1 | NAME |
1 | NAME |
2 | Coro - coroutine process abstraction |
2 | Coro - the only real threads in perl |
3 | |
3 | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use Coro; |
5 | use Coro; |
6 | |
6 | |
7 | async { |
7 | async { |
… | |
… | |
9 | print "2\n"; |
9 | print "2\n"; |
10 | cede; # yield back to main |
10 | cede; # yield back to main |
11 | print "4\n"; |
11 | print "4\n"; |
12 | }; |
12 | }; |
13 | print "1\n"; |
13 | print "1\n"; |
14 | cede; # yield to coroutine |
14 | cede; # yield to coro |
15 | print "3\n"; |
15 | print "3\n"; |
16 | cede; # and again |
16 | cede; # and again |
17 | |
17 | |
18 | # use locking |
18 | # use locking |
19 | use Coro::Semaphore; |
19 | use Coro::Semaphore; |
… | |
… | |
23 | $lock->down; |
23 | $lock->down; |
24 | $locked = 1; |
24 | $locked = 1; |
25 | $lock->up; |
25 | $lock->up; |
26 | |
26 | |
27 | DESCRIPTION |
27 | DESCRIPTION |
28 | This module collection manages coroutines. Coroutines are similar to |
28 | For a tutorial-style introduction, please read the Coro::Intro manpage. |
29 | threads but don't (in general) run in parallel at the same time even on |
29 | This manpage mainly contains reference information. |
30 | SMP machines. The specific flavor of coroutine used in this module also |
30 | |
31 | guarantees you that it will not switch between coroutines unless |
31 | This module collection manages continuations in general, most often in |
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32 | the form of cooperative threads (also called coros, or simply "coro" in |
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33 | the documentation). They are similar to kernel threads but don't (in |
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34 | general) run in parallel at the same time even on SMP machines. The |
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35 | specific flavor of thread offered by this module also guarantees you |
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36 | that it will not switch between threads unless necessary, at |
32 | necessary, at easily-identified points in your program, so locking and |
37 | easily-identified points in your program, so locking and parallel access |
33 | parallel access are rarely an issue, making coroutine programming much |
38 | are rarely an issue, making thread programming much safer and easier |
34 | safer and easier than threads programming. |
39 | than using other thread models. |
35 | |
40 | |
36 | Unlike a normal perl program, however, coroutines allow you to have |
41 | Unlike the so-called "Perl threads" (which are not actually real threads |
37 | multiple running interpreters that share data, which is especially |
42 | but only the windows process emulation ported to unix, and as such act |
38 | useful to code pseudo-parallel processes and for event-based |
43 | as processes), Coro provides a full shared address space, which makes |
39 | programming, such as multiple HTTP-GET requests running concurrently. |
44 | communication between threads very easy. And Coro's threads are fast, |
40 | See Coro::AnyEvent to learn more. |
45 | too: disabling the Windows process emulation code in your perl and using |
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46 | Coro can easily result in a two to four times speed increase for your |
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47 | programs. A parallel matrix multiplication benchmark runs over 300 times |
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48 | faster on a single core than perl's pseudo-threads on a quad core using |
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49 | all four cores. |
41 | |
50 | |
42 | Coroutines are also useful because Perl has no support for threads (the |
51 | Coro achieves that by supporting multiple running interpreters that |
43 | so called "threads" that perl offers are nothing more than the (bad) |
52 | share data, which is especially useful to code pseudo-parallel processes |
44 | process emulation coming from the Windows platform: On standard |
53 | and for event-based programming, such as multiple HTTP-GET requests |
45 | operating systems they serve no purpose whatsoever, except by making |
54 | running concurrently. See Coro::AnyEvent to learn more on how to |
46 | your programs slow and making them use a lot of memory. Best disable |
55 | integrate Coro into an event-based environment. |
47 | them when building perl, or aks your software vendor/distributor to do |
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48 | it for you). |
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49 | |
56 | |
50 | In this module, coroutines are defined as "callchain + lexical variables |
57 | In this module, a thread is defined as "callchain + lexical variables + |
51 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
58 | some package variables + C stack), that is, a thread has its own |
52 | callchain, its own set of lexicals and its own set of perls most |
59 | callchain, its own set of lexicals and its own set of perls most |
53 | important global variables (see Coro::State for more configuration). |
60 | important global variables (see Coro::State for more configuration and |
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61 | background info). |
54 | |
62 | |
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63 | See also the "SEE ALSO" section at the end of this document - the Coro |
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64 | module family is quite large. |
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65 | |
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66 | GLOBAL VARIABLES |
55 | $Coro::main |
67 | $Coro::main |
56 | This variable stores the coroutine object that represents the main |
68 | This variable stores the Coro object that represents the main |
57 | program. While you cna "ready" it and do most other things you can |
69 | program. While you cna "ready" it and do most other things you can |
58 | do to coroutines, it is mainly useful to compare again |
70 | do to coro, it is mainly useful to compare again $Coro::current, to |
59 | $Coro::current, to see whether you are running in the main program |
71 | see whether you are running in the main program or not. |
60 | or not. |
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61 | |
72 | |
62 | $Coro::current |
73 | $Coro::current |
63 | The coroutine object representing the current coroutine (the last |
74 | The Coro object representing the current coro (the last coro that |
64 | coroutine that the Coro scheduler switched to). The initial value is |
75 | the Coro scheduler switched to). The initial value is $Coro::main |
65 | $main (of course). |
76 | (of course). |
66 | |
77 | |
67 | This variable is strictly *read-only*. You can take copies of the |
78 | This variable is strictly *read-only*. You can take copies of the |
68 | value stored in it and use it as any other coroutine object, but you |
79 | value stored in it and use it as any other Coro object, but you must |
69 | must not otherwise modify the variable itself. |
80 | not otherwise modify the variable itself. |
70 | |
81 | |
71 | $Coro::idle |
82 | $Coro::idle |
72 | This variable is mainly useful to integrate Coro into event loops. |
83 | This variable is mainly useful to integrate Coro into event loops. |
73 | It is usually better to rely on Coro::AnyEvent or L"Coro::EV", as |
84 | It is usually better to rely on Coro::AnyEvent or Coro::EV, as this |
74 | this is pretty low-level functionality. |
85 | is pretty low-level functionality. |
75 | |
86 | |
76 | This variable stores a callback that is called whenever the |
87 | This variable stores either a Coro object or a callback. |
77 | scheduler finds no ready coroutines to run. The default |
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78 | implementation prints "FATAL: deadlock detected" and exits, because |
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79 | the program has no other way to continue. |
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80 | |
88 | |
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89 | If it is a callback, the it is called whenever the scheduler finds |
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90 | no ready coros to run. The default implementation prints "FATAL: |
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91 | deadlock detected" and exits, because the program has no other way |
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92 | to continue. |
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93 | |
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94 | If it is a coro object, then this object will be readied (without |
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95 | invoking any ready hooks, however) when the scheduler finds no other |
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96 | ready coros to run. |
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97 | |
81 | This hook is overwritten by modules such as "Coro::Timer" and |
98 | This hook is overwritten by modules such as "Coro::EV" and |
82 | "Coro::AnyEvent" to wait on an external event that hopefully wake up |
99 | "Coro::AnyEvent" to wait on an external event that hopefully wake up |
83 | a coroutine so the scheduler can run it. |
100 | a coro so the scheduler can run it. |
84 | |
101 | |
85 | Note that the callback *must not*, under any circumstances, block |
102 | Note that the callback *must not*, under any circumstances, block |
86 | the current coroutine. Normally, this is achieved by having an "idle |
103 | the current coro. Normally, this is achieved by having an "idle |
87 | coroutine" that calls the event loop and then blocks again, and then |
104 | coro" that calls the event loop and then blocks again, and then |
88 | readying that coroutine in the idle handler. |
105 | readying that coro in the idle handler, or by simply placing the |
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106 | idle coro in this variable. |
89 | |
107 | |
90 | See Coro::Event or Coro::AnyEvent for examples of using this |
108 | See Coro::Event or Coro::AnyEvent for examples of using this |
91 | technique. |
109 | technique. |
92 | |
110 | |
93 | Please note that if your callback recursively invokes perl (e.g. for |
111 | Please note that if your callback recursively invokes perl (e.g. for |
94 | event handlers), then it must be prepared to be called recursively |
112 | event handlers), then it must be prepared to be called recursively |
95 | itself. |
113 | itself. |
96 | |
114 | |
97 | SIMPLE COROUTINE CREATION |
115 | SIMPLE CORO CREATION |
98 | async { ... } [@args...] |
116 | async { ... } [@args...] |
99 | Create a new coroutine and return it's coroutine object (usually |
117 | Create a new coro and return its Coro object (usually unused). The |
100 | unused). The coroutine will be put into the ready queue, so it will |
118 | coro will be put into the ready queue, so it will start running |
101 | start running automatically on the next scheduler run. |
119 | automatically on the next scheduler run. |
102 | |
120 | |
103 | The first argument is a codeblock/closure that should be executed in |
121 | The first argument is a codeblock/closure that should be executed in |
104 | the coroutine. When it returns argument returns the coroutine is |
122 | the coro. When it returns argument returns the coro is automatically |
105 | automatically terminated. |
123 | terminated. |
106 | |
124 | |
107 | The remaining arguments are passed as arguments to the closure. |
125 | The remaining arguments are passed as arguments to the closure. |
108 | |
126 | |
109 | See the "Coro::State::new" constructor for info about the coroutine |
127 | See the "Coro::State::new" constructor for info about the coro |
110 | environment in which coroutines are executed. |
128 | environment in which coro are executed. |
111 | |
129 | |
112 | Calling "exit" in a coroutine will do the same as calling exit |
130 | Calling "exit" in a coro will do the same as calling exit outside |
113 | outside the coroutine. Likewise, when the coroutine dies, the |
131 | the coro. Likewise, when the coro dies, the program will exit, just |
114 | program will exit, just as it would in the main program. |
132 | as it would in the main program. |
115 | |
133 | |
116 | If you do not want that, you can provide a default "die" handler, or |
134 | If you do not want that, you can provide a default "die" handler, or |
117 | simply avoid dieing (by use of "eval"). |
135 | simply avoid dieing (by use of "eval"). |
118 | |
136 | |
119 | Example: Create a new coroutine that just prints its arguments. |
137 | Example: Create a new coro that just prints its arguments. |
120 | |
138 | |
121 | async { |
139 | async { |
122 | print "@_\n"; |
140 | print "@_\n"; |
123 | } 1,2,3,4; |
141 | } 1,2,3,4; |
124 | |
142 | |
125 | async_pool { ... } [@args...] |
143 | async_pool { ... } [@args...] |
126 | Similar to "async", but uses a coroutine pool, so you should not |
144 | Similar to "async", but uses a coro pool, so you should not call |
127 | call terminate or join on it (although you are allowed to), and you |
145 | terminate or join on it (although you are allowed to), and you get a |
128 | get a coroutine that might have executed other code already (which |
146 | coro that might have executed other code already (which can be good |
129 | can be good or bad :). |
147 | or bad :). |
130 | |
148 | |
131 | On the plus side, this function is faster than creating (and |
149 | On the plus side, this function is about twice as fast as creating |
132 | destroying) a completely new coroutine, so if you need a lot of |
150 | (and destroying) a completely new coro, so if you need a lot of |
133 | generic coroutines in quick successsion, use "async_pool", not |
151 | generic coros in quick successsion, use "async_pool", not "async". |
134 | "async". |
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135 | |
152 | |
136 | The code block is executed in an "eval" context and a warning will |
153 | The code block is executed in an "eval" context and a warning will |
137 | be issued in case of an exception instead of terminating the |
154 | be issued in case of an exception instead of terminating the |
138 | program, as "async" does. As the coroutine is being reused, stuff |
155 | program, as "async" does. As the coro is being reused, stuff like |
139 | like "on_destroy" will not work in the expected way, unless you call |
156 | "on_destroy" will not work in the expected way, unless you call |
140 | terminate or cancel, which somehow defeats the purpose of pooling |
157 | terminate or cancel, which somehow defeats the purpose of pooling |
141 | (but is fine in the exceptional case). |
158 | (but is fine in the exceptional case). |
142 | |
159 | |
143 | The priority will be reset to 0 after each run, tracing will be |
160 | The priority will be reset to 0 after each run, tracing will be |
144 | disabled, the description will be reset and the default output |
161 | disabled, the description will be reset and the default output |
145 | filehandle gets restored, so you can change all these. Otherwise the |
162 | filehandle gets restored, so you can change all these. Otherwise the |
146 | coroutine will be re-used "as-is": most notably if you change other |
163 | coro will be re-used "as-is": most notably if you change other |
147 | per-coroutine global stuff such as $/ you *must needs* to revert |
164 | per-coro global stuff such as $/ you *must needs* revert that |
148 | that change, which is most simply done by using local as in: " local |
165 | change, which is most simply done by using local as in: "local $/". |
149 | $/ ". |
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150 | |
166 | |
151 | The pool size is limited to 8 idle coroutines (this can be adjusted |
167 | The idle pool size is limited to 8 idle coros (this can be adjusted |
152 | by changing $Coro::POOL_SIZE), and there can be as many non-idle |
168 | by changing $Coro::POOL_SIZE), but there can be as many non-idle |
153 | coros as required. |
169 | coros as required. |
154 | |
170 | |
155 | If you are concerned about pooled coroutines growing a lot because a |
171 | If you are concerned about pooled coros growing a lot because a |
156 | single "async_pool" used a lot of stackspace you can e.g. |
172 | single "async_pool" used a lot of stackspace you can e.g. |
157 | "async_pool { terminate }" once per second or so to slowly replenish |
173 | "async_pool { terminate }" once per second or so to slowly replenish |
158 | the pool. In addition to that, when the stacks used by a handler |
174 | the pool. In addition to that, when the stacks used by a handler |
159 | grows larger than 16kb (adjustable via $Coro::POOL_RSS) it will also |
175 | grows larger than 32kb (adjustable via $Coro::POOL_RSS) it will also |
160 | be destroyed. |
176 | be destroyed. |
161 | |
177 | |
162 | STATIC METHODS |
178 | STATIC METHODS |
163 | Static methods are actually functions that operate on the current |
179 | Static methods are actually functions that implicitly operate on the |
164 | coroutine. |
180 | current coro. |
165 | |
181 | |
166 | schedule |
182 | schedule |
167 | Calls the scheduler. The scheduler will find the next coroutine that |
183 | Calls the scheduler. The scheduler will find the next coro that is |
168 | is to be run from the ready queue and switches to it. The next |
184 | to be run from the ready queue and switches to it. The next coro to |
169 | coroutine to be run is simply the one with the highest priority that |
185 | be run is simply the one with the highest priority that is longest |
170 | is longest in its ready queue. If there is no coroutine ready, it |
186 | in its ready queue. If there is no coro ready, it will clal the |
171 | will clal the $Coro::idle hook. |
187 | $Coro::idle hook. |
172 | |
188 | |
173 | Please note that the current coroutine will *not* be put into the |
189 | Please note that the current coro will *not* be put into the ready |
174 | ready queue, so calling this function usually means you will never |
190 | queue, so calling this function usually means you will never be |
175 | be called again unless something else (e.g. an event handler) calls |
191 | called again unless something else (e.g. an event handler) calls |
176 | "->ready", thus waking you up. |
192 | "->ready", thus waking you up. |
177 | |
193 | |
178 | This makes "schedule" *the* generic method to use to block the |
194 | This makes "schedule" *the* generic method to use to block the |
179 | current coroutine and wait for events: first you remember the |
195 | current coro and wait for events: first you remember the current |
180 | current coroutine in a variable, then arrange for some callback of |
196 | coro in a variable, then arrange for some callback of yours to call |
181 | yours to call "->ready" on that once some event happens, and last |
197 | "->ready" on that once some event happens, and last you call |
182 | you call "schedule" to put yourself to sleep. Note that a lot of |
198 | "schedule" to put yourself to sleep. Note that a lot of things can |
183 | things can wake your coroutine up, so you need to check whether the |
199 | wake your coro up, so you need to check whether the event indeed |
184 | event indeed happened, e.g. by storing the status in a variable. |
200 | happened, e.g. by storing the status in a variable. |
185 | |
201 | |
186 | The canonical way to wait on external events is this: |
202 | See HOW TO WAIT FOR A CALLBACK, below, for some ways to wait for |
187 | |
203 | callbacks. |
188 | { |
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189 | # remember current coroutine |
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190 | my $current = $Coro::current; |
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191 | |
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192 | # register a hypothetical event handler |
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193 | on_event_invoke sub { |
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194 | # wake up sleeping coroutine |
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195 | $current->ready; |
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196 | undef $current; |
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197 | }; |
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198 | |
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199 | # call schedule until event occurred. |
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200 | # in case we are woken up for other reasons |
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201 | # (current still defined), loop. |
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202 | Coro::schedule while $current; |
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203 | } |
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204 | |
204 | |
205 | cede |
205 | cede |
206 | "Cede" to other coroutines. This function puts the current coroutine |
206 | "Cede" to other coros. This function puts the current coro into the |
207 | into the ready queue and calls "schedule", which has the effect of |
207 | ready queue and calls "schedule", which has the effect of giving up |
208 | giving up the current "timeslice" to other coroutines of the same or |
208 | the current "timeslice" to other coros of the same or higher |
209 | higher priority. Once your coroutine gets its turn again it will |
209 | priority. Once your coro gets its turn again it will automatically |
210 | automatically be resumed. |
210 | be resumed. |
211 | |
211 | |
212 | This function is often called "yield" in other languages. |
212 | This function is often called "yield" in other languages. |
213 | |
213 | |
214 | Coro::cede_notself |
214 | Coro::cede_notself |
215 | Works like cede, but is not exported by default and will cede to |
215 | Works like cede, but is not exported by default and will cede to |
216 | *any* coroutine, regardless of priority. This is useful sometimes to |
216 | *any* coro, regardless of priority. This is useful sometimes to |
217 | ensure progress is made. |
217 | ensure progress is made. |
218 | |
218 | |
219 | terminate [arg...] |
219 | terminate [arg...] |
220 | Terminates the current coroutine with the given status values (see |
220 | Terminates the current coro with the given status values (see |
221 | cancel). |
221 | cancel). |
222 | |
222 | |
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223 | Coro::on_enter BLOCK, Coro::on_leave BLOCK |
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224 | These function install enter and leave winders in the current scope. |
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225 | The enter block will be executed when on_enter is called and |
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226 | whenever the current coro is re-entered by the scheduler, while the |
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227 | leave block is executed whenever the current coro is blocked by the |
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228 | scheduler, and also when the containing scope is exited (by whatever |
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229 | means, be it exit, die, last etc.). |
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230 | |
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231 | *Neither invoking the scheduler, nor exceptions, are allowed within |
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232 | those BLOCKs*. That means: do not even think about calling "die" |
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233 | without an eval, and do not even think of entering the scheduler in |
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234 | any way. |
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235 | |
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236 | Since both BLOCKs are tied to the current scope, they will |
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237 | automatically be removed when the current scope exits. |
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238 | |
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239 | These functions implement the same concept as "dynamic-wind" in |
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240 | scheme does, and are useful when you want to localise some resource |
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241 | to a specific coro. |
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242 | |
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243 | They slow down coro switching considerably for coros that use them |
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244 | (But coro switching is still reasonably fast if the handlers are |
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245 | fast). |
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246 | |
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247 | These functions are best understood by an example: The following |
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248 | function will change the current timezone to |
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249 | "Antarctica/South_Pole", which requires a call to "tzset", but by |
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250 | using "on_enter" and "on_leave", which remember/change the current |
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251 | timezone and restore the previous value, respectively, the timezone |
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252 | is only changes for the coro that installed those handlers. |
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253 | |
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254 | use POSIX qw(tzset); |
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255 | |
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256 | async { |
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257 | my $old_tz; # store outside TZ value here |
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258 | |
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259 | Coro::on_enter { |
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260 | $old_tz = $ENV{TZ}; # remember the old value |
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261 | |
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262 | $ENV{TZ} = "Antarctica/South_Pole"; |
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263 | tzset; # enable new value |
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264 | }; |
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265 | |
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266 | Coro::on_leave { |
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267 | $ENV{TZ} = $old_tz; |
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268 | tzset; # restore old value |
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269 | }; |
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270 | |
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271 | # at this place, the timezone is Antarctica/South_Pole, |
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272 | # without disturbing the TZ of any other coro. |
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273 | }; |
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274 | |
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275 | This can be used to localise about any resource (locale, uid, |
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276 | current working directory etc.) to a block, despite the existance of |
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277 | other coros. |
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278 | |
223 | killall |
279 | killall |
224 | Kills/terminates/cancels all coroutines except the currently running |
280 | Kills/terminates/cancels all coros except the currently running one. |
225 | one. This is useful after a fork, either in the child or the parent, |
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226 | as usually only one of them should inherit the running coroutines. |
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227 | |
281 | |
228 | Note that while this will try to free some of the main programs |
282 | Note that while this will try to free some of the main interpreter |
229 | resources, you cannot free all of them, so if a coroutine that is |
283 | resources if the calling coro isn't the main coro, but one cannot |
230 | not the main program calls this function, there will be some |
284 | free all of them, so if a coro that is not the main coro calls this |
231 | one-time resource leak. |
285 | function, there will be some one-time resource leak. |
232 | |
286 | |
233 | COROUTINE METHODS |
287 | CORO OBJECT METHODS |
234 | These are the methods you can call on coroutine objects (or to create |
288 | These are the methods you can call on coro objects (or to create them). |
235 | them). |
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236 | |
289 | |
237 | new Coro \&sub [, @args...] |
290 | new Coro \&sub [, @args...] |
238 | Create a new coroutine and return it. When the sub returns, the |
291 | Create a new coro and return it. When the sub returns, the coro |
239 | coroutine automatically terminates as if "terminate" with the |
292 | automatically terminates as if "terminate" with the returned values |
240 | returned values were called. To make the coroutine run you must |
293 | were called. To make the coro run you must first put it into the |
241 | first put it into the ready queue by calling the ready method. |
294 | ready queue by calling the ready method. |
242 | |
295 | |
243 | See "async" and "Coro::State::new" for additional info about the |
296 | See "async" and "Coro::State::new" for additional info about the |
244 | coroutine environment. |
297 | coro environment. |
245 | |
298 | |
246 | $success = $coroutine->ready |
299 | $success = $coro->ready |
247 | Put the given coroutine into the end of its ready queue (there is |
300 | Put the given coro into the end of its ready queue (there is one |
248 | one queue for each priority) and return true. If the coroutine is |
301 | queue for each priority) and return true. If the coro is already in |
249 | already in the ready queue, do nothing and return false. |
302 | the ready queue, do nothing and return false. |
250 | |
303 | |
251 | This ensures that the scheduler will resume this coroutine |
304 | This ensures that the scheduler will resume this coro automatically |
252 | automatically once all the coroutines of higher priority and all |
305 | once all the coro of higher priority and all coro of the same |
253 | coroutines of the same priority that were put into the ready queue |
306 | priority that were put into the ready queue earlier have been |
254 | earlier have been resumed. |
307 | resumed. |
255 | |
308 | |
256 | $is_ready = $coroutine->is_ready |
309 | $is_ready = $coro->is_ready |
257 | Return whether the coroutine is currently the ready queue or not, |
310 | Returns true iff the Coro object is in the ready queue. Unless the |
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311 | Coro object gets destroyed, it will eventually be scheduled by the |
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312 | scheduler. |
258 | |
313 | |
|
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314 | $is_running = $coro->is_running |
|
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315 | Returns true iff the Coro object is currently running. Only one Coro |
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316 | object can ever be in the running state (but it currently is |
|
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317 | possible to have multiple running Coro::States). |
|
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318 | |
|
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319 | $is_suspended = $coro->is_suspended |
|
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320 | Returns true iff this Coro object has been suspended. Suspended |
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321 | Coros will not ever be scheduled. |
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322 | |
259 | $coroutine->cancel (arg...) |
323 | $coro->cancel (arg...) |
260 | Terminates the given coroutine and makes it return the given |
324 | Terminates the given Coro and makes it return the given arguments as |
261 | arguments as status (default: the empty list). Never returns if the |
325 | status (default: the empty list). Never returns if the Coro is the |
262 | coroutine is the current coroutine. |
326 | current Coro. |
263 | |
327 | |
264 | $coroutine->join |
328 | $coro->schedule_to |
265 | Wait until the coroutine terminates and return any values given to |
329 | Puts the current coro to sleep (like "Coro::schedule"), but instead |
266 | the "terminate" or "cancel" functions. "join" can be called |
330 | of continuing with the next coro from the ready queue, always switch |
267 | concurrently from multiple coroutines, and all will be resumed and |
331 | to the given coro object (regardless of priority etc.). The |
268 | given the status return once the $coroutine terminates. |
332 | readyness state of that coro isn't changed. |
269 | |
333 | |
270 | $coroutine->on_destroy (\&cb) |
334 | This is an advanced method for special cases - I'd love to hear |
271 | Registers a callback that is called when this coroutine gets |
335 | about any uses for this one. |
272 | destroyed, but before it is joined. The callback gets passed the |
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273 | terminate arguments, if any, and *must not* die, under any |
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274 | circumstances. |
|
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275 | |
336 | |
276 | $oldprio = $coroutine->prio ($newprio) |
337 | $coro->cede_to |
277 | Sets (or gets, if the argument is missing) the priority of the |
338 | Like "schedule_to", but puts the current coro into the ready queue. |
278 | coroutine. Higher priority coroutines get run before lower priority |
339 | This has the effect of temporarily switching to the given coro, and |
279 | coroutines. Priorities are small signed integers (currently -4 .. |
340 | continuing some time later. |
280 | +3), that you can refer to using PRIO_xxx constants (use the import |
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281 | tag :prio to get then): |
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282 | |
341 | |
283 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
342 | This is an advanced method for special cases - I'd love to hear |
284 | 3 > 1 > 0 > -1 > -3 > -4 |
343 | about any uses for this one. |
285 | |
344 | |
286 | # set priority to HIGH |
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287 | current->prio(PRIO_HIGH); |
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288 | |
|
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289 | The idle coroutine ($Coro::idle) always has a lower priority than |
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290 | any existing coroutine. |
|
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291 | |
|
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292 | Changing the priority of the current coroutine will take effect |
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293 | immediately, but changing the priority of coroutines in the ready |
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294 | queue (but not running) will only take effect after the next |
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295 | schedule (of that coroutine). This is a bug that will be fixed in |
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296 | some future version. |
|
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297 | |
|
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298 | $newprio = $coroutine->nice ($change) |
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299 | Similar to "prio", but subtract the given value from the priority |
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300 | (i.e. higher values mean lower priority, just as in unix). |
|
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301 | |
|
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302 | $olddesc = $coroutine->desc ($newdesc) |
|
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303 | Sets (or gets in case the argument is missing) the description for |
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304 | this coroutine. This is just a free-form string you can associate |
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305 | with a coroutine. |
|
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306 | |
|
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307 | This method simply sets the "$coroutine->{desc}" member to the given |
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308 | string. You can modify this member directly if you wish. |
|
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309 | |
|
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310 | $coroutine->throw ([$scalar]) |
345 | $coro->throw ([$scalar]) |
311 | If $throw is specified and defined, it will be thrown as an |
346 | If $throw is specified and defined, it will be thrown as an |
312 | exception inside the coroutine at the next convinient point in time |
347 | exception inside the coro at the next convenient point in time. |
313 | (usually after it gains control at the next schedule/transfer/cede). |
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314 | Otherwise clears the exception object. |
348 | Otherwise clears the exception object. |
|
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349 | |
|
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350 | Coro will check for the exception each time a schedule-like-function |
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351 | returns, i.e. after each "schedule", "cede", |
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352 | "Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of |
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353 | these functions detect this case and return early in case an |
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354 | exception is pending. |
315 | |
355 | |
316 | The exception object will be thrown "as is" with the specified |
356 | The exception object will be thrown "as is" with the specified |
317 | scalar in $@, i.e. if it is a string, no line number or newline will |
357 | scalar in $@, i.e. if it is a string, no line number or newline will |
318 | be appended (unlike with "die"). |
358 | be appended (unlike with "die"). |
319 | |
359 | |
320 | This can be used as a softer means than "cancel" to ask a coroutine |
360 | This can be used as a softer means than "cancel" to ask a coro to |
321 | to end itself, although there is no guarentee that the exception |
361 | end itself, although there is no guarantee that the exception will |
322 | will lead to termination, and if the exception isn't caught it might |
362 | lead to termination, and if the exception isn't caught it might well |
323 | well end the whole program. |
363 | end the whole program. |
324 | |
364 | |
|
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365 | You might also think of "throw" as being the moral equivalent of |
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366 | "kill"ing a coro with a signal (in this case, a scalar). |
|
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367 | |
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368 | $coro->join |
|
|
369 | Wait until the coro terminates and return any values given to the |
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370 | "terminate" or "cancel" functions. "join" can be called concurrently |
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371 | from multiple coro, and all will be resumed and given the status |
|
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372 | return once the $coro terminates. |
|
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373 | |
|
|
374 | $coro->on_destroy (\&cb) |
|
|
375 | Registers a callback that is called when this coro gets destroyed, |
|
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376 | but before it is joined. The callback gets passed the terminate |
|
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377 | arguments, if any, and *must not* die, under any circumstances. |
|
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378 | |
|
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379 | $oldprio = $coro->prio ($newprio) |
|
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380 | Sets (or gets, if the argument is missing) the priority of the coro. |
|
|
381 | Higher priority coro get run before lower priority coro. Priorities |
|
|
382 | are small signed integers (currently -4 .. +3), that you can refer |
|
|
383 | to using PRIO_xxx constants (use the import tag :prio to get then): |
|
|
384 | |
|
|
385 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
|
|
386 | 3 > 1 > 0 > -1 > -3 > -4 |
|
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387 | |
|
|
388 | # set priority to HIGH |
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389 | current->prio (PRIO_HIGH); |
|
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390 | |
|
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391 | The idle coro ($Coro::idle) always has a lower priority than any |
|
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392 | existing coro. |
|
|
393 | |
|
|
394 | Changing the priority of the current coro will take effect |
|
|
395 | immediately, but changing the priority of coro in the ready queue |
|
|
396 | (but not running) will only take effect after the next schedule (of |
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397 | that coro). This is a bug that will be fixed in some future version. |
|
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398 | |
|
|
399 | $newprio = $coro->nice ($change) |
|
|
400 | Similar to "prio", but subtract the given value from the priority |
|
|
401 | (i.e. higher values mean lower priority, just as in unix). |
|
|
402 | |
|
|
403 | $olddesc = $coro->desc ($newdesc) |
|
|
404 | Sets (or gets in case the argument is missing) the description for |
|
|
405 | this coro. This is just a free-form string you can associate with a |
|
|
406 | coro. |
|
|
407 | |
|
|
408 | This method simply sets the "$coro->{desc}" member to the given |
|
|
409 | string. You can modify this member directly if you wish. |
|
|
410 | |
325 | GLOBAL FUNCTIONS |
411 | GLOBAL FUNCTIONS |
326 | Coro::nready |
412 | Coro::nready |
327 | Returns the number of coroutines that are currently in the ready |
413 | Returns the number of coro that are currently in the ready state, |
328 | state, i.e. that can be switched to by calling "schedule" directory |
414 | i.e. that can be switched to by calling "schedule" directory or |
329 | or indirectly. The value 0 means that the only runnable coroutine is |
415 | indirectly. The value 0 means that the only runnable coro is the |
330 | the currently running one, so "cede" would have no effect, and |
416 | currently running one, so "cede" would have no effect, and |
331 | "schedule" would cause a deadlock unless there is an idle handler |
417 | "schedule" would cause a deadlock unless there is an idle handler |
332 | that wakes up some coroutines. |
418 | that wakes up some coro. |
333 | |
419 | |
334 | my $guard = Coro::guard { ... } |
420 | my $guard = Coro::guard { ... } |
335 | This creates and returns a guard object. Nothing happens until the |
421 | This function still exists, but is deprecated. Please use the |
336 | object gets destroyed, in which case the codeblock given as argument |
422 | "Guard::guard" function instead. |
337 | will be executed. This is useful to free locks or other resources in |
|
|
338 | case of a runtime error or when the coroutine gets canceled, as in |
|
|
339 | both cases the guard block will be executed. The guard object |
|
|
340 | supports only one method, "->cancel", which will keep the codeblock |
|
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341 | from being executed. |
|
|
342 | |
|
|
343 | Example: set some flag and clear it again when the coroutine gets |
|
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344 | canceled or the function returns: |
|
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345 | |
|
|
346 | sub do_something { |
|
|
347 | my $guard = Coro::guard { $busy = 0 }; |
|
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348 | $busy = 1; |
|
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349 | |
|
|
350 | # do something that requires $busy to be true |
|
|
351 | } |
|
|
352 | |
423 | |
353 | unblock_sub { ... } |
424 | unblock_sub { ... } |
354 | This utility function takes a BLOCK or code reference and "unblocks" |
425 | This utility function takes a BLOCK or code reference and "unblocks" |
355 | it, returning a new coderef. Unblocking means that calling the new |
426 | it, returning a new coderef. Unblocking means that calling the new |
356 | coderef will return immediately without blocking, returning nothing, |
427 | coderef will return immediately without blocking, returning nothing, |
357 | while the original code ref will be called (with parameters) from |
428 | while the original code ref will be called (with parameters) from |
358 | within another coroutine. |
429 | within another coro. |
359 | |
430 | |
360 | The reason this function exists is that many event libraries (such |
431 | The reason this function exists is that many event libraries (such |
361 | as the venerable Event module) are not coroutine-safe (a weaker form |
432 | as the venerable Event module) are not thread-safe (a weaker form of |
362 | of thread-safety). This means you must not block within event |
433 | reentrancy). This means you must not block within event callbacks, |
363 | callbacks, otherwise you might suffer from crashes or worse. The |
434 | otherwise you might suffer from crashes or worse. The only event |
364 | only event library currently known that is safe to use without |
435 | library currently known that is safe to use without "unblock_sub" is |
365 | "unblock_sub" is EV. |
436 | EV. |
366 | |
437 | |
367 | This function allows your callbacks to block by executing them in |
438 | This function allows your callbacks to block by executing them in |
368 | another coroutine where it is safe to block. One example where |
439 | another coro where it is safe to block. One example where blocking |
369 | blocking is handy is when you use the Coro::AIO functions to save |
440 | is handy is when you use the Coro::AIO functions to save results to |
370 | results to disk, for example. |
441 | disk, for example. |
371 | |
442 | |
372 | In short: simply use "unblock_sub { ... }" instead of "sub { ... }" |
443 | In short: simply use "unblock_sub { ... }" instead of "sub { ... }" |
373 | when creating event callbacks that want to block. |
444 | when creating event callbacks that want to block. |
374 | |
445 | |
375 | If your handler does not plan to block (e.g. simply sends a message |
446 | If your handler does not plan to block (e.g. simply sends a message |
376 | to another coroutine, or puts some other coroutine into the ready |
447 | to another coro, or puts some other coro into the ready queue), |
377 | queue), there is no reason to use "unblock_sub". |
448 | there is no reason to use "unblock_sub". |
378 | |
449 | |
379 | Note that you also need to use "unblock_sub" for any other callbacks |
450 | Note that you also need to use "unblock_sub" for any other callbacks |
380 | that are indirectly executed by any C-based event loop. For example, |
451 | that are indirectly executed by any C-based event loop. For example, |
381 | when you use a module that uses AnyEvent (and you use |
452 | when you use a module that uses AnyEvent (and you use |
382 | Coro::AnyEvent) and it provides callbacks that are the result of |
453 | Coro::AnyEvent) and it provides callbacks that are the result of |
383 | some event callback, then you must not block either, or use |
454 | some event callback, then you must not block either, or use |
384 | "unblock_sub". |
455 | "unblock_sub". |
385 | |
456 | |
|
|
457 | $cb = Coro::rouse_cb |
|
|
458 | Create and return a "rouse callback". That's a code reference that, |
|
|
459 | when called, will remember a copy of its arguments and notify the |
|
|
460 | owner coro of the callback. |
|
|
461 | |
|
|
462 | See the next function. |
|
|
463 | |
|
|
464 | @args = Coro::rouse_wait [$cb] |
|
|
465 | Wait for the specified rouse callback (or the last one that was |
|
|
466 | created in this coro). |
|
|
467 | |
|
|
468 | As soon as the callback is invoked (or when the callback was invoked |
|
|
469 | before "rouse_wait"), it will return the arguments originally passed |
|
|
470 | to the rouse callback. |
|
|
471 | |
|
|
472 | See the section HOW TO WAIT FOR A CALLBACK for an actual usage |
|
|
473 | example. |
|
|
474 | |
|
|
475 | HOW TO WAIT FOR A CALLBACK |
|
|
476 | It is very common for a coro to wait for some callback to be called. |
|
|
477 | This occurs naturally when you use coro in an otherwise event-based |
|
|
478 | program, or when you use event-based libraries. |
|
|
479 | |
|
|
480 | These typically register a callback for some event, and call that |
|
|
481 | callback when the event occured. In a coro, however, you typically want |
|
|
482 | to just wait for the event, simplyifying things. |
|
|
483 | |
|
|
484 | For example "AnyEvent->child" registers a callback to be called when a |
|
|
485 | specific child has exited: |
|
|
486 | |
|
|
487 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
488 | |
|
|
489 | But from within a coro, you often just want to write this: |
|
|
490 | |
|
|
491 | my $status = wait_for_child $pid; |
|
|
492 | |
|
|
493 | Coro offers two functions specifically designed to make this easy, |
|
|
494 | "Coro::rouse_cb" and "Coro::rouse_wait". |
|
|
495 | |
|
|
496 | The first function, "rouse_cb", generates and returns a callback that, |
|
|
497 | when invoked, will save its arguments and notify the coro that created |
|
|
498 | the callback. |
|
|
499 | |
|
|
500 | The second function, "rouse_wait", waits for the callback to be called |
|
|
501 | (by calling "schedule" to go to sleep) and returns the arguments |
|
|
502 | originally passed to the callback. |
|
|
503 | |
|
|
504 | Using these functions, it becomes easy to write the "wait_for_child" |
|
|
505 | function mentioned above: |
|
|
506 | |
|
|
507 | sub wait_for_child($) { |
|
|
508 | my ($pid) = @_; |
|
|
509 | |
|
|
510 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
511 | |
|
|
512 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
513 | $rstatus |
|
|
514 | } |
|
|
515 | |
|
|
516 | In the case where "rouse_cb" and "rouse_wait" are not flexible enough, |
|
|
517 | you can roll your own, using "schedule": |
|
|
518 | |
|
|
519 | sub wait_for_child($) { |
|
|
520 | my ($pid) = @_; |
|
|
521 | |
|
|
522 | # store the current coro in $current, |
|
|
523 | # and provide result variables for the closure passed to ->child |
|
|
524 | my $current = $Coro::current; |
|
|
525 | my ($done, $rstatus); |
|
|
526 | |
|
|
527 | # pass a closure to ->child |
|
|
528 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
529 | $rstatus = $_[1]; # remember rstatus |
|
|
530 | $done = 1; # mark $rstatus as valud |
|
|
531 | }); |
|
|
532 | |
|
|
533 | # wait until the closure has been called |
|
|
534 | schedule while !$done; |
|
|
535 | |
|
|
536 | $rstatus |
|
|
537 | } |
|
|
538 | |
386 | BUGS/LIMITATIONS |
539 | BUGS/LIMITATIONS |
|
|
540 | fork with pthread backend |
|
|
541 | When Coro is compiled using the pthread backend (which isn't |
|
|
542 | recommended but required on many BSDs as their libcs are completely |
|
|
543 | broken), then coro will not survive a fork. There is no known |
|
|
544 | workaround except to fix your libc and use a saner backend. |
|
|
545 | |
|
|
546 | perl process emulation ("threads") |
387 | This module is not perl-pseudo-thread-safe. You should only ever use |
547 | This module is not perl-pseudo-thread-safe. You should only ever use |
388 | this module from the same thread (this requirement might be removed in |
548 | this module from the first thread (this requirement might be removed |
389 | the future to allow per-thread schedulers, but Coro::State does not yet |
549 | in the future to allow per-thread schedulers, but Coro::State does |
390 | allow this). I recommend disabling thread support and using processes, |
550 | not yet allow this). I recommend disabling thread support and using |
391 | as this is much faster and uses less memory. |
551 | processes, as having the windows process emulation enabled under |
|
|
552 | unix roughly halves perl performance, even when not used. |
|
|
553 | |
|
|
554 | coro switching is not signal safe |
|
|
555 | You must not switch to another coro from within a signal handler |
|
|
556 | (only relevant with %SIG - most event libraries provide safe |
|
|
557 | signals). |
|
|
558 | |
|
|
559 | That means you *MUST NOT* call any function that might "block" the |
|
|
560 | current coro - "cede", "schedule" "Coro::Semaphore->down" or |
|
|
561 | anything that calls those. Everything else, including calling |
|
|
562 | "ready", works. |
392 | |
563 | |
393 | SEE ALSO |
564 | SEE ALSO |
394 | Event-Loop integration: Coro::AnyEvent, Coro::EV, Coro::Event. |
565 | Event-Loop integration: Coro::AnyEvent, Coro::EV, Coro::Event. |
395 | |
566 | |
396 | Debugging: Coro::Debug. |
567 | Debugging: Coro::Debug. |
397 | |
568 | |
398 | Support/Utility: Coro::Specific, Coro::Util. |
569 | Support/Utility: Coro::Specific, Coro::Util. |
399 | |
570 | |
400 | Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore, |
571 | Locking and IPC: Coro::Signal, Coro::Channel, Coro::Semaphore, |
401 | Coro::SemaphoreSet, Coro::RWLock. |
572 | Coro::SemaphoreSet, Coro::RWLock. |
402 | |
573 | |
403 | IO/Timers: Coro::Timer, Coro::Handle, Coro::Socket, Coro::AIO. |
574 | I/O and Timers: Coro::Timer, Coro::Handle, Coro::Socket, Coro::AIO. |
404 | |
575 | |
405 | Compatibility: Coro::LWP, Coro::BDB, Coro::Storable, Coro::Select. |
576 | Compatibility with other modules: Coro::LWP (but see also AnyEvent::HTTP |
|
|
577 | for a better-working alternative), Coro::BDB, Coro::Storable, |
|
|
578 | Coro::Select. |
406 | |
579 | |
407 | XS API: Coro::MakeMaker. |
580 | XS API: Coro::MakeMaker. |
408 | |
581 | |
409 | Low level Configuration, Coroutine Environment: Coro::State. |
582 | Low level Configuration, Thread Environment, Continuations: Coro::State. |
410 | |
583 | |
411 | AUTHOR |
584 | AUTHOR |
412 | Marc Lehmann <schmorp@schmorp.de> |
585 | Marc Lehmann <schmorp@schmorp.de> |
413 | http://home.schmorp.de/ |
586 | http://home.schmorp.de/ |
414 | |
587 | |