红包

application/common/library/RedpacketLua.php

@@ -0,0 +1,105 @@
+<?php
+
+namespace app\common\library;
+
+class RedpacketLua
+{
+    /**
+     * 抢红包Lua脚本
+     * 保证原子性操作，防止超抢
+     */
+    public static function grabRedpacketScript()
+    {
+        return <<<LUA
+-- KEYS[1]: 红包key, KEYS[2]: 用户集合key, KEYS[3]: 用户ID
+-- ARGV[1]: 当前时间
+
+local redpacketKey = KEYS[1]
+local userSetKey = KEYS[2]
+local userId = KEYS[3]
+local currentTime = tonumber(ARGV[1])
+
+-- 检查红包是否存在
+local redpacketData = redis.call('HGETALL', redpacketKey)
+if not redpacketData or #redpacketData == 0 then
+    return {0, "红包不存在"}
+end
+
+-- 将哈希数据转为table
+local redpacket = {}
+for i = 1, #redpacketData, 2 do
+    redpacket[redpacketData[i]] = redpacketData[i + 1]
+end
+
+-- 检查红包状态
+local status = tonumber(redpacket['status'])
+local startTime = tonumber(redpacket['start_time'])
+local endTime = tonumber(redpacket['end_time'])
+
+if status == 0 then
+    if currentTime < startTime then
+        return {0, "红包还未开始"}
+    else
+        -- 更新状态为进行中
+        redis.call('HSET', redpacketKey, 'status', 1)
+        status = 1
+    end
+end
+
+if status ~= 1 then
+    return {0, "红包已结束"}
+end
+
+if currentTime > endTime then
+    redis.call('HSET', redpacketKey, 'status', 2)
+    return {0, "红包已结束"}
+end
+
+-- 检查是否已经抢过
+local hasGrabbed = redis.call('SISMEMBER', userSetKey, userId)
+if hasGrabbed == 1 then
+    return {0, "已经抢过该红包"}
+end
+
+-- 检查是否还有剩余
+local leftAmount = tonumber(redpacket['left_amount'])
+local leftCount = tonumber(redpacket['left_count'])
+
+if leftCount <= 0 or leftAmount <= 0 then
+    return {0, "红包已抢完"}
+end
+
+-- 计算红包金额
+local amount = 0
+if leftCount == 1 then
+    -- 最后一个红包，获得剩余所有金额
+    amount = leftAmount
+else
+    -- 随机算法：二倍均值法，保证公平性
+    local maxAmount = leftAmount / leftCount * 2
+    amount = math.random(1, math.floor(maxAmount * 100)) / 100
+    -- 确保金额不会超过剩余金额
+    if amount > leftAmount then
+        amount = leftAmount
+    end
+end
+
+-- 更新红包数据
+local newLeftAmount = leftAmount - amount
+local newLeftCount = leftCount - 1
+
+redis.call('HSET', redpacketKey, 'left_amount', newLeftAmount)
+redis.call('HSET', redpacketKey, 'left_count', newLeftCount)
+
+-- 标记用户已抢
+redis.call('SADD', userSetKey, userId)
+
+-- 如果抢完了，更新状态
+if newLeftCount == 0 then
+    redis.call('HSET', redpacketKey, 'status', 2)
+end
+
+return {1, tostring(amount)}
+LUA;
+    }
+}