rclcpp::GuardCondition Class Reference

A condition that can be waited on in a single wait set and asynchronously triggered. More...

#include <rclcpp/guard_condition.hpp>

Collaboration diagram for rclcpp::GuardCondition:

Public Member Functions
RCLCPP_PUBLIC	GuardCondition (const rclcpp::Context::SharedPtr &context=rclcpp::contexts::get_global_default_context(), rcl_guard_condition_options_t guard_condition_options=rcl_guard_condition_get_default_options())
	Construct the guard condition, optionally specifying which Context to use. More...
RCLCPP_PUBLIC rcl_guard_condition_t &	get_rcl_guard_condition ()
	Return the underlying rcl guard condition structure.
RCLCPP_PUBLIC const rcl_guard_condition_t &	get_rcl_guard_condition () const
	Return the underlying rcl guard condition structure.
RCLCPP_PUBLIC void	trigger ()
	Signal that the condition has been met, notifying both the wait set and listeners, if any. More...
RCLCPP_PUBLIC bool	exchange_in_use_by_wait_set_state (bool in_use_state)
	Exchange the "in use by wait set" state for this guard condition. More...
RCLCPP_PUBLIC void	add_to_wait_set (rcl_wait_set_t &wait_set)
	Adds the guard condition to a waitset. More...
RCLCPP_PUBLIC void	set_on_trigger_callback (std::function< void(size_t)> callback)
	Set a callback to be called whenever the guard condition is triggered. More...

Protected Attributes
rcl_guard_condition_t	rcl_guard_condition_
std::atomic< bool >	in_use_by_wait_set_ {false}
std::recursive_mutex	reentrant_mutex_
std::function< void(size_t)>	on_trigger_callback_ {nullptr}
size_t	unread_count_ {0}
void *	wait_set_ {nullptr}

Detailed Description

A condition that can be waited on in a single wait set and asynchronously triggered.

Definition at line 31 of file guard_condition.hpp.

Constructor & Destructor Documentation

GuardCondition()

rclcpp::GuardCondition::GuardCondition ( const rclcpp::Context::SharedPtr &  context = rclcpp::contexts::get_global_default_context(), rcl_guard_condition_options_t  guard_condition_options = rcl_guard_condition_get_default_options()  )

explicit

Construct the guard condition, optionally specifying which Context to use.

Parameters

[in]	context	Optional custom context to be used. Defaults to using the global default context singleton. Shared ownership of the context is held with the guard condition until destruction.
[in]	guard_condition_options	Optional guard condition options to be used. Defaults to using the default guard condition options.

Exceptions

std::invalid_argument	if the context is nullptr.
rclcpp::exceptions::RCLError	based exceptions when underlying rcl functions fail.

Definition at line 25 of file guard_condition.cpp.

References rcl_guard_condition_init(), and RCL_RET_OK.

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Member Function Documentation

add_to_wait_set()

void rclcpp::GuardCondition::add_to_wait_set

(

rcl_wait_set_t &

wait_set

)

Adds the guard condition to a waitset.

This function is thread-safe.

Parameters

[in]

wait_set

pointer to a wait set where to add the guard condition

Definition at line 95 of file guard_condition.cpp.

References exchange_in_use_by_wait_set_state(), RCL_RET_OK, and rcl_wait_set_add_guard_condition().

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exchange_in_use_by_wait_set_state()

bool rclcpp::GuardCondition::exchange_in_use_by_wait_set_state

(

bool

in_use_state

)

Exchange the "in use by wait set" state for this guard condition.

This is used to ensure this guard condition is not used by multiple wait sets at the same time.

Parameters

[in]

in_use_state

the new state to exchange into the state, true indicates it is now in use by a wait set, and false is that it is no longer in use by a wait set.

Returns

the previous state.

Definition at line 89 of file guard_condition.cpp.

Referenced by add_to_wait_set().

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set_on_trigger_callback()

void rclcpp::GuardCondition::set_on_trigger_callback

(

std::function< void(size_t)>

callback

)

Set a callback to be called whenever the guard condition is triggered.

The callback receives a size_t which is the number of times the guard condition was triggered since the last time this callback was called. Normally this is 1, but can be > 1 if the guard condition was triggered before any callback was set.

Calling it again will clear any previously set callback.

This function is thread-safe.

If you want more information available in the callback, like the guard condition or other information, you may use a lambda with captures or std::bind.

Parameters

[in]

callback

functor to be called when the guard condition is triggered

Definition at line 115 of file guard_condition.cpp.

trigger()

void rclcpp::GuardCondition::trigger

(

)

Signal that the condition has been met, notifying both the wait set and listeners, if any.

This function is thread-safe, and may be called concurrently with waiting on this guard condition in a wait set.

Exceptions

rclcpp::exceptions::RCLError

based exceptions when underlying rcl functions fail.

Definition at line 70 of file guard_condition.cpp.

References RCL_RET_OK, and rcl_trigger_guard_condition().

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The documentation for this class was generated from the following files:

• rclcpp/include/rclcpp/guard_condition.hpp
• rclcpp/src/rclcpp/guard_condition.cpp