Line data Source code
1 : // Copyright (c) 2012-2021 Made to Order Software Corp. All Rights Reserved
2 : //
3 : // https://snapwebsites.org/project/eventdispatcher
4 : // contact@m2osw.com
5 : //
6 : // This program is free software; you can redistribute it and/or modify
7 : // it under the terms of the GNU General Public License as published by
8 : // the Free Software Foundation; either version 2 of the License, or
9 : // (at your option) any later version.
10 : //
11 : // This program is distributed in the hope that it will be useful,
12 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : // GNU General Public License for more details.
15 : //
16 : // You should have received a copy of the GNU General Public License along
17 : // with this program; if not, write to the Free Software Foundation, Inc.,
18 : // 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 :
20 : /** \file
21 : * \brief Implementation client permanent message connection.
22 : *
23 : * This class implements a permanent connection to a Unix socket. This
24 : * means if the server is restarted, this class is capable to automatically
25 : * reconnect under the hood. This can be done using a thread so if the
26 : * connect() command is slow (needs to time out), it won't block the
27 : * rest of your event loop.
28 : */
29 :
30 :
31 : // self
32 : //
33 : #include "eventdispatcher/local_stream_client_permanent_message_connection.h"
34 :
35 : #include "eventdispatcher/communicator.h"
36 : #include "eventdispatcher/exception.h"
37 : //#include "eventdispatcher/local_stream_server_client_message_connection.h"
38 : #include "eventdispatcher/local_stream_client_message_connection.h"
39 : #include "eventdispatcher/thread_done_signal.h"
40 :
41 :
42 : // snaplogger lib
43 : //
44 : #include <snaplogger/message.h>
45 :
46 :
47 : // snapdev lib
48 : //
49 : //#include <snapdev/not_used.h>
50 :
51 :
52 : // cppthread lib
53 : //
54 : #include <cppthread/exception.h>
55 : #include <cppthread/guard.h>
56 : #include <cppthread/runner.h>
57 : #include <cppthread/thread.h>
58 :
59 :
60 : // C++ lib
61 : //
62 : //#include <cstring>
63 :
64 :
65 : // C lib
66 : //
67 : //#include <sys/socket.h>
68 :
69 :
70 : // last include
71 : //
72 : #include <snapdev/poison.h>
73 :
74 :
75 :
76 : namespace ed
77 : {
78 :
79 :
80 :
81 : namespace detail
82 : {
83 :
84 :
85 : /** \brief Internal implementation of the local_stream_client_permanent_message_connection class.
86 : *
87 : * This class is used to handle a thread that will process a connection for
88 : * us. This allows us to connect in any amount of time required by the
89 : * Unix system to obtain the connection with the remote server.
90 : *
91 : * \todo
92 : * Having threads at the time we do a fork() is not safe. We may
93 : * want to reconsider offering this functionality here. Because at
94 : * this time we would have no control of when the thread is created
95 : * and thus a way to make sure that no such thread is running when
96 : * we call fork().
97 : */
98 : class local_stream_client_permanent_message_connection_impl
99 : {
100 : public:
101 1 : class messenger
102 : : public local_stream_client_message_connection
103 : {
104 : public:
105 : typedef std::shared_ptr<messenger> pointer_t;
106 :
107 1 : messenger(
108 : local_stream_client_permanent_message_connection * parent
109 : , addr::unix const & address
110 : , bool const blocking
111 : , bool const close_on_exec)
112 1 : : local_stream_client_message_connection(
113 : address
114 : , blocking
115 : , close_on_exec)
116 1 : , f_parent(parent)
117 : {
118 1 : set_name("local_stream_client_permanent_message_connection_impl::messenger");
119 1 : }
120 :
121 : messenger(messenger const & rhs) = delete;
122 : messenger & operator = (messenger const & rhs) = delete;
123 :
124 : // connection implementation
125 2 : virtual void process_empty_buffer()
126 : {
127 2 : local_stream_client_message_connection::process_empty_buffer();
128 2 : f_parent->process_empty_buffer();
129 2 : }
130 :
131 : // connection implementation
132 0 : virtual void process_error()
133 : {
134 0 : local_stream_client_message_connection::process_error();
135 0 : f_parent->process_error();
136 0 : }
137 :
138 : // connection implementation
139 0 : virtual void process_hup()
140 : {
141 0 : local_stream_client_message_connection::process_hup();
142 0 : f_parent->process_hup();
143 0 : }
144 :
145 : // connection implementation
146 0 : virtual void process_invalid()
147 : {
148 0 : local_stream_client_message_connection::process_invalid();
149 0 : f_parent->process_invalid();
150 0 : }
151 :
152 : // local_stream_server_client_message_connection implementation
153 1 : virtual void process_message(message const & msg)
154 : {
155 : // We call the dispatcher from our parent since the child
156 : // (this messenger) is not given a dispatcher
157 : //
158 2 : message copy(msg);
159 1 : f_parent->dispatch_message(copy);
160 1 : }
161 :
162 : private:
163 : local_stream_client_permanent_message_connection * f_parent = nullptr;
164 : };
165 :
166 1 : class thread_signal_handler
167 : : public thread_done_signal
168 : {
169 : public:
170 : typedef std::shared_ptr<thread_signal_handler> pointer_t;
171 :
172 1 : thread_signal_handler(local_stream_client_permanent_message_connection_impl * parent_impl)
173 1 : : f_parent_impl(parent_impl)
174 : {
175 1 : set_name("local_stream_client_permanent_message_connection_impl::thread_signal_handler");
176 1 : }
177 :
178 : thread_signal_handler(thread_signal_handler const & rhs) = delete;
179 : thread_signal_handler & operator = (thread_signal_handler const & rhs) = delete;
180 :
181 : /** \brief This signal was emitted.
182 : *
183 : * This function gets called whenever the thread is just about to
184 : * quit. Calling f_thread.is_running() may still return true when
185 : * you get in the 'thread_done()' callback. However, an
186 : * f_thread.stop() will return very quickly.
187 : */
188 1 : virtual void process_read()
189 : {
190 1 : thread_done_signal::process_read();
191 :
192 1 : f_parent_impl->thread_done();
193 1 : }
194 :
195 : private:
196 : local_stream_client_permanent_message_connection_impl * f_parent_impl = nullptr;
197 : };
198 :
199 1 : class runner
200 : : public cppthread::runner
201 : {
202 : public:
203 1 : runner(
204 : local_stream_client_permanent_message_connection_impl * parent_impl
205 : , addr::unix const & address
206 : , bool const blocking = false
207 : , bool const close_on_exec = true)
208 1 : : cppthread::runner("background local_stream_client_permanent_message_connection for asynchronous connections")
209 : , f_parent_impl(parent_impl)
210 : , f_address(address)
211 : , f_blocking(blocking)
212 1 : , f_close_on_exec(close_on_exec)
213 : {
214 1 : }
215 :
216 : runner(runner const & rhs) = delete;
217 : runner & operator = (runner const & rhs) = delete;
218 :
219 :
220 : /** \brief This is the actual function run by the thread.
221 : *
222 : * This function calls the connect() function and then
223 : * tells the main thread we are done.
224 : */
225 1 : virtual void run()
226 : {
227 1 : connect();
228 :
229 : // tell the main thread that we are done
230 : //
231 1 : f_parent_impl->trigger_thread_done();
232 1 : }
233 :
234 :
235 : /** \brief This function attempts to connect.
236 : *
237 : * This function attempts a connection to the specified address
238 : * and port with the specified mode (i.e. plain or encrypted.)
239 : *
240 : * The function may take a long time to succeed connecting with
241 : * the server. The main thread will be awaken whenever this
242 : * thread dies.
243 : *
244 : * If an error occurs, then the f_socket variable member will
245 : * be set to -1. Otherwise it represents the socket that we
246 : * just connected with.
247 : */
248 1 : void connect()
249 : {
250 1 : char const * error_name(nullptr);
251 : try
252 : {
253 3 : f_messenger = std::make_shared<messenger>(
254 2 : f_parent_impl->parent()
255 : , f_address
256 : , f_blocking
257 1 : , f_close_on_exec);
258 1 : return;
259 : }
260 0 : catch(event_dispatcher_initialization_error const & e)
261 : {
262 0 : error_name = "event_dispatcher_initialization_error";
263 0 : f_last_error = e.what();
264 : }
265 0 : catch(event_dispatcher_runtime_error const & e)
266 : {
267 0 : error_name = "event_dispatcher_runtime_error";
268 0 : f_last_error = e.what();
269 : }
270 0 : catch(std::exception const & e)
271 : {
272 0 : error_name = "std::exception";
273 0 : f_last_error = e.what();
274 : }
275 0 : catch(...)
276 : {
277 0 : error_name = "... (any other exception)";
278 0 : f_last_error = "Unknown exception";
279 : }
280 0 : f_messenger.reset();
281 :
282 : // connection failed... we will have to try again later
283 : //
284 : // WARNING: our logger is not multi-thread safe quiet yet
285 : //SNAP_LOG_ERROR
286 : // << "connection to "
287 : // << f_address
288 : // << ":"
289 : // << f_port
290 : // << " failed with: "
291 : // << f_last_error
292 : // << " ("
293 : // << error_name
294 : // << ")"
295 : // << SNAP_LOG_SEND;
296 : }
297 :
298 :
299 : /** \brief Retrieve the address to connect to.
300 : *
301 : * This function returns the address passed in on creation.
302 : *
303 : * \note
304 : * Since the variable is constant, it is likely to never change.
305 : * However, the c_str() function may change the buffer pointer.
306 : * Hence, to be 100% safe, you cannot call this function until
307 : * you make sure that the thread is fully stopped.
308 : */
309 0 : addr::unix get_address() const
310 : {
311 0 : return f_address;
312 : }
313 :
314 :
315 : /** \brief Retrieve the client allocated and connected by the thread.
316 : *
317 : * This function returns the TCP connection object resulting from
318 : * connection attempts of the background thread.
319 : *
320 : * If the pointer is null, then you may get the corresponding
321 : * error message using the get_last_error() function.
322 : *
323 : * You can get the client TCP connection pointer once. After that
324 : * you always get a null pointer.
325 : *
326 : * \note
327 : * This function is guarded so the pointer and the object it
328 : * points to will be valid in another thread that retrieves it.
329 : *
330 : * \return The connection pointer.
331 : */
332 1 : messenger::pointer_t release_client()
333 : {
334 2 : cppthread::guard g(f_mutex);
335 1 : messenger::pointer_t release;
336 1 : release.swap(f_messenger);
337 2 : return release;
338 : }
339 :
340 :
341 : /** \brief Retrieve the last error message that happened.
342 : *
343 : * This function returns the last error message that was captured
344 : * when trying to connect to the socket. The message is the
345 : * e.what() message from the exception we captured.
346 : *
347 : * The message does not get cleared so the function can be called
348 : * any number of times. To know whether an error was generated
349 : * on the last attempt, make sure to first get the get_socket()
350 : * and if it returns -1, then this message is significant,
351 : * otherwise it is from a previous error.
352 : *
353 : * \warning
354 : * Remember that if the background thread was used the error will
355 : * NOT be available in the main thread until a full memory barrier
356 : * was executed. For that reason we make sure that the thread
357 : * was stopped when we detect an error.
358 : *
359 : * \return The last error message.
360 : */
361 0 : std::string const & get_last_error() const
362 : {
363 0 : return f_last_error;
364 : }
365 :
366 :
367 : /** \brief Close the connection.
368 : *
369 : * This function closes the connection. Since the f_local_stream_connection
370 : * holds the socket to the remote server, we have get this function
371 : * called in order to completely disconnect.
372 : *
373 : * \note
374 : * This function does not clear the f_last_error parameter so it
375 : * can be read later.
376 : */
377 1 : void close()
378 : {
379 1 : f_messenger.reset();
380 1 : }
381 :
382 :
383 : private:
384 : local_stream_client_permanent_message_connection_impl *
385 : f_parent_impl = nullptr;
386 : addr::unix const f_address;
387 : bool const f_blocking;
388 : bool const f_close_on_exec;
389 : messenger::pointer_t f_messenger = messenger::pointer_t();
390 : std::string f_last_error = std::string();
391 : };
392 :
393 :
394 : /** \brief Initialize a permanent message connection implementation object.
395 : *
396 : * This object manages the thread used to asynchronically connect to
397 : * the specified address and port.
398 : *
399 : * This class and its sub-classes may end up executing callbacks
400 : * of the local_stream_client_permanent_message_connection object.
401 : * However, in all cases these are never run from the thread.
402 : *
403 : * \param[in] client A pointer to the owner of this
404 : * local_stream_client_permanent_message_connection_impl object.
405 : * \param[in] address The address we are to connect to.
406 : * \param[in] port The port we are to connect to.
407 : * \param[in] mode The mode used to connect.
408 : */
409 1 : local_stream_client_permanent_message_connection_impl(
410 : local_stream_client_permanent_message_connection * parent
411 : , addr::unix const & address
412 : , bool const blocking
413 : , bool const close_on_exec)
414 1 : : f_parent(parent)
415 : , f_thread_runner(this, address, blocking, close_on_exec)
416 1 : , f_thread("background connection handler thread", &f_thread_runner)
417 : {
418 1 : }
419 :
420 :
421 : local_stream_client_permanent_message_connection_impl(local_stream_client_permanent_message_connection_impl const & rhs) = delete;
422 : local_stream_client_permanent_message_connection_impl & operator = (local_stream_client_permanent_message_connection_impl const & rhs) = delete;
423 :
424 : /** \brief Destroy the permanent message connection.
425 : *
426 : * This function makes sure that the messenger was lost.
427 : */
428 1 : ~local_stream_client_permanent_message_connection_impl()
429 1 : {
430 : // to make sure we can lose the messenger, first we want to be sure
431 : // that we do not have a thread running
432 : //
433 : try
434 : {
435 1 : f_thread.stop();
436 : }
437 0 : catch(cppthread::cppthread_mutex_failed_error const &)
438 : {
439 : }
440 0 : catch(cppthread::cppthread_invalid_error const &)
441 : {
442 : }
443 :
444 : // in this case we may still have an instance of the f_thread_done
445 : // which linger around, we want it out
446 : //
447 : // Note: the call is safe even if the f_thread_done is null
448 : //
449 1 : communicator::instance()->remove_connection(f_thread_done);
450 :
451 : // although the f_messenger variable gets reset automatically in
452 : // the destructor, it would not get removed from the
453 : // communicator instance if we were not doing it explicitly
454 : //
455 1 : disconnect();
456 1 : }
457 :
458 :
459 : /** \brief Direct connect to the messenger.
460 : *
461 : * In this case we try to connect without the thread. This allows
462 : * us to avoid the thread problems, but we are blocked until the
463 : * OS decides to time out or the connection worked.
464 : */
465 0 : void connect()
466 : {
467 0 : if(f_done)
468 : {
469 0 : SNAP_LOG_ERROR
470 0 : << "Permanent connection marked done. Cannot attempt to reconnect."
471 : << SNAP_LOG_SEND;
472 0 : return;
473 : }
474 :
475 : // call the thread connect() function from the main thread
476 : //
477 0 : f_thread_runner.connect();
478 :
479 : // simulate receiving the thread_done() signal
480 : //
481 0 : thread_done();
482 : }
483 :
484 :
485 : /** \brief Check whether the permanent connection is currently connected.
486 : *
487 : * This function returns true if the messenger exists, which means that
488 : * the connection is up.
489 : *
490 : * \return true if the connection is up.
491 : */
492 0 : bool is_connected()
493 : {
494 0 : return f_messenger != nullptr;
495 : }
496 :
497 :
498 : /** \brief Try to start the thread runner.
499 : *
500 : * This function tries to start the thread runner in order to initiate
501 : * a connection in the background. If the thread could not be started,
502 : * then the function returns false.
503 : *
504 : * If the thread started, then the function returns true. This does
505 : * not mean that the connection was obtained. This is known once
506 : * the process_connected() function is called.
507 : *
508 : * \return true if the thread was successfully started.
509 : */
510 1 : bool background_connect()
511 : {
512 1 : if(f_done)
513 : {
514 0 : SNAP_LOG_ERROR
515 0 : << "Permanent connection marked done. Cannot attempt to reconnect."
516 : << SNAP_LOG_SEND;
517 0 : return false;
518 : }
519 :
520 1 : if(f_thread.is_running())
521 : {
522 0 : SNAP_LOG_ERROR
523 0 : << "A background connection attempt is already in progress. Further requests are ignored."
524 : << SNAP_LOG_SEND;
525 0 : return false;
526 : }
527 :
528 : // create the f_thread_done only when required
529 : //
530 1 : if(f_thread_done == nullptr)
531 : {
532 1 : f_thread_done = std::make_shared<thread_signal_handler>(this);
533 : }
534 :
535 1 : communicator::instance()->add_connection(f_thread_done);
536 :
537 1 : if(!f_thread.start())
538 : {
539 0 : SNAP_LOG_ERROR
540 0 : << "The thread used to run the background connection process did not start."
541 : << SNAP_LOG_SEND;
542 0 : return false;
543 : }
544 :
545 1 : return true;
546 : }
547 :
548 :
549 : /** \brief Tell the main thread that the background thread is done.
550 : *
551 : * This function is called by the thread so the thread_done()
552 : * function of the thread done object gets called. Only the
553 : * thread should call this function.
554 : *
555 : * As a result the thread_done() function of this class will be
556 : * called by the main thread.
557 : */
558 1 : void trigger_thread_done()
559 : {
560 1 : f_thread_done->thread_done();
561 1 : }
562 :
563 :
564 : /** \brief Signal that the background thread is done.
565 : *
566 : * This callback is called whenever the background thread sends
567 : * a signal to us. This is used to avoid calling end user functions
568 : * that would certainly cause a lot of problem if called from the
569 : * thread.
570 : *
571 : * The function calls the process_connection_failed() if the
572 : * connection did not happen.
573 : *
574 : * The function calls the process_connected() if the connection
575 : * did happen.
576 : *
577 : * \note
578 : * This is used only if the user requested that the connection
579 : * happen in the background (i.e. use_thread was set to true
580 : * in the local_stream_client_permanent_message_connection object
581 : * constructor.)
582 : */
583 1 : void thread_done()
584 : {
585 : // if we used the thread we have to remove the signal used
586 : // to know that the thread was done
587 : //
588 1 : communicator::instance()->remove_connection(f_thread_done);
589 :
590 : // we will access the f_last_error member of the thread runner
591 : // which may not be available to the main thread yet, calling
592 : // stop forces a memory barrier so we are all good.
593 : //
594 : // calling stop() has no effect if we did not use the thread,
595 : // however, not calling stop() when we did use the thread
596 : // causes all sorts of other problems (especially, the thread
597 : // never gets joined)
598 : //
599 1 : f_thread.stop();
600 :
601 2 : messenger::pointer_t client(f_thread_runner.release_client());
602 1 : if(f_done)
603 : {
604 : // already marked done, ignore the result and lose the
605 : // connection immediately
606 : //
607 : //f_thread_running.close(); -- not necessary, 'client' is the connection
608 0 : return;
609 : }
610 :
611 1 : if(client == nullptr)
612 : {
613 : // TODO: fix address in error message using a snap::addr so
614 : // as to handle IPv6 seamlessly.
615 : //
616 0 : SNAP_LOG_ERROR
617 0 : << "connection to "
618 0 : << f_thread_runner.get_address().to_uri()
619 : << " failed with: "
620 0 : << f_thread_runner.get_last_error()
621 : << SNAP_LOG_SEND;
622 :
623 : // signal that an error occurred
624 : //
625 0 : f_parent->process_connection_failed(f_thread_runner.get_last_error());
626 : }
627 : else
628 : {
629 1 : f_messenger = client;
630 :
631 : // add the messenger to the communicator
632 : //
633 1 : communicator::instance()->add_connection(f_messenger);
634 :
635 : // if some messages were cached, process them immediately
636 : //
637 3 : while(!f_message_cache.empty())
638 : {
639 1 : f_messenger->send_message(f_message_cache[0]);
640 1 : f_message_cache.erase(f_message_cache.begin());
641 : }
642 :
643 : // let the client know we are now connected
644 : //
645 1 : f_parent->process_connected();
646 : }
647 : }
648 :
649 : /** \brief Send a message to the connection.
650 : *
651 : * This implementation function actually sends the message to the
652 : * connection, assuming that the connection exists. Otherwise, it
653 : * may cache the message (if cache is true.)
654 : *
655 : * Note that the message does not get cached if mark_done() was
656 : * called earlier since we are trying to close the whole connection.
657 : *
658 : * \param[in] message The message to send.
659 : * \param[in] cache Whether to cache the message if the connection is
660 : * currently down.
661 : *
662 : * \return true if the message was forwarded, false if the message
663 : * was ignored or cached.
664 : */
665 2 : bool send_message(message const & msg, bool cache)
666 : {
667 2 : if(f_messenger != nullptr)
668 : {
669 1 : return f_messenger->send_message(msg);
670 : }
671 :
672 1 : if(cache && !f_done)
673 : {
674 1 : f_message_cache.push_back(msg);
675 : }
676 :
677 1 : return false;
678 : }
679 :
680 :
681 : /** \brief Forget about the messenger connection.
682 : *
683 : * This function is used to fully disconnect from the messenger.
684 : *
685 : * If there is a messenger, this means:
686 : *
687 : * \li Removing the messenger from the communicator instance.
688 : * \li Closing the connection in the thread object.
689 : *
690 : * In most cases, it is called when an error occur, also it happens
691 : * that we call it explicitly through the disconnect() function
692 : * of the permanent connection class.
693 : *
694 : * \note
695 : * This is safe, even though it is called from the messenger itself
696 : * because it will not get deleted yet. This is because the run()
697 : * loop has a copy in its own temporary copy of the vector of
698 : * connections.
699 : */
700 2 : void disconnect()
701 : {
702 2 : if(f_messenger != nullptr)
703 : {
704 1 : communicator::instance()->remove_connection(f_messenger);
705 1 : f_messenger.reset();
706 :
707 : // just the messenger does not close the TCP connection because
708 : // we may have another in the thread runner
709 : //
710 1 : f_thread_runner.close();
711 : }
712 2 : }
713 :
714 :
715 : /** \brief Return the address and size of the remote computer.
716 : *
717 : * This function retrieve the socket address.
718 : *
719 : * \warning
720 : * If the socket is not currently connected, the function returns
721 : * a default Unix address. This means it returns a valid unnamed
722 : * address.
723 : *
724 : * \return The Unix address used to connect.
725 : */
726 0 : addr::unix get_address() const
727 : {
728 0 : if(f_messenger != nullptr)
729 : {
730 0 : return f_messenger->get_address();
731 : }
732 0 : return addr::unix();
733 : }
734 :
735 :
736 : /** \brief Mark the messenger as done.
737 : *
738 : * This function is used to mark the messenger as done. This means it
739 : * will get removed from the communicator instance as soon as it
740 : * is done with its current write buffer if there is one.
741 : *
742 : * You may also want to call the disconnection() function to actually
743 : * reset the pointer along the way.
744 : */
745 1 : void mark_done()
746 : {
747 1 : f_done = true;
748 :
749 : // once done we don't attempt to reconnect so we can as well
750 : // get rid of our existing cache immediately to save some
751 : // memory
752 : //
753 1 : f_message_cache.clear();
754 :
755 1 : if(f_messenger != nullptr)
756 : {
757 1 : f_messenger->mark_done();
758 : }
759 1 : }
760 :
761 :
762 : /** \brief Retrieve the parent of the impl.
763 : *
764 : * This function returns the parent of the impl, which is the main
765 : * local_stream_client_permanent_message_connection point. This is
766 : * saved in the messenger so we can relay events from our internal
767 : * messenger implementation to the main class owned by the user.
768 : *
769 : * \return The pointer to the parent of the impl.
770 : */
771 1 : local_stream_client_permanent_message_connection * parent() const
772 : {
773 1 : return f_parent;
774 : }
775 :
776 :
777 : private:
778 : local_stream_client_permanent_message_connection *
779 : f_parent = nullptr;
780 : thread_signal_handler::pointer_t f_thread_done = thread_signal_handler::pointer_t();
781 : runner f_thread_runner;
782 : cppthread::thread f_thread;
783 : messenger::pointer_t f_messenger = messenger::pointer_t();
784 : message::vector_t f_message_cache = message::vector_t();
785 : bool f_done = false;
786 : };
787 :
788 :
789 :
790 : }
791 : // namespace detail
792 :
793 :
794 :
795 : /** \brief Initializes this TCP client message connection.
796 : *
797 : * This implementation creates what we call a permanent connection.
798 : * Such a connection may fail once in a while. In such circumstances,
799 : * the class automatically requests for a reconnection (see various
800 : * parameters in the regard below.) However, this causes one issue:
801 : * by default, the connection just never ends. When you are about
802 : * ready to close the connection, you must call the mark_done()
803 : * function first. This will tell the various error functions to
804 : * drop this connection instead of restarting it after a small pause.
805 : *
806 : * This constructor makes sure to initialize the timer and saves
807 : * the address, port, mode, pause, and use_thread parameters.
808 : *
809 : * The timer is first set to trigger immediately. This means the TCP
810 : * connection will be attempted as soon as possible (the next time
811 : * the run() loop is entered, it will time out immediately.) You
812 : * are free to call set_timeout_date() with a date in the future if
813 : * you prefer that the connect be attempted a little later.
814 : *
815 : * The \p pause parameter is used if the connection is lost and this
816 : * timer is used again to attempt a new connection. It will be reused
817 : * as long as the connection fails (as a delay). It has to be at least
818 : * 10 microseconds, although really you should not use less than 1
819 : * second (1000000). You may set the pause parameter to 0 in which case
820 : * you are responsible to set the delay (by default there will be no
821 : * delay and thus the timer will never time out.)
822 : *
823 : * To start with a delay, instead of trying to connect immediately,
824 : * you may pass a negative pause parameter. So for example to get the
825 : * first attempt 5 seconds after you created this object, you use
826 : * -5000000LL as the pause parameter.
827 : *
828 : * The \p use_thread parameter determines whether the connection should
829 : * be attempted in a thread (asynchronously) or immediately (which means
830 : * the timeout callback may block for a while.) If the connection is to
831 : * a local server with an IP address specified as numbers (i.e. 127.0.0.1),
832 : * the thread is probably not required. For connections to a remote
833 : * computer, though, it certainly is important.
834 : *
835 : * \param[in] address The address to listen on. It may be set to "0.0.0.0".
836 : * \param[in] port The port to listen on.
837 : * \param[in] mode The mode to use to open the connection.
838 : * \param[in] pause The amount of time to wait before attempting a new
839 : * connection after a failure, in microseconds, or 0.
840 : * \param[in] use_thread Whether a thread is used to connect to the
841 : * server.
842 : */
843 1 : local_stream_client_permanent_message_connection::local_stream_client_permanent_message_connection(
844 : addr::unix const & address
845 : , std::int64_t const pause
846 : , bool const use_thread
847 : , bool const blocking
848 1 : , bool const close_on_exec)
849 : : timer(pause < 0 ? -pause : 0)
850 : , f_impl(std::make_shared<detail::local_stream_client_permanent_message_connection_impl>(
851 : this
852 : , address
853 : , blocking
854 : , close_on_exec))
855 1 : , f_pause(llabs(pause))
856 2 : , f_use_thread(use_thread)
857 : {
858 1 : }
859 :
860 :
861 : /** \brief Destroy instance.
862 : *
863 : * This function cleans up everything in the permanent message object.
864 : */
865 1 : local_stream_client_permanent_message_connection::~local_stream_client_permanent_message_connection()
866 : {
867 : // Does nothing
868 1 : }
869 :
870 :
871 : /** \brief Attempt to send a message to this connection.
872 : *
873 : * If the connection is currently enabled, the message is sent immediately.
874 : * Otherwise, it may be cached if the \p cache parameter is set to true.
875 : * A cached message is forwarded as soon as a new successful connection
876 : * happens, which can be a problem if messages need to happen in a very
877 : * specific order (For example, after a reconnection to snapcommunicator
878 : * you first need to REGISTER or CONNECT...)
879 : *
880 : * \param[in] message The message to send to the connected server.
881 : * \param[in] cache Whether the message should be cached.
882 : *
883 : * \return true if the message was sent, false if it was not sent, although
884 : * if cache was true, it was cached
885 : */
886 2 : bool local_stream_client_permanent_message_connection::send_message(message const & msg, bool cache)
887 : {
888 2 : return f_impl->send_message(msg, cache);
889 : }
890 :
891 :
892 : /** \brief Check whether the connection is up.
893 : *
894 : * This function returns true if the connection is considered to be up.
895 : * This means sending messages will work quickly instead of being
896 : * cached up until an actual TCP/IP connection gets established.
897 : *
898 : * Note that the connection may have hanged up since, and the system
899 : * may not have yet detected the fact (i.e. the connection is going
900 : * to receive the process_hup() call after the event in which you are
901 : * working.)
902 : *
903 : * \return true if connected
904 : */
905 0 : bool local_stream_client_permanent_message_connection::is_connected() const
906 : {
907 0 : return f_impl->is_connected();
908 : }
909 :
910 :
911 : /** \brief Disconnect the messenger now.
912 : *
913 : * This function kills the current connection.
914 : *
915 : * There are a few cases where two daemons communicate between each others
916 : * and at some point one of them wants to exit and needs to disconnect. This
917 : * function can be used in that one situation assuming that you have an
918 : * acknowledgement from the other daemon.
919 : *
920 : * Say you have daemon A and B. B wants to quit and before doing so sends
921 : * a form of "I'm quitting" message to A. In that situation, B is not closing
922 : * the messenger connection, A is responsible for that (i.e. A acknowledges
923 : * receipt of the "I'm quitting" message from B by closing the connection.)
924 : *
925 : * B also wants to call the mark_done() function to make sure that it
926 : * does not reconnected a split second later and instead the permanent
927 : * connection gets removed from the communicator list of connections.
928 : */
929 0 : void local_stream_client_permanent_message_connection::disconnect()
930 : {
931 0 : f_impl->disconnect();
932 0 : }
933 :
934 :
935 : /** \brief Overload so we do not have to use namespace everywhere.
936 : *
937 : * This function overloads the connection::mark_done() function so
938 : * we can call it without the need to use timer::mark_done()
939 : * everywhere.
940 : */
941 0 : void local_stream_client_permanent_message_connection::mark_done()
942 : {
943 0 : timer::mark_done();
944 0 : }
945 :
946 :
947 : /** \brief Mark connection as done.
948 : *
949 : * This function allows you to mark the permanent connection and the
950 : * messenger as done.
951 : *
952 : * Note that calling this function with false is the same as calling the
953 : * base class mark_done() function.
954 : *
955 : * If the \p message parameter is set to true, we suggest you also call
956 : * the disconnect() function. That way the messenger will truly get
957 : * removed from everyone quickly.
958 : *
959 : * \param[in] messenger If true, also mark the messenger as done.
960 : */
961 1 : void local_stream_client_permanent_message_connection::mark_done(bool messenger)
962 : {
963 1 : timer::mark_done();
964 1 : if(messenger)
965 : {
966 1 : f_impl->mark_done();
967 : }
968 1 : }
969 :
970 :
971 : /** \brief Retrieve a copy of the client's address.
972 : *
973 : * This function makes a copy of the address of this client connection
974 : * to the \p address parameter and returns the length.
975 : *
976 : * \return Return a copy of the Unix address.
977 : */
978 0 : addr::unix local_stream_client_permanent_message_connection::get_address() const
979 : {
980 0 : return f_impl->get_address();
981 : }
982 :
983 :
984 : /** \brief Internal timeout callback implementation.
985 : *
986 : * This callback implements the guts of this class: it attempts to connect
987 : * to the specified address and port, optionally after creating a thread
988 : * so the attempt can happen asynchronously.
989 : *
990 : * When the connection fails, the timer is used to try again pause
991 : * microseconds later (pause as specified in the constructor).
992 : *
993 : * When a connection succeeds, the timer is disabled until you detect
994 : * an error while using the connection and re-enable the timer.
995 : *
996 : * \warning
997 : * This function changes the timeout delay to the pause amount
998 : * as defined with the constructor. If you want to change that
999 : * amount, you can do so an any point after this function call
1000 : * using the set_timeout_delay() function. If the pause parameter
1001 : * was set to -1, then the timeout never gets changed.
1002 : * However, you should not use a permanent message timer as your
1003 : * own or you will interfere with the internal use of the timer.
1004 : */
1005 1 : void local_stream_client_permanent_message_connection::process_timeout()
1006 : {
1007 : // got a spurious call when already marked done
1008 : //
1009 1 : if(is_done())
1010 : {
1011 0 : return;
1012 : }
1013 :
1014 : // change the timeout delay although we will not use it immediately
1015 : // if we start the thread or attempt an immediate connection, but
1016 : // that way the user can change it by calling set_timeout_delay()
1017 : // at any time after the first process_timeout() call
1018 : //
1019 1 : if(f_pause > 0)
1020 : {
1021 1 : set_timeout_delay(f_pause);
1022 1 : f_pause = 0;
1023 : }
1024 :
1025 1 : if(f_use_thread)
1026 : {
1027 : // in this case we create a thread, run it and know whether the
1028 : // connection succeeded only when the thread tells us it did
1029 : //
1030 : // TODO: the background_connect() may return false in two situations:
1031 : // 1) when the thread is already running and then the behavior
1032 : // we have below is INCORRECT
1033 : // 2) when the thread cannot be started (i.e. could not
1034 : // allocate the stack?) in which case the if() below
1035 : // is the correct behavior
1036 : //
1037 1 : if(f_impl->background_connect())
1038 : {
1039 : // we started the thread successfully, so block the timer
1040 : //
1041 1 : set_enable(false);
1042 : }
1043 : }
1044 : else
1045 : {
1046 : // the success is noted when we receive a call to
1047 : // process_connected(); there we do set_enable(false)
1048 : // so the timer stops
1049 : //
1050 0 : f_impl->connect();
1051 : }
1052 : }
1053 :
1054 :
1055 : /** \brief Process an error.
1056 : *
1057 : * When an error occurs, we restart the timer so we can attempt to reconnect
1058 : * to that server.
1059 : *
1060 : * If you overload this function, make sure to either call this
1061 : * implementation or enable the timer yourselves.
1062 : *
1063 : * \warning
1064 : * This function does not call the timer::process_error() function
1065 : * which means that this connection is not automatically removed from
1066 : * the communicator object on failures.
1067 : */
1068 0 : void local_stream_client_permanent_message_connection::process_error()
1069 : {
1070 0 : if(is_done())
1071 : {
1072 0 : timer::process_error();
1073 : }
1074 : else
1075 : {
1076 0 : f_impl->disconnect();
1077 0 : set_enable(true);
1078 : }
1079 0 : }
1080 :
1081 :
1082 : /** \brief Process a hang up.
1083 : *
1084 : * When a hang up occurs, we restart the timer so we can attempt to reconnect
1085 : * to that server.
1086 : *
1087 : * If you overload this function, make sure to either call this
1088 : * implementation or enable the timer yourselves.
1089 : *
1090 : * \warning
1091 : * This function does not call the timer::process_hup() function
1092 : * which means that this connection is not automatically removed from
1093 : * the communicator object on failures.
1094 : */
1095 0 : void local_stream_client_permanent_message_connection::process_hup()
1096 : {
1097 0 : if(is_done())
1098 : {
1099 0 : timer::process_hup();
1100 : }
1101 : else
1102 : {
1103 0 : f_impl->disconnect();
1104 0 : set_enable(true);
1105 : }
1106 0 : }
1107 :
1108 :
1109 : /** \brief Process an invalid signal.
1110 : *
1111 : * When an invalid signal occurs, we restart the timer so we can attempt
1112 : * to reconnect to that server.
1113 : *
1114 : * If you overload this function, make sure to either call this
1115 : * implementation or enable the timer yourselves.
1116 : *
1117 : * \warning
1118 : * This function does not call the timer::process_invalid() function
1119 : * which means that this connection is not automatically removed from
1120 : * the communicator object on failures.
1121 : */
1122 0 : void local_stream_client_permanent_message_connection::process_invalid()
1123 : {
1124 0 : if(is_done())
1125 : {
1126 0 : timer::process_invalid();
1127 : }
1128 : else
1129 : {
1130 0 : f_impl->disconnect();
1131 0 : set_enable(true);
1132 : }
1133 0 : }
1134 :
1135 :
1136 : /** \brief Make sure that the messenger connection gets removed.
1137 : *
1138 : * This function makes sure that the messenger sub-connection also gets
1139 : * removed from the communicator. Otherwise it would lock the system
1140 : * since connections are saved in the communicator object as shared
1141 : * pointers.
1142 : */
1143 1 : void local_stream_client_permanent_message_connection::connection_removed()
1144 : {
1145 1 : f_impl->disconnect();
1146 1 : }
1147 :
1148 :
1149 : /** \brief Process a connection failed callback.
1150 : *
1151 : * When a connection attempt fails, we restart the timer so we can
1152 : * attempt to reconnect to that server.
1153 : *
1154 : * If you overload this function, make sure to either call this
1155 : * implementation or enable the timer yourselves.
1156 : *
1157 : * \param[in] error_message The error message that triggered this callback.
1158 : */
1159 0 : void local_stream_client_permanent_message_connection::process_connection_failed(std::string const & error_message)
1160 : {
1161 0 : snap::NOT_USED(error_message);
1162 0 : set_enable(true);
1163 0 : }
1164 :
1165 :
1166 : /** \brief The connection is ready.
1167 : *
1168 : * This callback gets called whenever the connection succeeded and is
1169 : * ready to be used.
1170 : *
1171 : * You should implement this virtual function if you have to initiate
1172 : * the communication. For example, the snapserver has to send a
1173 : * REGISTER to the snapcommunicator system and thus implements this
1174 : * function.
1175 : *
1176 : * The default implementation makes sure that the timer gets turned off
1177 : * so we do not try to reconnect every minute or so. Make sure you call
1178 : * the default function so you get the proper behavior.
1179 : */
1180 1 : void local_stream_client_permanent_message_connection::process_connected()
1181 : {
1182 1 : set_enable(false);
1183 1 : }
1184 :
1185 :
1186 :
1187 6 : } // namespace ed
1188 : // vim: ts=4 sw=4 et
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