2 * Copyright 2016 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
24 #include <folly/Function.h>
28 using Func = Function<void()>;
30 /// An Executor accepts units of work with add(), which should be
34 virtual ~Executor() = default;
36 /// Enqueue a function to executed by this executor. This and all
37 /// variants must be threadsafe.
38 virtual void add(Func) = 0;
40 /// Enqueue a function with a given priority, where 0 is the medium priority
41 /// This is up to the implementation to enforce
42 virtual void addWithPriority(Func, int8_t /*priority*/) {
43 throw std::runtime_error(
44 "addWithPriority() is not implemented for this Executor");
47 virtual uint8_t getNumPriorities() const {
51 static const int8_t LO_PRI = SCHAR_MIN;
52 static const int8_t MID_PRI = 0;
53 static const int8_t HI_PRI = SCHAR_MAX;
55 /// A convenience function for shared_ptr to legacy functors.
57 /// Sometimes you have a functor that is move-only, and therefore can't be
58 /// converted to a std::function (e.g. std::packaged_task). In that case,
59 /// wrap it in a shared_ptr (or maybe folly::MoveWrapper) and use this.
62 this->add([fn]() mutable { (*fn)(); });