1 /* 2 * Copyright (c) Facebook, Inc. and its affiliates. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <chrono> 20 21 #include <folly/experimental/observer/Observer.h> 22 23 namespace folly { 24 namespace observer { 25 26 /** 27 * The returned Observer will proxy updates from the input observer but will 28 * delay the propagation of each update by some duration between 0 ms and 29 * lag + jitter. In addition, if an update arrives while no preceding jittered 30 * updates are still in flight, then the delay applied to the latest update will 31 * be a uniformly random duration between lag - jitter and lag + jitter. 32 */ 33 template <typename T> 34 Observer<T> withJitter( 35 Observer<T> observer, 36 std::chrono::milliseconds lag, 37 std::chrono::milliseconds jitter); 38 39 } // namespace observer 40 } // namespace folly 41 42 #include <folly/experimental/observer/WithJitter-inl.h> 43