订单抢购防超卖Lua脚本
该方法主要用来防止超卖,将Compare And Set使用Lua脚本封装,传入Redis执行.
因为Redis是单线程执行,所以Lua脚本的执行具有原子性.
/**
* 该方法主要用来防止超卖,将Compare And Set使用Lua脚本封装,传入Redis执行.
* 因为Redis是单线程执行,所以Lua脚本的执行具有原子性.
* @param productId 产品ID
* @param increment 购买金额
* @return "NOT_ENOUGH":可售金额不足或者加入购买金额后,可售金额不足
* "ENOUGH":加入购买金额后,可售金额足够
* "JUST_SOLD_OUT":加入购买金额后,产品刚好售罄
*/
public StockStatus compareAndSetProductCachedStock(Integer productId, BigDecimal increment) {
String script = "local key, amount = KEYS[1], ARGV[1];\n" +
"local sold_amount = redis.call('hget', key, 'sold_amount') * 100; \n" +
"local raised_amount = redis.call('hget', key, 'raised_amount')*100; \n" +
"local temp_amount = sold_amount + amount*100; \n" +
"if tostring(temp_amount) ~= tostring(raised_amount) and temp_amount > raised_amount then\n" +
" return 'NOT_ENOUGH';\n" +
"elseif tostring(temp_amount) ~= tostring(raised_amount) and temp_amount < raised_amount then\n" +
" redis.call('hincrbyfloat', key, 'sold_amount', amount);\n" +
" return 'ENOUGH';\n" +
"else\n" +
" redis.call('hincrbyfloat', key, 'sold_amount', amount);\n" +
" redis.call('hset', key, 'trade_status_id', 3);\n" +
" return 'JUST_SOLD_OUT';\n" +
"end;";
String key = getCachedProductKey(productId);
List
add(key);
}};
String result = String.valueOf(RedisUtil.execute(script, keys, String.valueOf(increment.setScale(2, BigDecimal.ROUND_HALF_UP))));
return StockStatus.valueOf(result);
}