1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - create an manage coroutines |
3 | Coro - create and manage simple coroutines |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
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9 | $new = new Coro sub { |
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10 | print "in coroutine, switching back\n"; |
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11 | $new->transfer($main); |
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12 | print "in coroutine again, switching back\n"; |
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13 | $new->transfer($main); |
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14 | }; |
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15 | |
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16 | $main = new Coro; |
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17 | |
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18 | print "in main, switching to coroutine\n"; |
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19 | $main->transfer($new); |
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20 | print "back in main, switch to coroutine again\n"; |
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21 | $main->transfer($new); |
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22 | print "back in main\n"; |
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23 | |
9 | =head1 DESCRIPTION |
24 | =head1 DESCRIPTION |
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25 | |
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26 | This module implements coroutines. Coroutines, similar to continuations, |
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27 | allow you to run more than one "thread of execution" in parallel. Unlike |
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28 | threads this, only voluntary switching is used so locking problems are |
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29 | greatly reduced. |
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30 | |
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31 | Although this is the "main" module of the Coro family it provides only |
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32 | low-level functionality. See L<Coro::Process> and related modules for a |
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33 | more useful process abstraction including scheduling. |
10 | |
34 | |
11 | =over 4 |
35 | =over 4 |
12 | |
36 | |
13 | =cut |
37 | =cut |
14 | |
38 | |
15 | package Coro; |
39 | package Coro; |
16 | |
40 | |
17 | BEGIN { |
41 | BEGIN { |
18 | $VERSION = 0.01; |
42 | $VERSION = 0.03; |
19 | |
43 | |
20 | require XSLoader; |
44 | require XSLoader; |
21 | XSLoader::load Coro, $VERSION; |
45 | XSLoader::load Coro, $VERSION; |
22 | } |
46 | } |
23 | |
47 | |
24 | =item $main |
48 | =item $coro = new [$coderef [, @args]] |
25 | |
49 | |
26 | This coroutine represents the main program. |
50 | Create a new coroutine and return it. The first C<transfer> call to this |
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51 | coroutine will start execution at the given coderef. If, the subroutine |
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52 | returns it will be executed again. |
27 | |
53 | |
28 | =item $current |
54 | If the coderef is omitted this function will create a new "empty" |
29 | |
55 | coroutine, i.e. a coroutine that cannot be transfered to but can be used |
30 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
56 | to save the current coroutine in. |
31 | |
57 | |
32 | =cut |
58 | =cut |
33 | |
59 | |
34 | $main = $current = _newprocess { |
60 | sub new { |
35 | # never being called |
61 | my $class = $_[0]; |
36 | }; |
62 | my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; |
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63 | bless _newprocess { |
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64 | do { |
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65 | eval { &$proc }; |
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66 | if ($@) { |
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67 | $error_msg = $@; |
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68 | $error_coro = _newprocess { }; |
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69 | &transfer($error_coro, $error); |
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70 | } |
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71 | } while (1); |
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72 | }, $class; |
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73 | } |
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74 | |
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75 | =item $prev->transfer($next) |
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76 | |
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77 | Save the state of the current subroutine in C<$prev> and switch to the |
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78 | coroutine saved in C<$next>. |
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79 | |
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80 | The "state" of a subroutine only ever includes scope, i.e. lexical |
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81 | variables and the current execution state. It does not save/restore any |
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82 | global variables such as C<$_> or C<$@> or any other special or non |
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83 | special variables. So remember that every function call that might call |
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84 | C<transfer> (such as C<Coro::Channel::put>) might clobber any global |
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85 | and/or special variables. Yes, this is by design ;) You cna always create |
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86 | your own process abstraction model that saves these variables. |
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87 | |
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88 | The easiest way to do this is to create your own scheduling primitive like this: |
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89 | |
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90 | sub schedule { |
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91 | local ($_, $@, ...); |
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92 | $old->transfer($new); |
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93 | } |
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94 | |
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95 | =cut |
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96 | |
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97 | # I call the _transfer function from a perl function |
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98 | # because that way perl saves all important things on |
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99 | # the stack. Actually, I'd do it from within XS, but |
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100 | # I couldn't get it to work. |
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101 | sub transfer { |
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102 | _transfer($_[0], $_[1]); |
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103 | } |
37 | |
104 | |
38 | =item $error, $error_msg, $error_coro |
105 | =item $error, $error_msg, $error_coro |
39 | |
106 | |
40 | This coroutine will be called on fatal errors. C<$error_msg> and |
107 | This coroutine will be called on fatal errors. C<$error_msg> and |
41 | C<$error_coro> return the error message and the error-causing coroutine, |
108 | C<$error_coro> return the error message and the error-causing coroutine |
42 | respectively. |
109 | (NOT an object) respectively. This API might change. |
43 | |
110 | |
44 | =cut |
111 | =cut |
45 | |
112 | |
46 | $error_msg = |
113 | $error_msg = |
47 | $error_coro = undef; |
114 | $error_coro = undef; |
48 | |
115 | |
49 | $error = _newprocess { |
116 | $error = _newprocess { |
50 | print STDERR "FATAL: $error_msg, program aborted\n"; |
117 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
51 | exit 250; |
118 | exit 50; |
52 | }; |
119 | }; |
53 | |
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54 | =item $coro = new $coderef [, @args] |
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55 | |
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56 | Create a new coroutine and return it. The first C<resume> call to this |
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57 | coroutine will start execution at the given coderef. If it returns it |
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58 | should return a coroutine to switch to. If, after returning, the coroutine |
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59 | is C<resume>d again it starts execution again at the givne coderef. |
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60 | |
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61 | =cut |
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62 | |
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63 | sub new { |
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64 | my $class = $_[0]; |
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65 | my $proc = $_[1]; |
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66 | bless _newprocess { |
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67 | do { |
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68 | eval { &$proc->resume }; |
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69 | if ($@) { |
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70 | ($error_msg, $error_coro) = ($@, $current); |
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71 | $error->resume; |
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72 | } |
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73 | } while (); |
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74 | }, $class; |
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75 | } |
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76 | |
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77 | =item $coro->resume |
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78 | |
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79 | Resume execution at the given coroutine. |
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80 | |
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81 | =cut |
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82 | |
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83 | my $prev; |
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84 | |
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85 | sub resume { |
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86 | $prev = $current; $current = $_[0]; |
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87 | _transfer($prev, $current); |
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88 | } |
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89 | |
120 | |
90 | 1; |
121 | 1; |
91 | |
122 | |
92 | =back |
123 | =back |
93 | |
124 | |
94 | =head1 BUGS |
125 | =head1 BUGS |
95 | |
126 | |
96 | This module has not yet been extensively tested. |
127 | This module has not yet been extensively tested. |
97 | |
128 | |
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129 | =head1 SEE ALSO |
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130 | |
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131 | L<Coro::Process>, L<Coro::Signal>. |
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132 | |
98 | =head1 AUTHOR |
133 | =head1 AUTHOR |
99 | |
134 | |
100 | Marc Lehmann <pcg@goof.com> |
135 | Marc Lehmann <pcg@goof.com> |
101 | http://www.goof.com/pcg/marc/ |
136 | http://www.goof.com/pcg/marc/ |
102 | |
137 | |