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| 91 | I<running> interpreter, there is optional support for signalling a pipe |
91 | I<running> interpreter, there is optional support for signalling a pipe |
| 92 | - that means you can also wait for the pipe to become readable (e.g. via |
92 | - that means you can also wait for the pipe to become readable (e.g. via |
| 93 | L<EV> or L<AnyEvent>). This, of course, incurs the overhead of a C<read> |
93 | L<EV> or L<AnyEvent>). This, of course, incurs the overhead of a C<read> |
| 94 | and C<write> syscall. |
94 | and C<write> syscall. |
| 95 | |
95 | |
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96 | =head1 USAGE EXAMPLES |
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97 | |
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98 | =head2 Async::Interrupt to implement race-free signal handling |
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99 | |
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100 | This example uses a single event pipe for all signals, and one |
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101 | Async::Interrupt per signal. |
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102 | |
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103 | First, create the event pipe and hook it into the event loop (this code is |
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104 | actually what L<AnyEvent> uses itself): |
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105 | |
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106 | $SIGPIPE = new Async::Interrupt::EventPipe; |
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107 | $SIGPIPE_W = AnyEvent->io ( |
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108 | fh => $SIGPIPE->fileno, |
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109 | poll => "r", |
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110 | cb => \&_signal_check, |
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111 | ); |
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112 | |
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113 | Then, for each signal to hook, create an Async::Interrupt object. The |
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114 | callback just sets a global variable, as we are only interested in |
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115 | synchronous signals (i.e. when the event loop polls), which is why the |
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116 | pipe draining is not done automatically. |
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117 | |
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118 | my $interrupt = new Async::Interrupt |
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119 | cb => sub { undef $SIGNAL_RECEIVED{$signum} } |
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120 | signal => $signal, |
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121 | pipe => [$SIGPIPE_R->filenos], |
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122 | pipe_autodrain => 0, |
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123 | ; |
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124 | |
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125 | Finally, the I/O callback for the event pipe handles the signals: |
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126 | |
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127 | sub _signal_check { |
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128 | # drain the pipe first |
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129 | $SIGPIPE->drain; |
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130 | |
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131 | # two loops, just to be sure |
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132 | while (%SIGNAL_RECEIVED) { |
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133 | for (keys %SIGNAL_RECEIVED) { |
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134 | delete $SIGNAL_RECEIVED{$_}; |
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135 | warn "signal $_ received\n"; |
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136 | } |
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137 | } |
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138 | } |
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139 | |
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140 | |
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141 | |
| 96 | =head1 THE Async::Interrupt CLASS |
142 | =head1 THE Async::Interrupt CLASS |
| 97 | |
143 | |
| 98 | =over 4 |
144 | =over 4 |
| 99 | |
145 | |
| 100 | =cut |
146 | =cut |
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| 376 | This only works when the pipe was created by Async::Interrupt. |
422 | This only works when the pipe was created by Async::Interrupt. |
| 377 | |
423 | |
| 378 | Async::Interrupt ensures that the reading file descriptor does not change |
424 | Async::Interrupt ensures that the reading file descriptor does not change |
| 379 | it's value. |
425 | it's value. |
| 380 | |
426 | |
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427 | =item $signum = Async::Interrupt::sig2num $signame_or_number |
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428 | |
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429 | =item $signame = Async::Interrupt::sig2name $signame_or_number |
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430 | |
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431 | These two convenience functions simply convert a signal name or number to |
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432 | the corresponding name or number. They are not used by this module and |
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433 | exist just because perl doesn't have a nice way to do this on its own. |
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434 | |
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435 | They will return C<undef> on illegal names or numbers. |
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436 | |
| 381 | =back |
437 | =back |
| 382 | |
438 | |
| 383 | =head1 THE Async::Interrupt::EventPipe CLASS |
439 | =head1 THE Async::Interrupt::EventPipe CLASS |
| 384 | |
440 | |
| 385 | Pipes are the predominent utility to make asynchronous signals |
441 | Pipes are the predominent utility to make asynchronous signals |
