… | |
… | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use IO::AIO; |
5 | use IO::AIO; |
6 | |
6 | |
7 | DESCRIPTION |
7 | DESCRIPTION |
8 | This module implements asynchronous I/O using whatever means your |
8 | This module implements asynchronous I/O using whatever means your |
9 | operating system supports. Currently, it falls back to Linux::AIO if |
9 | operating system supports. |
10 | that module is available, or uses pthreads to emulato aio functionality. |
|
|
11 | |
10 | |
12 | Currently, in this module a number of threads are started that execute |
11 | Currently, a number of threads are started that execute your read/writes |
13 | your read/writes and signal their completion. You don't need thread |
12 | and signal their completion. You don't need thread support in your libc |
14 | support in your libc or perl, and the threads created by this module |
13 | or perl, and the threads created by this module will not be visible to |
15 | will not be visible to the pthreads library. |
14 | the pthreads library. In the future, this module might make use of the |
|
|
15 | native aio functions available on many operating systems. However, they |
|
|
16 | are often not well-supported (Linux doesn't allow them on normal files |
|
|
17 | currently, for example), and they would only support aio_read and |
|
|
18 | aio_write, so the remaining functionality would have to be implemented |
|
|
19 | using threads anyway. |
16 | |
20 | |
17 | Although the module will work with in the presence of other threads, it |
21 | Although the module will work with in the presence of other threads, it |
18 | is not reentrant, so use appropriate locking yourself. |
22 | is currently not reentrant, so use appropriate locking yourself. |
19 | |
23 | |
20 | API NOTES |
24 | API NOTES |
21 | All the "aio_*" calls are more or less thin wrappers around the syscall |
25 | All the "aio_*" calls are more or less thin wrappers around the syscall |
22 | with the same name (sans "aio_"). The arguments are similar or |
26 | with the same name (sans "aio_"). The arguments are similar or |
23 | identical, and they all accept an additional $callback argument which |
27 | identical, and they all accept an additional $callback argument which |
… | |
… | |
90 | |
94 | |
91 | IO::AIO::poll_wait, IO::AIO::poll_cb |
95 | IO::AIO::poll_wait, IO::AIO::poll_cb |
92 | while IO::AIO::nreqs; |
96 | while IO::AIO::nreqs; |
93 | |
97 | |
94 | aio_open $pathname, $flags, $mode, $callback |
98 | aio_open $pathname, $flags, $mode, $callback |
95 | Asynchronously open or create a file and call the callback with the |
99 | Asynchronously open or create a file and call the callback with a |
96 | filedescriptor (NOT a perl filehandle, sorry for that, but watch |
100 | newly created filehandle for the file. |
97 | out, this might change in the future). |
101 | |
|
|
102 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
|
|
103 | above, for an explanation. |
98 | |
104 | |
99 | The $mode argument is a bitmask. See the "Fcntl" module for a list. |
105 | The $mode argument is a bitmask. See the "Fcntl" module for a list. |
100 | They are the same as used in "sysopen". |
106 | They are the same as used in "sysopen". |
101 | |
107 | |
102 | Example: |
108 | Example: |
103 | |
109 | |
104 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
110 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
105 | if ($_[0] >= 0) { |
111 | if ($_[0]) { |
106 | open my $fh, "<&$_[0]"; # create a copy for perl |
|
|
107 | aio_close $_[0], sub { }; # close the aio handle |
|
|
108 | print "open successful, fh is $fh\n"; |
112 | print "open successful, fh is $_[0]\n"; |
109 | ... |
113 | ... |
110 | } else { |
114 | } else { |
111 | die "open failed: $!\n"; |
115 | die "open failed: $!\n"; |
112 | } |
116 | } |
113 | }; |
117 | }; |
114 | |
118 | |
115 | aio_close $fh, $callback |
119 | aio_close $fh, $callback |
116 | Asynchronously close a file and call the callback with the result |
120 | Asynchronously close a file and call the callback with the result |
117 | code. |
121 | code. *WARNING:* although accepted, you should not pass in a perl |
|
|
122 | filehandle here, as perl will likely close the file descriptor |
|
|
123 | itself when the filehandle is destroyed. Normally, you can safely |
|
|
124 | call perls "close" or just let filehandles go out of scope. |
118 | |
125 | |
119 | aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
126 | aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
120 | aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
127 | aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
121 | Reads or writes "length" bytes from the specified "fh" and "offset" |
128 | Reads or writes "length" bytes from the specified "fh" and "offset" |
122 | into the scalar given by "data" and offset "dataoffset" and calls |
129 | into the scalar given by "data" and offset "dataoffset" and calls |
… | |
… | |
131 | print "read <$buffer>\n"; |
138 | print "read <$buffer>\n"; |
132 | }; |
139 | }; |
133 | |
140 | |
134 | aio_readahead $fh,$offset,$length, $callback |
141 | aio_readahead $fh,$offset,$length, $callback |
135 | Asynchronously reads the specified byte range into the page cache, |
142 | Asynchronously reads the specified byte range into the page cache, |
136 | using the "readahead" syscall. |
143 | using the "readahead" syscall. If that syscall doesn't exist the |
|
|
144 | status will be -1 and $! is set to ENOSYS. |
137 | |
145 | |
138 | readahead() populates the page cache with data from a file so that |
146 | readahead() populates the page cache with data from a file so that |
139 | subsequent reads from that file will not block on disk I/O. The |
147 | subsequent reads from that file will not block on disk I/O. The |
140 | $offset argument specifies the starting point from which data is to |
148 | $offset argument specifies the starting point from which data is to |
141 | be read and $length specifies the number of bytes to be read. I/O is |
149 | be read and $length specifies the number of bytes to be read. I/O is |
… | |
… | |
177 | aio_fdatasync $fh, $callback |
185 | aio_fdatasync $fh, $callback |
178 | Asynchronously call fdatasync on the given filehandle and call the |
186 | Asynchronously call fdatasync on the given filehandle and call the |
179 | callback with the fdatasync result code. |
187 | callback with the fdatasync result code. |
180 | |
188 | |
181 | BUGS |
189 | BUGS |
182 | This module has been extensively tested in a large and very busy |
190 | - could be optimized to use more semaphores instead of filehandles. |
183 | webserver for many years now. |
|
|
184 | |
|
|
185 | - aio_open gives a fd, but all other functions expect a perl filehandle. |
|
|
186 | |
191 | |
187 | SEE ALSO |
192 | SEE ALSO |
188 | Coro. |
193 | Coro, Linux::AIO. |
189 | |
194 | |
190 | AUTHOR |
195 | AUTHOR |
191 | Marc Lehmann <schmorp@schmorp.de> |
196 | Marc Lehmann <schmorp@schmorp.de> |
192 | http://home.schmorp.de/ |
197 | http://home.schmorp.de/ |
193 | |
198 | |