1 // Copyright 2023 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 #pragma once 15 16 #include "pw_function/function.h" 17 #include "pw_status/status.h" 18 19 namespace pw::async { 20 21 class Dispatcher; 22 class Task; 23 24 struct Context { 25 Dispatcher* dispatcher; 26 Task* task; 27 }; 28 29 // A TaskFunction is a unit of work that is wrapped by a Task and executed on a 30 // Dispatcher. 31 // 32 // TaskFunctions take a `Context` as their first argument. Before executing a 33 // Task, the Dispatcher sets the pointer to itself and to the Task in `Context`. 34 // 35 // TaskFunctions take a `Status` as their second argument. When a Task is 36 // running as normal, |status| == PW_STATUS_OK. If a Task will not be able to 37 // run as scheduled, the Dispatcher will still invoke the TaskFunction with 38 // |status| == PW_STATUS_CANCELLED. This provides an opportunity to reclaim 39 // resources held by the Task. 40 // 41 // A Task will not run as scheduled if, for example, it is still waiting when 42 // the Dispatcher shuts down. 43 using TaskFunction = Function<void(Context&, Status)>; 44 45 } // namespace pw::async 46