1//
2// detail/task_io_service.hpp
3// ~~~~~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
12#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19
20#if !defined(BOOST_ASIO_HAS_IOCP)
21
22#include <boost/system/error_code.hpp>
23#include <boost/asio/io_service.hpp>
24#include <boost/asio/detail/atomic_count.hpp>
25#include <boost/asio/detail/call_stack.hpp>
26#include <boost/asio/detail/event.hpp>
27#include <boost/asio/detail/mutex.hpp>
28#include <boost/asio/detail/op_queue.hpp>
29#include <boost/asio/detail/reactor_fwd.hpp>
30#include <boost/asio/detail/task_io_service_operation.hpp>
31
32#include <boost/asio/detail/push_options.hpp>
33
34namespace boost {
35namespace asio {
36namespace detail {
37
38struct task_io_service_thread_info;
39
40class task_io_service
41 : public boost::asio::detail::service_base<task_io_service>
42{
43public:
44 typedef task_io_service_operation operation;
45
46 // Constructor. Specifies the number of concurrent threads that are likely to
47 // run the io_service. If set to 1 certain optimisation are performed.
48 BOOST_ASIO_DECL task_io_service(boost::asio::io_service& io_service,
49 std::size_t concurrency_hint = 0);
50
51 // Destroy all user-defined handler objects owned by the service.
52 BOOST_ASIO_DECL void shutdown_service();
53
54 // Initialise the task, if required.
55 BOOST_ASIO_DECL void init_task();
56
57 // Run the event loop until interrupted or no more work.
58 BOOST_ASIO_DECL std::size_t run(boost::system::error_code& ec);
59
60 // Run until interrupted or one operation is performed.
61 BOOST_ASIO_DECL std::size_t run_one(boost::system::error_code& ec);
62
63 // Poll for operations without blocking.
64 BOOST_ASIO_DECL std::size_t poll(boost::system::error_code& ec);
65
66 // Poll for one operation without blocking.
67 BOOST_ASIO_DECL std::size_t poll_one(boost::system::error_code& ec);
68
69 // Interrupt the event processing loop.
70 BOOST_ASIO_DECL void stop();
71
72 // Determine whether the io_service is stopped.
73 BOOST_ASIO_DECL bool stopped() const;
74
75 // Reset in preparation for a subsequent run invocation.
76 BOOST_ASIO_DECL void reset();
77
78 // Notify that some work has started.
79 void work_started()
80 {
81 ++outstanding_work_;
82 }
83
84 // Notify that some work has finished.
85 void work_finished()
86 {
87 if (--outstanding_work_ == 0)
88 stop();
89 }
90
91 // Return whether a handler can be dispatched immediately.
92 bool can_dispatch()
93 {
94 return thread_call_stack::contains(this) != 0;
95 }
96
97 // Request invocation of the given handler.
98 template <typename Handler>
99 void dispatch(Handler& handler);
100
101 // Request invocation of the given handler and return immediately.
102 template <typename Handler>
103 void post(Handler& handler);
104
105 // Request invocation of the given operation and return immediately. Assumes
106 // that work_started() has not yet been called for the operation.
107 BOOST_ASIO_DECL void post_immediate_completion(
108 operation* op, bool is_continuation);
109
110 // Request invocation of the given operation and return immediately. Assumes
111 // that work_started() was previously called for the operation.
112 BOOST_ASIO_DECL void post_deferred_completion(operation* op);
113
114 // Request invocation of the given operations and return immediately. Assumes
115 // that work_started() was previously called for each operation.
116 BOOST_ASIO_DECL void post_deferred_completions(op_queue<operation>& ops);
117
118 // Process unfinished operations as part of a shutdown_service operation.
119 // Assumes that work_started() was previously called for the operations.
120 BOOST_ASIO_DECL void abandon_operations(op_queue<operation>& ops);
121
122private:
123 // Structure containing thread-specific data.
124 typedef task_io_service_thread_info thread_info;
125
126 // Enqueue the given operation following a failed attempt to dispatch the
127 // operation for immediate invocation.
128 BOOST_ASIO_DECL void do_dispatch(operation* op);
129
130 // Run at most one operation. May block.
131 BOOST_ASIO_DECL std::size_t do_run_one(mutex::scoped_lock& lock,
132 thread_info& this_thread, const boost::system::error_code& ec);
133
134 // Poll for at most one operation.
135 BOOST_ASIO_DECL std::size_t do_poll_one(mutex::scoped_lock& lock,
136 thread_info& this_thread, const boost::system::error_code& ec);
137
138 // Stop the task and all idle threads.
139 BOOST_ASIO_DECL void stop_all_threads(mutex::scoped_lock& lock);
140
141 // Wake a single idle thread, or the task, and always unlock the mutex.
142 BOOST_ASIO_DECL void wake_one_thread_and_unlock(
143 mutex::scoped_lock& lock);
144
145 // Helper class to perform task-related operations on block exit.
146 struct task_cleanup;
147 friend struct task_cleanup;
148
149 // Helper class to call work-related operations on block exit.
150 struct work_cleanup;
151 friend struct work_cleanup;
152
153 // Whether to optimise for single-threaded use cases.
154 const bool one_thread_;
155
156 // Mutex to protect access to internal data.
157 mutable mutex mutex_;
158
159 // Event to wake up blocked threads.
160 event wakeup_event_;
161
162 // The task to be run by this service.
163 reactor* task_;
164
165 // Operation object to represent the position of the task in the queue.
166 struct task_operation : operation
167 {
168 task_operation() : operation(0) {}
169 } task_operation_;
170
171 // Whether the task has been interrupted.
172 bool task_interrupted_;
173
174 // The count of unfinished work.
175 atomic_count outstanding_work_;
176
177 // The queue of handlers that are ready to be delivered.
178 op_queue<operation> op_queue_;
179
180 // Flag to indicate that the dispatcher has been stopped.
181 bool stopped_;
182
183 // Flag to indicate that the dispatcher has been shut down.
184 bool shutdown_;
185
186 // Per-thread call stack to track the state of each thread in the io_service.
187 typedef call_stack<task_io_service, thread_info> thread_call_stack;
188};
189
190} // namespace detail
191} // namespace asio
192} // namespace boost
193
194#include <boost/asio/detail/pop_options.hpp>
195
196#include <boost/asio/detail/impl/task_io_service.hpp>
197#if defined(BOOST_ASIO_HEADER_ONLY)
198# include <boost/asio/detail/impl/task_io_service.ipp>
199#endif // defined(BOOST_ASIO_HEADER_ONLY)
200
201#endif // !defined(BOOST_ASIO_HAS_IOCP)
202
203#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
204