clock_id int ret ret = pthread_condattr_setclock(&attr &clock_id
pthread_condattr_setclock() returns zero after completing successfully. Any other return value indicates that an error occurred. When the following condition occurs, the function fails and returns the corresponding value.
EINVAL
Description: The value specified by clock_id does not refer to a known clock, or is a CPU-time clock.
Use the pthread_condattr_getclock(3C) function to obtain the value of the clock attribute from the attributes object referenced by attr. The clock attribute is the clock ID of the clock that is used to measure the timeout service of pthread_cond_timedwait().
int pthread_condattr_getclock(const pthread_condattr_t *restrict attr,
clockid_t *restrict clock_id);#include <pthread.h> pthread_condattr_t attr clockid_t clock_id int ret ret = pthread_condattr_getclock(&attr &clock_id
pthread_condattr_getclock() returns zero after completing successfully and stores the value of the clock attribute of attr into the object referenced by the clock_id argument. Any other return value indicates that an error occurred. When the following condition occurs, the function fails and returns the corresponding value.
EINVAL
Description: The value of attr is invalid.
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