Condition Variables.
More...
Condition Variables.
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.
Signal a condition to multiple threads.
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.
Destroy a condition variable.
The globus_cond_destroy() function destroys the condition variable pointed to by its 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.
Initialize a condition variableThe 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.
Signal a condition to a thread.
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.
Wait for a condition to be signalled.
The globus_cond_timedwait() function atomically unlocks the mutex pointed to by the mutex parameter and blocks the current thread until either the condition variable pointed to by cond is signalled by another thread or the current time exceeds the value pointed to by the 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 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.
Wait for a condition to be signalled.
The globus_cond_wait() function atomically unlocks the mutex pointed to by the mutex parameter and blocks the current thread until the condition variable pointed to by 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 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.
Destroy a condition attribute.
The globus_condattr_destroy() function destroys the condition variable attribute structure pointed to by its 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.
Get callback space associated with a condition variable attributeThe 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.
Initialize a condition variable attribute.
The globus_condattr_init() function initializes the condition variable attribute structure pointed to by its 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.
Set callback space associated with a condition variable attributeThe 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.
1.8.5
