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50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
53 | This module implements asynchronous I/O using whatever means your |
53 | This module implements asynchronous I/O using whatever means your |
54 | operating system supports. |
54 | operating system supports. |
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55 | |
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56 | Asynchronous means that operations that can normally block your program |
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57 | (e.g. reading from disk) will be done asynchronously: the operation |
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58 | will still block, but you can do something else in the meantime. This |
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59 | is extremely useful for programs that need to stay interactive even |
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60 | when doing heavy I/O (GUI programs, high performance network servers |
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61 | etc.), but can also be used to easily do operations in parallel that are |
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62 | normally done sequentially, e.g. stat'ing many files, which is much faster |
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63 | on a RAID volume or over NFS when you do a number of stat operations |
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64 | concurrently. |
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65 | |
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66 | While this works on all types of file descriptors (for example sockets), |
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67 | using these functions on file descriptors that support nonblocking |
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68 | operation (again, sockets, pipes etc.) is very inefficient. Use an event |
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69 | loop for that (such as the L<Event|Event> module): IO::AIO will naturally |
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70 | fit into such an event loop itself. |
55 | |
71 | |
56 | In this version, a number of threads are started that execute your |
72 | In this version, a number of threads are started that execute your |
57 | requests and signal their completion. You don't need thread support |
73 | requests and signal their completion. You don't need thread support |
58 | in perl, and the threads created by this module will not be visible |
74 | in perl, and the threads created by this module will not be visible |
59 | to perl. In the future, this module might make use of the native aio |
75 | to perl. In the future, this module might make use of the native aio |
60 | functions available on many operating systems. However, they are often |
76 | functions available on many operating systems. However, they are often |
61 | not well-supported or restricted (Linux doesn't allow them on normal |
77 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
62 | files currently, for example), and they would only support aio_read and |
78 | files currently, for example), and they would only support aio_read and |
63 | aio_write, so the remaining functionality would have to be implemented |
79 | aio_write, so the remaining functionality would have to be implemented |
64 | using threads anyway. |
80 | using threads anyway. |
65 | |
81 | |
66 | Although the module will work with in the presence of other (Perl-) |
82 | Although the module will work with in the presence of other (Perl-) |
67 | threads, it is currently not reentrant in any way, so use appropriate |
83 | threads, it is currently not reentrant in any way, so use appropriate |
68 | locking yourself, always call C<poll_cb> from within the same thread, or |
84 | locking yourself, always call C<poll_cb> from within the same thread, or |
69 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
85 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
70 | |
86 | |
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87 | =head2 EXAMPLE |
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88 | |
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89 | This is a simple example that uses the Event module and loads |
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90 | F</etc/passwd> asynchronously: |
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91 | |
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92 | use Fcntl; |
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93 | use Event; |
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94 | use IO::AIO; |
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95 | |
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96 | # register the IO::AIO callback with Event |
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97 | Event->io (fd => IO::AIO::poll_fileno, |
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98 | poll => 'r', |
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99 | cb => \&IO::AIO::poll_cb); |
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100 | |
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101 | # queue the request to open /etc/passwd |
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102 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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103 | my $fh = $_[0] |
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104 | or die "error while opening: $!"; |
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105 | |
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106 | # stat'ing filehandles is generally non-blocking |
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107 | my $size = -s $fh; |
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108 | |
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109 | # queue a request to read the file |
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110 | my $contents; |
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111 | aio_read $fh, 0, $size, $contents, 0, sub { |
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112 | $_[0] == $size |
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113 | or die "short read: $!"; |
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114 | |
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115 | close $fh; |
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116 | |
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117 | # file contents now in $contents |
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118 | print $contents; |
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119 | |
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120 | # exit event loop and program |
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121 | Event::unloop; |
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122 | }; |
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123 | }; |
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124 | |
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125 | # possibly queue up other requests, or open GUI windows, |
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126 | # check for sockets etc. etc. |
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127 | |
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128 | # process events as long as there are some: |
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129 | Event::loop; |
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130 | |
71 | =head1 REQUEST ANATOMY AND LIFETIME |
131 | =head1 REQUEST ANATOMY AND LIFETIME |
72 | |
132 | |
73 | Every C<aio_*> function creates a request. which is a C data structure not |
133 | Every C<aio_*> function creates a request. which is a C data structure not |
74 | directly visible to Perl. |
134 | directly visible to Perl. |
75 | |
135 | |
… | |
… | |
126 | use strict 'vars'; |
186 | use strict 'vars'; |
127 | |
187 | |
128 | use base 'Exporter'; |
188 | use base 'Exporter'; |
129 | |
189 | |
130 | BEGIN { |
190 | BEGIN { |
131 | our $VERSION = '2.0'; |
191 | our $VERSION = '2.1'; |
132 | |
192 | |
133 | our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
193 | our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
134 | aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink |
194 | aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink |
135 | aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move |
195 | aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move |
136 | aio_group aio_nop); |
196 | aio_copy aio_group aio_nop aio_mknod); |
137 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
197 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
138 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
198 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
139 | min_parallel max_parallel nreqs); |
199 | min_parallel max_parallel max_idle |
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200 | nreqs nready npending nthreads |
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201 | max_poll_time max_poll_reqs); |
140 | |
202 | |
141 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
203 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
142 | |
204 | |
143 | require XSLoader; |
205 | require XSLoader; |
144 | XSLoader::load ("IO::AIO", $VERSION); |
206 | XSLoader::load ("IO::AIO", $VERSION); |
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… | |
175 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
237 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
176 | use something else. |
238 | use something else. |
177 | |
239 | |
178 | =over 4 |
240 | =over 4 |
179 | |
241 | |
180 | =item aioreq_pri $pri |
242 | =item $prev_pri = aioreq_pri [$pri] |
181 | |
243 | |
182 | Sets the priority for the next aio request. The default priority |
244 | Returns the priority value that would be used for the next request and, if |
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245 | C<$pri> is given, sets the priority for the next aio request. |
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246 | |
183 | is C<0>, the minimum and maximum priorities are C<-4> and C<4>, |
247 | The default priority is C<0>, the minimum and maximum priorities are C<-4> |
184 | respectively. Requests with higher priority will be serviced first. |
248 | and C<4>, respectively. Requests with higher priority will be serviced |
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249 | first. |
185 | |
250 | |
186 | The priority will be reset to C<0> after each call to one of the C<aio_> |
251 | The priority will be reset to C<0> after each call to one of the C<aio_*> |
187 | functions. |
252 | functions. |
188 | |
253 | |
189 | Example: open a file with low priority, then read something from it with |
254 | Example: open a file with low priority, then read something from it with |
190 | higher priority so the read request is serviced before other low priority |
255 | higher priority so the read request is serviced before other low priority |
191 | open requests (potentially spamming the cache): |
256 | open requests (potentially spamming the cache): |
… | |
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261 | |
326 | |
262 | aio_read $fh, 7, 15, $buffer, 0, sub { |
327 | aio_read $fh, 7, 15, $buffer, 0, sub { |
263 | $_[0] > 0 or die "read error: $!"; |
328 | $_[0] > 0 or die "read error: $!"; |
264 | print "read $_[0] bytes: <$buffer>\n"; |
329 | print "read $_[0] bytes: <$buffer>\n"; |
265 | }; |
330 | }; |
266 | |
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267 | =item aio_move $srcpath, $dstpath, $callback->($status) |
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268 | |
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269 | Try to move the I<file> (directories not supported as either source or |
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270 | destination) from C<$srcpath> to C<$dstpath> and call the callback with |
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271 | the C<0> (error) or C<-1> ok. |
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272 | |
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273 | This is a composite request that tries to rename(2) the file first. If |
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274 | rename files with C<EXDEV>, it creates the destination file with mode 0200 |
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275 | and copies the contents of the source file into it using C<aio_sendfile>, |
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276 | followed by restoring atime, mtime, access mode and uid/gid, in that |
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277 | order, and unlinking the C<$srcpath>. |
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278 | |
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279 | If an error occurs, the partial destination file will be unlinked, if |
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280 | possible, except when setting atime, mtime, access mode and uid/gid, where |
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281 | errors are being ignored. |
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282 | |
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283 | =cut |
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284 | |
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285 | sub aio_move($$$) { |
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286 | my ($src, $dst, $cb) = @_; |
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287 | |
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288 | my $grp = aio_group $cb; |
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289 | |
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290 | add $grp aio_rename $src, $dst, sub { |
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291 | if ($_[0] && $! == EXDEV) { |
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292 | add $grp aio_open $src, O_RDONLY, 0, sub { |
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293 | if (my $src_fh = $_[0]) { |
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294 | my @stat = stat $src_fh; |
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295 | |
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296 | add $grp aio_open $dst, O_WRONLY, 0200, sub { |
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297 | if (my $dst_fh = $_[0]) { |
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298 | add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
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299 | close $src_fh; |
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300 | |
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301 | if ($_[0] == $stat[7]) { |
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302 | utime $stat[8], $stat[9], $dst; |
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303 | chmod $stat[2] & 07777, $dst_fh; |
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304 | chown $stat[4], $stat[5], $dst_fh; |
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305 | close $dst_fh; |
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306 | |
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307 | add $grp aio_unlink $src, sub { |
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308 | $grp->result ($_[0]); |
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309 | }; |
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310 | } else { |
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311 | my $errno = $!; |
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312 | add $grp aio_unlink $dst, sub { |
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313 | $! = $errno; |
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314 | $grp->result (-1); |
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315 | }; |
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316 | } |
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317 | }; |
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318 | } else { |
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319 | $grp->result (-1); |
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320 | } |
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321 | }, |
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322 | |
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323 | } else { |
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324 | $grp->result (-1); |
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325 | } |
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326 | }; |
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327 | } else { |
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328 | $grp->result ($_[0]); |
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329 | } |
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330 | }; |
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331 | |
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332 | $grp |
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333 | } |
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334 | |
331 | |
335 | =item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
332 | =item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
336 | |
333 | |
337 | Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
334 | Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
338 | reading at byte offset C<$in_offset>, and starts writing at the current |
335 | reading at byte offset C<$in_offset>, and starts writing at the current |
… | |
… | |
394 | =item aio_unlink $pathname, $callback->($status) |
391 | =item aio_unlink $pathname, $callback->($status) |
395 | |
392 | |
396 | Asynchronously unlink (delete) a file and call the callback with the |
393 | Asynchronously unlink (delete) a file and call the callback with the |
397 | result code. |
394 | result code. |
398 | |
395 | |
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396 | =item aio_mknod $path, $mode, $dev, $callback->($status) |
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397 | |
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398 | [EXPERIMENTAL] |
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399 | |
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400 | Asynchronously create a device node (or fifo). See mknod(2). |
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401 | |
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402 | The only (POSIX-) portable way of calling this function is: |
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403 | |
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404 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
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405 | |
399 | =item aio_link $srcpath, $dstpath, $callback->($status) |
406 | =item aio_link $srcpath, $dstpath, $callback->($status) |
400 | |
407 | |
401 | Asynchronously create a new link to the existing object at C<$srcpath> at |
408 | Asynchronously create a new link to the existing object at C<$srcpath> at |
402 | the path C<$dstpath> and call the callback with the result code. |
409 | the path C<$dstpath> and call the callback with the result code. |
403 | |
410 | |
… | |
… | |
422 | directory (i.e. opendir + readdir + closedir). The entries will not be |
429 | directory (i.e. opendir + readdir + closedir). The entries will not be |
423 | sorted, and will B<NOT> include the C<.> and C<..> entries. |
430 | sorted, and will B<NOT> include the C<.> and C<..> entries. |
424 | |
431 | |
425 | The callback a single argument which is either C<undef> or an array-ref |
432 | The callback a single argument which is either C<undef> or an array-ref |
426 | with the filenames. |
433 | with the filenames. |
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434 | |
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435 | =item aio_copy $srcpath, $dstpath, $callback->($status) |
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436 | |
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437 | Try to copy the I<file> (directories not supported as either source or |
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438 | destination) from C<$srcpath> to C<$dstpath> and call the callback with |
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439 | the C<0> (error) or C<-1> ok. |
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440 | |
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441 | This is a composite request that it creates the destination file with |
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442 | mode 0200 and copies the contents of the source file into it using |
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443 | C<aio_sendfile>, followed by restoring atime, mtime, access mode and |
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444 | uid/gid, in that order. |
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445 | |
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446 | If an error occurs, the partial destination file will be unlinked, if |
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447 | possible, except when setting atime, mtime, access mode and uid/gid, where |
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448 | errors are being ignored. |
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449 | |
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450 | =cut |
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451 | |
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452 | sub aio_copy($$;$) { |
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453 | my ($src, $dst, $cb) = @_; |
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454 | |
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455 | my $pri = aioreq_pri; |
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456 | my $grp = aio_group $cb; |
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457 | |
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458 | aioreq_pri $pri; |
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459 | add $grp aio_open $src, O_RDONLY, 0, sub { |
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460 | if (my $src_fh = $_[0]) { |
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461 | my @stat = stat $src_fh; |
|
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462 | |
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463 | aioreq_pri $pri; |
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464 | add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { |
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465 | if (my $dst_fh = $_[0]) { |
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466 | aioreq_pri $pri; |
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467 | add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
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468 | if ($_[0] == $stat[7]) { |
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469 | $grp->result (0); |
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470 | close $src_fh; |
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471 | |
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472 | # those should not normally block. should. should. |
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473 | utime $stat[8], $stat[9], $dst; |
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474 | chmod $stat[2] & 07777, $dst_fh; |
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475 | chown $stat[4], $stat[5], $dst_fh; |
|
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476 | close $dst_fh; |
|
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477 | } else { |
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478 | $grp->result (-1); |
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479 | close $src_fh; |
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480 | close $dst_fh; |
|
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481 | |
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482 | aioreq $pri; |
|
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483 | add $grp aio_unlink $dst; |
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484 | } |
|
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485 | }; |
|
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486 | } else { |
|
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487 | $grp->result (-1); |
|
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488 | } |
|
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489 | }, |
|
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490 | |
|
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491 | } else { |
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492 | $grp->result (-1); |
|
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493 | } |
|
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494 | }; |
|
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495 | |
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496 | $grp |
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497 | } |
|
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498 | |
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499 | =item aio_move $srcpath, $dstpath, $callback->($status) |
|
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500 | |
|
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501 | Try to move the I<file> (directories not supported as either source or |
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502 | destination) from C<$srcpath> to C<$dstpath> and call the callback with |
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503 | the C<0> (error) or C<-1> ok. |
|
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504 | |
|
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505 | This is a composite request that tries to rename(2) the file first. If |
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506 | rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if |
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507 | that is successful, unlinking the C<$srcpath>. |
|
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508 | |
|
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509 | =cut |
|
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510 | |
|
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511 | sub aio_move($$;$) { |
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512 | my ($src, $dst, $cb) = @_; |
|
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513 | |
|
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514 | my $pri = aioreq_pri; |
|
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515 | my $grp = aio_group $cb; |
|
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516 | |
|
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517 | aioreq_pri $pri; |
|
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518 | add $grp aio_rename $src, $dst, sub { |
|
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519 | if ($_[0] && $! == EXDEV) { |
|
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520 | aioreq_pri $pri; |
|
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521 | add $grp aio_copy $src, $dst, sub { |
|
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522 | $grp->result ($_[0]); |
|
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523 | |
|
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524 | if (!$_[0]) { |
|
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525 | aioreq_pri $pri; |
|
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526 | add $grp aio_unlink $src; |
|
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527 | } |
|
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528 | }; |
|
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529 | } else { |
|
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530 | $grp->result ($_[0]); |
|
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531 | } |
|
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532 | }; |
|
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533 | |
|
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534 | $grp |
|
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535 | } |
427 | |
536 | |
428 | =item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
537 | =item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
429 | |
538 | |
430 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
539 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
431 | efficiently separate the entries of directory C<$path> into two sets of |
540 | efficiently separate the entries of directory C<$path> into two sets of |
… | |
… | |
433 | recurse into (everything else, including symlinks to directories). |
542 | recurse into (everything else, including symlinks to directories). |
434 | |
543 | |
435 | C<aio_scandir> is a composite request that creates of many sub requests_ |
544 | C<aio_scandir> is a composite request that creates of many sub requests_ |
436 | C<$maxreq> specifies the maximum number of outstanding aio requests that |
545 | C<$maxreq> specifies the maximum number of outstanding aio requests that |
437 | this function generates. If it is C<< <= 0 >>, then a suitable default |
546 | this function generates. If it is C<< <= 0 >>, then a suitable default |
438 | will be chosen (currently 6). |
547 | will be chosen (currently 4). |
439 | |
548 | |
440 | On error, the callback is called without arguments, otherwise it receives |
549 | On error, the callback is called without arguments, otherwise it receives |
441 | two array-refs with path-relative entry names. |
550 | two array-refs with path-relative entry names. |
442 | |
551 | |
443 | Example: |
552 | Example: |
… | |
… | |
480 | =cut |
589 | =cut |
481 | |
590 | |
482 | sub aio_scandir($$$) { |
591 | sub aio_scandir($$$) { |
483 | my ($path, $maxreq, $cb) = @_; |
592 | my ($path, $maxreq, $cb) = @_; |
484 | |
593 | |
|
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594 | my $pri = aioreq_pri; |
|
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595 | |
485 | my $grp = aio_group $cb; |
596 | my $grp = aio_group $cb; |
486 | |
597 | |
487 | $maxreq = 6 if $maxreq <= 0; |
598 | $maxreq = 4 if $maxreq <= 0; |
488 | |
599 | |
489 | # stat once |
600 | # stat once |
|
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601 | aioreq_pri $pri; |
490 | add $grp aio_stat $path, sub { |
602 | add $grp aio_stat $path, sub { |
491 | return $grp->result () if $_[0]; |
603 | return $grp->result () if $_[0]; |
492 | my $now = time; |
604 | my $now = time; |
493 | my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
605 | my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
494 | |
606 | |
495 | # read the directory entries |
607 | # read the directory entries |
|
|
608 | aioreq_pri $pri; |
496 | add $grp aio_readdir $path, sub { |
609 | add $grp aio_readdir $path, sub { |
497 | my $entries = shift |
610 | my $entries = shift |
498 | or return $grp->result (); |
611 | or return $grp->result (); |
499 | |
612 | |
500 | # stat the dir another time |
613 | # stat the dir another time |
|
|
614 | aioreq_pri $pri; |
501 | add $grp aio_stat $path, sub { |
615 | add $grp aio_stat $path, sub { |
502 | my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
616 | my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
503 | |
617 | |
504 | my $ndirs; |
618 | my $ndirs; |
505 | |
619 | |
… | |
… | |
529 | limit $statgrp $maxreq; |
643 | limit $statgrp $maxreq; |
530 | feed $statgrp sub { |
644 | feed $statgrp sub { |
531 | return unless @$entries; |
645 | return unless @$entries; |
532 | my $entry = pop @$entries; |
646 | my $entry = pop @$entries; |
533 | |
647 | |
|
|
648 | aioreq_pri $pri; |
534 | add $statgrp aio_stat "$path/$entry/.", sub { |
649 | add $statgrp aio_stat "$path/$entry/.", sub { |
535 | if ($_[0] < 0) { |
650 | if ($_[0] < 0) { |
536 | push @nondirs, $entry; |
651 | push @nondirs, $entry; |
537 | } else { |
652 | } else { |
538 | # need to check for real directory |
653 | # need to check for real directory |
|
|
654 | aioreq_pri $pri; |
539 | add $statgrp aio_lstat "$path/$entry", sub { |
655 | add $statgrp aio_lstat "$path/$entry", sub { |
540 | if (-d _) { |
656 | if (-d _) { |
541 | push @dirs, $entry; |
657 | push @dirs, $entry; |
542 | |
658 | |
543 | unless (--$ndirs) { |
659 | unless (--$ndirs) { |
… | |
… | |
714 | itself. Useful when you queued a lot of events but got a result early. |
830 | itself. Useful when you queued a lot of events but got a result early. |
715 | |
831 | |
716 | =item $grp->result (...) |
832 | =item $grp->result (...) |
717 | |
833 | |
718 | Set the result value(s) that will be passed to the group callback when all |
834 | Set the result value(s) that will be passed to the group callback when all |
719 | subrequests have finished. By default, no argument will be passed. |
835 | subrequests have finished and set thre groups errno to the current value |
|
|
836 | of errno (just like calling C<errno> without an error number). By default, |
|
|
837 | no argument will be passed and errno is zero. |
|
|
838 | |
|
|
839 | =item $grp->errno ([$errno]) |
|
|
840 | |
|
|
841 | Sets the group errno value to C<$errno>, or the current value of errno |
|
|
842 | when the argument is missing. |
|
|
843 | |
|
|
844 | Every aio request has an associated errno value that is restored when |
|
|
845 | the callback is invoked. This method lets you change this value from its |
|
|
846 | default (0). |
|
|
847 | |
|
|
848 | Calling C<result> will also set errno, so make sure you either set C<$!> |
|
|
849 | before the call to C<result>, or call c<errno> after it. |
720 | |
850 | |
721 | =item feed $grp $callback->($grp) |
851 | =item feed $grp $callback->($grp) |
722 | |
852 | |
723 | Sets a feeder/generator on this group: every group can have an attached |
853 | Sets a feeder/generator on this group: every group can have an attached |
724 | generator that generates requests if idle. The idea behind this is that, |
854 | generator that generates requests if idle. The idea behind this is that, |
… | |
… | |
763 | |
893 | |
764 | =back |
894 | =back |
765 | |
895 | |
766 | =head2 SUPPORT FUNCTIONS |
896 | =head2 SUPPORT FUNCTIONS |
767 | |
897 | |
|
|
898 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
|
|
899 | |
768 | =over 4 |
900 | =over 4 |
769 | |
901 | |
770 | =item $fileno = IO::AIO::poll_fileno |
902 | =item $fileno = IO::AIO::poll_fileno |
771 | |
903 | |
772 | Return the I<request result pipe file descriptor>. This filehandle must be |
904 | Return the I<request result pipe file descriptor>. This filehandle must be |
… | |
… | |
776 | |
908 | |
777 | See C<poll_cb> for an example. |
909 | See C<poll_cb> for an example. |
778 | |
910 | |
779 | =item IO::AIO::poll_cb |
911 | =item IO::AIO::poll_cb |
780 | |
912 | |
781 | Process all outstanding events on the result pipe. You have to call this |
913 | Process some outstanding events on the result pipe. You have to call this |
782 | regularly. Returns the number of events processed. Returns immediately |
914 | regularly. Returns the number of events processed. Returns immediately |
783 | when no events are outstanding. |
915 | when no events are outstanding. The amount of events processed depends on |
|
|
916 | the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. |
784 | |
917 | |
785 | If not all requests were processed for whatever reason, the filehandle |
918 | If not all requests were processed for whatever reason, the filehandle |
786 | will still be ready when C<poll_cb> returns. |
919 | will still be ready when C<poll_cb> returns. |
787 | |
920 | |
788 | Example: Install an Event watcher that automatically calls |
921 | Example: Install an Event watcher that automatically calls |
… | |
… | |
790 | |
923 | |
791 | Event->io (fd => IO::AIO::poll_fileno, |
924 | Event->io (fd => IO::AIO::poll_fileno, |
792 | poll => 'r', async => 1, |
925 | poll => 'r', async => 1, |
793 | cb => \&IO::AIO::poll_cb); |
926 | cb => \&IO::AIO::poll_cb); |
794 | |
927 | |
795 | =item IO::AIO::poll_some $max_requests |
928 | =item IO::AIO::max_poll_reqs $nreqs |
796 | |
929 | |
797 | Similar to C<poll_cb>, but only processes up to C<$max_requests> requests |
930 | =item IO::AIO::max_poll_time $seconds |
798 | at a time. |
|
|
799 | |
931 | |
800 | Useful if you want to ensure some level of interactiveness when perl is |
932 | These set the maximum number of requests (default C<0>, meaning infinity) |
801 | not fast enough to process all requests in time. |
933 | that are being processed by C<IO::AIO::poll_cb> in one call, respectively |
|
|
934 | the maximum amount of time (default C<0>, meaning infinity) spent in |
|
|
935 | C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount |
|
|
936 | of time C<poll_cb> is allowed to use). |
|
|
937 | |
|
|
938 | Setting these is useful if you want to ensure some level of |
|
|
939 | interactiveness when perl is not fast enough to process all requests in |
|
|
940 | time. |
|
|
941 | |
|
|
942 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
802 | |
943 | |
803 | Example: Install an Event watcher that automatically calls |
944 | Example: Install an Event watcher that automatically calls |
804 | IO::AIO::poll_some with low priority, to ensure that other parts of the |
945 | IO::AIO::poll_some with low priority, to ensure that other parts of the |
805 | program get the CPU sometimes even under high AIO load. |
946 | program get the CPU sometimes even under high AIO load. |
806 | |
947 | |
|
|
948 | # try not to spend much more than 0.1s in poll_cb |
|
|
949 | IO::AIO::max_poll_time 0.1; |
|
|
950 | |
|
|
951 | # use a low priority so other tasks have priority |
807 | Event->io (fd => IO::AIO::poll_fileno, |
952 | Event->io (fd => IO::AIO::poll_fileno, |
808 | poll => 'r', nice => 1, |
953 | poll => 'r', nice => 1, |
809 | cb => sub { IO::AIO::poll_some 256 }); |
954 | cb => &IO::AIO::poll_cb); |
810 | |
955 | |
811 | =item IO::AIO::poll_wait |
956 | =item IO::AIO::poll_wait |
812 | |
957 | |
813 | Wait till the result filehandle becomes ready for reading (simply does a |
958 | Wait till the result filehandle becomes ready for reading (simply does a |
814 | C<select> on the filehandle. This is useful if you want to synchronously wait |
959 | C<select> on the filehandle. This is useful if you want to synchronously |
815 | for some requests to finish). |
960 | wait for some requests to finish). |
816 | |
961 | |
817 | See C<nreqs> for an example. |
962 | See C<nreqs> for an example. |
818 | |
963 | |
|
|
964 | =item IO::AIO::poll |
|
|
965 | |
|
|
966 | Waits until some requests have been handled. |
|
|
967 | |
|
|
968 | Strictly equivalent to: |
|
|
969 | |
|
|
970 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
971 | if IO::AIO::nreqs; |
|
|
972 | |
819 | =item IO::AIO::nreqs |
973 | =item IO::AIO::flush |
820 | |
974 | |
821 | Returns the number of requests currently outstanding (i.e. for which their |
975 | Wait till all outstanding AIO requests have been handled. |
822 | callback has not been invoked yet). |
|
|
823 | |
976 | |
824 | Example: wait till there are no outstanding requests anymore: |
977 | Strictly equivalent to: |
825 | |
978 | |
826 | IO::AIO::poll_wait, IO::AIO::poll_cb |
979 | IO::AIO::poll_wait, IO::AIO::poll_cb |
827 | while IO::AIO::nreqs; |
980 | while IO::AIO::nreqs; |
828 | |
981 | |
829 | =item IO::AIO::flush |
982 | =head3 CONTROLLING THE NUMBER OF THREADS |
830 | |
|
|
831 | Wait till all outstanding AIO requests have been handled. |
|
|
832 | |
|
|
833 | Strictly equivalent to: |
|
|
834 | |
|
|
835 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
836 | while IO::AIO::nreqs; |
|
|
837 | |
|
|
838 | =item IO::AIO::poll |
|
|
839 | |
|
|
840 | Waits until some requests have been handled. |
|
|
841 | |
|
|
842 | Strictly equivalent to: |
|
|
843 | |
|
|
844 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
845 | if IO::AIO::nreqs; |
|
|
846 | |
983 | |
847 | =item IO::AIO::min_parallel $nthreads |
984 | =item IO::AIO::min_parallel $nthreads |
848 | |
985 | |
849 | Set the minimum number of AIO threads to C<$nthreads>. The current |
986 | Set the minimum number of AIO threads to C<$nthreads>. The current |
850 | default is C<8>, which means eight asynchronous operations can execute |
987 | default is C<8>, which means eight asynchronous operations can execute |
851 | concurrently at any one time (the number of outstanding requests, |
988 | concurrently at any one time (the number of outstanding requests, |
852 | however, is unlimited). |
989 | however, is unlimited). |
853 | |
990 | |
854 | IO::AIO starts threads only on demand, when an AIO request is queued and |
991 | IO::AIO starts threads only on demand, when an AIO request is queued and |
855 | no free thread exists. |
992 | no free thread exists. Please note that queueing up a hundred requests can |
|
|
993 | create demand for a hundred threads, even if it turns out that everything |
|
|
994 | is in the cache and could have been processed faster by a single thread. |
856 | |
995 | |
857 | It is recommended to keep the number of threads relatively low, as some |
996 | It is recommended to keep the number of threads relatively low, as some |
858 | Linux kernel versions will scale negatively with the number of threads |
997 | Linux kernel versions will scale negatively with the number of threads |
859 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
998 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
860 | versions, 4-32 threads should be fine. |
999 | versions, 4-32 threads should be fine. |
… | |
… | |
874 | This module automatically runs C<max_parallel 0> at program end, to ensure |
1013 | This module automatically runs C<max_parallel 0> at program end, to ensure |
875 | that all threads are killed and that there are no outstanding requests. |
1014 | that all threads are killed and that there are no outstanding requests. |
876 | |
1015 | |
877 | Under normal circumstances you don't need to call this function. |
1016 | Under normal circumstances you don't need to call this function. |
878 | |
1017 | |
|
|
1018 | =item IO::AIO::max_idle $nthreads |
|
|
1019 | |
|
|
1020 | Limit the number of threads (default: 4) that are allowed to idle (i.e., |
|
|
1021 | threads that did not get a request to process within 10 seconds). That |
|
|
1022 | means if a thread becomes idle while C<$nthreads> other threads are also |
|
|
1023 | idle, it will free its resources and exit. |
|
|
1024 | |
|
|
1025 | This is useful when you allow a large number of threads (e.g. 100 or 1000) |
|
|
1026 | to allow for extremely high load situations, but want to free resources |
|
|
1027 | under normal circumstances (1000 threads can easily consume 30MB of RAM). |
|
|
1028 | |
|
|
1029 | The default is probably ok in most situations, especially if thread |
|
|
1030 | creation is fast. If thread creation is very slow on your system you might |
|
|
1031 | want to use larger values. |
|
|
1032 | |
879 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
1033 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
880 | |
1034 | |
881 | This is a very bad function to use in interactive programs because it |
1035 | This is a very bad function to use in interactive programs because it |
882 | blocks, and a bad way to reduce concurrency because it is inexact: Better |
1036 | blocks, and a bad way to reduce concurrency because it is inexact: Better |
883 | use an C<aio_group> together with a feed callback. |
1037 | use an C<aio_group> together with a feed callback. |
… | |
… | |
892 | |
1046 | |
893 | You can still queue as many requests as you want. Therefore, |
1047 | You can still queue as many requests as you want. Therefore, |
894 | C<max_oustsanding> is mainly useful in simple scripts (with low values) or |
1048 | C<max_oustsanding> is mainly useful in simple scripts (with low values) or |
895 | as a stop gap to shield against fatal memory overflow (with large values). |
1049 | as a stop gap to shield against fatal memory overflow (with large values). |
896 | |
1050 | |
|
|
1051 | =head3 STATISTICAL INFORMATION |
|
|
1052 | |
|
|
1053 | =item IO::AIO::nreqs |
|
|
1054 | |
|
|
1055 | Returns the number of requests currently in the ready, execute or pending |
|
|
1056 | states (i.e. for which their callback has not been invoked yet). |
|
|
1057 | |
|
|
1058 | Example: wait till there are no outstanding requests anymore: |
|
|
1059 | |
|
|
1060 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1061 | while IO::AIO::nreqs; |
|
|
1062 | |
|
|
1063 | =item IO::AIO::nready |
|
|
1064 | |
|
|
1065 | Returns the number of requests currently in the ready state (not yet |
|
|
1066 | executed). |
|
|
1067 | |
|
|
1068 | =item IO::AIO::npending |
|
|
1069 | |
|
|
1070 | Returns the number of requests currently in the pending state (executed, |
|
|
1071 | but not yet processed by poll_cb). |
|
|
1072 | |
897 | =back |
1073 | =back |
898 | |
1074 | |
899 | =cut |
1075 | =cut |
900 | |
1076 | |
901 | # support function to convert a fd into a perl filehandle |
1077 | # support function to convert a fd into a perl filehandle |
… | |
… | |
915 | } |
1091 | } |
916 | |
1092 | |
917 | min_parallel 8; |
1093 | min_parallel 8; |
918 | |
1094 | |
919 | END { |
1095 | END { |
920 | max_parallel 0; |
1096 | min_parallel 1; |
921 | } |
1097 | flush; |
|
|
1098 | }; |
922 | |
1099 | |
923 | 1; |
1100 | 1; |
924 | |
1101 | |
925 | =head2 FORK BEHAVIOUR |
1102 | =head2 FORK BEHAVIOUR |
926 | |
1103 | |