… | |
… | |
24 | $req->cancel; # cancel request if still in queue |
24 | $req->cancel; # cancel request if still in queue |
25 | |
25 | |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
27 | add $grp aio_stat "..." for ...; |
27 | add $grp aio_stat "..." for ...; |
28 | |
28 | |
29 | # AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...) |
29 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
30 | open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; |
30 | use AnyEvent::AIO; |
31 | my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); |
|
|
32 | |
31 | |
33 | # EV integration |
32 | # EV integration |
34 | my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
33 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
35 | |
34 | |
36 | # Event integration |
35 | # Event integration |
37 | Event->io (fd => IO::AIO::poll_fileno, |
36 | Event->io (fd => IO::AIO::poll_fileno, |
38 | poll => 'r', |
37 | poll => 'r', |
39 | cb => \&IO::AIO::poll_cb); |
38 | cb => \&IO::AIO::poll_cb); |
… | |
… | |
50 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
49 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
51 | \&IO::AIO::poll_cb); |
50 | \&IO::AIO::poll_cb); |
52 | |
51 | |
53 | DESCRIPTION |
52 | DESCRIPTION |
54 | This module implements asynchronous I/O using whatever means your |
53 | This module implements asynchronous I/O using whatever means your |
55 | operating system supports. |
54 | operating system supports. It is implemented as an interface to "libeio" |
|
|
55 | (<http://software.schmorp.de/pkg/libeio.html>). |
56 | |
56 | |
57 | Asynchronous means that operations that can normally block your program |
57 | Asynchronous means that operations that can normally block your program |
58 | (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 |
59 | 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 |
60 | extremely useful for programs that need to stay interactive even when |
60 | extremely useful for programs that need to stay interactive even when |
… | |
… | |
65 | operations concurrently. |
65 | operations concurrently. |
66 | |
66 | |
67 | 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 |
68 | sockets), using these functions on file descriptors that support |
68 | sockets), using these functions on file descriptors that support |
69 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
69 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
70 | Use an event loop for that (such as the Event module): IO::AIO will |
70 | Use an event loop for that (such as the EV module): IO::AIO will |
71 | naturally fit into such an event loop itself. |
71 | naturally fit into such an event loop itself. |
72 | |
72 | |
73 | 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 |
74 | 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 |
75 | 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 |
… | |
… | |
84 | it is currently not reentrant in any way, so use appropriate locking |
84 | it is currently not reentrant in any way, so use appropriate locking |
85 | yourself, always call "poll_cb" from within the same thread, or never |
85 | yourself, always call "poll_cb" from within the same thread, or never |
86 | call "poll_cb" (or other "aio_" functions) recursively. |
86 | call "poll_cb" (or other "aio_" functions) recursively. |
87 | |
87 | |
88 | EXAMPLE |
88 | EXAMPLE |
89 | 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 |
90 | /etc/passwd asynchronously: |
90 | asynchronously: |
91 | |
91 | |
92 | use Fcntl; |
92 | use Fcntl; |
93 | use Event; |
93 | use EV; |
94 | use IO::AIO; |
94 | use IO::AIO; |
95 | |
95 | |
96 | # register the IO::AIO callback with Event |
96 | # register the IO::AIO callback with EV |
97 | Event->io (fd => IO::AIO::poll_fileno, |
97 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
98 | poll => 'r', |
|
|
99 | cb => \&IO::AIO::poll_cb); |
|
|
100 | |
98 | |
101 | # queue the request to open /etc/passwd |
99 | # queue the request to open /etc/passwd |
102 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
100 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
103 | my $fh = shift |
101 | my $fh = shift |
104 | or die "error while opening: $!"; |
102 | or die "error while opening: $!"; |
… | |
… | |
116 | |
114 | |
117 | # file contents now in $contents |
115 | # file contents now in $contents |
118 | print $contents; |
116 | print $contents; |
119 | |
117 | |
120 | # exit event loop and program |
118 | # exit event loop and program |
121 | Event::unloop; |
119 | EV::unloop; |
122 | }; |
120 | }; |
123 | }; |
121 | }; |
124 | |
122 | |
125 | # possibly queue up other requests, or open GUI windows, |
123 | # possibly queue up other requests, or open GUI windows, |
126 | # check for sockets etc. etc. |
124 | # check for sockets etc. etc. |
127 | |
125 | |
128 | # process events as long as there are some: |
126 | # process events as long as there are some: |
129 | Event::loop; |
127 | EV::loop; |
130 | |
128 | |
131 | REQUEST ANATOMY AND LIFETIME |
129 | REQUEST ANATOMY AND LIFETIME |
132 | 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 |
133 | not directly visible to Perl. |
131 | not directly visible to Perl. |
134 | |
132 | |
… | |
… | |
176 | 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 |
177 | with the same name (sans "aio_"). The arguments are similar or |
175 | with the same name (sans "aio_"). The arguments are similar or |
178 | identical, and they all accept an additional (and optional) $callback |
176 | identical, and they all accept an additional (and optional) $callback |
179 | 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 |
180 | 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 |
181 | error, unlike perl, which usually delivers "false") as it's sole |
179 | error, unlike perl, which usually delivers "false") as its sole argument |
182 | argument when the given syscall has been executed asynchronously. |
180 | after the given syscall has been executed asynchronously. |
183 | |
181 | |
184 | All functions expecting a filehandle keep a copy of the filehandle |
182 | All functions expecting a filehandle keep a copy of the filehandle |
185 | internally until the request has finished. |
183 | internally until the request has finished. |
186 | |
184 | |
187 | 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 |
… | |
… | |
200 | the user environment, d) use Glib::filename_from_unicode on unicode |
198 | the user environment, d) use Glib::filename_from_unicode on unicode |
201 | 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 |
202 | contents. |
200 | contents. |
203 | |
201 | |
204 | 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 |
205 | handles correctly wether it is set or not. |
203 | handles correctly whether it is set or not. |
206 | |
204 | |
207 | $prev_pri = aioreq_pri [$pri] |
205 | $prev_pri = aioreq_pri [$pri] |
208 | 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 |
209 | 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. |
210 | |
208 | |
… | |
… | |
265 | Asynchronously close a file and call the callback with the result |
263 | Asynchronously close a file and call the callback with the result |
266 | code. |
264 | code. |
267 | |
265 | |
268 | Unfortunately, you can't do this to perl. Perl *insists* very |
266 | Unfortunately, you can't do this to perl. Perl *insists* very |
269 | strongly on closing the file descriptor associated with the |
267 | strongly on closing the file descriptor associated with the |
270 | filehandle itself. Here is what aio_close will try: |
268 | filehandle itself. |
271 | |
269 | |
272 | 1. dup()licate the fd |
270 | Therefore, "aio_close" will not close the filehandle - instead it |
273 | 2. asynchronously close() the duplicated fd |
271 | will use dup2 to overwrite the file descriptor with the write-end of |
274 | 3. dup()licate the fd once more |
272 | a pipe (the pipe fd will be created on demand and will be cached). |
275 | 4. let perl close() the filehandle |
|
|
276 | 5. asynchronously close the duplicated fd |
|
|
277 | |
273 | |
278 | The idea is that the first close() flushes stuff to disk that |
274 | Or in other words: the file descriptor will be closed, but it will |
279 | closing an fd will flush, so when perl closes the fd, nothing much |
275 | not be free for reuse until the perl filehandle is closed. |
280 | will need to be flushed. The second async. close() will then flush |
|
|
281 | stuff to disk that closing the last fd to the file will flush. |
|
|
282 | |
|
|
283 | Just FYI, SuSv3 has this to say on close: |
|
|
284 | |
|
|
285 | All outstanding record locks owned by the process on the file |
|
|
286 | associated with the file descriptor shall be removed. |
|
|
287 | |
|
|
288 | If fildes refers to a socket, close() shall cause the socket to be |
|
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289 | destroyed. ... close() shall block for up to the current linger |
|
|
290 | interval until all data is transmitted. |
|
|
291 | [this actually sounds like a specification bug, but who knows] |
|
|
292 | |
|
|
293 | And at least Linux additionally actually flushes stuff on every |
|
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294 | close, even when the file itself is still open. |
|
|
295 | |
|
|
296 | Sounds enourmously inefficient and complicated? Yes... please show |
|
|
297 | me how to nuke perl's fd out of existence... |
|
|
298 | |
276 | |
299 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
277 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
300 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
278 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
301 | Reads or writes $length bytes from the specified $fh and $offset |
279 | Reads or writes $length bytes from or to the specified $fh and |
302 | into the scalar given by $data and offset $dataoffset and calls the |
280 | $offset into the scalar given by $data and offset $dataoffset and |
303 | callback without the actual number of bytes read (or -1 on error, |
281 | calls the callback without the actual number of bytes read (or -1 on |
304 | just like the syscall). |
282 | error, just like the syscall). |
|
|
283 | |
|
|
284 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
|
|
285 | offset plus the actual number of bytes read. |
305 | |
286 | |
306 | If $offset is undefined, then the current file descriptor offset |
287 | If $offset is undefined, then the current file descriptor offset |
307 | will be used (and updated), otherwise the file descriptor offset |
288 | will be used (and updated), otherwise the file descriptor offset |
308 | will not be changed by these calls. |
289 | will not be changed by these calls. |
309 | |
290 | |
… | |
… | |
460 | aio_readdir $pathname, $callback->($entries) |
441 | aio_readdir $pathname, $callback->($entries) |
461 | 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 |
462 | entire directory (i.e. opendir + readdir + closedir). The entries |
443 | entire directory (i.e. opendir + readdir + closedir). The entries |
463 | will not be sorted, and will NOT include the "." and ".." entries. |
444 | will not be sorted, and will NOT include the "." and ".." entries. |
464 | |
445 | |
465 | The callback a single argument which is either "undef" or an |
446 | The callback is passed a single argument which is either "undef" or |
466 | array-ref with the filenames. |
447 | an array-ref with the filenames. |
|
|
448 | |
|
|
449 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
|
|
450 | Quite similar to "aio_readdir", but the $flags argument allows to |
|
|
451 | tune behaviour and output format. In case of an error, $entries will |
|
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452 | be "undef". |
|
|
453 | |
|
|
454 | The flags are a combination of the following constants, ORed |
|
|
455 | together (the flags will also be passed to the callback, possibly |
|
|
456 | modified): |
|
|
457 | |
|
|
458 | IO::AIO::READDIR_DENTS |
|
|
459 | When this flag is off, then the callback gets an arrayref with |
|
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460 | of names only (as with "aio_readdir"), otherwise it gets an |
|
|
461 | arrayref with "[$name, $type, $inode]" arrayrefs, each |
|
|
462 | describing a single directory entry in more detail. |
|
|
463 | |
|
|
464 | $name is the name of the entry. |
|
|
465 | |
|
|
466 | $type is one of the "IO::AIO::DT_xxx" constants: |
|
|
467 | |
|
|
468 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
|
|
469 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
|
|
470 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
|
|
471 | |
|
|
472 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
|
|
473 | you need to know, you have to run stat yourself. Also, for speed |
|
|
474 | reasons, the $type scalars are read-only: you can not modify |
|
|
475 | them. |
|
|
476 | |
|
|
477 | $inode is the inode number (which might not be exact on systems |
|
|
478 | with 64 bit inode numbers and 32 bit perls). This field has |
|
|
479 | unspecified content on systems that do not deliver the inode |
|
|
480 | information. |
|
|
481 | |
|
|
482 | IO::AIO::READDIR_DIRS_FIRST |
|
|
483 | When this flag is set, then the names will be returned in an |
|
|
484 | order where likely directories come first. This is useful when |
|
|
485 | you need to quickly find directories, or you want to find all |
|
|
486 | directories while avoiding to stat() each entry. |
|
|
487 | |
|
|
488 | If the system returns type information in readdir, then this is |
|
|
489 | used to find directories directly. Otherwise, likely directories |
|
|
490 | are files beginning with ".", or otherwise files with no dots, |
|
|
491 | of which files with short names are tried first. |
|
|
492 | |
|
|
493 | IO::AIO::READDIR_STAT_ORDER |
|
|
494 | When this flag is set, then the names will be returned in an |
|
|
495 | order suitable for stat()'ing each one. That is, when you plan |
|
|
496 | to stat() all files in the given directory, then the returned |
|
|
497 | order will likely be fastest. |
|
|
498 | |
|
|
499 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
|
|
500 | specified, then the likely dirs come first, resulting in a less |
|
|
501 | optimal stat order. |
|
|
502 | |
|
|
503 | IO::AIO::READDIR_FOUND_UNKNOWN |
|
|
504 | This flag should not be set when calling "aio_readdirx". |
|
|
505 | Instead, it is being set by "aio_readdirx", when any of the |
|
|
506 | $type's found were "IO::AIO::DT_UNKNOWN". The absense of this |
|
|
507 | flag therefore indicates that all $type's are known, which can |
|
|
508 | be used to speed up some algorithms. |
467 | |
509 | |
468 | aio_load $path, $data, $callback->($status) |
510 | aio_load $path, $data, $callback->($status) |
469 | This is a composite request that tries to fully load the given file |
511 | This is a composite request that tries to fully load the given file |
470 | into memory. Status is the same as with aio_read. |
512 | into memory. Status is the same as with aio_read. |
471 | |
513 | |
472 | aio_copy $srcpath, $dstpath, $callback->($status) |
514 | aio_copy $srcpath, $dstpath, $callback->($status) |
473 | Try to copy the *file* (directories not supported as either source |
515 | Try to copy the *file* (directories not supported as either source |
474 | or destination) from $srcpath to $dstpath and call the callback with |
516 | or destination) from $srcpath to $dstpath and call the callback with |
475 | the 0 (error) or -1 ok. |
517 | the 0 (error) or -1 ok. |
476 | |
518 | |
477 | This is a composite request that it creates the destination file |
519 | This is a composite request that creates the destination file with |
478 | 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 |
479 | using "aio_sendfile", followed by restoring atime, mtime, access |
521 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
480 | mode and uid/gid, in that order. |
522 | uid/gid, in that order. |
481 | |
523 | |
482 | If an error occurs, the partial destination file will be unlinked, |
524 | If an error occurs, the partial destination file will be unlinked, |
483 | if possible, except when setting atime, mtime, access mode and |
525 | if possible, except when setting atime, mtime, access mode and |
484 | uid/gid, where errors are being ignored. |
526 | uid/gid, where errors are being ignored. |
485 | |
527 | |
486 | aio_move $srcpath, $dstpath, $callback->($status) |
528 | aio_move $srcpath, $dstpath, $callback->($status) |
487 | Try to move the *file* (directories not supported as either source |
529 | Try to move the *file* (directories not supported as either source |
488 | or destination) from $srcpath to $dstpath and call the callback with |
530 | or destination) from $srcpath to $dstpath and call the callback with |
489 | the 0 (error) or -1 ok. |
531 | the 0 (error) or -1 ok. |
490 | |
532 | |
491 | 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; |
492 | 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" |
493 | and, if that is successful, unlinking the $srcpath. |
535 | and, if that is successful, unlinks the $srcpath. |
494 | |
536 | |
495 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
537 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
496 | Scans a directory (similar to "aio_readdir") but additionally tries |
538 | Scans a directory (similar to "aio_readdir") but additionally tries |
497 | to efficiently separate the entries of directory $path into two sets |
539 | to efficiently separate the entries of directory $path into two sets |
498 | of names, directories you can recurse into (directories), and ones |
540 | of names, directories you can recurse into (directories), and ones |
… | |
… | |
518 | Implementation notes. |
560 | Implementation notes. |
519 | |
561 | |
520 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
562 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
521 | can. |
563 | can. |
522 | |
564 | |
|
|
565 | If readdir returns file type information, then this is used directly |
|
|
566 | to find directories. |
|
|
567 | |
523 | After reading the directory, the modification time, size etc. of the |
568 | Otherwise, after reading the directory, the modification time, size |
524 | 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 |
525 | (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 |
526 | how many entries are directories (if >= 2). Otherwise, no knowledge |
571 | used to decide how many entries are directories (if >= 2). |
527 | of the number of subdirectories will be assumed. |
572 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
573 | assumed. |
528 | |
574 | |
529 | Then entries will be sorted into likely directories (everything |
575 | Then entries will be sorted into likely directories a non-initial |
530 | without a non-initial dot currently) and likely non-directories |
576 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
531 | (everything else). Then every entry plus an appended "/." will be |
577 | every entry plus an appended "/." will be "stat"'ed, likely |
532 | "stat"'ed, likely directories first. If that succeeds, it assumes |
578 | directories first, in order of their inode numbers. If that |
533 | 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 |
534 | be checked seperately). This is often faster than stat'ing the entry |
580 | directory (which will be checked seperately). This is often faster |
535 | itself because filesystems might detect the type of the entry |
581 | than stat'ing the entry itself because filesystems might detect the |
536 | 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. |
537 | |
585 | |
538 | If the known number of directories (link count - 2) has been |
586 | If the known number of directories (link count - 2) has been |
539 | 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. |
540 | |
588 | |
541 | This only works with certainty on POSIX (= UNIX) filesystems, which |
589 | This only works with certainty on POSIX (= UNIX) filesystems, which |
… | |
… | |
563 | callback with the fdatasync result code. |
611 | callback with the fdatasync result code. |
564 | |
612 | |
565 | 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 |
566 | be detected, it will be emulated by calling "fsync" instead. |
614 | be detected, it will be emulated by calling "fsync" instead. |
567 | |
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 | |
568 | aio_pathsync $path, $callback->($status) |
628 | aio_pathsync $path, $callback->($status) |
569 | This request tries to open, fsync and close the given path. This is |
629 | This request tries to open, fsync and close the given path. This is |
570 | a composite request intended tosync directories after directory |
630 | a composite request intended to sync directories after directory |
571 | operations (E.g. rename). This might not work on all operating |
631 | operations (E.g. rename). This might not work on all operating |
572 | systems or have any specific effect, but usually it makes sure that |
632 | systems or have any specific effect, but usually it makes sure that |
573 | directory changes get written to disc. It works for anything that |
633 | directory changes get written to disc. It works for anything that |
574 | can be opened for read-only, not just directories. |
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"). |
575 | |
638 | |
576 | Passes 0 when everything went ok, and -1 on error. |
639 | Passes 0 when everything went ok, and -1 on error. |
577 | |
640 | |
578 | aio_group $callback->(...) |
641 | aio_group $callback->(...) |
579 | 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 |
… | |
… | |
624 | |
687 | |
625 | cancel $req |
688 | cancel $req |
626 | Cancels the request, if possible. Has the effect of skipping |
689 | Cancels the request, if possible. Has the effect of skipping |
627 | execution when entering the execute state and skipping calling the |
690 | execution when entering the execute state and skipping calling the |
628 | callback when entering the the result state, but will leave the |
691 | callback when entering the the result state, but will leave the |
629 | request otherwise untouched. That means that requests that currently |
692 | request otherwise untouched (with the exception of readdir). That |
630 | execute will not be stopped and resources held by the request will |
693 | means that requests that currently execute will not be stopped and |
631 | not be freed prematurely. |
694 | resources held by the request will not be freed prematurely. |
632 | |
695 | |
633 | cb $req $callback->(...) |
696 | cb $req $callback->(...) |
634 | Replace (or simply set) the callback registered to the request. |
697 | Replace (or simply set) the callback registered to the request. |
635 | |
698 | |
636 | IO::AIO::GRP CLASS |
699 | IO::AIO::GRP CLASS |
… | |
… | |
679 | Their lifetime, simplified, looks like this: when they are empty, they |
742 | Their lifetime, simplified, looks like this: when they are empty, they |
680 | 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 |
681 | "done" state, they will also finish. Otherwise they will continue to |
744 | "done" state, they will also finish. Otherwise they will continue to |
682 | exist. |
745 | exist. |
683 | |
746 | |
684 | 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 |
685 | 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 |
686 | 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 |
687 | 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. |
688 | |
752 | |
689 | add $grp ... |
753 | add $grp ... |
690 | $grp->add (...) |
754 | $grp->add (...) |
691 | 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 |
692 | 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 |
… | |
… | |
735 | does not impose any limits). |
799 | does not impose any limits). |
736 | |
800 | |
737 | 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 |
738 | automatically removed from the group. |
802 | automatically removed from the group. |
739 | |
803 | |
740 | 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. |
741 | |
806 | |
742 | Example: |
807 | Example: |
743 | |
808 | |
744 | # 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: |
745 | |
810 | |
… | |
… | |
756 | 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 |
757 | whenever the group contains less than this many requests. |
822 | whenever the group contains less than this many requests. |
758 | |
823 | |
759 | Setting the limit to 0 will pause the feeding process. |
824 | Setting the limit to 0 will pause the feeding process. |
760 | |
825 | |
|
|
826 | The default value for the limit is 0, but note that setting a feeder |
|
|
827 | automatically bumps it up to 2. |
|
|
828 | |
761 | SUPPORT FUNCTIONS |
829 | SUPPORT FUNCTIONS |
762 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
830 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
763 | $fileno = IO::AIO::poll_fileno |
831 | $fileno = IO::AIO::poll_fileno |
764 | Return the *request result pipe file descriptor*. This filehandle |
832 | Return the *request result pipe file descriptor*. This filehandle |
765 | must be polled for reading by some mechanism outside this module |
833 | must be polled for reading by some mechanism outside this module |
766 | (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 |
767 | 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. |
768 | |
837 | |
769 | See "poll_cb" for an example. |
838 | See "poll_cb" for an example. |
770 | |
839 | |
771 | IO::AIO::poll_cb |
840 | IO::AIO::poll_cb |
772 | 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 |
773 | this regularly. Returns the number of events processed. Returns |
842 | this regularly. Returns 0 if all events could be processed, or -1 if |
774 | 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 |
775 | processed depends on the settings of "IO::AIO::max_poll_req" and |
845 | the settings of "IO::AIO::max_poll_req" and |
776 | "IO::AIO::max_poll_time". |
846 | "IO::AIO::max_poll_time". |
777 | |
847 | |
778 | If not all requests were processed for whatever reason, the |
848 | If not all requests were processed for whatever reason, the |
779 | 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. |
780 | |
851 | |
781 | Example: Install an Event watcher that automatically calls |
852 | Example: Install an Event watcher that automatically calls |
782 | 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): |
783 | |
855 | |
784 | Event->io (fd => IO::AIO::poll_fileno, |
856 | Event->io (fd => IO::AIO::poll_fileno, |
785 | poll => 'r', async => 1, |
857 | poll => 'r', async => 1, |
786 | cb => \&IO::AIO::poll_cb); |
858 | cb => \&IO::AIO::poll_cb); |
787 | |
859 | |
… | |
… | |
890 | |
962 | |
891 | The default is probably ok in most situations, especially if thread |
963 | The default is probably ok in most situations, especially if thread |
892 | 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 |
893 | might want to use larger values. |
965 | might want to use larger values. |
894 | |
966 | |
895 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
967 | IO::AIO::max_outstanding $maxreqs |
896 | 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 |
897 | 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 |
898 | inexact: Better use an "aio_group" together with a feed callback. |
970 | inexact: Better use an "aio_group" together with a feed callback. |
899 | |
971 | |
900 | Sets the maximum number of outstanding requests to $nreqs. If you do |
972 | Sets the maximum number of outstanding requests to $nreqs. If you do |
… | |
… | |
904 | |
976 | |
905 | 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 |
906 | the number of outstanding requests. |
978 | the number of outstanding requests. |
907 | |
979 | |
908 | You can still queue as many requests as you want. Therefore, |
980 | You can still queue as many requests as you want. Therefore, |
909 | "max_oustsanding" is mainly useful in simple scripts (with low |
981 | "max_outstanding" is mainly useful in simple scripts (with low |
910 | 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 |
911 | (with large values). |
983 | (with large values). |
912 | |
984 | |
913 | STATISTICAL INFORMATION |
985 | STATISTICAL INFORMATION |
914 | IO::AIO::nreqs |
986 | IO::AIO::nreqs |
… | |
… | |
926 | executed). |
998 | executed). |
927 | |
999 | |
928 | IO::AIO::npending |
1000 | IO::AIO::npending |
929 | Returns the number of requests currently in the pending state |
1001 | Returns the number of requests currently in the pending state |
930 | (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". |
931 | |
1025 | |
932 | FORK BEHAVIOUR |
1026 | FORK BEHAVIOUR |
933 | 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: |
934 | |
1028 | |
935 | 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 |
… | |
… | |
964 | |
1058 | |
965 | KNOWN BUGS |
1059 | KNOWN BUGS |
966 | Known bugs will be fixed in the next release. |
1060 | Known bugs will be fixed in the next release. |
967 | |
1061 | |
968 | SEE ALSO |
1062 | SEE ALSO |
969 | Coro::AIO. |
1063 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
1064 | more natural syntax. |
970 | |
1065 | |
971 | AUTHOR |
1066 | AUTHOR |
972 | Marc Lehmann <schmorp@schmorp.de> |
1067 | Marc Lehmann <schmorp@schmorp.de> |
973 | http://home.schmorp.de/ |
1068 | http://home.schmorp.de/ |
974 | |
1069 | |