2 * Copyright 2017 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.
21 #include <folly/Function.h>
25 using Func = Function<void()>;
27 /// An Executor accepts units of work with add(), which should be
31 // Workaround for a linkage problem with explicitly defaulted dtor t22914621
32 virtual ~Executor() {}
34 /// Enqueue a function to executed by this executor. This and all
35 /// variants must be threadsafe.
36 virtual void add(Func) = 0;
38 /// Enqueue a function with a given priority, where 0 is the medium priority
39 /// This is up to the implementation to enforce
40 virtual void addWithPriority(Func, int8_t priority);
42 virtual uint8_t getNumPriorities() const {
46 static const int8_t LO_PRI = SCHAR_MIN;
47 static const int8_t MID_PRI = 0;
48 static const int8_t HI_PRI = SCHAR_MAX;
58 explicit operator bool() const {
59 return executor_ != nullptr;
62 Executor* get() const {
63 return executor_.get();
67 friend class Executor;
68 explicit KeepAlive(folly::Executor* executor) : executor_(executor) {}
71 void operator()(folly::Executor* executor) {
72 executor->keepAliveRelease();
75 std::unique_ptr<folly::Executor, Deleter> executor_;
78 /// Returns a keep-alive token which guarantees that Executor will keep
79 /// processing tasks until the token is released.
81 /// If executor does not support keep-alive functionality - dummy token will
83 virtual KeepAlive getKeepAliveToken() {
88 virtual void keepAliveAcquire();
89 virtual void keepAliveRelease();
91 KeepAlive makeKeepAlive() {
92 return KeepAlive{this};