Seastar
High performance C++ framework for concurrent servers
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exchanger.hh
1/*
2 * This file is open source software, licensed to you under the terms
3 * of the Apache License, Version 2.0 (the "License"). See the NOTICE file
4 * distributed with this work for additional information regarding copyright
5 * ownership. You may not use this file except in compliance with the License.
6 *
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing,
12 * software distributed under the License is distributed on an
13 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14 * KIND, either express or implied. See the License for the
15 * specific language governing permissions and limitations
16 * under the License.
17 */
18/*
19 * Copyright (C) 2015 Cloudius Systems, Ltd.
20 */
21
22#pragma once
23
24#include <mutex>
25#include <condition_variable>
26#include <optional>
27
28namespace seastar {
29
30namespace testing {
31
33protected:
36 std::mutex _mutex;
37 std::condition_variable _cv;
38 std::exception_ptr _exception;
39 void interrupt_ptr(std::exception_ptr e) {
40 std::unique_lock<std::mutex> lock(_mutex);
41 if (!_exception) {
42 _exception = e;
43 _cv.notify_all();
44 }
45 // FIXME: log if already interrupted
46 }
47};
48
49// Single-element blocking queue
50template <typename T>
51class exchanger : public exchanger_base {
52private:
53 std::optional<T> _element;
54
55public:
56 template <typename Exception>
57 void interrupt(Exception e) {
58 try {
59 throw e;
60 } catch (...) {
61 interrupt_ptr(std::current_exception());
62 }
63 }
64 void give(T value) {
65 std::unique_lock<std::mutex> lock(_mutex);
66 _cv.wait(lock, [this] { return !_element || _exception; });
67 if (_exception) {
68 std::rethrow_exception(_exception);
69 }
70 _element = value;
71 _cv.notify_one();
72 }
73 T take() {
74 std::unique_lock<std::mutex> lock(_mutex);
75 _cv.wait(lock, [this] { return bool(_element) || _exception; });
76 if (_exception) {
77 std::rethrow_exception(_exception);
78 }
79 auto v = *_element;
80 _element = {};
81 _cv.notify_one();
82 return v;
83 }
84};
85
86}
87
88}
Definition: exchanger.hh:32
Definition: exchanger.hh:51
Seastar API namespace.
Definition: abort_on_ebadf.hh:26