BQueue.h

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/*******************************************************************************
 *  BQueue.h    Queue Classes
 *  T.Barnaby,  BEAM Ltd,   2014-07-23
 *  Copyright (c) 2022 All Right Reserved, Beam Ltd, https://www.beam.ltd.uk
 *  For license see LICENSE.txt at the root of the beamlib source tree.
 *******************************************************************************
 *
 * Simple thread safe queue.
 */
#ifndef BQueue_h
#define BQueue_h    1
 
#include <BTypes.h>
#include <BError.h>
#include <BList.h>
#include <BMutex.h>
#include <BCondInt.h>
 
template <class T> class BQueue : private BList<T>{
public:
            BQueue(BUInt size);
            ~BQueue();
        
    void        clear();                            
 
    BUInt       writeAvailable() const;
    BError      write(const T& v,  BTimeout timeout = BTimeoutForever);     
 
    BUInt       readAvailable() const;
    BError      read(T& v,  BTimeout timeout = BTimeoutForever);        
 
private:
    BMutex      olock;
    BUInt       osize;
    BCondInt    onumber;
};
 
// BQueueInt class
typedef BQueue<BInt32>  BQueueInt;
 
// BQueue class implementation
template <class T> BQueue<T>::BQueue(BUInt size){
    osize = size;
}
 
template <class T> BQueue<T>::~BQueue(){
}
 
template <class T> void BQueue<T>::clear(){
    olock.lock();
    BList<T>::clear();
    olock.unlock();
}
 
template <class T> BUInt BQueue<T>::writeAvailable() const{
    return osize - onumber.value();
}
 
template <class T> BUInt BQueue<T>::readAvailable() const{
    return onumber.value();
}
 
template <class T> BError BQueue<T>::write(const T& v,  BTimeout timeout){
    BError      err;
 
    if(!onumber.waitLessThanOrEqual(osize - 1, 0, timeout))
        return err.set(ErrorTimeout, "Timeout");
 
    olock.lock();
    BList<T>::queueAdd(v);
    olock.unlock();
    onumber.increment();
        
    return err;
}
 
template <class T> BError BQueue<T>::read(T& v,  BTimeout timeout){
    BError      err;
 
    if(!onumber.waitMoreThanOrEqual(1, 1, timeout))
        return err.set(ErrorTimeout, "Timeout");
 
    olock.lock();
    v = BList<T>::queueGet();
    olock.unlock();
        
    return err;
}
 
#endif