99 lines
1.9 KiB
C++
99 lines
1.9 KiB
C++
/* lock.h */
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/*
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* Copyright information and license terms for this software can be
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* found in the file LICENSE that is included with the distribution
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*/
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/**
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* @author mrk
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*/
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#ifndef LOCK_H
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#define LOCK_H
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#include <stdexcept>
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#include <epicsMutex.h>
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#include <shareLib.h>
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#include <pv/noDefaultMethods.h>
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/* This is based on item 14 of
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* Effective C++, Third Edition, Scott Meyers
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*/
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// TODO reference counting lock to allow recursions
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namespace epics { namespace pvData {
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typedef epicsMutex Mutex;
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/**
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* @brief A lock for multithreading
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*
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* This is based on item 14 of
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* * Effective C++, Third Edition, Scott Meyers
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*/
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class epicsShareClass Lock : private NoDefaultMethods {
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public:
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/**
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* Constructor
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* @param m The mutex for the facility being locked.
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*/
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explicit Lock(Mutex &m)
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: mutexPtr(m), locked(true)
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{ mutexPtr.lock();}
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/**
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* Destructor
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* Note that destructor does an automatic unlock.
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*/
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~Lock(){unlock();}
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/**
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* Take the lock
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* Recursive locks are supported but each lock must be matched with an unlock.
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*/
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void lock()
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{
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if(!locked)
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{
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mutexPtr.lock();
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locked = true;
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}
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}
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/**
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* release the lock.
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*/
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void unlock()
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{
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if(locked)
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{
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mutexPtr.unlock();
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locked=false;
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}
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}
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/**
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* If lock is not held take the lock.
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* @return (false,true) if caller (does not have, has) the lock.
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*/
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bool tryLock()
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{
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if(locked) return true;
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if(mutexPtr.tryLock()) {
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locked = true;
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return true;
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}
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return false;
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}
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/**
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* See if caller has the lock,
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* @return (false,true) if caller (does not have, has) the lock.
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*/
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bool ownsLock() const{return locked;}
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private:
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Mutex &mutexPtr;
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bool locked;
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};
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}}
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#endif /* LOCK_H */
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