singleton

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
#include<string.h>

pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

typedef struct _object
{
	int data;
	void* (*data_func)(void *);
}singleton;

singleton *getSingleton()
{
	static singleton * instance = NULL;
	
	
	if(NULL == instance)
	{
		pthread_mutex_lock(&lock);
		if(NULL == instance)
		{
			
			instance = (singleton *)malloc(sizeof(singleton));
			memset(instance,0,sizeof(singleton));
			return instance;
		}
		pthread_mutex_unlock(&lock);		
	}
	
	return instance;
};

void main(int args, char *argv[])
{
	singleton *single = getSingleton();
	single->data = 3;		
}