… | |
… | |
28 | |
28 | |
29 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
29 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
30 | use AnyEvent::AIO; |
30 | use AnyEvent::AIO; |
31 | |
31 | |
32 | # EV integration |
32 | # EV integration |
33 | 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; |
34 | |
34 | |
35 | # Event integration |
35 | # Event integration |
36 | Event->io (fd => IO::AIO::poll_fileno, |
36 | Event->io (fd => IO::AIO::poll_fileno, |
37 | poll => 'r', |
37 | poll => 'r', |
38 | cb => \&IO::AIO::poll_cb); |
38 | cb => \&IO::AIO::poll_cb); |
… | |
… | |
49 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
49 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
50 | \&IO::AIO::poll_cb); |
50 | \&IO::AIO::poll_cb); |
51 | |
51 | |
52 | DESCRIPTION |
52 | DESCRIPTION |
53 | This module implements asynchronous I/O using whatever means your |
53 | This module implements asynchronous I/O using whatever means your |
54 | 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>). |
55 | |
56 | |
56 | Asynchronous means that operations that can normally block your program |
57 | Asynchronous means that operations that can normally block your program |
57 | (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 |
58 | 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 |
59 | extremely useful for programs that need to stay interactive even when |
60 | extremely useful for programs that need to stay interactive even when |
… | |
… | |
64 | operations concurrently. |
65 | operations concurrently. |
65 | |
66 | |
66 | 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 |
67 | sockets), using these functions on file descriptors that support |
68 | sockets), using these functions on file descriptors that support |
68 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
69 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
69 | 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 |
70 | naturally fit into such an event loop itself. |
71 | naturally fit into such an event loop itself. |
71 | |
72 | |
72 | 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 |
73 | 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 |
74 | 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 |
… | |
… | |
83 | 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 |
84 | 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 |
85 | call "poll_cb" (or other "aio_" functions) recursively. |
86 | call "poll_cb" (or other "aio_" functions) recursively. |
86 | |
87 | |
87 | EXAMPLE |
88 | EXAMPLE |
88 | 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 |
89 | /etc/passwd asynchronously: |
90 | asynchronously: |
90 | |
91 | |
91 | use Fcntl; |
92 | use Fcntl; |
92 | use Event; |
93 | use EV; |
93 | use IO::AIO; |
94 | use IO::AIO; |
94 | |
95 | |
95 | # register the IO::AIO callback with Event |
96 | # register the IO::AIO callback with EV |
96 | Event->io (fd => IO::AIO::poll_fileno, |
97 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
97 | poll => 'r', |
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98 | cb => \&IO::AIO::poll_cb); |
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99 | |
98 | |
100 | # queue the request to open /etc/passwd |
99 | # queue the request to open /etc/passwd |
101 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
100 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
102 | my $fh = shift |
101 | my $fh = shift |
103 | or die "error while opening: $!"; |
102 | or die "error while opening: $!"; |
… | |
… | |
115 | |
114 | |
116 | # file contents now in $contents |
115 | # file contents now in $contents |
117 | print $contents; |
116 | print $contents; |
118 | |
117 | |
119 | # exit event loop and program |
118 | # exit event loop and program |
120 | Event::unloop; |
119 | EV::unloop; |
121 | }; |
120 | }; |
122 | }; |
121 | }; |
123 | |
122 | |
124 | # possibly queue up other requests, or open GUI windows, |
123 | # possibly queue up other requests, or open GUI windows, |
125 | # check for sockets etc. etc. |
124 | # check for sockets etc. etc. |
126 | |
125 | |
127 | # process events as long as there are some: |
126 | # process events as long as there are some: |
128 | Event::loop; |
127 | EV::loop; |
129 | |
128 | |
130 | REQUEST ANATOMY AND LIFETIME |
129 | REQUEST ANATOMY AND LIFETIME |
131 | 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 |
132 | not directly visible to Perl. |
131 | not directly visible to Perl. |
133 | |
132 | |
… | |
… | |
442 | aio_readdir $pathname, $callback->($entries) |
441 | aio_readdir $pathname, $callback->($entries) |
443 | 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 |
444 | entire directory (i.e. opendir + readdir + closedir). The entries |
443 | entire directory (i.e. opendir + readdir + closedir). The entries |
445 | will not be sorted, and will NOT include the "." and ".." entries. |
444 | will not be sorted, and will NOT include the "." and ".." entries. |
446 | |
445 | |
447 | The callback a single argument which is either "undef" or an |
446 | The callback is passed a single argument which is either "undef" or |
448 | 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 | |
|
|
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. |
449 | |
509 | |
450 | aio_load $path, $data, $callback->($status) |
510 | aio_load $path, $data, $callback->($status) |
451 | 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 |
452 | into memory. Status is the same as with aio_read. |
512 | into memory. Status is the same as with aio_read. |
453 | |
513 | |
… | |
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500 | Implementation notes. |
560 | Implementation notes. |
501 | |
561 | |
502 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
562 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
503 | can. |
563 | can. |
504 | |
564 | |
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565 | If readdir returns file type information, then this is used directly |
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566 | to find directories. |
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567 | |
505 | After reading the directory, the modification time, size etc. of the |
568 | Otherwise, after reading the directory, the modification time, size |
506 | 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 |
507 | (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 |
508 | how many entries are directories (if >= 2). Otherwise, no knowledge |
571 | used to decide how many entries are directories (if >= 2). |
509 | of the number of subdirectories will be assumed. |
572 | Otherwise, no knowledge of the number of subdirectories will be |
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573 | assumed. |
510 | |
574 | |
511 | Then entries will be sorted into likely directories (everything |
575 | Then entries will be sorted into likely directories a non-initial |
512 | without a non-initial dot currently) and likely non-directories |
576 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
513 | (everything else). Then every entry plus an appended "/." will be |
577 | every entry plus an appended "/." will be "stat"'ed, likely |
514 | "stat"'ed, likely directories first. If that succeeds, it assumes |
578 | directories first, in order of their inode numbers. If that |
515 | 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 |
516 | be checked seperately). This is often faster than stat'ing the entry |
580 | directory (which will be checked seperately). This is often faster |
517 | itself because filesystems might detect the type of the entry |
581 | than stat'ing the entry itself because filesystems might detect the |
518 | without reading the inode data (e.g. ext2fs filetype feature). |
582 | type of the entry without reading the inode data (e.g. ext2fs |
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583 | filetype feature), even on systems that cannot return the filetype |
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584 | information on readdir. |
519 | |
585 | |
520 | If the known number of directories (link count - 2) has been |
586 | If the known number of directories (link count - 2) has been |
521 | 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. |
522 | |
588 | |
523 | This only works with certainty on POSIX (= UNIX) filesystems, which |
589 | This only works with certainty on POSIX (= UNIX) filesystems, which |
… | |
… | |
565 | operations (E.g. rename). This might not work on all operating |
631 | operations (E.g. rename). This might not work on all operating |
566 | 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 |
567 | directory changes get written to disc. It works for anything that |
633 | directory changes get written to disc. It works for anything that |
568 | can be opened for read-only, not just directories. |
634 | can be opened for read-only, not just directories. |
569 | |
635 | |
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|
636 | Future versions of this function might fall back to other methods |
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637 | when "fsync" on the directory fails (such as calling "sync"). |
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638 | |
570 | Passes 0 when everything went ok, and -1 on error. |
639 | Passes 0 when everything went ok, and -1 on error. |
571 | |
640 | |
572 | aio_group $callback->(...) |
641 | aio_group $callback->(...) |
573 | 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 |
574 | 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 |
… | |
… | |
618 | |
687 | |
619 | cancel $req |
688 | cancel $req |
620 | Cancels the request, if possible. Has the effect of skipping |
689 | Cancels the request, if possible. Has the effect of skipping |
621 | execution when entering the execute state and skipping calling the |
690 | execution when entering the execute state and skipping calling the |
622 | callback when entering the the result state, but will leave the |
691 | callback when entering the the result state, but will leave the |
623 | request otherwise untouched. That means that requests that currently |
692 | request otherwise untouched (with the exception of readdir). That |
624 | execute will not be stopped and resources held by the request will |
693 | means that requests that currently execute will not be stopped and |
625 | not be freed prematurely. |
694 | resources held by the request will not be freed prematurely. |
626 | |
695 | |
627 | cb $req $callback->(...) |
696 | cb $req $callback->(...) |
628 | Replace (or simply set) the callback registered to the request. |
697 | Replace (or simply set) the callback registered to the request. |
629 | |
698 | |
630 | IO::AIO::GRP CLASS |
699 | IO::AIO::GRP CLASS |
… | |
… | |
760 | SUPPORT FUNCTIONS |
829 | SUPPORT FUNCTIONS |
761 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
830 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
762 | $fileno = IO::AIO::poll_fileno |
831 | $fileno = IO::AIO::poll_fileno |
763 | Return the *request result pipe file descriptor*. This filehandle |
832 | Return the *request result pipe file descriptor*. This filehandle |
764 | must be polled for reading by some mechanism outside this module |
833 | must be polled for reading by some mechanism outside this module |
765 | (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 |
766 | 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 |
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|
836 | results. |
767 | |
837 | |
768 | See "poll_cb" for an example. |
838 | See "poll_cb" for an example. |
769 | |
839 | |
770 | IO::AIO::poll_cb |
840 | IO::AIO::poll_cb |
771 | 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 |
… | |
… | |
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, so normally |
849 | filehandle will still be ready when "poll_cb" returns, so normally |
780 | you don't have to do anything special to have it called later. |
850 | you don't have to do anything special to have it called later. |
781 | |
851 | |
782 | Example: Install an Event watcher that automatically calls |
852 | Example: Install an Event watcher that automatically calls |
783 | 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): |
784 | |
855 | |
785 | Event->io (fd => IO::AIO::poll_fileno, |
856 | Event->io (fd => IO::AIO::poll_fileno, |
786 | poll => 'r', async => 1, |
857 | poll => 'r', async => 1, |
787 | cb => \&IO::AIO::poll_cb); |
858 | cb => \&IO::AIO::poll_cb); |
788 | |
859 | |
… | |
… | |
928 | |
999 | |
929 | IO::AIO::npending |
1000 | IO::AIO::npending |
930 | Returns the number of requests currently in the pending state |
1001 | Returns the number of requests currently in the pending state |
931 | (executed, but not yet processed by poll_cb). |
1002 | (executed, but not yet processed by poll_cb). |
932 | |
1003 | |
|
|
1004 | MISCELLANEOUS FUNCTIONS |
|
|
1005 | IO::AIO implements some functions that might be useful, but are not |
|
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1006 | asynchronous. |
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1007 | |
|
|
1008 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1009 | Calls the "eio_sendfile_sync" function, which is like |
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1010 | "aio_sendfile", but is blocking (this makes most sense if you know |
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1011 | the input data is likely cached already and the output filehandle is |
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1012 | set to non-blocking operations). |
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1013 | |
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1014 | Returns the number of bytes copied, or -1 on error. |
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1015 | |
|
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1016 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1017 | Simply calls the "posix_fadvise" function (see it's manpage for |
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|
1018 | details). The following advice constants are avaiable: |
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|
1019 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
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1020 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
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|
1021 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
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|
1022 | |
|
|
1023 | On systems that do not implement "posix_fadvise", this function |
|
|
1024 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
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|
1025 | |
933 | FORK BEHAVIOUR |
1026 | FORK BEHAVIOUR |
934 | 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: |
935 | |
1028 | |
936 | 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 |
937 | be added in other threads and no results will be processed. After the |
1030 | be added in other threads and no results will be processed. After the |