larbin源码分析--SyncFifo
//同步队列中的每个操作都需要先加锁，后解锁，以免发生同步问题。
template <class T>
class SyncFifo {
protected:
uint in, out; //队列的两个标志位，一个入口标志位，一个出口标志位
uint size; //队列长度
T **tab;
#ifdef THREAD_OUTPUT
pthread_mutex_t lock; //因为这个队列是同步的，所以有锁
pthread_cond_t nonEmpty;
#endif
public:
/* Specific constructor */
SyncFifo (uint size = std_size);
/* Destructor */
~SyncFifo ();
/* get the first object */
T *get (); //获得队列头
/* get the first object (non totally blocking)
* return NULL if there is none
*/
T *tryGet ();
/* add an object in the Fifo */
void put (T *obj); //入队
/* how many itmes are there inside ? */
int getLength (); //获取体积
};
template <class T>
SyncFifo<T>::SyncFifo (uint size) {
tab = new T*[size];
this->size = size;
in = 0;
out = 0;
mypthread_mutex_init (&lock, NULL);
mypthread_cond_init (&nonEmpty, NULL);
}
template <class T>
SyncFifo<T>::~SyncFifo () {
delete [] tab;
mypthread_mutex_destroy (&lock);
mypthread_cond_destroy (&nonEmpty);
}
template <class T>
T *SyncFifo<T>::get () {
T *tmp;
mypthread_mutex_lock(&lock);
mypthread_cond_wait(in == out, &nonEmpty, &lock);
tmp = tab[out];
out = (out + 1) % size;
mypthread_mutex_unlock(&lock);
return tmp;
}
template <class T>
T *SyncFifo<T>::tryGet () { //每次获取时都要先加锁，后解锁
T *tmp = NULL;
mypthread_mutex_lock(&lock);
if (in != out) {
// The stack is not empty
tmp = tab[out];
out = (out + 1) % size;
}
mypthread_mutex_unlock(&lock);
return tmp;
}
template <class T>
void SyncFifo<T>::put (T *obj) {
mypthread_mutex_lock(&lock);
tab[in] = obj;
if (in == out) {
mypthread_cond_broadcast(&nonEmpty);
}
in = (in + 1) % size;
if (in == out) {
T **tmp;
tmp = new T*[2*size];
for (uint i=out; i<size; i++) {
tmp[i] = tab[i];
}
for (uint i=0; i<in; i++) {
tmp[i+size] = tab[i];
}
in += size;
size *= 2;
delete [] tab;
tab = tmp;
}
mypthread_mutex_unlock(&lock);
}
template <class T>
int SyncFifo<T>::getLength () {
int tmp;
mypthread_mutex_lock(&lock);
tmp = (in + size - out) % size;
mypthread_mutex_unlock(&lock);
return tmp;
}
#endif // SYNCFIFO_H