[ViewVC] Annotation of: cvs/IO-AIO/Changes

Revision history for IO::AIO

TODO: better autoconf.pm that can return LIBS etc.
TODO: aio_cptree/mvtree
TODO: reduce condvar fairness: schedule hot-cache-threads first?
TODO: splice/tee/vmsplice/sync_file_range? (http://kerneltrap.org/node/6505 http://lwn.net/Articles/178199/)
TODO: aio_fcntl, at least for file-locking

        - fix treescan output duplication and improve output ordering.
          also display files given on the commandline.
        - do our own stack memory management for threads - linux
          allocates outrageous amounts of VM (not so bad unless you
          use mlockall...), which severely limits the number of threads
          on 32-bit arches: stack size is the larger of PTHREAD_STACK_MIN
          and 4096 * sizeof (long) (usually this is 16..64k).

2.6  Sun Mar 30 08:28:11 CEST 2008
        - added aio_sync.
        - added aio_pathsync.
        - fix prototypes of (void) functions.

2.51 Sat Oct  6 16:04:54 CEST 2007
        - perlio isn't generally threadsafe, so aio_close could not work reliably.
          aio_close now tries a safe hack that might not be that asynchronous
          (see the manpage for details).
        - discard callback return values as to not grow the stack endlessly
          when poll_cb handles many requests without returning.
        - minor code cleanups.

2.5  Thu Oct  4 14:49:08 CEST 2007
        - replaced _fd2fh with faster xs code.
        - aio_close will now try to do "the right thing" and thus might
          work sensibly for the very first time.

2.41 Mon Sep 24 21:28:21 CEST 2007
        - after fork, invest some work to make sure that the poll_fileno
          stays stable (by dup2'ing the new fd over the old one), to make
          it easier for programs/libs that don't control their forking
          behaviour and cannot recreate their watchers.

2.4  Sun Aug  5 18:44:22 CEST 2007
        - add aio_truncate, aio_chmod, aio_chown, aio_utime (linux
          successfully demonstrated that you can block on futimes...).
        - allow undef as fileoffset for aio_read/write and use read/write(2)
          internally (useful for sockets or O_APPEND handles).
        - allow undef for length in aio_write.
        - negative dataoffsets work as expected now in aio_read/aio_write.
        - use NV instead of UV for 32 bit perls and file offsets, as NVs
          have a larger range then.
        - shared code between BDB and IO::AIO.
        - aio_busy was completely broken. now fixed.
        - readahead emulation now returns something.
        - correctly set errno to ENOSYS on unimplemented functions
          (should never happen, though).
        - large changes to make it partially compile and run on win32,
          but win32 lacks too much functionality, and perl overrides way
          too many functions with crashing versions.

2.33 Tue Jan 23 23:55:41 CET 2007
        - fix install path (Andreas J. Koenig).

2.32 Mon Jan 22 16:56:23 CET 2007
        - added aio_rmtree.
        - wow, aio_mkdir was missing.
        - aio_load did return undef on error, not -1.
        - use prefixexp not prefix in autoconf.pm
          (suggested by ... rt.cpan.org unreachable).
        - avoid installing autoconf.pm.

2.31 Sat Jan  6 03:46:02 CET 2007
        - added aio_load.

2.3  Sat Dec 23 05:48:07 CET 2006
        - fix off-by-one bug in aio_read, causing memory corruption
          or crashes.

2.21  Fri Dec 22 05:03:38 CET 2006
        - minor doc updates.
        - minor cleanups.
        - IO::AIO::poll returns request count.
        - undocumented and unfinished async-signal-reporting.

2.2  Tue Oct 31 00:31:00 CET 2006
        - minor doc updates.
        - added aio_readlink.
        - properly zero-terminate aio_read buffer.
        - fix aio_read/write with nonzero dataoffset.
        - reduced size of aio request structure.
        - better diagnostics when pathnames etc. are not byte-encoded;
          do not leak request in that case, either.

2.1  Sun Oct 29 02:01:57 CET 2006
        - INCOMPATIBLE CHANGE: replace IO::AIO::poll_some by
          IO::AIO::max_poll_reqs and IO::AIO::max_poll_time.
        - fix a bug in aio_move where it would fail everytime
          it would have to copy files manually.
        - doc updates.
        - start threads only on (very low) demand.
        - end superfluous threads automatically after 10s idling.
        - add IO::AIO::max_idle to control this.
        - some tuning applied to random places.
        - add aio_mknod.

2.0  Thu Oct 26 18:27:58 CEST 2006
        - minor incompatibility: max_outstanding semantics have changed.
        - major rewrite, consider all functionality EXPERIMENTAL.
        - aio requests can be cancelled.
        - callbacks can be (re-)set later.
        - aio requests can choose between 9 priorities.
        - add aio_group: aio requests can be grouped
          into composite requests.
        - generator interface for groups.
        - add IO::AIO::poll_some.
        - major documentation improvements.
        - very minor bugfixes.
        - add aio_nop for dummy requests.
        - add aio_busy mainly for benchmarking and debugging.
        - use "fast" mutexes on linux.
        - use dynamic (and larger) buffers instead of
          putting them onto the stack.
        - optimise x86 and amd64 a bit.
        - better error checking when ENOMEM.
        - hopefully fix mem and dirp leaks on fork.
        - warn about broken perl malloc.
        - compiles on cygwin (but pread is broken on cygwin
          which is not detected by autoconf, so you have to
          edit autoconf/config.h yourself to enable emulation).

1.8  Sat Jun 24 22:20:44 CEST 2006
        - add and/or document aio_rename, aio_link, aio_symlink and aio_move.

1.73 Wed Mar  1 22:49:32 CET 2006
        - codename "jost"
        - AIX/Solaris(?) aren't being helpful again, hardcode a value
          for NAME_MAX and drive with your eyes closed (reported by
          wcooley@nakedape.cc).

1.72 Thu Feb  2 00:40:44 CET 2006
        - another minor bug in aio_scandir, again, the callback was called
          twice when the directory can't be stat'ed.

1.71 Mon Dec 26 20:20:03 CET 2005
        - grr, another minor bug in aio_scandir, this time resulting
          in a runtime error.

1.7  Mon Dec 26 19:29:48 CET 2005
        - aio_scandir errornously called callback twice in some cases.
        - added AnyEvent example.

1.61 Wed Sep  7 19:40:42 CEST 2005
        - no longer include $Config{libs}, as distros include too much
          garbage in there that is not installed on typical systems
          (for example, debian links perl against -lgdbm and many more
          libraries despite perl not needing it, slowing down startup and
          wasting memory).

1.6  Tue Aug 30 17:44:44 CEST 2005
        - added aio_readdir, aio_scandir.
        - added aio_sendfile, including sendfile emulation when sendfile
          isn't available. Linux, FreeBSD and HP-UX might work (sendfilev
          support is unavailable on my solaris 8 machine, but preliminary
          code is there. What's lacking is configury stuff and testing...).

1.5  Sat Aug 20 02:32:19 CEST 2005
        - create the aio threads on demand only (good after forking).
        - somebody nagged about C89 compatibility, so this release should
          be C89 compatible, but no guarantees for future ones.
        - abort when the configure script fails.

1.4  Wed Aug 17 08:07:27 CEST 2005
        - forgot to recreate the pipe after forking, this could cause
          deadlocks.

1.3  Wed Aug 17 07:25:54 CEST 2005
        - properly propagate exceptions from callbacks, instead of silently
          eating them.
        - use a different fork algorithm that avoids recursive callback
          invocations and reduces fork latency in busy processes.
        - fix a bug where the buffer scalar in aio_read got assigned the wrong
          length after reading.
        - fix a bug where the child would process some outstanding requests
          from the parent.
        - make a copy of the callback scalar, to avoid some very uncommon
          (but valid) usages where the callback scalar changes.
        - the callback was never freed in aio_read/aio_write.
        - aio_read/aio_write will now set the readonly flag on the data
          scalar for better error reporting.

1.2  Wed Aug 17 01:22:58 CEST 2005
        - verified on cygwin, linux/amd64+ia32+alpha, solaris.
        - use SvPVbyte for filenames now. You *need* to encode your strings to
          the external filename encoding first.
        - fix the bug where filehandles could leak (again).
        - clarify freebsd situation: make it work and tell me how, or go away
          with your underdocumented, broken and outdated OS.
        - fork'ing should now be officially supported (where linux and
          posix contradict each other, I followed posix).
        - only call read() once per poll, not twice (speedup).
        - new functions: aio_rmdir, aio_symlink.
        - force callback arguments to be undef or a reference, for better
          error catching.

1.1  Sun Aug  7 05:27:23 CEST 2005
        - added configure script to detect availability of some calls.
          (imperfect, as we cannot detect things like -lrt due to missing
          feedback yet).
        - emulate fdatasync via fsync, pread/pwrite via unsafe read/write
          and readahead via manual reading on platforms lacking those.
        - ported t/03_errors.t+framework by Brad Fitzpatrick
          from Linux::AIO.
        - removed XOPEN_SOURCE because stupid solaris 9 doesn't
          compile with it enabled. Probably breaks others. Oh well.
        - try to be more careful with errno on non-threaded perls.
        - cygwins perl insisted on a matching open mode when morphing
          the fd to an fh.
        - convert sv's to "byte" encoding in aio_read/aio_write. Might
          do that for pathnames, too, in the future, so make sure you
          properly encode your pathnames.

1.0  Fri Jul 22 10:43:30 CEST 2005
        - aio_open did not reliably deliver (open) filehandles.
        - all aio_*-functions keep a reference to the filehandle so
          it doesn't go away while the aio requests is working on it.
        - disable warnings in AIO.pm.

0.9  Wed Jul 20 23:55:04 CEST 2005
        - allow recursive calls to poll_cb, use less locking calls, too.
        - fix the Gtk2-example in the SYNOPSIS.
        - use pread/pwrite not pread64/pwrite64. this was simply a leftover
          from Linux::AIO.
          (found by compiling on cygwin. Unfortunately, cygwin declares but
          does not implement pread/pwrite).
        - only include <sys/syscall.h> on linux.

0.5  Tue Jul 12 13:03:09 CEST 2005
        - removed #include <endian.h>, it's not portable, and we don't
          need it anyway.
        - link against -lrt, as it might contain goodies such as fdatasync,
          and often aio_read, which we do not use yet, but it shouldn't hurt.

0.4  Mon Jul 11 05:28:25 CEST 2005
        - added IO::AIO::flush, IO::AIO::poll.
        - make callback argument optional for all calls.

0.3  Mon Jul 11 01:42:37 CEST 2005
        - restructured manpage.
        - added SYNOPSIS with examples for Event, Glib, Tk.
        - remove explicit context support so I don't have to maintain
          it for threaded perls (i.e. it should work now :).

0.2  Sun Jul 10 22:57:12 CEST 2005
        - return immediately from poll_wait if nreqs==0.
        - get rid of the request pipe and use faster thread-thread
          communications for most requests and responses.

0.1
        - cloned from Linux::AIO, which is very similar.

Revision:	1.139
Committed:	Sat Apr 12 23:34:15 2008 UTC (16 years, 1 month ago) by root
Branch:	MAIN
Changes since 1.138:	+2 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.31	Revision history for IO::AIO
2	root	1.30
3	root	1.59	TODO: better autoconf.pm that can return LIBS etc.
4	root	1.114	TODO: aio_cptree/mvtree
5	root	1.106	TODO: reduce condvar fairness: schedule hot-cache-threads first?
6	root	1.123	TODO: splice/tee/vmsplice/sync_file_range? (http://kerneltrap.org/node/6505 http://lwn.net/Articles/178199/)
7	root	1.136	TODO: aio_fcntl, at least for file-locking
8	root	1.100
9	root	1.137	- fix treescan output duplication and improve output ordering.
10			also display files given on the commandline.
11	root	1.138	- do our own stack memory management for threads - linux
12			allocates outrageous amounts of VM (not so bad unless you
13			use mlockall...), which severely limits the number of threads
14	root	1.139	on 32-bit arches: stack size is the larger of PTHREAD_STACK_MIN
15			and 4096 * sizeof (long) (usually this is 16..64k).
16	root	1.137
17	root	1.136	2.6 Sun Mar 30 08:28:11 CEST 2008
18	root	1.134	- added aio_sync.
19	root	1.135	- added aio_pathsync.
20	root	1.136	- fix prototypes of (void) functions.
21	root	1.134
22	root	1.133	2.51 Sat Oct 6 16:04:54 CEST 2007
23			- perlio isn't generally threadsafe, so aio_close could not work reliably.
24			aio_close now tries a safe hack that might not be that asynchronous
25			(see the manpage for details).
26			- discard callback return values as to not grow the stack endlessly
27			when poll_cb handles many requests without returning.
28			- minor code cleanups.
29
30	root	1.132	2.5 Thu Oct 4 14:49:08 CEST 2007
31	root	1.131	- replaced _fd2fh with faster xs code.
32			- aio_close will now try to do "the right thing" and thus might
33			work sensibly for the very first time.
34
35	root	1.130	2.41 Mon Sep 24 21:28:21 CEST 2007
36	root	1.129	- after fork, invest some work to make sure that the poll_fileno
37			stays stable (by dup2'ing the new fd over the old one), to make
38			it easier for programs/libs that don't control their forking
39			behaviour and cannot recreate their watchers.
40
41	root	1.128	2.4 Sun Aug 5 18:44:22 CEST 2007
42	root	1.127	- add aio_truncate, aio_chmod, aio_chown, aio_utime (linux
43			successfully demonstrated that you can block on futimes...).
44	root	1.124	- allow undef as fileoffset for aio_read/write and use read/write(2)
45			internally (useful for sockets or O_APPEND handles).
46	root	1.126	- allow undef for length in aio_write.
47			- negative dataoffsets work as expected now in aio_read/aio_write.
48	root	1.124	- use NV instead of UV for 32 bit perls and file offsets, as NVs
49	root	1.125	have a larger range then.
50	root	1.120	- shared code between BDB and IO::AIO.
51	root	1.127	- aio_busy was completely broken. now fixed.
52			- readahead emulation now returns something.
53	root	1.121	- correctly set errno to ENOSYS on unimplemented functions
54			(should never happen, though).
55	root	1.127	- large changes to make it partially compile and run on win32,
56			but win32 lacks too much functionality, and perl overrides way
57			too many functions with crashing versions.
58	root	1.120
59	root	1.119	2.33 Tue Jan 23 23:55:41 CET 2007
60			- fix install path (Andreas J. Koenig).
61
62	root	1.118	2.32 Mon Jan 22 16:56:23 CET 2007
63	root	1.114	- added aio_rmtree.
64	root	1.115	- wow, aio_mkdir was missing.
65	root	1.116	- aio_load did return undef on error, not -1.
66	root	1.117	- use prefixexp not prefix in autoconf.pm
67			(suggested by ... rt.cpan.org unreachable).
68	root	1.118	- avoid installing autoconf.pm.
69	root	1.114
70	root	1.113	2.31 Sat Jan 6 03:46:02 CET 2007
71	root	1.112	- added aio_load.
72
73	root	1.111	2.3 Sat Dec 23 05:48:07 CET 2006
74			- fix off-by-one bug in aio_read, causing memory corruption
75			or crashes.
76
77	root	1.110	2.21 Fri Dec 22 05:03:38 CET 2006
78	root	1.108	- minor doc updates.
79	root	1.107	- minor cleanups.
80			- IO::AIO::poll returns request count.
81	root	1.109	- undocumented and unfinished async-signal-reporting.
82	root	1.107
83	root	1.103	2.2 Tue Oct 31 00:31:00 CET 2006
84	root	1.100	- minor doc updates.
85	root	1.101	- added aio_readlink.
86			- properly zero-terminate aio_read buffer.
87			- fix aio_read/write with nonzero dataoffset.
88	root	1.104	- reduced size of aio request structure.
89	root	1.106	- better diagnostics when pathnames etc. are not byte-encoded;
90	root	1.105	do not leak request in that case, either.
91	root	1.94
92	root	1.99	2.1 Sun Oct 29 02:01:57 CET 2006
93	root	1.98	- INCOMPATIBLE CHANGE: replace IO::AIO::poll_some by
94			IO::AIO::max_poll_reqs and IO::AIO::max_poll_time.
95	root	1.95	- fix a bug in aio_move where it would fail everytime
96			it would have to copy files manually.
97	root	1.98	- doc updates.
98	root	1.94	- start threads only on (very low) demand.
99	root	1.97	- end superfluous threads automatically after 10s idling.
100	root	1.98	- add IO::AIO::max_idle to control this.
101	root	1.94	- some tuning applied to random places.
102	root	1.95	- add aio_mknod.
103	root	1.59
104	root	1.92	2.0 Thu Oct 26 18:27:58 CEST 2006
105	root	1.90	- minor incompatibility: max_outstanding semantics have changed.
106	root	1.86	- major rewrite, consider all functionality EXPERIMENTAL.
107	root	1.68	- aio requests can be cancelled.
108	root	1.81	- callbacks can be (re-)set later.
109	root	1.93	- aio requests can choose between 9 priorities.
110	root	1.83	- add aio_group: aio requests can be grouped
111			into composite requests.
112			- generator interface for groups.
113	root	1.89	- add IO::AIO::poll_some.
114	root	1.72	- major documentation improvements.
115			- very minor bugfixes.
116	root	1.76	- add aio_nop for dummy requests.
117	root	1.84	- add aio_busy mainly for benchmarking and debugging.
118	root	1.79	- use "fast" mutexes on linux.
119	root	1.80	- use dynamic (and larger) buffers instead of
120			putting them onto the stack.
121			- optimise x86 and amd64 a bit.
122			- better error checking when ENOMEM.
123	root	1.85	- hopefully fix mem and dirp leaks on fork.
124	root	1.92	- warn about broken perl malloc.
125	root	1.88	- compiles on cygwin (but pread is broken on cygwin
126			which is not detected by autoconf, so you have to
127			edit autoconf/config.h yourself to enable emulation).
128	root	1.68
129	root	1.67	1.8 Sat Jun 24 22:20:44 CEST 2006
130	root	1.66	- add and/or document aio_rename, aio_link, aio_symlink and aio_move.
131
132	root	1.65	1.73 Wed Mar 1 22:49:32 CET 2006
133			- codename "jost"
134			- AIX/Solaris(?) aren't being helpful again, hardcode a value
135			for NAME_MAX and drive with your eyes closed (reported by
136			wcooley@nakedape.cc).
137	root	1.63
138	root	1.62	1.72 Thu Feb 2 00:40:44 CET 2006
139	root	1.61	- another minor bug in aio_scandir, again, the callback was called
140			twice when the directory can't be stat'ed.
141
142	root	1.60	1.71 Mon Dec 26 20:20:03 CET 2005
143			- grr, another minor bug in aio_scandir, this time resulting
144			in a runtime error.
145
146	root	1.59	1.7 Mon Dec 26 19:29:48 CET 2005
147	root	1.58	- aio_scandir errornously called callback twice in some cases.
148	root	1.57	- added AnyEvent example.
149
150	root	1.55	1.61 Wed Sep 7 19:40:42 CEST 2005
151	root	1.54	- no longer include $Config{libs}, as distros include too much
152	root	1.56	garbage in there that is not installed on typical systems
153	root	1.54	(for example, debian links perl against -lgdbm and many more
154			libraries despite perl not needing it, slowing down startup and
155			wasting memory).
156
157	root	1.53	1.6 Tue Aug 30 17:44:44 CEST 2005
158			- added aio_readdir, aio_scandir.
159	root	1.51	- added aio_sendfile, including sendfile emulation when sendfile
160			isn't available. Linux, FreeBSD and HP-UX might work (sendfilev
161			support is unavailable on my solaris 8 machine, but preliminary
162			code is there. What's lacking is configury stuff and testing...).
163	root	1.46
164	root	1.44	1.5 Sat Aug 20 02:32:19 CEST 2005
165	root	1.51	- create the aio threads on demand only (good after forking).
166	root	1.41	- somebody nagged about C89 compatibility, so this release should
167	root	1.42	be C89 compatible, but no guarantees for future ones.
168	root	1.43	- abort when the configure script fails.
169	root	1.41
170	root	1.40	1.4 Wed Aug 17 08:07:27 CEST 2005
171	root	1.93	- forgot to recreate the pipe after forking, this could cause
172	root	1.40	deadlocks.
173
174	root	1.39	1.3 Wed Aug 17 07:25:54 CEST 2005
175	root	1.33	- properly propagate exceptions from callbacks, instead of silently
176			eating them.
177	root	1.38	- use a different fork algorithm that avoids recursive callback
178			invocations and reduces fork latency in busy processes.
179	root	1.37	- fix a bug where the buffer scalar in aio_read got assigned the wrong
180			length after reading.
181			- fix a bug where the child would process some outstanding requests
182			from the parent.
183			- make a copy of the callback scalar, to avoid some very uncommon
184			(but valid) usages where the callback scalar changes.
185			- the callback was never freed in aio_read/aio_write.
186	root	1.38	- aio_read/aio_write will now set the readonly flag on the data
187			scalar for better error reporting.
188	root	1.33
189	root	1.32	1.2 Wed Aug 17 01:22:58 CEST 2005
190			- verified on cygwin, linux/amd64+ia32+alpha, solaris.
191	root	1.31	- use SvPVbyte for filenames now. You need to encode your strings to
192			the external filename encoding first.
193	root	1.32	- fix the bug where filehandles could leak (again).
194	root	1.31	- clarify freebsd situation: make it work and tell me how, or go away
195			with your underdocumented, broken and outdated OS.
196			- fork'ing should now be officially supported (where linux and
197			posix contradict each other, I followed posix).
198	root	1.32	- only call read() once per poll, not twice (speedup).
199			- new functions: aio_rmdir, aio_symlink.
200	root	1.31	- force callback arguments to be undef or a reference, for better
201			error catching.
202	root	1.1
203	root	1.29	1.1 Sun Aug 7 05:27:23 CEST 2005
204	root	1.25	- added configure script to detect availability of some calls.
205	root	1.27	(imperfect, as we cannot detect things like -lrt due to missing
206	root	1.23	feedback yet).
207	root	1.27	- emulate fdatasync via fsync, pread/pwrite via unsafe read/write
208			and readahead via manual reading on platforms lacking those.
209	root	1.19	- ported t/03_errors.t+framework by Brad Fitzpatrick
210			from Linux::AIO.
211	root	1.18	- removed XOPEN_SOURCE because stupid solaris 9 doesn't
212			compile with it enabled. Probably breaks others. Oh well.
213	root	1.24	- try to be more careful with errno on non-threaded perls.
214	root	1.26	- cygwins perl insisted on a matching open mode when morphing
215			the fd to an fh.
216	root	1.28	- convert sv's to "byte" encoding in aio_read/aio_write. Might
217			do that for pathnames, too, in the future, so make sure you
218			properly encode your pathnames.
219	root	1.18
220	root	1.17	1.0 Fri Jul 22 10:43:30 CEST 2005
221			- aio_open did not reliably deliver (open) filehandles.
222	root	1.16	- all aio_*-functions keep a reference to the filehandle so
223			it doesn't go away while the aio requests is working on it.
224			- disable warnings in AIO.pm.
225
226	root	1.15	0.9 Wed Jul 20 23:55:04 CEST 2005
227			- allow recursive calls to poll_cb, use less locking calls, too.
228			- fix the Gtk2-example in the SYNOPSIS.
229	root	1.14	- use pread/pwrite not pread64/pwrite64. this was simply a leftover
230			from Linux::AIO.
231			(found by compiling on cygwin. Unfortunately, cygwin declares but
232			does not implement pread/pwrite).
233			- only include <sys/syscall.h> on linux.
234
235	root	1.13	0.5 Tue Jul 12 13:03:09 CEST 2005
236	root	1.12	- removed #include <endian.h>, it's not portable, and we don't
237			need it anyway.
238			- link against -lrt, as it might contain goodies such as fdatasync,
239			and often aio_read, which we do not use yet, but it shouldn't hurt.
240
241	root	1.11	0.4 Mon Jul 11 05:28:25 CEST 2005
242	root	1.9	- added IO::AIO::flush, IO::AIO::poll.
243	root	1.10	- make callback argument optional for all calls.
244	root	1.8
245	root	1.7	0.3 Mon Jul 11 01:42:37 CEST 2005
246	root	1.5	- restructured manpage.
247	root	1.7	- added SYNOPSIS with examples for Event, Glib, Tk.
248			- remove explicit context support so I don't have to maintain
249			it for threaded perls (i.e. it should work now :).
250	root	1.5
251	root	1.4	0.2 Sun Jul 10 22:57:12 CEST 2005
252	root	1.2	- return immediately from poll_wait if nreqs==0.
253			- get rid of the request pipe and use faster thread-thread
254	root	1.3	communications for most requests and responses.
255	root	1.2
256	root	1.1	0.1
257			- cloned from Linux::AIO, which is very similar.
258