barrier/mt/CCondVar.h

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#ifndef CCONDVAR_H
#define CCONDVAR_H
#include "CMutex.h"
#include "BasicTypes.h"
class CStopwatch;
//! Generic condition variable
/*!
This class provides functionality common to all condition variables
but doesn't provide the actual variable storage. A condition variable
is a multiprocessing primitive that can be waited on. Every condition
variable has an associated mutex.
*/
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class CCondVarBase {
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public:
/*!
\c mutex must not be NULL. All condition variables have an
associated mutex. The mutex needn't be unique to one condition
variable.
*/
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CCondVarBase(CMutex* mutex);
~CCondVarBase();
//! @name manipulators
//@{
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//! Lock the condition variable's mutex
/*!
Lock the condition variable's mutex. The condition variable should
be locked before reading or writing it. It must be locked for a
call to wait(). Locks are not recursive; locking a locked mutex
will deadlock the thread.
*/
void lock() const;
//! Unlock the condition variable's mutex
void unlock() const;
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//! Signal the condition variable
/*!
Wake up one waiting thread, if there are any. Which thread gets
woken is undefined.
*/
void signal();
//! Signal the condition variable
/*!
Wake up all waiting threads, if any.
*/
void broadcast();
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//@}
//! @name accessors
//@{
//! Wait on the condition variable
/*!
Wait on the condition variable. If \c timeout < 0 then wait until
signalled, otherwise up to \c timeout seconds or until signalled,
whichever comes first. Returns true if the object was signalled
during the wait, false otherwise.
The proper way to wait for a condition is:
\code
cv.lock();
while (cv-expr) {
cv.wait();
}
cv.unlock();
\endcode
where \c cv-expr involves the value of \c cv and is false when the
condition is satisfied.
(cancellation point)
*/
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bool wait(double timeout = -1.0) const;
//! Wait on the condition variable
/*!
Same as \c wait(double) but use \c timer to compare against \timeout.
Since clients normally wait on condition variables in a loop, clients
can use this to avoid recalculating \c timeout on each iteration.
Passing a stopwatch with a negative \c timeout is pointless (it will
never time out) but permitted.
(cancellation point)
*/
bool wait(CStopwatch& timer, double timeout) const;
//! Get the mutex
/*!
Get the mutex passed to the c'tor.
*/
CMutex* getMutex() const;
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//@}
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private:
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void init();
void fini();
// not implemented
CCondVarBase(const CCondVarBase&);
CCondVarBase& operator=(const CCondVarBase&);
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private:
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CMutex* m_mutex;
void* m_cond;
#if WINDOWS_LIKE
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enum { kSignal, kBroadcast };
mutable UInt32 m_waitCount;
CMutex m_waitCountMutex;
#endif
};
//! Condition variable
/*!
A condition variable with storage for type \c T.
*/
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template <class T>
class CCondVar : public CCondVarBase {
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public:
//! Initialize using \c value
CCondVar(CMutex* mutex, const T& value);
//! Initialize using another condition variable's value
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CCondVar(const CCondVar&);
~CCondVar();
//! @name manipulators
//@{
//! Assigns the value of \c cv to this
/*!
Set the variable's value. The condition variable should be locked
before calling this method.
*/
CCondVar& operator=(const CCondVar& cv);
//! Assigns \c value to this
/*!
Set the variable's value. The condition variable should be locked
before calling this method.
*/
CCondVar& operator=(const T& v);
//@}
//! @name accessors
//@{
//! Get the variable's value
/*!
Get the variable's value. The condition variable should be locked
before calling this method.
*/
operator const T&() const;
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//@}
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private:
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T m_data;
};
template <class T>
inline
CCondVar<T>::CCondVar(
CMutex* mutex,
const T& data) :
CCondVarBase(mutex),
m_data(data)
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{
// do nothing
}
template <class T>
inline
CCondVar<T>::CCondVar(
const CCondVar& cv) :
CCondVarBase(cv.getMutex()),
m_data(cv.m_data)
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{
// do nothing
}
template <class T>
inline
CCondVar<T>::~CCondVar()
{
// do nothing
}
template <class T>
inline
CCondVar<T>&
CCondVar<T>::operator=(
const CCondVar<T>& cv)
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{
m_data = cv.m_data;
return *this;
}
template <class T>
inline
CCondVar<T>&
CCondVar<T>::operator=(
const T& data)
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{
m_data = data;
return *this;
}
template <class T>
inline
CCondVar<T>::operator const T&() const
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{
return m_data;
}
// force instantiation of these common types
template class CCondVar<bool>;
template class CCondVar<SInt32>;
#endif