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//
// Copyright (c) ZeroC, Inc. All rights reserved.
//
#ifndef ICE_UTIL_LOCK_H
#define ICE_UTIL_LOCK_H
#include <IceUtil/Config.h>
#include <IceUtil/ThreadException.h>
namespace IceUtil
{
//
// Forward declarations.
//
class Cond;
// LockT and TryLockT are the preferred construct to lock/tryLock/unlock
// simple and recursive mutexes. You typically allocate them on the
// stack to hold a lock on a mutex.
// LockT and TryLockT are not recursive: you cannot acquire several times
// in a row a lock with the same Lock or TryLock object.
//
// We must name this LockT instead of Lock, because otherwise some
// compilers (such as Sun C++ 5.4) have problems with constructs
// such as:
//
// class Foo
// {
// // ...
// typedef Lock<Mutex> Lock;
// }
//
template <typename T>
class LockT
{
public:
LockT(const T& mutex) :
_mutex(mutex)
{
_mutex.lock();
_acquired = true;
}
~LockT()
{
if (_acquired)
{
_mutex.unlock();
}
}
void acquire() const
{
if (_acquired)
{
throw ThreadLockedException(__FILE__, __LINE__);
}
_mutex.lock();
_acquired = true;
}
bool tryAcquire() const
{
if (_acquired)
{
throw ThreadLockedException(__FILE__, __LINE__);
}
_acquired = _mutex.tryLock();
return _acquired;
}
void release() const
{
if (!_acquired)
{
throw ThreadLockedException(__FILE__, __LINE__);
}
_mutex.unlock();
_acquired = false;
}
bool acquired() const
{
return _acquired;
}
protected:
// TryLockT's contructor
LockT(const T& mutex, bool) :
_mutex(mutex)
{
_acquired = _mutex.tryLock();
}
private:
// Not implemented; prevents accidental use.
//
LockT(const LockT&);
LockT& operator=(const LockT&);
const T& _mutex;
mutable bool _acquired;
friend class Cond;
};
//
// Must be named TryLockT, not TryLock. See the comment for LockT for
// an explanation.
//
template <typename T>
class TryLockT : public LockT<T>
{
public:
TryLockT(const T& mutex) :
LockT<T>(mutex, true)
{}
};
} // End namespace IceUtil
#endif
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