Revision history for Perl extension Coro.

TODO: should explore PerlIO::coroaio (perl leaks like hell).
TODO: channel->maxsize(newsize)?
TODO: swap_sv, maybe add scope_swap_sv?
TODO: croak when async_pool tries to run canceled thread?
TODO: how to debug safe_cancel failure (vebrose mode? show how to make backtrace?)
TODO: scalar context for Coro::AIO wrappers?

TODO: State.xs could short-circuit some macros such as CORO_EXECUTE_SLF
TODO: use frame->destroy to improve Coro::EV

6.57  Wed Jul 29 15:08:44 CEST 2020
	- override AnyEvent condvar methods "properly", as AnyEvent
          has support for pluggable condvars since 2011. This also
          avoids problems with recursive waits by avoiding to mix
          impl methods with coro code.
	- allow rouse_wait to be called in a different thread.
        - slightly clarify rouse_cb/rouse_wait documentation.
	- slightly improve rouse callback performance and memory usage.
        - try to report correct calller when throwing exception in
          on $condvar->recv, not a useless line in Coro::AnyEvent.

6.56  Thu Feb 20 19:40:07 CET 2020
	- Coro::EV::time*once functions used ev_once, which is not cancelable.
          This could cause problems due to I/O watchers not being stopped up
          on exceptions/cancellation.

6.55  Fri Jul 19 17:28:09 CEST 2019
	- Coro::RWLock woke up only one reader instead of all after a wrlock
          (analyzed and patch by Maxim Skorobogatov).
        - slightly improved documentation of Coro::RWLock and RWLock testcase.
        - quickly (re)-ported to minix 3.3 before minix crashed again.

6.54  Sun Dec 16 11:06:07 CET 2018
	- reinstate Coro::Select::select prototype - it breaks more than it fixes.

6.53  Sun Dec 16 10:33:15 CET 2018
	- the autogenerated prototypes of Coro::AIO now add ";" at the end
          to avoid generating named unary operators and messing up parsing
          (mostly affects aio_mlockall 4 | 8 which was parsed as
          (aio_mlockall 4) | 8).
        - do not use a prototype for select in Coro::Select, as CORE::select also
          doesn't have one.

6.52  Tue Aug 14 18:49:43 CEST 2018
	- libcoro update: allow sharing of coro threads using the pthreads
          backend among different pthreads, as is required by Coro::Multicore.
	- always allow ->call and ->eval when the coro is the current coroutine. this
          makes it possible, among other things, to call these on $Coro::main.
	- minor code cleanups.

6.514 Thu Aug 31 18:25:31 CEST 2017
	- safe_cancel no longer croaks when called on already-destroyed
          thread, but instead "just works".

6.513 Sat Jul 15 01:18:51 CEST 2017
	- experimental 5.22 comaptibility changes (PadlistNAMES).
	- removed attributes example and made sure the other examples
          still work.
        - fix some statevar types for newer perls, should be of no consequence.

6.512 Fri Jul 14 05:03:17 CEST 2017
        - seems to pass test suite down till 5.8.9, so make this the
          minimum requirement in Makefile.PL.
	- experimental 5.24 compatibility changes (SUB_ARGARRAY).
        - experimental 5.26 compatibility changes (PL_comppad -> PADOFFSET).
        - disable FORTIFY_SOURCE to avoid broken (but well-intentioned)
          fortified longjmp variants in some libcs.
	- re-try JIT allocation without PROT_EXEC, to hopefully improve
          portability (still doesn't seem to work around broken selinux
          mmap everywhere).
        - speling fixes (Xavier Guimard).

6.511 Sun Jun 26 23:44:50 CEST 2016
	- make it compile with threaded perls again.
	- simplify and speed up __DIE__ and __WARN__ handling.

6.51 Sat Jun 25 20:57:20 CEST 2016
	- 6.5 release didn't compile on most older perls due to
          a logic error enabling experimental 5.24 code for all versions.
        - since various broken or deficient patches float around
          to work around the vtbl API breakage in perl, let's provide
          our own workaround, which seems to be much less invasive
          and more compatible than the approaches seen so far. YMMV.
	- work around assertion failure in perl_destruct on 5.24
          (analyzed by Dave Mitchell).

6.5  Wed Jun 22 22:23:50 CEST 2016
	- swap_sv swapping order was not symmetrical, causing
          wrong swaps when swap_sv was used multiple times on the
          same sv in the same thread.
        - swap_sv calls can now be undone by calling it again
          with the same variables.
        - swap_sv calls will now be undone in async_pool threads.
	- split Coro::Semaphore::up/adjust into separate xs functions
          for better error reporting, at slight codesize increase.
        - (libcoro) arm assembly support, please test and report.
        - adjust to PL_savestack changes in perl 5.24 (adapted from
          the debian patch, which unfortunately gets it wrong).

6.49 Sat Oct 17 01:40:12 CEST 2015
	- throwing an exception to a thread waiting in
          Coro::Handle using Coro::EV did not stop the watchers,
          causing the next call to fail (testcase by Martin Pritchard).
	- bump minimum perl version to 5.10.

6.48 Sun Oct  4 19:03:51 CEST 2015
	- fix memory leak when Coro::Handle uses Coro::EV internally
          (testcase by Sten Sten).
        - update code to libev 4 API (internally, Coro still used the
          version 3 API calls).
        - remove unused hv_sig.

6.47 Sat Jul 11 03:58:20 CEST 2015
	- swap_svs - NVs can be in the SV head beginning with 5.20.

6.46 Tue Jun 30 14:36:30 CEST 2015
	- restore portability to perls with windows fork emulation
          (patch by Petr Písař).

6.45 Tue Jun 30 01:40:08 CEST 2015
	- restore portability to perl 5.16 and below.

6.44 Tue Jun 30 00:41:54 CEST 2015
	- avoid segfaulting (or worse) when tracing a canceled thread.
	- the Event module silently broke it's public hook API, causing
          failures on perls compiled with -Duselongdouble. Requiring
          the latest version of Event because I don't know which release
          changed this (it's not mentioned in the ChangeLog).
        - allow xs level enterleave hooks via CoroAPI.

6.43 Thu Jun  4 15:38:14 CEST 2015
	- use stability canary.
	- port to stableperl-5.22.0-1.001.
        - update libecb.

6.42 Wed Feb 11 20:29:52 CET 2015
	- Coro::SemaphoreSet->try did not actually work (analyzed by
          SATO Kentaro).
        - upgrade libecb to be C11 compliant.

6.41 Sat Sep  6 22:08:46 CEST 2014
	- restore portability to perl 5.8.x.
        - give new Coro's a valid GvHV(PL_hintgv) - this is slow and takes
          up some memory, but fixes "use feature" and similar modules
          when used inside a Coro.
        - allow zero as argument to Coro::Channel to mean the same thing
          as no argument. this works with older versions as well,
          but wasn't legal until now.
        - slightly better c header file detection.

6.39 Mon Jun  2 00:00:08 CEST 2014
	- work around more incompatible changes in 5.20.

6.38 Sun Jun  1 21:54:23 CEST 2014
	- check that perl slots actually have enough space to hold
          interpreter variables.
	- untested port to perl 5.19 (64 bit tmps indices) (reported
          by Andreas König).
	- croak when cancel is called without a thread context.

6.37 Tue Mar  4 13:27:33 CET 2014
	- *sigh*, removed leftover debugging code from debugging a
          perl bug, of all things.

6.36 Tue Mar  4 07:11:59 CET 2014
	- semaphores would not clear the destroy hook when interrupted
          by ->throw, causing segfaults or worse.
        - ->throw on a thread waiting for a semaphore did not acquire
          the semaphore, but also didn't wake up other waiters,
          possibly causing a deadlock.
	- "FATAL: $Coro::IDLE blocked itself" will now use Carp::confess
          to report a full stacktrace, which should help find out
          where the actual call is.
        - "atomically" destroy data in slf_destroy, because it is
          the right thing to do, just in case.
        - disable ecb.h libm dependency, to compile on ancient systems
          or under adverse conditions.

6.33 Mon Nov 18 11:26:27 CET 2013
	- do not crash when freeing padlists with holes (in 5.18).
	- tentative SVt_BIND 5.19 port/fix.

6.32 Tue Nov  5 15:35:35 CET 2013
	- use a new algorithm to derive padlists for perl 5.18. The old
          one could lead to 0-pointer accesses inside perl (reported
          by Darin McBride).

6.31 Thu May  9 07:39:48 CEST 2013
	- Coro::AIO requests would crash if the thread was ready'd
          while the request was ongoing.

6.29 Wed May  8 02:55:18 CEST 2013
	- when an on_destroy handler destructs the coro currently being
          destructed a perl scalar could be accessed after being freed,
          likely causing a crash.

6.28 Wed Mar  6 06:58:02 CET 2013
	- clean remnants of existing __DIE__ and __WARN__ handlers so
          they lose their magic and will not cause segfaults later
          (testcase by Andrey Sagulin).
	- improved Coro::State documentation a bit.
        - Coro::Debug::command now flushes the output.
        - add hack detection code for x32 abi, because the braindead slugs
          who designed that made it look exactly like x86_64 without
          providing proper compile time symbols to test for it. as a result,
          this detection cannot work reliably.
        - valgrind stack registering was broken.
        - do not rely on Time::HiRes anymore in Coro::Debug.

6.23 Fri Dec  7 23:36:37 CET 2012
        - use experimental fiber implementation on native windows
        - use sizeof (void *) as multiplication factor for stack sizes,
          to accomodate the totally braindamaged microsoft 64 bit "os".
        - changed verifier host from win2k-ap510-32 to win7-sp516-32/64.
          activeperl 5.16 crashes when PerlIO_define_layer is called due
          to some bug in the perl dll, strawberry perl at least passes
          the testsuite.
        - implement Coro::Handle->peeraddr/host/port, for slightly
          improved compatibility with LWP.
	- implement 5.17 compatibility by almost blindly applying a
          good-looking patch by Father Chrysostomos.
        - move stack management functions into libcoro 3.
        - libcoro version 3 "released".
	- support magic values as timed_io_once args.
	- recommend AnyEvent 7+ or EV 4+, also require EV
          version 4 or newer for Coro::EV.

6.10 Tue Oct  9 01:14:27 CEST 2012
	- updated ecb.h, it had a typo that caused it to not compile on many
          big endian systems (reported by many people).
        - disable memory fences in ecb.h to improve portability.

6.09 Sat Oct  6 23:25:02 CEST 2012
	- Coro::EV I/O watchers were not interruptible by exceptions
          (Coro::State::throw) (testcase by sten).
        - ->throw now puts threads into the ready queue, as this seems to
          be expected by existing code, and code that doesn't cope with spurious
          wakeups needs fixing anyway.
	- use fd -1 in mmap.
        - cast I32 to int in error message printf.
        - warn about broken so-called "hardened" kernels.

6.08 Fri Apr 13 12:05:47 CEST 2012
	- be more aggressive about exiting like perl does - formerly,
          exiting from the non-main thread would not execute END blocks.

6.07 Fri Nov 11 21:21:48 CET 2011
	- work around a bug in PerlIO (setting $SIG{__WARN__} to a PVCV).
        - update ecb.h.

6.06 Mon Aug  8 23:59:48 CEST 2011
	- cygwin unfortunately patches the stack at runtime, so we use the pthreads
          backend, which is an order of magnitude slower. unfortunately, cygwins
          pthread implementation isn't very complete either, so allocate the stack
          twice just to be sure.
          (note: cygwin also enables mymalloc, which is NOT THREADSAFE ON WINDOWS,
          in its ithreaded perl - best recompile cygwin and use the 'w'indows
          backend for much better performance. also disable ithreads for
          even better performance...).

6.05 Thu Aug  4 21:36:36 CEST 2011
	- blush, condvar values would not be propagated from send to recv anymore
          (reported by Chip Salzenberg).
	- use exponential increase for the readline buffer length in
          Coro::Handle. also reduce initial allocation to 1020 from 4096 bytes.

6.04  Wed Aug  3 17:15:45 CEST 2011
	- use even more efficient and more compatible condvars for
          compatibility to AnyEvent 6.x :)
        - more inconsequential ecb.h updates.

6.03  Wed Aug  3 11:41:30 CEST 2011
	- change how Coro patches AnyEvent condvars for compatibility to
          AnyEvent 6.x.
	- update ecb.h, to no longer include <pthread.h> in case WinNT.h
          hasn't been included.

6.02  Wed Jul 13 04:35:19 CEST 2011
	- "improve portability to Gentoo" - gentoo manages to put perl variables
          in memory areas that are farther than 2gb apart, which the jit couldn't
          handle and barfed. now it's just a bit slower on gentoo and similar

6.01  Sun Jul  3 12:31:14 CEST 2011
	- workarounds are good, but the test for whether pthreads are used
          was not good. this one should be better.
        - check differently whether gcc generates cfi instructions itself.

6.0   Wed Jun 29 19:43:35 CEST 2011
	- INCOMPATIBLE CHANGE: unreferenced coro objects will now be
          destroyed and cleaned up automatically (e.g. async { schedule }).
        - implement a JIT compiler for part of the thread switch code,
          which gives a 50% speed improvement on threaded perls, and
          about 4% on non-threaded perls (so threaded perls now finally
          reach about half the speed of non-threaded perls).
        - slightly modernise Coro::Intro, add section about rouse functions.
        - avoid DEFSV and ERRSV, giving another 10% improvement
          in thread switching.
        - Coro::State->is_destroyed is now called is_zombie.
        - implement a Coro->safe_cancel method that might fail, but
          cancels in a "safer" way if it succeeds.
        - add preliminary support for DEBUGGING perls.
        - get rid of two hash-accesses when initialising a new Coro - this
          speeds up coro creation by almost a factor of two.
        - croak when a coro that is being cancelled tries to block
          (e.g. while executing a guard block), instead of crashing or
        - use a more robust and also faster method to identify Coro::State
          objects - speeds up everything a bit.
	- implement Coro->cancel in XS for a 20% speed improvement, and to
          be able to implement mutual cancellation.
	- speed up context switches by a percent or two by more efficiently
          allocating context stack entries.
        - implement Coro->join and Coro->on_destroy in XS for a speedup and
          a reduction in memory use.
        - cancelling a coro while it itself is cancelling another coro is
          now supported and working, instead of triggering an assertion.
	- be a bit more crash-resistant when calling (buggy) on_destroy
          callbacks (best effort).
        - move on_destroy into the slf_frame, to allow extension slf
          functions to have destructors.
        - get rid if coro refcounting - simply crash in other interpreter
          threads by nulling the pointers on clone.
        - simplify warn/die hook handling when loading Coro - the convoluted
          logic seems to be no longer neccessary.
        - use libecb instead of our own home-grown gcc hacks.
        - document alternatives to Coro::LWP. Please use them :)
        - work around another mindless idiotic NEEDLESS bug in openbsd/mirbsds
          sigaltstack. Really. wine suffers from it, erlang suffers from it,
          and it's known since at least 2006.

5.372 Wed Feb 23 06:14:30 CET 2011
	- apparently mingw doesn't provide a working gettimeofday, try to
          work around that by relying on Time::HiRes (indirectly brought to
          my attention by Max Maischein).
        - fix some portability issues when Time::HiRes was used.

5.371 Mon Feb 21 14:36:08 CET 2011
	- backport to windows process emulation code again.

5.37  Sat Feb 19 07:49:44 CET 2011
	- add a big "Coro thread life cycle" section to "man Coro".
	- try a tentative workaround against the breakage that 5.13 has
          introduced without depreciation period. sigh.
        - no longer use Time::HiRes if gettimeofday is available, which
          saves quite a lot of memory.

5.36  Sun Feb 13 05:33:41 CET 2011
	- automatically load Coro::Channel, Coro::RWLock, Coro::Semaphore,
          Coro::SemaphoreSet, Coro::Signal and Coro::Specific on first "new"
          method call.
        - undocument Coro::Timer::sleep and obsolete whole module.
        - optimise Coro::Timer::timeout memory and cpu usage.
        - slightly updated Coro::Intro for recent changes.
        - do not initialise PL_dirty anymore.

5.25  Thu Nov 11 01:08:39 CET 2010
	- try a different approach on netbsd - netbsd 5 finally has marginally
          working pthreads, but still broken ucontext/sigaltstack.
        - openbsd 4.8 finally got their act together, Coro works out of the box
          with asm, setjmp and pthreads (no change, just informational).

5.24  Sat Oct 23 11:27:12 CEST 2010
	- port to the EV 4.0 API.
	- work around bugs in mingw32, making strawberry perl work
          out of the box.
	- correctly modify Coro::AIO function prototypes
          so that they reflect the "no optional parameters" rule.
	- "ported" libcoro to C++.

5.23  Mon May 17 18:50:42 CEST 2010
	- be more resistant to ordering changes when initialising
          Coro::AnyEvent, Coro::EV and Coro::Event (reported by Matthias
	- document that perl 5.12 deliberately removed support for cloning.

5.22  Wed Apr 14 03:55:35 CEST 2010
	- correctly return udnef on errors in Coro::Handle::read/write
          (testcase by Marc Mims).
	- convert Coro::Util into a "perl compatibility wrapper" - the functions
          are less useful now, but are drop-in replacements for existing
          functions, listing better alternatives in the documentation. This also
          fixes a bug in Coro::LWP which naively substituted Socket::inet_aton
          with Coro::Util::inet_aton.
        - do not override $Coro::idle unconditionally in, as other
          modules could have provided their own idle coro already
          (for exmaple, Coro::AnyEvent).
	- fix Coro::Util::gethost* functions.
        - Coro::Timer corretcly exports it's symbols (reported by Hideki Yamamura).

5.21  Wed Dec 16 07:19:51 CET 2009
        - automatically load Coro::AnyEvent when AnyEvent and Coro are used
        - add some examples on how to combine other event loops with Coro in
          Coro::AnyEvent, and how to run it (and not to block). Seems to be
          the most common source of confusion.
        - try to catch people naively blocking in an event callback.
        - work around the perl filehandle bug issue in conjunction with
          older common::sense (as indirectly pointed out by ZSystem).
	- clarify the "not from signal handlers" section.

5.2   Sun Oct  4 14:54:24 CEST 2009
        - Coro::Storable destroyed the prototypes of the functions it wrapped.
        - export rouse_cb and rouse_wait by default now.
        - fix various prototype mismatches in Coro::AnyEvent and Coro::Handle.
        - new method $state->swap_sv.
        - added section on "windows process emulation" to the manpage,
          after a not-so-fruitful (nor-friendly) "discussion" with chip
          salzenberg (discussion implies arguments, but his only arguments
          were ad-hominems, one wonders why he started it in the first
          place). I hope this explains it well enough for him to understand,
          and maybe well enough for others to understand.
        - use common::sense everywhere now.
        - idle callbacks are no longer supported, use idle coros instead.
        - print a thread listing when a deadlock is detected.

5.17  Sat Aug 22 23:09:31 CEST 2009
	- work around a bug in the perl debugger causing crashes
          when running under the debugger by marking _pool_handler as nodebug.
	- speed up Coro::async considerably.
        - try some hacks to get netbsd to work "more often" - their broken
          setjmp/longjmp, ucontext *and* phtreads are really hard on Coro.
        - convert Coro to AE 5.0 API.

5.162 Tue Jul 28 04:04:03 CEST 2009
	- perl 5.8.2 is now minimum requirement.
        - skip t/19_handle.t on broken windows perls.

5.161 Wed Jul 22 04:47:38 CEST 2009
	- Coro::AnyEvent::poll could have a different prototype when EV was
          used as backend (analyzed by Tatsuhiko Miyagawa).
	- Coro::AnyEvent errornously initialised the event loop when loaded,
          not on demand.
        - try to workaround rare */t/01_unblock.t failures.

5.16  Tue Jul 21 01:44:37 CEST 2009
	- Coro::AnyEvent failed to hook into the event loop
          when no threads had been readied between detecting
          the event loop and actually running it.
	- considerably speed up Coro::Select by taking avdantage
          of AnyEvent > 4.8 and some other optimisations.
        - implement paragraph readline mode in Coro::Handle
          (based on patches by Zsbán Ambrus).
        - replace WSAEINPROGRESS by WSAEWOULDBLOCK (reported
          and analyzed by Yasuhiro MATSUMOTO).
        - clarified libcoro license and copyright.
        - someone stole my EXTRA_META!!!
        - implement Coro::Select::patch_pp_sselect and it's brother,
          for hardcode select overriding.

5.151 Mon Jul  6 05:41:57 CEST 2009
	- backport to windows process emulation code again (patch by
          Yasuhiro MATSUMOTO).
        - slightly update Coro::MakeMaker.

5.15  Tue Jun 30 10:28:06 CEST 2009
	- deprecate Coro::Socket, document how to get ipv6 support via
          AnyEvent::Socket instead.
	- implement signal->wait ($cb) interface, similar to semaphores.
        - work around SvOK not supporting getmagic, so we have to getmagic
          to test for undef :/ (reported by Matthias Waldorf).
        - load Coro::AnyEvent in all modules using AnyEvent.
        - work around perl corrupting our internal data structures,
          reported by Tokuhiro Matsuno.
        - enable per-coroutine real and cpu time gathering

5.14  Wed Jun 24 01:37:48 CEST 2009
	- provide explicit functions to "cede" to the event loop in Coro::AnyEvent,
          as this seems to have been a difficult concept (poll, sleep, idle,
        - add Coro::AnyEvent::readable/writable functions.
	- clarify Coro::EV/Event/AnyEvent manpages.
        - free per-thread global scalars in the thread calling ->cancel, to
          avoid crashes when $_, $@ etc., are magical but some of those
          had already been freed.
        - "unexperimentalise" the callback interface for Coro::Semaphore.
	- speed up ready queue management/context switching by using a linked
          list instead of an array (~5-10%).
        - implement "watch" command in Coro::Debug shells.
        - for fun, implement time-slicing as an example in the manpage.
        - if AnyEvent detects EV or Event, but we don't have Coro::EV or
          Coro::Event, use the normal AnyEvent handling instead of dieing
          (the same is true for Coro::Handle).
        - properly document Coro::EV::timed_io_once.
        - avoid unneccessary ->cancel calls in Coro::Handle.
        - maybe make it work on mingw32 with win32 backend
          (based on patch by Yasuhiro Matsumoto).

5.132 Fri May 29 09:00:39 CEST 2009
	- do not keep a reference to the argument itself in
          Coro::Semaphore::guard, as it could change later.
        - support SO_RCVBUF/SO_SNDBUF nonstandard Coro::Socket options,
          should support a prepare callback.

5.131 Mon Mar 16 23:20:37 CET 2009
	- implement and document Coro->suspend, Coro->resume.
        - fix Coro::Select implementation to not (often) close
          the passed file descriptors (testcase provided by pippijn).

5.13 Mon Dec 15 21:51:42 CET 2008
	- EXPERIMENTAL: implement dynamic winds (on_enter/on_leave).
	- don't set diehook to C<undef> but instead to NULL, to avoid
          spurious warnings.
        - fix a lot of bugs in Coro::SemaphoreSet.
        - Coro::SemaphoreSet will less often create a semaphore needlessly.
        - add Coro::SemaphoreSet::count and wait methods.
        - take advantage of the new Guard module.
        - deprecate Coro::guard.
        - try to fix the dreaded 01_unblock tests once more. I hate it when
          testsuites need more fixing than the code they are supposed to test.
        - croak in more cases when a required callback isn't resolvable.
        - fix some minor issues in Coro::State->call/eval.
        - use current coroutine context instead of a temporary one
          when temporarily switching to another coroutine.
        - do not call C-level on_destroy handlers during global destruction,
          to avoid needless segfaults.

5.12 Sun Dec  7 13:30:38 CET 2008
        - add default config for MirOS, which seems to be a bug-to-bug
          compatible fork of openbsd ("world domination by releasing
          openbsd cvs before the openbsd folks do it" or so :).
        - free_padlist did destroy the names pad, not good, but didn't
          seem to bother perl - this could fix issues such as eval ""
          inside a function called from multiple coroutines.
        - use a different method to detect destruction time.
        - be more careful when freeing padlists just before global
        - fixed and expanded the call/cc example.
        - renamed _terminate to _coro_run.
        - new method Coro::Channel->shutdown.
        - try pthreads on openbsd <4.4 (broken sigaltstack, will
          pthreads fare better?).
        - be less picky about destroying "a" running coroutine.

5.11 Tue Nov 25 21:49:05 CET 2008
	- DEBUGGING in 5.10.0 is a mess: it constantly flags perfectly
          working code with failed assertions, introducing more bugs than
          it fixes, requiring elaborate workarounds :(

5.1  Mon Nov 24 08:54:59 CET 2008
	- wrote a small introductory tutorial - Coro::Intro.
	- convert Coro::Timer, Coro::Select and Coro::Util to rouse API.
        - Coro::Select did errornously dup the file descriptors
          and didn't work with all AnyEvent backends.
        - Coro::Select wasn't imported correctly form Coro::LWP, causing blocking
          LWP data transfers.
        - disassociate c contexts from coro objects - this is agruably more
          correct, but mostly allows sharing of cctxs between coro and state
          objects, for added memory savings and speed increases.
        - bumped $Coro::POOL_RSS up to 32kb by default.
        - no longer set the optype to OP_CUSTOM, as B::* understandably
          doesn't like this very much (and we *are* a type of entersub).
        - implement state cloning, just to prove that call/cc can be done.
        - automatically load Coro::AnyEvent in Coro::Handle.
        - wrap ->cancel calls in eval inside Coro::Handle as EV watchers
          do not have this method (and don't need it either).
        - speed up generic anyevent methods in Coro::Handle by using rouse
        - allow coroutines in $Coro::IDLE, speeding up Coro::AnyEvent and
          others. It also makes the debugger happier, as you can trace
          through the idle threads now.
        - add comppad_name* and hints ($^H, %^H) to per-thread variables.
        - eg/event was pretty broken.
        - better 5.8.6 compatibility.

5.0  Thu Nov 20 10:35:05 CET 2008
	- NEW ARCHITECTURE: use the latest 4.x version if you experience
          stability issues.
        - bump API version to 7 - all dependents must be recompiled.
        - removed timed_* functions - they were not being used anyways
          and should be replaced by a more generic mechanism -
          and were annoying to support anyways :)
        - removed SemaphoreSet's waiter method - use sem method instead.
        - Coro::Semaphore->adjust didn't correctly wake up enough waiters.
        - async_pool did free a scalar value twice
          ("Attempt to unreference...").
        - fix a longstanding bug where calling terminate on a coro that
          was waiting for a semaphore that was just becoming available
          would cause a deadlock (semaphore would get into a state where
          it was available but waiters were still blocked).
        - calling throw on a coroutine that is waiting for a semaphore will
          no longer make it acquire the semaphore (and thus leak a count).
        - perl's process emulation is now not even theoretically supported
        - new functions Coro::rouse_cb and Coro::rouse_wait for easier
          conversion of callback-style to blocking-style.
        - new methods $coro->schedule_to and ->cede_to, to specifically
          schedule or cede to a specific coroutine.
        - new function Coro::Semaphore::wait.
        - use named constants in Coro::Channel (Richard Hundt).
        - directly patch the entersub opcode calling SLF functions (cede,
          transfer and so on). this does speed up context switching, but
          more importanly, it frees us from the hardcoded behaviour of
          entersub, so we might actually be able to return something from
          those functions and atcually create new ones.
        - take advantage of __builtin_frame_address on gcc.
        - expose THX in coroapi (not sure whether this was a wise decision,
          as "threaded" perls are running at half speed anyways).
        - implement execute_slf (schedule-like-function) interface that makes
          it possible to implement schedule-like-functions in XS.
        - use new SLF interface to massively speed up Coro::EV by roughly a
          factor of two.
        - used new SLF interface to massively speed up Coro::Semaphore by a
          factor of three.
        - used new SLF interface to speed up Coro::AIO by roughly a factor of
          four and reduce its memory usage considerably.
        - implement Coro::SemaphoreSet purely in terms of Coro::Semaphore,
          for a nice speedup and vastly more correct behaviour. Also implement
          a new method "sem" to get at the underlying semaphore object.
        - implement Coro::Channel in terms of Coro::Semaphore, for a moderate
          (in comparison) 20-40% speedup.
        - used new SLF interface to reimplement Coro::Signal gaining
          some unknown (because I was too lazy), but certain, speedup, and also
          making signals reliable for the first time.
        - used new SLF interface and other optimisations to speed up async_pool
          by a factor of two. It also doesn't rely on perl's exception mechanism
          to exit anymore. The overhead for terminating an async_pool, coro over
          a normal async is now very small.
        - sped up coroutine creation/destruction by 40%.
        - forgot to include Coro/libcoro/README in the dist for all these years.
        - work around a freebsd pthreads bug (manual testcancel is required as
          pthread_cond_wait isn't a cancellation point on freebsd).
        - use new rouse functions to speed up and simplify Coro::BDB.
        - make "prefer perl native functions" work with threaded perls.
        - condense Coro::Debug ps output, hint at v and w flags.
        - (libcoro) lots of minor cleanups and portability improvements.

4.914 Wed Nov 19 12:54:18 CET 2008
        - fix a disastrous bug in the readline optimisation
          introduced in 4.801.

4.913 Sat Nov 15 07:58:28 CET 2008
        - async_pool did free a scalar value twice
          ("Attempt to unreference...").

4.912 Thu Nov 13 18:31:23 CET 2008
	- minor cleanups.
        - use much larger stacks on linux and perl < 5.8.8.
        - Coro::Debug::new_unix_server did not unlink the socket
          when destroyed.

4.911 Tue Nov 11 04:26:17 CET 2008
	- "port" to threaded perls.

4.91 Mon Nov 10 05:36:38 CET 2008
        - the ->throw exception object no longer leaks.
        - creating a new cctx leaked a scopestack entry (memleak).
	- new coroutines didn't get created with a zero flags field
          (unknown impact).
	- calling ->throw on a not-yet-started coroutine should now work
          instead of being ignored.
        - ->throw is now supported on Coro::State objects.
        - clean up cctx creation code a bit.
        - entersub is actually a UNOP, not a LOGOP (not a bugfix).

4.9  Sat Nov  8 17:45:27 CET 2008
	- (libcoro) did not preserve rbp with CORO_ASM (we are getting there).
        - (libcoro) no longer leak threads in the experimental pthread backend,
          also speed it up considerably.
        - (libcoro) do not rely on makecontext passing void *'s unscathed.
        - fix compiletime dependencies on libcoro in the Makefile.
        - cctx_count wasn't always updated properly.
        - Coro::State::cctx_stacksize wasn't applied correctly.
        - new function Coro::State::cctx_max_idle.
        - the default max number of idle C contexts is now 4.
        - (libcoro) try harder to get _setjmp/_longjmp.
        - (libcoro) cleanup and extend the libcoro API to officially
          allow the creation of empty source contexts.
        - very experimental workaround for the totally broken netbsd platform.
        - tried to hack around openbsd bugs.

4.804 Wed Nov  5 16:36:00 CET 2008
	- Coro::Debug::new_unix_server would not create a non-blocking listening
          socket, sometimes causing freezes.
        - (libcoro) fix misaligned stack points for setjmp and assembly
          methods, which can cause crashes on x86/x86_64 with a sufficiently
          aggressive compiler.
        - new function: Coro::Debug::new_tcp_server.
	- move ->throw into the Coro class because it only works on coro objects.

4.803 Mon Nov  3 17:16:12 CET 2008
	- (libcoro) use a global asm statement to become independent of gcc
          otpimisations for CORO_ASM (thanks to pippijn for the idea).
        - try to workaround yet another broken bsd, this time dragonfly.

4.802 Thu Oct 30 10:56:12 CET 2008
        - support -fno-omit-frame-pointer on x86 with the assembly method.
	- tune 01_unblock.t tests a bit.

4.801 Wed Oct 22 18:33:37 CEST 2008
	- improve readline speed for very long "lines".
	- backport to 5.8.8.

4.8  Thu Oct  2 13:34:40 CEST 2008
	- new function Coro::AIO::aio_wait.
        - Coro.:AIO and Coro::BDB now "use Coro::AnyEvent".
        - greatly speed up and reduce memory usage of Coro::AIO requests.
        - implement some other µ-optimisations.

4.749 Mon Sep 29 14:40:12 CEST 2008
	- port to slow and broken pseudo-threaded perls. (courtesy pippijn).

4.748 Sat Sep 27 14:03:19 CEST 2008
	- implement, but do not document, PerlIO::cede(granularity).
	- Coro::Storable forgot to wrap Storable::pstore.
        - work around the multitude of leaks and memory corruption
          bugs in PerlIO::via by using our own C-level perliol. As a side
          effect, Coro::Storable is now much, much, much faster.

4.747 Tue Sep 23 01:59:41 CEST 2008
	- fix a per-cv memleak (one empty array was leaked per
          code reference).
        - avoid a crash in coro->call|rss when the coroutine was already
          destroyed (most noticably when using Coro::Debug::ps :)
        - also protect *Storable::FILE.
        - push up default storable granularity to 20ms.

4.746 Sun Sep 21 03:22:20 CEST 2008
        - be more insistent on locking Storable against reentrancy
          in Coro::Storable.
	- move swap_def?v and throw to Coro::State, as documented.

4.745 Thu Jul 24 00:14:38 CEST 2008
	- remove debugging code related to MgPV_nolen_const, also try to
          make it compile with perl 5.8.6 (yes, apple apparently loves
          outdated software). Reported by John S.

4.744 Tue Jul  8 22:06:35 CEST 2008
	- correctly provide default DIE/WARN handlers as documented.
	- also overwrite PL_vtbl_sigelem.svt_clear, even though current
          implementations inside perl work fine for us.

4.743 Mon Jun 16 00:21:57 CEST 2008
	- when using Coro::EV without running EV::loop it could
          result in busy-waiting for events, this has been fixed.
        - reduce codesize and improve performance by using EV_DEFAULT_UC.

4.742 Sat May 31 14:10:21 CEST 2008
	- implement a workaround for (some) perl <5.8.8 versions.
        - require EV 3.3+.

4.741 Fri May 30 23:33:09 CEST 2008
	- tell netbsd how utterly broken their imitation of an OS is
          and refuse to build by default if pthreads are in use.
        - switch to "s" method on all bsd's by default, as their ucontext
          stuff seems just too broken.
        - fix a bug in Coro::Select.

4.74 Thu May 29 20:05:31 CEST 2008
	- do not test Coro::LWP for lack of dependencies.
        - do not test Coro::Select for lack of working perls.

4.73 Thu May 29 2008
	- fix a bug in Coro::EV which would cause it to block despite
          there being runnable coroutines.
	- sprinkle "no warnings" freely over everything, also suppress
          warnings for some other modules.
        - fix typo in WSAEWOULDBLOCK.

4.72 Sun May 25 05:14:36 CEST 2008
	- tweak META.yaml a bit, unfortunately, there is no documented way
          to have optional dependencies with CPAN. doh :(
	- avoid running some tests on windows because they would fail due to
          perl bug (broken fork, broken pipes...).
        - work around perl on windows bugs where perl returns undocumented
          error codes for sysread, syswrite etc. by taking advantage
          of AnyEvent's workaround for that problem.
        - use AnyEvent::Util::fh_nonblocking in Coro::Handle to work around
          a common perl implementation bug on windows.
        - use unix domain sockets in testsuite to work around
          common perl implementation bugs on widows (they are emulated by
          tcp sockets on windows. ugh.)

4.71 Sat May 24 20:01:27 CEST 2008
	- fix a bug in Coro::AnyEvent ("Usage: Coro::AnyEvent::_schedule()").
	- take advantage of async name resolution of AnyEvent::Util.
        - work around brutal inet_aton override in Coro::LWP.
        - take advantage of the readyhook in Coro::EV, for smoother

4.7  Sun May 11 00:32:19 CEST 2008
	- completely reworked the Coro manpage.
	- added Coro::AnyEvent, generic event loop integration.
	- implement cancel, ready and kill commands in Coro::Debug.
        - document find_coro in Coro::Debug.
        - incompatible change: rename has_stack to has_cctx.
        - Coro::AIO and Coro::BDB no longer force event model detection,
          use AnyEvent::AIO and AnyEvent::BDB.

4.6  Sat Apr 26 10:05:14 CEST 2008
	- INCOMPATIBLE CHANGE: sub/code attributes are no longer supported
          by the Coro module. It was a mistake to have it in the first place.
        - (experimental) support for activestate perl 5.10 (method "w").
        - (experimental) support for strawberry perl (method "a").
        - coro_sigelem_set did not return a value although it had to,
          actual impact unknown.

4.51 Mon Apr 14 13:28:27 CEST 2008
	- make it compile again on 5.8.

4.50 Thu Apr 10 09:43:17 CEST 2008
	- I did it twice! (see 4.49).

4.49 Sun Apr  6 21:23:31 CEST 2008
	- grr, instead of compiling the recent changes on 5.10 only they
          were compiled on 5.8 only.

4.48 Sun Apr  6 20:36:46 CEST 2008
	- allow coroutine switches during eval's under 5.10.x, as it seems
          the parser is a per-interpreter option now, so this is safe
          (this might fix the odd crashing bug).
        - drop support for 5.9.x versions: they are dead, jim.

4.47 Sun Apr  6 00:37:52 CEST 2008
	- force cctx allocation on API calls: we know we need to force one
          and gcc actually manages to confuse our heuristic nowadays,
          leading to crashes and worse.
        - document force_cctx.

4.46 Fri Apr  4 22:05:43 CEST 2008
        - upgrade libcoro, resulting in pthread-backend (which was only created
          to fulfill the rules of the programming languages shootout).

4.45 Thu Mar 13 11:55:36 CET 2008
	- fix a file leaking bug in eg/mhyttpd that would allow
          downloading of any file (reported by oesi).
	- fix deadlock bug in Coro::Channel (reported by Richard Hundt)
          (also add testcase).
        - support Broadcast option in Coro::Socket (patch by Richard Hundt,
          apparently having loads of fun with that).
        - implement $state->swap_defsv, ->swap_defav and document ->throw.

4.4  Wed Feb 13 16:44:29 CET 2008
	- only assume .cfi pseudo isns exist on GNU/Linux.
        - add get_timed method to Coro::Channels.
        - fixed Coro::Debug manpage.
        - perl 5.11 compatbility improvement based on patch by
          Andreas König.

4.37 Sun Jan 20 11:25:23 CET 2008
	- soften the check for an active parser for perl 5.10 (avoiding
          "Coro::State::transfer called while parsing" in many cases).

4.36 Sun Jan 13 10:53:56 CET 2008
	- reset diehook when terminating from an async_pool as to not
          trigger any __DIE__ handlers.

4.35 Sun Jan 13 04:14:13 CET 2008
	- "bt" debug command now displays any exceptions
          from longmess and also skips the innermost
          stackframes, giving more useufl output.
	- allow backtraces in coroutines blocked in Coro::EV,
          at a <1% speed hit.
        - handle localising of $SIG{__WARN__} and __DIE__
          properly (with a proper amount of dirty hacking).

4.34 Sat Dec 22 17:49:53 CET 2007
	- upgrade to EV version 2.0 API.

4.33 Mon Dec 17 08:36:12 CET 2007
	- make Coro::AIO etc. loadable in the absence of EV.

4.32 Mon Dec 17 07:46:02 CET 2007
	- majorly improved Coro::Handle's performance with Coro::EV.
        - implemented the until now mythical Coro::BDB module.
        - specialcase EV in Coro::AIO and Coro::BDB for extra speed.

4.31 Wed Dec  5 12:32:39 CET 2007
	- remove warn statement form Coro::Util.

4.3  Tue Dec  4 20:33:14 CET 2007
	- calls to the idle function could cause stack corruption
          when the stack changed.
	- do no longer rely on the presence of EV::DNS if EV is used
          (because it is gone), but instead take avdantage of EV::ADNS
          if available.
        - add ($) prototypes to all functions in Coro::Storable.
        - use a conventional (safer) idle callback in Coro::EV.
        - do accept quickly in Coro::Debug to avoid endless loops.

4.22 Fri Nov 30 16:04:04 CET 2007
	- really use optimised versions for Event and EV in Coro::Util
          and Coro::Handle.

4.21 Sun Nov 25 10:48:59 CET 2007
	- fix a spurious memory read.
        - Coro::EV no longer keeps the eventloop "alive".

4.2  Fri Nov  9 20:47:05 CET 2007
	- enable/disable tracing from a new coroutine, not a pooled one.
        - fix a memleak in Coro::Event.
        - removed killall call from fork_eval.
        - made sure store_fd is already loaded so that fork_eval
          does not have to parse autoload in each subprocess.
        - only use assembly method if -O switch is in $Config{optimize}.
        - add (optional) Coro::EV module, so far the best event loop module
          directly supported by Coro.
        - if the event model is EV, use EV::DNS to resolve
          stuff in Coro::Util.
        - don't get confused by multiple event notifications in Coro::Handle.
        - initial support for EV (libevent interface).
        - require Event and EV using configure_requires, to force their existance.

4.13 Wed Oct 24 07:26:45 CEST 2007
	- add Coro::Storable::blocking_thaw.
        - use a vastly more complicated technique to localise
          $SIG{__WARN/DIE__} that also works on perls <= 5.8.8.
        - use a coroutine for the idle callback Coro::Event,
          instead of running Event in the current coroutine context.
          This also catches recursive invocations.
        - actually report fork errors in gethostbyname and inet_aton.

4.11 Thu Oct 11 02:40:24 CEST 2007
	- port to threaded perls.

4.1  Thu Oct 11 02:38:16 CEST 2007
	- incompatible change: $SIG{__DIE__} and $SIG{__WARN__} will now
          be local to each coro (see Coro::State).
        - incompatible change: for very deep reasons, cede and cede_notself
          cannot return anything, so nothing will be returned.
	- possibly bring back 5.10 compatibility (untested).
        - work around stupid (and wrong) warning on 5.10 :(.
	- overlay the saved state over the context stack. This saves
          a few hundred bytes per coroutine on average and also
          speeds up context switching a bit.
        - further tune default stack sizes.
        - (more) correctly calculate stack usage in coro_rss.
        - Coro::Storable::blocking_* did not properly lock
          resulting in races between coroutines.
        - added Coro::Storable::guard.
        - stopping to trace a coroutine could destroy the cctx of
          an unrelated coroutine.
        - explain the relationship between Perl and C coroutines in
          more detail in Coro::State.
        - Coro::Util::inet_aton did not short-circuit dotted quad forms,
          causing a fork per resolve. This also affected Coro::Socket.
        - switch to a separate stack in $coro->call/eval to avoid
          invalidating pointers.

4.03 Sat Oct  6 21:24:00 CEST 2007
	- added Coro::throw method.
	- minor code cleanups.

4.02 Sat Oct  6 02:36:47 CEST 2007
	- fix a very minor per-coroutine memleak (a single codereference).
	- fixed a bug where the currently in-use c context would be freed
          prematurely (can happen only when programs change the stacksize
          or use tracing).
        - tracing can no longer keep a coro alive after it terminated.
        - do static branch prediction in the common path for gcc. gives
          about 2-5% speed improvement here.

4.01 Fri Oct  5 22:10:49 CEST 2007
	- instead of recreating *a* standard output handle we simply
          use STDOUT, which is faster and hopefully more robust.

4.0  Fri Oct  5 12:56:00 CEST 2007
        - incompatibly changed Coro::Storable::freeze.
        - major new feature: added Coro::Debug, for interactive coroutine
          debugging, tracing and much more.
        - major bug fix: unbelievable, but true: $_, $/ and many other
          "saved" variables actually weren't being saved. This has been fixed,
          of course, while increasing performance while losing all the save
        - save flags are gone, and all the api functions dealing with them.
	- added Coro::Semaphore::adjust.
        - added Coro::Util::fork_eval.
        - added Coro::Storable::{nfreeze,blocking_{freeze,nfreeze}}.
        - added Coro::killall.
        - reduce initial stack sizes to allow for "micro-coroutines".
        - better async_pool resource management, moved parts of async_pool
          handling to XS (major speed improvement).
        - actually croak before modifying important data structures.
        - refuse to transfer while compiling.
        - possibly support eval EXPR better now.
        - enable assembly per default on linux+bsd x86+amd64.
        - all internal members were renamed _something for easier subclassing.
        - many minor tweaks.

3.63 Wed May 16 14:10:06 CEST 2007
	- implement handcoded assembly for x86/amd64 SVR ABI.

3.62 Fri Apr 27 21:36:06 CEST 2007
	- upgrade libcoro (which might set unwind info correctly).
        - change default on linux to setjmp/longjmp.

3.61 Thu Apr 19 12:36:18 CEST 2007
	- Coro::Storable caused an endless loop when thawing invalid
          pst's sometimes.
	- use a Semaphore in Coro::Storable, as Storable doesn't
          seem to be reentrant (although it is documented to
          be threadsafe...).
        - fix Coro::Signal to bring back the original unreliable
          but stateful semantics.
        - fixed a lot of typos in (patch submitted by David
          Steinbrunner, which applied flawlessly).

3.6  Sat Apr 14 17:13:31 CEST 2007
	- added some bugfixes to get eg/myhttpd working again.
        - added Coro::Storable for often-cede'ing freeze/thaw.
        - try to do a clean exit when a coroutine calls exit
        - got rid of indirect call through _coro_init.
        - updated the partly antique examples in eg/ to
          work again and be a bit less magic, too.
        - fixed Coro::Signal semantics to work as documented again.

3.55  Sun Mar 25 01:20:47 CET 2007
	- add SAVE_DEFFH to save the default filehandle and enable
          it by default.
        - finally move socket-operations from Coro::Socket to Coro::Handle
          to be able to unblock foreign sockets.
	- add Coro::State::save_also and guarded_save.
	- add count accessor to Coro::Semaphore.
        - add Coro::State::cctx_stacksize.
        - just for the fun of it, do not rely on implicit context,
          which can dramatically improve performance, but people
          using windows-process-emulation perls do not care much about

3.51  Sun Mar  4 14:18:04 CET 2007
	- fixed a problem when you weakened references to Coro::State's
          (patch by Yuval Kogman).

3.501 Wed Feb 28 12:44:07 CET 2007
	- rename some global symbols as macosx from hell redefines
          them without asking.

3.5 Tue Feb 13 20:22:53 CET 2007
	- do AnyEvent model detection earlier, avoiding problems
          caused by first using AnyEvent and later Coro::Event.
        - implement and document Coro::Event event objects.
        - fix a potential problem in Coro::Event causing crashes.
        - initialise PL_comppad when creating a new coroutine,
          avoids crashes on early coro destruction.

3.41 Mon Jan 22 19:19:49 CET 2007
	- readline on Coro::Handle did not support undefined $/,
          nor did it deliver partial lines on EOF or error.
        - implement malloc fallback for stack allocation because
          stupid broken idiotic OSX has a stupid broken
          idiotic fits-the-whole-os mmap "implementation" and
          my dick feels longer if Coro is portable even to
          obsolete platforms.

3.4  Fri Jan 19 21:52:54 CET 2007
	- remove t/09_timer.t, as it isn't really testing much
          but was rather flaky in practise.
        - async_pool coro would keep arguments and callback alive until
          it was reused.
        - cancellation of a coroutine could cause spurious idle calls
          in cede_notself.

3.3  Sat Jan  6 03:45:00 CET 2007
	- implement $coro->on_destroy.
        - Coro::Event blocking semantics have been changed,
          documented and - hopefully - improved.
	- fix nice adding, not subtracting, from priority.
        - fix ->prio and api_is_ready (patch by Mark Hinds).
        - fixed an assert ("... == prev__cctx->idle_te")
          that could errronously trigger.
        - fix various large and small memleaks.
        - use a (hopefully) more stable cancel implementation
          that immediately frees the coroutine data.
        - cede/cede_notself return a status now.
        - added Coro::guard function.
        - added a global coroutine pool for jobs (on my machine,
          I can create and execute 48k simple coros/s with async,
          and 128k coros with async_pool).
        - Coro::AIO now uses the coroutine priority as io priority.

3.2  Fri Dec 22 05:07:09 CET 2006
	- improve portability to slightly older perls.
        - use cleaner coroutine destruction.
        - simplify configuration for users.
        - optionally (unrecommended) prefer perl functions over
          their coro replacements.

3.11 Tue Dec  5 13:11:24 CET 2006
        - fixed some bogus assert's, but as perl.h disables assert even
          without NDEBUG (thank you very much), not too many people should
          notice (that did include myself). Andreas König noticed, though :)
	- do not save/restore PL_sortcxix on >= 5.9.x, it doesn't seem to have
          it. Also noticed by Andreas König :)
        - save/restore tainted status.
        - verified to pass the testsuite on my 5.9.5.

3.1  Mon Dec  4 23:03:40 CET 2006
        - INCOMPATIBLE CHANGE: $/ is now per-coroutine (but slow).
        - incompatible change: transfer flags are now per-state.
	- give a better error message on deadlock.
        - document Coro::nready.
        - enhanced testsuite.

3.01 Sun Dec  3 23:47:42 CET 2006
	- forgot to include Coro::Timer.

3.0  Sun Dec  3 22:57:25 CET 2006
	- the "FINALLY COMPLETELY STABLE" release (coming soon:
          the "FAMOUS LAST WORDS" release).
	- implement a new stack sharing algorithm, which uses a stack
          pool (size currently hardcoded).
        - make stack sharing mandatory (it no longer uses a heuristic).
        - eval/die no longer cause weird problems under heavy use.
        - Coro::Event could cause livelocks if it was used but
          no Coro::Event watchers were used.
        - Coro::Event now uses asynccheck as prepare does not
          check for changed watchers.
        - Coro::Event allows multiple waiting coros and will wake up one
          per event.
        - Coro::Event should be cleaner and more efficient now.
        - new utility function Coro::unblock_sub.
        - document the sad fact that Event is no longer reentrant.
        - putting a coroutine into the ready queue twice could under
          some circumstances lead to stack corruption.
        - minor incompatibility: subclassing Coro::State is supported
          directly now without going through a _coro_state member.
        - state/coro switching is much faster now.
        - very minor optimisations and code/documentation cleanup.
        - avoid problems due to compiler inlining.
        - removed timers from Coro::Timer -> use AnyEvent instead.
        - replaced Coro::idle coroutine by (cleaner) idle handler.
        - updated to newest libcoro.
        - implement enhanced support for valgrind.
        - implement is_ready and return value for ready.
        - removed Coro::Cont, it was a misnomer (it's generators),
          and it was somewhat annoying to get it right. Will come back
          if somebody asks for it :)
        - many ->wait methods and Coro::Event could return
          spuriously without the event having happened.

2.5  Tue Nov  7 12:22:33 CET 2006
        - made Coro::Util, Coro::Select, Coro::Handle and Coro::Socket
          use AnyEvent, moved them to Coro/.
	- added Coro::LWP which contains all the uglyness required to
          make LWP non-blocking.
	- should work with perl 5.9.x now (Andreas König made me do it).
        - fixed another bug in Coro::Select when the timeout was undef.
        - reuse PL_start_env for all coros, saves some memory per coroutine.
        - manage PL_top_env differently, hopefully to avoid panic: top_env.
        - timeout argument was not properly used in Coro::Socket.
        - allow limited forms of subclassing in Coro::Handle/Coro::Socket.
        - emulate undocumented(!) functionality of IO::Socket required
          by LWP(!!).
        - updated eg/lwp to work with newer lwp's.
        - remove "FATAL: uncaught exception" prefix. Coroutines that die
          kill the whole process, just as exceptions in the main "coroutine"
          did already.

2.1  Wed Nov  1 23:01:13 CET 2006
        - fix a long-standing bug in Coro::Select where select with
          zero timeout would instead change the current default filehandle.
	- use a simpler and hopefully more robust way to clone padlists
          (uses less memory and a perl function instead of our own).
        - coro can now create a stack guard area on many architectures.
        - Coro::AIO properly reexports additional functions from IO::AIO.
	- updated libcoro with a workaround for OS X,
          pach and testing by Michael Schwern.

2.0  Tue Oct 24 05:47:17 CEST 2006
	- support additional aio requests in Coro::AIO.

1.9  (never properly released due to a glitch)

1.8  Thu Feb  2 00:59:06 CET 2006
	- applied suggested patch by SAMV to avoid problems during stupid
          mark & sweep gc run.
        - applied patch by Scott Walters for 5.9.3 compatibility.

1.7  Tue Dec 27 01:41:58 CET 2005
	- added Coro::AIO, a thin wrapper around IO::AIO.
	- improved Makefile.PL explanations.

1.6  Mon Dec 12 21:30:05 CET 2005
	- additionally save PM_curpm might fix as-of-yet
          unseen problems with regex matches being attributed to the
          wrong package.
        - add t/10_bugs.t, which currently checks against imho broken
          perls that use 0.26MB of stack space per Perl_magic_get
          invocation (newer linuxes) as opposed to the 0.0002MB perl
          normally uses.
        - make stacksize configurable for the ultimate debian experience.

1.51 Mon Dec 12 18:48:36 CET 2005
	- remove debugging warn() accidentally left in Coro::Select.

1.5  Tue Nov 29 13:32:44 CET 2005
	- use Coro::Event inside Coro::Select to avoid spurious deadlocks.
        - fix Coro::Select 'select'.
        - strict'ify some modules.
	- libcoro errornously restored the SIGUSR2 handler to SIGUSR1.
        - use XSLoader in selected modules.
        - remove some 5.6 compatibility cruft.

1.4  Tue Sep  6 00:11:05 CEST 2005
	- libcoro did not take into account the trampoline on amd64,
          when 'l'inux method was used.

1.31 Tue Aug 30 23:31:33 CEST 2005
	- some portability fixes/workarounds.

1.3  Sat Aug 20 03:08:56 CEST 2005
	- no code changes. module seems to work fine.
	- improve Coro::State docs, remove reference to nonexisting
          Coro::State::flush method.
        - no longer autodetect windows, present it as an option instead.

1.2  Mon May 16 02:00:55 CEST 2005
	- included libcoro.c earlier in State.xs, might improve portability.
        - use a faster and possibly more stable Coro::Cont implementation.
        - accept x86_64 in addition to amd64 for optimized linux-amd64 support.
        - fix bugs Coro::SemaphoreSet that could cause locks never to be freed.
        - fix bugs in CoroAPI.h and document it in Coro::MakeMaker.

1.11 Thu Mar  3 18:00:52 CET 2005
	- change of contact address.

1.1 Tue Feb 22 20:51:16 CET 2005
	- support [l]inux method on amd64.
        - allow some context switches while compiling/eval'ing.

1.0  Tue Aug 10 03:47:27 CEST 2004
	- Event 0.89 fixes the bug again.
        - fix the remaining(??) memleak. I didn't free the cache-AV for
          padlists, so one AV per created anon-sub leaked.

0.97 Fri May 14 15:23:32 CEST 2004
	- remove stupid gcc extension that was an experiment only anyway.

0.96 Thu May 13 18:09:29 CEST 2004
	- tell people if they have yet another broken Event variant.
	- made Coro to work _better_ with threads (it seems that, as long
          as you use Coros in one thread only everything will work fine.
          Looking at the perl source the problem might be missing locking
          between Coro and some perl internal routines. That's not easily
        - (hopefully) got rid of the static xnext inside transfer.

0.95 Sun Feb 15 03:20:28 CET 2004
	- removed Coro::State::flush, implemented a new and much
          faster caching mechanism by attaching magic to the CV.
        - a memleak with (real) closures remains.
        - dramatically reduced size of stacks to 65536 (linux/x86), after
          observing that even myhttpd never had more than a kilobyte
          of stack in use (stack is still only physically allocated in
          pagesize increments for systems suporting mmap).
        - fix for a "cygwin-64" architecture added, proposed by Stefan Traby.
        - fix for threaded perl.

0.9  Sun Nov 23 04:32:39 CET 2003
	- fix a few very hard to track down but (of course) stupid
          memory leaks.
        - stringify version number to avoid locale problems :(.
        - perl 5.9.0 does not have SvPADBUSY, reported by Scott Walters,
          hopefully ignoring it "just works".

0.8   Wed Nov  5 19:38:40 CET 2003
	- port to perl5.005_03, but only 5.8.x+ is supported!
	- honor LocalAddr even without LocalPort in Coro::Socket.

0.7   Tue May 27 03:12:38 CEST 2003
        - the version jump indicates some level of testing, not gobs
          of new features.
	- uh... I found the prompt function in ExtUtils::MakeMaker.
          Highly correct stuff, that is...
        - fixed(?) a bug with die's in coroutines causing "panic: top_env".
          the fix is not well understood by the author, so beware :(.

0.652 Thu May  8 02:54:46 CEST 2003
	- Applied patch by Slaven Rezic to set default to "s" on FreeBSD,
          cause version 4 doesn't have ucontext.
	- Benjamin Reed reported that setjmp works fine on darwin,
          so preselect it.

0.651 Sat Mar 29 15:00:23 CET 2003
	- fix a bug in Coro::Handle where some bytes could get lost
          on reading, reported by

0.65  Sun Mar 23 00:08:26 CET 2003
	- added a README.linux-glibc.
        - new module Coro::Select.
        - also save/restore PL_comppad, fixes segfaults with 5.8.1.
          (I never claimed that I know what I am doing ;).
        - set default to setjmp/longjmp on non-x86-linux.

0.6   Thu Nov 21 11:09:06 CET 2002
        - made lazy context switching the default.
	- fixed the bug where SemaphoreSet::guard
          was the same as timed_guard and timed_guard was missing.
        - fix a memleak in Coro::Timer.
        - reclassified context sharing as not experimental.

0.534 Sun Apr 14 03:05:12 CEST 2002
	- fixed backspace => tab in header parsing (myhttpd).
        - added eg/readline, for elmex.
        - Coro::Event now calls ->start on first call instead of
          ->again, which created wrong timeouts for the first ->next.
        - fixed a bug where Coro::Socket returned a closed socket instead
          of nothing on ECONNREFUSED and similar error conditions.

0.533 Mon Feb 18 18:49:40 CET 2002
	- adapt to finally working Event-0.85.
        - fixed buggy event initialization (trapped under windows, but how
          could it possibly have worked anywhere?)

0.532 Wed Jan 16 02:45:32 CET 2002
	- removed the reference to pp_entersub, might work on
          (some) win32 perls now (testsuite works under cygwin,
          without Event, which freezes).

0.531 Mon Dec 10 22:18:44 CET 2001
	- Fixed a bug in SemaphoreSet::timed_down.

0.53  Tue Nov 27 21:11:13 CET 2001
	- some tests for Event.
        - slightly different internal architecture to get refcnt into the object
          and not the reference. might fix a few bugs, certainly did introduce
          new ones.
        - Coro::Timer (independent of Event).
        - new timed_wait functions for Coro::Signal, Semaphore, SemaphoreSet.

0.52  Tue Nov  6 21:36:18 CET 2001
	- ported to cygwin (trivial).
          patch by Gerrit P. Haase <>.
        - small setjmp code fix by

0.51  Thu Nov  1 20:39:01 CET 2001
	- terminate/cancel now work properly (otherwise termination
          could cause a "next coroutine is not and contains not..."
        - added Coro::Socket::shutdown.
        - Coro::Event::loop no is the same as Event::loop.
        - implemented terminate with args + join.

0.5   Fri Sep 28 16:15:35 CEST 2001
	- fixed "print" on a Coro::Handle. The print method worked.
	- small tweaks (seem to reduce memory consumption a lot)
          in various modules.
        - splendid use of "no warnings" scattered throughout.
        - added Coro::Handle::rbuf, fixed Coro::Handle::fh.

0.49  Sun Sep 16 02:42:45 CEST 2001
	- changed some method calls to function calls for speed
          inside Coro::Handle.
        - make Coro::Handle use an array instead of a hash for
          speed reasons.
        - IRIX mystery solved: it's SGI's NT, after all: "standard, huh?".
          sjlj and ucontext should now work.
        - IRIX-specific port for libcoro.
        - swapped order of accept results to match IO::Socket.
        - changed getsock/peername to sock/peername to match IO::Socket.
        - fixed a bug that caused segfault when returning to main task
          under some circumstances.
        - other bugfixes.

0.45  Sun Sep  2 02:54:01 CEST 2001
	- new method Coro::Handle::timeout.
        - corrected speling of to in Coro::Socket.
        - Coro::Socket::accept now returns a Coro::Socket, not a Coro::Handle.
        - Coro::Handle now supports fileno and FILENO.
        - added eg/myhttpd, a web server.
        - Coro::Socket now accepts numeric ports as well as "port(number)"
        - moved some scheduling primitives into xs code. more to come.
        - new simple priority system.
        - implemented Coro::Event using XS, almost four times faster!
        - small memory corruption problem fixed (boy that was difficult).

0.13  Wed Aug  8 16:53:07 CEST 2001
	- new method Coro::Handle::readline.
        - added eg/lwp and Coro::Handle::autoflush, to make LWP work.
          (see eg/lwp on how to make LWP non-blocking).
        - renamed Coro::Socket::new_inet to new.
        - added Coro::Util, some utility functions.
        - die/eval now works better (still get annoying (but true ;)
          "Callback called exit" messages).
        - Coro::Handle now supports timeout, and Coro::Socket Timeout.
        - much better Coro::Socket support.

0.12  Fri Jul 27 04:19:01 CEST 2001
	- do not use mmap if neither MAP_ANON nor MAP_ANONYMOUS is defined.
	- very experimental stack sharing algorithm. not 100% safe but
          should work well in practise ;)
        - added Coro::RWLock.
        - Coro::Specific now works.

0.11  Tue Jul 24 22:49:21 CEST 2001
	- added specialized hack for newer and older linux versions (fast).
        - renamed Coro::Event::IO to Coro::Handle.
        - new module Coro::Socket.

0.1   Tue Jul 24 01:47:53 CEST 2001
	- release candidate 3. A rather new internal structure :(
        - the great renaming: Damian Conway gave me a suitable replacement
          for yield.
	- added Coro/libcoro, a portable coroutine implementation for C
          (not even perl-dependent!!!), which can be used by Coro::State.
	- renamed SAVE_DEFSV (on xs-level only) to avoid symbol clash in
	- new function Coro::Event::idle.
        - the idle process is now overriden
          by default in Coro::Event.
        - Coro::Channel now enforces the size.
        - canceling events now works in all cases.
        - Coro state now include $_ and $@.
        - yet another bug workaround that I do not really understand :(
        - new module Coro::Event::IO (very undocumented) to do
          non-blocking i/o.
        - performance tuning.

0.08  Thu Jul 19 06:13:25 CEST 2001
	- release candidate 2 (new functionality).
	- add Coro::State::flush function.
        - transfer now supports a flags value (mostly for speed ATM).
        - might compile and work in the presence of threads now.
        - continuations have a saner syntax.
        - no more memleaks.

0.07  Tue Jul 17 17:40:18 CEST 2001
	- release candidate 1 ;)
	- slightly nicer code.
        - fixed a scheduling bug in Coro::Event.

0.06  Tue Jul 17 04:23:24 CEST 2001
        - ok, I found the showstopper - the same sub must not be
          re-entered in two different coroutines, otherwise => crash. I
          see no easy solution to this problem, except by walking the call
          chaing and saving/restoring the cv's, which is what I do now.
        - memory leaks still latent, especially at thread termination.
        - Coro::Event now works (haha).

0.05  Sun Jul 15 17:32:20 CEST 2001
	- fixed a few issues in Coro::Event.
        - I forgot to include Coro::Event in 0.04 :(:(:(

0.04  Sun Jul 15 05:24:59 CEST 2001
	- @_ is now properly localized.
	- Coro::State is now easier subclassable.
        - Coro::Cont now coroutine-aware.
        - Coro::Specific is a low-overhead module to create
          coroutine-specific vars.
        - Coro::Event provides a simple interface to Event.

0.03  Fri Jul 13 14:51:52 CEST 2001
	- transfer() now implemented in XS (beware).
	- new module Coro::Cont for really faked continuations.
	- big internal architecture changes: Coro::State is now
          really low-level and can thus be used to implement other
          interesting things, While "Coro::" implements a process-like
          model. Still crude and subject to change.
        - $_ and $@ are no longer being localized.

0.02  Tue Jul 10 01:38:17 CEST 2001
	- implemented "async" attribute.
        - $_ and $@ are now localized.
        - added Coro::Channel.
        - more testcases, still no docs.

0.01  Tue Jul  3 02:18:41 CEST 2001
	- original version; copied from Convert::Scalar.