1138 (#1156)

* add leaky rate limiter algorithm

* Add leaky rate limiter algorithm

soul-plugin/soul-plugin-ratelimiter/src/main/java/org/dromara/soul/plugin/ratelimiter/algorithm/LeakyBucketRateLimiterAlgorithm.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.dromara.soul.plugin.ratelimiter.algorithm;
+
+import org.dromara.soul.spi.Join;
+
+/**
+ * The type Leaky bucket rate limiter algorithm.
+ *
+ * @author liupenghui
+ */
+@Join
+public class LeakyBucketRateLimiterAlgorithm extends AbstractRateLimiterAlgorithm {
+
+    @Override
+    protected String getScriptName() {
+        return "request_leaky_rate_limiter.lua";
+    }
+
+    @Override
+    protected String getKeyName() {
+        return "request_leaky_rate_limiter";
+    }
+}

soul-plugin/soul-plugin-ratelimiter/src/main/resources/META-INF/scripts/request_leaky_rate_limiter.lua

@@ -0,0 +1,78 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--    http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+
+-- author Redick01
+
+-- current key
+local leaky_bucket_key = KEYS[1]
+-- last update key
+local last_bucket_key = KEYS[2]
+-- capacity
+local capacity = tonumber(ARGV[2])
+-- the rate of leak water
+local rate = tonumber(ARGV[1])
+-- request count
+local requested = tonumber(ARGV[4])
+-- current timestamp
+local now = tonumber(ARGV[3])
+-- the key life time
+local key_lifetime = math.ceil((capacity / rate) + 1)
+
+
+-- the yield of water in the bucket default 0
+local key_bucket_count = tonumber(redis.call("GET", leaky_bucket_key)) or 0
+
+-- the last update time default now
+local last_time = tonumber(redis.call("GET", last_bucket_key)) or now
+
+-- the time difference
+local millis_since_last_leak = now - last_time
+
+-- the yield of water had lasted
+local leaks = millis_since_last_leak * rate
+
+if leaks > 0 then
+    -- clean up the bucket
+    if leaks >= key_bucket_count then
+        key_bucket_count = 0
+    else
+        -- compute the yield of water in the bucket
+        key_bucket_count = key_bucket_count - leaks
+    end
+    last_time = now
+end
+
+-- is allowed pass default not allow
+local is_allow = 0
+
+local new_bucket_count = key_bucket_count + requested
+-- allow
+if new_bucket_count <= capacity then
+    is_allow = 1
+else
+    -- not allow
+    return {is_allow, new_bucket_count}
+end
+
+-- update the key bucket water yield
+redis.call("SETEX", leaky_bucket_key, key_lifetime, new_bucket_count)
+
+-- update last update time
+redis.call("SETEX", last_bucket_key, key_lifetime, now)
+
+-- return
+return {is_allow, new_bucket_count}

soul-plugin/soul-plugin-ratelimiter/src/main/resources/META-INF/soul/org.dromara.soul.plugin.ratelimiter.algorithm.RateLimiterAlgorithm

@@ -16,4 +16,5 @@
 
 concurrent=org.dromara.soul.plugin.ratelimiter.algorithm.ConcurrentRateLimiterAlgorithm
 tokenBucket=org.dromara.soul.plugin.ratelimiter.algorithm.TokenBucketRateLimiterAlgorithm
-slidingWindow=org.dromara.soul.plugin.ratelimiter.algorithm.SlidingWindowRateLimiterAlgorithm
+leakyBucket=org.dromara.soul.plugin.ratelimiter.algorithm.LeakyBucketRateLimiterAlgorithm
+slidingWindow=org.dromara.soul.plugin.ratelimiter.algorithm.SlidingWindowRateLimiterAlgorithm