public class CouponService {
private JedisPool jedisPool;
public CouponService(JedisPool jedisPool) {
this.jedisPool = jedisPool;
}
public boolean grabCoupon(String couponId, String userId, int limit) {
Jedis jedis = null;
try {
jedis = jedisPool.getResource();
String lockKey = "lock:c" + couponId;
String counterKey = "c" + couponId + ":counter";
String usersKey = "c" + couponId + ":users";
// Add lock
RedisLock lock = new RedisLock(jedisPool);
if (!lock.acquire(lockKey, 200, 5000)) {
throw new RuntimeException("Capture lock failed");
}
// Check whether the coupon has been snatched
int total = Integer.parseInt(jedis.hget(couponId, "total"));
int used = Integer.parseInt(jedis.hget(couponId, "used"));
if (used >= total) {
return false;
}
// The counter is increased by itself
int count = jedis.incr(counterKey).intValue();
if (count > limit) {
return false;
}
// The rush is successful and the user information is recorded
jedis.hincrBy(couponId, "used", 1);
jedis.sadd(usersKey, userId);
return true;
} finally {
// Release the lock
if (jedis != null) {
jedis.close();
}
}
}
}
