RingBuffer队列多线程应用

队列作为经典的数据结构，应用非常广泛，比如：消息队列FIFO进行相应处理。在实现过程中，可以采用链表、数组等存储结构。而RingBuffer环形队列，通过固定长度循环存储数据，在使用中无需再进行内存分配，不容易形成内存碎片，且进、出队列的时间为O(1)，因此有着非常广泛的应用。相关内容可以参见：

http://en.wikipedia.org/wiki/Circular_buffer

在工作中，在证券行情接入、处理时，可以采用RingBuffer存放的数据对象。
实现代码如下：

#ifndef __RINGBUFFER_H
#define __RINGBUFFER_H

#include "stockquote.h"

#define RING_BUFFER_SIZE 500

typedef struct T_RING_BUFFER{
	int size;   //the ringbuffer size
	int start;  //the start pointer
	int count;  //elements count
	T_STOCKQUOTE *elements;
} T_RING_BUFFER, *PT_RING_BUFFER;

void
InitRingBuffer(T_RING_BUFFER *rb, int size);

int 
IsRbFull(T_RING_BUFFER *rb);

int
IsRbEmpty(T_RING_BUFFER *rb);

void
RbWrite(T_RING_BUFFER *rb, T_STOCKQUOTE *e);

void
RbRead(T_RING_BUFFER *rb, T_STOCKQUOTE *e);

void
DelRingBuffer(T_RING_BUFFER *rb);
#endif

void
InitRingBuffer(T_RING_BUFFER *rb, int size)
{
	int idx;
	rb->size = size;
	rb->start = 0;
	rb->count = 0;
	rb->elements = (T_STOCKQUOTE *) malloc(rb->size * sizeof(T_STOCKQUOTE));

	memset(rb->elements, 0 , size * sizeof(T_STOCKQUOTE));
	
}

int 
IsRbFull(T_RING_BUFFER *rb)
{
	return rb->count == rb->size;
}

int
IsRbEmpty(T_RING_BUFFER *rb)
{
	return rb->count == 0;
}

void
RbWrite(T_RING_BUFFER *rb, T_STOCKQUOTE *e)
{
	int end = (rb->start + rb->count) % rb->size;
	rb->elements[end] = *e;
	if (rb->count == rb->size)
		rb->start = (rb->start + 1) % rb->size;
	else
		++rb->count;
}

void
RbRead(T_RING_BUFFER *rb, T_STOCKQUOTE *e)
{
	*e = rb->elements[rb->start];
	rb->start = (rb->start + 1) % rb->size;
	--rb->count;
}

void
DelRingBuffer(T_RING_BUFFER *rb)
{
	free(rb->elements);
	free(rb);
}

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "ringbuffer.h" 
#include "stockquote.h"

#define PRONUM 5 

void *producer(void *args);
void *consumer(void *args);

pthread_mutex_t *mutex;
pthread_cond_t *notFull, *notEmpty;


int
main(int argc, char *argv[])
{

	pthread_t proc[PRONUM];
	pthread_t cons;

	T_RING_BUFFER *rb;

	int count = 0;

	mutex = (pthread_mutex_t *) malloc(sizeof(pthread_mutex_t));

	pthread_mutex_init(mutex, NULL);

	notFull = (pthread_cond_t *) malloc(sizeof(pthread_cond_t));

	pthread_cond_init(notFull, NULL);

	notEmpty = (pthread_cond_t *) malloc(sizeof(pthread_cond_t));

	pthread_cond_init(notEmpty, NULL);

	rb = (T_RING_BUFFER *) malloc(sizeof(T_RING_BUFFER));

	InitRingBuffer(rb, RING_BUFFER_SIZE);


	for (count = 0; count < PRONUM; count++)
	{
		pthread_create(&proc[count], NULL, producer, rb);
	}
	
	pthread_create(&cons, NULL, consumer, rb);


	for (count = 0; count < PRONUM; count++)
	{
		printf("join return :%dn", pthread_join(proc[count], NULL));
	}


	printf("wait for procn");

	pthread_join(cons, NULL);

	printf("wait for consn");

	printf("==========wait for thread finished.n");

	DelRingBuffer(rb);

	pthread_mutex_destroy(mutex);
	pthread_cond_destroy(notFull);
	pthread_cond_destroy(notEmpty);

	return 0;
}


void *
producer(void* q)
{

	int NUM = 100000;

	printf("in producern");
	T_RING_BUFFER *rb;

	int i;

	rb = (T_RING_BUFFER *)q;

	while(NUM--)	
	{		
		pthread_mutex_lock(mutex);
		
		while(IsRbFull(rb))
		{
			pthread_cond_wait(notFull, mutex);
		}
		
		T_STOCKQUOTE is;
		is.number = 10;
		RbWrite(rb, &is);
		
		pthread_mutex_unlock(mutex);
		pthread_cond_signal(notEmpty);
	
	}

	return NULL;
}

void *
consumer(void *q)
{
	long long get_num = 0;

	printf("in consumern");
	T_RING_BUFFER *rb;
	
	int i;
	
	rb = (T_RING_BUFFER *)q;

	while(get_num < (100000 * PRONUM) )
	{
		pthread_mutex_lock(mutex);
		while(IsRbEmpty(rb))
		{
			pthread_cond_wait(notEmpty, mutex);
		}
		
		T_STOCKQUOTE s;
		RbRead(rb, &s);
		get_num++;		
		pthread_mutex_unlock(mutex);
		pthread_cond_signal(notFull);
		
	}

	return NULL;
}

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