RTT::OS::Thread Class Reference

A Thread object executes user code in its own thread. More...

#include <rtt/os/Thread.hpp>

Inheritance diagram for RTT::OS::Thread:

Public Member Functions
	Thread (int scheduler, int priority, double period, const std::string &name, OS::RunnableInterface *r=0)
	Create a Thread with a given scheduler type, priority and a name.
virtual bool	run (OS::RunnableInterface *r)
	Run the functionality of one RunnableInterface object.
virtual bool	start ()
	Start the Thread.
virtual bool	stop ()
	Stop the Thread.
bool	setPeriod (Seconds s)
	Set the periodicity in Seconds.
bool	setPeriod (secs s, nsecs ns)
	Set the periodicity of this thread (seconds, nanoseconds).
bool	setPeriod (TIME_SPEC p)
	Set the periodicity of this thread.
void	getPeriod (secs &s, nsecs &ns) const
	Get the periodicity of this thread (seconds, nanoseconds).
virtual Seconds	getPeriod () const
	Get the periodicity in Seconds.
virtual nsecs	getPeriodNS () const
	Get the periodicity in nanoseconds.
virtual bool	isPeriodic () const
virtual bool	isRunning () const
	Returns whether the thread is running.
virtual bool	isActive () const
	Returns whether the thread is active.
virtual const char *	getName () const
	Read the name of this task.
virtual RTOS_TASK *	getTask ()
	Get the RTOS_TASK pointer.
virtual bool	setScheduler (int sched_type)
	Change the scheduler policy in which this thread runs.
virtual int	getScheduler () const
	Get the scheduler policy in which this thread runs.
virtual bool	setPriority (int priority)
	Set the priority of this Thread.
virtual int	getPriority () const
	The priority of this Thread.
virtual void	yield ()
	Yields (put to the back of the scheduler queue) the calling thread.
void	setMaxOverrun (int m)
int	getMaxOverrun () const
unsigned int	threadNumber () const
	The unique thread number (within the same process).
Static Public Member Functions
static void	setStackSize (unsigned int ssize)
	Sets the stack size of the threads to be created.
Protected Member Functions
void	terminate ()
	Exit and destroy the thread.
void	emergencyStop ()
virtual void	step ()
virtual void	loop ()
virtual bool	breakLoop ()
virtual bool	initialize ()
virtual void	finalize ()
Protected Attributes
int	threadnb
	Threads are given an unique number, which follows thread creation order.
Friends
void *	thread_function (void *t)

Detailed Description

A Thread object executes user code in its own thread.

If the underlying OS supports it, both period and priority can be changed after creation. When the period is 0, the loop() function is executed, when the period is greater than 0, the step() function is executed. Note: if the user does not implement loop(), it will call step() by default.

The main functions to implement are initialize(), step()/loop() and finalize(). initialize() is called when start() is called, and before the first step()/loop() and finalize() is called when stop() is called after the last step()/loop() returns.

behavior

When a period is set, step() is executed from the moment start() is called, and afterwards according to it's period. When stop() is called, it waits for the step() function to return and then stops the periodic execution.

Step() overruns are detected and the threshold to 'emergency stop' the thread can be set by setMaxOverrun(). Overruns must be accumulated 'on average' to trigger this behavior: one not overrunning step() compensates for one overrunning step().

periodic behaviour

The first invocation of start() invokes the initialize() function and runs the loop() method in the thread. When loop() returns the thread waits for another start() to execute loop() again. In that case, initialize() is not executed.

When stop() is called and the thread is still executing loop() and breakLoop() returns true (not the default), the stop() function succeeds and the finalize() method is called by stop(). If the thread was not executing loop(), stop will always call finalize() and return success.

The user must provide an implementation of breakLoop() returning true to make stop() work while loop() is being executed. stop() will fail and not execute finalize() if the thread executes loop() and breakLoop() is not reimplemented to return true.

When a RunnableInterface object is given, the above methods initialize(), loop(), breakLoop() and finalize() are called on that object instead of on the SingleThread's virtual functions.

, priorities, schedulers and stack sizes

These four parameters are the parameters that users wish to set for every thread created. All but stack size can be modified after creation, and if the OS permits it, modified even when the thread is using user code. All these parameters are passed to the underlying OS unmodified. In case an incorrect combination is made, the change may be rejected or adjusted to a close or safe value.

See also:: setPeriod, setScheduler, setPriority, setStackSize

Definition at line 115 of file Thread.hpp.

Constructor & Destructor Documentation

RTT::OS::Thread::Thread	(	int	scheduler,
		int	priority,
		double	period,
		const std::string &	name,
		OS::RunnableInterface *	r = `0`
	)

Create a Thread with a given scheduler type, priority and a name.

Parameters:

	scheduler	The scheduler, one of ORO_SCHED_RT or ORO_SCHED_OTHER.
	priority	The priority of the thread, this is interpreted by your RTOS.
	period	The period in seconds (eg 0.001) of the thread, or zero if not periodic.
	name	The name of the Thread. May be used by your OS to identify the thread.
	r	The optional RunnableInterface instance to run. If not present, the thread's own virtual functions are executed.

Member Function Documentation

virtual bool RTT::OS::Thread::breakLoop ( ) [protected, virtual]

See also:: RTT::OS::RunnableInterface::breakLoop()

Reimplemented in RTT::Activity.

virtual void RTT::OS::Thread::finalize ( ) [protected, virtual]

See also:: RTT::OS::RunnableInterface::finalize()

Reimplemented in RTT::Activity.

virtual Seconds RTT::OS::Thread::getPeriod ( ) const [virtual]

Get the periodicity in Seconds.

Return zero if non periodic.

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

virtual nsecs RTT::OS::Thread::getPeriodNS ( ) const [virtual]

Get the periodicity in nanoseconds.

Return zero if non periodic.

Implements RTT::OS::ThreadInterface.

virtual int RTT::OS::Thread::getPriority ( ) const [virtual]

The priority of this Thread.

Returns:: The priority given upon construction of this thread or set with setPriority. The returned number has to be interpreted in the current OS scheduler.

See also:: setScheduler

Implements RTT::OS::ThreadInterface.

virtual int RTT::OS::Thread::getScheduler ( ) const [virtual]

Get the scheduler policy in which this thread runs.

Returns:: An OS-specific value which represents the used scheduler.

See also:: setScheduler

Implements RTT::OS::ThreadInterface.

virtual RTOS_TASK* RTT::OS::Thread::getTask ( ) [inline, virtual]

Get the RTOS_TASK pointer.

Note:: Using this function leads to non-portable code. It is here for users which wish to tweak OS specific thread settings.

Implements RTT::OS::ThreadInterface.

Definition at line 183 of file Thread.hpp.

virtual bool RTT::OS::Thread::initialize ( ) [protected, virtual]

See also:: RTT::OS::RunnableInterface::initialize()

Reimplemented in RTT::Activity.

virtual bool RTT::OS::Thread::isActive ( ) const [virtual]

Returns whether the thread is active.

A thread is active between the invocation of start() and the invocation of stop().

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

virtual bool RTT::OS::Thread::isRunning ( ) const [virtual]

Returns whether the thread is running.

A thread is running if it is executing its loop() function or in the process of periodically calling step(). Hence for periodic threads, isRunning() == isActive() while for non-periodic threads, isRunning() is only true if isActive() and it is executing loop().

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

virtual void RTT::OS::Thread::loop ( ) [protected, virtual]

See also:: RTT::OS::RunnableInterface::loop()

Reimplemented in RTT::Activity.

virtual bool RTT::OS::Thread::run ( OS::RunnableInterface * r ) [virtual]

Run the functionality of one RunnableInterface object.

Only one RunnableInterface object can be run, the old one is disconnected.

Parameters:

r

The object to run or zero to clear.

Returns:: true if accepted, false if the thread is running.

Implements RTT::OS::ThreadInterface.

bool RTT::OS::Thread::setPeriod ( Seconds new_period ) [virtual]

Set the periodicity in Seconds.

Parameters:

new_period

A positive number expressing the period

Returns:: true if it was accepted, false otherwise.

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

virtual bool RTT::OS::Thread::setPriority ( int priority ) [virtual]

Set the priority of this Thread.

Parameters:

priority

The priority given upon construction of this thread. It has to be interpreted in the current OS scheduler.

See also:: setScheduler

Implements RTT::OS::ThreadInterface.

virtual bool RTT::OS::Thread::setScheduler ( int sched_type ) [virtual]

Change the scheduler policy in which this thread runs.

Parameters:

sched_type

An OS-specific value which selects a scheduler. Orocos requires that these two values are available:

ORO_SCHED_RT: Hint the OS that this thread should be scheduled as a priority or real-time process.
ORO_SCHED_OTHER: Hint the OS that this thread should not be scheduled as a priority or real-time process.

Your OS can in addition provide other sched_type's which map more naturally to the schedulers present. If your OS does not make a distinction between real-time and other, both values may map to the same scheduler type.

Returns:: true if the change could be made.

Implements RTT::OS::ThreadInterface.

static void RTT::OS::Thread::setStackSize ( unsigned int ssize ) [static]

Sets the stack size of the threads to be created.

This value is suggestive and may be altered or ignored by your operating system. Use zero to use the system's default.

Parameters:

ssize

the size of the stack in bytes

virtual bool RTT::OS::Thread::start ( ) [virtual]

Start the Thread.

Postcondition:: initialize() is called first; The Thread is running

Returns:: true if the function did succeed. false otherwise.

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

virtual void RTT::OS::Thread::step ( ) [protected, virtual]

See also:: RTT::OS::RunnableInterface::step()

Reimplemented in RTT::Activity.

virtual bool RTT::OS::Thread::stop ( ) [virtual]

Stop the Thread.

Postcondition:: The Thread is no longer being run; finalize() is called when the Thread is stopped.

Returns:: true if the function did succeed. false otherwise.

Implements RTT::OS::ThreadInterface.

Reimplemented in RTT::Activity.

void RTT::OS::Thread::terminate ( ) [protected]

Exit and destroy the thread.

Precondition:: this is only called from within the destructor.

Postcondition:: the thread does no longer exist.

Member Data Documentation

int RTT::OS::ThreadInterface::threadnb [protected, inherited]

Threads are given an unique number, which follows thread creation order.

See also:: OS::threads

Definition at line 191 of file ThreadInterface.hpp.

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

rtt/os/Thread.hpp

RTT::OS::Thread Class Reference

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

behavior

periodic behaviour

, priorities, schedulers and stack sizes

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation