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Revision 1.21 by root, Mon Dec 15 20:52:04 2008 UTC

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 {
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	};
10		13	print "1\n";
11	# alternatively create an async process like this:	14	cede; # yield to coro
12		15	print "3\n";
13	sub some_func : Coro {	16	cede; # and again
14	# some more async code
15	}	17
16		18	# use locking
17	cede;	19	use Coro::Semaphore;
		20	my $lock = new Coro::Semaphore;
		21	my $locked;
		22
		23	$lock->down;
		24	$locked = 1;
		25	$lock->up;
18		26
19	DESCRIPTION	27	DESCRIPTION
20	This module collection manages coroutines. Coroutines are similar to	28	For a tutorial-style introduction, please read the Coro::Intro manpage.
21	threads but don't run in parallel.	29	This manpage mainly contains reference information.
22		30
		31	This module collection manages continuations in general, most often in
		32	the form of cooperative threads (also called coros, or simply "coro" in
		33	the documentation). They are similar to kernel threads but don't (in
		34	general) run in parallel at the same time even on SMP machines. The
		35	specific flavor of thread offered by this module also guarantees you
		36	that it will not switch between threads unless necessary, at
		37	easily-identified points in your program, so locking and parallel access
		38	are rarely an issue, making thread programming much safer and easier
		39	than using other thread models.
		40
		41	Unlike the so-called "Perl threads" (which are not actually real threads
		42	but only the windows process emulation ported to unix, and as such act
		43	as processes), Coro provides a full shared address space, which makes
		44	communication between threads very easy. And Coro's threads are fast,
		45	too: disabling the Windows process emulation code in your perl and using
		46	Coro can easily result in a two to four times speed increase for your
		47	programs. A parallel matrix multiplication benchmark runs over 300 times
		48	faster on a single core than perl's pseudo-threads on a quad core using
		49	all four cores.
		50
		51	Coro achieves that by supporting multiple running interpreters that
		52	share data, which is especially useful to code pseudo-parallel processes
		53	and for event-based programming, such as multiple HTTP-GET requests
		54	running concurrently. See Coro::AnyEvent to learn more on how to
		55	integrate Coro into an event-based environment.
		56
23	In this module, coroutines are defined as "callchain + lexical variables	57	In this module, a thread is defined as "callchain + lexical variables +
24	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	58	some package variables + C stack), that is, a thread has its own
25	callchain, it's own set of lexicals and it's own set of perl's most	59	callchain, its own set of lexicals and its own set of perls most
26	important global variables.	60	important global variables (see Coro::State for more configuration and
		61	background info).
27		62
		63	See also the "SEE ALSO" section at the end of this document - the Coro
		64	module family is quite large.
		65
		66	GLOBAL VARIABLES
28	$main	67	$Coro::main
29	This coroutine represents the main program.	68	This variable stores the Coro object that represents the main
		69	program. While you cna "ready" it and do most other things you can
		70	do to coro, it is mainly useful to compare again $Coro::current, to
		71	see whether you are running in the main program or not.
30		72
31	$current (or as function: current)	73	$Coro::current
32	The current coroutine (the last coroutine switched to). The initial	74	The Coro object representing the current coro (the last coro that
33	value is $main (of course).	75	the Coro scheduler switched to). The initial value is $Coro::main
		76	(of course).
34		77
		78	This variable is strictly read-only. You can take copies of the
		79	value stored in it and use it as any other Coro object, but you must
		80	not otherwise modify the variable itself.
		81
35	$idle	82	$Coro::idle
36	The coroutine to switch to when no other coroutine is running. The	83	This variable is mainly useful to integrate Coro into event loops.
37	default implementation prints "FATAL: deadlock detected" and exits.	84	It is usually better to rely on Coro::AnyEvent or Coro::EV, as this
		85	is pretty low-level functionality.
38		86
39	STATIC METHODS	87	This variable stores either a Coro object or a callback.
40	Static methods are actually functions that operate on the current
41	process only.
42		88
		89	If it is a callback, the it is called whenever the scheduler finds
		90	no ready coros to run. The default implementation prints "FATAL:
		91	deadlock detected" and exits, because the program has no other way
		92	to continue.
		93
		94	If it is a coro object, then this object will be readied (without
		95	invoking any ready hooks, however) when the scheduler finds no other
		96	ready coros to run.
		97
		98	This hook is overwritten by modules such as "Coro::EV" and
		99	"Coro::AnyEvent" to wait on an external event that hopefully wake up
		100	a coro so the scheduler can run it.
		101
		102	Note that the callback must not, under any circumstances, block
		103	the current coro. Normally, this is achieved by having an "idle
		104	coro" that calls the event loop and then blocks again, and then
		105	readying that coro in the idle handler, or by simply placing the
		106	idle coro in this variable.
		107
		108	See Coro::Event or Coro::AnyEvent for examples of using this
		109	technique.
		110
		111	Please note that if your callback recursively invokes perl (e.g. for
		112	event handlers), then it must be prepared to be called recursively
		113	itself.
		114
		115	SIMPLE CORO CREATION
43	async { ... } [@args...]	116	async { ... } [@args...]
44	Create a new asynchronous process and return it's process object	117	Create a new coro and return its Coro object (usually unused). The
45	(usually unused). When the sub returns the new process is	118	coro will be put into the ready queue, so it will start running
46	automatically terminated.	119	automatically on the next scheduler run.
47		120
48	When the coroutine dies, the program will exit, just as in the main	121	The first argument is a codeblock/closure that should be executed in
49	program.	122	the coro. When it returns argument returns the coro is automatically
		123	terminated.
50		124
		125	The remaining arguments are passed as arguments to the closure.
		126
		127	See the "Coro::State::new" constructor for info about the coro
		128	environment in which coro are executed.
		129
		130	Calling "exit" in a coro will do the same as calling exit outside
		131	the coro. Likewise, when the coro dies, the program will exit, just
		132	as it would in the main program.
		133
		134	If you do not want that, you can provide a default "die" handler, or
		135	simply avoid dieing (by use of "eval").
		136
51	# create a new coroutine that just prints its arguments	137	Example: Create a new coro that just prints its arguments.
		138
52	async {	139	async {
53	print "@_\n";	140	print "@_\n";
54	} 1,2,3,4;	141	} 1,2,3,4;
55		142
		143	async_pool { ... } [@args...]
		144	Similar to "async", but uses a coro pool, so you should not call
		145	terminate or join on it (although you are allowed to), and you get a
		146	coro that might have executed other code already (which can be good
		147	or bad :).
		148
		149	On the plus side, this function is about twice as fast as creating
		150	(and destroying) a completely new coro, so if you need a lot of
		151	generic coros in quick successsion, use "async_pool", not "async".
		152
		153	The code block is executed in an "eval" context and a warning will
		154	be issued in case of an exception instead of terminating the
		155	program, as "async" does. As the coro is being reused, stuff like
		156	"on_destroy" will not work in the expected way, unless you call
		157	terminate or cancel, which somehow defeats the purpose of pooling
		158	(but is fine in the exceptional case).
		159
		160	The priority will be reset to 0 after each run, tracing will be
		161	disabled, the description will be reset and the default output
		162	filehandle gets restored, so you can change all these. Otherwise the
		163	coro will be re-used "as-is": most notably if you change other
		164	per-coro global stuff such as $/ you must needs revert that
		165	change, which is most simply done by using local as in: "local $/".
		166
		167	The idle pool size is limited to 8 idle coros (this can be adjusted
		168	by changing $Coro::POOL_SIZE), but there can be as many non-idle
		169	coros as required.
		170
		171	If you are concerned about pooled coros growing a lot because a
		172	single "async_pool" used a lot of stackspace you can e.g.
		173	"async_pool { terminate }" once per second or so to slowly replenish
		174	the pool. In addition to that, when the stacks used by a handler
		175	grows larger than 32kb (adjustable via $Coro::POOL_RSS) it will also
		176	be destroyed.
		177
		178	STATIC METHODS
		179	Static methods are actually functions that implicitly operate on the
		180	current coro.
		181
56	schedule	182	schedule
57	Calls the scheduler. Please note that the current process will not	183	Calls the scheduler. The scheduler will find the next coro that is
58	be put into the ready queue, so calling this function usually means	184	to be run from the ready queue and switches to it. The next coro to
59	you will never be called again.	185	be run is simply the one with the highest priority that is longest
		186	in its ready queue. If there is no coro ready, it will clal the
		187	$Coro::idle hook.
		188
		189	Please note that the current coro will not be put into the ready
		190	queue, so calling this function usually means you will never be
		191	called again unless something else (e.g. an event handler) calls
		192	"->ready", thus waking you up.
		193
		194	This makes "schedule" the generic method to use to block the
		195	current coro and wait for events: first you remember the current
		196	coro in a variable, then arrange for some callback of yours to call
		197	"->ready" on that once some event happens, and last you call
		198	"schedule" to put yourself to sleep. Note that a lot of things can
		199	wake your coro up, so you need to check whether the event indeed
		200	happened, e.g. by storing the status in a variable.
		201
		202	See HOW TO WAIT FOR A CALLBACK, below, for some ways to wait for
		203	callbacks.
60		204
61	cede	205	cede
62	"Cede" to other processes. This function puts the current process	206	"Cede" to other coros. This function puts the current coro into the
63	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
64	giving up the current "timeslice" to other coroutines of the same or	208	the current "timeslice" to other coros of the same or higher
65	higher priority.	209	priority. Once your coro gets its turn again it will automatically
		210	be resumed.
		211
		212	This function is often called "yield" in other languages.
		213
		214	Coro::cede_notself
		215	Works like cede, but is not exported by default and will cede to
		216	any coro, regardless of priority. This is useful sometimes to
		217	ensure progress is made.
66		218
67	terminate [arg...]	219	terminate [arg...]
68	Terminates the current process with the given status values (see	220	Terminates the current coro with the given status values (see
69	cancel).	221	cancel).
70		222
71	# dynamic methods	223	Coro::on_enter BLOCK, Coro::on_leave BLOCK
		224	These function install enter and leave winders in the current scope.
		225	The enter block will be executed when on_enter is called and
		226	whenever the current coro is re-entered by the scheduler, while the
		227	leave block is executed whenever the current coro is blocked by the
		228	scheduler, and also when the containing scope is exited (by whatever
		229	means, be it exit, die, last etc.).
72		230
73	PROCESS METHODS	231	*Neither invoking the scheduler, nor exceptions, are allowed within
		232	those BLOCKs*. That means: do not even think about calling "die"
		233	without an eval, and do not even think of entering the scheduler in
		234	any way.
		235
		236	Since both BLOCKs are tied to the current scope, they will
		237	automatically be removed when the current scope exits.
		238
		239	These functions implement the same concept as "dynamic-wind" in
		240	scheme does, and are useful when you want to localise some resource
		241	to a specific coro.
		242
		243	They slow down coro switching considerably for coros that use them
		244	(But coro switching is still reasonably fast if the handlers are
		245	fast).
		246
		247	These functions are best understood by an example: The following
		248	function will change the current timezone to
		249	"Antarctica/South_Pole", which requires a call to "tzset", but by
		250	using "on_enter" and "on_leave", which remember/change the current
		251	timezone and restore the previous value, respectively, the timezone
		252	is only changes for the coro that installed those handlers.
		253
		254	use POSIX qw(tzset);
		255
		256	async {
		257	my $old_tz; # store outside TZ value here
		258
		259	Coro::on_enter {
		260	$old_tz = $ENV{TZ}; # remember the old value
		261
		262	$ENV{TZ} = "Antarctica/South_Pole";
		263	tzset; # enable new value
		264	};
		265
		266	Coro::on_leave {
		267	$ENV{TZ} = $old_tz;
		268	tzset; # restore old value
		269	};
		270
		271	# at this place, the timezone is Antarctica/South_Pole,
		272	# without disturbing the TZ of any other coro.
		273	};
		274
		275	This can be used to localise about any resource (locale, uid,
		276	current working directory etc.) to a block, despite the existance of
		277	other coros.
		278
		279	killall
		280	Kills/terminates/cancels all coros except the currently running one.
		281
		282	Note that while this will try to free some of the main interpreter
		283	resources if the calling coro isn't the main coro, but one cannot
		284	free all of them, so if a coro that is not the main coro calls this
		285	function, there will be some one-time resource leak.
		286
		287	CORO OBJECT METHODS
74	These are the methods you can call on process objects.	288	These are the methods you can call on coro objects (or to create them).
75		289
76	new Coro \&sub [, @args...]	290	new Coro \&sub [, @args...]
77	Create a new process and return it. When the sub returns the process	291	Create a new coro and return it. When the sub returns, the coro
78	automatically terminates as if "terminate" with the returned values	292	automatically terminates as if "terminate" with the returned values
79	were called. To make the process run you must first put it into the	293	were called. To make the coro run you must first put it into the
80	ready queue by calling the ready method.	294	ready queue by calling the ready method.
81		295
82	$process->ready	296	See "async" and "Coro::State::new" for additional info about the
83	Put the given process into the ready queue.	297	coro environment.
84		298
		299	$success = $coro->ready
		300	Put the given coro into the end of its ready queue (there is one
		301	queue for each priority) and return true. If the coro is already in
		302	the ready queue, do nothing and return false.
		303
		304	This ensures that the scheduler will resume this coro automatically
		305	once all the coro of higher priority and all coro of the same
		306	priority that were put into the ready queue earlier have been
		307	resumed.
		308
		309	$is_ready = $coro->is_ready
		310	Returns true iff the Coro object is in the ready queue. Unless the
		311	Coro object gets destroyed, it will eventually be scheduled by the
		312	scheduler.
		313
		314	$is_running = $coro->is_running
		315	Returns true iff the Coro object is currently running. Only one Coro
		316	object can ever be in the running state (but it currently is
		317	possible to have multiple running Coro::States).
		318
		319	$is_suspended = $coro->is_suspended
		320	Returns true iff this Coro object has been suspended. Suspended
		321	Coros will not ever be scheduled.
		322
85	$process->cancel (arg...)	323	$coro->cancel (arg...)
86	Terminates the given process and makes it return the given arguments	324	Terminates the given Coro and makes it return the given arguments as
87	as status (default: the empty list).	325	status (default: the empty list). Never returns if the Coro is the
		326	current Coro.
88		327
		328	$coro->schedule_to
		329	Puts the current coro to sleep (like "Coro::schedule"), but instead
		330	of continuing with the next coro from the ready queue, always switch
		331	to the given coro object (regardless of priority etc.). The
		332	readyness state of that coro isn't changed.
		333
		334	This is an advanced method for special cases - I'd love to hear
		335	about any uses for this one.
		336
		337	$coro->cede_to
		338	Like "schedule_to", but puts the current coro into the ready queue.
		339	This has the effect of temporarily switching to the given coro, and
		340	continuing some time later.
		341
		342	This is an advanced method for special cases - I'd love to hear
		343	about any uses for this one.
		344
		345	$coro->throw ([$scalar])
		346	If $throw is specified and defined, it will be thrown as an
		347	exception inside the coro at the next convenient point in time.
		348	Otherwise clears the exception object.
		349
		350	Coro will check for the exception each time a schedule-like-function
		351	returns, i.e. after each "schedule", "cede",
		352	"Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of
		353	these functions detect this case and return early in case an
		354	exception is pending.
		355
		356	The exception object will be thrown "as is" with the specified
		357	scalar in $@, i.e. if it is a string, no line number or newline will
		358	be appended (unlike with "die").
		359
		360	This can be used as a softer means than "cancel" to ask a coro to
		361	end itself, although there is no guarantee that the exception will
		362	lead to termination, and if the exception isn't caught it might well
		363	end the whole program.
		364
		365	You might also think of "throw" as being the moral equivalent of
		366	"kill"ing a coro with a signal (in this case, a scalar).
		367
89	$process->join	368	$coro->join
90	Wait until the coroutine terminates and return any values given to	369	Wait until the coro terminates and return any values given to the
91	the "terminate" or "cancel" functions. "join" can be called multiple	370	"terminate" or "cancel" functions. "join" can be called concurrently
92	times from multiple processes.	371	from multiple coro, and all will be resumed and given the status
		372	return once the $coro terminates.
93		373
		374	$coro->on_destroy (\&cb)
		375	Registers a callback that is called when this coro gets destroyed,
		376	but before it is joined. The callback gets passed the terminate
		377	arguments, if any, and must not die, under any circumstances.
		378
94	$oldprio = $process->prio($newprio)	379	$oldprio = $coro->prio ($newprio)
95	Sets (or gets, if the argument is missing) the priority of the	380	Sets (or gets, if the argument is missing) the priority of the coro.
96	process. Higher priority processes get run before lower priority	381	Higher priority coro get run before lower priority coro. Priorities
97	processes. Priorities are small signed integers (currently -4 ..	382	are small signed integers (currently -4 .. +3), that you can refer
98	+3), that you can refer to using PRIO_xxx constants (use the import	383	to using PRIO_xxx constants (use the import tag :prio to get then):
99	tag :prio to get then):
100		384
101	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	385	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
102	3 > 1 > 0 > -1 > -3 > -4	386	3 > 1 > 0 > -1 > -3 > -4
103		387
104	# set priority to HIGH	388	# set priority to HIGH
105	current->prio(PRIO_HIGH);	389	current->prio (PRIO_HIGH);
106		390
107	The idle coroutine ($Coro::idle) always has a lower priority than	391	The idle coro ($Coro::idle) always has a lower priority than any
108	any existing coroutine.	392	existing coro.
109		393
110	Changing the priority of the current process will take effect	394	Changing the priority of the current coro will take effect
111	immediately, but changing the priority of processes in the ready	395	immediately, but changing the priority of coro in the ready queue
112	queue (but not running) will only take effect after the next	396	(but not running) will only take effect after the next schedule (of
113	schedule (of that process). This is a bug that will be fixed in some	397	that coro). This is a bug that will be fixed in some future version.
114	future version.
115		398
116	$newprio = $process->nice($change)	399	$newprio = $coro->nice ($change)
117	Similar to "prio", but subtract the given value from the priority	400	Similar to "prio", but subtract the given value from the priority
118	(i.e. higher values mean lower priority, just as in unix).	401	(i.e. higher values mean lower priority, just as in unix).
119		402
120	$olddesc = $process->desc($newdesc)	403	$olddesc = $coro->desc ($newdesc)
121	Sets (or gets in case the argument is missing) the description for	404	Sets (or gets in case the argument is missing) the description for
122	this process. This is just a free-form string you can associate with	405	this coro. This is just a free-form string you can associate with a
123	a process.	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
		411	GLOBAL FUNCTIONS
		412	Coro::nready
		413	Returns the number of coro that are currently in the ready state,
		414	i.e. that can be switched to by calling "schedule" directory or
		415	indirectly. The value 0 means that the only runnable coro is the
		416	currently running one, so "cede" would have no effect, and
		417	"schedule" would cause a deadlock unless there is an idle handler
		418	that wakes up some coro.
		419
		420	my $guard = Coro::guard { ... }
		421	This function still exists, but is deprecated. Please use the
		422	"Guard::guard" function instead.
		423
		424	unblock_sub { ... }
		425	This utility function takes a BLOCK or code reference and "unblocks"
		426	it, returning a new coderef. Unblocking means that calling the new
		427	coderef will return immediately without blocking, returning nothing,
		428	while the original code ref will be called (with parameters) from
		429	within another coro.
		430
		431	The reason this function exists is that many event libraries (such
		432	as the venerable Event module) are not thread-safe (a weaker form of
		433	reentrancy). This means you must not block within event callbacks,
		434	otherwise you might suffer from crashes or worse. The only event
		435	library currently known that is safe to use without "unblock_sub" is
		436	EV.
		437
		438	This function allows your callbacks to block by executing them in
		439	another coro where it is safe to block. One example where blocking
		440	is handy is when you use the Coro::AIO functions to save results to
		441	disk, for example.
		442
		443	In short: simply use "unblock_sub { ... }" instead of "sub { ... }"
		444	when creating event callbacks that want to block.
		445
		446	If your handler does not plan to block (e.g. simply sends a message
		447	to another coro, or puts some other coro into the ready queue),
		448	there is no reason to use "unblock_sub".
		449
		450	Note that you also need to use "unblock_sub" for any other callbacks
		451	that are indirectly executed by any C-based event loop. For example,
		452	when you use a module that uses AnyEvent (and you use
		453	Coro::AnyEvent) and it provides callbacks that are the result of
		454	some event callback, then you must not block either, or use
		455	"unblock_sub".
		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	}
124		538
125	BUGS/LIMITATIONS	539	BUGS/LIMITATIONS
126	- you must make very sure that no coro is still active on global	540	fork with pthread backend
127	destruction. very bad things might happen otherwise (usually segfaults).	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.
128		545
		546	perl process emulation ("threads")
129	- this module is not thread-safe. You should only ever use this module	547	This module is not perl-pseudo-thread-safe. You should only ever use
130	from the same thread (this requirement might be losened in the future	548	this module from the first thread (this requirement might be removed
131	to allow per-thread schedulers, but Coro::State does not yet allow	549	in the future to allow per-thread schedulers, but Coro::State does
132	this).	550	not yet allow this). I recommend disabling thread support and using
		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.
133		563
134	SEE ALSO	564	SEE ALSO
		565	Event-Loop integration: Coro::AnyEvent, Coro::EV, Coro::Event.
		566
		567	Debugging: Coro::Debug.
		568
135	Support/Utility: Coro::Cont, Coro::Specific, Coro::State, Coro::Util.	569	Support/Utility: Coro::Specific, Coro::Util.
136		570
137	Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore,	571	Locking and IPC: Coro::Signal, Coro::Channel, Coro::Semaphore,
138	Coro::SemaphoreSet, Coro::RWLock.	572	Coro::SemaphoreSet, Coro::RWLock.
139		573
140	Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket,	574	I/O and Timers: Coro::Timer, Coro::Handle, Coro::Socket, Coro::AIO.
		575
		576	Compatibility with other modules: Coro::LWP (but see also AnyEvent::HTTP
		577	for a better-working alternative), Coro::BDB, Coro::Storable,
141	Coro::Select.	578	Coro::Select.
142		579
143	Embedding: <Coro:MakeMaker>	580	XS API: Coro::MakeMaker.
		581
		582	Low level Configuration, Thread Environment, Continuations: Coro::State.
144		583
145	AUTHOR	584	AUTHOR
146	Marc Lehmann <schmorp@schmorp.de>	585	Marc Lehmann <schmorp@schmorp.de>
147	http://home.schmorp.de/	586	http://home.schmorp.de/
148		587

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Comparing Coro/README (file contents): Revision 1.3 by root, Mon Nov 6 19:56:26 2006 UTC vs. Revision 1.21 by root, Mon Dec 15 20:52:04 2008 UTC

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Revision 1.3 by root, Mon Nov 6 19:56:26 2006 UTC vs.
Revision 1.21 by root, Mon Dec 15 20:52:04 2008 UTC