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4SYNOPSIS 4SYNOPSIS
5 use Coro; 5 use Coro;
6 6
7 async { 7 async {
8 # some asynchronous thread of execution 8 # some asynchronous thread of execution
9 print "2\n";
10 cede; # yield back to main
11 print "4\n";
9 }; 12 };
13 print "1\n";
14 cede; # yield to coroutine
15 print "3\n";
16 cede; # and again
10 17
11 # alternatively create an async coroutine like this: 18 # use locking
19 my $lock = new Coro::Semaphore;
20 my $locked;
12 21
13 sub some_func : Coro { 22 $lock->down;
14 # some more async code 23 $locked = 1;
15 } 24 $lock->up;
16
17 cede;
18 25
19DESCRIPTION 26DESCRIPTION
20 This module collection manages coroutines. Coroutines are similar to 27 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. 28 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 29 The specific flavor of coroutine used in this module also guarantees you
23 that it will not switch between coroutines unless necessary, at 30 that it will not switch between coroutines unless necessary, at
24 easily-identified points in your program, so locking and parallel access 31 easily-identified points in your program, so locking and parallel access
25 are rarely an issue, making coroutine programming much safer than 32 are rarely an issue, making coroutine programming much safer than
26 threads programming. 33 threads programming.
27 34
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31 else). 38 else).
32 39
33 In this module, coroutines are defined as "callchain + lexical variables 40 In this module, coroutines are defined as "callchain + lexical variables
34 + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own 41 + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own
35 callchain, its own set of lexicals and its own set of perls most 42 callchain, its own set of lexicals and its own set of perls most
36 important global variables. 43 important global variables (see Coro::State for more configuration).
37 44
38 $main 45 $main
39 This coroutine represents the main program. 46 This coroutine represents the main program.
40 47
41 $current (or as function: current) 48 $current (or as function: current)
42 The current coroutine (the last coroutine switched to). The initial 49 The current coroutine (the last coroutine switched to). The initial
43 value is $main (of course). 50 value is $main (of course).
44 51
45 This variable is strictly *read-only*. It is provided for 52 This variable is strictly *read-only*. It is provided for
46 performance reasons. If performance is not essentiel you are 53 performance reasons. If performance is not essential you are
47 encouraged to use the "Coro::current" function instead. 54 encouraged to use the "Coro::current" function instead.
48 55
49 $idle 56 $idle
50 A callback that is called whenever the scheduler finds no ready 57 A callback that is called whenever the scheduler finds no ready
51 coroutines to run. The default implementation prints "FATAL: 58 coroutines to run. The default implementation prints "FATAL:
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55 This hook is overwritten by modules such as "Coro::Timer" and 62 This hook is overwritten by modules such as "Coro::Timer" and
56 "Coro::Event" to wait on an external event that hopefully wake up a 63 "Coro::Event" to wait on an external event that hopefully wake up a
57 coroutine so the scheduler can run it. 64 coroutine so the scheduler can run it.
58 65
59 Please note that if your callback recursively invokes perl (e.g. for 66 Please note that if your callback recursively invokes perl (e.g. for
60 event handlers), then it must be prepared to be called recursively. 67 event handlers), then it must be prepared to be called recursively
68 itself.
61 69
62 STATIC METHODS 70 STATIC METHODS
63 Static methods are actually functions that operate on the current 71 Static methods are actually functions that operate on the current
64 coroutine only. 72 coroutine only.
65 73
66 async { ... } [@args...] 74 async { ... } [@args...]
67 Create a new asynchronous coroutine and return it's coroutine object 75 Create a new asynchronous coroutine and return it's coroutine object
68 (usually unused). When the sub returns the new coroutine is 76 (usually unused). When the sub returns the new coroutine is
69 automatically terminated. 77 automatically terminated.
70 78
71 Calling "exit" in a coroutine will not work correctly, so do not do 79 See the "Coro::State::new" constructor for info about the coroutine
72 that. 80 environment in which coroutines run.
73 81
74 When the coroutine dies, the program will exit, just as in the main 82 Calling "exit" in a coroutine will do the same as calling exit
75 program. 83 outside the coroutine. Likewise, when the coroutine dies, the
84 program will exit, just as it would in the main program.
76 85
77 # create a new coroutine that just prints its arguments 86 # create a new coroutine that just prints its arguments
78 async { 87 async {
79 print "@_\n"; 88 print "@_\n";
80 } 1,2,3,4; 89 } 1,2,3,4;
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89 be issued in case of an exception instead of terminating the 98 be issued in case of an exception instead of terminating the
90 program, as "async" does. As the coroutine is being reused, stuff 99 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 100 like "on_destroy" will not work in the expected way, unless you call
92 terminate or cancel, which somehow defeats the purpose of pooling. 101 terminate or cancel, which somehow defeats the purpose of pooling.
93 102
94 The priority will be reset to 0 after each job, otherwise the 103 The priority will be reset to 0 after each job, tracing will be
95 coroutine will be re-used "as-is". 104 disabled, the description will be reset and the default output
105 filehandle gets restored, so you can change alkl these. Otherwise
106 the coroutine will be re-used "as-is": most notably if you change
107 other per-coroutine global stuff such as $/ you need to revert that
108 change, which is most simply done by using local as in " local $/ ".
96 109
97 The pool size is limited to 8 idle coroutines (this can be adjusted 110 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 111 by changing $Coro::POOL_SIZE), and there can be as many non-idle
99 coros as required. 112 coros as required.
100 113
101 If you are concerned about pooled coroutines growing a lot because a 114 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. 115 single "async_pool" used a lot of stackspace you can e.g.
103 "async_pool { terminate }" once per second or so to slowly replenish 116 "async_pool { terminate }" once per second or so to slowly replenish
104 the pool. 117 the pool. In addition to that, when the stacks used by a handler
118 grows larger than 16kb (adjustable with $Coro::POOL_RSS) it will
119 also exit.
105 120
106 schedule 121 schedule
107 Calls the scheduler. Please note that the current coroutine will not 122 Calls the scheduler. Please note that the current coroutine will not
108 be put into the ready queue, so calling this function usually means 123 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 124 you will never be called again unless something else (e.g. an event
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120 # wake up sleeping coroutine 135 # wake up sleeping coroutine
121 $current->ready; 136 $current->ready;
122 undef $current; 137 undef $current;
123 }; 138 };
124 139
125 # call schedule until event occured. 140 # call schedule until event occurred.
126 # in case we are woken up for other reasons 141 # in case we are woken up for other reasons
127 # (current still defined), loop. 142 # (current still defined), loop.
128 Coro::schedule while $current; 143 Coro::schedule while $current;
129 } 144 }
130 145
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132 "Cede" to other coroutines. This function puts the current coroutine 147 "Cede" to other coroutines. This function puts the current coroutine
133 into the ready queue and calls "schedule", which has the effect of 148 into the ready queue and calls "schedule", which has the effect of
134 giving up the current "timeslice" to other coroutines of the same or 149 giving up the current "timeslice" to other coroutines of the same or
135 higher priority. 150 higher priority.
136 151
137 Returns true if at least one coroutine switch has happened.
138
139 Coro::cede_notself 152 Coro::cede_notself
140 Works like cede, but is not exported by default and will cede to any 153 Works like cede, but is not exported by default and will cede to any
141 coroutine, regardless of priority, once. 154 coroutine, regardless of priority, once.
142 155
143 Returns true if at least one coroutine switch has happened.
144
145 terminate [arg...] 156 terminate [arg...]
146 Terminates the current coroutine with the given status values (see 157 Terminates the current coroutine with the given status values (see
147 cancel). 158 cancel).
159
160 killall
161 Kills/terminates/cancels all coroutines except the currently running
162 one. This is useful after a fork, either in the child or the parent,
163 as usually only one of them should inherit the running coroutines.
148 164
149 # dynamic methods 165 # dynamic methods
150 166
151 COROUTINE METHODS 167 COROUTINE METHODS
152 These are the methods you can call on coroutine objects. 168 These are the methods you can call on coroutine objects.
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155 Create a new coroutine and return it. When the sub returns the 171 Create a new coroutine and return it. When the sub returns the
156 coroutine automatically terminates as if "terminate" with the 172 coroutine automatically terminates as if "terminate" with the
157 returned values were called. To make the coroutine run you must 173 returned values were called. To make the coroutine run you must
158 first put it into the ready queue by calling the ready method. 174 first put it into the ready queue by calling the ready method.
159 175
160 Calling "exit" in a coroutine will not work correctly, so do not do 176 See "async" and "Coro::State::new" for additional info about the
161 that. 177 coroutine environment.
162 178
163 $success = $coroutine->ready 179 $success = $coroutine->ready
164 Put the given coroutine into the ready queue (according to it's 180 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 181 priority) and return true. If the coroutine is already in the ready
166 queue, do nothing and return false. 182 queue, do nothing and return false.
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173 arguments as status (default: the empty list). Never returns if the 189 arguments as status (default: the empty list). Never returns if the
174 coroutine is the current coroutine. 190 coroutine is the current coroutine.
175 191
176 $coroutine->join 192 $coroutine->join
177 Wait until the coroutine terminates and return any values given to 193 Wait until the coroutine terminates and return any values given to
178 the "terminate" or "cancel" functions. "join" can be called multiple 194 the "terminate" or "cancel" functions. "join" can be called
179 times from multiple coroutine. 195 concurrently from multiple coroutines.
180 196
181 $coroutine->on_destroy (\&cb) 197 $coroutine->on_destroy (\&cb)
182 Registers a callback that is called when this coroutine gets 198 Registers a callback that is called when this coroutine gets
183 destroyed, but before it is joined. The callback gets passed the 199 destroyed, but before it is joined. The callback gets passed the
184 terminate arguments, if any. 200 terminate arguments, if any.
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212 $olddesc = $coroutine->desc ($newdesc) 228 $olddesc = $coroutine->desc ($newdesc)
213 Sets (or gets in case the argument is missing) the description for 229 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 230 this coroutine. This is just a free-form string you can associate
215 with a coroutine. 231 with a coroutine.
216 232
233 This method simply sets the "$coroutine->{desc}" member to the given
234 string. You can modify this member directly if you wish.
235
236 $coroutine->throw ([$scalar])
237 If $throw is specified and defined, it will be thrown as an
238 exception inside the coroutine at the next convinient point in time
239 (usually after it gains control at the next schedule/transfer/cede).
240 Otherwise clears the exception object.
241
242 The exception object will be thrown "as is" with the specified
243 scalar in $@, i.e. if it is a string, no line number or newline will
244 be appended (unlike with "die").
245
246 This can be used as a softer means than "cancel" to ask a coroutine
247 to end itself, although there is no guarentee that the exception
248 will lead to termination, and if the exception isn't caught it might
249 well end the whole program.
250
217 GLOBAL FUNCTIONS 251 GLOBAL FUNCTIONS
218 Coro::nready 252 Coro::nready
219 Returns the number of coroutines that are currently in the ready 253 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 254 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 255 runnable coroutine is the currently running one, so "cede" would
222 have no effect, and "schedule" would cause a deadlock unless there 256 have no effect, and "schedule" would cause a deadlock unless there
223 is an idle handler that wakes up some coroutines. 257 is an idle handler that wakes up some coroutines.
224 258
225 my $guard = Coro::guard { ... } 259 my $guard = Coro::guard { ... }
226 This creates and returns a guard object. Nothing happens until the 260 This creates and returns a guard object. Nothing happens until the
227 objetc gets destroyed, in which case the codeblock given as argument 261 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 262 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 263 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 264 both cases the guard block will be executed. The guard object
231 supports only one method, "->cancel", which will keep the codeblock 265 supports only one method, "->cancel", which will keep the codeblock
232 from being executed. 266 from being executed.
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246 it, returning the new coderef. This means that the new coderef will 280 it, returning the new coderef. This means that the new coderef will
247 return immediately without blocking, returning nothing, while the 281 return immediately without blocking, returning nothing, while the
248 original code ref will be called (with parameters) from within its 282 original code ref will be called (with parameters) from within its
249 own coroutine. 283 own coroutine.
250 284
251 The reason this fucntion exists is that many event libraries (such 285 The reason this function exists is that many event libraries (such
252 as the venerable Event module) are not coroutine-safe (a weaker form 286 as the venerable Event module) are not coroutine-safe (a weaker form
253 of thread-safety). This means you must not block within event 287 of thread-safety). This means you must not block within event
254 callbacks, otherwise you might suffer from crashes or worse. 288 callbacks, otherwise you might suffer from crashes or worse.
255 289
256 This function allows your callbacks to block by executing them in 290 This function allows your callbacks to block by executing them in
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264BUGS/LIMITATIONS 298BUGS/LIMITATIONS
265 - you must make very sure that no coro is still active on global 299 - you must make very sure that no coro is still active on global
266 destruction. very bad things might happen otherwise (usually segfaults). 300 destruction. very bad things might happen otherwise (usually segfaults).
267 301
268 - this module is not thread-safe. You should only ever use this module 302 - 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 303 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 304 to allow per-thread schedulers, but Coro::State does not yet allow
271 this). 305 this).
272 306
273SEE ALSO 307SEE ALSO
308 Lower level Configuration, Coroutine Environment: Coro::State.
309
310 Debugging: Coro::Debug.
311
274 Support/Utility: Coro::Cont, Coro::Specific, Coro::State, Coro::Util. 312 Support/Utility: Coro::Specific, Coro::Util.
275 313
276 Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore, 314 Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore,
277 Coro::SemaphoreSet, Coro::RWLock. 315 Coro::SemaphoreSet, Coro::RWLock.
278 316
279 Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket, 317 Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket.
280 Coro::Select.
281 318
319 Compatibility: Coro::LWP, Coro::Storable, Coro::Select.
320
282 Embedding: <Coro:MakeMaker> 321 Embedding: <Coro:MakeMaker>.
283 322
284AUTHOR 323AUTHOR
285 Marc Lehmann <schmorp@schmorp.de> 324 Marc Lehmann <schmorp@schmorp.de>
286 http://home.schmorp.de/ 325 http://home.schmorp.de/
287 326

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