Shulou(Shulou.com)06/01 Report--

Redis Collection introduction "> this article shares with you a detailed introduction of the redis production lottery function. I believe that most people have not yet learned this skill. In order to make you understand better, I have summarized the following content for you. Without saying much, let's read on.

Introduction to Redis Collection

Redis collection data type, the function is very powerful. When it comes to sets, you may think of sets in high school math. In fact, they meant the same thing. Many strings (elements) can be stored in the Redis collection. Redis supports up to 2 to the power of 32 minus 1 element, but the elements in the collection are unique and there will be no repetition. Like sets in mathematics, Redis supports intersection, union, and difference sets.

Many interesting functions can be accomplished with it. The most common is the tag function. Maybe A users' tags are "animation", "sports" and "two-dimensional", while B users' tags are "sports", "travel" and "basketball". Then, using the union of collections, you can know what their common label is. In addition, when the system knows the user's tag, it can recommend relevant advertisements or products to them. In addition, there are many interesting functions that it can also implement. Today, let's take a look at how to use Reids to implement raffle.

SRandMember 、 sPop

The functions of the two commands are very similar, returning an element value from the collection. The difference is that sRandMember does not delete the returned elements from the collection, but sPop does. These two commands can implement different raffle algorithms respectively.

For example, there are 100 elements in the collection, with values ranging from the number 1 to the number 100. If we define that the number 1 is drawn, it means winning the lottery.

With sRandMember, no matter how many times you have smoked before, the probability of winning the next one is 1%. However, if sPop is used, the probability of each draw is different. The probability of the first person's lottery is 1%. When the first person fails, the probability of the second person's lottery is 1big 99, and so on.

Realization of lottery function

In fact, there are only two steps to realize the raffle function, first set the raffle probability, that is, add elements to the collection, and then start the raffle.

Set the raffle probability. The pseudo code is as follows:

/ * $key collection key name * $cnt collection element number * / function setProb ($key, $cnt) {for ($I = 1; $I sAdd ($key, $I);}}

Raffle, the pseudo code is as follows:

/ * string $key collection key name * int $stand less than or equal to this number means lottery * int $type lottery algorithm. 1 means using sRandMember,2 * using sPop * / function draw ($key, $stand, $type = 1) {if ($type = = 1) {$number = $redis- > sRandMember ($key);} else {$number = $redis- > sPop ($key);} return $number < $stand;}

Note that stand is used to set the probability. For example, if there are 10000 elements in the set, if stand is set to 10, the probability is 10, 000. When the element value returned by the redis collection is less than or equal to that value, it is a draw.

The collection of Redis can also perform other interesting functions, such as counting daily visits to ip, counting active users, and so on. You can use your imagination to accomplish more interesting functions.

The above is the specific introduction of the lottery function of redis production, the content is more comprehensive, and I also believe that there are some methods that we may see or use in our daily work. Through this article, I hope you can gain more.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.