| 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 |