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Revision 1.211 by root, Tue Sep 27 12:10:29 2011 UTC vs.
Revision 1.313 by root, Sat Sep 4 21:21:14 2021 UTC

1=head1 NAME 1=head1 NAME
2 2
3IO::AIO - Asynchronous Input/Output 3IO::AIO - Asynchronous/Advanced Input/Output
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use IO::AIO; 7 use IO::AIO;
8 8
58not well-supported or restricted (GNU/Linux doesn't allow them on normal 58not well-supported or restricted (GNU/Linux doesn't allow them on normal
59files currently, for example), and they would only support aio_read and 59files currently, for example), and they would only support aio_read and
60aio_write, so the remaining functionality would have to be implemented 60aio_write, so the remaining functionality would have to be implemented
61using threads anyway. 61using threads anyway.
62 62
63In addition to asynchronous I/O, this module also exports some rather
64arcane interfaces, such as C<madvise> or linux's C<splice> system call,
65which is why the C<A> in C<AIO> can also mean I<advanced>.
66
63Although the module will work in the presence of other (Perl-) threads, 67Although the module will work in the presence of other (Perl-) threads,
64it is currently not reentrant in any way, so use appropriate locking 68it is currently not reentrant in any way, so use appropriate locking
65yourself, always call C<poll_cb> from within the same thread, or never 69yourself, always call C<poll_cb> from within the same thread, or never
66call C<poll_cb> (or other C<aio_> functions) recursively. 70call C<poll_cb> (or other C<aio_> functions) recursively.
67 71
68=head2 EXAMPLE 72=head2 EXAMPLE
69 73
70This is a simple example that uses the EV module and loads 74This is a simple example that uses the EV module and loads
71F</etc/passwd> asynchronously: 75F</etc/passwd> asynchronously:
72 76
73 use Fcntl;
74 use EV; 77 use EV;
75 use IO::AIO; 78 use IO::AIO;
76 79
77 # register the IO::AIO callback with EV 80 # register the IO::AIO callback with EV
78 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 81 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95 98
96 # file contents now in $contents 99 # file contents now in $contents
97 print $contents; 100 print $contents;
98 101
99 # exit event loop and program 102 # exit event loop and program
100 EV::unloop; 103 EV::break;
101 }; 104 };
102 }; 105 };
103 106
104 # possibly queue up other requests, or open GUI windows, 107 # possibly queue up other requests, or open GUI windows,
105 # check for sockets etc. etc. 108 # check for sockets etc. etc.
106 109
107 # process events as long as there are some: 110 # process events as long as there are some:
108 EV::loop; 111 EV::run;
109 112
110=head1 REQUEST ANATOMY AND LIFETIME 113=head1 REQUEST ANATOMY AND LIFETIME
111 114
112Every C<aio_*> function creates a request. which is a C data structure not 115Every C<aio_*> function creates a request. which is a C data structure not
113directly visible to Perl. 116directly visible to Perl.
168use common::sense; 171use common::sense;
169 172
170use base 'Exporter'; 173use base 'Exporter';
171 174
172BEGIN { 175BEGIN {
173 our $VERSION = '4.0'; 176 our $VERSION = 4.76;
174 177
175 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close 178 our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx 179 aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177 aio_scandir aio_symlink aio_readlink aio_realpath aio_sync 180 aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178 aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate 181 aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179 aio_pathsync aio_readahead 182 aio_pathsync aio_readahead aio_fiemap aio_allocate
180 aio_rename aio_link aio_move aio_copy aio_group 183 aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown 184 aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182 aio_chmod aio_utime aio_truncate 185 aio_chmod aio_utime aio_truncate
183 aio_msync aio_mtouch aio_mlock aio_mlockall 186 aio_msync aio_mtouch aio_mlock aio_mlockall
184 aio_statvfs 187 aio_statvfs
188 aio_slurp
185 aio_wd); 189 aio_wd);
186 190
187 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 191 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 192 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189 min_parallel max_parallel max_idle idle_timeout 193 min_parallel max_parallel max_idle idle_timeout
190 nreqs nready npending nthreads 194 nreqs nready npending nthreads
191 max_poll_time max_poll_reqs 195 max_poll_time max_poll_reqs
192 sendfile fadvise madvise 196 sendfile fadvise madvise
193 mmap munmap munlock munlockall); 197 mmap munmap mremap munlock munlockall);
194 198
195 push @AIO_REQ, qw(aio_busy); # not exported 199 push @AIO_REQ, qw(aio_busy); # not exported
196 200
197 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 201 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198 202
202 206
203=head1 FUNCTIONS 207=head1 FUNCTIONS
204 208
205=head2 QUICK OVERVIEW 209=head2 QUICK OVERVIEW
206 210
207This section simply lists the prototypes of the most important functions 211This section simply lists the prototypes most of the functions for
208for quick reference. See the following sections for function-by-function 212quick reference. See the following sections for function-by-function
209documentation. 213documentation.
210 214
211 aio_wd $pathname, $callback->($wd) 215 aio_wd $pathname, $callback->($wd)
212 aio_open $pathname, $flags, $mode, $callback->($fh) 216 aio_open $pathname, $flags, $mode, $callback->($fh)
213 aio_close $fh, $callback->($status) 217 aio_close $fh, $callback->($status)
218 aio_seek $fh,$offset,$whence, $callback->($offs)
214 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 219 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 220 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 221 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217 aio_readahead $fh,$offset,$length, $callback->($retval) 222 aio_readahead $fh,$offset,$length, $callback->($retval)
218 aio_stat $fh_or_path, $callback->($status) 223 aio_stat $fh_or_path, $callback->($status)
219 aio_lstat $fh, $callback->($status) 224 aio_lstat $fh, $callback->($status)
220 aio_statvfs $fh_or_path, $callback->($statvfs) 225 aio_statvfs $fh_or_path, $callback->($statvfs)
221 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 226 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222 aio_chown $fh_or_path, $uid, $gid, $callback->($status) 227 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
228 aio_chmod $fh_or_path, $mode, $callback->($status)
223 aio_truncate $fh_or_path, $offset, $callback->($status) 229 aio_truncate $fh_or_path, $offset, $callback->($status)
224 aio_chmod $fh_or_path, $mode, $callback->($status) 230 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
231 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225 aio_unlink $pathname, $callback->($status) 232 aio_unlink $pathname, $callback->($status)
226 aio_mknod $pathname, $mode, $dev, $callback->($status) 233 aio_mknod $pathname, $mode, $dev, $callback->($status)
227 aio_link $srcpath, $dstpath, $callback->($status) 234 aio_link $srcpath, $dstpath, $callback->($status)
228 aio_symlink $srcpath, $dstpath, $callback->($status) 235 aio_symlink $srcpath, $dstpath, $callback->($status)
229 aio_readlink $pathname, $callback->($link) 236 aio_readlink $pathname, $callback->($link)
230 aio_realpath $pathname, $callback->($link) 237 aio_realpath $pathname, $callback->($path)
231 aio_rename $srcpath, $dstpath, $callback->($status) 238 aio_rename $srcpath, $dstpath, $callback->($status)
239 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232 aio_mkdir $pathname, $mode, $callback->($status) 240 aio_mkdir $pathname, $mode, $callback->($status)
233 aio_rmdir $pathname, $callback->($status) 241 aio_rmdir $pathname, $callback->($status)
234 aio_readdir $pathname, $callback->($entries) 242 aio_readdir $pathname, $callback->($entries)
235 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 243 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST 244 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN 245 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
246 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238 aio_load $pathname, $data, $callback->($status) 247 aio_load $pathname, $data, $callback->($status)
239 aio_copy $srcpath, $dstpath, $callback->($status) 248 aio_copy $srcpath, $dstpath, $callback->($status)
240 aio_move $srcpath, $dstpath, $callback->($status) 249 aio_move $srcpath, $dstpath, $callback->($status)
241 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242 aio_rmtree $pathname, $callback->($status) 250 aio_rmtree $pathname, $callback->($status)
251 aio_fcntl $fh, $cmd, $arg, $callback->($status)
252 aio_ioctl $fh, $request, $buf, $callback->($status)
243 aio_sync $callback->($status) 253 aio_sync $callback->($status)
244 aio_syncfs $fh, $callback->($status) 254 aio_syncfs $fh, $callback->($status)
245 aio_fsync $fh, $callback->($status) 255 aio_fsync $fh, $callback->($status)
246 aio_fdatasync $fh, $callback->($status) 256 aio_fdatasync $fh, $callback->($status)
247 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 257 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248 aio_pathsync $pathname, $callback->($status) 258 aio_pathsync $pathname, $callback->($status)
249 aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 259 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 260 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 261 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252 aio_mlockall $flags, $callback->($status) 262 aio_mlockall $flags, $callback->($status)
253 aio_group $callback->(...) 263 aio_group $callback->(...)
254 aio_nop $callback->() 264 aio_nop $callback->()
268 IO::AIO::idle_timeout $seconds 278 IO::AIO::idle_timeout $seconds
269 IO::AIO::max_outstanding $maxreqs 279 IO::AIO::max_outstanding $maxreqs
270 IO::AIO::nreqs 280 IO::AIO::nreqs
271 IO::AIO::nready 281 IO::AIO::nready
272 IO::AIO::npending 282 IO::AIO::npending
283 IO::AIO::reinit
284
285 $nfd = IO::AIO::get_fdlimit
286 IO::AIO::min_fdlimit $nfd
273 287
274 IO::AIO::sendfile $ofh, $ifh, $offset, $count 288 IO::AIO::sendfile $ofh, $ifh, $offset, $count
275 IO::AIO::fadvise $fh, $offset, $len, $advice 289 IO::AIO::fadvise $fh, $offset, $len, $advice
290
291 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
292 IO::AIO::munmap $scalar
293 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276 IO::AIO::madvise $scalar, $offset, $length, $advice 294 IO::AIO::madvise $scalar, $offset, $length, $advice
277 IO::AIO::mprotect $scalar, $offset, $length, $protect 295 IO::AIO::mprotect $scalar, $offset, $length, $protect
278 IO::AIO::munlock $scalar, $offset = 0, $length = undef 296 IO::AIO::munlock $scalar, $offset = 0, $length = undef
279 IO::AIO::munlockall 297 IO::AIO::munlockall
280 298
281=head2 AIO REQUEST FUNCTIONS 299 # stat extensions
300 $counter = IO::AIO::st_gen
301 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
302 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
303 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
304 $seconds = IO::AIO::st_btimesec
305 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
306
307 # very much unportable syscalls
308 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
309 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
310 IO::AIO::tee $r_fh, $w_fh, $length, $flags
311 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
312 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
313 $fh = IO::AIO::memfd_create $pathname[, $flags]
314 $fh = IO::AIO::eventfd [$initval, [$flags]]
315 $fh = IO::AIO::timerfd_create $clockid[, $flags]
316 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
317 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
318
319=head2 API NOTES
282 320
283All the C<aio_*> calls are more or less thin wrappers around the syscall 321All the C<aio_*> calls are more or less thin wrappers around the syscall
284with the same name (sans C<aio_>). The arguments are similar or identical, 322with the same name (sans C<aio_>). The arguments are similar or identical,
285and they all accept an additional (and optional) C<$callback> argument 323and they all accept an additional (and optional) C<$callback> argument
286which must be a code reference. This code reference will get called with 324which must be a code reference. This code reference will be called after
287the syscall return code (e.g. most syscalls return C<-1> on error, unlike 325the syscall has been executed in an asynchronous fashion. The results
288perl, which usually delivers "false") as its sole argument after the given 326of the request will be passed as arguments to the callback (and, if an
289syscall has been executed asynchronously. 327error occured, in C<$!>) - for most requests the syscall return code (e.g.
328most syscalls return C<-1> on error, unlike perl, which usually delivers
329"false").
330
331Some requests (such as C<aio_readdir>) pass the actual results and
332communicate failures by passing C<undef>.
290 333
291All functions expecting a filehandle keep a copy of the filehandle 334All functions expecting a filehandle keep a copy of the filehandle
292internally until the request has finished. 335internally until the request has finished.
293 336
294All functions return request objects of type L<IO::AIO::REQ> that allow 337All functions return request objects of type L<IO::AIO::REQ> that allow
295further manipulation of those requests while they are in-flight. 338further manipulation of those requests while they are in-flight.
296 339
297The pathnames you pass to these routines I<should> be absolute. The 340The pathnames you pass to these routines I<should> be absolute. The
298reason for this is that at the time the request is being executed, the 341reason for this is that at the time the request is being executed, the
299current working directory could have changed. Alternatively, you can make 342current working directory could have changed. Alternatively, you can
300sure that you never change the current working directory anywhere in 343make sure that you never change the current working directory anywhere
301the program and then use relative paths. Lastly, you can take advantage 344in the program and then use relative paths. You can also take advantage
302of IO::AIOs working directory abstraction - see the description of the 345of IO::AIOs working directory abstraction, that lets you specify paths
346relative to some previously-opened "working directory object" - see the
303C<IO::AIO::WD> class later in this document. 347description of the C<IO::AIO::WD> class later in this document.
304 348
305To encode pathnames as octets, either make sure you either: a) always pass 349To encode pathnames as octets, either make sure you either: a) always pass
306in filenames you got from outside (command line, readdir etc.) without 350in filenames you got from outside (command line, readdir etc.) without
307tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode 351tinkering, b) are in your native filesystem encoding, c) use the Encode
308your pathnames to the locale (or other) encoding in effect in the user 352module and encode your pathnames to the locale (or other) encoding in
309environment, d) use Glib::filename_from_unicode on unicode filenames or e) 353effect in the user environment, d) use Glib::filename_from_unicode on
310use something else to ensure your scalar has the correct contents. 354unicode filenames or e) use something else to ensure your scalar has the
355correct contents.
311 356
312This works, btw. independent of the internal UTF-8 bit, which IO::AIO 357This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313handles correctly whether it is set or not. 358handles correctly whether it is set or not.
359
360=head2 AIO REQUEST FUNCTIONS
314 361
315=over 4 362=over 4
316 363
317=item $prev_pri = aioreq_pri [$pri] 364=item $prev_pri = aioreq_pri [$pri]
318 365
348 395
349 396
350=item aio_open $pathname, $flags, $mode, $callback->($fh) 397=item aio_open $pathname, $flags, $mode, $callback->($fh)
351 398
352Asynchronously open or create a file and call the callback with a newly 399Asynchronously open or create a file and call the callback with a newly
353created filehandle for the file. 400created filehandle for the file (or C<undef> in case of an error).
354 401
355The pathname passed to C<aio_open> must be absolute. See API NOTES, above, 402The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356for an explanation. 403for an explanation.
357 404
358The C<$flags> argument is a bitmask. See the C<Fcntl> module for a 405The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
381following POSIX and non-POSIX constants are available (missing ones on 428following POSIX and non-POSIX constants are available (missing ones on
382your system are, as usual, C<0>): 429your system are, as usual, C<0>):
383 430
384C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>, 431C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>, 432C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>. 433C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
387 434
388 435
389=item aio_close $fh, $callback->($status) 436=item aio_close $fh, $callback->($status)
390 437
391Asynchronously close a file and call the callback with the result 438Asynchronously close a file and call the callback with the result
401Or in other words: the file descriptor will be closed, but it will not be 448Or in other words: the file descriptor will be closed, but it will not be
402free for reuse until the perl filehandle is closed. 449free for reuse until the perl filehandle is closed.
403 450
404=cut 451=cut
405 452
453=item aio_seek $fh, $offset, $whence, $callback->($offs)
454
455Seeks the filehandle to the new C<$offset>, similarly to perl's
456C<sysseek>. The C<$whence> can use the traditional values (C<0> for
457C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
458C<IO::AIO::SEEK_END>).
459
460The resulting absolute offset will be passed to the callback, or C<-1> in
461case of an error.
462
463In theory, the C<$whence> constants could be different than the
464corresponding values from L<Fcntl>, but perl guarantees they are the same,
465so don't panic.
466
467As a GNU/Linux (and maybe Solaris) extension, also the constants
468C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
469could be found. No guarantees about suitability for use in C<aio_seek> or
470Perl's C<sysseek> can be made though, although I would naively assume they
471"just work".
472
406=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 473=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407 474
408=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 475=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409 476
410Reads or writes C<$length> bytes from or to the specified C<$fh> and 477Reads or writes C<$length> bytes from or to the specified C<$fh> and
411C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> 478C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
412and calls the callback without the actual number of bytes read (or -1 on 479calls the callback with the actual number of bytes transferred (or -1 on
413error, just like the syscall). 480error, just like the syscall).
414 481
415C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to 482C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
416offset plus the actual number of bytes read. 483offset plus the actual number of bytes read.
417 484
475As native sendfile syscalls (as practically any non-POSIX interface hacked 542As native sendfile syscalls (as practically any non-POSIX interface hacked
476together in a hurry to improve benchmark numbers) tend to be rather buggy 543together in a hurry to improve benchmark numbers) tend to be rather buggy
477on many systems, this implementation tries to work around some known bugs 544on many systems, this implementation tries to work around some known bugs
478in Linux and FreeBSD kernels (probably others, too), but that might fail, 545in Linux and FreeBSD kernels (probably others, too), but that might fail,
479so you really really should check the return value of C<aio_sendfile> - 546so you really really should check the return value of C<aio_sendfile> -
480fewre bytes than expected might have been transferred. 547fewer bytes than expected might have been transferred.
481 548
482 549
483=item aio_readahead $fh,$offset,$length, $callback->($retval) 550=item aio_readahead $fh,$offset,$length, $callback->($retval)
484 551
485C<aio_readahead> populates the page cache with data from a file so that 552C<aio_readahead> populates the page cache with data from a file so that
489whole pages, so that offset is effectively rounded down to a page boundary 556whole pages, so that offset is effectively rounded down to a page boundary
490and bytes are read up to the next page boundary greater than or equal to 557and bytes are read up to the next page boundary greater than or equal to
491(off-set+length). C<aio_readahead> does not read beyond the end of the 558(off-set+length). C<aio_readahead> does not read beyond the end of the
492file. The current file offset of the file is left unchanged. 559file. The current file offset of the file is left unchanged.
493 560
494If that syscall doesn't exist (likely if your OS isn't Linux) it will be 561If that syscall doesn't exist (likely if your kernel isn't Linux) it will
495emulated by simply reading the data, which would have a similar effect. 562be emulated by simply reading the data, which would have a similar effect.
496 563
497 564
498=item aio_stat $fh_or_path, $callback->($status) 565=item aio_stat $fh_or_path, $callback->($status)
499 566
500=item aio_lstat $fh, $callback->($status) 567=item aio_lstat $fh, $callback->($status)
501 568
502Works like perl's C<stat> or C<lstat> in void context. The callback will 569Works almost exactly like perl's C<stat> or C<lstat> in void context. The
503be called after the stat and the results will be available using C<stat _> 570callback will be called after the stat and the results will be available
504or C<-s _> etc... 571using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
572and C<-T>).
505 573
506The pathname passed to C<aio_stat> must be absolute. See API NOTES, above, 574The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
507for an explanation. 575for an explanation.
508 576
509Currently, the stats are always 64-bit-stats, i.e. instead of returning an 577Currently, the stats are always 64-bit-stats, i.e. instead of returning an
516behaviour). 584behaviour).
517 585
518C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>, 586C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
519C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>, 587C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
520C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>. 588C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
589
590To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
591ACCESS>.
521 592
522Example: Print the length of F</etc/passwd>: 593Example: Print the length of F</etc/passwd>:
523 594
524 aio_stat "/etc/passwd", sub { 595 aio_stat "/etc/passwd", sub {
525 $_[0] and die "stat failed: $!"; 596 $_[0] and die "stat failed: $!";
569 namemax => 255, 640 namemax => 255,
570 frsize => 1024, 641 frsize => 1024,
571 fsid => 1810 642 fsid => 1810
572 } 643 }
573 644
574
575=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 645=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576 646
577Works like perl's C<utime> function (including the special case of $atime 647Works like perl's C<utime> function (including the special case of $atime
578and $mtime being undef). Fractional times are supported if the underlying 648and $mtime being undef). Fractional times are supported if the underlying
579syscalls support them. 649syscalls support them.
580 650
581When called with a pathname, uses utimes(2) if available, otherwise 651When called with a pathname, uses utimensat(2) or utimes(2) if available,
582utime(2). If called on a file descriptor, uses futimes(2) if available, 652otherwise utime(2). If called on a file descriptor, uses futimens(2)
583otherwise returns ENOSYS, so this is not portable. 653or futimes(2) if available, otherwise returns ENOSYS, so this is not
654portable.
584 655
585Examples: 656Examples:
586 657
587 # set atime and mtime to current time (basically touch(1)): 658 # set atime and mtime to current time (basically touch(1)):
588 aio_utime "path", undef, undef; 659 aio_utime "path", undef, undef;
606=item aio_truncate $fh_or_path, $offset, $callback->($status) 677=item aio_truncate $fh_or_path, $offset, $callback->($status)
607 678
608Works like truncate(2) or ftruncate(2). 679Works like truncate(2) or ftruncate(2).
609 680
610 681
682=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
683
684Allocates or frees disk space according to the C<$mode> argument. See the
685linux C<fallocate> documentation for details.
686
687C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
688space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
689to deallocate a file range.
690
691IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
692(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
693C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
694to unshare shared blocks (see your L<fallocate(2)> manpage).
695
696The file system block size used by C<fallocate> is presumably the
697C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
698can dictate other limitations.
699
700If C<fallocate> isn't available or cannot be emulated (currently no
701emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
702
703
611=item aio_chmod $fh_or_path, $mode, $callback->($status) 704=item aio_chmod $fh_or_path, $mode, $callback->($status)
612 705
613Works like perl's C<chmod> function. 706Works like perl's C<chmod> function.
614 707
615 708
652 745
653 746
654=item aio_realpath $pathname, $callback->($path) 747=item aio_realpath $pathname, $callback->($path)
655 748
656Asynchronously make the path absolute and resolve any symlinks in 749Asynchronously make the path absolute and resolve any symlinks in
657C<$path>. The resulting path only consists of directories (Same as 750C<$path>. The resulting path only consists of directories (same as
658L<Cwd::realpath>). 751L<Cwd::realpath>).
659 752
660This request can be used to get the absolute path of the current working 753This request can be used to get the absolute path of the current working
661directory by passing it a path of F<.> (a single dot). 754directory by passing it a path of F<.> (a single dot).
662 755
663 756
664=item aio_rename $srcpath, $dstpath, $callback->($status) 757=item aio_rename $srcpath, $dstpath, $callback->($status)
665 758
666Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as 759Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667rename(2) and call the callback with the result code. 760rename(2) and call the callback with the result code.
761
762On systems that support the AIO::WD working directory abstraction
763natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
764of failing, C<rename> is called on the absolute path of C<$wd>.
765
766
767=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
768
769Basically a version of C<aio_rename> with an additional C<$flags>
770argument. Calling this with C<$flags=0> is the same as calling
771C<aio_rename>.
772
773Non-zero flags are currently only supported on GNU/Linux systems that
774support renameat2. Other systems fail with C<ENOSYS> in this case.
775
776The following constants are available (missing ones are, as usual C<0>),
777see renameat2(2) for details:
778
779C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
780and C<IO::AIO::RENAME_WHITEOUT>.
668 781
669 782
670=item aio_mkdir $pathname, $mode, $callback->($status) 783=item aio_mkdir $pathname, $mode, $callback->($status)
671 784
672Asynchronously mkdir (create) a directory and call the callback with 785Asynchronously mkdir (create) a directory and call the callback with
677=item aio_rmdir $pathname, $callback->($status) 790=item aio_rmdir $pathname, $callback->($status)
678 791
679Asynchronously rmdir (delete) a directory and call the callback with the 792Asynchronously rmdir (delete) a directory and call the callback with the
680result code. 793result code.
681 794
795On systems that support the AIO::WD working directory abstraction
796natively, the case C<[$wd, "."]> is specialcased - instead of failing,
797C<rmdir> is called on the absolute path of C<$wd>.
798
682 799
683=item aio_readdir $pathname, $callback->($entries) 800=item aio_readdir $pathname, $callback->($entries)
684 801
685Unlike the POSIX call of the same name, C<aio_readdir> reads an entire 802Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
686directory (i.e. opendir + readdir + closedir). The entries will not be 803directory (i.e. opendir + readdir + closedir). The entries will not be
701 818
702=over 4 819=over 4
703 820
704=item IO::AIO::READDIR_DENTS 821=item IO::AIO::READDIR_DENTS
705 822
706When this flag is off, then the callback gets an arrayref consisting of 823Normally the callback gets an arrayref consisting of names only (as
707names only (as with C<aio_readdir>), otherwise it gets an arrayref with 824with C<aio_readdir>). If this flag is set, then the callback gets an
708C<[$name, $type, $inode]> arrayrefs, each describing a single directory 825arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
709entry in more detail. 826single directory entry in more detail:
710 827
711C<$name> is the name of the entry. 828C<$name> is the name of the entry.
712 829
713C<$type> is one of the C<IO::AIO::DT_xxx> constants: 830C<$type> is one of the C<IO::AIO::DT_xxx> constants:
714 831
715C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>, 832C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
716C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>, 833C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
717C<IO::AIO::DT_WHT>. 834C<IO::AIO::DT_WHT>.
718 835
719C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to 836C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
720know, you have to run stat yourself. Also, for speed reasons, the C<$type> 837to know, you have to run stat yourself. Also, for speed/memory reasons,
721scalars are read-only: you can not modify them. 838the C<$type> scalars are read-only: you must not modify them.
722 839
723C<$inode> is the inode number (which might not be exact on systems with 64 840C<$inode> is the inode number (which might not be exact on systems with 64
724bit inode numbers and 32 bit perls). This field has unspecified content on 841bit inode numbers and 32 bit perls). This field has unspecified content on
725systems that do not deliver the inode information. 842systems that do not deliver the inode information.
726 843
737short names are tried first. 854short names are tried first.
738 855
739=item IO::AIO::READDIR_STAT_ORDER 856=item IO::AIO::READDIR_STAT_ORDER
740 857
741When this flag is set, then the names will be returned in an order 858When this flag is set, then the names will be returned in an order
742suitable for stat()'ing each one. That is, when you plan to stat() 859suitable for stat()'ing each one. That is, when you plan to stat() most or
743all files in the given directory, then the returned order will likely 860all files in the given directory, then the returned order will likely be
744be fastest. 861faster.
745 862
746If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then 863If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
747the likely dirs come first, resulting in a less optimal stat order. 864then the likely dirs come first, resulting in a less optimal stat order
865for stat'ing all entries, but likely a more optimal order for finding
866subdirectories.
748 867
749=item IO::AIO::READDIR_FOUND_UNKNOWN 868=item IO::AIO::READDIR_FOUND_UNKNOWN
750 869
751This flag should not be set when calling C<aio_readdirx>. Instead, it 870This flag should not be set when calling C<aio_readdirx>. Instead, it
752is being set by C<aio_readdirx>, when any of the C<$type>'s found were 871is being set by C<aio_readdirx>, when any of the C<$type>'s found were
754C<$type>'s are known, which can be used to speed up some algorithms. 873C<$type>'s are known, which can be used to speed up some algorithms.
755 874
756=back 875=back
757 876
758 877
878=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
879
880Opens, reads and closes the given file. The data is put into C<$data>,
881which is resized as required.
882
883If C<$offset> is negative, then it is counted from the end of the file.
884
885If C<$length> is zero, then the remaining length of the file is
886used. Also, in this case, the same limitations to modifying C<$data> apply
887as when IO::AIO::mmap is used, i.e. it must only be modified in-place
888with C<substr>. If the size of the file is known, specifying a non-zero
889C<$length> results in a performance advantage.
890
891This request is similar to the older C<aio_load> request, but since it is
892a single request, it might be more efficient to use.
893
894Example: load F</etc/passwd> into C<$passwd>.
895
896 my $passwd;
897 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
898 $_[0] >= 0
899 or die "/etc/passwd: $!\n";
900
901 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
902 print $passwd;
903 };
904 IO::AIO::flush;
905
906
759=item aio_load $pathname, $data, $callback->($status) 907=item aio_load $pathname, $data, $callback->($status)
760 908
761This is a composite request that tries to fully load the given file into 909This is a composite request that tries to fully load the given file into
762memory. Status is the same as with aio_read. 910memory. Status is the same as with aio_read.
911
912Using C<aio_slurp> might be more efficient, as it is a single request.
763 913
764=cut 914=cut
765 915
766sub aio_load($$;$) { 916sub aio_load($$;$) {
767 my ($path, undef, $cb) = @_; 917 my ($path, undef, $cb) = @_;
787=item aio_copy $srcpath, $dstpath, $callback->($status) 937=item aio_copy $srcpath, $dstpath, $callback->($status)
788 938
789Try to copy the I<file> (directories not supported as either source or 939Try to copy the I<file> (directories not supported as either source or
790destination) from C<$srcpath> to C<$dstpath> and call the callback with 940destination) from C<$srcpath> to C<$dstpath> and call the callback with
791a status of C<0> (ok) or C<-1> (error, see C<$!>). 941a status of C<0> (ok) or C<-1> (error, see C<$!>).
942
943Existing destination files will be truncated.
792 944
793This is a composite request that creates the destination file with 945This is a composite request that creates the destination file with
794mode 0200 and copies the contents of the source file into it using 946mode 0200 and copies the contents of the source file into it using
795C<aio_sendfile>, followed by restoring atime, mtime, access mode and 947C<aio_sendfile>, followed by restoring atime, mtime, access mode and
796uid/gid, in that order. 948uid/gid, in that order.
906Scans a directory (similar to C<aio_readdir>) but additionally tries to 1058Scans a directory (similar to C<aio_readdir>) but additionally tries to
907efficiently separate the entries of directory C<$path> into two sets of 1059efficiently separate the entries of directory C<$path> into two sets of
908names, directories you can recurse into (directories), and ones you cannot 1060names, directories you can recurse into (directories), and ones you cannot
909recurse into (everything else, including symlinks to directories). 1061recurse into (everything else, including symlinks to directories).
910 1062
911C<aio_scandir> is a composite request that creates of many sub requests_ 1063C<aio_scandir> is a composite request that generates many sub requests.
912C<$maxreq> specifies the maximum number of outstanding aio requests that 1064C<$maxreq> specifies the maximum number of outstanding aio requests that
913this function generates. If it is C<< <= 0 >>, then a suitable default 1065this function generates. If it is C<< <= 0 >>, then a suitable default
914will be chosen (currently 4). 1066will be chosen (currently 4).
915 1067
916On error, the callback is called without arguments, otherwise it receives 1068On error, the callback is called without arguments, otherwise it receives
967 my $grp = aio_group $cb; 1119 my $grp = aio_group $cb;
968 1120
969 $maxreq = 4 if $maxreq <= 0; 1121 $maxreq = 4 if $maxreq <= 0;
970 1122
971 # get a wd object 1123 # get a wd object
972
973 aioreq_pri $pri; 1124 aioreq_pri $pri;
974 add $grp aio_wd $path, sub { 1125 add $grp aio_wd $path, sub {
1126 $_[0]
1127 or return $grp->result ();
1128
975 my $wd = [shift, "."]; 1129 my $wd = [shift, "."];
976 1130
977 # stat once 1131 # stat once
978 aioreq_pri $pri; 1132 aioreq_pri $pri;
979 add $grp aio_stat $wd, sub { 1133 add $grp aio_stat $wd, sub {
980 return $grp->result () if $_[0]; 1134 return $grp->result () if $_[0];
981 my $now = time; 1135 my $now = time;
982 my $hash1 = join ":", (stat _)[0,1,3,7,9]; 1136 my $hash1 = join ":", (stat _)[0,1,3,7,9];
1137 my $rdxflags = READDIR_DIRS_FIRST;
1138
1139 if ((stat _)[3] < 2) {
1140 # at least one non-POSIX filesystem exists
1141 # that returns useful DT_type values: btrfs,
1142 # so optimise for this here by requesting dents
1143 $rdxflags |= READDIR_DENTS;
1144 }
983 1145
984 # read the directory entries 1146 # read the directory entries
985 aioreq_pri $pri; 1147 aioreq_pri $pri;
986 add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub { 1148 add $grp aio_readdirx $wd, $rdxflags, sub {
987 my $entries = shift 1149 my ($entries, $flags) = @_
988 or return $grp->result (); 1150 or return $grp->result ();
1151
1152 if ($rdxflags & READDIR_DENTS) {
1153 # if we requested type values, see if we can use them directly.
1154
1155 # if there were any DT_UNKNOWN entries then we assume we
1156 # don't know. alternatively, we could assume that if we get
1157 # one DT_DIR, then all directories are indeed marked with
1158 # DT_DIR, but this seems not required for btrfs, and this
1159 # is basically the "btrfs can't get it's act together" code
1160 # branch.
1161 unless ($flags & READDIR_FOUND_UNKNOWN) {
1162 # now we have valid DT_ information for all entries,
1163 # so use it as an optimisation without further stat's.
1164 # they must also all be at the beginning of @$entries
1165 # by now.
1166
1167 my $dirs;
1168
1169 if (@$entries) {
1170 for (0 .. $#$entries) {
1171 if ($entries->[$_][1] != DT_DIR) {
1172 # splice out directories
1173 $dirs = [splice @$entries, 0, $_];
1174 last;
1175 }
1176 }
1177
1178 # if we didn't find any non-dir, then all entries are dirs
1179 unless ($dirs) {
1180 ($dirs, $entries) = ($entries, []);
1181 }
1182 } else {
1183 # directory is empty, so there are no sbdirs
1184 $dirs = [];
1185 }
1186
1187 # either splice'd the directories out or the dir was empty.
1188 # convert dents to filenames
1189 $_ = $_->[0] for @$dirs;
1190 $_ = $_->[0] for @$entries;
1191
1192 return $grp->result ($dirs, $entries);
1193 }
1194
1195 # cannot use, so return to our old ways
1196 # by pretending we only scanned for names.
1197 $_ = $_->[0] for @$entries;
1198 }
989 1199
990 # stat the dir another time 1200 # stat the dir another time
991 aioreq_pri $pri; 1201 aioreq_pri $pri;
992 add $grp aio_stat $wd, sub { 1202 add $grp aio_stat $wd, sub {
993 my $hash2 = join ":", (stat _)[0,1,3,7,9]; 1203 my $hash2 = join ":", (stat _)[0,1,3,7,9];
1048} 1258}
1049 1259
1050=item aio_rmtree $pathname, $callback->($status) 1260=item aio_rmtree $pathname, $callback->($status)
1051 1261
1052Delete a directory tree starting (and including) C<$path>, return the 1262Delete a directory tree starting (and including) C<$path>, return the
1053status of the final C<rmdir> only. This is a composite request that 1263status of the final C<rmdir> only. This is a composite request that
1054uses C<aio_scandir> to recurse into and rmdir directories, and unlink 1264uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1055everything else. 1265everything else.
1056 1266
1057=cut 1267=cut
1058 1268
1079 add $grp $dirgrp; 1289 add $grp $dirgrp;
1080 }; 1290 };
1081 1291
1082 $grp 1292 $grp
1083} 1293}
1294
1295=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
1296
1297=item aio_ioctl $fh, $request, $buf, $callback->($status)
1298
1299These work just like the C<fcntl> and C<ioctl> built-in functions, except
1300they execute asynchronously and pass the return value to the callback.
1301
1302Both calls can be used for a lot of things, some of which make more sense
1303to run asynchronously in their own thread, while some others make less
1304sense. For example, calls that block waiting for external events, such
1305as locking, will also lock down an I/O thread while it is waiting, which
1306can deadlock the whole I/O system. At the same time, there might be no
1307alternative to using a thread to wait.
1308
1309So in general, you should only use these calls for things that do
1310(filesystem) I/O, not for things that wait for other events (network,
1311other processes), although if you are careful and know what you are doing,
1312you still can.
1313
1314The following constants are available and can be used for normal C<ioctl>
1315and C<fcntl> as well (missing ones are, as usual C<0>):
1316
1317C<F_DUPFD_CLOEXEC>,
1318
1319C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
1320
1321C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
1322
1323C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
1324C<F_SEAL_WRITE>.
1325
1326C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
1327C<FS_IOC_FIEMAP>.
1328
1329C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
1330C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
1331
1332C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
1333C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
1334C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
1335C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
1336C<FS_FL_USER_MODIFIABLE>.
1337
1338C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
1339C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
1340C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
1341C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1084 1342
1085=item aio_sync $callback->($status) 1343=item aio_sync $callback->($status)
1086 1344
1087Asynchronously call sync and call the callback when finished. 1345Asynchronously call sync and call the callback when finished.
1088 1346
1157 }; 1415 };
1158 1416
1159 $grp 1417 $grp
1160} 1418}
1161 1419
1162=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1420=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1163 1421
1164This is a rather advanced IO::AIO call, which only works on mmap(2)ed 1422This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1165scalars (see the C<IO::AIO::mmap> function, although it also works on data 1423scalars (see the C<IO::AIO::mmap> function, although it also works on data
1166scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the 1424scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1167scalar must only be modified in-place while an aio operation is pending on 1425scalar must only be modified in-place while an aio operation is pending on
1169 1427
1170It calls the C<msync> function of your OS, if available, with the memory 1428It calls the C<msync> function of your OS, if available, with the memory
1171area starting at C<$offset> in the string and ending C<$length> bytes 1429area starting at C<$offset> in the string and ending C<$length> bytes
1172later. If C<$length> is negative, counts from the end, and if C<$length> 1430later. If C<$length> is negative, counts from the end, and if C<$length>
1173is C<undef>, then it goes till the end of the string. The flags can be 1431is C<undef>, then it goes till the end of the string. The flags can be
1174a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and 1432either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1175C<IO::AIO::MS_SYNC>. 1433C<IO::AIO::MS_INVALIDATE>.
1176 1434
1177=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) 1435=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1178 1436
1179This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1437This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1180scalars. 1438scalars.
1181 1439
1182It touches (reads or writes) all memory pages in the specified 1440It touches (reads or writes) all memory pages in the specified
1183range inside the scalar. All caveats and parameters are the same 1441range inside the scalar. All caveats and parameters are the same
1184as for C<aio_msync>, above, except for flags, which must be either 1442as for C<aio_msync>, above, except for flags, which must be either
1185C<0> (which reads all pages and ensures they are instantiated) or 1443C<0> (which reads all pages and ensures they are instantiated) or
1186C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and 1444C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1187writing an octet from it, which dirties the page). 1445writing an octet from it, which dirties the page).
1188 1446
1189=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) 1447=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1190 1448
1191This is a rather advanced IO::AIO call, which works best on mmap(2)ed 1449This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1210 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; 1468 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1211 aio_mlock $data; # mlock in background 1469 aio_mlock $data; # mlock in background
1212 1470
1213=item aio_mlockall $flags, $callback->($status) 1471=item aio_mlockall $flags, $callback->($status)
1214 1472
1215Calls the C<mlockall> function with the given C<$flags> (a combination of 1473Calls the C<mlockall> function with the given C<$flags> (a
1216C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>). 1474combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
1475C<IO::AIO::MCL_ONFAULT>).
1217 1476
1218On systems that do not implement C<mlockall>, this function returns C<-1> 1477On systems that do not implement C<mlockall>, this function returns C<-1>
1219and sets errno to C<ENOSYS>. 1478and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
1479by the system result in a return value of C<-1> with errno being set to
1480C<EINVAL>.
1220 1481
1221Note that the corresponding C<munlockall> is synchronous and is 1482Note that the corresponding C<munlockall> is synchronous and is
1222documented under L<MISCELLANEOUS FUNCTIONS>. 1483documented under L<MISCELLANEOUS FUNCTIONS>.
1223 1484
1224Example: asynchronously lock all current and future pages into memory. 1485Example: asynchronously lock all current and future pages into memory.
1225 1486
1226 aio_mlockall IO::AIO::MCL_FUTURE; 1487 aio_mlockall IO::AIO::MCL_FUTURE;
1488
1489=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1490
1491Queries the extents of the given file (by calling the Linux C<FIEMAP>
1492ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
1493the ioctl is not available on your OS, then this request will fail with
1494C<ENOSYS>.
1495
1496C<$start> is the starting offset to query extents for, C<$length> is the
1497size of the range to query - if it is C<undef>, then the whole file will
1498be queried.
1499
1500C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
1501C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
1502exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
1503the data portion.
1504
1505C<$count> is the maximum number of extent records to return. If it is
1506C<undef>, then IO::AIO queries all extents of the range. As a very special
1507case, if it is C<0>, then the callback receives the number of extents
1508instead of the extents themselves (which is unreliable, see below).
1509
1510If an error occurs, the callback receives no arguments. The special
1511C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
1512
1513Otherwise, the callback receives an array reference with extent
1514structures. Each extent structure is an array reference itself, with the
1515following members:
1516
1517 [$logical, $physical, $length, $flags]
1518
1519Flags is any combination of the following flag values (typically either C<0>
1520or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
1521
1522C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
1523C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
1524C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1525C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1526C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1527C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1528
1529At the time of this writing (Linux 3.2), this request is unreliable unless
1530C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1531it to return all extents of a range for files with a large number of
1532extents. The code (only) works around all these issues if C<$count> is
1533C<undef>.
1227 1534
1228=item aio_group $callback->(...) 1535=item aio_group $callback->(...)
1229 1536
1230This is a very special aio request: Instead of doing something, it is a 1537This is a very special aio request: Instead of doing something, it is a
1231container for other aio requests, which is useful if you want to bundle 1538container for other aio requests, which is useful if you want to bundle
1295object. This object stores the canonicalised, absolute version of the 1602object. This object stores the canonicalised, absolute version of the
1296path, and on systems that allow it, also a directory file descriptor. 1603path, and on systems that allow it, also a directory file descriptor.
1297 1604
1298Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat> 1605Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1299or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD 1606or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1300object and a pathname instead. If the pathname is absolute, the 1607object and a pathname instead (or the IO::AIO::WD object alone, which
1608gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1301IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative 1609IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1302to that IO::AIO::WD object. 1610to that IO::AIO::WD object.
1303 1611
1304For example, to get a wd object for F</etc> and then stat F<passwd> 1612For example, to get a wd object for F</etc> and then stat F<passwd>
1305inside, you would write: 1613inside, you would write:
1306 1614
1314 aio_stat [$etcdir, "passwd"], sub { 1622 aio_stat [$etcdir, "passwd"], sub {
1315 # yay 1623 # yay
1316 }; 1624 };
1317 }; 1625 };
1318 1626
1627The fact that C<aio_wd> is a request and not a normal function shows that
1319This shows that creating an IO::AIO::WD object is itself a potentially 1628creating an IO::AIO::WD object is itself a potentially blocking operation,
1320blocking operation, which is why it is done asynchronously. 1629which is why it is done asynchronously.
1630
1631To stat the directory obtained with C<aio_wd> above, one could write
1632either of the following three request calls:
1633
1634 aio_lstat "/etc" , sub { ... # pathname as normal string
1635 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1636 aio_lstat $wd , sub { ... # shorthand for the previous
1321 1637
1322As with normal pathnames, IO::AIO keeps a copy of the working directory 1638As with normal pathnames, IO::AIO keeps a copy of the working directory
1323object and the pathname string, so you could write the following without 1639object and the pathname string, so you could write the following without
1324causing any issues due to C<$path> getting reused: 1640causing any issues due to C<$path> getting reused:
1325 1641
1335There are some caveats: when directories get renamed (or deleted), the 1651There are some caveats: when directories get renamed (or deleted), the
1336pathname string doesn't change, so will point to the new directory (or 1652pathname string doesn't change, so will point to the new directory (or
1337nowhere at all), while the directory fd, if available on the system, 1653nowhere at all), while the directory fd, if available on the system,
1338will still point to the original directory. Most functions accepting a 1654will still point to the original directory. Most functions accepting a
1339pathname will use the directory fd on newer systems, and the string on 1655pathname will use the directory fd on newer systems, and the string on
1340older systems. Some functions (such as realpath) will always rely on the 1656older systems. Some functions (such as C<aio_realpath>) will always rely on
1341string form of the pathname. 1657the string form of the pathname.
1342 1658
1343So this fucntionality is mainly useful to get some protection against 1659So this functionality is mainly useful to get some protection against
1344C<chdir>, to easily get an absolute path out of a relative path for future 1660C<chdir>, to easily get an absolute path out of a relative path for future
1345reference, and to speed up doing many operations in the same directory 1661reference, and to speed up doing many operations in the same directory
1346(e.g. when stat'ing all files in a directory). 1662(e.g. when stat'ing all files in a directory).
1347 1663
1348The following functions implement this working directory abstraction: 1664The following functions implement this working directory abstraction:
1361passing C<undef> as working directory component of a pathname fails the 1677passing C<undef> as working directory component of a pathname fails the
1362request with C<ENOENT>, there is often no need for error checking in the 1678request with C<ENOENT>, there is often no need for error checking in the
1363C<aio_wd> callback, as future requests using the value will fail in the 1679C<aio_wd> callback, as future requests using the value will fail in the
1364expected way. 1680expected way.
1365 1681
1366If this call isn't available because your OS lacks it or it couldn't be
1367detected, it will be emulated by calling C<fsync> instead.
1368
1369=item IO::AIO::CWD 1682=item IO::AIO::CWD
1370 1683
1371This is a compiletime constant (object) that represents the process 1684This is a compile time constant (object) that represents the process
1372current working directory. 1685current working directory.
1373 1686
1374Specifying this object as working directory object for a pathname is as 1687Specifying this object as working directory object for a pathname is as if
1375if the pathname would be specified directly, without a directory object, 1688the pathname would be specified directly, without a directory object. For
1376e.g., these calls are functionally identical: 1689example, these calls are functionally identical:
1377 1690
1378 aio_stat "somefile", sub { ... }; 1691 aio_stat "somefile", sub { ... };
1379 aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; 1692 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1380 1693
1381=back 1694=back
1382 1695
1696To recover the path associated with an IO::AIO::WD object, you can use
1697C<aio_realpath>:
1698
1699 aio_realpath $wd, sub {
1700 warn "path is $_[0]\n";
1701 };
1702
1703Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
1704sometimes, fall back to using an absolue path.
1383 1705
1384=head2 IO::AIO::REQ CLASS 1706=head2 IO::AIO::REQ CLASS
1385 1707
1386All non-aggregate C<aio_*> functions return an object of this class when 1708All non-aggregate C<aio_*> functions return an object of this class when
1387called in non-void context. 1709called in non-void context.
1548The default value for the limit is C<0>, but note that setting a feeder 1870The default value for the limit is C<0>, but note that setting a feeder
1549automatically bumps it up to C<2>. 1871automatically bumps it up to C<2>.
1550 1872
1551=back 1873=back
1552 1874
1875
1553=head2 SUPPORT FUNCTIONS 1876=head2 SUPPORT FUNCTIONS
1554 1877
1555=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 1878=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1556 1879
1557=over 4 1880=over 4
1565 1888
1566See C<poll_cb> for an example. 1889See C<poll_cb> for an example.
1567 1890
1568=item IO::AIO::poll_cb 1891=item IO::AIO::poll_cb
1569 1892
1570Process some outstanding events on the result pipe. You have to call 1893Process some requests that have reached the result phase (i.e. they have
1894been executed but the results are not yet reported). You have to call
1895this "regularly" to finish outstanding requests.
1896
1571this regularly. Returns C<0> if all events could be processed (or there 1897Returns C<0> if all events could be processed (or there were no
1572were no events to process), or C<-1> if it returned earlier for whatever 1898events to process), or C<-1> if it returned earlier for whatever
1573reason. Returns immediately when no events are outstanding. The amount of 1899reason. Returns immediately when no events are outstanding. The amount
1574events processed depends on the settings of C<IO::AIO::max_poll_req> and 1900of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1575C<IO::AIO::max_poll_time>. 1901C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1576 1902
1577If not all requests were processed for whatever reason, the filehandle 1903If not all requests were processed for whatever reason, the poll file
1578will still be ready when C<poll_cb> returns, so normally you don't have to 1904descriptor will still be ready when C<poll_cb> returns, so normally you
1579do anything special to have it called later. 1905don't have to do anything special to have it called later.
1580 1906
1581Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes 1907Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1582ready, it can be beneficial to call this function from loops which submit 1908ready, it can be beneficial to call this function from loops which submit
1583a lot of requests, to make sure the results get processed when they become 1909a lot of requests, to make sure the results get processed when they become
1584available and not just when the loop is finished and the event loop takes 1910available and not just when the loop is finished and the event loop takes
1593 poll => 'r', async => 1, 1919 poll => 'r', async => 1,
1594 cb => \&IO::AIO::poll_cb); 1920 cb => \&IO::AIO::poll_cb);
1595 1921
1596=item IO::AIO::poll_wait 1922=item IO::AIO::poll_wait
1597 1923
1598If there are any outstanding requests and none of them in the result 1924Wait until either at least one request is in the result phase or no
1599phase, wait till the result filehandle becomes ready for reading (simply 1925requests are outstanding anymore.
1600does a C<select> on the filehandle. This is useful if you want to 1926
1601synchronously wait for some requests to finish). 1927This is useful if you want to synchronously wait for some requests to
1928become ready, without actually handling them.
1602 1929
1603See C<nreqs> for an example. 1930See C<nreqs> for an example.
1604 1931
1605=item IO::AIO::poll 1932=item IO::AIO::poll
1606 1933
1617 1944
1618Strictly equivalent to: 1945Strictly equivalent to:
1619 1946
1620 IO::AIO::poll_wait, IO::AIO::poll_cb 1947 IO::AIO::poll_wait, IO::AIO::poll_cb
1621 while IO::AIO::nreqs; 1948 while IO::AIO::nreqs;
1949
1950This function can be useful at program aborts, to make sure outstanding
1951I/O has been done (C<IO::AIO> uses an C<END> block which already calls
1952this function on normal exits), or when you are merely using C<IO::AIO>
1953for its more advanced functions, rather than for async I/O, e.g.:
1954
1955 my ($dirs, $nondirs);
1956 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1957 IO::AIO::flush;
1958 # $dirs, $nondirs are now set
1622 1959
1623=item IO::AIO::max_poll_reqs $nreqs 1960=item IO::AIO::max_poll_reqs $nreqs
1624 1961
1625=item IO::AIO::max_poll_time $seconds 1962=item IO::AIO::max_poll_time $seconds
1626 1963
1653 poll => 'r', nice => 1, 1990 poll => 'r', nice => 1,
1654 cb => &IO::AIO::poll_cb); 1991 cb => &IO::AIO::poll_cb);
1655 1992
1656=back 1993=back
1657 1994
1995
1658=head3 CONTROLLING THE NUMBER OF THREADS 1996=head3 CONTROLLING THE NUMBER OF THREADS
1659 1997
1660=over 1998=over
1661 1999
1662=item IO::AIO::min_parallel $nthreads 2000=item IO::AIO::min_parallel $nthreads
1723longer exceeded. 2061longer exceeded.
1724 2062
1725In other words, this setting does not enforce a queue limit, but can be 2063In other words, this setting does not enforce a queue limit, but can be
1726used to make poll functions block if the limit is exceeded. 2064used to make poll functions block if the limit is exceeded.
1727 2065
1728This is a very bad function to use in interactive programs because it 2066This is a bad function to use in interactive programs because it blocks,
1729blocks, and a bad way to reduce concurrency because it is inexact: Better 2067and a bad way to reduce concurrency because it is inexact. If you need to
2068issue many requests without being able to call a poll function on demand,
1730use an C<aio_group> together with a feed callback. 2069it is better to use an C<aio_group> together with a feed callback.
1731 2070
1732It's main use is in scripts without an event loop - when you want to stat 2071Its main use is in scripts without an event loop - when you want to stat a
1733a lot of files, you can write somehting like this: 2072lot of files, you can write something like this:
1734 2073
1735 IO::AIO::max_outstanding 32; 2074 IO::AIO::max_outstanding 32;
1736 2075
1737 for my $path (...) { 2076 for my $path (...) {
1738 aio_stat $path , ...; 2077 aio_stat $path , ...;
1739 IO::AIO::poll_cb; 2078 IO::AIO::poll_cb;
1740 } 2079 }
1741 2080
1742 IO::AIO::flush; 2081 IO::AIO::flush;
1743 2082
1744The call to C<poll_cb> inside the loop will normally return instantly, but 2083The call to C<poll_cb> inside the loop will normally return instantly,
1745as soon as more thna C<32> reqeusts are in-flight, it will block until 2084allowing the loop to progress, but as soon as more than C<32> requests
1746some requests have been handled. This keeps the loop from pushing a large 2085are in-flight, it will block until some requests have been handled. This
1747number of C<aio_stat> requests onto the queue. 2086keeps the loop from pushing a large number of C<aio_stat> requests onto
2087the queue (which, with many paths to stat, can use up a lot of memory).
1748 2088
1749The default value for C<max_outstanding> is very large, so there is no 2089The default value for C<max_outstanding> is very large, so there is no
1750practical limit on the number of outstanding requests. 2090practical limit on the number of outstanding requests.
1751 2091
1752=back 2092=back
1753 2093
2094
1754=head3 STATISTICAL INFORMATION 2095=head3 STATISTICAL INFORMATION
1755 2096
1756=over 2097=over
1757 2098
1758=item IO::AIO::nreqs 2099=item IO::AIO::nreqs
1775Returns the number of requests currently in the pending state (executed, 2116Returns the number of requests currently in the pending state (executed,
1776but not yet processed by poll_cb). 2117but not yet processed by poll_cb).
1777 2118
1778=back 2119=back
1779 2120
2121
2122=head3 SUBSECOND STAT TIME ACCESS
2123
2124Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
2125generally find access/modification and change times with subsecond time
2126accuracy of the system supports it, but perl's built-in functions only
2127return the integer part.
2128
2129The following functions return the timestamps of the most recent
2130stat with subsecond precision on most systems and work both after
2131C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
2132value is only meaningful after a successful C<stat>/C<lstat> call, or
2133during/after a successful C<aio_stat>/C<aio_lstat> callback.
2134
2135This is similar to the L<Time::HiRes> C<stat> functions, but can return
2136full resolution without rounding and work with standard perl C<stat>,
2137alleviating the need to call the special C<Time::HiRes> functions, which
2138do not act like their perl counterparts.
2139
2140On operating systems or file systems where subsecond time resolution is
2141not supported or could not be detected, a fractional part of C<0> is
2142returned, so it is always safe to call these functions.
2143
2144=over 4
2145
2146=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
2147
2148Return the access, modication, change or birth time, respectively,
2149including fractional part. Due to the limited precision of floating point,
2150the accuracy on most platforms is only a bit better than milliseconds
2151for times around now - see the I<nsec> function family, below, for full
2152accuracy.
2153
2154File birth time is only available when the OS and perl support it (on
2155FreeBSD and NetBSD at the time of this writing, although support is
2156adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
2157it). On systems where it isn't available, C<0> is currently returned, but
2158this might change to C<undef> in a future version.
2159
2160=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
2161
2162Returns access, modification, change and birth time all in one go, and
2163maybe more times in the future version.
2164
2165=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
2166
2167Return the fractional access, modifcation, change or birth time, in nanoseconds,
2168as an integer in the range C<0> to C<999999999>.
2169
2170Note that no accessors are provided for access, modification and
2171change times - you need to get those from C<stat _> if required (C<int
2172IO::AIO::st_atime> and so on will I<not> generally give you the correct
2173value).
2174
2175=item $seconds = IO::AIO::st_btimesec
2176
2177The (integral) seconds part of the file birth time, if available.
2178
2179=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
2180
2181Like the functions above, but returns all four times in one go (and maybe
2182more in future versions).
2183
2184=item $counter = IO::AIO::st_gen
2185
2186Returns the generation counter (in practice this is just a random number)
2187of the file. This is only available on platforms which have this member in
2188their C<struct stat> (most BSDs at the time of this writing) and generally
2189only to the root usert. If unsupported, C<0> is returned, but this might
2190change to C<undef> in a future version.
2191
2192=back
2193
2194Example: print the high resolution modification time of F</etc>, using
2195C<stat>, and C<IO::AIO::aio_stat>.
2196
2197 if (stat "/etc") {
2198 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
2199 }
2200
2201 IO::AIO::aio_stat "/etc", sub {
2202 $_[0]
2203 and return;
2204
2205 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
2206 };
2207
2208 IO::AIO::flush;
2209
2210Output of the awbove on my system, showing reduced and full accuracy:
2211
2212 stat(/etc) mtime: 1534043702.020808
2213 aio_stat(/etc) mtime: 1534043702.020807792
2214
2215
1780=head3 MISCELLANEOUS FUNCTIONS 2216=head3 MISCELLANEOUS FUNCTIONS
1781 2217
1782IO::AIO implements some functions that might be useful, but are not 2218IO::AIO implements some functions that are useful when you want to use
1783asynchronous. 2219some "Advanced I/O" function not available to in Perl, without going the
2220"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
2221counterpart.
1784 2222
1785=over 4 2223=over 4
2224
2225=item $numfd = IO::AIO::get_fdlimit
2226
2227Tries to find the current file descriptor limit and returns it, or
2228C<undef> and sets C<$!> in case of an error. The limit is one larger than
2229the highest valid file descriptor number.
2230
2231=item IO::AIO::min_fdlimit [$numfd]
2232
2233Try to increase the current file descriptor limit(s) to at least C<$numfd>
2234by changing the soft or hard file descriptor resource limit. If C<$numfd>
2235is missing, it will try to set a very high limit, although this is not
2236recommended when you know the actual minimum that you require.
2237
2238If the limit cannot be raised enough, the function makes a best-effort
2239attempt to increase the limit as much as possible, using various
2240tricks, while still failing. You can query the resulting limit using
2241C<IO::AIO::get_fdlimit>.
2242
2243If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
2244true.
1786 2245
1787=item IO::AIO::sendfile $ofh, $ifh, $offset, $count 2246=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1788 2247
1789Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>, 2248Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1790but is blocking (this makes most sense if you know the input data is 2249but is blocking (this makes most sense if you know the input data is
1807=item IO::AIO::madvise $scalar, $offset, $len, $advice 2266=item IO::AIO::madvise $scalar, $offset, $len, $advice
1808 2267
1809Simply calls the C<posix_madvise> function (see its 2268Simply calls the C<posix_madvise> function (see its
1810manpage for details). The following advice constants are 2269manpage for details). The following advice constants are
1811available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>, 2270available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1812C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>. 2271C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
2272C<IO::AIO::MADV_DONTNEED>.
2273
2274If C<$offset> is negative, counts from the end. If C<$length> is negative,
2275the remaining length of the C<$scalar> is used. If possible, C<$length>
2276will be reduced to fit into the C<$scalar>.
1813 2277
1814On systems that do not implement C<posix_madvise>, this function returns 2278On systems that do not implement C<posix_madvise>, this function returns
1815ENOSYS, otherwise the return value of C<posix_madvise>. 2279ENOSYS, otherwise the return value of C<posix_madvise>.
1816 2280
1817=item IO::AIO::mprotect $scalar, $offset, $len, $protect 2281=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1819Simply calls the C<mprotect> function on the preferably AIO::mmap'ed 2283Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1820$scalar (see its manpage for details). The following protect 2284$scalar (see its manpage for details). The following protect
1821constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>, 2285constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1822C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>. 2286C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1823 2287
2288If C<$offset> is negative, counts from the end. If C<$length> is negative,
2289the remaining length of the C<$scalar> is used. If possible, C<$length>
2290will be reduced to fit into the C<$scalar>.
2291
1824On systems that do not implement C<mprotect>, this function returns 2292On systems that do not implement C<mprotect>, this function returns
1825ENOSYS, otherwise the return value of C<mprotect>. 2293ENOSYS, otherwise the return value of C<mprotect>.
1826 2294
1827=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] 2295=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1828 2296
1829Memory-maps a file (or anonymous memory range) and attaches it to the 2297Memory-maps a file (or anonymous memory range) and attaches it to the
1830given C<$scalar>, which will act like a string scalar. 2298given C<$scalar>, which will act like a string scalar. Returns true on
2299success, and false otherwise.
1831 2300
2301The scalar must exist, but its contents do not matter - this means you
2302cannot use a nonexistant array or hash element. When in doubt, C<undef>
2303the scalar first.
2304
1832The only operations allowed on the scalar are C<substr>/C<vec> that don't 2305The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1833change the string length, and most read-only operations such as copying it 2306which don't change the string length, and most read-only operations such
1834or searching it with regexes and so on. 2307as copying it or searching it with regexes and so on.
1835 2308
1836Anything else is unsafe and will, at best, result in memory leaks. 2309Anything else is unsafe and will, at best, result in memory leaks.
1837 2310
1838The memory map associated with the C<$scalar> is automatically removed 2311The memory map associated with the C<$scalar> is automatically removed
1839when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or 2312when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1840C<IO::AIO::munmap> functions are called. 2313or C<IO::AIO::munmap> functions are called on it.
1841 2314
1842This calls the C<mmap>(2) function internally. See your system's manual 2315This calls the C<mmap>(2) function internally. See your system's manual
1843page for details on the C<$length>, C<$prot> and C<$flags> parameters. 2316page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1844 2317
1845The C<$length> must be larger than zero and smaller than the actual 2318The C<$length> must be larger than zero and smaller than the actual
1846filesize. 2319filesize.
1847 2320
1848C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>, 2321C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1849C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>, 2322C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1850 2323
1851C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or 2324C<$flags> can be a combination of
1852C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when 2325C<IO::AIO::MAP_SHARED> or
1853not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS> 2326C<IO::AIO::MAP_PRIVATE>,
2327or a number of system-specific flags (when not available, the are C<0>):
1854(which is set to C<MAP_ANON> if your system only provides this 2328C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1855constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>, 2329C<IO::AIO::MAP_LOCKED>,
1856C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or 2330C<IO::AIO::MAP_NORESERVE>,
2331C<IO::AIO::MAP_POPULATE>,
1857C<IO::AIO::MAP_NONBLOCK> 2332C<IO::AIO::MAP_NONBLOCK>,
2333C<IO::AIO::MAP_FIXED>,
2334C<IO::AIO::MAP_GROWSDOWN>,
2335C<IO::AIO::MAP_32BIT>,
2336C<IO::AIO::MAP_HUGETLB>,
2337C<IO::AIO::MAP_STACK>,
2338C<IO::AIO::MAP_FIXED_NOREPLACE>,
2339C<IO::AIO::MAP_SHARED_VALIDATE>,
2340C<IO::AIO::MAP_SYNC> or
2341C<IO::AIO::MAP_UNINITIALIZED>.
1858 2342
1859If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed. 2343If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1860 2344
1861C<$offset> is the offset from the start of the file - it generally must be 2345C<$offset> is the offset from the start of the file - it generally must be
1862a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>. 2346a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
1876 2360
1877=item IO::AIO::munmap $scalar 2361=item IO::AIO::munmap $scalar
1878 2362
1879Removes a previous mmap and undefines the C<$scalar>. 2363Removes a previous mmap and undefines the C<$scalar>.
1880 2364
2365=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
2366
2367Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
2368been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
2369C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
2370
2371Returns true if successful, and false otherwise. If the underlying mmapped
2372region has changed address, then the true value has the numerical value
2373C<1>, otherwise it has the numerical value C<0>:
2374
2375 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
2376 or die "mremap: $!";
2377
2378 if ($success*1) {
2379 warn "scalar has chanegd address in memory\n";
2380 }
2381
2382C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
2383implemented, but not supported and might go away in a future version.
2384
2385On systems where this call is not supported or is not emulated, this call
2386returns falls and sets C<$!> to C<ENOSYS>.
2387
2388=item IO::AIO::mlockall $flags
2389
2390Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
2391but is blocking.
2392
1881=item IO::AIO::munlock $scalar, $offset = 0, $length = undef 2393=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1882 2394
1883Calls the C<munlock> function, undoing the effects of a previous 2395Calls the C<munlock> function, undoing the effects of a previous
1884C<aio_mlock> call (see its description for details). 2396C<aio_mlock> call (see its description for details).
1885 2397
1887 2399
1888Calls the C<munlockall> function. 2400Calls the C<munlockall> function.
1889 2401
1890On systems that do not implement C<munlockall>, this function returns 2402On systems that do not implement C<munlockall>, this function returns
1891ENOSYS, otherwise the return value of C<munlockall>. 2403ENOSYS, otherwise the return value of C<munlockall>.
2404
2405=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
2406
2407Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
2408and return the new file handle on success, or sets C<$!> and returns
2409C<undef> on error.
2410
2411The remote name of the new socket will be stored in C<$sockaddr>, which
2412will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
2413socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
2414by returning a longer string in C<$sockaddr>, which might or might not be
2415truncated.
2416
2417To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
2418C<$sockaddr_maxlen>.
2419
2420The main reasons to use this syscall rather than portable C<accept(2)>
2421are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
2422flags and you can accept name-less sockets by specifying C<0> for
2423C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
2424C<accept>.
2425
2426=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2427
2428Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2429C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
2430should be the file offset.
2431
2432C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
2433silently corrupt the data in this case.
2434
2435The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
2436C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
2437C<IO::AIO::SPLICE_F_GIFT>.
2438
2439See the C<splice(2)> manpage for details.
2440
2441=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2442
2443Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2444description for C<IO::AIO::splice> above for details.
2445
2446=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
2447
2448Attempts to query or change the pipe buffer size. Obviously works only
2449on pipes, and currently works only on GNU/Linux systems, and fails with
2450C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
2451size on other systems, drop me a note.
2452
2453=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
2454
2455This is a direct interface to the Linux L<pipe2(2)> system call. If
2456C<$flags> is missing or C<0>, then this should be the same as a call to
2457perl's built-in C<pipe> function and create a new pipe, and works on
2458systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
2459(..., 4096, O_BINARY)>.
2460
2461If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
2462the given flags (Linux 2.6.27, glibc 2.9).
2463
2464On success, the read and write file handles are returned.
2465
2466On error, nothing will be returned. If the pipe2 syscall is missing and
2467C<$flags> is non-zero, fails with C<ENOSYS>.
2468
2469Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
2470time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
2471C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
2472
2473Example: create a pipe race-free w.r.t. threads and fork:
2474
2475 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
2476 or die "pipe2: $!\n";
2477
2478=item $fh = IO::AIO::memfd_create $pathname[, $flags]
2479
2480This is a direct interface to the Linux L<memfd_create(2)> system
2481call. The (unhelpful) default for C<$flags> is C<0>, but your default
2482should be C<IO::AIO::MFD_CLOEXEC>.
2483
2484On success, the new memfd filehandle is returned, otherwise returns
2485C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
2486
2487Please refer to L<memfd_create(2)> for more info on this call.
2488
2489The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
2490C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
2491
2492Example: create a new memfd.
2493
2494 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
2495 or die "memfd_create: $!\n";
2496
2497=item $fh = IO::AIO::pidfd_open $pid[, $flags]
2498
2499This is an interface to the Linux L<pidfd_open(2)> system call. The
2500default for C<$flags> is C<0>.
2501
2502On success, a new pidfd filehandle is returned (that is already set to
2503close-on-exec), otherwise returns C<undef>. If the syscall is missing,
2504fails with C<ENOSYS>.
2505
2506Example: open pid 6341 as pidfd.
2507
2508 my $fh = IO::AIO::pidfd_open 6341
2509 or die "pidfd_open: $!\n";
2510
2511=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
2512
2513This is an interface to the Linux L<pidfd_send_signal> system call. The
2514default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
2515
2516Returns the system call status. If the syscall is missing, fails with
2517C<ENOSYS>.
2518
2519When specified, C<$siginfo> must be a reference to a hash with one or more
2520of the following members:
2521
2522=over
2523
2524=item code - the C<si_code> member
2525
2526=item pid - the C<si_pid> member
2527
2528=item uid - the C<si_uid> member
2529
2530=item value_int - the C<si_value.sival_int> member
2531
2532=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
2533
2534=back
2535
2536Example: send a SIGKILL to the specified process.
2537
2538 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2539 and die "pidfd_send_signal: $!\n";
2540
2541Example: send a SIGKILL to the specified process with extra data.
2542
2543 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2544 and die "pidfd_send_signal: $!\n";
2545
2546=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2547
2548This is an interface to the Linux L<pidfd_getfd> system call. The default
2549for C<$flags> is C<0>.
2550
2551On success, returns a dup'ed copy of the target file descriptor (specified
2552as an integer) returned (that is already set to close-on-exec), otherwise
2553returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
2554
2555Example: get a copy of standard error of another process and print soemthing to it.
2556
2557 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2558 or die "pidfd_getfd: $!\n";
2559 print $errfh "stderr\n";
2560
2561=item $fh = IO::AIO::eventfd [$initval, [$flags]]
2562
2563This is a direct interface to the Linux L<eventfd(2)> system call. The
2564(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
2565
2566On success, the new eventfd filehandle is returned, otherwise returns
2567C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
2568
2569Please refer to L<eventfd(2)> for more info on this call.
2570
2571The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
2572C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
2573
2574Example: create a new eventfd filehandle:
2575
2576 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2577 or die "eventfd: $!\n";
2578
2579=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
2580
2581This is a direct interface to the Linux L<timerfd_create(2)> system
2582call. The (unhelpful) default for C<$flags> is C<0>, but your default
2583should be C<IO::AIO::TFD_CLOEXEC>.
2584
2585On success, the new timerfd filehandle is returned, otherwise returns
2586C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
2587
2588Please refer to L<timerfd_create(2)> for more info on this call.
2589
2590The following C<$clockid> values are
2591available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
2592C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
2593C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
2594C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
2595
2596The following C<$flags> values are available (Linux
25972.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
2598
2599Example: create a new timerfd and set it to one-second repeated alarms,
2600then wait for two alarms:
2601
2602 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2603 or die "timerfd_create: $!\n";
2604
2605 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2606 or die "timerfd_settime: $!\n";
2607
2608 for (1..2) {
2609 8 == sysread $fh, my $buf, 8
2610 or die "timerfd read failure\n";
2611
2612 printf "number of expirations (likely 1): %d\n",
2613 unpack "Q", $buf;
2614 }
2615
2616=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
2617
2618This is a direct interface to the Linux L<timerfd_settime(2)> system
2619call. Please refer to its manpage for more info on this call.
2620
2621The new itimerspec is specified using two (possibly fractional) second
2622values, C<$new_interval> and C<$new_value>).
2623
2624On success, the current interval and value are returned (as per
2625C<timerfd_gettime>). On failure, the empty list is returned.
2626
2627The following C<$flags> values are
2628available: C<IO::AIO::TFD_TIMER_ABSTIME> and
2629C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
2630
2631See C<IO::AIO::timerfd_create> for a full example.
2632
2633=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2634
2635This is a direct interface to the Linux L<timerfd_gettime(2)> system
2636call. Please refer to its manpage for more info on this call.
2637
2638On success, returns the current values of interval and value for the given
2639timerfd (as potentially fractional second values). On failure, the empty
2640list is returned.
1892 2641
1893=back 2642=back
1894 2643
1895=cut 2644=cut
1896 2645
1962the process will result in undefined behaviour. Calling it at any time 2711the process will result in undefined behaviour. Calling it at any time
1963will also result in any undefined (by POSIX) behaviour. 2712will also result in any undefined (by POSIX) behaviour.
1964 2713
1965=back 2714=back
1966 2715
2716=head2 LINUX-SPECIFIC CALLS
2717
2718When a call is documented as "linux-specific" then this means it
2719originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
2720availability and compatibility of such calls regardless of the platform
2721it is compiled on, so platforms such as FreeBSD which often implement
2722these calls will work. When in doubt, call them and see if they fail wth
2723C<ENOSYS>.
2724
1967=head2 MEMORY USAGE 2725=head2 MEMORY USAGE
1968 2726
1969Per-request usage: 2727Per-request usage:
1970 2728
1971Each aio request uses - depending on your architecture - around 100-200 2729Each aio request uses - depending on your architecture - around 100-200
1983temporary buffers, and each thread requires a stack and other data 2741temporary buffers, and each thread requires a stack and other data
1984structures (usually around 16k-128k, depending on the OS). 2742structures (usually around 16k-128k, depending on the OS).
1985 2743
1986=head1 KNOWN BUGS 2744=head1 KNOWN BUGS
1987 2745
1988Known bugs will be fixed in the next release. 2746Known bugs will be fixed in the next release :)
2747
2748=head1 KNOWN ISSUES
2749
2750Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
2751or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
2752non-created hash slots or other scalars I didn't think of. It's best to
2753avoid such and either use scalar variables or making sure that the scalar
2754exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
2755
2756I am not sure anything can be done about this, so this is considered a
2757known issue, rather than a bug.
1989 2758
1990=head1 SEE ALSO 2759=head1 SEE ALSO
1991 2760
1992L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a 2761L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1993more natural syntax. 2762more natural syntax and L<IO::FDPass> for file descriptor passing.
1994 2763
1995=head1 AUTHOR 2764=head1 AUTHOR
1996 2765
1997 Marc Lehmann <schmorp@schmorp.de> 2766 Marc Lehmann <schmorp@schmorp.de>
1998 http://home.schmorp.de/ 2767 http://home.schmorp.de/

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