programming language translator

. There are several solutions for the above problem:Use global buffersCreates a buffer and then releases it at the end of the operationUse a Collection object to manage these sockets and other data, such as buffer arraysThe first method is obviously not very good, because we all know that using global variables is bad. Also, what if two instances use the same buffer?Here's the second way implementation: void on_read (char * ptr, const Boost::system::error_code err, std::size_t read_

; username_ >> username_; Write ("Login ok\n"); Update_clients_changed ();}void On_ping () { Write (clients_changed_? "Ping client_list_changed\n": "Ping Ok\n "); Clients_changed_ = false; } void On_clients () { std::string msg; {Boost::recursive_mutex::scoped_lock lk (CS); for (Array::const_iterator B = Clients.begin (), E = clients. End (); b! = e; ++B) msg + = (*b)->username () + "";} Write ("clients" + msg +

); Basically here, we are acknowledge //That we are clients received our notifications}void do_write (const std::string msg) { Std::copy (Msg.begin (), Msg.end (), write_buffer_); Sock_.async_write_some (Buffer (Write_buffer_, msg.size ()), MEM_FN2 (on_write,_1,_2));}void on_write (const Error_code err, size_t bytes) {Do_read (); }as long as an event occurs, we assume that it is on_new_client_event, and all clients that need to be notified are sent a mess

(written to a new buffer) is required, in addition to the asynchronous write back to the other part .for each successful write operation, destroy (or reuse) this bufferI'll leave this as a contact for you. SummaryThere are a number of things to consider when choosing to synchronize or async. The first thing to consider is to avoid confusing them. in this chapter, we have learned that: How easy it is to implement, test, and debug each type of application How threads affect your app

Blocking_udp_client.cpp. Poll_one Methoduse a non-blocking approachmostrun a ready-to-run wait operation:If there is at least one waiting operation and is ready to run in a non-blocking manner, the Poll_one method runs it and returns 1Otherwise, the method returns 0 immediatelyoperation waiting, ready to run in a non-blocking manner, usually means the following:a timer expires, and then its async_wait processing method needs to be calledan I/O operation is completed (such as Async_read), and th

contains the main logic of the class:void On_connect (const Error_code err) { if (!err) do_write (Message_ + "\ n"); else stop (); } void On_read (const Error_code err, size_t bytes) { if (!err) { std::string copy (Read_buffer_, bytes-1); Std::cout Std::endl; }Stop (); } void On_write (const Error_code err, size_t bytes) { do_read ();}when we are connected, we send a message to the server, Do_write (). When the write operation

Read = FALSE;void Deadline_handler (const Boost::system::error_code ) {Std::cout Std::endl;}void Read_handler (const Boost::system::error_code ) {Read = true;}Ip::tcp::socket sock (service);...Read = false;Char data[512];Sock.async_read_some (Buffer (data, 512));Deadline_timer T (service, Boost::p osix_time::milliseconds (100));T.async_wait (deadline_handler);Service.run ();In the previous code snippet, if you read the data before the deadline, read is set to True so our partner notifies us in

a client, and then you will have two threads calling On_read for a client at the same time, and the result is a data conflict that may even cause the software to crash. you will find that the code becomes extremely complex. A third option for synchronous programming is to open a thread for each connection. When concurrent threads increased, this turned out to be the least likely scenario. Then, let's look at asynchronous

::fork_parent);... }It is recommended to use the service that will be called on different threads, although Boost.asio allows it, I strongly recommend that you use multi-threading, because using Boost::thread is a piece of cake. Summaryfight to make your code simple and clear. Learn and use the process. This will allow you to minimize the debugging effort, but only if there are potential bugs in the code, Boost.asio will lend a helping hand, as we have seen in the debugging chapters. If you need

out, we close its connection:void On_check_ping () { ptime now = Microsec_clock::local_time (); if ((now-last_ping). Total_milliseconds () > 5000) Stop (); last_ping = boost::p osix_time::microsec_clock::local_time (); } void Post_check_ping () { Timer_.expires_from_now (boost::p osix_time::millisec (5000)); Timer_.async_wait (MEM_FN (on_check_ping)); }This is the implementation of the entire service side. You can run and let it work! In the code, I

, which creates a handle of 1 (in this case, all the handles are talk_to_svr::step) Handle 1 is called (when successfully connecting to the server) Handle 1 calls Async_send, which creates a handle 2 (here, we send login information to the server) Handle 1 exit Handle 2 is called and 11 bytes are sent out (login John) Handle 2 calls Async_receive, which creates a handle of 3 (we wait for the server to return the result of the login) Handle 2 exit Handle 3 is called and we receive

Similarly, in another section, when reading a message, you need to parse it, that is, when you read the data to a fragment, if the data is not a string, you need to convert it to a string. This is done by default when you use the >> operator to read something. The last thing to give is a very famous, cool trick to use the following code snippet to output the contents of the Streambuf to the console Streambuf buf; ... Std::cout Similarly, use the following code snipp

() { //For the result of our login operation write ("login" + username_ + "\ n"); Read_answer (); while (Started_) { Write_request (); Read_answer (); ...} }we modify it to accommodate the second case:void Loop () {while (started_) { Read_notification (); Write_answer (); } } void Read_notification () { Already_read_ = 0; Read (sock_, buffer (buff_), Boost::bind (talk_to_svr::read

for socket input processing intreuse_address If True, Sockets can be bound to a used address boolsend_buffer_size Socket send buffer size / intsend_low_watermark N Bsp Specify the minimum number of bytes sent by the socket data Intip::v6_only If true, only IPv6 connections are allowed BOOL Each name represents an internal socket typedef or class. The following is the use of them: Ip::tcp::endpoint EP (Ip::address::from_string ("127.0.0.1"), 80);Ip:

delimiter, but a complete processing method. The format of the finished processing method is:pairRead_until (Stream, Stream_buffer, Delim): This method runs a synchronous read operation with the same meaning as async_read_until.Read_until (Stream, Stream_buffer,completion): This method runs a synchronous read operation with the same meaning as async_read_until.The following example reads until a specified punctuation mark is readTypedefbuffers_iteratorstd::p airwhile (begin = end)if (std::ispun

delimiter, but a complete processing method. The processing method is completed in the format:pairRead_until (Stream, Stream_buffer, Delim): This method performs a synchronous read operation with the same meaning as the async_read_until.Read_until (Stream, Stream_buffer,completion): This method performs a synchronous read operation with the same meaning as the async_read_until.The following example reads until a specified punctuation mark is readTypedefbuffers_iteratorstd::p airwhile (begin = e

::error_code compute_file_checksum (std::string file_name) {HANDLE file =:: CreateFile (File_name.c_str (), generic_read, 0, 0, Open_always, File_attribute_normal | file_flag_overlapped, 0); Windows::random_access_handle h (service, file); Long buff[1024]; checksum = 0; size_t bytes = 0, at = 0; Boost::system::error_code EC; while (bytes = Read_at (h, in, buffer (buff), EC)) > 0) {at + = bytes; bytes/= sizeof (long); for (size_t

)); Process_msg (); } void Process_msg () { std::string msg (buff_, already_read_); if (Msg.find ("login") = = 0) on_login (); else if (Msg.find ("ping") = = 0) on_ping (msg); else if (Msg.find ("clients") = = 0) on_clients (msg); else std::cerr }for reading results, we use the read_complete mentioned in the previous section to ensure that we can all go to the newline character (' \ n '). Logic is in process_msg (), where we read the return of the server a

somewhat similar to the previous Answer_to_client method, which shows us how the second method is implemented: struct talk_to_client:boost::enable_shared_from_this ... void Answer_to_client () { try { read_request (); Process_request (); } catch (boost::system::system_error) {Stop (); }} }; We need to modify it to make it look like the following code snippet: struct talk_to_client:boost::enable_shared_from_this

("Login ok\n"); Update_clients_changed ();}void On_ping () { Write (clients_changed_? "Ping client_list_changed\n": "Ping Ok\n "); Clients_changed_ = false; } void On_clients () { std::string msg; {Boost::recursive_mutex::scoped_lock lk (CS); for (Array::const_iterator B = Clients.begin (), E = clients. End (); b! = e; ++B) msg + = (*b)->username () + "";} Write ("clients" + msg + "\ n"); } void Write (const std: