1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - create and manage simple coroutines |
3 | Coro - coroutine process abstraction |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | $new = new Coro sub { |
9 | async { |
10 | print "in coroutine, switching back\n"; |
10 | # some asynchronous thread of execution |
11 | $new->transfer($main); |
|
|
12 | print "in coroutine again, switching back\n"; |
|
|
13 | $new->transfer($main); |
|
|
14 | }; |
11 | }; |
15 | |
12 | |
16 | $main = new Coro; |
13 | # alternatively create an async process like this: |
17 | |
14 | |
18 | print "in main, switching to coroutine\n"; |
15 | sub some_func : Coro { |
19 | $main->transfer($new); |
16 | # some more async code |
20 | print "back in main, switch to coroutine again\n"; |
17 | } |
21 | $main->transfer($new); |
18 | |
22 | print "back in main\n"; |
19 | cede; |
23 | |
20 | |
24 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
25 | |
22 | |
26 | This module implements coroutines. Coroutines, similar to continuations, |
23 | This module collection manages coroutines. Coroutines are similar to |
27 | allow you to run more than one "thread of execution" in parallel. Unlike |
24 | Threads but don't run in parallel. |
28 | threads this, only voluntary switching is used so locking problems are |
|
|
29 | greatly reduced. |
|
|
30 | |
25 | |
31 | Although this is the "main" module of the Coro family it provides only |
26 | This module is still experimental, see the BUGS section below. |
32 | low-level functionality. See L<Coro::Process> and related modules for a |
27 | |
33 | more useful process abstraction including scheduling. |
28 | In this module, coroutines are defined as "callchain + lexical variables |
|
|
29 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
|
|
30 | callchain, it's own set of lexicals and it's own set of perl's most |
|
|
31 | important global variables. |
|
|
32 | |
|
|
33 | =cut |
|
|
34 | |
|
|
35 | package Coro; |
|
|
36 | |
|
|
37 | use Coro::State; |
|
|
38 | |
|
|
39 | use base Exporter; |
|
|
40 | |
|
|
41 | $VERSION = 0.12; |
|
|
42 | |
|
|
43 | @EXPORT = qw(async cede schedule terminate current); |
|
|
44 | @EXPORT_OK = qw($current); |
|
|
45 | |
|
|
46 | { |
|
|
47 | my @async; |
|
|
48 | |
|
|
49 | # this way of handling attributes simply is NOT scalable ;() |
|
|
50 | sub import { |
|
|
51 | Coro->export_to_level(1, @_); |
|
|
52 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
|
|
53 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
|
|
54 | my ($package, $ref) = (shift, shift); |
|
|
55 | my @attrs; |
|
|
56 | for (@_) { |
|
|
57 | if ($_ eq "Coro") { |
|
|
58 | push @async, $ref; |
|
|
59 | } else { |
|
|
60 | push @attrs, $_; |
|
|
61 | } |
|
|
62 | } |
|
|
63 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
|
|
64 | }; |
|
|
65 | } |
|
|
66 | |
|
|
67 | sub INIT { |
|
|
68 | &async(pop @async) while @async; |
|
|
69 | } |
|
|
70 | } |
|
|
71 | |
|
|
72 | =item $main |
|
|
73 | |
|
|
74 | This coroutine represents the main program. |
|
|
75 | |
|
|
76 | =cut |
|
|
77 | |
|
|
78 | our $main = new Coro; |
|
|
79 | |
|
|
80 | =item $current (or as function: current) |
|
|
81 | |
|
|
82 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
|
|
83 | |
|
|
84 | =cut |
|
|
85 | |
|
|
86 | # maybe some other module used Coro::Specific before... |
|
|
87 | if ($current) { |
|
|
88 | $main->{specific} = $current->{specific}; |
|
|
89 | } |
|
|
90 | |
|
|
91 | our $current = $main; |
|
|
92 | |
|
|
93 | sub current() { $current } |
|
|
94 | |
|
|
95 | =item $idle |
|
|
96 | |
|
|
97 | The coroutine to switch to when no other coroutine is running. The default |
|
|
98 | implementation prints "FATAL: deadlock detected" and exits. |
|
|
99 | |
|
|
100 | =cut |
|
|
101 | |
|
|
102 | # should be done using priorities :( |
|
|
103 | our $idle = new Coro sub { |
|
|
104 | print STDERR "FATAL: deadlock detected\n"; |
|
|
105 | exit(51); |
|
|
106 | }; |
|
|
107 | |
|
|
108 | # this coroutine is necessary because a coroutine |
|
|
109 | # cannot destroy itself. |
|
|
110 | my @destroy; |
|
|
111 | my $manager = new Coro sub { |
|
|
112 | while() { |
|
|
113 | delete ((pop @destroy)->{_coro_state}) while @destroy; |
|
|
114 | &schedule; |
|
|
115 | } |
|
|
116 | }; |
|
|
117 | |
|
|
118 | # we really need priorities... |
|
|
119 | my @ready; # the ready queue. hehe, rather broken ;) |
|
|
120 | |
|
|
121 | # static methods. not really. |
|
|
122 | |
|
|
123 | =head2 STATIC METHODS |
|
|
124 | |
|
|
125 | Static methods are actually functions that operate on the current process only. |
34 | |
126 | |
35 | =over 4 |
127 | =over 4 |
36 | |
128 | |
37 | =cut |
129 | =item async { ... } [@args...] |
38 | |
130 | |
39 | package Coro; |
131 | Create a new asynchronous process and return it's process object |
|
|
132 | (usually unused). When the sub returns the new process is automatically |
|
|
133 | terminated. |
40 | |
134 | |
41 | BEGIN { |
135 | # create a new coroutine that just prints its arguments |
42 | $VERSION = 0.03; |
136 | async { |
|
|
137 | print "@_\n"; |
|
|
138 | } 1,2,3,4; |
43 | |
139 | |
44 | require XSLoader; |
140 | The coderef you submit MUST NOT be a closure that refers to variables |
45 | XSLoader::load Coro, $VERSION; |
141 | in an outer scope. This does NOT work. Pass arguments into it instead. |
46 | } |
|
|
47 | |
142 | |
48 | =item $coro = new [$coderef [, @args]] |
|
|
49 | |
|
|
50 | Create a new coroutine and return it. The first C<transfer> call to this |
|
|
51 | coroutine will start execution at the given coderef. If, the subroutine |
|
|
52 | returns it will be executed again. |
|
|
53 | |
|
|
54 | If the coderef is omitted this function will create a new "empty" |
|
|
55 | coroutine, i.e. a coroutine that cannot be transfered to but can be used |
|
|
56 | to save the current coroutine in. |
|
|
57 | |
|
|
58 | =cut |
143 | =cut |
|
|
144 | |
|
|
145 | sub async(&@) { |
|
|
146 | my $pid = new Coro @_; |
|
|
147 | $manager->ready; # this ensures that the stack is cloned from the manager |
|
|
148 | $pid->ready; |
|
|
149 | $pid; |
|
|
150 | } |
|
|
151 | |
|
|
152 | =item schedule |
|
|
153 | |
|
|
154 | Calls the scheduler. Please note that the current process will not be put |
|
|
155 | into the ready queue, so calling this function usually means you will |
|
|
156 | never be called again. |
|
|
157 | |
|
|
158 | =cut |
|
|
159 | |
|
|
160 | my $prev; |
|
|
161 | |
|
|
162 | sub schedule { |
|
|
163 | # should be done using priorities :( |
|
|
164 | ($prev, $current) = ($current, shift @ready || $idle); |
|
|
165 | Coro::State::transfer($prev, $current); |
|
|
166 | } |
|
|
167 | |
|
|
168 | =item cede |
|
|
169 | |
|
|
170 | "Cede" to other processes. This function puts the current process into the |
|
|
171 | ready queue and calls C<schedule>, which has the effect of giving up the |
|
|
172 | current "timeslice" to other coroutines of the same or higher priority. |
|
|
173 | |
|
|
174 | =cut |
|
|
175 | |
|
|
176 | sub cede { |
|
|
177 | $current->ready; |
|
|
178 | &schedule; |
|
|
179 | } |
|
|
180 | |
|
|
181 | =item terminate |
|
|
182 | |
|
|
183 | Terminates the current process. |
|
|
184 | |
|
|
185 | Future versions of this function will allow result arguments. |
|
|
186 | |
|
|
187 | =cut |
|
|
188 | |
|
|
189 | sub terminate { |
|
|
190 | push @destroy, $current; |
|
|
191 | $manager->ready; |
|
|
192 | &schedule; |
|
|
193 | # NORETURN |
|
|
194 | } |
|
|
195 | |
|
|
196 | =back |
|
|
197 | |
|
|
198 | # dynamic methods |
|
|
199 | |
|
|
200 | =head2 PROCESS METHODS |
|
|
201 | |
|
|
202 | These are the methods you can call on process objects. |
|
|
203 | |
|
|
204 | =over 4 |
|
|
205 | |
|
|
206 | =item new Coro \&sub [, @args...] |
|
|
207 | |
|
|
208 | Create a new process and return it. When the sub returns the process |
|
|
209 | automatically terminates. To start the process you must first put it into |
|
|
210 | the ready queue by calling the ready method. |
|
|
211 | |
|
|
212 | The coderef you submit MUST NOT be a closure that refers to variables |
|
|
213 | in an outer scope. This does NOT work. Pass arguments into it instead. |
|
|
214 | |
|
|
215 | =cut |
|
|
216 | |
|
|
217 | sub _newcoro { |
|
|
218 | terminate &{+shift}; |
|
|
219 | } |
59 | |
220 | |
60 | sub new { |
221 | sub new { |
61 | my $class = $_[0]; |
222 | my $class = shift; |
62 | my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; |
223 | bless { |
63 | bless _newprocess { |
224 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
64 | do { |
|
|
65 | eval { &$proc }; |
|
|
66 | if ($@) { |
|
|
67 | $error_msg = $@; |
|
|
68 | $error_coro = _newprocess { }; |
|
|
69 | &transfer($error_coro, $error); |
|
|
70 | } |
|
|
71 | } while (1); |
|
|
72 | }, $class; |
225 | }, $class; |
73 | } |
226 | } |
74 | |
227 | |
75 | =item $prev->transfer($next) |
228 | =item $process->ready |
76 | |
229 | |
77 | Save the state of the current subroutine in C<$prev> and switch to the |
230 | Put the current process into the ready queue. |
78 | coroutine saved in C<$next>. |
|
|
79 | |
231 | |
80 | The "state" of a subroutine only ever includes scope, i.e. lexical |
|
|
81 | variables and the current execution state. It does not save/restore any |
|
|
82 | global variables such as C<$_> or C<$@> or any other special or non |
|
|
83 | special variables. So remember that every function call that might call |
|
|
84 | C<transfer> (such as C<Coro::Channel::put>) might clobber any global |
|
|
85 | and/or special variables. Yes, this is by design ;) You cna always create |
|
|
86 | your own process abstraction model that saves these variables. |
|
|
87 | |
|
|
88 | The easiest way to do this is to create your own scheduling primitive like this: |
|
|
89 | |
|
|
90 | sub schedule { |
|
|
91 | local ($_, $@, ...); |
|
|
92 | $old->transfer($new); |
|
|
93 | } |
|
|
94 | |
|
|
95 | =cut |
232 | =cut |
96 | |
233 | |
97 | # I call the _transfer function from a perl function |
234 | sub ready { |
98 | # because that way perl saves all important things on |
235 | push @ready, $_[0]; |
99 | # the stack. Actually, I'd do it from within XS, but |
|
|
100 | # I couldn't get it to work. |
|
|
101 | sub transfer { |
|
|
102 | _transfer($_[0], $_[1]); |
|
|
103 | } |
236 | } |
104 | |
237 | |
105 | =item $error, $error_msg, $error_coro |
238 | =back |
106 | |
239 | |
107 | This coroutine will be called on fatal errors. C<$error_msg> and |
|
|
108 | C<$error_coro> return the error message and the error-causing coroutine |
|
|
109 | (NOT an object) respectively. This API might change. |
|
|
110 | |
|
|
111 | =cut |
240 | =cut |
112 | |
|
|
113 | $error_msg = |
|
|
114 | $error_coro = undef; |
|
|
115 | |
|
|
116 | $error = _newprocess { |
|
|
117 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
|
|
118 | exit 50; |
|
|
119 | }; |
|
|
120 | |
241 | |
121 | 1; |
242 | 1; |
122 | |
243 | |
123 | =back |
244 | =head1 BUGS/LIMITATIONS |
124 | |
245 | |
125 | =head1 BUGS |
246 | - could be faster, especially when the core would introduce special |
126 | |
247 | support for coroutines (like it does for threads). |
127 | This module has not yet been extensively tested. |
248 | - there is still a memleak on coroutine termination that I could not |
|
|
249 | identify. Could be as small as a single SV. |
|
|
250 | - this module is not well-tested. |
|
|
251 | - if variables or arguments "disappear" (become undef) or become |
|
|
252 | corrupted please contact the author so he cen iron out the |
|
|
253 | remaining bugs. |
|
|
254 | - this module is not thread-safe. You must only ever use this module from |
|
|
255 | the same thread (this requirement might be loosened in the future to |
|
|
256 | allow per-thread schedulers, but Coro::State does not yet allow this). |
128 | |
257 | |
129 | =head1 SEE ALSO |
258 | =head1 SEE ALSO |
130 | |
259 | |
131 | L<Coro::Process>, L<Coro::Signal>. |
260 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
|
|
261 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
|
|
262 | L<Coro::L<Coro::Handle>, L<Coro::Socket>. |
132 | |
263 | |
133 | =head1 AUTHOR |
264 | =head1 AUTHOR |
134 | |
265 | |
135 | Marc Lehmann <pcg@goof.com> |
266 | Marc Lehmann <pcg@goof.com> |
136 | http://www.goof.com/pcg/marc/ |
267 | http://www.goof.com/pcg/marc/ |