vpThread Class Reference

#include <visp3/core/vpThread.h>

Public Types
typedef void *	Args
typedef void *	Return
typedef void *(*	Fn) (Args)
typedef pthread_t	Handle

Public Member Functions
	vpThread ()
	vpThread (vpThread::Fn fn, vpThread::Args args=NULL)
void	create (vpThread::Fn fn, vpThread::Args args=NULL)
virtual	~vpThread ()
void	join ()
Handle	getHandle ()
bool	joinable ()

Protected Attributes
Handle	m_handle
bool	m_isCreated
bool	m_isJoinable

Detailed Description

Class to represent individual threads of execution. This class implements native pthread functionalities if available, or native Windows threading capabilities if pthread is not available under Windows.

There are two examples implemented in testMutex.cpp and testThread.cpp to show how to use this class. The content of test-thread.cpp that hightlights the main functionalities of this class is given hereafter:

#include <iostream>

#include <visp3/core/vpThread.h>
#include <visp3/core/vpTime.h>

vpThread::Return myFooFunction(vpThread::Args args)
{
  (void)(args); // Avoid warning: unused parameter args
  // do stuff...
  return 0;
}

vpThread::Return myBarFunction(vpThread::Args args)
{
  (void)(args); // Avoid warning: unused parameter args
  // do stuff...
  return 0;
}

vpThread::Return myQuxFunction(vpThread::Args args)
{
  unsigned int args_ = *((unsigned int *)args);
  std::cout << "qux arg: " << args_ << std::endl;
  // do stuff...
  return 0;
}

int main()
{
  unsigned int qux_arg = 12;
  vpThread foo;
  vpThread bar((vpThread::Fn)myBarFunction);
  vpThread qux((vpThread::Fn)myQuxFunction,
               (vpThread::Args)&qux_arg); // Pass qux_arg to myQuxFunction() function

  vpTime::wait(1000); // Sleep 1s to ensure myQuxFunction() internal printings
  std::cout << "Joinable after construction:" << std::endl;
  std::cout << "foo: " << foo.joinable() << std::endl;
  std::cout << "bar: " << bar.joinable() << std::endl;
  std::cout << "qux: " << qux.joinable() << std::endl;

  foo.create((vpThread::Fn)myFooFunction);

  std::cout << "Joinable after creation:" << std::endl;
  std::cout << "foo: " << foo.joinable() << std::endl;
  std::cout << "bar: " << bar.joinable() << std::endl;
  std::cout << "qux: " << qux.joinable() << std::endl;

  if (foo.joinable())
    foo.join();
  if (bar.joinable())
    bar.join();
  if (qux.joinable())
    qux.join();

  std::cout << "Joinable after joining:" << std::endl;
  std::cout << "foo: " << foo.joinable() << std::endl;
  std::cout << "bar: " << bar.joinable() << std::endl;
  std::cout << "qux: " << qux.joinable() << std::endl;

  return 0;
}

More examples are provided in Tutorial: How to use multi-threading capabilities.

Examples:

grabRealSense.cpp, testForceTorqueAti.cpp, testMutex.cpp, testThread.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-grabber-opencv-threaded.cpp, and tutorial-grabber-v4l2-threaded.cpp.

Definition at line 36 of file vpThread.h.

Member Typedef Documentation

Args

typedef void* vpThread::Args

Definition at line 40 of file vpThread.h.

Fn

typedef void*(* vpThread::Fn) (Args)

Examples:

testMutex.cpp, testThread.cpp, testThread2.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-grabber-opencv-threaded.cpp, and tutorial-grabber-v4l2-threaded.cpp.

Definition at line 42 of file vpThread.h.

Handle

typedef pthread_t vpThread::Handle

Definition at line 43 of file vpThread.h.

Return

typedef void* vpThread::Return

Definition at line 41 of file vpThread.h.

Constructor & Destructor Documentation

vpThread() [1/2]

vpThread::vpThread ( )

inline

Default constructor that does nothing. To attach a function to this thread of execution you need to call create().

Definition at line 55 of file vpThread.h.

vpThread() [2/2]

vpThread::vpThread ( vpThread::Fn  fn, vpThread::Args  args = NULL  )

inline

Construct a thread object that represents a new joinable thread of execution. The new thread of execution calls fn passing args as arguments.

Parameters

fn	: A pointer to a function.
args	: Arguments passed to the call to fn (if any).

Definition at line 63 of file vpThread.h.

References create().

~vpThread()

virtual vpThread::~vpThread ( )

inlinevirtual

Destroy the thread.

Definition at line 98 of file vpThread.h.

References join(), and m_handle.

Member Function Documentation

create()

void vpThread::create ( vpThread::Fn  fn, vpThread::Args  args = NULL  )

inline

Creates a thread object that represents a new joinable thread of execution.

Parameters

fn	: A pointer to a function.
args	: Arguments passed to the call to fn (if any).

Examples:

testMutex.cpp, and testThread.cpp.

Definition at line 73 of file vpThread.h.

References vpException::cannotUseConstructorError, vpException::fatalError, m_handle, m_isCreated, and m_isJoinable.

Referenced by vpThread().

getHandle()

Handle vpThread::getHandle ( )

inline

Returns a value used to access implementation-specific information associated to the thread.

Definition at line 137 of file vpThread.h.

References m_handle.

join()

void vpThread::join ( )

inline

This function return when the thread execution has completed. This blocks the execution of the thread that calls this function until the function called on construction returns (if it hasn't yet).

After a call to this function, the thread object becomes non-joinable and can be destroyed safely.

See also

joinable()

Examples:

testForceTorqueAti.cpp, testThread.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-grabber-opencv-threaded.cpp, and tutorial-grabber-v4l2-threaded.cpp.

Definition at line 117 of file vpThread.h.

References m_handle, and m_isJoinable.

Referenced by ~vpThread().

joinable()

bool vpThread::joinable ( )

inline

Returns whether the thread object is joinable.

A thread object is not joinable in any of these cases:

• if it was default-constructed and create() was not called.
• if join() has been called.

See also

join()

Examples:

testThread.cpp.

Definition at line 148 of file vpThread.h.

References m_isJoinable.

Member Data Documentation

m_handle

Handle vpThread::m_handle

protected

Thread handle.

Definition at line 151 of file vpThread.h.

Referenced by create(), getHandle(), join(), and ~vpThread().

m_isCreated

bool vpThread::m_isCreated

protected

Indicates if the thread is created.

Definition at line 152 of file vpThread.h.

Referenced by create().

m_isJoinable

bool vpThread::m_isJoinable

protected

Indicates if the thread is joinable.

Definition at line 153 of file vpThread.h.

Referenced by create(), join(), and joinable().