Condition Class Reference

#include <Condition.h>

List of all members.

Public Member Functions
void	broadcast ()
	Condition ()
void	signal ()
void	wait (Mutex &mutex)
void	wait (Mutex &mutex, unsigned int maxTime)
virtual	~Condition ()
Private Attributes
TCondition *	m_Condition
bool	m_SignalArrived
Mutex	m_SignalArrivedMutex

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Detailed Description

A synchronization object for one-to-one or one-to-many control events.

The Condition class provides a synchonization object for one-to-one and one-to-many control events. Using this class, it is possible to pause the execution of a thread until it gets a signal from another thread to continue. This signal can be sent to only a single thread (one-to-one event) via signal or to all threads waiting for the condition object (one-to-many) via broadcast.

Note that sometimes signals are issued by the operating system and not only by other threads. So the criterion you are waiting for may not be satisfied. However, this can be handled using a loop:

    Condition condition;
    bool criterion;
    Mutex mutex;
    mutex.lock();
    ...
    while( !criterion){
      condition.wait(mutex);
    }
    ...
    mutex.unlock();

The signaling thread should use code like the following:

    criterion = true;
    condition.signal();   // or "condition.broadcast()"

Definition at line 53 of file Condition.h.

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Constructor & Destructor Documentation

Condition::Condition

(

)

Default constructor. Creates a new platform-dependent condition object.

Definition at line 22 of file Condition.cpp.

Condition::~Condition

(

)

[virtual]

Destructor. Destroys the instance and releases all associated system resources.

Definition at line 30 of file Condition.cpp.

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Member Function Documentation

void Condition::broadcast

(

)

Issue a signal and wake up all threads waiting for this condition. This is useful for a one-to-many control event.

Definition at line 93 of file Condition.cpp.

void Condition::signal

(

)

Issue a signal and wake up a single thread waiting for this condition. This is useful for a one-to-one control event.

Definition at line 84 of file Condition.cpp.

void Condition::wait

(

Mutex &

mutex

)

Wait for a signal. Pauses the thread, unlock's the given mutex and waits for a signal before the execution is continued.

Parameters:

mutex

Mutex that is unlocked until the thread wakes up again

Definition at line 37 of file Condition.cpp.

void Condition::wait	(	Mutex &	mutex,
		unsigned int	maxTime
	)

Wait for a signal until a given maximum time has passed

Parameters:

maxTime

Maximal wait time [ms]

See also:

wait( Mutex& )

Definition at line 56 of file Condition.cpp.

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Member Data Documentation

TCondition* Condition::m_Condition [private]

Platform-dependent condition representation.

Definition at line 103 of file Condition.h.

bool Condition::m_SignalArrived [private]

This variable is set to true when a signal arrives. It serves as a reminder in the case that a signal arrives before a process starts waiting on it. After every wait call this variable will be set to false.

Definition at line 109 of file Condition.h.

Mutex Condition::m_SignalArrivedMutex [private]

This mutex is needed for locking the condition while the variable m_SignalArrived is modified and read by another process. Without this mutex it would be possible that signals arrive before a process starts waiting on them.

Definition at line 116 of file Condition.h.

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

• Condition.h
• Condition.cpp