… | |
… | |
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 most of this works on all types of file descriptors (for example |
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67 | sockets), using these functions on file descriptors that support |
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68 | nonblocking operation (again, sockets, pipes etc.) is very inefficient or |
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69 | might not work (aio_read fails on sockets/pipes/fifos). Use an event loop |
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70 | for that (such as the L<Event|Event> module): IO::AIO will naturally fit |
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71 | into such an event loop itself. |
55 | |
72 | |
56 | In this version, a number of threads are started that execute your |
73 | In this version, a number of threads are started that execute your |
57 | requests and signal their completion. You don't need thread support |
74 | 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 |
75 | 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 |
76 | 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 |
77 | functions available on many operating systems. However, they are often |
61 | not well-supported or restricted (Linux doesn't allow them on normal |
78 | 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 |
79 | files currently, for example), and they would only support aio_read and |
63 | aio_write, so the remaining functionality would have to be implemented |
80 | aio_write, so the remaining functionality would have to be implemented |
64 | using threads anyway. |
81 | using threads anyway. |
65 | |
82 | |
66 | Although the module will work with in the presence of other (Perl-) |
83 | 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 |
84 | 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 |
85 | 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. |
86 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
70 | |
87 | |
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88 | =head2 EXAMPLE |
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89 | |
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90 | This is a simple example that uses the Event module and loads |
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91 | F</etc/passwd> asynchronously: |
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92 | |
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93 | use Fcntl; |
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94 | use Event; |
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95 | use IO::AIO; |
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96 | |
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97 | # register the IO::AIO callback with Event |
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98 | Event->io (fd => IO::AIO::poll_fileno, |
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99 | poll => 'r', |
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100 | cb => \&IO::AIO::poll_cb); |
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101 | |
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102 | # queue the request to open /etc/passwd |
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103 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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104 | my $fh = $_[0] |
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105 | or die "error while opening: $!"; |
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106 | |
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107 | # stat'ing filehandles is generally non-blocking |
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108 | my $size = -s $fh; |
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109 | |
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110 | # queue a request to read the file |
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111 | my $contents; |
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112 | aio_read $fh, 0, $size, $contents, 0, sub { |
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113 | $_[0] == $size |
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114 | or die "short read: $!"; |
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115 | |
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116 | close $fh; |
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117 | |
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118 | # file contents now in $contents |
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119 | print $contents; |
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120 | |
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121 | # exit event loop and program |
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122 | Event::unloop; |
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123 | }; |
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124 | }; |
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125 | |
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126 | # possibly queue up other requests, or open GUI windows, |
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127 | # check for sockets etc. etc. |
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128 | |
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129 | # process events as long as there are some: |
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130 | Event::loop; |
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131 | |
71 | =head1 REQUEST ANATOMY AND LIFETIME |
132 | =head1 REQUEST ANATOMY AND LIFETIME |
72 | |
133 | |
73 | Every C<aio_*> function creates a request. which is a C data structure not |
134 | Every C<aio_*> function creates a request. which is a C data structure not |
74 | directly visible to Perl. |
135 | directly visible to Perl. |
75 | |
136 | |
… | |
… | |
116 | Request has reached the end of its lifetime and holds no resources anymore |
177 | Request has reached the end of its lifetime and holds no resources anymore |
117 | (except possibly for the Perl object, but its connection to the actual |
178 | (except possibly for the Perl object, but its connection to the actual |
118 | aio request is severed and calling its methods will either do nothing or |
179 | aio request is severed and calling its methods will either do nothing or |
119 | result in a runtime error). |
180 | result in a runtime error). |
120 | |
181 | |
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182 | =back |
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183 | |
121 | =cut |
184 | =cut |
122 | |
185 | |
123 | package IO::AIO; |
186 | package IO::AIO; |
124 | |
187 | |
125 | no warnings; |
188 | no warnings; |
126 | use strict 'vars'; |
189 | use strict 'vars'; |
127 | |
190 | |
128 | use base 'Exporter'; |
191 | use base 'Exporter'; |
129 | |
192 | |
130 | BEGIN { |
193 | BEGIN { |
131 | our $VERSION = '2.0'; |
194 | our $VERSION = '2.2'; |
132 | |
195 | |
133 | our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
196 | 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 |
197 | 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 |
198 | aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link |
136 | aio_copy aio_group aio_nop aio_mknod); |
199 | aio_move aio_copy aio_group aio_nop aio_mknod); |
137 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
200 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
138 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
201 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
139 | min_parallel max_parallel nreqs nready npending); |
202 | min_parallel max_parallel max_idle |
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203 | nreqs nready npending nthreads |
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204 | max_poll_time max_poll_reqs); |
140 | |
205 | |
141 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
206 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
142 | |
207 | |
143 | require XSLoader; |
208 | require XSLoader; |
144 | XSLoader::load ("IO::AIO", $VERSION); |
209 | XSLoader::load ("IO::AIO", $VERSION); |
145 | } |
210 | } |
146 | |
211 | |
147 | =head1 FUNCTIONS |
212 | =head1 FUNCTIONS |
148 | |
213 | |
149 | =head2 AIO FUNCTIONS |
214 | =head2 AIO REQUEST FUNCTIONS |
150 | |
215 | |
151 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
216 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
152 | with the same name (sans C<aio_>). The arguments are similar or identical, |
217 | with the same name (sans C<aio_>). The arguments are similar or identical, |
153 | and they all accept an additional (and optional) C<$callback> argument |
218 | and they all accept an additional (and optional) C<$callback> argument |
154 | which must be a code reference. This code reference will get called with |
219 | which must be a code reference. This code reference will get called with |
… | |
… | |
157 | syscall has been executed asynchronously. |
222 | syscall has been executed asynchronously. |
158 | |
223 | |
159 | All functions expecting a filehandle keep a copy of the filehandle |
224 | All functions expecting a filehandle keep a copy of the filehandle |
160 | internally until the request has finished. |
225 | internally until the request has finished. |
161 | |
226 | |
162 | All requests return objects of type L<IO::AIO::REQ> that allow further |
227 | All functions return request objects of type L<IO::AIO::REQ> that allow |
163 | manipulation of those requests while they are in-flight. |
228 | further manipulation of those requests while they are in-flight. |
164 | |
229 | |
165 | The pathnames you pass to these routines I<must> be absolute and |
230 | The pathnames you pass to these routines I<must> be absolute and |
166 | encoded in byte form. The reason for the former is that at the time the |
231 | encoded as octets. The reason for the former is that at the time the |
167 | request is being executed, the current working directory could have |
232 | request is being executed, the current working directory could have |
168 | changed. Alternatively, you can make sure that you never change the |
233 | changed. Alternatively, you can make sure that you never change the |
169 | current working directory. |
234 | current working directory anywhere in the program and then use relative |
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235 | paths. |
170 | |
236 | |
171 | To encode pathnames to byte form, either make sure you either: a) |
237 | To encode pathnames as octets, either make sure you either: a) always pass |
172 | always pass in filenames you got from outside (command line, readdir |
238 | in filenames you got from outside (command line, readdir etc.) without |
173 | etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode |
239 | tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode |
174 | your pathnames to the locale (or other) encoding in effect in the user |
240 | your pathnames to the locale (or other) encoding in effect in the user |
175 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
241 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
176 | use something else. |
242 | use something else to ensure your scalar has the correct contents. |
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243 | |
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244 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
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245 | handles correctly wether it is set or not. |
177 | |
246 | |
178 | =over 4 |
247 | =over 4 |
179 | |
248 | |
180 | =item $prev_pri = aioreq_pri [$pri] |
249 | =item $prev_pri = aioreq_pri [$pri] |
181 | |
250 | |
… | |
… | |
204 | }; |
273 | }; |
205 | |
274 | |
206 | =item aioreq_nice $pri_adjust |
275 | =item aioreq_nice $pri_adjust |
207 | |
276 | |
208 | Similar to C<aioreq_pri>, but subtracts the given value from the current |
277 | Similar to C<aioreq_pri>, but subtracts the given value from the current |
209 | priority, so effects are cumulative. |
278 | priority, so the effect is cumulative. |
210 | |
279 | |
211 | =item aio_open $pathname, $flags, $mode, $callback->($fh) |
280 | =item aio_open $pathname, $flags, $mode, $callback->($fh) |
212 | |
281 | |
213 | Asynchronously open or create a file and call the callback with a newly |
282 | Asynchronously open or create a file and call the callback with a newly |
214 | created filehandle for the file. |
283 | created filehandle for the file. |
… | |
… | |
331 | Asynchronously unlink (delete) a file and call the callback with the |
400 | Asynchronously unlink (delete) a file and call the callback with the |
332 | result code. |
401 | result code. |
333 | |
402 | |
334 | =item aio_mknod $path, $mode, $dev, $callback->($status) |
403 | =item aio_mknod $path, $mode, $dev, $callback->($status) |
335 | |
404 | |
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405 | [EXPERIMENTAL] |
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406 | |
336 | Asynchronously create a device node (or fifo). See mknod(2): the only |
407 | Asynchronously create a device node (or fifo). See mknod(2). |
337 | portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0> |
408 | |
338 | for C<$dev>. |
409 | The only (POSIX-) portable way of calling this function is: |
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410 | |
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411 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
339 | |
412 | |
340 | =item aio_link $srcpath, $dstpath, $callback->($status) |
413 | =item aio_link $srcpath, $dstpath, $callback->($status) |
341 | |
414 | |
342 | Asynchronously create a new link to the existing object at C<$srcpath> at |
415 | Asynchronously create a new link to the existing object at C<$srcpath> at |
343 | the path C<$dstpath> and call the callback with the result code. |
416 | the path C<$dstpath> and call the callback with the result code. |
344 | |
417 | |
345 | =item aio_symlink $srcpath, $dstpath, $callback->($status) |
418 | =item aio_symlink $srcpath, $dstpath, $callback->($status) |
346 | |
419 | |
347 | Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
420 | Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
348 | the path C<$dstpath> and call the callback with the result code. |
421 | the path C<$dstpath> and call the callback with the result code. |
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422 | |
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423 | =item aio_readlink $path, $callback->($link) |
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424 | |
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425 | Asynchronously read the symlink specified by C<$path> and pass it to |
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426 | the callback. If an error occurs, nothing or undef gets passed to the |
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427 | callback. |
349 | |
428 | |
350 | =item aio_rename $srcpath, $dstpath, $callback->($status) |
429 | =item aio_rename $srcpath, $dstpath, $callback->($status) |
351 | |
430 | |
352 | Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
431 | Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
353 | rename(2) and call the callback with the result code. |
432 | rename(2) and call the callback with the result code. |
… | |
… | |
827 | |
906 | |
828 | =back |
907 | =back |
829 | |
908 | |
830 | =head2 SUPPORT FUNCTIONS |
909 | =head2 SUPPORT FUNCTIONS |
831 | |
910 | |
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911 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
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912 | |
832 | =over 4 |
913 | =over 4 |
833 | |
914 | |
834 | =item $fileno = IO::AIO::poll_fileno |
915 | =item $fileno = IO::AIO::poll_fileno |
835 | |
916 | |
836 | Return the I<request result pipe file descriptor>. This filehandle must be |
917 | Return the I<request result pipe file descriptor>. This filehandle must be |
… | |
… | |
840 | |
921 | |
841 | See C<poll_cb> for an example. |
922 | See C<poll_cb> for an example. |
842 | |
923 | |
843 | =item IO::AIO::poll_cb |
924 | =item IO::AIO::poll_cb |
844 | |
925 | |
845 | Process all outstanding events on the result pipe. You have to call this |
926 | Process some outstanding events on the result pipe. You have to call this |
846 | regularly. Returns the number of events processed. Returns immediately |
927 | regularly. Returns the number of events processed. Returns immediately |
847 | when no events are outstanding. |
928 | when no events are outstanding. The amount of events processed depends on |
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|
929 | the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. |
848 | |
930 | |
849 | If not all requests were processed for whatever reason, the filehandle |
931 | If not all requests were processed for whatever reason, the filehandle |
850 | will still be ready when C<poll_cb> returns. |
932 | will still be ready when C<poll_cb> returns. |
851 | |
933 | |
852 | Example: Install an Event watcher that automatically calls |
934 | Example: Install an Event watcher that automatically calls |
… | |
… | |
854 | |
936 | |
855 | Event->io (fd => IO::AIO::poll_fileno, |
937 | Event->io (fd => IO::AIO::poll_fileno, |
856 | poll => 'r', async => 1, |
938 | poll => 'r', async => 1, |
857 | cb => \&IO::AIO::poll_cb); |
939 | cb => \&IO::AIO::poll_cb); |
858 | |
940 | |
859 | =item IO::AIO::poll_some $max_requests |
941 | =item IO::AIO::max_poll_reqs $nreqs |
860 | |
942 | |
861 | Similar to C<poll_cb>, but only processes up to C<$max_requests> requests |
943 | =item IO::AIO::max_poll_time $seconds |
862 | at a time. |
|
|
863 | |
944 | |
864 | Useful if you want to ensure some level of interactiveness when perl is |
945 | These set the maximum number of requests (default C<0>, meaning infinity) |
865 | not fast enough to process all requests in time. |
946 | that are being processed by C<IO::AIO::poll_cb> in one call, respectively |
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947 | the maximum amount of time (default C<0>, meaning infinity) spent in |
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948 | C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount |
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949 | of time C<poll_cb> is allowed to use). |
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950 | |
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951 | Setting C<max_poll_time> to a non-zero value creates an overhead of one |
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952 | syscall per request processed, which is not normally a problem unless your |
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953 | callbacks are really really fast or your OS is really really slow (I am |
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954 | not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead. |
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955 | |
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956 | Setting these is useful if you want to ensure some level of |
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957 | interactiveness when perl is not fast enough to process all requests in |
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958 | time. |
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959 | |
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960 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
866 | |
961 | |
867 | Example: Install an Event watcher that automatically calls |
962 | Example: Install an Event watcher that automatically calls |
868 | IO::AIO::poll_some with low priority, to ensure that other parts of the |
963 | IO::AIO::poll_cb with low priority, to ensure that other parts of the |
869 | program get the CPU sometimes even under high AIO load. |
964 | program get the CPU sometimes even under high AIO load. |
870 | |
965 | |
|
|
966 | # try not to spend much more than 0.1s in poll_cb |
|
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967 | IO::AIO::max_poll_time 0.1; |
|
|
968 | |
|
|
969 | # use a low priority so other tasks have priority |
871 | Event->io (fd => IO::AIO::poll_fileno, |
970 | Event->io (fd => IO::AIO::poll_fileno, |
872 | poll => 'r', nice => 1, |
971 | poll => 'r', nice => 1, |
873 | cb => sub { IO::AIO::poll_some 256 }); |
972 | cb => &IO::AIO::poll_cb); |
874 | |
973 | |
875 | =item IO::AIO::poll_wait |
974 | =item IO::AIO::poll_wait |
876 | |
975 | |
|
|
976 | If there are any outstanding requests and none of them in the result |
877 | Wait till the result filehandle becomes ready for reading (simply does a |
977 | phase, wait till the result filehandle becomes ready for reading (simply |
878 | C<select> on the filehandle. This is useful if you want to synchronously wait |
978 | does a C<select> on the filehandle. This is useful if you want to |
879 | for some requests to finish). |
979 | synchronously wait for some requests to finish). |
880 | |
980 | |
881 | See C<nreqs> for an example. |
981 | See C<nreqs> for an example. |
882 | |
982 | |
|
|
983 | =item IO::AIO::poll |
|
|
984 | |
|
|
985 | Waits until some requests have been handled. |
|
|
986 | |
|
|
987 | Returns the number of requests processed, but is otherwise strictly |
|
|
988 | equivalent to: |
|
|
989 | |
|
|
990 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
991 | |
883 | =item IO::AIO::nreqs |
992 | =item IO::AIO::flush |
884 | |
993 | |
885 | Returns the number of requests currently in the ready, execute or pending |
994 | Wait till all outstanding AIO requests have been handled. |
886 | states (i.e. for which their callback has not been invoked yet). |
|
|
887 | |
995 | |
888 | Example: wait till there are no outstanding requests anymore: |
996 | Strictly equivalent to: |
889 | |
997 | |
890 | IO::AIO::poll_wait, IO::AIO::poll_cb |
998 | IO::AIO::poll_wait, IO::AIO::poll_cb |
891 | while IO::AIO::nreqs; |
999 | while IO::AIO::nreqs; |
892 | |
1000 | |
893 | =item IO::AIO::nready |
1001 | =head3 CONTROLLING THE NUMBER OF THREADS |
894 | |
|
|
895 | Returns the number of requests currently in the ready state (not yet |
|
|
896 | executed). |
|
|
897 | |
|
|
898 | =item IO::AIO::npending |
|
|
899 | |
|
|
900 | Returns the number of requests currently in the pending state (executed, |
|
|
901 | but not yet processed by poll_cb). |
|
|
902 | |
|
|
903 | =item IO::AIO::flush |
|
|
904 | |
|
|
905 | Wait till all outstanding AIO requests have been handled. |
|
|
906 | |
|
|
907 | Strictly equivalent to: |
|
|
908 | |
|
|
909 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
910 | while IO::AIO::nreqs; |
|
|
911 | |
|
|
912 | =item IO::AIO::poll |
|
|
913 | |
|
|
914 | Waits until some requests have been handled. |
|
|
915 | |
|
|
916 | Strictly equivalent to: |
|
|
917 | |
|
|
918 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
919 | if IO::AIO::nreqs; |
|
|
920 | |
1002 | |
921 | =item IO::AIO::min_parallel $nthreads |
1003 | =item IO::AIO::min_parallel $nthreads |
922 | |
1004 | |
923 | Set the minimum number of AIO threads to C<$nthreads>. The current |
1005 | Set the minimum number of AIO threads to C<$nthreads>. The current |
924 | default is C<8>, which means eight asynchronous operations can execute |
1006 | default is C<8>, which means eight asynchronous operations can execute |
925 | concurrently at any one time (the number of outstanding requests, |
1007 | concurrently at any one time (the number of outstanding requests, |
926 | however, is unlimited). |
1008 | however, is unlimited). |
927 | |
1009 | |
928 | IO::AIO starts threads only on demand, when an AIO request is queued and |
1010 | IO::AIO starts threads only on demand, when an AIO request is queued and |
929 | no free thread exists. |
1011 | no free thread exists. Please note that queueing up a hundred requests can |
|
|
1012 | create demand for a hundred threads, even if it turns out that everything |
|
|
1013 | is in the cache and could have been processed faster by a single thread. |
930 | |
1014 | |
931 | It is recommended to keep the number of threads relatively low, as some |
1015 | It is recommended to keep the number of threads relatively low, as some |
932 | Linux kernel versions will scale negatively with the number of threads |
1016 | Linux kernel versions will scale negatively with the number of threads |
933 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
1017 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
934 | versions, 4-32 threads should be fine. |
1018 | versions, 4-32 threads should be fine. |
… | |
… | |
948 | This module automatically runs C<max_parallel 0> at program end, to ensure |
1032 | This module automatically runs C<max_parallel 0> at program end, to ensure |
949 | that all threads are killed and that there are no outstanding requests. |
1033 | that all threads are killed and that there are no outstanding requests. |
950 | |
1034 | |
951 | Under normal circumstances you don't need to call this function. |
1035 | Under normal circumstances you don't need to call this function. |
952 | |
1036 | |
|
|
1037 | =item IO::AIO::max_idle $nthreads |
|
|
1038 | |
|
|
1039 | Limit the number of threads (default: 4) that are allowed to idle (i.e., |
|
|
1040 | threads that did not get a request to process within 10 seconds). That |
|
|
1041 | means if a thread becomes idle while C<$nthreads> other threads are also |
|
|
1042 | idle, it will free its resources and exit. |
|
|
1043 | |
|
|
1044 | This is useful when you allow a large number of threads (e.g. 100 or 1000) |
|
|
1045 | to allow for extremely high load situations, but want to free resources |
|
|
1046 | under normal circumstances (1000 threads can easily consume 30MB of RAM). |
|
|
1047 | |
|
|
1048 | The default is probably ok in most situations, especially if thread |
|
|
1049 | creation is fast. If thread creation is very slow on your system you might |
|
|
1050 | want to use larger values. |
|
|
1051 | |
953 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
1052 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
954 | |
1053 | |
955 | This is a very bad function to use in interactive programs because it |
1054 | This is a very bad function to use in interactive programs because it |
956 | blocks, and a bad way to reduce concurrency because it is inexact: Better |
1055 | blocks, and a bad way to reduce concurrency because it is inexact: Better |
957 | use an C<aio_group> together with a feed callback. |
1056 | use an C<aio_group> together with a feed callback. |
… | |
… | |
966 | |
1065 | |
967 | You can still queue as many requests as you want. Therefore, |
1066 | You can still queue as many requests as you want. Therefore, |
968 | C<max_oustsanding> is mainly useful in simple scripts (with low values) or |
1067 | C<max_oustsanding> is mainly useful in simple scripts (with low values) or |
969 | as a stop gap to shield against fatal memory overflow (with large values). |
1068 | as a stop gap to shield against fatal memory overflow (with large values). |
970 | |
1069 | |
|
|
1070 | =head3 STATISTICAL INFORMATION |
|
|
1071 | |
|
|
1072 | =item IO::AIO::nreqs |
|
|
1073 | |
|
|
1074 | Returns the number of requests currently in the ready, execute or pending |
|
|
1075 | states (i.e. for which their callback has not been invoked yet). |
|
|
1076 | |
|
|
1077 | Example: wait till there are no outstanding requests anymore: |
|
|
1078 | |
|
|
1079 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1080 | while IO::AIO::nreqs; |
|
|
1081 | |
|
|
1082 | =item IO::AIO::nready |
|
|
1083 | |
|
|
1084 | Returns the number of requests currently in the ready state (not yet |
|
|
1085 | executed). |
|
|
1086 | |
|
|
1087 | =item IO::AIO::npending |
|
|
1088 | |
|
|
1089 | Returns the number of requests currently in the pending state (executed, |
|
|
1090 | but not yet processed by poll_cb). |
|
|
1091 | |
971 | =back |
1092 | =back |
972 | |
1093 | |
973 | =cut |
1094 | =cut |
974 | |
1095 | |
975 | # support function to convert a fd into a perl filehandle |
1096 | # support function to convert a fd into a perl filehandle |
… | |
… | |
989 | } |
1110 | } |
990 | |
1111 | |
991 | min_parallel 8; |
1112 | min_parallel 8; |
992 | |
1113 | |
993 | END { |
1114 | END { |
|
|
1115 | min_parallel 1; |
994 | flush; |
1116 | flush; |
995 | }; |
1117 | }; |
996 | |
1118 | |
997 | 1; |
1119 | 1; |
998 | |
1120 | |