annotate src/thread/generic/SDL_sysmutex.c @ 1629:ef4a796e7f24

Fixed bug #55 From Christian Walther: When writing my patch for #12, I ended up doing all sorts of changes to the way application/window activating/deactivating is handled in the Quartz backend, resulting in the attached patch. It does make the code a bit cleaner IMHO, but as it might be regarded as a case of "if it ain't broken, don't fix it" I'd like to hear other people's opinion about it. Please shout if some change strikes you as unnecessary or wrong, and I'll explain the reasons behind it. As far as I tested it, it does not introduce any new bugs, but I may well have missed some. - The most fundamental change (that triggered most of the others) is irrelevant for the usual single-window SDL applications, it only affects the people who are crazy enough to display other Cocoa windows alongside the SDL window (I'm actually doing this currently, although the additional window only displays debugging info and won't be present in the final product): Before, some things were done on the application becoming active, some on the window becoming key, and some on the window becoming main. Conceptually, all these actions belong to the window becoming key, so that's what I implemented. However, since in a single-window application these three events always happen together, the previous implementation "ain't broken". - This slightly changed the meaning of the SDL_APPMOUSEFOCUS flag from SDL_GetAppState(): Before, it meant "window is main and mouse is inside window (or mode is fullscreen)". Now, it means "window is key and mouse is inside window (or mode is fullscreen)". It makes more sense to me that way. (See http://developer.apple.com/documentation/Cocoa/Conceptual/WinPanel/Concepts/ChangingMainKeyWindow.html for a discussion of what key and main windows are.) The other two flags are unchanged: SDL_APPACTIVE = application is not hidden and window is not minimized, SDL_APPINPUTFOCUS = window is key (or mode is fullscreen). - As a side effect, the reorganization fixes the following two issues (and maybe others) (but they could also be fixed in less invasive ways): * A regression that was introduced in revision 1.42 of SDL_QuartzVideo.m (http://libsdl.org/cgi/cvsweb.cgi/SDL12/src/video/quartz/SDL_QuartzVideo.m.diff?r1=1.41&r2=1.42) (from half-desirable to undesirable behavior): Situation: While in windowed mode, hide the cursor using SDL_ShowCursor(SDL_DISABLE), move the mouse outside of the window so that the cursor becomes visible again, and SDL_SetVideoMode() to a fullscreen mode. What happened before revision 1.42: The cursor is visible, but becomes invisible as soon as the mouse is moved (half-desirable). What happens in revision 1.42 and after (including current CVS): The cursor is visible and stays visible (undesirable). What happens after my patch: The cursor is invisible from the beginning (desirable). * When the cursor is hidden and grabbed, switch away from the application using cmd-tab (which ungrabs and makes the cursor visible), move the cursor outside of the SDL window, then cmd-tab back to the application. In 1.2.8 and in the current CVS, the cursor is re-grabbed, but it stays visible (immovable in the middle of the window). With my patch, the cursor is correctly re-grabbed and hidden. (For some reason, it still doesn't work correctly if you switch back to the application using the dock instead of cmd-tab. I haven't been able to figure out why. I can step over [NSCursor hide] being called in the debugger, but it seems to have no effect.) - The patch includes my patch for #12 (it was easier to obtain using cvs diff that way). If you apply both of them, you will end up with 6 duplicate lines in SDL_QuartzEvents.m.
author Sam Lantinga <slouken@libsdl.org>
date Thu, 13 Apr 2006 14:17:48 +0000
parents d910939febfa
children 782fd950bd46 c121d94672cb a1b03ba2fcd0
rev   line source
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997-2006 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Lesser General Public
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7 License as published by the Free Software Foundation; either
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8 version 2.1 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Lesser General Public License for more details.
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14
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15 You should have received a copy of the GNU Lesser General Public
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16 License along with this library; if not, write to the Free Software
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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18
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19 Sam Lantinga
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20 slouken@libsdl.org
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21 */
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22 #include "SDL_config.h"
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23
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24 /* An implementation of mutexes using semaphores */
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25
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26 #include "SDL_thread.h"
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27 #include "SDL_systhread_c.h"
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28
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29
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30 struct SDL_mutex {
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31 int recursive;
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32 Uint32 owner;
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33 SDL_sem *sem;
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34 };
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35
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36 /* Create a mutex */
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37 SDL_mutex *SDL_CreateMutex(void)
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38 {
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39 SDL_mutex *mutex;
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40
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41 /* Allocate mutex memory */
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42 mutex = (SDL_mutex *)SDL_malloc(sizeof(*mutex));
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43 if ( mutex ) {
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44 /* Create the mutex semaphore, with initial value 1 */
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45 mutex->sem = SDL_CreateSemaphore(1);
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46 mutex->recursive = 0;
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47 mutex->owner = 0;
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48 if ( ! mutex->sem ) {
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49 SDL_free(mutex);
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50 mutex = NULL;
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51 }
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52 } else {
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53 SDL_OutOfMemory();
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54 }
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55 return mutex;
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56 }
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57
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58 /* Free the mutex */
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59 void SDL_DestroyMutex(SDL_mutex *mutex)
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60 {
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61 if ( mutex ) {
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62 if ( mutex->sem ) {
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63 SDL_DestroySemaphore(mutex->sem);
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64 }
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65 SDL_free(mutex);
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66 }
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67 }
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68
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69 /* Lock the semaphore */
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70 int SDL_mutexP(SDL_mutex *mutex)
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71 {
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72 #if SDL_THREADS_DISABLED
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73 return 0;
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74 #else
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75 Uint32 this_thread;
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76
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77 if ( mutex == NULL ) {
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78 SDL_SetError("Passed a NULL mutex");
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79 return -1;
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80 }
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81
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82 this_thread = SDL_ThreadID();
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83 if ( mutex->owner == this_thread ) {
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84 ++mutex->recursive;
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85 } else {
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86 /* The order of operations is important.
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87 We set the locking thread id after we obtain the lock
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88 so unlocks from other threads will fail.
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89 */
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90 SDL_SemWait(mutex->sem);
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91 mutex->owner = this_thread;
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92 mutex->recursive = 0;
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93 }
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94
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95 return 0;
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96 #endif /* SDL_THREADS_DISABLED */
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97 }
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98
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99 /* Unlock the mutex */
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100 int SDL_mutexV(SDL_mutex *mutex)
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101 {
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102 #if SDL_THREADS_DISABLED
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103 return 0;
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104 #else
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105 if ( mutex == NULL ) {
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106 SDL_SetError("Passed a NULL mutex");
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107 return -1;
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108 }
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109
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110 /* If we don't own the mutex, we can't unlock it */
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111 if ( SDL_ThreadID() != mutex->owner ) {
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112 SDL_SetError("mutex not owned by this thread");
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113 return -1;
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114 }
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115
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116 if ( mutex->recursive ) {
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117 --mutex->recursive;
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118 } else {
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119 /* The order of operations is important.
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120 First reset the owner so another thread doesn't lock
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121 the mutex and set the ownership before we reset it,
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122 then release the lock semaphore.
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123 */
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124 mutex->owner = 0;
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125 SDL_SemPost(mutex->sem);
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126 }
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127 return 0;
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128 #endif /* SDL_THREADS_DISABLED */
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129 }