DDS::WaitSet Class Reference

A WaitSet maintains a set of Condition objects and allows the application to wait until one or more of them have a trigger_value of TRUE. More...

Public Member Functions
ReturnCode_t	attach_condition (Condition &a_condition)
	Adds the condition c to the WaitSet ws. More...
ReturnCode_t	detach_condition (Condition &a_condition)
	Removes a condition c from WaitSet ws. More...
ReturnCode_t	wait (ConditionSeq &active_conditions, const Duration_t &timeout)
	Causes the controlling thread to block until an attached condition is triggered or timeout elapses. More...
ReturnCode_t	get_conditions (ConditionSeq &attached_conditions)
	Retrieves the current list of attached conditions. More...

Detailed Description

A WaitSet maintains a set of Condition objects and allows the application to wait until one or more of them have a trigger_value of TRUE.

Multiple conditions may be attached to a WaitSet. A WaitSet is created by a call to WaitSet__alloc(), and destroyed with a call to WaitSet__free().

Member Function Documentation

ReturnCode_t DDS::WaitSet::attach_condition

(

Condition &

a_condition

)

Adds the condition c to the WaitSet ws.

If another thread is currently 'waiting' on the WaitSet, this newly added condition will unblock that thread if its trigger_value is TRUE.

ReturnCode_t DDS::WaitSet::detach_condition

(

Condition &

a_condition

)

Removes a condition c from WaitSet ws.

If the condition is not attached to the WaitSet, the error RETCODE_PRECONDITION_NOT_MET will be returned.

ReturnCode_t DDS::WaitSet::get_conditions

(

ConditionSeq &

attached_conditions

)

Retrieves the current list of attached conditions.

Populates the attached_conditions sequence. The application is responsible for freeing the memory contained in the sequence.

ReturnCode_t DDS::WaitSet::wait	(	ConditionSeq &	active_conditions,
		const Duration_t &	timeout
	)

Causes the controlling thread to block until an attached condition is triggered or timeout elapses.

A return value of RETCODE_OK indicates that one or more of the attached conditions evaluated to TRUE. Those 'active' conditions are included in the 'out' parameter active_conditions.

A return value of RETCODE_TIMEOUT indicates that the timeout period elapsed without any of the conditions evaluating to TRUE.

Note

The application is responsible for clearing the memory contained in active_conditions upon return.