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Revision 1.6 by root, Sat Jan 6 02:45:56 2007 UTC vs.
Revision 1.10 by root, Fri Oct 5 10:57:40 2007 UTC

17 cede; 17 cede;
18 18
19DESCRIPTION 19DESCRIPTION
20 This module collection manages coroutines. Coroutines are similar to 20 This module collection manages coroutines. Coroutines are similar to
21 threads but don't run in parallel at the same time even on SMP machines. 21 threads but don't run in parallel at the same time even on SMP machines.
22 The specific flavor of coroutine use din this module also guarentees you 22 The specific flavor of coroutine used in this module also guarantees you
23 that it will not switch between coroutines unless necessary, at 23 that it will not switch between coroutines unless necessary, at
24 easily-identified points in your program, so locking and parallel access 24 easily-identified points in your program, so locking and parallel access
25 are rarely an issue, making coroutine programming much safer than 25 are rarely an issue, making coroutine programming much safer than
26 threads programming. 26 threads programming.
27 27
41 $current (or as function: current) 41 $current (or as function: current)
42 The current coroutine (the last coroutine switched to). The initial 42 The current coroutine (the last coroutine switched to). The initial
43 value is $main (of course). 43 value is $main (of course).
44 44
45 This variable is strictly *read-only*. It is provided for 45 This variable is strictly *read-only*. It is provided for
46 performance reasons. If performance is not essentiel you are 46 performance reasons. If performance is not essential you are
47 encouraged to use the "Coro::current" function instead. 47 encouraged to use the "Coro::current" function instead.
48 48
49 $idle 49 $idle
50 A callback that is called whenever the scheduler finds no ready 50 A callback that is called whenever the scheduler finds no ready
51 coroutines to run. The default implementation prints "FATAL: 51 coroutines to run. The default implementation prints "FATAL:
66 async { ... } [@args...] 66 async { ... } [@args...]
67 Create a new asynchronous coroutine and return it's coroutine object 67 Create a new asynchronous coroutine and return it's coroutine object
68 (usually unused). When the sub returns the new coroutine is 68 (usually unused). When the sub returns the new coroutine is
69 automatically terminated. 69 automatically terminated.
70 70
71 Calling "exit" in a coroutine will not work correctly, so do not do 71 See the "Coro::State::new" constructor for info about the coroutine
72 that. 72 environment.
73 73
74 When the coroutine dies, the program will exit, just as in the main 74 Calling "exit" in a coroutine will do the same as calling exit
75 program. 75 outside the coroutine. Likewise, when the coroutine dies, the
76 program will exit, just as it would in the main program.
76 77
77 # create a new coroutine that just prints its arguments 78 # create a new coroutine that just prints its arguments
78 async { 79 async {
79 print "@_\n"; 80 print "@_\n";
80 } 1,2,3,4; 81 } 1,2,3,4;
89 be issued in case of an exception instead of terminating the 90 be issued in case of an exception instead of terminating the
90 program, as "async" does. As the coroutine is being reused, stuff 91 program, as "async" does. As the coroutine is being reused, stuff
91 like "on_destroy" will not work in the expected way, unless you call 92 like "on_destroy" will not work in the expected way, unless you call
92 terminate or cancel, which somehow defeats the purpose of pooling. 93 terminate or cancel, which somehow defeats the purpose of pooling.
93 94
94 The priority will be reset to 0 after each job, otherwise the 95 The priority will be reset to 0 after each job, tracing will be
95 coroutine will be re-used "as-is". 96 disabled, the description will be reset and the default output
97 filehandle gets restored, so you can change alkl these. Otherwise
98 the coroutine will be re-used "as-is": most notably if you change
99 other per-coroutine global stuff such as $/ you need to revert that
100 change, which is most simply done by using local as in " local $/ ".
96 101
97 The pool size is limited to 8 idle coroutines (this can be adjusted 102 The pool size is limited to 8 idle coroutines (this can be adjusted
98 by changing $Coro::POOL_SIZE), and there can be as many non-idle 103 by changing $Coro::POOL_SIZE), and there can be as many non-idle
99 coros as required. 104 coros as required.
100 105
101 If you are concerned about pooled coroutines growing a lot because a 106 If you are concerned about pooled coroutines growing a lot because a
102 single "async_pool" used a lot of stackspace you can e.g. 107 single "async_pool" used a lot of stackspace you can e.g.
103 "async_pool { terminate }" once per second or so to slowly replenish 108 "async_pool { terminate }" once per second or so to slowly replenish
104 the pool. 109 the pool. In addition to that, when the stacks used by a handler
110 grows larger than 16kb (adjustable with $Coro::POOL_RSS) it will
111 also exit.
105 112
106 schedule 113 schedule
107 Calls the scheduler. Please note that the current coroutine will not 114 Calls the scheduler. Please note that the current coroutine will not
108 be put into the ready queue, so calling this function usually means 115 be put into the ready queue, so calling this function usually means
109 you will never be called again unless something else (e.g. an event 116 you will never be called again unless something else (e.g. an event
120 # wake up sleeping coroutine 127 # wake up sleeping coroutine
121 $current->ready; 128 $current->ready;
122 undef $current; 129 undef $current;
123 }; 130 };
124 131
125 # call schedule until event occured. 132 # call schedule until event occurred.
126 # in case we are woken up for other reasons 133 # in case we are woken up for other reasons
127 # (current still defined), loop. 134 # (current still defined), loop.
128 Coro::schedule while $current; 135 Coro::schedule while $current;
129 } 136 }
130 137
144 151
145 terminate [arg...] 152 terminate [arg...]
146 Terminates the current coroutine with the given status values (see 153 Terminates the current coroutine with the given status values (see
147 cancel). 154 cancel).
148 155
156 killall
157 Kills/terminates/cancels all coroutines except the currently running
158 one. This is useful after a fork, either in the child or the parent,
159 as usually only one of them should inherit the running coroutines.
160
149 # dynamic methods 161 # dynamic methods
150 162
151 COROUTINE METHODS 163 COROUTINE METHODS
152 These are the methods you can call on coroutine objects. 164 These are the methods you can call on coroutine objects.
153 165
155 Create a new coroutine and return it. When the sub returns the 167 Create a new coroutine and return it. When the sub returns the
156 coroutine automatically terminates as if "terminate" with the 168 coroutine automatically terminates as if "terminate" with the
157 returned values were called. To make the coroutine run you must 169 returned values were called. To make the coroutine run you must
158 first put it into the ready queue by calling the ready method. 170 first put it into the ready queue by calling the ready method.
159 171
160 Calling "exit" in a coroutine will not work correctly, so do not do 172 See "async" and "Coro::State::new" for additional info about the
161 that. 173 coroutine environment.
162 174
163 $success = $coroutine->ready 175 $success = $coroutine->ready
164 Put the given coroutine into the ready queue (according to it's 176 Put the given coroutine into the ready queue (according to it's
165 priority) and return true. If the coroutine is already in the ready 177 priority) and return true. If the coroutine is already in the ready
166 queue, do nothing and return false. 178 queue, do nothing and return false.
173 arguments as status (default: the empty list). Never returns if the 185 arguments as status (default: the empty list). Never returns if the
174 coroutine is the current coroutine. 186 coroutine is the current coroutine.
175 187
176 $coroutine->join 188 $coroutine->join
177 Wait until the coroutine terminates and return any values given to 189 Wait until the coroutine terminates and return any values given to
178 the "terminate" or "cancel" functions. "join" can be called multiple 190 the "terminate" or "cancel" functions. "join" can be called
179 times from multiple coroutine. 191 concurrently from multiple coroutines.
180 192
181 $coroutine->on_destroy (\&cb) 193 $coroutine->on_destroy (\&cb)
182 Registers a callback that is called when this coroutine gets 194 Registers a callback that is called when this coroutine gets
183 destroyed, but before it is joined. The callback gets passed the 195 destroyed, but before it is joined. The callback gets passed the
184 terminate arguments, if any. 196 terminate arguments, if any.
212 $olddesc = $coroutine->desc ($newdesc) 224 $olddesc = $coroutine->desc ($newdesc)
213 Sets (or gets in case the argument is missing) the description for 225 Sets (or gets in case the argument is missing) the description for
214 this coroutine. This is just a free-form string you can associate 226 this coroutine. This is just a free-form string you can associate
215 with a coroutine. 227 with a coroutine.
216 228
229 This method simply sets the "$coroutine->{desc}" member to the given
230 string. You can modify this member directly if you wish.
231
217 GLOBAL FUNCTIONS 232 GLOBAL FUNCTIONS
218 Coro::nready 233 Coro::nready
219 Returns the number of coroutines that are currently in the ready 234 Returns the number of coroutines that are currently in the ready
220 state, i.e. that can be swicthed to. The value 0 means that the only 235 state, i.e. that can be switched to. The value 0 means that the only
221 runnable coroutine is the currently running one, so "cede" would 236 runnable coroutine is the currently running one, so "cede" would
222 have no effect, and "schedule" would cause a deadlock unless there 237 have no effect, and "schedule" would cause a deadlock unless there
223 is an idle handler that wakes up some coroutines. 238 is an idle handler that wakes up some coroutines.
224 239
225 my $guard = Coro::guard { ... } 240 my $guard = Coro::guard { ... }
226 This creates and returns a guard object. Nothing happens until the 241 This creates and returns a guard object. Nothing happens until the
227 objetc gets destroyed, in which case the codeblock given as argument 242 object gets destroyed, in which case the codeblock given as argument
228 will be executed. This is useful to free locks or other resources in 243 will be executed. This is useful to free locks or other resources in
229 case of a runtime error or when the coroutine gets canceled, as in 244 case of a runtime error or when the coroutine gets canceled, as in
230 both cases the guard block will be executed. The guard object 245 both cases the guard block will be executed. The guard object
231 supports only one method, "->cancel", which will keep the codeblock 246 supports only one method, "->cancel", which will keep the codeblock
232 from being executed. 247 from being executed.
246 it, returning the new coderef. This means that the new coderef will 261 it, returning the new coderef. This means that the new coderef will
247 return immediately without blocking, returning nothing, while the 262 return immediately without blocking, returning nothing, while the
248 original code ref will be called (with parameters) from within its 263 original code ref will be called (with parameters) from within its
249 own coroutine. 264 own coroutine.
250 265
251 The reason this fucntion exists is that many event libraries (such 266 The reason this function exists is that many event libraries (such
252 as the venerable Event module) are not coroutine-safe (a weaker form 267 as the venerable Event module) are not coroutine-safe (a weaker form
253 of thread-safety). This means you must not block within event 268 of thread-safety). This means you must not block within event
254 callbacks, otherwise you might suffer from crashes or worse. 269 callbacks, otherwise you might suffer from crashes or worse.
255 270
256 This function allows your callbacks to block by executing them in 271 This function allows your callbacks to block by executing them in
264BUGS/LIMITATIONS 279BUGS/LIMITATIONS
265 - you must make very sure that no coro is still active on global 280 - you must make very sure that no coro is still active on global
266 destruction. very bad things might happen otherwise (usually segfaults). 281 destruction. very bad things might happen otherwise (usually segfaults).
267 282
268 - this module is not thread-safe. You should only ever use this module 283 - this module is not thread-safe. You should only ever use this module
269 from the same thread (this requirement might be losened in the future 284 from the same thread (this requirement might be loosened in the future
270 to allow per-thread schedulers, but Coro::State does not yet allow 285 to allow per-thread schedulers, but Coro::State does not yet allow
271 this). 286 this).
272 287
273SEE ALSO 288SEE ALSO
274 Support/Utility: Coro::Cont, Coro::Specific, Coro::State, Coro::Util. 289 Support/Utility: Coro::Specific, Coro::State, Coro::Util.
275 290
276 Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore, 291 Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore,
277 Coro::SemaphoreSet, Coro::RWLock. 292 Coro::SemaphoreSet, Coro::RWLock.
278 293
279 Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket, 294 Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket,

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