Mercurial > sdl-ios-xcode
annotate docs/html/thread.html @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 05 Jan 2004 00:57:51 +0000 |
parents | e5bc29de3f0a |
children | 355632dca928 |
rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >Multi-threaded Programming</TITLE | |
5 ><META | |
6 NAME="GENERATOR" | |
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.64 |
0 | 8 "><LINK |
9 REL="HOME" | |
10 TITLE="SDL Library Documentation" | |
11 HREF="index.html"><LINK | |
12 REL="UP" | |
13 TITLE="SDL Reference" | |
14 HREF="reference.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="SDL_CDtrack" | |
17 HREF="sdlcdtrack.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_CreateThread" | |
20 HREF="sdlcreatethread.html"><META | |
21 NAME="KEYWORD" | |
22 CONTENT="threads"><META | |
23 NAME="KEYWORD" | |
24 CONTENT="function"></HEAD | |
25 ><BODY | |
26 CLASS="CHAPTER" | |
27 BGCOLOR="#FFF8DC" | |
28 TEXT="#000000" | |
29 LINK="#0000ee" | |
30 VLINK="#551a8b" | |
31 ALINK="#ff0000" | |
32 ><DIV | |
33 CLASS="NAVHEADER" | |
34 ><TABLE | |
35 WIDTH="100%" | |
36 BORDER="0" | |
37 CELLPADDING="0" | |
38 CELLSPACING="0" | |
39 ><TR | |
40 ><TH | |
41 COLSPAN="3" | |
42 ALIGN="center" | |
43 >SDL Library Documentation</TH | |
44 ></TR | |
45 ><TR | |
46 ><TD | |
47 WIDTH="10%" | |
48 ALIGN="left" | |
49 VALIGN="bottom" | |
50 ><A | |
51 HREF="sdlcdtrack.html" | |
52 >Prev</A | |
53 ></TD | |
54 ><TD | |
55 WIDTH="80%" | |
56 ALIGN="center" | |
57 VALIGN="bottom" | |
58 ></TD | |
59 ><TD | |
60 WIDTH="10%" | |
61 ALIGN="right" | |
62 VALIGN="bottom" | |
63 ><A | |
64 HREF="sdlcreatethread.html" | |
65 >Next</A | |
66 ></TD | |
67 ></TR | |
68 ></TABLE | |
69 ><HR | |
70 ALIGN="LEFT" | |
71 WIDTH="100%"></DIV | |
72 ><DIV | |
73 CLASS="CHAPTER" | |
74 ><H1 | |
75 ><A | |
76 NAME="THREAD" | |
77 >Chapter 12. Multi-threaded Programming</A | |
78 ></H1 | |
79 ><DIV | |
80 CLASS="TOC" | |
81 ><DL | |
82 ><DT | |
83 ><B | |
84 >Table of Contents</B | |
85 ></DT | |
86 ><DT | |
87 ><A | |
88 HREF="sdlcreatethread.html" | |
89 >SDL_CreateThread</A | |
90 > — Creates a new thread of execution that shares its parent's properties.</DT | |
91 ><DT | |
92 ><A | |
93 HREF="sdlthreadid.html" | |
94 >SDL_ThreadID</A | |
95 > — Get the 32-bit thread identifier for the current thread.</DT | |
96 ><DT | |
97 ><A | |
98 HREF="sdlgetthreadid.html" | |
99 >SDL_GetThreadID</A | |
100 > — Get the SDL thread ID of a SDL_Thread</DT | |
101 ><DT | |
102 ><A | |
103 HREF="sdlwaitthread.html" | |
104 >SDL_WaitThread</A | |
105 > — Wait for a thread to finish.</DT | |
106 ><DT | |
107 ><A | |
108 HREF="sdlkillthread.html" | |
109 >SDL_KillThread</A | |
110 > — Gracelessly terminates the thread.</DT | |
111 ><DT | |
112 ><A | |
113 HREF="sdlcreatemutex.html" | |
114 >SDL_CreateMutex</A | |
115 > — Create a mutex</DT | |
116 ><DT | |
117 ><A | |
118 HREF="sdldestroymutex.html" | |
119 >SDL_DestroyMutex</A | |
120 > — Destroy a mutex</DT | |
121 ><DT | |
122 ><A | |
123 HREF="sdlmutexp.html" | |
124 >SDL_mutexP</A | |
125 > — Lock a mutex</DT | |
126 ><DT | |
127 ><A | |
128 HREF="sdlmutexv.html" | |
129 >SDL_mutexV</A | |
130 > — Unlock a mutex</DT | |
131 ><DT | |
132 ><A | |
133 HREF="sdlcreatesemaphore.html" | |
134 >SDL_CreateSemaphore</A | |
135 > — Creates a new semaphore and assigns an initial value to it.</DT | |
136 ><DT | |
137 ><A | |
138 HREF="sdldestroysemaphore.html" | |
139 >SDL_DestroySemaphore</A | |
140 > — Destroys a semaphore that was created by <A | |
141 HREF="sdlcreatesemaphore.html" | |
142 >SDL_CreateSemaphore</A | |
143 >.</DT | |
144 ><DT | |
145 ><A | |
146 HREF="sdlsemwait.html" | |
147 >SDL_SemWait</A | |
148 > — Lock a semaphore and suspend the thread if the semaphore value is zero.</DT | |
149 ><DT | |
150 ><A | |
151 HREF="sdlsemtrywait.html" | |
152 >SDL_SemTryWait</A | |
153 > — Attempt to lock a semaphore but don't suspend the thread.</DT | |
154 ><DT | |
155 ><A | |
156 HREF="sdlsemwaittimeout.html" | |
157 >SDL_SemWaitTimeout</A | |
158 > — Lock a semaphore, but only wait up to a specified maximum time.</DT | |
159 ><DT | |
160 ><A | |
161 HREF="sdlsempost.html" | |
162 >SDL_SemPost</A | |
163 > — Unlock a semaphore.</DT | |
164 ><DT | |
165 ><A | |
166 HREF="sdlsemvalue.html" | |
167 >SDL_SemValue</A | |
168 > — Return the current value of a semaphore.</DT | |
169 ><DT | |
170 ><A | |
171 HREF="sdlcreatecond.html" | |
172 >SDL_CreateCond</A | |
173 > — Create a condition variable</DT | |
174 ><DT | |
175 ><A | |
176 HREF="sdldestroycond.html" | |
177 >SDL_DestroyCond</A | |
178 > — Destroy a condition variable</DT | |
179 ><DT | |
180 ><A | |
181 HREF="sdlcondsignal.html" | |
182 >SDL_CondSignal</A | |
183 > — Restart a thread wait on a condition variable</DT | |
184 ><DT | |
185 ><A | |
186 HREF="sdlcondbroadcast.html" | |
187 >SDL_CondBroadcast</A | |
188 > — Restart all threads waiting on a condition variable</DT | |
189 ><DT | |
190 ><A | |
191 HREF="sdlcondwait.html" | |
192 >SDL_CondWait</A | |
193 > — Wait on a condition variable</DT | |
194 ><DT | |
195 ><A | |
196 HREF="sdlcondwaittimeout.html" | |
197 >SDL_CondWaitTimeout</A | |
198 > — Wait on a condition variable, with timeout</DT | |
199 ></DL | |
200 ></DIV | |
201 ><P | |
202 >SDL provides functions for creating threads, mutexes, semphores and condition variables.</P | |
203 ><P | |
204 >In general, you must be very aware of concurrency and data integrity issues | |
205 when writing multi-threaded programs. Some good guidelines include: | |
206 <P | |
207 ></P | |
208 ><UL | |
209 ><LI | |
210 ><P | |
211 >Don't call SDL video/event functions from separate threads</P | |
212 ></LI | |
213 ><LI | |
214 ><P | |
215 >Don't use any library functions in separate threads</P | |
216 ></LI | |
217 ><LI | |
218 ><P | |
219 >Don't perform any memory management in separate threads</P | |
220 ></LI | |
221 ><LI | |
222 ><P | |
223 >Lock global variables which may be accessed by multiple threads</P | |
224 ></LI | |
225 ><LI | |
226 ><P | |
227 >Never terminate threads, always set a flag and wait for them to quit</P | |
228 ></LI | |
229 ><LI | |
230 ><P | |
231 >Think very carefully about all possible ways your code may interact</P | |
232 ></LI | |
233 ></UL | |
234 ></P | |
235 ><DIV | |
236 CLASS="NOTE" | |
237 ><BLOCKQUOTE | |
238 CLASS="NOTE" | |
239 ><P | |
240 ><B | |
241 >Note: </B | |
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
242 >SDL's threading is not implemented on MacOS, due to that lack of preemptive thread support (MacOS X dos nt suffer from this problem)</P |
0 | 243 ></BLOCKQUOTE |
244 ></DIV | |
245 ></DIV | |
246 ><DIV | |
247 CLASS="NAVFOOTER" | |
248 ><HR | |
249 ALIGN="LEFT" | |
250 WIDTH="100%"><TABLE | |
251 WIDTH="100%" | |
252 BORDER="0" | |
253 CELLPADDING="0" | |
254 CELLSPACING="0" | |
255 ><TR | |
256 ><TD | |
257 WIDTH="33%" | |
258 ALIGN="left" | |
259 VALIGN="top" | |
260 ><A | |
261 HREF="sdlcdtrack.html" | |
262 >Prev</A | |
263 ></TD | |
264 ><TD | |
265 WIDTH="34%" | |
266 ALIGN="center" | |
267 VALIGN="top" | |
268 ><A | |
269 HREF="index.html" | |
270 >Home</A | |
271 ></TD | |
272 ><TD | |
273 WIDTH="33%" | |
274 ALIGN="right" | |
275 VALIGN="top" | |
276 ><A | |
277 HREF="sdlcreatethread.html" | |
278 >Next</A | |
279 ></TD | |
280 ></TR | |
281 ><TR | |
282 ><TD | |
283 WIDTH="33%" | |
284 ALIGN="left" | |
285 VALIGN="top" | |
286 >SDL_CDtrack</TD | |
287 ><TD | |
288 WIDTH="34%" | |
289 ALIGN="center" | |
290 VALIGN="top" | |
291 ><A | |
292 HREF="reference.html" | |
293 >Up</A | |
294 ></TD | |
295 ><TD | |
296 WIDTH="33%" | |
297 ALIGN="right" | |
298 VALIGN="top" | |
299 >SDL_CreateThread</TD | |
300 ></TR | |
301 ></TABLE | |
302 ></DIV | |
303 ></BODY | |
304 ></HTML | |
305 > |