… | |
… | |
3 | |
3 | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use IO::AIO; |
5 | use IO::AIO; |
6 | |
6 | |
7 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
7 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
8 | my ($fh) = @_; |
8 | my $fh = shift |
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9 | or die "/etc/passwd: $!"; |
9 | ... |
10 | ... |
10 | }; |
11 | }; |
11 | |
12 | |
12 | aio_unlink "/tmp/file", sub { }; |
13 | aio_unlink "/tmp/file", sub { }; |
13 | |
14 | |
… | |
… | |
23 | $req->cancel; # cancel request if still in queue |
24 | $req->cancel; # cancel request if still in queue |
24 | |
25 | |
25 | my $grp = aio_group sub { print "all stats done\n" }; |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
26 | add $grp aio_stat "..." for ...; |
27 | add $grp aio_stat "..." for ...; |
27 | |
28 | |
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29 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
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30 | use AnyEvent::AIO; |
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31 | |
28 | # AnyEvent integration |
32 | # EV integration |
29 | open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; |
33 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
30 | my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); |
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31 | |
34 | |
32 | # Event integration |
35 | # Event integration |
33 | Event->io (fd => IO::AIO::poll_fileno, |
36 | Event->io (fd => IO::AIO::poll_fileno, |
34 | poll => 'r', |
37 | poll => 'r', |
35 | cb => \&IO::AIO::poll_cb); |
38 | cb => \&IO::AIO::poll_cb); |
… | |
… | |
46 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
49 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
47 | \&IO::AIO::poll_cb); |
50 | \&IO::AIO::poll_cb); |
48 | |
51 | |
49 | DESCRIPTION |
52 | DESCRIPTION |
50 | This module implements asynchronous I/O using whatever means your |
53 | This module implements asynchronous I/O using whatever means your |
51 | operating system supports. |
54 | operating system supports. It is implemented as an interface to "libeio" |
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55 | (<http://software.schmorp.de/pkg/libeio.html>). |
52 | |
56 | |
53 | Asynchronous means that operations that can normally block your program |
57 | Asynchronous means that operations that can normally block your program |
54 | (e.g. reading from disk) will be done asynchronously: the operation will |
58 | (e.g. reading from disk) will be done asynchronously: the operation will |
55 | still block, but you can do something else in the meantime. This is |
59 | still block, but you can do something else in the meantime. This is |
56 | extremely useful for programs that need to stay interactive even when |
60 | extremely useful for programs that need to stay interactive even when |
… | |
… | |
60 | faster on a RAID volume or over NFS when you do a number of stat |
64 | faster on a RAID volume or over NFS when you do a number of stat |
61 | operations concurrently. |
65 | operations concurrently. |
62 | |
66 | |
63 | While most of this works on all types of file descriptors (for example |
67 | While most of this works on all types of file descriptors (for example |
64 | sockets), using these functions on file descriptors that support |
68 | sockets), using these functions on file descriptors that support |
65 | nonblocking operation (again, sockets, pipes etc.) is very inefficient |
69 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
66 | or might not work (aio_read fails on sockets/pipes/fifos). Use an event |
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67 | loop for that (such as the Event module): IO::AIO will naturally fit |
70 | Use an event loop for that (such as the EV module): IO::AIO will |
68 | into such an event loop itself. |
71 | naturally fit into such an event loop itself. |
69 | |
72 | |
70 | 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 |
71 | requests and signal their completion. You don't need thread support in |
74 | requests and signal their completion. You don't need thread support in |
72 | perl, and the threads created by this module will not be visible to |
75 | perl, and the threads created by this module will not be visible to |
73 | perl. In the future, this module might make use of the native aio |
76 | perl. In the future, this module might make use of the native aio |
… | |
… | |
75 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
78 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
76 | 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 |
77 | aio_write, so the remaining functionality would have to be implemented |
80 | aio_write, so the remaining functionality would have to be implemented |
78 | using threads anyway. |
81 | using threads anyway. |
79 | |
82 | |
80 | Although the module will work with in the presence of other (Perl-) |
83 | Although the module will work in the presence of other (Perl-) threads, |
81 | threads, it is currently not reentrant in any way, so use appropriate |
84 | it is currently not reentrant in any way, so use appropriate locking |
82 | locking yourself, always call "poll_cb" from within the same thread, or |
85 | yourself, always call "poll_cb" from within the same thread, or never |
83 | never call "poll_cb" (or other "aio_" functions) recursively. |
86 | call "poll_cb" (or other "aio_" functions) recursively. |
84 | |
87 | |
85 | EXAMPLE |
88 | EXAMPLE |
86 | This is a simple example that uses the Event module and loads |
89 | This is a simple example that uses the EV module and loads /etc/passwd |
87 | /etc/passwd asynchronously: |
90 | asynchronously: |
88 | |
91 | |
89 | use Fcntl; |
92 | use Fcntl; |
90 | use Event; |
93 | use EV; |
91 | use IO::AIO; |
94 | use IO::AIO; |
92 | |
95 | |
93 | # register the IO::AIO callback with Event |
96 | # register the IO::AIO callback with EV |
94 | Event->io (fd => IO::AIO::poll_fileno, |
97 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
95 | poll => 'r', |
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96 | cb => \&IO::AIO::poll_cb); |
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97 | |
98 | |
98 | # queue the request to open /etc/passwd |
99 | # queue the request to open /etc/passwd |
99 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
100 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
100 | my $fh = $_[0] |
101 | my $fh = shift |
101 | or die "error while opening: $!"; |
102 | or die "error while opening: $!"; |
102 | |
103 | |
103 | # stat'ing filehandles is generally non-blocking |
104 | # stat'ing filehandles is generally non-blocking |
104 | my $size = -s $fh; |
105 | my $size = -s $fh; |
105 | |
106 | |
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113 | |
114 | |
114 | # file contents now in $contents |
115 | # file contents now in $contents |
115 | print $contents; |
116 | print $contents; |
116 | |
117 | |
117 | # exit event loop and program |
118 | # exit event loop and program |
118 | Event::unloop; |
119 | EV::unloop; |
119 | }; |
120 | }; |
120 | }; |
121 | }; |
121 | |
122 | |
122 | # possibly queue up other requests, or open GUI windows, |
123 | # possibly queue up other requests, or open GUI windows, |
123 | # check for sockets etc. etc. |
124 | # check for sockets etc. etc. |
124 | |
125 | |
125 | # process events as long as there are some: |
126 | # process events as long as there are some: |
126 | Event::loop; |
127 | EV::loop; |
127 | |
128 | |
128 | REQUEST ANATOMY AND LIFETIME |
129 | REQUEST ANATOMY AND LIFETIME |
129 | Every "aio_*" function creates a request. which is a C data structure |
130 | Every "aio_*" function creates a request. which is a C data structure |
130 | not directly visible to Perl. |
131 | not directly visible to Perl. |
131 | |
132 | |
… | |
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173 | All the "aio_*" calls are more or less thin wrappers around the syscall |
174 | All the "aio_*" calls are more or less thin wrappers around the syscall |
174 | with the same name (sans "aio_"). The arguments are similar or |
175 | with the same name (sans "aio_"). The arguments are similar or |
175 | identical, and they all accept an additional (and optional) $callback |
176 | identical, and they all accept an additional (and optional) $callback |
176 | argument which must be a code reference. This code reference will get |
177 | argument which must be a code reference. This code reference will get |
177 | called with the syscall return code (e.g. most syscalls return -1 on |
178 | called with the syscall return code (e.g. most syscalls return -1 on |
178 | error, unlike perl, which usually delivers "false") as it's sole |
179 | error, unlike perl, which usually delivers "false") as its sole argument |
179 | argument when the given syscall has been executed asynchronously. |
180 | after the given syscall has been executed asynchronously. |
180 | |
181 | |
181 | All functions expecting a filehandle keep a copy of the filehandle |
182 | All functions expecting a filehandle keep a copy of the filehandle |
182 | internally until the request has finished. |
183 | internally until the request has finished. |
183 | |
184 | |
184 | All functions return request objects of type IO::AIO::REQ that allow |
185 | All functions return request objects of type IO::AIO::REQ that allow |
… | |
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197 | the user environment, d) use Glib::filename_from_unicode on unicode |
198 | the user environment, d) use Glib::filename_from_unicode on unicode |
198 | filenames or e) use something else to ensure your scalar has the correct |
199 | filenames or e) use something else to ensure your scalar has the correct |
199 | contents. |
200 | contents. |
200 | |
201 | |
201 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
202 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
202 | handles correctly wether it is set or not. |
203 | handles correctly whether it is set or not. |
203 | |
204 | |
204 | $prev_pri = aioreq_pri [$pri] |
205 | $prev_pri = aioreq_pri [$pri] |
205 | Returns the priority value that would be used for the next request |
206 | Returns the priority value that would be used for the next request |
206 | and, if $pri is given, sets the priority for the next aio request. |
207 | and, if $pri is given, sets the priority for the next aio request. |
207 | |
208 | |
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241 | They are the same as used by "sysopen". |
242 | They are the same as used by "sysopen". |
242 | |
243 | |
243 | Likewise, $mode specifies the mode of the newly created file, if it |
244 | Likewise, $mode specifies the mode of the newly created file, if it |
244 | didn't exist and "O_CREAT" has been given, just like perl's |
245 | didn't exist and "O_CREAT" has been given, just like perl's |
245 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
246 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
246 | create new files, and 0666 or 0777 if you do). |
247 | create new files, and 0666 or 0777 if you do). Note that the $mode |
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248 | will be modified by the umask in effect then the request is being |
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249 | executed, so better never change the umask. |
247 | |
250 | |
248 | Example: |
251 | Example: |
249 | |
252 | |
250 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
253 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
251 | if ($_[0]) { |
254 | if ($_[0]) { |
… | |
… | |
256 | } |
259 | } |
257 | }; |
260 | }; |
258 | |
261 | |
259 | aio_close $fh, $callback->($status) |
262 | aio_close $fh, $callback->($status) |
260 | Asynchronously close a file and call the callback with the result |
263 | Asynchronously close a file and call the callback with the result |
261 | code. *WARNING:* although accepted, you should not pass in a perl |
264 | code. |
262 | filehandle here, as perl will likely close the file descriptor |
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263 | another time when the filehandle is destroyed. Normally, you can |
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264 | safely call perls "close" or just let filehandles go out of scope. |
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265 | |
265 | |
266 | This is supposed to be a bug in the API, so that might change. It's |
266 | Unfortunately, you can't do this to perl. Perl *insists* very |
267 | therefore best to avoid this function. |
267 | strongly on closing the file descriptor associated with the |
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268 | filehandle itself. |
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269 | |
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270 | Therefore, "aio_close" will not close the filehandle - instead it |
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271 | will use dup2 to overwrite the file descriptor with the write-end of |
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272 | a pipe (the pipe fd will be created on demand and will be cached). |
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273 | |
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274 | Or in other words: the file descriptor will be closed, but it will |
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275 | not be free for reuse until the perl filehandle is closed. |
268 | |
276 | |
269 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
277 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
270 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
278 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
271 | Reads or writes "length" bytes from the specified "fh" and "offset" |
279 | Reads or writes $length bytes from or to the specified $fh and |
272 | into the scalar given by "data" and offset "dataoffset" and calls |
280 | $offset into the scalar given by $data and offset $dataoffset and |
273 | the callback without the actual number of bytes read (or -1 on |
281 | calls the callback without the actual number of bytes read (or -1 on |
274 | error, just like the syscall). |
282 | error, just like the syscall). |
275 | |
283 | |
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284 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
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285 | offset plus the actual number of bytes read. |
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286 | |
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287 | If $offset is undefined, then the current file descriptor offset |
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288 | will be used (and updated), otherwise the file descriptor offset |
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289 | will not be changed by these calls. |
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290 | |
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291 | If $length is undefined in "aio_write", use the remaining length of |
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292 | $data. |
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293 | |
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294 | If $dataoffset is less than zero, it will be counted from the end of |
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295 | $data. |
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296 | |
276 | The $data scalar *MUST NOT* be modified in any way while the request |
297 | The $data scalar *MUST NOT* be modified in any way while the request |
277 | is outstanding. Modifying it can result in segfaults or WW3 (if the |
298 | is outstanding. Modifying it can result in segfaults or World War |
278 | necessary/optional hardware is installed). |
299 | III (if the necessary/optional hardware is installed). |
279 | |
300 | |
280 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
301 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
281 | offset 0 within the scalar: |
302 | offset 0 within the scalar: |
282 | |
303 | |
283 | aio_read $fh, 7, 15, $buffer, 0, sub { |
304 | aio_read $fh, 7, 15, $buffer, 0, sub { |
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341 | aio_stat "/etc/passwd", sub { |
362 | aio_stat "/etc/passwd", sub { |
342 | $_[0] and die "stat failed: $!"; |
363 | $_[0] and die "stat failed: $!"; |
343 | print "size is ", -s _, "\n"; |
364 | print "size is ", -s _, "\n"; |
344 | }; |
365 | }; |
345 | |
366 | |
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367 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
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368 | Works like perl's "utime" function (including the special case of |
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369 | $atime and $mtime being undef). Fractional times are supported if |
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370 | the underlying syscalls support them. |
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371 | |
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372 | When called with a pathname, uses utimes(2) if available, otherwise |
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373 | utime(2). If called on a file descriptor, uses futimes(2) if |
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374 | available, otherwise returns ENOSYS, so this is not portable. |
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375 | |
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376 | Examples: |
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377 | |
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378 | # set atime and mtime to current time (basically touch(1)): |
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379 | aio_utime "path", undef, undef; |
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380 | # set atime to current time and mtime to beginning of the epoch: |
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381 | aio_utime "path", time, undef; # undef==0 |
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382 | |
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383 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
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384 | Works like perl's "chown" function, except that "undef" for either |
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385 | $uid or $gid is being interpreted as "do not change" (but -1 can |
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386 | also be used). |
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387 | |
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388 | Examples: |
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389 | |
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390 | # same as "chown root path" in the shell: |
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391 | aio_chown "path", 0, -1; |
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392 | # same as above: |
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393 | aio_chown "path", 0, undef; |
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394 | |
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395 | aio_truncate $fh_or_path, $offset, $callback->($status) |
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396 | Works like truncate(2) or ftruncate(2). |
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397 | |
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398 | aio_chmod $fh_or_path, $mode, $callback->($status) |
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399 | Works like perl's "chmod" function. |
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400 | |
346 | aio_unlink $pathname, $callback->($status) |
401 | aio_unlink $pathname, $callback->($status) |
347 | Asynchronously unlink (delete) a file and call the callback with the |
402 | Asynchronously unlink (delete) a file and call the callback with the |
348 | result code. |
403 | result code. |
349 | |
404 | |
350 | aio_mknod $path, $mode, $dev, $callback->($status) |
405 | aio_mknod $path, $mode, $dev, $callback->($status) |
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372 | |
427 | |
373 | aio_rename $srcpath, $dstpath, $callback->($status) |
428 | aio_rename $srcpath, $dstpath, $callback->($status) |
374 | Asynchronously rename the object at $srcpath to $dstpath, just as |
429 | Asynchronously rename the object at $srcpath to $dstpath, just as |
375 | rename(2) and call the callback with the result code. |
430 | rename(2) and call the callback with the result code. |
376 | |
431 | |
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432 | aio_mkdir $pathname, $mode, $callback->($status) |
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433 | Asynchronously mkdir (create) a directory and call the callback with |
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434 | the result code. $mode will be modified by the umask at the time the |
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435 | request is executed, so do not change your umask. |
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436 | |
377 | aio_rmdir $pathname, $callback->($status) |
437 | aio_rmdir $pathname, $callback->($status) |
378 | Asynchronously rmdir (delete) a directory and call the callback with |
438 | Asynchronously rmdir (delete) a directory and call the callback with |
379 | the result code. |
439 | the result code. |
380 | |
440 | |
381 | aio_readdir $pathname, $callback->($entries) |
441 | aio_readdir $pathname, $callback->($entries) |
382 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
442 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
383 | entire directory (i.e. opendir + readdir + closedir). The entries |
443 | entire directory (i.e. opendir + readdir + closedir). The entries |
384 | will not be sorted, and will NOT include the "." and ".." entries. |
444 | will not be sorted, and will NOT include the "." and ".." entries. |
385 | |
445 | |
386 | The callback a single argument which is either "undef" or an |
446 | The callback is passed a single argument which is either "undef" or |
387 | array-ref with the filenames. |
447 | an array-ref with the filenames. |
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448 | |
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449 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
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450 | Quite similar to "aio_readdir", but the $flags argument allows to |
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451 | tune behaviour and output format. In case of an error, $entries will |
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452 | be "undef". |
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453 | |
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454 | The flags are a combination of the following constants, ORed |
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455 | together (the flags will also be passed to the callback, possibly |
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456 | modified): |
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457 | |
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458 | IO::AIO::READDIR_DENTS |
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459 | When this flag is off, then the callback gets an arrayref with |
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460 | of names only (as with "aio_readdir"), otherwise it gets an |
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461 | arrayref with "[$name, $type, $inode]" arrayrefs, each |
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462 | describing a single directory entry in more detail. |
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463 | |
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464 | $name is the name of the entry. |
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465 | |
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466 | $type is one of the "IO::AIO::DT_xxx" constants: |
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467 | |
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468 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
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469 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
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470 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
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471 | |
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472 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
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473 | you need to know, you have to run stat yourself. Also, for speed |
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474 | reasons, the $type scalars are read-only: you can not modify |
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475 | them. |
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476 | |
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477 | $inode is the inode number (which might not be exact on systems |
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478 | with 64 bit inode numbers and 32 bit perls). This field has |
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479 | unspecified content on systems that do not deliver the inode |
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480 | information. |
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481 | |
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482 | IO::AIO::READDIR_DIRS_FIRST |
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483 | When this flag is set, then the names will be returned in an |
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484 | order where likely directories come first. This is useful when |
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485 | you need to quickly find directories, or you want to find all |
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486 | directories while avoiding to stat() each entry. |
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487 | |
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488 | If the system returns type information in readdir, then this is |
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489 | used to find directories directly. Otherwise, likely directories |
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490 | are files beginning with ".", or otherwise files with no dots, |
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491 | of which files with short names are tried first. |
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492 | |
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493 | IO::AIO::READDIR_STAT_ORDER |
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494 | When this flag is set, then the names will be returned in an |
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495 | order suitable for stat()'ing each one. That is, when you plan |
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496 | to stat() all files in the given directory, then the returned |
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497 | order will likely be fastest. |
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498 | |
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499 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
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500 | specified, then the likely dirs come first, resulting in a less |
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501 | optimal stat order. |
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502 | |
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503 | IO::AIO::READDIR_FOUND_UNKNOWN |
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504 | This flag should not be set when calling "aio_readdirx". |
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505 | Instead, it is being set by "aio_readdirx", when any of the |
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506 | $type's found were "IO::AIO::DT_UNKNOWN". The absense of this |
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507 | flag therefore indicates that all $type's are known, which can |
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508 | be used to speed up some algorithms. |
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509 | |
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510 | aio_load $path, $data, $callback->($status) |
|
|
511 | This is a composite request that tries to fully load the given file |
|
|
512 | into memory. Status is the same as with aio_read. |
388 | |
513 | |
389 | aio_copy $srcpath, $dstpath, $callback->($status) |
514 | aio_copy $srcpath, $dstpath, $callback->($status) |
390 | Try to copy the *file* (directories not supported as either source |
515 | Try to copy the *file* (directories not supported as either source |
391 | or destination) from $srcpath to $dstpath and call the callback with |
516 | or destination) from $srcpath to $dstpath and call the callback with |
392 | the 0 (error) or -1 ok. |
517 | a status of 0 (ok) or -1 (error, see $!). |
393 | |
518 | |
394 | This is a composite request that it creates the destination file |
519 | This is a composite request that creates the destination file with |
395 | with mode 0200 and copies the contents of the source file into it |
520 | mode 0200 and copies the contents of the source file into it using |
396 | using "aio_sendfile", followed by restoring atime, mtime, access |
521 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
397 | mode and uid/gid, in that order. |
522 | uid/gid, in that order. |
398 | |
523 | |
399 | If an error occurs, the partial destination file will be unlinked, |
524 | If an error occurs, the partial destination file will be unlinked, |
400 | if possible, except when setting atime, mtime, access mode and |
525 | if possible, except when setting atime, mtime, access mode and |
401 | uid/gid, where errors are being ignored. |
526 | uid/gid, where errors are being ignored. |
402 | |
527 | |
403 | aio_move $srcpath, $dstpath, $callback->($status) |
528 | aio_move $srcpath, $dstpath, $callback->($status) |
404 | Try to move the *file* (directories not supported as either source |
529 | Try to move the *file* (directories not supported as either source |
405 | or destination) from $srcpath to $dstpath and call the callback with |
530 | or destination) from $srcpath to $dstpath and call the callback with |
406 | the 0 (error) or -1 ok. |
531 | a status of 0 (ok) or -1 (error, see $!). |
407 | |
532 | |
408 | This is a composite request that tries to rename(2) the file first. |
533 | This is a composite request that tries to rename(2) the file first; |
409 | If rename files with "EXDEV", it copies the file with "aio_copy" |
534 | if rename fails with "EXDEV", it copies the file with "aio_copy" |
410 | and, if that is successful, unlinking the $srcpath. |
535 | and, if that is successful, unlinks the $srcpath. |
411 | |
536 | |
412 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
537 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
413 | Scans a directory (similar to "aio_readdir") but additionally tries |
538 | Scans a directory (similar to "aio_readdir") but additionally tries |
414 | to efficiently separate the entries of directory $path into two sets |
539 | to efficiently separate the entries of directory $path into two sets |
415 | of names, directories you can recurse into (directories), and ones |
540 | of names, directories you can recurse into (directories), and ones |
… | |
… | |
435 | Implementation notes. |
560 | Implementation notes. |
436 | |
561 | |
437 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
562 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
438 | can. |
563 | can. |
439 | |
564 | |
|
|
565 | If readdir returns file type information, then this is used directly |
|
|
566 | to find directories. |
|
|
567 | |
440 | After reading the directory, the modification time, size etc. of the |
568 | Otherwise, after reading the directory, the modification time, size |
441 | directory before and after the readdir is checked, and if they match |
569 | etc. of the directory before and after the readdir is checked, and |
442 | (and isn't the current time), the link count will be used to decide |
570 | if they match (and isn't the current time), the link count will be |
443 | how many entries are directories (if >= 2). Otherwise, no knowledge |
571 | used to decide how many entries are directories (if >= 2). |
444 | of the number of subdirectories will be assumed. |
572 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
573 | assumed. |
445 | |
574 | |
446 | Then entries will be sorted into likely directories (everything |
575 | Then entries will be sorted into likely directories a non-initial |
447 | without a non-initial dot currently) and likely non-directories |
576 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
448 | (everything else). Then every entry plus an appended "/." will be |
577 | every entry plus an appended "/." will be "stat"'ed, likely |
449 | "stat"'ed, likely directories first. If that succeeds, it assumes |
578 | directories first, in order of their inode numbers. If that |
450 | that the entry is a directory or a symlink to directory (which will |
579 | succeeds, it assumes that the entry is a directory or a symlink to |
451 | be checked seperately). This is often faster than stat'ing the entry |
580 | directory (which will be checked seperately). This is often faster |
452 | itself because filesystems might detect the type of the entry |
581 | than stat'ing the entry itself because filesystems might detect the |
453 | without reading the inode data (e.g. ext2fs filetype feature). |
582 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
583 | filetype feature), even on systems that cannot return the filetype |
|
|
584 | information on readdir. |
454 | |
585 | |
455 | If the known number of directories (link count - 2) has been |
586 | If the known number of directories (link count - 2) has been |
456 | reached, the rest of the entries is assumed to be non-directories. |
587 | reached, the rest of the entries is assumed to be non-directories. |
457 | |
588 | |
458 | This only works with certainty on POSIX (= UNIX) filesystems, which |
589 | This only works with certainty on POSIX (= UNIX) filesystems, which |
… | |
… | |
460 | |
591 | |
461 | It will also likely work on non-POSIX filesystems with reduced |
592 | It will also likely work on non-POSIX filesystems with reduced |
462 | efficiency as those tend to return 0 or 1 as link counts, which |
593 | efficiency as those tend to return 0 or 1 as link counts, which |
463 | disables the directory counting heuristic. |
594 | disables the directory counting heuristic. |
464 | |
595 | |
|
|
596 | aio_rmtree $path, $callback->($status) |
|
|
597 | Delete a directory tree starting (and including) $path, return the |
|
|
598 | status of the final "rmdir" only. This is a composite request that |
|
|
599 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
|
|
600 | everything else. |
|
|
601 | |
|
|
602 | aio_sync $callback->($status) |
|
|
603 | Asynchronously call sync and call the callback when finished. |
|
|
604 | |
465 | aio_fsync $fh, $callback->($status) |
605 | aio_fsync $fh, $callback->($status) |
466 | Asynchronously call fsync on the given filehandle and call the |
606 | Asynchronously call fsync on the given filehandle and call the |
467 | callback with the fsync result code. |
607 | callback with the fsync result code. |
468 | |
608 | |
469 | aio_fdatasync $fh, $callback->($status) |
609 | aio_fdatasync $fh, $callback->($status) |
470 | Asynchronously call fdatasync on the given filehandle and call the |
610 | Asynchronously call fdatasync on the given filehandle and call the |
471 | callback with the fdatasync result code. |
611 | callback with the fdatasync result code. |
472 | |
612 | |
473 | If this call isn't available because your OS lacks it or it couldn't |
613 | If this call isn't available because your OS lacks it or it couldn't |
474 | be detected, it will be emulated by calling "fsync" instead. |
614 | be detected, it will be emulated by calling "fsync" instead. |
|
|
615 | |
|
|
616 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
|
|
617 | Sync the data portion of the file specified by $offset and $length |
|
|
618 | to disk (but NOT the metadata), by calling the Linux-specific |
|
|
619 | sync_file_range call. If sync_file_range is not available or it |
|
|
620 | returns ENOSYS, then fdatasync or fsync is being substituted. |
|
|
621 | |
|
|
622 | $flags can be a combination of |
|
|
623 | "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", |
|
|
624 | "IO::AIO::SYNC_FILE_RANGE_WRITE" and |
|
|
625 | "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range |
|
|
626 | manpage for details. |
|
|
627 | |
|
|
628 | aio_pathsync $path, $callback->($status) |
|
|
629 | This request tries to open, fsync and close the given path. This is |
|
|
630 | a composite request intended to sync directories after directory |
|
|
631 | operations (E.g. rename). This might not work on all operating |
|
|
632 | systems or have any specific effect, but usually it makes sure that |
|
|
633 | directory changes get written to disc. It works for anything that |
|
|
634 | can be opened for read-only, not just directories. |
|
|
635 | |
|
|
636 | Future versions of this function might fall back to other methods |
|
|
637 | when "fsync" on the directory fails (such as calling "sync"). |
|
|
638 | |
|
|
639 | Passes 0 when everything went ok, and -1 on error. |
475 | |
640 | |
476 | aio_group $callback->(...) |
641 | aio_group $callback->(...) |
477 | This is a very special aio request: Instead of doing something, it |
642 | This is a very special aio request: Instead of doing something, it |
478 | is a container for other aio requests, which is useful if you want |
643 | is a container for other aio requests, which is useful if you want |
479 | to bundle many requests into a single, composite, request with a |
644 | to bundle many requests into a single, composite, request with a |
… | |
… | |
522 | |
687 | |
523 | cancel $req |
688 | cancel $req |
524 | Cancels the request, if possible. Has the effect of skipping |
689 | Cancels the request, if possible. Has the effect of skipping |
525 | execution when entering the execute state and skipping calling the |
690 | execution when entering the execute state and skipping calling the |
526 | callback when entering the the result state, but will leave the |
691 | callback when entering the the result state, but will leave the |
527 | request otherwise untouched. That means that requests that currently |
692 | request otherwise untouched (with the exception of readdir). That |
528 | execute will not be stopped and resources held by the request will |
693 | means that requests that currently execute will not be stopped and |
529 | not be freed prematurely. |
694 | resources held by the request will not be freed prematurely. |
530 | |
695 | |
531 | cb $req $callback->(...) |
696 | cb $req $callback->(...) |
532 | Replace (or simply set) the callback registered to the request. |
697 | Replace (or simply set) the callback registered to the request. |
533 | |
698 | |
534 | IO::AIO::GRP CLASS |
699 | IO::AIO::GRP CLASS |
… | |
… | |
561 | }; |
726 | }; |
562 | |
727 | |
563 | This makes it very easy to create composite requests (see the source of |
728 | This makes it very easy to create composite requests (see the source of |
564 | "aio_move" for an application) that work and feel like simple requests. |
729 | "aio_move" for an application) that work and feel like simple requests. |
565 | |
730 | |
566 | * The IO::AIO::GRP objects will be cleaned up during calls to |
731 | * The IO::AIO::GRP objects will be cleaned up during calls to |
567 | "IO::AIO::poll_cb", just like any other request. |
732 | "IO::AIO::poll_cb", just like any other request. |
|
|
733 | |
568 | * They can be canceled like any other request. Canceling will cancel not |
734 | * They can be canceled like any other request. Canceling will cancel |
569 | only the request itself, but also all requests it contains. |
735 | not only the request itself, but also all requests it contains. |
|
|
736 | |
570 | * They can also can also be added to other IO::AIO::GRP objects. |
737 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
738 | |
571 | * You must not add requests to a group from within the group callback |
739 | * You must not add requests to a group from within the group callback |
572 | (or any later time). |
740 | (or any later time). |
573 | |
741 | |
574 | Their lifetime, simplified, looks like this: when they are empty, they |
742 | Their lifetime, simplified, looks like this: when they are empty, they |
575 | will finish very quickly. If they contain only requests that are in the |
743 | will finish very quickly. If they contain only requests that are in the |
576 | "done" state, they will also finish. Otherwise they will continue to |
744 | "done" state, they will also finish. Otherwise they will continue to |
577 | exist. |
745 | exist. |
578 | |
746 | |
579 | That means after creating a group you have some time to add requests. |
747 | That means after creating a group you have some time to add requests |
580 | And in the callbacks of those requests, you can add further requests to |
748 | (precisely before the callback has been invoked, which is only done |
581 | the group. And only when all those requests have finished will the the |
749 | within the "poll_cb"). And in the callbacks of those requests, you can |
582 | group itself finish. |
750 | add further requests to the group. And only when all those requests have |
|
|
751 | finished will the the group itself finish. |
583 | |
752 | |
584 | add $grp ... |
753 | add $grp ... |
585 | $grp->add (...) |
754 | $grp->add (...) |
586 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
755 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
587 | be added, including other groups, as long as you do not create |
756 | be added, including other groups, as long as you do not create |
… | |
… | |
594 | request itself. Useful when you queued a lot of events but got a |
763 | request itself. Useful when you queued a lot of events but got a |
595 | result early. |
764 | result early. |
596 | |
765 | |
597 | $grp->result (...) |
766 | $grp->result (...) |
598 | Set the result value(s) that will be passed to the group callback |
767 | Set the result value(s) that will be passed to the group callback |
599 | when all subrequests have finished and set thre groups errno to the |
768 | when all subrequests have finished and set the groups errno to the |
600 | current value of errno (just like calling "errno" without an error |
769 | current value of errno (just like calling "errno" without an error |
601 | number). By default, no argument will be passed and errno is zero. |
770 | number). By default, no argument will be passed and errno is zero. |
602 | |
771 | |
603 | $grp->errno ([$errno]) |
772 | $grp->errno ([$errno]) |
604 | Sets the group errno value to $errno, or the current value of errno |
773 | Sets the group errno value to $errno, or the current value of errno |
… | |
… | |
630 | does not impose any limits). |
799 | does not impose any limits). |
631 | |
800 | |
632 | If the feed does not queue more requests when called, it will be |
801 | If the feed does not queue more requests when called, it will be |
633 | automatically removed from the group. |
802 | automatically removed from the group. |
634 | |
803 | |
635 | If the feed limit is 0, it will be set to 2 automatically. |
804 | If the feed limit is 0 when this method is called, it will be set to |
|
|
805 | 2 automatically. |
636 | |
806 | |
637 | Example: |
807 | Example: |
638 | |
808 | |
639 | # stat all files in @files, but only ever use four aio requests concurrently: |
809 | # stat all files in @files, but only ever use four aio requests concurrently: |
640 | |
810 | |
… | |
… | |
651 | Sets the feeder limit for the group: The feeder will be called |
821 | Sets the feeder limit for the group: The feeder will be called |
652 | whenever the group contains less than this many requests. |
822 | whenever the group contains less than this many requests. |
653 | |
823 | |
654 | Setting the limit to 0 will pause the feeding process. |
824 | Setting the limit to 0 will pause the feeding process. |
655 | |
825 | |
|
|
826 | The default value for the limit is 0, but note that setting a feeder |
|
|
827 | automatically bumps it up to 2. |
|
|
828 | |
656 | SUPPORT FUNCTIONS |
829 | SUPPORT FUNCTIONS |
657 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
830 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
658 | $fileno = IO::AIO::poll_fileno |
831 | $fileno = IO::AIO::poll_fileno |
659 | Return the *request result pipe file descriptor*. This filehandle |
832 | Return the *request result pipe file descriptor*. This filehandle |
660 | must be polled for reading by some mechanism outside this module |
833 | must be polled for reading by some mechanism outside this module |
661 | (e.g. Event or select, see below or the SYNOPSIS). If the pipe |
834 | (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the |
662 | becomes readable you have to call "poll_cb" to check the results. |
835 | pipe becomes readable you have to call "poll_cb" to check the |
|
|
836 | results. |
663 | |
837 | |
664 | See "poll_cb" for an example. |
838 | See "poll_cb" for an example. |
665 | |
839 | |
666 | IO::AIO::poll_cb |
840 | IO::AIO::poll_cb |
667 | Process some outstanding events on the result pipe. You have to call |
841 | Process some outstanding events on the result pipe. You have to call |
668 | this regularly. Returns the number of events processed. Returns |
842 | this regularly. Returns 0 if all events could be processed, or -1 if |
669 | immediately when no events are outstanding. The amount of events |
843 | it returned earlier for whatever reason. Returns immediately when no |
|
|
844 | events are outstanding. The amount of events processed depends on |
670 | processed depends on the settings of "IO::AIO::max_poll_req" and |
845 | the settings of "IO::AIO::max_poll_req" and |
671 | "IO::AIO::max_poll_time". |
846 | "IO::AIO::max_poll_time". |
672 | |
847 | |
673 | If not all requests were processed for whatever reason, the |
848 | If not all requests were processed for whatever reason, the |
674 | filehandle will still be ready when "poll_cb" returns. |
849 | filehandle will still be ready when "poll_cb" returns, so normally |
|
|
850 | you don't have to do anything special to have it called later. |
675 | |
851 | |
676 | Example: Install an Event watcher that automatically calls |
852 | Example: Install an Event watcher that automatically calls |
677 | IO::AIO::poll_cb with high priority: |
853 | IO::AIO::poll_cb with high priority (more examples can be found in |
|
|
854 | the SYNOPSIS section, at the top of this document): |
678 | |
855 | |
679 | Event->io (fd => IO::AIO::poll_fileno, |
856 | Event->io (fd => IO::AIO::poll_fileno, |
680 | poll => 'r', async => 1, |
857 | poll => 'r', async => 1, |
681 | cb => \&IO::AIO::poll_cb); |
858 | cb => \&IO::AIO::poll_cb); |
682 | |
859 | |
… | |
… | |
711 | Event->io (fd => IO::AIO::poll_fileno, |
888 | Event->io (fd => IO::AIO::poll_fileno, |
712 | poll => 'r', nice => 1, |
889 | poll => 'r', nice => 1, |
713 | cb => &IO::AIO::poll_cb); |
890 | cb => &IO::AIO::poll_cb); |
714 | |
891 | |
715 | IO::AIO::poll_wait |
892 | IO::AIO::poll_wait |
|
|
893 | If there are any outstanding requests and none of them in the result |
716 | Wait till the result filehandle becomes ready for reading (simply |
894 | phase, wait till the result filehandle becomes ready for reading |
717 | does a "select" on the filehandle. This is useful if you want to |
895 | (simply does a "select" on the filehandle. This is useful if you |
718 | synchronously wait for some requests to finish). |
896 | want to synchronously wait for some requests to finish). |
719 | |
897 | |
720 | See "nreqs" for an example. |
898 | See "nreqs" for an example. |
721 | |
899 | |
722 | IO::AIO::poll |
900 | IO::AIO::poll |
723 | Waits until some requests have been handled. |
901 | Waits until some requests have been handled. |
724 | |
902 | |
|
|
903 | Returns the number of requests processed, but is otherwise strictly |
725 | Strictly equivalent to: |
904 | equivalent to: |
726 | |
905 | |
727 | IO::AIO::poll_wait, IO::AIO::poll_cb |
906 | IO::AIO::poll_wait, IO::AIO::poll_cb |
728 | if IO::AIO::nreqs; |
|
|
729 | |
907 | |
730 | IO::AIO::flush |
908 | IO::AIO::flush |
731 | Wait till all outstanding AIO requests have been handled. |
909 | Wait till all outstanding AIO requests have been handled. |
732 | |
910 | |
733 | Strictly equivalent to: |
911 | Strictly equivalent to: |
… | |
… | |
784 | |
962 | |
785 | The default is probably ok in most situations, especially if thread |
963 | The default is probably ok in most situations, especially if thread |
786 | creation is fast. If thread creation is very slow on your system you |
964 | creation is fast. If thread creation is very slow on your system you |
787 | might want to use larger values. |
965 | might want to use larger values. |
788 | |
966 | |
789 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
967 | IO::AIO::max_outstanding $maxreqs |
790 | This is a very bad function to use in interactive programs because |
968 | This is a very bad function to use in interactive programs because |
791 | it blocks, and a bad way to reduce concurrency because it is |
969 | it blocks, and a bad way to reduce concurrency because it is |
792 | inexact: Better use an "aio_group" together with a feed callback. |
970 | inexact: Better use an "aio_group" together with a feed callback. |
793 | |
971 | |
794 | Sets the maximum number of outstanding requests to $nreqs. If you to |
972 | Sets the maximum number of outstanding requests to $nreqs. If you do |
795 | queue up more than this number of requests, the next call to the |
973 | queue up more than this number of requests, the next call to the |
796 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
974 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
797 | function will block until the limit is no longer exceeded. |
975 | function will block until the limit is no longer exceeded. |
798 | |
976 | |
799 | The default value is very large, so there is no practical limit on |
977 | The default value is very large, so there is no practical limit on |
800 | the number of outstanding requests. |
978 | the number of outstanding requests. |
801 | |
979 | |
802 | You can still queue as many requests as you want. Therefore, |
980 | You can still queue as many requests as you want. Therefore, |
803 | "max_oustsanding" is mainly useful in simple scripts (with low |
981 | "max_outstanding" is mainly useful in simple scripts (with low |
804 | values) or as a stop gap to shield against fatal memory overflow |
982 | values) or as a stop gap to shield against fatal memory overflow |
805 | (with large values). |
983 | (with large values). |
806 | |
984 | |
807 | STATISTICAL INFORMATION |
985 | STATISTICAL INFORMATION |
808 | IO::AIO::nreqs |
986 | IO::AIO::nreqs |
… | |
… | |
820 | executed). |
998 | executed). |
821 | |
999 | |
822 | IO::AIO::npending |
1000 | IO::AIO::npending |
823 | Returns the number of requests currently in the pending state |
1001 | Returns the number of requests currently in the pending state |
824 | (executed, but not yet processed by poll_cb). |
1002 | (executed, but not yet processed by poll_cb). |
|
|
1003 | |
|
|
1004 | MISCELLANEOUS FUNCTIONS |
|
|
1005 | IO::AIO implements some functions that might be useful, but are not |
|
|
1006 | asynchronous. |
|
|
1007 | |
|
|
1008 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1009 | Calls the "eio_sendfile_sync" function, which is like |
|
|
1010 | "aio_sendfile", but is blocking (this makes most sense if you know |
|
|
1011 | the input data is likely cached already and the output filehandle is |
|
|
1012 | set to non-blocking operations). |
|
|
1013 | |
|
|
1014 | Returns the number of bytes copied, or -1 on error. |
|
|
1015 | |
|
|
1016 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1017 | Simply calls the "posix_fadvise" function (see it's manpage for |
|
|
1018 | details). The following advice constants are avaiable: |
|
|
1019 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
|
|
1020 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
|
|
1021 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
|
|
1022 | |
|
|
1023 | On systems that do not implement "posix_fadvise", this function |
|
|
1024 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
825 | |
1025 | |
826 | FORK BEHAVIOUR |
1026 | FORK BEHAVIOUR |
827 | This module should do "the right thing" when the process using it forks: |
1027 | This module should do "the right thing" when the process using it forks: |
828 | |
1028 | |
829 | Before the fork, IO::AIO enters a quiescent state where no requests can |
1029 | Before the fork, IO::AIO enters a quiescent state where no requests can |
… | |
… | |
845 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
1045 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
846 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
1046 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
847 | scalars and other data passed into aio requests will also be locked and |
1047 | scalars and other data passed into aio requests will also be locked and |
848 | will consume memory till the request has entered the done state. |
1048 | will consume memory till the request has entered the done state. |
849 | |
1049 | |
850 | This is now awfully much, so queuing lots of requests is not usually a |
1050 | This is not awfully much, so queuing lots of requests is not usually a |
851 | problem. |
1051 | problem. |
852 | |
1052 | |
853 | Per-thread usage: |
1053 | Per-thread usage: |
854 | |
1054 | |
855 | In the execution phase, some aio requests require more memory for |
1055 | In the execution phase, some aio requests require more memory for |
… | |
… | |
858 | |
1058 | |
859 | KNOWN BUGS |
1059 | KNOWN BUGS |
860 | Known bugs will be fixed in the next release. |
1060 | Known bugs will be fixed in the next release. |
861 | |
1061 | |
862 | SEE ALSO |
1062 | SEE ALSO |
863 | Coro::AIO. |
1063 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
1064 | more natural syntax. |
864 | |
1065 | |
865 | AUTHOR |
1066 | AUTHOR |
866 | Marc Lehmann <schmorp@schmorp.de> |
1067 | Marc Lehmann <schmorp@schmorp.de> |
867 | http://home.schmorp.de/ |
1068 | http://home.schmorp.de/ |
868 | |
1069 | |