1 //////////////////////////////////////////////////////////////////////// 2 // 3 // Copyright (C) 2012-2021 The Octave Project Developers 4 // 5 // See the file COPYRIGHT.md in the top-level directory of this 6 // distribution or <https://octave.org/copyright/>. 7 // 8 // This file is part of Octave. 9 // 10 // Octave is free software: you can redistribute it and/or modify it 11 // under the terms of the GNU General Public License as published by 12 // the Free Software Foundation, either version 3 of the License, or 13 // (at your option) any later version. 14 // 15 // Octave is distributed in the hope that it will be useful, but 16 // WITHOUT ANY WARRANTY; without even the implied warranty of 17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 // GNU General Public License for more details. 19 // 20 // You should have received a copy of the GNU General Public License 21 // along with Octave; see the file COPYING. If not, see 22 // <https://www.gnu.org/licenses/>. 23 // 24 //////////////////////////////////////////////////////////////////////// 25 26 #if ! defined (octave_event_queue_h) 27 #define octave_event_queue_h 1 28 29 #include "octave-config.h" 30 31 #include <queue> 32 #include <memory> 33 34 #include "action-container.h" 35 36 namespace octave 37 { 38 class 39 event_queue : public action_container 40 { 41 public: 42 event_queue(void)43 event_queue (void) : fifo () { } 44 45 // No copying! 46 47 event_queue (const event_queue&) = delete; 48 49 event_queue& operator = (const event_queue&) = delete; 50 51 // Destructor should not raise an exception, so all actions 52 // registered should be exception-safe. If you're not sure, see 53 // event_queue_safe. 54 ~event_queue(void)55 ~event_queue (void) { run (); } 56 run_first(void)57 void run_first (void) 58 { 59 if (! empty ()) 60 { 61 // No leak on exception! 62 std::unique_ptr<elem> ptr (fifo.front ()); 63 fifo.pop (); 64 ptr->run (); 65 } 66 } 67 discard_first(void)68 void discard_first (void) 69 { 70 if (! empty ()) 71 { 72 elem *ptr = fifo.front (); 73 fifo.pop (); 74 delete ptr; 75 } 76 } 77 size(void)78 std::size_t size (void) const { return fifo.size (); } 79 80 protected: 81 add_action(elem * new_elem)82 void add_action (elem *new_elem) 83 { 84 fifo.push (new_elem); 85 } 86 87 std::queue<elem *> fifo; 88 }; 89 90 // Like event_queue, but this one will guard against the 91 // possibility of seeing an exception (or interrupt) in the cleanup actions. 92 // Not that we can do much about it, but at least we won't crash. 93 94 class 95 event_queue_safe : public event_queue 96 { 97 private: 98 99 void warn_unhandled_exception (void) const; 100 101 public: 102 event_queue_safe(void)103 event_queue_safe (void) : event_queue () { } 104 105 // No copying! 106 107 event_queue_safe (const event_queue_safe&) = delete; 108 109 event_queue_safe& operator = (const event_queue_safe&) = delete; 110 ~event_queue_safe(void)111 ~event_queue_safe (void) 112 { 113 while (! empty ()) 114 { 115 try 116 { 117 run_first (); 118 } 119 catch (...) // Yes, the black hole. Remember we're in a dtor. 120 { 121 warn_unhandled_exception (); 122 } 123 } 124 } 125 }; 126 } 127 128 #endif 129