做商品生成訂單的時候經(jīng)常需要唯一標識翩活，模仿一下雪花算法的oc版本。
首先聲明.h文件中引入c語言文件
#ifndef TDSnowflake_h
#define TDSnowflake_h
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <sched.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <errno.h>
#include <time.h>
#include <stdint.h>
#include <sys/time.h>
#endif /* TDSnowflake_h */
struct globle {
int global_int:12;
uint64_t last_stamp;
int workid;
int seqid;
};
void set_workid(int workid);
pid_t gettid( void );
uint64_t get_curr_ms(void);
uint64_t wait_next_ms(uint64_t lastStamp);
int atomic_incr(int id);
uint64_t get_unique_id(void);
.m文件中實現(xiàn)聲明的生成19位隨機值的方法
#include "TDSnowflake.h"
struct globle g_info;
void set_workid(int workid)
{
g_info.workid = workid;
}
pid_t gettid( void )
{
return syscall( SYS_gettid );
}
uint64_t get_curr_ms()
{
struct timeval time_now;
gettimeofday(&time_now,NULL);
uint64_t ms_time=time_now.tv_sec*1000+time_now.tv_usec/1000;
return ms_time;
}
uint64_t wait_next_ms(uint64_t lastStamp)
{
uint64_t cur = 0;
do {
cur = get_curr_ms();
} while (cur <= lastStamp);
return cur;
}
int atomic_incr(int id)
{
__sync_add_and_fetch( &id, 1 );
return id;
}
uint64_t get_unique_id()
{
uint64_t uniqueId=0;
uint64_t nowtime = get_curr_ms();
uniqueId = nowtime<<22;
uniqueId |=(g_info.workid&0x3ff)<<12;
if (nowtime <g_info.last_stamp)
{
perror("error");
exit(-1);
}
if(nowtime==g_info.last_stamp){
g_info.seqid = atomic_incr(g_info.seqid)&(-1L ^ (-1L << 12L));
if(g_info.seqid==0){
nowtime = wait_next_ms(g_info.last_stamp);
}
}else{g_info.seqid = 0;}
g_info.last_stamp = nowtime;
uniqueId |=g_info.seqid;
return uniqueId;
}
