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61 | faster on a RAID volume or over NFS when you do a number of stat |
61 | faster on a RAID volume or over NFS when you do a number of stat |
62 | operations concurrently. |
62 | operations concurrently. |
63 | |
63 | |
64 | While most of this works on all types of file descriptors (for example |
64 | While most of this works on all types of file descriptors (for example |
65 | sockets), using these functions on file descriptors that support |
65 | sockets), using these functions on file descriptors that support |
66 | nonblocking operation (again, sockets, pipes etc.) is very inefficient |
66 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
67 | or might not work (aio_read fails on sockets/pipes/fifos). Use an event |
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68 | loop for that (such as the Event module): IO::AIO will naturally fit |
67 | Use an event loop for that (such as the Event module): IO::AIO will |
69 | into such an event loop itself. |
68 | naturally fit into such an event loop itself. |
70 | |
69 | |
71 | In this version, a number of threads are started that execute your |
70 | In this version, a number of threads are started that execute your |
72 | requests and signal their completion. You don't need thread support in |
71 | requests and signal their completion. You don't need thread support in |
73 | perl, and the threads created by this module will not be visible to |
72 | perl, and the threads created by this module will not be visible to |
74 | perl. In the future, this module might make use of the native aio |
73 | perl. In the future, this module might make use of the native aio |
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76 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
75 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
77 | files currently, for example), and they would only support aio_read and |
76 | files currently, for example), and they would only support aio_read and |
78 | aio_write, so the remaining functionality would have to be implemented |
77 | aio_write, so the remaining functionality would have to be implemented |
79 | using threads anyway. |
78 | using threads anyway. |
80 | |
79 | |
81 | Although the module will work with in the presence of other (Perl-) |
80 | Although the module will work in the presence of other (Perl-) threads, |
82 | threads, it is currently not reentrant in any way, so use appropriate |
81 | it is currently not reentrant in any way, so use appropriate locking |
83 | locking yourself, always call "poll_cb" from within the same thread, or |
82 | yourself, always call "poll_cb" from within the same thread, or never |
84 | never call "poll_cb" (or other "aio_" functions) recursively. |
83 | call "poll_cb" (or other "aio_" functions) recursively. |
85 | |
84 | |
86 | EXAMPLE |
85 | EXAMPLE |
87 | This is a simple example that uses the Event module and loads |
86 | This is a simple example that uses the Event module and loads |
88 | /etc/passwd asynchronously: |
87 | /etc/passwd asynchronously: |
89 | |
88 | |
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242 | They are the same as used by "sysopen". |
241 | They are the same as used by "sysopen". |
243 | |
242 | |
244 | Likewise, $mode specifies the mode of the newly created file, if it |
243 | Likewise, $mode specifies the mode of the newly created file, if it |
245 | didn't exist and "O_CREAT" has been given, just like perl's |
244 | didn't exist and "O_CREAT" has been given, just like perl's |
246 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
245 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
247 | create new files, and 0666 or 0777 if you do). |
246 | create new files, and 0666 or 0777 if you do). Note that the $mode |
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247 | will be modified by the umask in effect then the request is being |
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248 | executed, so better never change the umask. |
248 | |
249 | |
249 | Example: |
250 | Example: |
250 | |
251 | |
251 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
252 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
252 | if ($_[0]) { |
253 | if ($_[0]) { |
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267 | This is supposed to be a bug in the API, so that might change. It's |
268 | This is supposed to be a bug in the API, so that might change. It's |
268 | therefore best to avoid this function. |
269 | therefore best to avoid this function. |
269 | |
270 | |
270 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
271 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
271 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
272 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
272 | Reads or writes "length" bytes from the specified "fh" and "offset" |
273 | Reads or writes $length bytes from the specified $fh and $offset |
273 | into the scalar given by "data" and offset "dataoffset" and calls |
274 | into the scalar given by $data and offset $dataoffset and calls the |
274 | the callback without the actual number of bytes read (or -1 on |
275 | callback without the actual number of bytes read (or -1 on error, |
275 | error, just like the syscall). |
276 | just like the syscall). |
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277 | |
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278 | If $offset is undefined, then the current file descriptor offset |
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279 | will be used (and updated), otherwise the file descriptor offset |
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280 | will not be changed by these calls. |
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281 | |
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282 | If $length is undefined in "aio_write", use the remaining length of |
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283 | $data. |
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284 | |
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285 | If $dataoffset is less than zero, it will be counted from the end of |
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286 | $data. |
276 | |
287 | |
277 | The $data scalar *MUST NOT* be modified in any way while the request |
288 | The $data scalar *MUST NOT* be modified in any way while the request |
278 | is outstanding. Modifying it can result in segfaults or WW3 (if the |
289 | is outstanding. Modifying it can result in segfaults or World War |
279 | necessary/optional hardware is installed). |
290 | III (if the necessary/optional hardware is installed). |
280 | |
291 | |
281 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
292 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
282 | offset 0 within the scalar: |
293 | offset 0 within the scalar: |
283 | |
294 | |
284 | aio_read $fh, 7, 15, $buffer, 0, sub { |
295 | aio_read $fh, 7, 15, $buffer, 0, sub { |
… | |
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342 | aio_stat "/etc/passwd", sub { |
353 | aio_stat "/etc/passwd", sub { |
343 | $_[0] and die "stat failed: $!"; |
354 | $_[0] and die "stat failed: $!"; |
344 | print "size is ", -s _, "\n"; |
355 | print "size is ", -s _, "\n"; |
345 | }; |
356 | }; |
346 | |
357 | |
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358 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
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359 | Works like perl's "utime" function (including the special case of |
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360 | $atime and $mtime being undef). Fractional times are supported if |
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361 | the underlying syscalls support them. |
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362 | |
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363 | When called with a pathname, uses utimes(2) if available, otherwise |
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364 | utime(2). If called on a file descriptor, uses futimes(2) if |
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365 | available, otherwise returns ENOSYS, so this is not portable. |
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366 | |
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367 | Examples: |
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368 | |
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369 | # set atime and mtime to current time (basically touch(1)): |
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370 | aio_utime "path", undef, undef; |
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371 | # set atime to current time and mtime to beginning of the epoch: |
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372 | aio_utime "path", time, undef; # undef==0 |
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373 | |
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374 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
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375 | Works like perl's "chown" function, except that "undef" for either |
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376 | $uid or $gid is being interpreted as "do not change" (but -1 can |
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377 | also be used). |
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378 | |
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379 | Examples: |
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380 | |
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381 | # same as "chown root path" in the shell: |
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382 | aio_chown "path", 0, -1; |
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383 | # same as above: |
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384 | aio_chown "path", 0, undef; |
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385 | |
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386 | aio_truncate $fh_or_path, $offset, $callback->($status) |
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387 | Works like truncate(2) or ftruncate(2). |
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388 | |
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389 | aio_chmod $fh_or_path, $mode, $callback->($status) |
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390 | Works like perl's "chmod" function. |
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391 | |
347 | aio_unlink $pathname, $callback->($status) |
392 | aio_unlink $pathname, $callback->($status) |
348 | Asynchronously unlink (delete) a file and call the callback with the |
393 | Asynchronously unlink (delete) a file and call the callback with the |
349 | result code. |
394 | result code. |
350 | |
395 | |
351 | aio_mknod $path, $mode, $dev, $callback->($status) |
396 | aio_mknod $path, $mode, $dev, $callback->($status) |
… | |
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372 | the callback. |
417 | the callback. |
373 | |
418 | |
374 | aio_rename $srcpath, $dstpath, $callback->($status) |
419 | aio_rename $srcpath, $dstpath, $callback->($status) |
375 | Asynchronously rename the object at $srcpath to $dstpath, just as |
420 | Asynchronously rename the object at $srcpath to $dstpath, just as |
376 | rename(2) and call the callback with the result code. |
421 | rename(2) and call the callback with the result code. |
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422 | |
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423 | aio_mkdir $pathname, $mode, $callback->($status) |
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424 | Asynchronously mkdir (create) a directory and call the callback with |
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425 | the result code. $mode will be modified by the umask at the time the |
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426 | request is executed, so do not change your umask. |
377 | |
427 | |
378 | aio_rmdir $pathname, $callback->($status) |
428 | aio_rmdir $pathname, $callback->($status) |
379 | Asynchronously rmdir (delete) a directory and call the callback with |
429 | Asynchronously rmdir (delete) a directory and call the callback with |
380 | the result code. |
430 | the result code. |
381 | |
431 | |
… | |
… | |
465 | |
515 | |
466 | It will also likely work on non-POSIX filesystems with reduced |
516 | It will also likely work on non-POSIX filesystems with reduced |
467 | efficiency as those tend to return 0 or 1 as link counts, which |
517 | efficiency as those tend to return 0 or 1 as link counts, which |
468 | disables the directory counting heuristic. |
518 | disables the directory counting heuristic. |
469 | |
519 | |
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520 | aio_rmtree $path, $callback->($status) |
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521 | Delete a directory tree starting (and including) $path, return the |
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522 | status of the final "rmdir" only. This is a composite request that |
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523 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
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524 | everything else. |
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525 | |
470 | aio_fsync $fh, $callback->($status) |
526 | aio_fsync $fh, $callback->($status) |
471 | Asynchronously call fsync on the given filehandle and call the |
527 | Asynchronously call fsync on the given filehandle and call the |
472 | callback with the fsync result code. |
528 | callback with the fsync result code. |
473 | |
529 | |
474 | aio_fdatasync $fh, $callback->($status) |
530 | aio_fdatasync $fh, $callback->($status) |
… | |
… | |
795 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
851 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
796 | This is a very bad function to use in interactive programs because |
852 | This is a very bad function to use in interactive programs because |
797 | it blocks, and a bad way to reduce concurrency because it is |
853 | it blocks, and a bad way to reduce concurrency because it is |
798 | inexact: Better use an "aio_group" together with a feed callback. |
854 | inexact: Better use an "aio_group" together with a feed callback. |
799 | |
855 | |
800 | Sets the maximum number of outstanding requests to $nreqs. If you to |
856 | Sets the maximum number of outstanding requests to $nreqs. If you do |
801 | queue up more than this number of requests, the next call to the |
857 | queue up more than this number of requests, the next call to the |
802 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
858 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
803 | function will block until the limit is no longer exceeded. |
859 | function will block until the limit is no longer exceeded. |
804 | |
860 | |
805 | The default value is very large, so there is no practical limit on |
861 | The default value is very large, so there is no practical limit on |
… | |
… | |
851 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
907 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
852 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
908 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
853 | scalars and other data passed into aio requests will also be locked and |
909 | scalars and other data passed into aio requests will also be locked and |
854 | will consume memory till the request has entered the done state. |
910 | will consume memory till the request has entered the done state. |
855 | |
911 | |
856 | This is now awfully much, so queuing lots of requests is not usually a |
912 | This is not awfully much, so queuing lots of requests is not usually a |
857 | problem. |
913 | problem. |
858 | |
914 | |
859 | Per-thread usage: |
915 | Per-thread usage: |
860 | |
916 | |
861 | In the execution phase, some aio requests require more memory for |
917 | In the execution phase, some aio requests require more memory for |