… | |
… | |
53 | |
53 | |
54 | For example the deliantra game server uses a variant of this technique |
54 | For example the deliantra game server uses a variant of this technique |
55 | to interrupt background processes regularly to send map updates to game |
55 | to interrupt background processes regularly to send map updates to game |
56 | clients. |
56 | clients. |
57 | |
57 | |
|
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58 | Or L<EV::Loop::Async> uses an interrupt object to wake up perl when new |
|
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59 | events have arrived. |
|
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60 | |
58 | L<IO::AIO> and L<BDB> could also use this to speed up result reporting. |
61 | L<IO::AIO> and L<BDB> could also use this to speed up result reporting. |
59 | |
62 | |
60 | =item Speedy event loop invocation |
63 | =item Speedy event loop invocation |
61 | |
64 | |
62 | One could use this module e.g. in L<Coro> to interrupt a running coro-thread |
65 | One could use this module e.g. in L<Coro> to interrupt a running coro-thread |
… | |
… | |
88 | I<running> interpreter, there is optional support for signalling a pipe |
91 | I<running> interpreter, there is optional support for signalling a pipe |
89 | - 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 |
90 | 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> |
91 | and C<write> syscall. |
94 | and C<write> syscall. |
92 | |
95 | |
|
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96 | =head1 USAGE EXAMPLES |
|
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97 | |
|
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98 | =head2 Implementing 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. This code is actually what the L<AnyEvent> |
|
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102 | module uses itself when Async::Interrupt is available. |
|
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103 | |
|
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104 | First, create the event pipe and hook it into the event loop |
|
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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, # defined later |
|
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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 => $signum, |
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121 | pipe => [$SIGPIPE->filenos], |
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122 | pipe_autodrain => 0, |
|
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123 | ; |
|
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124 | |
|
|
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 | |
|
|
140 | =head2 Interrupt perl from another thread |
|
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141 | |
|
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142 | This example interrupts the Perl interpreter from another thread, via the |
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143 | XS API. This is used by e.g. the L<EV::Loop::Async> module. |
|
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144 | |
|
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145 | On the Perl level, a new loop object (which contains the thread) |
|
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146 | is created, by first calling some XS constructor, querying the |
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147 | C-level callback function and feeding that as the C<c_cb> into the |
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148 | Async::Interrupt constructor: |
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149 | |
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150 | my $self = XS_thread_constructor; |
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151 | my ($c_func, $c_arg) = _c_func $self; # return the c callback |
|
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152 | my $asy = new Async::Interrupt c_cb => [$c_func, $c_arg]; |
|
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153 | |
|
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154 | Then the newly created Interrupt object is queried for the signaling |
|
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155 | function that the newly created thread should call, and this is in turn |
|
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156 | told to the thread object: |
|
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157 | |
|
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158 | _attach $self, $asy->signal_func; |
|
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159 | |
|
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160 | So to repeat: first the XS object is created, then it is queried for the |
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161 | callback that should be called when the Interrupt object gets signalled. |
|
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162 | |
|
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163 | Then the interrupt object is queried for the callback fucntion that the |
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164 | thread should call to signal the Interrupt object, and this callback is |
|
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165 | then attached to the thread. |
|
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166 | |
|
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167 | You have to be careful that your new thread is not signalling before the |
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168 | signal function was configured, for example by starting the background |
|
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169 | thread only within C<_attach>. |
|
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170 | |
|
|
171 | That concludes the Perl part. |
|
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172 | |
|
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173 | The XS part consists of the actual constructor which creates a thread, |
|
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174 | which is not relevant for this example, and two functions, C<_c_func>, |
|
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175 | which returns the Perl-side callback, and C<_attach>, which configures |
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176 | the signalling functioon that is safe toc all from another thread. For |
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177 | simplicity, we will use global variables to store the functions, normally |
|
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178 | you would somehow attach them to C<$self>. |
|
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179 | |
|
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180 | The C<c_func> simply returns the address of a static function and arranges |
|
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181 | for the object pointed to by C<$self> to be passed to it, as an integer: |
|
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182 | |
|
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183 | void |
|
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184 | _c_func (SV *loop) |
|
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185 | PPCODE: |
|
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186 | EXTEND (SP, 2); |
|
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187 | PUSHs (sv_2mortal (newSViv (PTR2IV (c_func)))); |
|
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188 | PUSHs (sv_2mortal (newSViv (SvRV (loop)))); |
|
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189 | |
|
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190 | This would be the callback (since it runs in a normal Perl context, it is |
|
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191 | permissible to manipulate Perl values): |
|
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192 | |
|
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193 | static void |
|
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194 | c_func (pTHX_ void *loop_, int value) |
|
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195 | { |
|
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196 | SV *loop_object = (SV *)loop_; |
|
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197 | ... |
|
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198 | } |
|
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199 | |
|
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200 | And this attaches the signalling callback: |
|
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201 | |
|
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202 | static void (*my_sig_func) (void *signal_arg, int value); |
|
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203 | static void *my_sig_arg; |
|
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204 | |
|
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205 | void |
|
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206 | _attach (SV *loop_, IV sig_func, void *sig_arg) |
|
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207 | CODE: |
|
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208 | { |
|
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209 | my_sig_func = sig_func; |
|
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210 | my_sig_arg = sig_arg; |
|
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211 | |
|
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212 | /* now run the thread */ |
|
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213 | thread_create (&u->tid, l_run, 0); |
|
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214 | } |
|
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215 | |
|
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216 | And C<l_run> (the background thread) would eventually call the signaling |
|
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217 | function: |
|
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218 | |
|
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219 | my_sig_func (my_sig_arg, 0); |
|
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220 | |
|
|
221 | You can have a look at L<EV::Loop::Async> for an actual example using |
|
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222 | intra-thread communication, locking and so on. |
|
|
223 | |
|
|
224 | |
|
|
225 | =head1 THE Async::Interrupt CLASS |
|
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226 | |
93 | =over 4 |
227 | =over 4 |
94 | |
228 | |
95 | =cut |
229 | =cut |
96 | |
230 | |
97 | package Async::Interrupt; |
231 | package Async::Interrupt; |
98 | |
232 | |
99 | use common::sense; |
233 | use common::sense; |
100 | |
234 | |
101 | BEGIN { |
235 | BEGIN { |
102 | # the next line forces initialisation of internal |
236 | # the next line forces initialisation of internal |
103 | # signal handling # variables |
237 | # signal handling variables, otherwise, PL_sig_pending |
|
|
238 | # etc. might be null pointers. |
104 | $SIG{KILL} = sub { }; |
239 | $SIG{KILL} = sub { }; |
105 | |
240 | |
106 | our $VERSION = '0.041'; |
241 | our $VERSION = '1.05'; |
107 | |
242 | |
108 | require XSLoader; |
243 | require XSLoader; |
109 | XSLoader::load ("Async::Interrupt", $VERSION); |
244 | XSLoader::load ("Async::Interrupt", $VERSION); |
110 | } |
245 | } |
111 | |
246 | |
… | |
… | |
134 | The exceptions are C<$!> and C<$@>, which are saved and restored by |
269 | The exceptions are C<$!> and C<$@>, which are saved and restored by |
135 | Async::Interrupt. |
270 | Async::Interrupt. |
136 | |
271 | |
137 | If the callback should throw an exception, then it will be caught, |
272 | If the callback should throw an exception, then it will be caught, |
138 | and C<$Async::Interrupt::DIED> will be called with C<$@> containing |
273 | and C<$Async::Interrupt::DIED> will be called with C<$@> containing |
139 | the exception. The default will simply C<warn> about the message and |
274 | the exception. The default will simply C<warn> about the message and |
140 | continue. |
275 | continue. |
141 | |
276 | |
142 | =item c_cb => [$c_func, $c_arg] |
277 | =item c_cb => [$c_func, $c_arg] |
143 | |
278 | |
144 | Registers a C callback the be invoked whenever the async interrupt is |
279 | Registers a C callback the be invoked whenever the async interrupt is |
… | |
… | |
157 | might use (the exception is C<errno>, which is saved and restored by |
292 | might use (the exception is C<errno>, which is saved and restored by |
158 | Async::Interrupt). The callback itself runs as part of the perl context, |
293 | Async::Interrupt). The callback itself runs as part of the perl context, |
159 | so you can call any perl functions and modify any perl data structures (in |
294 | so you can call any perl functions and modify any perl data structures (in |
160 | which case the requirements set out for C<cb> apply as well). |
295 | which case the requirements set out for C<cb> apply as well). |
161 | |
296 | |
|
|
297 | =item var => $scalar_ref |
|
|
298 | |
|
|
299 | When specified, then the given argument must be a reference to a |
|
|
300 | scalar. The scalar will be set to C<0> initially. Signalling the interrupt |
|
|
301 | object will set it to the passed value, handling the interrupt will reset |
|
|
302 | it to C<0> again. |
|
|
303 | |
|
|
304 | Note that the only thing you are legally allowed to do is to is to check |
|
|
305 | the variable in a boolean or integer context (e.g. comparing it with a |
|
|
306 | string, or printing it, will I<destroy> it and might cause your program to |
|
|
307 | crash or worse). |
|
|
308 | |
162 | =item signal => $signame_or_value |
309 | =item signal => $signame_or_value |
163 | |
310 | |
164 | When this parameter is specified, then the Async::Interrupt will hook the |
311 | When this parameter is specified, then the Async::Interrupt will hook the |
165 | given signal, that is, it will effectively call C<< ->signal (0) >> each time |
312 | given signal, that is, it will effectively call C<< ->signal (0) >> each time |
166 | the given signal is caught by the process. |
313 | the given signal is caught by the process. |
167 | |
314 | |
168 | Only one async can hook a given signal, and the signal will be restored to |
315 | Only one async can hook a given signal, and the signal will be restored to |
169 | defaults when the Async::Interrupt object gets destroyed. |
316 | defaults when the Async::Interrupt object gets destroyed. |
|
|
317 | |
|
|
318 | =item signal_hysteresis => $boolean |
|
|
319 | |
|
|
320 | Sets the initial signal hysteresis state, see the C<signal_hysteresis> |
|
|
321 | method, below. |
170 | |
322 | |
171 | =item pipe => [$fileno_or_fh_for_reading, $fileno_or_fh_for_writing] |
323 | =item pipe => [$fileno_or_fh_for_reading, $fileno_or_fh_for_writing] |
172 | |
324 | |
173 | Specifies two file descriptors (or file handles) that should be signalled |
325 | Specifies two file descriptors (or file handles) that should be signalled |
174 | whenever the async interrupt is signalled. This means a single octet will |
326 | whenever the async interrupt is signalled. This means a single octet will |
175 | be written to it, and before the callback is being invoked, it will be |
327 | be written to it, and before the callback is being invoked, it will be |
176 | read again. Due to races, it is unlikely but possible that multiple octets |
328 | read again. Due to races, it is unlikely but possible that multiple octets |
177 | are written. It is required that the file handles are both in nonblocking |
329 | are written. It is required that the file handles are both in nonblocking |
178 | mode. |
330 | mode. |
179 | |
331 | |
180 | You can get a portable pipe and set non-blocking mode portably by using |
|
|
181 | e.g. L<AnyEvent::Util> from the L<AnyEvent> distribution. |
|
|
182 | |
|
|
183 | It is also possible to pass in a linux eventfd as both read and write |
|
|
184 | handle (which is faster than a pipe). |
|
|
185 | |
|
|
186 | The object will keep a reference to the file handles. |
332 | The object will keep a reference to the file handles. |
187 | |
333 | |
188 | This can be used to ensure that async notifications will interrupt event |
334 | This can be used to ensure that async notifications will interrupt event |
189 | frameworks as well. |
335 | frameworks as well. |
190 | |
336 | |
|
|
337 | Note that C<Async::Interrupt> will create a suitable signal fd |
|
|
338 | automatically when your program requests one, so you don't have to specify |
|
|
339 | this argument when all you want is an extra file descriptor to watch. |
|
|
340 | |
|
|
341 | If you want to share a single event pipe between multiple Async::Interrupt |
|
|
342 | objects, you can use the C<Async::Interrupt::EventPipe> class to manage |
|
|
343 | those. |
|
|
344 | |
|
|
345 | =item pipe_autodrain => $boolean |
|
|
346 | |
|
|
347 | Sets the initial autodrain state, see the C<pipe_autodrain> method, below. |
|
|
348 | |
191 | =back |
349 | =back |
192 | |
350 | |
193 | =cut |
351 | =cut |
194 | |
352 | |
195 | sub new { |
353 | sub new { |
196 | my ($class, %arg) = @_; |
354 | my ($class, %arg) = @_; |
197 | |
355 | |
198 | bless \(_alloc $arg{cb}, @{$arg{c_cb}}[0,1], @{$arg{pipe}}[0,1], $arg{signal}), $class |
356 | my $self = bless \(_alloc $arg{cb}, @{$arg{c_cb}}[0,1], @{$arg{pipe}}[0,1], $arg{signal}, $arg{var}), $class; |
|
|
357 | |
|
|
358 | # urgs, reminds me of Event |
|
|
359 | for my $attr (qw(pipe_autodrain signal_hysteresis)) { |
|
|
360 | $self->$attr ($arg{$attr}) if exists $arg{$attr}; |
|
|
361 | } |
|
|
362 | |
|
|
363 | $self |
199 | } |
364 | } |
200 | |
365 | |
201 | =item ($signal_func, $signal_arg) = $async->signal_func |
366 | =item ($signal_func, $signal_arg) = $async->signal_func |
202 | |
367 | |
203 | Returns the address of a function to call asynchronously. The function has |
368 | Returns the address of a function to call asynchronously. The function |
204 | the following prototype and needs to be passed the specified C<$c_arg>, |
369 | has the following prototype and needs to be passed the specified |
205 | which is a C<void *> cast to C<IV>: |
370 | C<$signal_arg>, which is a C<void *> cast to C<IV>: |
206 | |
371 | |
207 | void (*signal_func) (void *signal_arg, int value) |
372 | void (*signal_func) (void *signal_arg, int value) |
208 | |
373 | |
209 | An example call would look like: |
374 | An example call would look like: |
210 | |
375 | |
211 | signal_func (signal_arg, 0); |
376 | signal_func (signal_arg, 0); |
212 | |
377 | |
213 | The function is safe to call from within signal and thread contexts, at |
378 | The function is safe to call from within signal and thread contexts, at |
214 | any time. The specified C<value> is passed to both C and Perl callback. |
379 | any time. The specified C<value> is passed to both C and Perl callback. |
215 | |
380 | |
216 | C<$value> must be in the valid range for a C<sig_atomic_t> (0..127 is |
381 | C<$value> must be in the valid range for a C<sig_atomic_t>, except C<0> |
217 | portable). |
382 | (1..127 is portable). |
218 | |
383 | |
219 | If the function is called while the Async::Interrupt object is already |
384 | If the function is called while the Async::Interrupt object is already |
220 | signaled but before the callbacks are being executed, then the stored |
385 | signaled but before the callbacks are being executed, then the stored |
221 | C<value> is either the old or the new one. Due to the asynchronous |
386 | C<value> is either the old or the new one. Due to the asynchronous |
222 | nature of the code, the C<value> can even be passed to two consecutive |
387 | nature of the code, the C<value> can even be passed to two consecutive |
223 | invocations of the callback. |
388 | invocations of the callback. |
224 | |
389 | |
|
|
390 | =item $address = $async->c_var |
|
|
391 | |
|
|
392 | Returns the address (cast to IV) of an C<IV> variable. The variable is set |
|
|
393 | to C<0> initially and gets set to the passed value whenever the object |
|
|
394 | gets signalled, and reset to C<0> once the interrupt has been handled. |
|
|
395 | |
|
|
396 | Note that it is often beneficial to just call C<PERL_ASYNC_CHECK ()> to |
|
|
397 | handle any interrupts. |
|
|
398 | |
|
|
399 | Example: call some XS function to store the address, then show C code |
|
|
400 | waiting for it. |
|
|
401 | |
|
|
402 | my_xs_func $async->c_var; |
|
|
403 | |
|
|
404 | static IV *valuep; |
|
|
405 | |
|
|
406 | void |
|
|
407 | my_xs_func (void *addr) |
|
|
408 | CODE: |
|
|
409 | valuep = (IV *)addr; |
|
|
410 | |
|
|
411 | // code in a loop, waiting |
|
|
412 | while (!*valuep) |
|
|
413 | ; // do something |
|
|
414 | |
225 | =item $async->signal ($value=0) |
415 | =item $async->signal ($value=1) |
226 | |
416 | |
227 | This signals the given async object from Perl code. Semi-obviously, this |
417 | This signals the given async object from Perl code. Semi-obviously, this |
228 | will instantly trigger the callback invocation. |
418 | will instantly trigger the callback invocation (it does not, as the name |
|
|
419 | might imply, do anything with POSIX signals). |
229 | |
420 | |
230 | C<$value> must be in the valid range for a C<sig_atomic_t> (0..127 is |
421 | C<$value> must be in the valid range for a C<sig_atomic_t>, except C<0> |
231 | portable). |
422 | (1..127 is portable). |
|
|
423 | |
|
|
424 | =item $async->signal_hysteresis ($enable) |
|
|
425 | |
|
|
426 | Enables or disables signal hysteresis (default: disabled). If a POSIX |
|
|
427 | signal is used as a signal source for the interrupt object, then enabling |
|
|
428 | signal hysteresis causes Async::Interrupt to reset the signal action to |
|
|
429 | C<SIG_IGN> in the signal handler and restore it just before handling the |
|
|
430 | interruption. |
|
|
431 | |
|
|
432 | When you expect a lot of signals (e.g. when using SIGIO), then enabling |
|
|
433 | signal hysteresis can reduce the number of handler invocations |
|
|
434 | considerably, at the cost of two extra syscalls. |
|
|
435 | |
|
|
436 | Note that setting the signal to C<SIG_IGN> can have unintended side |
|
|
437 | effects when you fork and exec other programs, as often they do not expect |
|
|
438 | signals to be ignored by default. |
232 | |
439 | |
233 | =item $async->block |
440 | =item $async->block |
234 | |
441 | |
235 | =item $async->unblock |
442 | =item $async->unblock |
236 | |
443 | |
… | |
… | |
251 | This call C<< $async->block >> and installs a handler that is called when |
458 | This call C<< $async->block >> and installs a handler that is called when |
252 | the current scope is exited (via an exception, by canceling the Coro |
459 | the current scope is exited (via an exception, by canceling the Coro |
253 | thread, by calling last/goto etc.). |
460 | thread, by calling last/goto etc.). |
254 | |
461 | |
255 | This is the recommended (and fastest) way to implement critical sections. |
462 | This is the recommended (and fastest) way to implement critical sections. |
|
|
463 | |
|
|
464 | =item ($block_func, $block_arg) = $async->scope_block_func |
|
|
465 | |
|
|
466 | Returns the address of a function that implements the C<scope_block> |
|
|
467 | functionality. |
|
|
468 | |
|
|
469 | It has the following prototype and needs to be passed the specified |
|
|
470 | C<$block_arg>, which is a C<void *> cast to C<IV>: |
|
|
471 | |
|
|
472 | void (*block_func) (void *block_arg) |
|
|
473 | |
|
|
474 | An example call would look like: |
|
|
475 | |
|
|
476 | block_func (block_arg); |
|
|
477 | |
|
|
478 | The function is safe to call only from within the toplevel of a perl XS |
|
|
479 | function and will call C<LEAVE> and C<ENTER> (in this order!). |
256 | |
480 | |
257 | =item $async->pipe_enable |
481 | =item $async->pipe_enable |
258 | |
482 | |
259 | =item $async->pipe_disable |
483 | =item $async->pipe_disable |
260 | |
484 | |
… | |
… | |
262 | enabled). Writing to a pipe is relatively expensive, so it can be disabled |
486 | enabled). Writing to a pipe is relatively expensive, so it can be disabled |
263 | when you know you are not waiting for it (for example, with L<EV> you |
487 | when you know you are not waiting for it (for example, with L<EV> you |
264 | could disable the pipe in a check watcher, and enable it in a prepare |
488 | could disable the pipe in a check watcher, and enable it in a prepare |
265 | watcher). |
489 | watcher). |
266 | |
490 | |
267 | Note that when C<fd_disable> is in effect, no attempt to read from the |
491 | Note that currently, while C<pipe_disable> is in effect, no attempt to |
268 | pipe will be done. |
492 | read from the pipe will be done when handling events. This might change as |
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493 | soon as I realize why this is a mistake. |
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494 | |
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495 | =item $fileno = $async->pipe_fileno |
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496 | |
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497 | Returns the reading side of the signalling pipe. If no signalling pipe is |
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498 | currently attached to the object, it will dynamically create one. |
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499 | |
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500 | Note that the only valid oepration on this file descriptor is to wait |
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501 | until it is readable. The fd might belong currently to a pipe, a tcp |
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502 | socket, or an eventfd, depending on the platform, and is guaranteed to be |
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503 | C<select>able. |
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504 | |
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505 | =item $async->pipe_autodrain ($enable) |
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506 | |
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507 | Enables (C<1>) or disables (C<0>) automatic draining of the pipe (default: |
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508 | enabled). When automatic draining is enabled, then Async::Interrupt will |
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509 | automatically clear the pipe. Otherwise the user is responsible for this |
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510 | draining. |
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511 | |
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512 | This is useful when you want to share one pipe among many Async::Interrupt |
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513 | objects. |
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514 | |
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515 | =item $async->post_fork |
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516 | |
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517 | The object will not normally be usable after a fork (as the pipe fd is |
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518 | shared between processes). Calling this method after a fork in the child |
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519 | ensures that the object will work as expected again. It only needs to be |
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520 | called when the async object is used in the child. |
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521 | |
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522 | This only works when the pipe was created by Async::Interrupt. |
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523 | |
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524 | Async::Interrupt ensures that the reading file descriptor does not change |
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525 | it's value. |
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526 | |
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527 | =item $signum = Async::Interrupt::sig2num $signame_or_number |
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528 | |
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529 | =item $signame = Async::Interrupt::sig2name $signame_or_number |
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530 | |
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531 | These two convenience functions simply convert a signal name or number to |
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532 | the corresponding name or number. They are not used by this module and |
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533 | exist just because perl doesn't have a nice way to do this on its own. |
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534 | |
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535 | They will return C<undef> on illegal names or numbers. |
|
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536 | |
|
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537 | =back |
|
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538 | |
|
|
539 | =head1 THE Async::Interrupt::EventPipe CLASS |
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540 | |
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541 | Pipes are the predominant utility to make asynchronous signals |
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542 | synchronous. However, pipes are hard to come by: they don't exist on the |
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543 | broken windows platform, and on GNU/Linux systems, you might want to use |
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544 | an C<eventfd> instead. |
|
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545 | |
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546 | This class creates selectable event pipes in a portable fashion: on |
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547 | windows, it will try to create a tcp socket pair, on GNU/Linux, it will |
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548 | try to create an eventfd and everywhere else it will try to use a normal |
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549 | pipe. |
|
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550 | |
|
|
551 | =over 4 |
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552 | |
|
|
553 | =item $epipe = new Async::Interrupt::EventPipe |
|
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554 | |
|
|
555 | This creates and returns an eventpipe object. This object is simply a |
|
|
556 | blessed array reference: |
|
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557 | |
|
|
558 | =item ($r_fd, $w_fd) = $epipe->filenos |
|
|
559 | |
|
|
560 | Returns the read-side file descriptor and the write-side file descriptor. |
|
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561 | |
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562 | Example: pass an eventpipe object as pipe to the Async::Interrupt |
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|
563 | constructor, and create an AnyEvent watcher for the read side. |
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564 | |
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|
565 | my $epipe = new Async::Interrupt::EventPipe; |
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|
566 | my $asy = new Async::Interrupt pipe => [$epipe->filenos]; |
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567 | my $iow = AnyEvent->io (fh => $epipe->fileno, poll => 'r', cb => sub { }); |
|
|
568 | |
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|
569 | =item $r_fd = $epipe->fileno |
|
|
570 | |
|
|
571 | Return only the reading/listening side. |
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|
572 | |
|
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573 | =item $epipe->signal |
|
|
574 | |
|
|
575 | Write something to the pipe, in a portable fashion. |
|
|
576 | |
|
|
577 | =item $epipe->drain |
|
|
578 | |
|
|
579 | Drain (empty) the pipe. |
|
|
580 | |
|
|
581 | =item ($c_func, $c_arg) = $epipe->signal_func |
|
|
582 | |
|
|
583 | =item ($c_func, $c_arg) = $epipe->drain_func |
|
|
584 | |
|
|
585 | These two methods returns a function pointer and C<void *> argument |
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|
586 | that can be called to have the effect of C<< $epipe->signal >> or C<< |
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|
587 | $epipe->drain >>, respectively, on the XS level. |
|
|
588 | |
|
|
589 | They both have the following prototype and need to be passed their |
|
|
590 | C<$c_arg>, which is a C<void *> cast to an C<IV>: |
|
|
591 | |
|
|
592 | void (*c_func) (void *c_arg) |
|
|
593 | |
|
|
594 | An example call would look like: |
|
|
595 | |
|
|
596 | c_func (c_arg); |
|
|
597 | |
|
|
598 | =item $epipe->renew |
|
|
599 | |
|
|
600 | Recreates the pipe (useful after a fork). The reading side will not change |
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|
601 | it's file descriptor number, but the writing side might. |
|
|
602 | |
|
|
603 | =item $epipe->wait |
|
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604 | |
|
|
605 | This method blocks the process until there are events on the pipe. This is |
|
|
606 | not a very event-based or ncie way of usign an event pipe, but it can be |
|
|
607 | occasionally useful. |
|
|
608 | |
|
|
609 | =back |
269 | |
610 | |
270 | =cut |
611 | =cut |
271 | |
612 | |
272 | 1; |
613 | 1; |
273 | |
|
|
274 | =back |
|
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275 | |
|
|
276 | =head1 EXAMPLE |
|
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277 | |
|
|
278 | There really should be a complete C/XS example. Bug me about it. Better |
|
|
279 | yet, create one. |
|
|
280 | |
614 | |
281 | =head1 IMPLEMENTATION DETAILS AND LIMITATIONS |
615 | =head1 IMPLEMENTATION DETAILS AND LIMITATIONS |
282 | |
616 | |
283 | This module works by "hijacking" SIGKILL, which is guaranteed to always |
617 | This module works by "hijacking" SIGKILL, which is guaranteed to always |
284 | exist, but also cannot be caught, so is always available. |
618 | exist, but also cannot be caught, so is always available. |
… | |
… | |
287 | then intercepts the interpreter handling it. This makes normal signal |
621 | then intercepts the interpreter handling it. This makes normal signal |
288 | handling slower (probably unmeasurably, though), but has the advantage |
622 | handling slower (probably unmeasurably, though), but has the advantage |
289 | of not requiring a special runops function, nor slowing down normal perl |
623 | of not requiring a special runops function, nor slowing down normal perl |
290 | execution a bit. |
624 | execution a bit. |
291 | |
625 | |
292 | It assumes that C<sig_atomic_t> and C<int> are both async-safe to modify |
626 | It assumes that C<sig_atomic_t>, C<int> and C<IV> are all async-safe to |
293 | (C<sig_atomic_> is used by this module, and perl itself uses C<int>, so we |
627 | modify. |
294 | can assume that this is quite portable, at least w.r.t. signals). |
|
|
295 | |
628 | |
296 | =head1 AUTHOR |
629 | =head1 AUTHOR |
297 | |
630 | |
298 | Marc Lehmann <schmorp@schmorp.de> |
631 | Marc Lehmann <schmorp@schmorp.de> |
299 | http://home.schmorp.de/ |
632 | http://home.schmorp.de/ |