… | |
… | |
82 | 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-) |
83 | 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 |
84 | 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 |
85 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
85 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
86 | |
86 | |
|
|
87 | =head2 EXAMPLE |
|
|
88 | |
|
|
89 | This is a simple example that uses the Event module and loads |
|
|
90 | F</etc/passwd> asynchronously: |
|
|
91 | |
|
|
92 | use Fcntl; |
|
|
93 | use Event; |
|
|
94 | use IO::AIO; |
|
|
95 | |
|
|
96 | # register the IO::AIO callback with Event |
|
|
97 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
98 | poll => 'r', |
|
|
99 | cb => \&IO::AIO::poll_cb); |
|
|
100 | |
|
|
101 | # queue the request to open /etc/passwd |
|
|
102 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
|
|
103 | my $fh = $_[0] |
|
|
104 | or die "error while opening: $!"; |
|
|
105 | |
|
|
106 | # stat'ing filehandles is generally non-blocking |
|
|
107 | my $size = -s $fh; |
|
|
108 | |
|
|
109 | # queue a request to read the file |
|
|
110 | my $contents; |
|
|
111 | aio_read $fh, 0, $size, $contents, 0, sub { |
|
|
112 | $_[0] == $size |
|
|
113 | or die "short read: $!"; |
|
|
114 | |
|
|
115 | close $fh; |
|
|
116 | |
|
|
117 | # file contents now in $contents |
|
|
118 | print $contents; |
|
|
119 | |
|
|
120 | # exit event loop and program |
|
|
121 | Event::unloop; |
|
|
122 | }; |
|
|
123 | }; |
|
|
124 | |
|
|
125 | # possibly queue up other requests, or open GUI windows, |
|
|
126 | # check for sockets etc. etc. |
|
|
127 | |
|
|
128 | # process events as long as there are some: |
|
|
129 | Event::loop; |
|
|
130 | |
87 | =head1 REQUEST ANATOMY AND LIFETIME |
131 | =head1 REQUEST ANATOMY AND LIFETIME |
88 | |
132 | |
89 | 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 |
90 | directly visible to Perl. |
134 | directly visible to Perl. |
91 | |
135 | |
… | |
… | |
142 | use strict 'vars'; |
186 | use strict 'vars'; |
143 | |
187 | |
144 | use base 'Exporter'; |
188 | use base 'Exporter'; |
145 | |
189 | |
146 | BEGIN { |
190 | BEGIN { |
147 | our $VERSION = '2.0'; |
191 | our $VERSION = '2.1'; |
148 | |
192 | |
149 | 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 |
150 | 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 |
151 | 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 |
152 | aio_copy aio_group aio_nop aio_mknod); |
196 | aio_copy aio_group aio_nop aio_mknod); |
153 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
197 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
154 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
198 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
155 | min_parallel max_parallel nreqs nready npending); |
199 | min_parallel max_parallel max_idle |
|
|
200 | nreqs nready npending nthreads |
|
|
201 | max_poll_time max_poll_reqs); |
156 | |
202 | |
157 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
203 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
158 | |
204 | |
159 | require XSLoader; |
205 | require XSLoader; |
160 | XSLoader::load ("IO::AIO", $VERSION); |
206 | XSLoader::load ("IO::AIO", $VERSION); |
… | |
… | |
347 | Asynchronously unlink (delete) a file and call the callback with the |
393 | Asynchronously unlink (delete) a file and call the callback with the |
348 | result code. |
394 | result code. |
349 | |
395 | |
350 | =item aio_mknod $path, $mode, $dev, $callback->($status) |
396 | =item aio_mknod $path, $mode, $dev, $callback->($status) |
351 | |
397 | |
|
|
398 | [EXPERIMENTAL] |
|
|
399 | |
352 | Asynchronously create a device node (or fifo). See mknod(2). |
400 | Asynchronously create a device node (or fifo). See mknod(2). |
353 | |
401 | |
354 | The only portable (POSIX) way of calling this function is: |
402 | The only (POSIX-) portable way of calling this function is: |
355 | |
403 | |
356 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
404 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
357 | |
405 | |
358 | =item aio_link $srcpath, $dstpath, $callback->($status) |
406 | =item aio_link $srcpath, $dstpath, $callback->($status) |
359 | |
407 | |
… | |
… | |
845 | |
893 | |
846 | =back |
894 | =back |
847 | |
895 | |
848 | =head2 SUPPORT FUNCTIONS |
896 | =head2 SUPPORT FUNCTIONS |
849 | |
897 | |
|
|
898 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
|
|
899 | |
850 | =over 4 |
900 | =over 4 |
851 | |
901 | |
852 | =item $fileno = IO::AIO::poll_fileno |
902 | =item $fileno = IO::AIO::poll_fileno |
853 | |
903 | |
854 | 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 |
… | |
… | |
858 | |
908 | |
859 | See C<poll_cb> for an example. |
909 | See C<poll_cb> for an example. |
860 | |
910 | |
861 | =item IO::AIO::poll_cb |
911 | =item IO::AIO::poll_cb |
862 | |
912 | |
863 | 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 |
864 | regularly. Returns the number of events processed. Returns immediately |
914 | regularly. Returns the number of events processed. Returns immediately |
865 | 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>. |
866 | |
917 | |
867 | If not all requests were processed for whatever reason, the filehandle |
918 | If not all requests were processed for whatever reason, the filehandle |
868 | will still be ready when C<poll_cb> returns. |
919 | will still be ready when C<poll_cb> returns. |
869 | |
920 | |
870 | Example: Install an Event watcher that automatically calls |
921 | Example: Install an Event watcher that automatically calls |
… | |
… | |
872 | |
923 | |
873 | Event->io (fd => IO::AIO::poll_fileno, |
924 | Event->io (fd => IO::AIO::poll_fileno, |
874 | poll => 'r', async => 1, |
925 | poll => 'r', async => 1, |
875 | cb => \&IO::AIO::poll_cb); |
926 | cb => \&IO::AIO::poll_cb); |
876 | |
927 | |
877 | =item IO::AIO::poll_some $max_requests |
928 | =item IO::AIO::max_poll_reqs $nreqs |
878 | |
929 | |
879 | Similar to C<poll_cb>, but only processes up to C<$max_requests> requests |
930 | =item IO::AIO::max_poll_time $seconds |
880 | at a time. |
|
|
881 | |
931 | |
882 | 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) |
883 | 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. |
884 | |
943 | |
885 | Example: Install an Event watcher that automatically calls |
944 | Example: Install an Event watcher that automatically calls |
886 | 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 |
887 | program get the CPU sometimes even under high AIO load. |
946 | program get the CPU sometimes even under high AIO load. |
888 | |
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 |
889 | Event->io (fd => IO::AIO::poll_fileno, |
952 | Event->io (fd => IO::AIO::poll_fileno, |
890 | poll => 'r', nice => 1, |
953 | poll => 'r', nice => 1, |
891 | cb => sub { IO::AIO::poll_some 256 }); |
954 | cb => &IO::AIO::poll_cb); |
892 | |
955 | |
893 | =item IO::AIO::poll_wait |
956 | =item IO::AIO::poll_wait |
894 | |
957 | |
895 | 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 |
896 | 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 |
897 | for some requests to finish). |
960 | wait for some requests to finish). |
898 | |
961 | |
899 | See C<nreqs> for an example. |
962 | See C<nreqs> for an example. |
900 | |
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 | |
901 | =item IO::AIO::nreqs |
973 | =item IO::AIO::flush |
902 | |
974 | |
903 | Returns the number of requests currently in the ready, execute or pending |
975 | Wait till all outstanding AIO requests have been handled. |
904 | states (i.e. for which their callback has not been invoked yet). |
|
|
905 | |
976 | |
906 | Example: wait till there are no outstanding requests anymore: |
977 | Strictly equivalent to: |
907 | |
978 | |
908 | IO::AIO::poll_wait, IO::AIO::poll_cb |
979 | IO::AIO::poll_wait, IO::AIO::poll_cb |
909 | while IO::AIO::nreqs; |
980 | while IO::AIO::nreqs; |
910 | |
981 | |
911 | =item IO::AIO::nready |
982 | =head3 CONTROLLING THE NUMBER OF THREADS |
912 | |
|
|
913 | Returns the number of requests currently in the ready state (not yet |
|
|
914 | executed). |
|
|
915 | |
|
|
916 | =item IO::AIO::npending |
|
|
917 | |
|
|
918 | Returns the number of requests currently in the pending state (executed, |
|
|
919 | but not yet processed by poll_cb). |
|
|
920 | |
|
|
921 | =item IO::AIO::flush |
|
|
922 | |
|
|
923 | Wait till all outstanding AIO requests have been handled. |
|
|
924 | |
|
|
925 | Strictly equivalent to: |
|
|
926 | |
|
|
927 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
928 | while IO::AIO::nreqs; |
|
|
929 | |
|
|
930 | =item IO::AIO::poll |
|
|
931 | |
|
|
932 | Waits until some requests have been handled. |
|
|
933 | |
|
|
934 | Strictly equivalent to: |
|
|
935 | |
|
|
936 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
937 | if IO::AIO::nreqs; |
|
|
938 | |
983 | |
939 | =item IO::AIO::min_parallel $nthreads |
984 | =item IO::AIO::min_parallel $nthreads |
940 | |
985 | |
941 | Set the minimum number of AIO threads to C<$nthreads>. The current |
986 | Set the minimum number of AIO threads to C<$nthreads>. The current |
942 | default is C<8>, which means eight asynchronous operations can execute |
987 | default is C<8>, which means eight asynchronous operations can execute |
943 | concurrently at any one time (the number of outstanding requests, |
988 | concurrently at any one time (the number of outstanding requests, |
944 | however, is unlimited). |
989 | however, is unlimited). |
945 | |
990 | |
946 | 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 |
947 | 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. |
948 | |
995 | |
949 | 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 |
950 | Linux kernel versions will scale negatively with the number of threads |
997 | Linux kernel versions will scale negatively with the number of threads |
951 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
998 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
952 | versions, 4-32 threads should be fine. |
999 | versions, 4-32 threads should be fine. |
… | |
… | |
966 | 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 |
967 | 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. |
968 | |
1015 | |
969 | Under normal circumstances you don't need to call this function. |
1016 | Under normal circumstances you don't need to call this function. |
970 | |
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 | |
971 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
1033 | =item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
972 | |
1034 | |
973 | 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 |
974 | 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 |
975 | use an C<aio_group> together with a feed callback. |
1037 | use an C<aio_group> together with a feed callback. |
… | |
… | |
983 | number of outstanding requests. |
1045 | number of outstanding requests. |
984 | |
1046 | |
985 | You can still queue as many requests as you want. Therefore, |
1047 | You can still queue as many requests as you want. Therefore, |
986 | 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 |
987 | 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). |
|
|
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). |
988 | |
1072 | |
989 | =back |
1073 | =back |
990 | |
1074 | |
991 | =cut |
1075 | =cut |
992 | |
1076 | |