| /* |
| * 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 tps |
| |
| import ( |
| "sync/atomic" |
| "time" |
| ) |
| |
| import ( |
| "github.com/apache/dubbo-go/common/constant" |
| "github.com/apache/dubbo-go/common/extension" |
| "github.com/apache/dubbo-go/filter" |
| ) |
| |
| const ( |
| // FixedWindowKey defines tps limit algorithm |
| FixedWindowKey = "fixedWindow" |
| ) |
| |
| func init() { |
| creator := &fixedWindowStrategyCreator{} |
| extension.SetTpsLimitStrategy(FixedWindowKey, creator) |
| extension.SetTpsLimitStrategy(constant.DEFAULT_KEY, creator) |
| } |
| |
| // FixedWindowTpsLimitStrategyImpl implements the TPS limit strategy base on requests count during the interval |
| /** |
| * It's the same as default implementation in Java |
| * It's not a thread-safe implementation. |
| * It you want to use the thread-safe implementation, please use ThreadSafeFixedWindowTpsLimitStrategyImpl |
| * This is the default implementation. |
| * |
| * "UserProvider": |
| * registry: "hangzhouzk" |
| * protocol : "dubbo" |
| * interface : "com.ikurento.user.UserProvider" |
| * ... # other configuration |
| * tps.limiter: "method-service" # the name of limiter |
| * tps.limit.strategy: "default" or "fixedWindow" # service-level |
| * methods: |
| * - name: "GetUser" |
| * tps.interval: 3000 |
| * tps.limit.strategy: "default" or "fixedWindow" # method-level |
| */ |
| type FixedWindowTpsLimitStrategyImpl struct { |
| rate int32 |
| interval int64 |
| count int32 |
| timestamp int64 |
| } |
| |
| // IsAllowable determines if the requests over the TPS limit within the interval. |
| // It is not thread-safe. |
| func (impl *FixedWindowTpsLimitStrategyImpl) IsAllowable() bool { |
| |
| current := time.Now().UnixNano() |
| if impl.timestamp+impl.interval < current { |
| // it's a new window |
| // if a lot of threads come here, the count will be set to 0 several times. |
| // so the return statement will be wrong. |
| impl.timestamp = current |
| impl.count = 0 |
| } |
| // this operation is thread-safe, but count + 1 may be overflow |
| return atomic.AddInt32(&impl.count, 1) <= impl.rate |
| } |
| |
| type fixedWindowStrategyCreator struct{} |
| |
| // Create returns a FixedWindowTpsLimitStrategyImpl instance with pre-configured limit rate and interval |
| func (creator *fixedWindowStrategyCreator) Create(rate int, interval int) filter.TpsLimitStrategy { |
| return &FixedWindowTpsLimitStrategyImpl{ |
| rate: int32(rate), |
| interval: int64(interval) * int64(time.Millisecond), // convert to ns |
| count: 0, |
| timestamp: time.Now().UnixNano(), |
| } |
| } |