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00001 // 00002 // pipe_select_interrupter.hpp 00003 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 00004 // 00005 // Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com) 00006 // 00007 // Distributed under the Boost Software License, Version 1.0. (See accompanying 00008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 00009 // 00010 00011 #ifndef ASIO_DETAIL_PIPE_SELECT_INTERRUPTER_HPP 00012 #define ASIO_DETAIL_PIPE_SELECT_INTERRUPTER_HPP 00013 00014 #if defined(_MSC_VER) && (_MSC_VER >= 1200) 00015 # pragma once 00016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) 00017 00018 #include "asio/detail/push_options.hpp" 00019 00020 #include "asio/detail/push_options.hpp" 00021 #include <boost/config.hpp> 00022 #include <boost/throw_exception.hpp> 00023 #include "asio/detail/pop_options.hpp" 00024 00025 #if !defined(BOOST_WINDOWS) && !defined(__CYGWIN__) 00026 00027 #include "asio/detail/push_options.hpp" 00028 #include <fcntl.h> 00029 #include "asio/detail/pop_options.hpp" 00030 00031 #include "asio/error.hpp" 00032 #include "asio/system_error.hpp" 00033 #include "asio/detail/socket_types.hpp" 00034 00035 namespace asio { 00036 namespace detail { 00037 00038 class pipe_select_interrupter 00039 { 00040 public: 00041 // Constructor. 00042 pipe_select_interrupter() 00043 { 00044 int pipe_fds[2]; 00045 if (pipe(pipe_fds) == 0) 00046 { 00047 read_descriptor_ = pipe_fds[0]; 00048 ::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK); 00049 write_descriptor_ = pipe_fds[1]; 00050 ::fcntl(write_descriptor_, F_SETFL, O_NONBLOCK); 00051 } 00052 else 00053 { 00054 asio::error_code ec(errno, 00055 asio::error::get_system_category()); 00056 asio::system_error e(ec, "pipe_select_interrupter"); 00057 boost::throw_exception(e); 00058 } 00059 } 00060 00061 // Destructor. 00062 ~pipe_select_interrupter() 00063 { 00064 if (read_descriptor_ != -1) 00065 ::close(read_descriptor_); 00066 if (write_descriptor_ != -1) 00067 ::close(write_descriptor_); 00068 } 00069 00070 // Interrupt the select call. 00071 void interrupt() 00072 { 00073 char byte = 0; 00074 if (::write(write_descriptor_, &byte, 1) == -1) { 00075 // do nothing 00076 } 00077 } 00078 00079 // Reset the select interrupt. Returns true if the call was interrupted. 00080 bool reset() 00081 { 00082 char data[1024]; 00083 int bytes_read = ::read(read_descriptor_, data, sizeof(data)); 00084 bool was_interrupted = (bytes_read > 0); 00085 while (bytes_read == sizeof(data)) 00086 bytes_read = ::read(read_descriptor_, data, sizeof(data)); 00087 return was_interrupted; 00088 } 00089 00090 // Get the read descriptor to be passed to select. 00091 int read_descriptor() const 00092 { 00093 return read_descriptor_; 00094 } 00095 00096 private: 00097 // The read end of a connection used to interrupt the select call. This file 00098 // descriptor is passed to select such that when it is time to stop, a single 00099 // byte will be written on the other end of the connection and this 00100 // descriptor will become readable. 00101 int read_descriptor_; 00102 00103 // The write end of a connection used to interrupt the select call. A single 00104 // byte may be written to this to wake up the select which is waiting for the 00105 // other end to become readable. 00106 int write_descriptor_; 00107 }; 00108 00109 } // namespace detail 00110 } // namespace asio 00111 00112 #endif // !defined(BOOST_WINDOWS) && !defined(__CYGWIN__) 00113 00114 #include "asio/detail/pop_options.hpp" 00115 00116 #endif // ASIO_DETAIL_PIPE_SELECT_INTERRUPTER_HPP