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Diffstat (limited to 'cpp/include/IceUtil/Monitor.h')
| -rw-r--r-- | cpp/include/IceUtil/Monitor.h | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/cpp/include/IceUtil/Monitor.h b/cpp/include/IceUtil/Monitor.h new file mode 100644 index 00000000000..77af7f53822 --- /dev/null +++ b/cpp/include/IceUtil/Monitor.h @@ -0,0 +1,238 @@ +// ********************************************************************** +// +// Copyright (c) 2001 +// MutableRealms, Inc. +// Huntsville, AL, USA +// +// All Rights Reserved +// +// ********************************************************************** + +#ifndef ICE_UTIL_MONITOR_H +#define ICE_UTIL_MONITOR_H + +#include <IceUtil/Config.h> +#include <IceUtil/Lock.h> +#include <IceUtil/Cond.h> + +namespace IceUtil +{ + +// +// This monitor implements the Mesa monitor semantics. That is any +// calls to notify() or notifyAll() are delayed until the monitor is +// unlocked. +// +template <class T> +class ICE_UTIL_API Monitor +{ +public: + + typedef Lock<Monitor<T> > Lock; + typedef TryLock<Monitor<T> > TryLock; + + typedef ConstLock<Monitor<T> > ConstLock; + typedef ConstTryLock<Monitor<T> > ConstTryLock; + + Monitor(); + ~Monitor(); + + // + // Note that lock/trylock & unlock in general should not be used + // directly. Instead use Lock & TryLock. + // + void lock(); + void unlock(); + void trylock(); + + void wait(); + bool timedwait(long); + void notify(); + void notifyAll(); + +private: + + // noncopyable + Monitor(const Monitor&); + void operator=(const Monitor&); + + void notifyImpl(int); + + Cond _cond; + T _mutex; + int _nnotify; +}; + +} // End namespace IceUtil + +// +// Since this monitor implements the Mesa monitor semantics calls to +// notify() or notifyAll() are delayed until the monitor is +// unlocked. This can happen either due to a call to unlock(), or a +// call to wait(). The _nnotify flag keeps track of the number of +// pending notification calls. -1 indicates a broadcast, a positive +// number indicates <n> calls to notify(). The _nnotify flag is reset +// upon initial acquisition of the monitor lock (either through a call +// to lock(), or a return from wait(). +// + +template <class T> inline +IceUtil::Monitor<T>::Monitor() : + _nnotify(0) +{ +} + +template <class T> inline +IceUtil::Monitor<T>::~Monitor() +{ +} + +template <class T> inline void +IceUtil::Monitor<T>::lock() +{ + if (_mutex.lock()) + { + // + // On the first mutex acquisition reset the number pending + // notifications. + // + _nnotify = 0; + } +} + +template <class T> inline void +IceUtil::Monitor<T>::unlock() +{ + int nnotify = _nnotify; + if (_mutex.unlock()) + { + // + // Perform any pending notifications. + // + notifyImpl(nnotify); + } +} + +template <class T> inline void +IceUtil::Monitor<T>::trylock() +{ + if (_mutex.trylock()) + { + // + // On the first mutex acquisition reset the number pending + // notifications. + // + _nnotify = 0; + } +} + +template <class T> inline void +IceUtil::Monitor<T>::wait() +{ + // + // Perform any pending notifies + // + notifyImpl(_nnotify); + + // + // Wait for a notification + // + try + { + _cond.waitImpl(_mutex); + // + // Reset the nnotify count once wait() returns. + // + } + catch(...) + { + _nnotify = 0; + throw; + } + _nnotify = 0; +} + +template <class T> inline bool +IceUtil::Monitor<T>::timedwait(long msec) +{ + // + // Perform any pending notifies. + // + notifyImpl(_nnotify); + + bool rc; + // + // Wait for a notification. + // + try + { + rc = _cond.timedwaitImpl(_mutex, msec); + + // + // Reset the nnotify count once wait() returns. + // + } + catch(...) + { + _nnotify = 0; + throw; + } + + _nnotify = 0; + return rc; +} + +template <class T> inline void +IceUtil::Monitor<T>::notify() +{ + // + // Increment the _nnotify flag, unless a broadcast has already + // been requested. + // + if (_nnotify != -1) + { + ++_nnotify; + } +} + +template <class T> inline void +IceUtil::Monitor<T>::notifyAll() +{ + // + // -1 (indicates broadcast) + // + _nnotify = -1; +} + + +template <class T> inline void +IceUtil::Monitor<T>::notifyImpl(int nnotify) +{ + // + // Zero indicates no notifies. + // + if (nnotify != 0) + { + // + // -1 means notifyAll. + // + if (nnotify == -1) + { + _cond.broadcast(); + return; + } + else + { + // + // Otherwise notify n times. + // + while (nnotify > 0) + { + _cond.signal(); + --nnotify; + } + } + } +} + +#endif |