117 lines
4.5 KiB
Java
117 lines
4.5 KiB
Java
/*
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* The MIT License (MIT)
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*
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* Copyright © 2020 xrv <xrg@live.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package io.github.ehlxr.redis;
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/**
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* redis lock/滑动时间窗口限流
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*
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* @author ehlxr
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* @since 2021-07-15 22:42.
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*/
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public interface RedisDAO {
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/**
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* 释放分布式锁时使用的 lua 脚本，保证原子性
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* <p>
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* if (redis.call('get', KEYS[1]) == ARGV[1])
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* then
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* return redis.call('del', KEYS[1])
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* else
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* return 0
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* end
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*/
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String RELEASE_LOCK_LUA = "if (redis.call('get', KEYS[1]) == ARGV[1]) then return redis.call('del', KEYS[1]) else return 0 end";
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/**
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* 滑动窗口限流使用的 lua 脚本，保证原子性
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* <p>
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* local key = KEYS[1];
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* local index = tonumber(ARGV[1]);
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* local time_window = tonumber(ARGV[2]);
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* local now_time = tonumber(ARGV[3]);
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* local far_time = redis.call('lindex', key, index);
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* if (not far_time)
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* then
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* redis.call('lpush', key, now_time);
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* redis.call('pexpire', key, time_window+1000);
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* return 1;
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* end
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* if (now_time - far_time > time_window)
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* then
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* redis.call('rpop', key);
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* redis.call('lpush', key, now_time);
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* redis.call('pexpire', key, time_window+1000);
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* return 1;
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* else
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* return 0;
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* end
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*/
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String SLIDE_WINDOW_LUA = "local key = KEYS[1];\n" + "local index = tonumber(ARGV[1]);\n" + "local time_window = tonumber(ARGV[2]);\n" + "local now_time = tonumber(ARGV[3]);\n" + "local far_time = redis.call('lindex', key, index);\n" + "if (not far_time)\n" + "then\n" + " redis.call('lpush', key, now_time);\n" + " redis.call('pexpire', key, time_window+1000);\n" + " return 1;\n" + "end\n" + "\n" + "if (now_time - far_time > time_window)\n" + "then\n" + " redis.call('rpop', key);\n" + " redis.call('lpush', key, now_time);\n" + " redis.call('pexpire', key, time_window+1000);\n" + " return 1;\n" + "else\n" + " return 0;\n" + "end";
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/**
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* 获取分布式锁
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*
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* @param key key
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* @param value value，需要保证全局唯一，用来删除分布式锁时判断身份使用
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* @param expireTime 锁过期时间，毫秒，防止业务崩溃未删除锁，导致死锁
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* @return 是否获取成功锁
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*/
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Boolean getDistributedLock(String key, String value, long expireTime);
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/**
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* 释放分布式锁
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*
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* @param key key
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* @param value value，需要和获取锁时传入的一致
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* @return 是否释放成功锁
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*/
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Boolean releaseDistributedLock(String key, String value);
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/**
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* 分布式限流队列，在时间窗口内（包含该时间点），判断是否达到限流的阀值
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* 本接口实现的方法通过加锁避免并发问题，性能不高。只是为了说明限流逻辑如何实现
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*
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* @param key key
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* @param count 限流阀值
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* @param timeWindow 限流时间窗口
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* @return 是否允许通过（通过即不进行限流）
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*/
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Boolean slideWindow(String key, int count, long timeWindow);
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/**
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* 分布式限流队列，在时间窗口内（包含该时间点），判断是否达到限流的阀值
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* 本接口实现的方法通过 Lua 脚本避免并发问题，性能较高。
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*
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* @param key key
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* @param count 限流阀值
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* @param timeWindow 限流时间窗口
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* @return 是否允许通过（通过即不进行限流）
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*/
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Boolean slideWindowLua(String key, int count, long timeWindow);
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}
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