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47ba8780 AB |
1 | package threads; |
2 | ||
32419a4c | 3 | use 5.008; |
47ba8780 AB |
4 | use strict; |
5 | use warnings; | |
73e09c8f JH |
6 | use Config; |
7 | ||
8 | BEGIN { | |
9 | unless ($Config{useithreads}) { | |
10 | my @caller = caller(2); | |
11 | die <<EOF; | |
12 | $caller[1] line $caller[2]: | |
13 | ||
14 | This Perl hasn't been configured and built properly for the threads | |
15 | module to work. (The 'useithreads' configuration option hasn't been used.) | |
16 | ||
5e549d84 | 17 | Having threads support requires all of Perl and all of the XS modules in |
73e09c8f JH |
18 | the Perl installation to be rebuilt, it is not just a question of adding |
19 | the threads module. (In other words, threaded and non-threaded Perls | |
20 | are binary incompatible.) | |
21 | ||
22 | If you want to the use the threads module, please contact the people | |
23 | who built your Perl. | |
24 | ||
25 | Cannot continue, aborting. | |
26 | EOF | |
27 | } | |
28 | } | |
47ba8780 | 29 | |
68795e93 | 30 | use overload |
43d3ddbe | 31 | '==' => \&equal, |
47ba8780 AB |
32 | 'fallback' => 1; |
33 | ||
47ba8780 AB |
34 | #use threads::Shared; |
35 | ||
dab065ea AB |
36 | BEGIN { |
37 | warn "Warning, threads::shared has already been loaded. ". | |
38 | "To enable shared variables for these modules 'use threads' ". | |
39 | "must be called before any of those modules are loaded\n" | |
40 | if($threads::shared::threads_shared); | |
41 | } | |
42 | ||
47ba8780 AB |
43 | require Exporter; |
44 | require DynaLoader; | |
45 | ||
47ba8780 AB |
46 | our @ISA = qw(Exporter DynaLoader); |
47 | ||
70f2e746 | 48 | our %EXPORT_TAGS = ( all => [qw(yield)]); |
47ba8780 AB |
49 | |
50 | our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } ); | |
51 | ||
52 | our @EXPORT = qw( | |
dcb6ccbc | 53 | async |
47ba8780 | 54 | ); |
4522225b | 55 | our $VERSION = '1.00'; |
47ba8780 | 56 | |
47ba8780 | 57 | |
43d3ddbe | 58 | sub equal { |
47ba8780 AB |
59 | return 1 if($_[0]->tid() == $_[1]->tid()); |
60 | return 0; | |
61 | } | |
62 | ||
dcb6ccbc AB |
63 | sub async (&;@) { |
64 | my $cref = shift; | |
65 | return threads->new($cref,@_); | |
66 | } | |
67 | ||
8c9849ff EM |
68 | sub object { |
69 | return undef unless @_ > 1; | |
70 | foreach (threads->list) { | |
71 | return $_ if $_->tid == $_[1]; | |
72 | } | |
73 | return undef; | |
74 | } | |
75 | ||
8222d950 | 76 | $threads::threads = 1; |
47ba8780 AB |
77 | |
78 | bootstrap threads $VERSION; | |
79 | ||
68795e93 NIS |
80 | # why document 'new' then use 'create' in the tests! |
81 | *create = \&new; | |
82 | ||
47ba8780 AB |
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 | ||
38875929 | 94 | use threads; |
47ba8780 | 95 | |
38875929 DM |
96 | sub start_thread { |
97 | print "Thread started\n"; | |
98 | } | |
47ba8780 | 99 | |
38875929 DM |
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) { ... } }; | |
47ba8780 | 103 | |
38875929 DM |
104 | $thread->join(); |
105 | $thread->detach(); | |
47ba8780 | 106 | |
38875929 | 107 | $thread = threads->self(); |
8c9849ff | 108 | $thread = threads->object( $tid ); |
11c51ed3 | 109 | |
38875929 DM |
110 | $thread->tid(); |
111 | threads->tid(); | |
112 | threads->self->tid(); | |
47ba8780 | 113 | |
38875929 | 114 | threads->yield(); |
f9dff5f5 | 115 | |
38875929 | 116 | threads->list(); |
678a9b6c | 117 | |
47ba8780 AB |
118 | =head1 DESCRIPTION |
119 | ||
43d3ddbe JH |
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 | |
32419a4c | 123 | any data or state between threads by default. |
11c51ed3 | 124 | |
43d3ddbe JH |
125 | Prior to perl 5.8 this has only been available to people embedding |
126 | perl and for emulating fork() on windows. | |
11c51ed3 | 127 | |
43d3ddbe JH |
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. | |
11c51ed3 | 132 | |
6bc4bdd0 JH |
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. | |
47ba8780 AB |
140 | |
141 | =over | |
142 | ||
9c4972d9 | 143 | =item $thread = threads->create(function, LIST) |
47ba8780 | 144 | |
ad91d581 JH |
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 | |
38875929 | 147 | object. The new() method is an alias for create(). |
47ba8780 | 148 | |
11c51ed3 | 149 | =item $thread->join |
47ba8780 | 150 | |
32419a4c JH |
151 | This will wait for the corresponding thread to join. When the thread |
152 | finishes, join() will return the return values of the entry point | |
153 | function. If the thread has been detached, an error will be thrown. | |
93512b4d JH |
154 | |
155 | The context (scalar or list) of the thread creation is also the | |
156 | context for join(). This means that if you intend to return an array | |
157 | from a thread, you must use C<my ($thread) = threads->new(...)>, and | |
158 | that if you intend to return a scalar, you must use C<my $thread = ...>. | |
159 | ||
32419a4c JH |
160 | If the program exits without all other threads having been either |
161 | joined or detached, then a warning will be issued. (A program exits | |
162 | either because one of its threads explicitly calls exit(), or in the | |
163 | case of the main thread, reaches the end of the main program file.) | |
47ba8780 | 164 | |
93512b4d | 165 | |
11c51ed3 | 166 | =item $thread->detach |
47ba8780 | 167 | |
32419a4c JH |
168 | Will make the thread unjoinable, and cause any eventual return value |
169 | to be discarded. | |
47ba8780 AB |
170 | |
171 | =item threads->self | |
172 | ||
38875929 | 173 | This will return the thread object for the current thread. |
47ba8780 | 174 | |
11c51ed3 | 175 | =item $thread->tid |
47ba8780 | 176 | |
32419a4c JH |
177 | This will return the id of the thread. Thread IDs are integers, with |
178 | the main thread in a program being 0. Currently Perl assigns a unique | |
179 | tid to every thread ever created in your program, assigning the first | |
180 | thread to be created a tid of 1, and increasing the tid by 1 for each | |
181 | new thread that's created. | |
38875929 DM |
182 | |
183 | NB the class method C<< threads->tid() >> is a quick way to get the | |
184 | current thread id if you don't have your thread object handy. | |
47ba8780 | 185 | |
8c9849ff EM |
186 | =item threads->object( tid ) |
187 | ||
188 | This will return the thread object for the thread associated with the | |
189 | specified tid. Returns undef if there is no thread associated with the tid | |
190 | or no tid is specified or the specified tid is undef. | |
191 | ||
f9dff5f5 AB |
192 | =item threads->yield(); |
193 | ||
38875929 DM |
194 | This is a suggestion to the OS to let this thread yield CPU time to other |
195 | threads. What actually happens is highly dependent upon the underlying | |
196 | thread implementation. | |
f9dff5f5 | 197 | |
70f2e746 DM |
198 | You may do C<use threads qw(yield)> then use just a bare C<yield> in your |
199 | code. | |
200 | ||
678a9b6c AB |
201 | =item threads->list(); |
202 | ||
203 | This will return a list of all non joined, non detached threads. | |
204 | ||
386c44e5 AB |
205 | =item async BLOCK; |
206 | ||
207 | C<async> creates a thread to execute the block immediately following | |
208 | it. This block is treated as an anonymous sub, and so must have a | |
38875929 | 209 | semi-colon after the closing brace. Like C<< threads->new >>, C<async> |
386c44e5 AB |
210 | returns a thread object. |
211 | ||
47ba8780 AB |
212 | =back |
213 | ||
e4f9f4fe JH |
214 | =head1 WARNINGS |
215 | ||
216 | =over 4 | |
217 | ||
c133c03f | 218 | =item A thread exited while %d other threads were still running |
e4f9f4fe | 219 | |
c133c03f JH |
220 | A thread (not necessarily the main thread) exited while there were |
221 | still other threads running. Usually it's a good idea to first collect | |
222 | the return values of the created threads by joining them, and only then | |
32419a4c | 223 | exit from the main thread. |
e4f9f4fe JH |
224 | |
225 | =back | |
47ba8780 | 226 | |
ab80e3f2 | 227 | =head1 TODO |
678a9b6c | 228 | |
38875929 | 229 | The current implementation of threads has been an attempt to get |
678a9b6c AB |
230 | a correct threading system working that could be built on, |
231 | and optimized, in newer versions of perl. | |
232 | ||
38875929 | 233 | Currently the overhead of creating a thread is rather large, |
678a9b6c AB |
234 | also the cost of returning values can be large. These are areas |
235 | were there most likely will be work done to optimize what data | |
236 | that needs to be cloned. | |
47ba8780 | 237 | |
ab80e3f2 EM |
238 | =head1 BUGS |
239 | ||
47ba8780 AB |
240 | =over |
241 | ||
678a9b6c AB |
242 | =item Parent-Child threads. |
243 | ||
244 | On some platforms it might not be possible to destroy "parent" | |
245 | threads while there are still existing child "threads". | |
246 | ||
ab80e3f2 EM |
247 | This will possibly be fixed in later versions of perl. |
248 | ||
678a9b6c AB |
249 | =item tid is I32 |
250 | ||
32419a4c | 251 | The thread id is a 32 bit integer, it can potentially overflow. |
678a9b6c | 252 | This might be fixed in a later version of perl. |
47ba8780 | 253 | |
678a9b6c | 254 | =item Returning objects |
47ba8780 | 255 | |
678a9b6c | 256 | When you return an object the entire stash that the object is blessed |
32419a4c JH |
257 | as well. This will lead to a large memory usage. The ideal situation |
258 | would be to detect the original stash if it existed. | |
678a9b6c | 259 | |
88f8c1df JH |
260 | =item Creating threads inside BEGIN blocks |
261 | ||
262 | Creating threads inside BEGIN blocks (or during the compilation phase | |
263 | in general) does not work. (In Windows, trying to use fork() inside | |
264 | BEGIN blocks is an equally losing proposition, since it has been | |
265 | implemented in very much the same way as threads.) | |
266 | ||
678a9b6c | 267 | =item PERL_OLD_SIGNALS are not threadsafe, will not be. |
47ba8780 | 268 | |
88f8c1df JH |
269 | If your Perl has been built with PERL_OLD_SIGNALS (one has |
270 | to explicitly add that symbol to ccflags, see C<perl -V>), | |
271 | signal handling is not threadsafe. | |
272 | ||
47ba8780 AB |
273 | =back |
274 | ||
275 | =head1 AUTHOR and COPYRIGHT | |
276 | ||
11c51ed3 | 277 | Arthur Bergman E<lt>arthur at contiller.seE<gt> |
47ba8780 | 278 | |
43d3ddbe | 279 | threads is released under the same license as Perl. |
47ba8780 | 280 | |
68795e93 | 281 | Thanks to |
47ba8780 | 282 | |
ca9279ba | 283 | Richard Soderberg E<lt>perl at crystalflame.netE<gt> |
ad91d581 | 284 | Helping me out tons, trying to find reasons for races and other weird bugs! |
47ba8780 | 285 | |
ad91d581 JH |
286 | Simon Cozens E<lt>simon at brecon.co.ukE<gt> |
287 | Being there to answer zillions of annoying questions | |
47ba8780 | 288 | |
ad91d581 | 289 | Rocco Caputo E<lt>troc at netrus.netE<gt> |
47ba8780 | 290 | |
ad91d581 | 291 | Vipul Ved Prakash E<lt>mail at vipul.netE<gt> |
47ba8780 AB |
292 | Helping with debugging. |
293 | ||
294 | please join perl-ithreads@perl.org for more information | |
295 | ||
47ba8780 AB |
296 | =head1 SEE ALSO |
297 | ||
5e549d84 JH |
298 | L<threads::shared>, L<perlthrtut>, |
299 | L<http://www.perl.com/pub/a/2002/06/11/threads.html>, | |
300 | L<perlcall>, L<perlembed>, L<perlguts> | |
47ba8780 AB |
301 | |
302 | =cut |