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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 $caller[2]: | |
13 | ||
14 | This Perl hasn't been configured and built properly for the threads | |
15 | module to work. (The 'useithreads' configuration option hasn't been used.) | |
16 | ||
17 | Having threads support requires all of Perl and all of the XS modules in | |
18 | the Perl installation to be rebuilt, it is not just a question of adding | |
19 | the threads module. (In other words, threaded and non-threaded Perls | |
20 | are binary incompatible.) | |
21 | ||
22 | If you want to the use the threads module, please contact the people | |
23 | who built your Perl. | |
24 | ||
25 | Cannot continue, aborting. | |
26 | EOF | |
27 | } | |
28 | } | |
29 | ||
30 | use overload | |
31 | '==' => \&equal, | |
32 | 'fallback' => 1; | |
33 | ||
34 | BEGIN { | |
35 | warn "Warning, threads::shared has already been loaded. ". | |
36 | "To enable shared variables for these modules 'use threads' ". | |
37 | "must be called before any of those modules are loaded\n" | |
38 | if($threads::shared::threads_shared); | |
39 | } | |
40 | ||
41 | require Exporter; | |
42 | require DynaLoader; | |
43 | ||
44 | our @ISA = qw(Exporter DynaLoader); | |
45 | ||
46 | our %EXPORT_TAGS = ( all => [qw(yield)]); | |
47 | ||
48 | our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } ); | |
49 | ||
50 | our @EXPORT = qw( | |
51 | async | |
52 | ); | |
53 | our $VERSION = '1.07'; | |
54 | ||
55 | ||
56 | # || 0 to ensure compatibility with previous versions | |
57 | sub equal { ($_[0]->tid == $_[1]->tid) || 0 } | |
58 | ||
59 | # use "goto" trick to avoid pad problems from 5.8.1 (fixed in 5.8.2) | |
60 | # should also be faster | |
61 | sub async (&;@) { unshift @_,'threads'; goto &new } | |
62 | ||
63 | sub object { | |
64 | return undef unless @_ > 1; | |
65 | foreach (threads->list) { | |
66 | return $_ if $_->tid == $_[1]; | |
67 | } | |
68 | return undef; | |
69 | } | |
70 | ||
71 | $threads::threads = 1; | |
72 | ||
73 | bootstrap threads $VERSION; | |
74 | ||
75 | # why document 'new' then use 'create' in the tests! | |
76 | *create = \&new; | |
77 | ||
78 | # Preloaded methods go here. | |
79 | ||
80 | 1; | |
81 | __END__ | |
82 | ||
83 | =head1 NAME | |
84 | ||
85 | threads - Perl extension allowing use of interpreter based threads from perl | |
86 | ||
87 | =head1 SYNOPSIS | |
88 | ||
89 | use threads; | |
90 | ||
91 | sub start_thread { | |
92 | print "Thread started\n"; | |
93 | } | |
94 | ||
95 | my $thread = threads->create("start_thread","argument"); | |
96 | my $thread2 = $thread->create(sub { print "I am a thread"},"argument"); | |
97 | my $thread3 = async { foreach (@files) { ... } }; | |
98 | ||
99 | $thread->join(); | |
100 | $thread->detach(); | |
101 | ||
102 | $thread = threads->self(); | |
103 | $thread = threads->object( $tid ); | |
104 | ||
105 | $thread->tid(); | |
106 | threads->tid(); | |
107 | threads->self->tid(); | |
108 | ||
109 | threads->yield(); | |
110 | ||
111 | threads->list(); | |
112 | ||
113 | =head1 DESCRIPTION | |
114 | ||
115 | Perl 5.6 introduced something called interpreter threads. Interpreter | |
116 | threads are different from "5005threads" (the thread model of Perl | |
117 | 5.005) by creating a new perl interpreter per thread and not sharing | |
118 | any data or state between threads by default. | |
119 | ||
120 | Prior to perl 5.8 this has only been available to people embedding | |
121 | perl and for emulating fork() on windows. | |
122 | ||
123 | The threads API is loosely based on the old Thread.pm API. It is very | |
124 | important to note that variables are not shared between threads, all | |
125 | variables are per default thread local. To use shared variables one | |
126 | must use threads::shared. | |
127 | ||
128 | It is also important to note that you must enable threads by doing | |
129 | C<use threads> as early as possible in the script itself and that it | |
130 | is not possible to enable threading inside an C<eval "">, C<do>, | |
131 | C<require>, or C<use>. In particular, if you are intending to share | |
132 | variables with threads::shared, you must C<use threads> before you | |
133 | C<use threads::shared> and C<threads> will emit a warning if you do | |
134 | it the other way around. | |
135 | ||
136 | =over | |
137 | ||
138 | =item $thread = threads->create(function, LIST) | |
139 | ||
140 | This will create a new thread with the entry point function and give | |
141 | it LIST as parameters. It will return the corresponding threads | |
142 | object, or C<undef> if thread creation failed. The new() method is an | |
143 | alias for create(). | |
144 | ||
145 | =item $thread->join | |
146 | ||
147 | This will wait for the corresponding thread to join. When the thread | |
148 | finishes, join() will return the return values of the entry point | |
149 | function. If the thread has been detached, an error will be thrown. | |
150 | ||
151 | The context (void, scalar or list) of the thread creation is also the | |
152 | context for join(). This means that if you intend to return an array | |
153 | from a thread, you must use C<my ($thread) = threads->new(...)>, and | |
154 | that if you intend to return a scalar, you must use C<my $thread = ...>. | |
155 | ||
156 | If the program exits without all other threads having been either | |
157 | joined or detached, then a warning will be issued. (A program exits | |
158 | either because one of its threads explicitly calls exit(), or in the | |
159 | case of the main thread, reaches the end of the main program file.) | |
160 | ||
161 | ||
162 | =item $thread->detach | |
163 | ||
164 | Will make the thread unjoinable, and cause any eventual return value | |
165 | to be discarded. | |
166 | ||
167 | =item threads->self | |
168 | ||
169 | This will return the thread object for the current thread. | |
170 | ||
171 | =item $thread->tid | |
172 | ||
173 | This will return the id of the thread. Thread IDs are integers, with | |
174 | the main thread in a program being 0. Currently Perl assigns a unique | |
175 | tid to every thread ever created in your program, assigning the first | |
176 | thread to be created a tid of 1, and increasing the tid by 1 for each | |
177 | new thread that's created. | |
178 | ||
179 | NB the class method C<< threads->tid() >> is a quick way to get the | |
180 | current thread id if you don't have your thread object handy. | |
181 | ||
182 | =item threads->object( tid ) | |
183 | ||
184 | This will return the thread object for the thread associated with the | |
185 | specified tid. Returns undef if there is no thread associated with the tid | |
186 | or no tid is specified or the specified tid is undef. | |
187 | ||
188 | =item threads->yield(); | |
189 | ||
190 | This is a suggestion to the OS to let this thread yield CPU time to other | |
191 | threads. What actually happens is highly dependent upon the underlying | |
192 | thread implementation. | |
193 | ||
194 | You may do C<use threads qw(yield)> then use just a bare C<yield> in your | |
195 | code. | |
196 | ||
197 | =item threads->list(); | |
198 | ||
199 | This will return a list of all non joined, non detached threads. | |
200 | ||
201 | =item async BLOCK; | |
202 | ||
203 | C<async> creates a thread to execute the block immediately following | |
204 | it. This block is treated as an anonymous sub, and so must have a | |
205 | semi-colon after the closing brace. Like C<< threads->new >>, C<async> | |
206 | returns a thread object. | |
207 | ||
208 | =back | |
209 | ||
210 | =head1 WARNINGS | |
211 | ||
212 | =over 4 | |
213 | ||
214 | =item A thread exited while %d other threads were still running | |
215 | ||
216 | A thread (not necessarily the main thread) exited while there were | |
217 | still other threads running. Usually it's a good idea to first collect | |
218 | the return values of the created threads by joining them, and only then | |
219 | exit from the main thread. | |
220 | ||
221 | =back | |
222 | ||
223 | =head1 TODO | |
224 | ||
225 | The current implementation of threads has been an attempt to get | |
226 | a correct threading system working that could be built on, | |
227 | and optimized, in newer versions of perl. | |
228 | ||
229 | Currently the overhead of creating a thread is rather large, | |
230 | also the cost of returning values can be large. These are areas | |
231 | were there most likely will be work done to optimize what data | |
232 | that needs to be cloned. | |
233 | ||
234 | =head1 BUGS | |
235 | ||
236 | =over | |
237 | ||
238 | =item Parent-Child threads. | |
239 | ||
240 | On some platforms it might not be possible to destroy "parent" | |
241 | threads while there are still existing child "threads". | |
242 | ||
243 | This will possibly be fixed in later versions of perl. | |
244 | ||
245 | =item tid is I32 | |
246 | ||
247 | The thread id is a 32 bit integer, it can potentially overflow. | |
248 | This might be fixed in a later version of perl. | |
249 | ||
250 | =item Returning objects | |
251 | ||
252 | When you return an object the entire stash that the object is blessed | |
253 | as well. This will lead to a large memory usage. The ideal situation | |
254 | would be to detect the original stash if it existed. | |
255 | ||
256 | =item Creating threads inside BEGIN blocks | |
257 | ||
258 | Creating threads inside BEGIN blocks (or during the compilation phase | |
259 | in general) does not work. (In Windows, trying to use fork() inside | |
260 | BEGIN blocks is an equally losing proposition, since it has been | |
261 | implemented in very much the same way as threads.) | |
262 | ||
263 | =item PERL_OLD_SIGNALS are not threadsafe, will not be. | |
264 | ||
265 | If your Perl has been built with PERL_OLD_SIGNALS (one has | |
266 | to explicitly add that symbol to ccflags, see C<perl -V>), | |
267 | signal handling is not threadsafe. | |
268 | ||
269 | =back | |
270 | ||
271 | =head1 AUTHOR and COPYRIGHT | |
272 | ||
273 | Arthur Bergman E<lt>sky at nanisky.comE<gt> | |
274 | ||
275 | threads is released under the same license as Perl. | |
276 | ||
277 | Thanks to | |
278 | ||
279 | Richard Soderberg E<lt>perl at crystalflame.netE<gt> | |
280 | Helping me out tons, trying to find reasons for races and other weird bugs! | |
281 | ||
282 | Simon Cozens E<lt>simon at brecon.co.ukE<gt> | |
283 | Being there to answer zillions of annoying questions | |
284 | ||
285 | Rocco Caputo E<lt>troc at netrus.netE<gt> | |
286 | ||
287 | Vipul Ved Prakash E<lt>mail at vipul.netE<gt> | |
288 | Helping with debugging. | |
289 | ||
290 | please join perl-ithreads@perl.org for more information | |
291 | ||
292 | =head1 SEE ALSO | |
293 | ||
294 | L<threads::shared>, L<perlthrtut>, | |
295 | L<http://www.perl.com/pub/a/2002/06/11/threads.html>, | |
296 | L<perlcall>, L<perlembed>, L<perlguts> | |
297 | ||
298 | =cut |