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1 | package threads; |
2 | ||
3 | use 5.008; | |
4 | use strict; | |
5 | use warnings; | |
6 | use Config; | |
7 | ||
8 | BEGIN { | |
9 | unless ($Config{useithreads}) { | |
10 | my @caller = caller(2); | |
11 | die <<EOF; | |
12 | $caller[1] line $caller[2]: | |
13 | ||
14 | This Perl hasn't been configured and built properly for the threads | |
15 | module to work. (The 'useithreads' configuration option hasn't been used.) | |
16 | ||
17 | Having threads support requires all of Perl and all of the XS modules in | |
18 | the Perl installation to be rebuilt, it is not just a question of adding | |
19 | the threads module. (In other words, threaded and non-threaded Perls | |
20 | are binary incompatible.) | |
21 | ||
22 | If you want to the use the threads module, please contact the people | |
23 | who built your Perl. | |
24 | ||
25 | Cannot continue, aborting. | |
26 | EOF | |
27 | } | |
28 | } | |
29 | ||
30 | use overload | |
31 | '==' => \&equal, | |
32 | 'fallback' => 1; | |
33 | ||
34 | #use threads::Shared; | |
35 | ||
36 | BEGIN { | |
37 | warn "Warning, threads::shared has already been loaded. ". | |
38 | "To enable shared variables for these modules 'use threads' ". | |
39 | "must be called before any of those modules are loaded\n" | |
40 | if($threads::shared::threads_shared); | |
41 | } | |
42 | ||
43 | require Exporter; | |
44 | require DynaLoader; | |
45 | ||
46 | our @ISA = qw(Exporter DynaLoader); | |
47 | ||
48 | our %EXPORT_TAGS = ( all => [qw(yield)]); | |
49 | ||
50 | our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } ); | |
51 | ||
52 | our @EXPORT = qw( | |
53 | async | |
54 | ); | |
55 | our $VERSION = '0.99'; | |
56 | ||
57 | ||
58 | sub equal { | |
59 | return 1 if($_[0]->tid() == $_[1]->tid()); | |
60 | return 0; | |
61 | } | |
62 | ||
63 | sub async (&;@) { | |
64 | my $cref = shift; | |
65 | return threads->new($cref,@_); | |
66 | } | |
67 | ||
68 | sub object { | |
69 | return undef unless @_ > 1; | |
70 | foreach (threads->list) { | |
71 | return $_ if $_->tid == $_[1]; | |
72 | } | |
73 | return undef; | |
74 | } | |
75 | ||
76 | $threads::threads = 1; | |
77 | ||
78 | bootstrap threads $VERSION; | |
79 | ||
80 | # why document 'new' then use 'create' in the tests! | |
81 | *create = \&new; | |
82 | ||
83 | # Preloaded methods go here. | |
84 | ||
85 | 1; | |
86 | __END__ | |
87 | ||
88 | =head1 NAME | |
89 | ||
90 | threads - Perl extension allowing use of interpreter based threads from perl | |
91 | ||
92 | =head1 SYNOPSIS | |
93 | ||
94 | use threads; | |
95 | ||
96 | sub start_thread { | |
97 | print "Thread started\n"; | |
98 | } | |
99 | ||
100 | my $thread = threads->create("start_thread","argument"); | |
101 | my $thread2 = $thread->create(sub { print "I am a thread"},"argument"); | |
102 | my $thread3 = async { foreach (@files) { ... } }; | |
103 | ||
104 | $thread->join(); | |
105 | $thread->detach(); | |
106 | ||
107 | $thread = threads->self(); | |
108 | $thread = threads->object( $tid ); | |
109 | ||
110 | $thread->tid(); | |
111 | threads->tid(); | |
112 | threads->self->tid(); | |
113 | ||
114 | threads->yield(); | |
115 | ||
116 | threads->list(); | |
117 | ||
118 | =head1 DESCRIPTION | |
119 | ||
120 | Perl 5.6 introduced something called interpreter threads. Interpreter | |
121 | threads are different from "5005threads" (the thread model of Perl | |
122 | 5.005) by creating a new perl interpreter per thread and not sharing | |
123 | any data or state between threads by default. | |
124 | ||
125 | Prior to perl 5.8 this has only been available to people embedding | |
126 | perl and for emulating fork() on windows. | |
127 | ||
128 | The threads API is loosely based on the old Thread.pm API. It is very | |
129 | important to note that variables are not shared between threads, all | |
130 | variables are per default thread local. To use shared variables one | |
131 | must use threads::shared. | |
132 | ||
133 | It is also important to note that you must enable threads by doing | |
134 | C<use threads> as early as possible in the script itself and that it | |
135 | is not possible to enable threading inside an C<eval "">, C<do>, | |
136 | C<require>, or C<use>. In particular, if you are intending to share | |
137 | variables with threads::shared, you must C<use threads> before you | |
138 | C<use threads::shared> and C<threads> will emit a warning if you do | |
139 | it the other way around. | |
140 | ||
141 | =over | |
142 | ||
143 | =item $thread = threads->create(function, LIST) | |
144 | ||
145 | This will create a new thread with the entry point function and give | |
146 | it LIST as parameters. It will return the corresponding threads | |
147 | object. The new() method is an alias for create(). | |
148 | ||
149 | =item $thread->join | |
150 | ||
151 | This will wait for the corresponding thread to join. When the thread | |
152 | finishes, join() will return the return values of the entry point | |
153 | function. If the thread has been detached, an error will be thrown. | |
154 | If the program exits without all other threads having been either | |
155 | joined or detached, then a warning will be issued. (A program exits | |
156 | either because one of its threads explicitly calls exit(), or in the | |
157 | case of the main thread, reaches the end of the main program file.) | |
158 | ||
159 | =item $thread->detach | |
160 | ||
161 | Will make the thread unjoinable, and cause any eventual return value | |
162 | to be discarded. | |
163 | ||
164 | =item threads->self | |
165 | ||
166 | This will return the thread object for the current thread. | |
167 | ||
168 | =item $thread->tid | |
169 | ||
170 | This will return the id of the thread. Thread IDs are integers, with | |
171 | the main thread in a program being 0. Currently Perl assigns a unique | |
172 | tid to every thread ever created in your program, assigning the first | |
173 | thread to be created a tid of 1, and increasing the tid by 1 for each | |
174 | new thread that's created. | |
175 | ||
176 | NB the class method C<< threads->tid() >> is a quick way to get the | |
177 | current thread id if you don't have your thread object handy. | |
178 | ||
179 | =item threads->object( tid ) | |
180 | ||
181 | This will return the thread object for the thread associated with the | |
182 | specified tid. Returns undef if there is no thread associated with the tid | |
183 | or no tid is specified or the specified tid is undef. | |
184 | ||
185 | =item threads->yield(); | |
186 | ||
187 | This is a suggestion to the OS to let this thread yield CPU time to other | |
188 | threads. What actually happens is highly dependent upon the underlying | |
189 | thread implementation. | |
190 | ||
191 | You may do C<use threads qw(yield)> then use just a bare C<yield> in your | |
192 | code. | |
193 | ||
194 | =item threads->list(); | |
195 | ||
196 | This will return a list of all non joined, non detached threads. | |
197 | ||
198 | =item async BLOCK; | |
199 | ||
200 | C<async> creates a thread to execute the block immediately following | |
201 | it. This block is treated as an anonymous sub, and so must have a | |
202 | semi-colon after the closing brace. Like C<< threads->new >>, C<async> | |
203 | returns a thread object. | |
204 | ||
205 | =back | |
206 | ||
207 | =head1 WARNINGS | |
208 | ||
209 | =over 4 | |
210 | ||
211 | =item A thread exited while %d other threads were still running | |
212 | ||
213 | A thread (not necessarily the main thread) exited while there were | |
214 | still other threads running. Usually it's a good idea to first collect | |
215 | the return values of the created threads by joining them, and only then | |
216 | exit from the main thread. | |
217 | ||
218 | =back | |
219 | ||
220 | =head1 TODO | |
221 | ||
222 | The current implementation of threads has been an attempt to get | |
223 | a correct threading system working that could be built on, | |
224 | and optimized, in newer versions of perl. | |
225 | ||
226 | Currently the overhead of creating a thread is rather large, | |
227 | also the cost of returning values can be large. These are areas | |
228 | were there most likely will be work done to optimize what data | |
229 | that needs to be cloned. | |
230 | ||
231 | =head1 BUGS | |
232 | ||
233 | =over | |
234 | ||
235 | =item Parent-Child threads. | |
236 | ||
237 | On some platforms it might not be possible to destroy "parent" | |
238 | threads while there are still existing child "threads". | |
239 | ||
240 | This will possibly be fixed in later versions of perl. | |
241 | ||
242 | =item tid is I32 | |
243 | ||
244 | The thread id is a 32 bit integer, it can potentially overflow. | |
245 | This might be fixed in a later version of perl. | |
246 | ||
247 | =item Returning objects | |
248 | ||
249 | When you return an object the entire stash that the object is blessed | |
250 | as well. This will lead to a large memory usage. The ideal situation | |
251 | would be to detect the original stash if it existed. | |
252 | ||
253 | =item Creating threads inside BEGIN blocks | |
254 | ||
255 | Creating threads inside BEGIN blocks (or during the compilation phase | |
256 | in general) does not work. (In Windows, trying to use fork() inside | |
257 | BEGIN blocks is an equally losing proposition, since it has been | |
258 | implemented in very much the same way as threads.) | |
259 | ||
260 | =item PERL_OLD_SIGNALS are not threadsafe, will not be. | |
261 | ||
262 | If your Perl has been built with PERL_OLD_SIGNALS (one has | |
263 | to explicitly add that symbol to ccflags, see C<perl -V>), | |
264 | signal handling is not threadsafe. | |
265 | ||
266 | =back | |
267 | ||
268 | =head1 AUTHOR and COPYRIGHT | |
269 | ||
270 | Arthur Bergman E<lt>arthur at contiller.seE<gt> | |
271 | ||
272 | threads is released under the same license as Perl. | |
273 | ||
274 | Thanks to | |
275 | ||
276 | Richard Soderberg E<lt>rs at crystalflame.netE<gt> | |
277 | Helping me out tons, trying to find reasons for races and other weird bugs! | |
278 | ||
279 | Simon Cozens E<lt>simon at brecon.co.ukE<gt> | |
280 | Being there to answer zillions of annoying questions | |
281 | ||
282 | Rocco Caputo E<lt>troc at netrus.netE<gt> | |
283 | ||
284 | Vipul Ved Prakash E<lt>mail at vipul.netE<gt> | |
285 | Helping with debugging. | |
286 | ||
287 | please join perl-ithreads@perl.org for more information | |
288 | ||
289 | =head1 SEE ALSO | |
290 | ||
291 | L<threads::shared>, L<perlthrtut>, | |
292 | L<http://www.perl.com/pub/a/2002/06/11/threads.html>, | |
293 | L<perlcall>, L<perlembed>, L<perlguts> | |
294 | ||
295 | =cut |