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Condition Variables(3) globus common Condition Variables(3)

NAME

Condition Variables -

Data Structures


union globus_cond_t
 
Condition variable. union globus_condattr_t
 
Condition variable attribute.

Functions


int globus_cond_init (globus_cond_t *cond, globus_condattr_t *attr)
 
int globus_cond_destroy (globus_cond_t *cond)
 
int globus_cond_wait (globus_cond_t *cond, globus_mutex_t *mutex)
 
int globus_cond_timedwait (globus_cond_t *cond, globus_mutex_t *mutex, globus_abstime_t *abstime)
 
int globus_cond_signal (globus_cond_t *cond)
 
int globus_cond_broadcast (globus_cond_t *cond)
 
int globus_condattr_init (globus_condattr_t *cond_attr)
 
int globus_condattr_destroy (globus_condattr_t *cond_attr)
 
int globus_condattr_setspace (globus_condattr_t *cond_attr, int space)
 
int globus_condattr_getspace (globus_condattr_t *cond_attr, int *space)
 

Detailed Description

The globus_cond_t provides condition variables for signalling events between threads interested in particular state. One or many threads may wait on a condition variable until it is signalled, at which point they can attempt to lock a mutex related to that condition's state and process the event.
In a non-threaded model, the condition variable wait operations are used to poll the event driver to handle any operations that have been scheduled for execution by the globus_callback system or I/O system. In this way, applications written to use those systems to handle nonblocking operations will work with either a threaded or nonthreaded runtime choice.

Function Documentation

int globus_cond_init (globus_cond_t *cond, globus_condattr_t *attr)

Initialize a condition variable
The globus_cond_init() function creates a condition variable that can be used for event signalling between threads. Parameters:
cond Pointer to the condition variable to initialize.
 
attr Condition variable attributes.
Returns:
On success, globus_cond_init() initializes the condition variable and returns GLOBUS_SUCCESS. Otherwise, a non-0 value is returned.
 

int globus_cond_destroy (globus_cond_t *cond)

Destroy a condition variable. .PP 
The globus_cond_destroy() function destroys the condition variable
pointed to by its @a cond parameter. After a condition variable is
destroyed it may no longer be used
unless it is again initialized by globus_cond_init().
Parameters:
cond The condition variable to destroy.
Returns:
On success, globus_cond_destroy() returns GLOBUS_SUCCESS. Otherwise, a non-zero implementation-specific error value is returned.
 

int globus_cond_wait (globus_cond_t *cond, globus_mutex_t *mutex)

Wait for a condition to be signalled. .PP 
The globus_cond_wait() function atomically unlocks the mutex pointed to
by the @a mutex parameter and blocks the current thread until the
condition variable pointed to by @a cond is signalled by either
globus_cond_signal() or globus_cond_broadcast(). Behavior is undefined
if globus_cond_wait() is called with the mutex pointed to by the @a
mutex variable unlocked.
Parameters:
cond The condition variable to wait for.
 
mutex The mutex associated with the condition state.
Returns:
On success, globus_cond_wait() unlocks the mutex and blocks the current thread until it has been signalled, returning GLOBUS_SUCCES. Otherwise, globus_cond_wait() returns an implementation-specific non-zero error value.
 

int globus_cond_timedwait (globus_cond_t *cond, globus_mutex_t *mutex, globus_abstime_t *abstime)

Wait for a condition to be signalled. .PP 
The globus_cond_timedwait() function atomically unlocks the mutex
pointed to by the @a mutex parameter and blocks the current thread until
either the condition variable pointed to by @a cond is signalled by
another thread or the current time exceeds the value pointed to by the
@a abstime parameter. If the timeout occurs before the condition is
signalled, globus_cond_timedwait() returns ETIMEDOUT. Behavior is
undefined if globus_cond_timedwait() is called with the mutex pointed to
by the @a mutex variable unlocked.
Parameters:
cond The condition variable to wait for.
 
mutex The mutex associated with the condition state.
 
abstime The absolute time to wait until.
Returns:
On success, globus_cond_timedwait() unlocks the mutex and blocks the current thread until it has been signalled, returning GLOBUS_SUCCES. If a timeout occurs before signal, globus_cond_timedwait() unlocks the mutex and returns ETIMEDOUT. Otherwise, globus_cond_timedwait() returns an implementation-specific non-zero error value.
 

int globus_cond_signal (globus_cond_t *cond)

Signal a condition to a thread. .PP 
The globus_cond_signal() function signals a condition as occurring.
This will unblock at least one thread waiting for that condition.
Parameters:
cond A pointer to the condition variable to signal.
Returns:
Upon success, globus_cond_signal() returns GLOBUS_SUCCESS. If an error occurs, globus_cond_signal() returns an implementation-specific non-zero error code.
 

int globus_cond_broadcast (globus_cond_t *cond)

Signal a condition to multiple threads. .PP 
The globus_cond_signal() function signals a condition as occurring.
This will unblock all threads waiting for that condition.
Parameters:
cond A pointer to the condition variable to signal.
Returns:
Upon success, globus_cond_broadcast() returns GLOBUS_SUCCESS. If an error occurs, globus_cond_broadcast() returns an implementation-specific non-zero error code.
 

int globus_condattr_init (globus_condattr_t *cond_attr)

Initialize a condition variable attribute. .PP 
The globus_condattr_init() function initializes the condition variable
attribute structure pointed to by its @a cond_attr parameter to the
system default values.
Parameters:
cond_attr Attribute structure to initialize.
Returns:
Upon success, globus_condattr_init() returns GLOBUS_SUCCESS and modifies the attribute pointed to by cond_attr. If an error occurs, globus_condattr_init() returns an implementation-specific non-zero error code.
 

int globus_condattr_destroy (globus_condattr_t *cond_attr)

Destroy a condition attribute. .PP 
The globus_condattr_destroy() function destroys the condition variable
attribute structure pointed to by its @a cond_attr parameter.
Parameters:
cond_attr Attribute structure to destroy.
Returns:
Upon success, globus_condattr_destroy() returns GLOBUS_SUCCESS and modifies the attribute pointed to by cond_attr. If an error occurs, globus_condattr_destroy() returns an implementation-specific non-zero error code.
 

int globus_condattr_setspace (globus_condattr_t *cond_attr, intspace)

Set callback space associated with a condition variable attribute
The globus_condattr_setspace() function sets the callback space to use with condition variables created with this attribute. Callback spaces are used to control how callbacks are issued to different threads. See Callback Spaces for more information on callback spaces.
Parameters:
cond_attr Condition variable attribute to modify.
 
space Callback space to associate with the attribute.
Returns:
On success, globus_condattr_setspace() returns GLOBUS_SUCCESS and adds a reference to the callback space to the condition variable attribute. If an error occurs, globus_condattr_setspace() returns an implementation-specific non-zero error code.
 

int globus_condattr_getspace (globus_condattr_t *cond_attr, int *space)

Get callback space associated with a condition variable attribute
The globus_condattr_getspace() function copies the value of the callback space associated with a condition variable attribute to the integer pointed to by the space parameter. Parameters:
cond_attr Condition variable attribute to modify.
 
space Pointer to an integer to be set to point to the callback space associated with cond_attr.
Returns:
On success, globus_condattr_getspace() returns GLOBUS_SUCCESS and modifies the value pointed to by space to refer to the callback space associated with cond_attr. If an error occurs, globus_condattr_getspace() returns an implementation-specific non-zero error code.
 

Author

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Tue Nov 27 2012 Version 14.7