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1.1 |
=head1 NAME |
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IO::AIO - Asynchronous Input/Output |
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=head1 SYNOPSIS |
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use IO::AIO; |
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1.6 |
aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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my ($fh) = @_; |
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... |
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}; |
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aio_unlink "/tmp/file", sub { }; |
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aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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1.8 |
$_[0] > 0 or die "read error: $!"; |
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1.6 |
}; |
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1.56 |
# version 2+ has request and group objects |
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use IO::AIO 2; |
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1.52 |
|
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1.68 |
aioreq_pri 4; # give next request a very high priority |
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1.52 |
my $req = aio_unlink "/tmp/file", sub { }; |
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$req->cancel; # cancel request if still in queue |
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1.56 |
my $grp = aio_group sub { print "all stats done\n" }; |
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add $grp aio_stat "..." for ...; |
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# AnyEvent integration |
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open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; |
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my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); |
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1.56 |
# Event integration |
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1.6 |
Event->io (fd => IO::AIO::poll_fileno, |
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1.7 |
poll => 'r', |
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1.6 |
cb => \&IO::AIO::poll_cb); |
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1.56 |
# Glib/Gtk2 integration |
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1.6 |
add_watch Glib::IO IO::AIO::poll_fileno, |
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1.22 |
in => sub { IO::AIO::poll_cb; 1 }; |
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1.6 |
|
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1.56 |
# Tk integration |
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1.6 |
Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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readable => \&IO::AIO::poll_cb); |
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1.56 |
# Danga::Socket integration |
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1.11 |
Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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\&IO::AIO::poll_cb); |
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1.1 |
=head1 DESCRIPTION |
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This module implements asynchronous I/O using whatever means your |
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1.2 |
operating system supports. |
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1.1 |
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1.72 |
In this version, a number of threads are started that execute your |
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requests and signal their completion. You don't need thread support |
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in perl, and the threads created by this module will not be visible |
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to perl. In the future, this module might make use of the native aio |
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functions available on many operating systems. However, they are often |
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not well-supported or restricted (Linux doesn't allow them on normal |
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files currently, for example), and they would only support aio_read and |
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aio_write, so the remaining functionality would have to be implemented |
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using threads anyway. |
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Although the module will work with in the presence of other (Perl-) |
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threads, it is currently not reentrant in any way, so use appropriate |
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locking yourself, always call C<poll_cb> from within the same thread, or |
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never call C<poll_cb> (or other C<aio_> functions) recursively. |
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=head1 REQUEST ANATOMY AND LIFETIME |
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Every C<aio_*> function creates a request. which is a C data structure not |
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directly visible to Perl. |
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If called in non-void context, every request function returns a Perl |
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object representing the request. In void context, nothing is returned, |
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which saves a bit of memory. |
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The perl object is a fairly standard ref-to-hash object. The hash contents |
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are not used by IO::AIO so you are free to store anything you like in it. |
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During their existance, aio requests travel through the following states, |
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in order: |
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=over 4 |
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=item ready |
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Immediately after a request is created it is put into the ready state, |
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waiting for a thread to execute it. |
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=item execute |
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A thread has accepted the request for processing and is currently |
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executing it (e.g. blocking in read). |
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=item pending |
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The request has been executed and is waiting for result processing. |
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While request submission and execution is fully asynchronous, result |
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processing is not and relies on the perl interpreter calling C<poll_cb> |
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(or another function with the same effect). |
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=item result |
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The request results are processed synchronously by C<poll_cb>. |
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The C<poll_cb> function will process all outstanding aio requests by |
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calling their callbacks, freeing memory associated with them and managing |
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any groups they are contained in. |
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=item done |
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Request has reached the end of its lifetime and holds no resources anymore |
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(except possibly for the Perl object, but its connection to the actual |
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aio request is severed and calling its methods will either do nothing or |
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result in a runtime error). |
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1.1 |
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=cut |
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package IO::AIO; |
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1.23 |
no warnings; |
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1.51 |
use strict 'vars'; |
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1.23 |
|
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1.1 |
use base 'Exporter'; |
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BEGIN { |
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1.55 |
our $VERSION = '2.0'; |
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1.1 |
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1.67 |
our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
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aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink |
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aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move |
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aio_group aio_nop); |
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1.70 |
our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
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1.67 |
our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
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min_parallel max_parallel max_outstanding nreqs); |
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1.1 |
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1.54 |
@IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
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1.1 |
require XSLoader; |
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1.51 |
XSLoader::load ("IO::AIO", $VERSION); |
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1.1 |
} |
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1.5 |
=head1 FUNCTIONS |
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1.1 |
|
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1.5 |
=head2 AIO FUNCTIONS |
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1.1 |
|
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1.5 |
All the C<aio_*> calls are more or less thin wrappers around the syscall |
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with the same name (sans C<aio_>). The arguments are similar or identical, |
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1.14 |
and they all accept an additional (and optional) C<$callback> argument |
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which must be a code reference. This code reference will get called with |
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the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
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perl, which usually delivers "false") as it's sole argument when the given |
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syscall has been executed asynchronously. |
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1.1 |
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1.23 |
All functions expecting a filehandle keep a copy of the filehandle |
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internally until the request has finished. |
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1.1 |
|
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1.55 |
All requests return objects of type L<IO::AIO::REQ> that allow further |
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manipulation of those requests while they are in-flight. |
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1.52 |
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1.28 |
The pathnames you pass to these routines I<must> be absolute and |
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encoded in byte form. The reason for the former is that at the time the |
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request is being executed, the current working directory could have |
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changed. Alternatively, you can make sure that you never change the |
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current working directory. |
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To encode pathnames to byte form, either make sure you either: a) |
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always pass in filenames you got from outside (command line, readdir |
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etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode |
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your pathnames to the locale (or other) encoding in effect in the user |
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environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
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use something else. |
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1.1 |
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1.5 |
=over 4 |
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1.1 |
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1.68 |
=item aioreq_pri $pri |
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Sets the priority for the next aio request. The default priority |
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is C<0>, the minimum and maximum priorities are C<-4> and C<4>, |
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respectively. Requests with higher priority will be serviced first. |
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The priority will be reset to C<0> after each call to one of the C<aio_> |
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functions. |
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1.69 |
Example: open a file with low priority, then read something from it with |
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higher priority so the read request is serviced before other low priority |
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open requests (potentially spamming the cache): |
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aioreq_pri -3; |
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aio_open ..., sub { |
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return unless $_[0]; |
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aioreq_pri -2; |
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aio_read $_[0], ..., sub { |
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... |
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}; |
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}; |
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=item aioreq_nice $pri_adjust |
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Similar to C<aioreq_pri>, but subtracts the given value from the current |
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priority, so effects are cumulative. |
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1.40 |
=item aio_open $pathname, $flags, $mode, $callback->($fh) |
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1.1 |
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1.2 |
Asynchronously open or create a file and call the callback with a newly |
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created filehandle for the file. |
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1.1 |
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The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
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for an explanation. |
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1.20 |
The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
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list. They are the same as used by C<sysopen>. |
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Likewise, C<$mode> specifies the mode of the newly created file, if it |
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didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
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except that it is mandatory (i.e. use C<0> if you don't create new files, |
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and C<0666> or C<0777> if you do). |
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1.1 |
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Example: |
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aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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1.2 |
if ($_[0]) { |
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print "open successful, fh is $_[0]\n"; |
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1.1 |
... |
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} else { |
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die "open failed: $!\n"; |
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} |
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}; |
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1.40 |
=item aio_close $fh, $callback->($status) |
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1.1 |
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1.2 |
Asynchronously close a file and call the callback with the result |
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code. I<WARNING:> although accepted, you should not pass in a perl |
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1.20 |
filehandle here, as perl will likely close the file descriptor another |
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time when the filehandle is destroyed. Normally, you can safely call perls |
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C<close> or just let filehandles go out of scope. |
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This is supposed to be a bug in the API, so that might change. It's |
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therefore best to avoid this function. |
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1.1 |
|
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1.40 |
=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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1.1 |
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1.40 |
=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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1.1 |
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Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
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into the scalar given by C<data> and offset C<dataoffset> and calls the |
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callback without the actual number of bytes read (or -1 on error, just |
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like the syscall). |
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1.31 |
The C<$data> scalar I<MUST NOT> be modified in any way while the request |
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is outstanding. Modifying it can result in segfaults or WW3 (if the |
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necessary/optional hardware is installed). |
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1.17 |
Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
260 |
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1.1 |
offset C<0> within the scalar: |
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aio_read $fh, 7, 15, $buffer, 0, sub { |
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1.9 |
$_[0] > 0 or die "read error: $!"; |
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print "read $_[0] bytes: <$buffer>\n"; |
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1.1 |
}; |
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1.50 |
=item aio_move $srcpath, $dstpath, $callback->($status) |
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1.52 |
Try to move the I<file> (directories not supported as either source or |
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destination) from C<$srcpath> to C<$dstpath> and call the callback with |
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the C<0> (error) or C<-1> ok. |
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1.50 |
|
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This is a composite request that tries to rename(2) the file first. If |
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rename files with C<EXDEV>, it creates the destination file with mode 0200 |
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and copies the contents of the source file into it using C<aio_sendfile>, |
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followed by restoring atime, mtime, access mode and uid/gid, in that |
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order, and unlinking the C<$srcpath>. |
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If an error occurs, the partial destination file will be unlinked, if |
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possible, except when setting atime, mtime, access mode and uid/gid, where |
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errors are being ignored. |
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=cut |
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sub aio_move($$$) { |
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my ($src, $dst, $cb) = @_; |
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1.58 |
my $grp = aio_group $cb; |
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1.55 |
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add $grp aio_rename $src, $dst, sub { |
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1.51 |
if ($_[0] && $! == EXDEV) { |
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1.55 |
add $grp aio_open $src, O_RDONLY, 0, sub { |
293 |
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1.50 |
if (my $src_fh = $_[0]) { |
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my @stat = stat $src_fh; |
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1.55 |
add $grp aio_open $dst, O_WRONLY, 0200, sub { |
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1.50 |
if (my $dst_fh = $_[0]) { |
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1.55 |
add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
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1.50 |
close $src_fh; |
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if ($_[0] == $stat[7]) { |
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utime $stat[8], $stat[9], $dst; |
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chmod $stat[2] & 07777, $dst_fh; |
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chown $stat[4], $stat[5], $dst_fh; |
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close $dst_fh; |
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1.55 |
add $grp aio_unlink $src, sub { |
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1.58 |
$grp->result ($_[0]); |
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1.50 |
}; |
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} else { |
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my $errno = $!; |
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1.55 |
add $grp aio_unlink $dst, sub { |
313 |
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1.50 |
$! = $errno; |
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1.58 |
$grp->result (-1); |
315 |
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1.50 |
}; |
316 |
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} |
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}; |
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} else { |
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1.58 |
$grp->result (-1); |
320 |
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1.50 |
} |
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}, |
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} else { |
324 |
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1.58 |
$grp->result (-1); |
325 |
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1.50 |
} |
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}; |
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} else { |
328 |
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1.58 |
$grp->result ($_[0]); |
329 |
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1.50 |
} |
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}; |
331 |
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1.55 |
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$grp |
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1.50 |
} |
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|
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1.40 |
=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
336 |
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1.35 |
|
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Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
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reading at byte offset C<$in_offset>, and starts writing at the current |
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file offset of C<$out_fh>. Because of that, it is not safe to issue more |
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than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each |
341 |
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other. |
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This call tries to make use of a native C<sendfile> syscall to provide |
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zero-copy operation. For this to work, C<$out_fh> should refer to a |
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socket, and C<$in_fh> should refer to mmap'able file. |
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If the native sendfile call fails or is not implemented, it will be |
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1.36 |
emulated, so you can call C<aio_sendfile> on any type of filehandle |
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regardless of the limitations of the operating system. |
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1.35 |
|
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Please note, however, that C<aio_sendfile> can read more bytes from |
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C<$in_fh> than are written, and there is no way to find out how many |
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root |
1.36 |
bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only |
354 |
|
|
provides the number of bytes written to C<$out_fh>. Only if the result |
355 |
|
|
value equals C<$length> one can assume that C<$length> bytes have been |
356 |
|
|
read. |
357 |
root |
1.35 |
|
358 |
root |
1.40 |
=item aio_readahead $fh,$offset,$length, $callback->($retval) |
359 |
root |
1.1 |
|
360 |
root |
1.20 |
C<aio_readahead> populates the page cache with data from a file so that |
361 |
root |
1.1 |
subsequent reads from that file will not block on disk I/O. The C<$offset> |
362 |
|
|
argument specifies the starting point from which data is to be read and |
363 |
|
|
C<$length> specifies the number of bytes to be read. I/O is performed in |
364 |
|
|
whole pages, so that offset is effectively rounded down to a page boundary |
365 |
|
|
and bytes are read up to the next page boundary greater than or equal to |
366 |
root |
1.20 |
(off-set+length). C<aio_readahead> does not read beyond the end of the |
367 |
root |
1.1 |
file. The current file offset of the file is left unchanged. |
368 |
|
|
|
369 |
root |
1.26 |
If that syscall doesn't exist (likely if your OS isn't Linux) it will be |
370 |
|
|
emulated by simply reading the data, which would have a similar effect. |
371 |
|
|
|
372 |
root |
1.40 |
=item aio_stat $fh_or_path, $callback->($status) |
373 |
root |
1.1 |
|
374 |
root |
1.40 |
=item aio_lstat $fh, $callback->($status) |
375 |
root |
1.1 |
|
376 |
|
|
Works like perl's C<stat> or C<lstat> in void context. The callback will |
377 |
|
|
be called after the stat and the results will be available using C<stat _> |
378 |
|
|
or C<-s _> etc... |
379 |
|
|
|
380 |
|
|
The pathname passed to C<aio_stat> must be absolute. See API NOTES, above, |
381 |
|
|
for an explanation. |
382 |
|
|
|
383 |
|
|
Currently, the stats are always 64-bit-stats, i.e. instead of returning an |
384 |
|
|
error when stat'ing a large file, the results will be silently truncated |
385 |
|
|
unless perl itself is compiled with large file support. |
386 |
|
|
|
387 |
|
|
Example: Print the length of F</etc/passwd>: |
388 |
|
|
|
389 |
|
|
aio_stat "/etc/passwd", sub { |
390 |
|
|
$_[0] and die "stat failed: $!"; |
391 |
|
|
print "size is ", -s _, "\n"; |
392 |
|
|
}; |
393 |
|
|
|
394 |
root |
1.40 |
=item aio_unlink $pathname, $callback->($status) |
395 |
root |
1.1 |
|
396 |
|
|
Asynchronously unlink (delete) a file and call the callback with the |
397 |
|
|
result code. |
398 |
|
|
|
399 |
root |
1.50 |
=item aio_link $srcpath, $dstpath, $callback->($status) |
400 |
|
|
|
401 |
|
|
Asynchronously create a new link to the existing object at C<$srcpath> at |
402 |
|
|
the path C<$dstpath> and call the callback with the result code. |
403 |
|
|
|
404 |
|
|
=item aio_symlink $srcpath, $dstpath, $callback->($status) |
405 |
|
|
|
406 |
|
|
Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
407 |
|
|
the path C<$dstpath> and call the callback with the result code. |
408 |
|
|
|
409 |
|
|
=item aio_rename $srcpath, $dstpath, $callback->($status) |
410 |
|
|
|
411 |
|
|
Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
412 |
|
|
rename(2) and call the callback with the result code. |
413 |
|
|
|
414 |
root |
1.40 |
=item aio_rmdir $pathname, $callback->($status) |
415 |
root |
1.27 |
|
416 |
|
|
Asynchronously rmdir (delete) a directory and call the callback with the |
417 |
|
|
result code. |
418 |
|
|
|
419 |
root |
1.46 |
=item aio_readdir $pathname, $callback->($entries) |
420 |
root |
1.37 |
|
421 |
|
|
Unlike the POSIX call of the same name, C<aio_readdir> reads an entire |
422 |
|
|
directory (i.e. opendir + readdir + closedir). The entries will not be |
423 |
|
|
sorted, and will B<NOT> include the C<.> and C<..> entries. |
424 |
|
|
|
425 |
|
|
The callback a single argument which is either C<undef> or an array-ref |
426 |
|
|
with the filenames. |
427 |
|
|
|
428 |
root |
1.40 |
=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
429 |
|
|
|
430 |
root |
1.52 |
Scans a directory (similar to C<aio_readdir>) but additionally tries to |
431 |
|
|
separate the entries of directory C<$path> into two sets of names, ones |
432 |
|
|
you can recurse into (directories or links to them), and ones you cannot |
433 |
|
|
recurse into (everything else). |
434 |
|
|
|
435 |
root |
1.61 |
C<aio_scandir> is a composite request that creates of many sub requests_ |
436 |
|
|
C<$maxreq> specifies the maximum number of outstanding aio requests that |
437 |
|
|
this function generates. If it is C<< <= 0 >>, then a suitable default |
438 |
|
|
will be chosen (currently 6). |
439 |
root |
1.40 |
|
440 |
|
|
On error, the callback is called without arguments, otherwise it receives |
441 |
|
|
two array-refs with path-relative entry names. |
442 |
|
|
|
443 |
|
|
Example: |
444 |
|
|
|
445 |
|
|
aio_scandir $dir, 0, sub { |
446 |
|
|
my ($dirs, $nondirs) = @_; |
447 |
|
|
print "real directories: @$dirs\n"; |
448 |
|
|
print "everything else: @$nondirs\n"; |
449 |
|
|
}; |
450 |
|
|
|
451 |
|
|
Implementation notes. |
452 |
|
|
|
453 |
|
|
The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. |
454 |
|
|
|
455 |
|
|
After reading the directory, the modification time, size etc. of the |
456 |
root |
1.52 |
directory before and after the readdir is checked, and if they match (and |
457 |
|
|
isn't the current time), the link count will be used to decide how many |
458 |
|
|
entries are directories (if >= 2). Otherwise, no knowledge of the number |
459 |
|
|
of subdirectories will be assumed. |
460 |
|
|
|
461 |
|
|
Then entries will be sorted into likely directories (everything without |
462 |
|
|
a non-initial dot currently) and likely non-directories (everything |
463 |
|
|
else). Then every entry plus an appended C</.> will be C<stat>'ed, |
464 |
|
|
likely directories first. If that succeeds, it assumes that the entry |
465 |
|
|
is a directory or a symlink to directory (which will be checked |
466 |
|
|
seperately). This is often faster than stat'ing the entry itself because |
467 |
|
|
filesystems might detect the type of the entry without reading the inode |
468 |
|
|
data (e.g. ext2fs filetype feature). |
469 |
|
|
|
470 |
|
|
If the known number of directories (link count - 2) has been reached, the |
471 |
|
|
rest of the entries is assumed to be non-directories. |
472 |
|
|
|
473 |
|
|
This only works with certainty on POSIX (= UNIX) filesystems, which |
474 |
|
|
fortunately are the vast majority of filesystems around. |
475 |
|
|
|
476 |
|
|
It will also likely work on non-POSIX filesystems with reduced efficiency |
477 |
|
|
as those tend to return 0 or 1 as link counts, which disables the |
478 |
|
|
directory counting heuristic. |
479 |
root |
1.40 |
|
480 |
|
|
=cut |
481 |
|
|
|
482 |
|
|
sub aio_scandir($$$) { |
483 |
|
|
my ($path, $maxreq, $cb) = @_; |
484 |
|
|
|
485 |
root |
1.58 |
my $grp = aio_group $cb; |
486 |
root |
1.55 |
|
487 |
root |
1.61 |
$maxreq = 6 if $maxreq <= 0; |
488 |
root |
1.40 |
|
489 |
|
|
# stat once |
490 |
root |
1.55 |
add $grp aio_stat $path, sub { |
491 |
root |
1.58 |
return $grp->result () if $_[0]; |
492 |
root |
1.52 |
my $now = time; |
493 |
root |
1.40 |
my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
494 |
|
|
|
495 |
|
|
# read the directory entries |
496 |
root |
1.55 |
add $grp aio_readdir $path, sub { |
497 |
root |
1.40 |
my $entries = shift |
498 |
root |
1.58 |
or return $grp->result (); |
499 |
root |
1.40 |
|
500 |
|
|
# stat the dir another time |
501 |
root |
1.55 |
add $grp aio_stat $path, sub { |
502 |
root |
1.40 |
my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
503 |
|
|
|
504 |
|
|
my $ndirs; |
505 |
|
|
|
506 |
|
|
# take the slow route if anything looks fishy |
507 |
root |
1.52 |
if ($hash1 ne $hash2 or (stat _)[9] == $now) { |
508 |
root |
1.40 |
$ndirs = -1; |
509 |
|
|
} else { |
510 |
|
|
# if nlink == 2, we are finished |
511 |
|
|
# on non-posix-fs's, we rely on nlink < 2 |
512 |
|
|
$ndirs = (stat _)[3] - 2 |
513 |
root |
1.58 |
or return $grp->result ([], $entries); |
514 |
root |
1.40 |
} |
515 |
|
|
|
516 |
|
|
# sort into likely dirs and likely nondirs |
517 |
|
|
# dirs == files without ".", short entries first |
518 |
|
|
$entries = [map $_->[0], |
519 |
|
|
sort { $b->[1] cmp $a->[1] } |
520 |
|
|
map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], |
521 |
|
|
@$entries]; |
522 |
|
|
|
523 |
|
|
my (@dirs, @nondirs); |
524 |
|
|
|
525 |
root |
1.74 |
my $statgrp = add $grp aio_group sub { |
526 |
|
|
$grp->result (\@dirs, \@nondirs); |
527 |
root |
1.40 |
}; |
528 |
|
|
|
529 |
root |
1.74 |
limit $statgrp $maxreq; |
530 |
|
|
feed $statgrp sub { |
531 |
|
|
return unless @$entries; |
532 |
|
|
my $entry = pop @$entries; |
533 |
|
|
|
534 |
|
|
add $statgrp aio_stat "$path/$entry/.", sub { |
535 |
|
|
if ($_[0] < 0) { |
536 |
|
|
push @nondirs, $entry; |
537 |
|
|
} else { |
538 |
|
|
# need to check for real directory |
539 |
|
|
add $statgrp aio_lstat "$path/$entry", sub { |
540 |
|
|
if (-d _) { |
541 |
|
|
push @dirs, $entry; |
542 |
|
|
|
543 |
|
|
if (!--$ndirs) { |
544 |
|
|
push @nondirs, @$entries; |
545 |
|
|
$statgrp->cancel_subs; |
546 |
|
|
} |
547 |
|
|
} else { |
548 |
|
|
push @nondirs, $entry; |
549 |
root |
1.40 |
} |
550 |
|
|
} |
551 |
|
|
} |
552 |
root |
1.74 |
}; |
553 |
root |
1.40 |
}; |
554 |
|
|
}; |
555 |
|
|
}; |
556 |
|
|
}; |
557 |
root |
1.55 |
|
558 |
|
|
$grp |
559 |
root |
1.40 |
} |
560 |
|
|
|
561 |
|
|
=item aio_fsync $fh, $callback->($status) |
562 |
root |
1.1 |
|
563 |
|
|
Asynchronously call fsync on the given filehandle and call the callback |
564 |
|
|
with the fsync result code. |
565 |
|
|
|
566 |
root |
1.40 |
=item aio_fdatasync $fh, $callback->($status) |
567 |
root |
1.1 |
|
568 |
|
|
Asynchronously call fdatasync on the given filehandle and call the |
569 |
root |
1.26 |
callback with the fdatasync result code. |
570 |
|
|
|
571 |
|
|
If this call isn't available because your OS lacks it or it couldn't be |
572 |
|
|
detected, it will be emulated by calling C<fsync> instead. |
573 |
root |
1.1 |
|
574 |
root |
1.58 |
=item aio_group $callback->(...) |
575 |
root |
1.54 |
|
576 |
root |
1.55 |
This is a very special aio request: Instead of doing something, it is a |
577 |
|
|
container for other aio requests, which is useful if you want to bundle |
578 |
root |
1.71 |
many requests into a single, composite, request with a definite callback |
579 |
|
|
and the ability to cancel the whole request with its subrequests. |
580 |
root |
1.55 |
|
581 |
|
|
Returns an object of class L<IO::AIO::GRP>. See its documentation below |
582 |
|
|
for more info. |
583 |
|
|
|
584 |
|
|
Example: |
585 |
|
|
|
586 |
|
|
my $grp = aio_group sub { |
587 |
|
|
print "all stats done\n"; |
588 |
|
|
}; |
589 |
|
|
|
590 |
|
|
add $grp |
591 |
|
|
(aio_stat ...), |
592 |
|
|
(aio_stat ...), |
593 |
|
|
...; |
594 |
|
|
|
595 |
root |
1.63 |
=item aio_nop $callback->() |
596 |
|
|
|
597 |
|
|
This is a special request - it does nothing in itself and is only used for |
598 |
|
|
side effects, such as when you want to add a dummy request to a group so |
599 |
|
|
that finishing the requests in the group depends on executing the given |
600 |
|
|
code. |
601 |
|
|
|
602 |
root |
1.64 |
While this request does nothing, it still goes through the execution |
603 |
|
|
phase and still requires a worker thread. Thus, the callback will not |
604 |
|
|
be executed immediately but only after other requests in the queue have |
605 |
|
|
entered their execution phase. This can be used to measure request |
606 |
|
|
latency. |
607 |
|
|
|
608 |
root |
1.71 |
=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
609 |
root |
1.54 |
|
610 |
|
|
Mainly used for debugging and benchmarking, this aio request puts one of |
611 |
|
|
the request workers to sleep for the given time. |
612 |
|
|
|
613 |
root |
1.56 |
While it is theoretically handy to have simple I/O scheduling requests |
614 |
root |
1.71 |
like sleep and file handle readable/writable, the overhead this creates is |
615 |
|
|
immense (it blocks a thread for a long time) so do not use this function |
616 |
|
|
except to put your application under artificial I/O pressure. |
617 |
root |
1.56 |
|
618 |
root |
1.5 |
=back |
619 |
|
|
|
620 |
root |
1.53 |
=head2 IO::AIO::REQ CLASS |
621 |
root |
1.52 |
|
622 |
|
|
All non-aggregate C<aio_*> functions return an object of this class when |
623 |
|
|
called in non-void context. |
624 |
|
|
|
625 |
|
|
=over 4 |
626 |
|
|
|
627 |
root |
1.65 |
=item cancel $req |
628 |
root |
1.52 |
|
629 |
|
|
Cancels the request, if possible. Has the effect of skipping execution |
630 |
|
|
when entering the B<execute> state and skipping calling the callback when |
631 |
|
|
entering the the B<result> state, but will leave the request otherwise |
632 |
|
|
untouched. That means that requests that currently execute will not be |
633 |
|
|
stopped and resources held by the request will not be freed prematurely. |
634 |
|
|
|
635 |
root |
1.65 |
=item cb $req $callback->(...) |
636 |
|
|
|
637 |
|
|
Replace (or simply set) the callback registered to the request. |
638 |
|
|
|
639 |
root |
1.52 |
=back |
640 |
|
|
|
641 |
root |
1.55 |
=head2 IO::AIO::GRP CLASS |
642 |
|
|
|
643 |
|
|
This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
644 |
|
|
objects of this class, too. |
645 |
|
|
|
646 |
|
|
A IO::AIO::GRP object is a special request that can contain multiple other |
647 |
|
|
aio requests. |
648 |
|
|
|
649 |
|
|
You create one by calling the C<aio_group> constructing function with a |
650 |
|
|
callback that will be called when all contained requests have entered the |
651 |
|
|
C<done> state: |
652 |
|
|
|
653 |
|
|
my $grp = aio_group sub { |
654 |
|
|
print "all requests are done\n"; |
655 |
|
|
}; |
656 |
|
|
|
657 |
|
|
You add requests by calling the C<add> method with one or more |
658 |
|
|
C<IO::AIO::REQ> objects: |
659 |
|
|
|
660 |
|
|
$grp->add (aio_unlink "..."); |
661 |
|
|
|
662 |
root |
1.58 |
add $grp aio_stat "...", sub { |
663 |
|
|
$_[0] or return $grp->result ("error"); |
664 |
|
|
|
665 |
|
|
# add another request dynamically, if first succeeded |
666 |
|
|
add $grp aio_open "...", sub { |
667 |
|
|
$grp->result ("ok"); |
668 |
|
|
}; |
669 |
|
|
}; |
670 |
root |
1.55 |
|
671 |
|
|
This makes it very easy to create composite requests (see the source of |
672 |
|
|
C<aio_move> for an application) that work and feel like simple requests. |
673 |
|
|
|
674 |
root |
1.62 |
=over 4 |
675 |
|
|
|
676 |
|
|
=item * The IO::AIO::GRP objects will be cleaned up during calls to |
677 |
root |
1.55 |
C<IO::AIO::poll_cb>, just like any other request. |
678 |
|
|
|
679 |
root |
1.62 |
=item * They can be canceled like any other request. Canceling will cancel not |
680 |
root |
1.59 |
only the request itself, but also all requests it contains. |
681 |
root |
1.55 |
|
682 |
root |
1.62 |
=item * They can also can also be added to other IO::AIO::GRP objects. |
683 |
root |
1.55 |
|
684 |
root |
1.62 |
=item * You must not add requests to a group from within the group callback (or |
685 |
root |
1.60 |
any later time). |
686 |
|
|
|
687 |
root |
1.62 |
=item * This does not harmonise well with C<max_outstanding>, so best do |
688 |
|
|
not combine C<aio_group> with it. Groups and feeders are recommended for |
689 |
|
|
this kind of concurrency-limiting. |
690 |
|
|
|
691 |
|
|
=back |
692 |
|
|
|
693 |
root |
1.55 |
Their lifetime, simplified, looks like this: when they are empty, they |
694 |
|
|
will finish very quickly. If they contain only requests that are in the |
695 |
|
|
C<done> state, they will also finish. Otherwise they will continue to |
696 |
|
|
exist. |
697 |
|
|
|
698 |
root |
1.57 |
That means after creating a group you have some time to add requests. And |
699 |
|
|
in the callbacks of those requests, you can add further requests to the |
700 |
|
|
group. And only when all those requests have finished will the the group |
701 |
|
|
itself finish. |
702 |
|
|
|
703 |
root |
1.55 |
=over 4 |
704 |
|
|
|
705 |
root |
1.65 |
=item add $grp ... |
706 |
|
|
|
707 |
root |
1.55 |
=item $grp->add (...) |
708 |
|
|
|
709 |
root |
1.57 |
Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
710 |
|
|
be added, including other groups, as long as you do not create circular |
711 |
|
|
dependencies. |
712 |
|
|
|
713 |
|
|
Returns all its arguments. |
714 |
root |
1.55 |
|
715 |
root |
1.74 |
=item $grp->cancel_subs |
716 |
|
|
|
717 |
|
|
Cancel all subrequests and clears any feeder, but not the group request |
718 |
|
|
itself. Useful when you queued a lot of events but got a result early. |
719 |
|
|
|
720 |
root |
1.58 |
=item $grp->result (...) |
721 |
|
|
|
722 |
|
|
Set the result value(s) that will be passed to the group callback when all |
723 |
|
|
subrequests have finished. By default, no argument will be passed. |
724 |
|
|
|
725 |
root |
1.65 |
=item feed $grp $callback->($grp) |
726 |
root |
1.60 |
|
727 |
|
|
Sets a feeder/generator on this group: every group can have an attached |
728 |
|
|
generator that generates requests if idle. The idea behind this is that, |
729 |
|
|
although you could just queue as many requests as you want in a group, |
730 |
|
|
this might starve other requests for a potentially long time. For |
731 |
|
|
example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> |
732 |
|
|
requests, delaying any later requests for a long time. |
733 |
|
|
|
734 |
|
|
To avoid this, and allow incremental generation of requests, you can |
735 |
|
|
instead a group and set a feeder on it that generates those requests. The |
736 |
root |
1.68 |
feed callback will be called whenever there are few enough (see C<limit>, |
737 |
root |
1.60 |
below) requests active in the group itself and is expected to queue more |
738 |
|
|
requests. |
739 |
|
|
|
740 |
root |
1.68 |
The feed callback can queue as many requests as it likes (i.e. C<add> does |
741 |
|
|
not impose any limits). |
742 |
root |
1.60 |
|
743 |
root |
1.65 |
If the feed does not queue more requests when called, it will be |
744 |
root |
1.60 |
automatically removed from the group. |
745 |
|
|
|
746 |
root |
1.65 |
If the feed limit is C<0>, it will be set to C<2> automatically. |
747 |
root |
1.60 |
|
748 |
|
|
Example: |
749 |
|
|
|
750 |
|
|
# stat all files in @files, but only ever use four aio requests concurrently: |
751 |
|
|
|
752 |
|
|
my $grp = aio_group sub { print "finished\n" }; |
753 |
root |
1.68 |
limit $grp 4; |
754 |
root |
1.65 |
feed $grp sub { |
755 |
root |
1.60 |
my $file = pop @files |
756 |
|
|
or return; |
757 |
|
|
|
758 |
|
|
add $grp aio_stat $file, sub { ... }; |
759 |
root |
1.65 |
}; |
760 |
root |
1.60 |
|
761 |
root |
1.68 |
=item limit $grp $num |
762 |
root |
1.60 |
|
763 |
|
|
Sets the feeder limit for the group: The feeder will be called whenever |
764 |
|
|
the group contains less than this many requests. |
765 |
|
|
|
766 |
|
|
Setting the limit to C<0> will pause the feeding process. |
767 |
|
|
|
768 |
root |
1.55 |
=back |
769 |
|
|
|
770 |
root |
1.5 |
=head2 SUPPORT FUNCTIONS |
771 |
|
|
|
772 |
|
|
=over 4 |
773 |
|
|
|
774 |
|
|
=item $fileno = IO::AIO::poll_fileno |
775 |
|
|
|
776 |
root |
1.20 |
Return the I<request result pipe file descriptor>. This filehandle must be |
777 |
|
|
polled for reading by some mechanism outside this module (e.g. Event or |
778 |
|
|
select, see below or the SYNOPSIS). If the pipe becomes readable you have |
779 |
|
|
to call C<poll_cb> to check the results. |
780 |
root |
1.5 |
|
781 |
|
|
See C<poll_cb> for an example. |
782 |
|
|
|
783 |
|
|
=item IO::AIO::poll_cb |
784 |
|
|
|
785 |
|
|
Process all outstanding events on the result pipe. You have to call this |
786 |
|
|
regularly. Returns the number of events processed. Returns immediately |
787 |
|
|
when no events are outstanding. |
788 |
|
|
|
789 |
root |
1.20 |
Example: Install an Event watcher that automatically calls |
790 |
|
|
IO::AIO::poll_cb with high priority: |
791 |
root |
1.5 |
|
792 |
|
|
Event->io (fd => IO::AIO::poll_fileno, |
793 |
|
|
poll => 'r', async => 1, |
794 |
|
|
cb => \&IO::AIO::poll_cb); |
795 |
|
|
|
796 |
|
|
=item IO::AIO::poll_wait |
797 |
|
|
|
798 |
|
|
Wait till the result filehandle becomes ready for reading (simply does a |
799 |
root |
1.20 |
C<select> on the filehandle. This is useful if you want to synchronously wait |
800 |
root |
1.5 |
for some requests to finish). |
801 |
|
|
|
802 |
|
|
See C<nreqs> for an example. |
803 |
|
|
|
804 |
|
|
=item IO::AIO::nreqs |
805 |
|
|
|
806 |
root |
1.20 |
Returns the number of requests currently outstanding (i.e. for which their |
807 |
|
|
callback has not been invoked yet). |
808 |
root |
1.5 |
|
809 |
|
|
Example: wait till there are no outstanding requests anymore: |
810 |
|
|
|
811 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
812 |
|
|
while IO::AIO::nreqs; |
813 |
|
|
|
814 |
root |
1.12 |
=item IO::AIO::flush |
815 |
|
|
|
816 |
|
|
Wait till all outstanding AIO requests have been handled. |
817 |
|
|
|
818 |
root |
1.13 |
Strictly equivalent to: |
819 |
|
|
|
820 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
821 |
|
|
while IO::AIO::nreqs; |
822 |
|
|
|
823 |
|
|
=item IO::AIO::poll |
824 |
|
|
|
825 |
|
|
Waits until some requests have been handled. |
826 |
|
|
|
827 |
|
|
Strictly equivalent to: |
828 |
|
|
|
829 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
830 |
|
|
if IO::AIO::nreqs; |
831 |
|
|
|
832 |
root |
1.5 |
=item IO::AIO::min_parallel $nthreads |
833 |
|
|
|
834 |
root |
1.61 |
Set the minimum number of AIO threads to C<$nthreads>. The current |
835 |
|
|
default is C<8>, which means eight asynchronous operations can execute |
836 |
|
|
concurrently at any one time (the number of outstanding requests, |
837 |
|
|
however, is unlimited). |
838 |
root |
1.5 |
|
839 |
root |
1.34 |
IO::AIO starts threads only on demand, when an AIO request is queued and |
840 |
|
|
no free thread exists. |
841 |
|
|
|
842 |
root |
1.61 |
It is recommended to keep the number of threads relatively low, as some |
843 |
|
|
Linux kernel versions will scale negatively with the number of threads |
844 |
|
|
(higher parallelity => MUCH higher latency). With current Linux 2.6 |
845 |
|
|
versions, 4-32 threads should be fine. |
846 |
root |
1.5 |
|
847 |
root |
1.34 |
Under most circumstances you don't need to call this function, as the |
848 |
|
|
module selects a default that is suitable for low to moderate load. |
849 |
root |
1.5 |
|
850 |
|
|
=item IO::AIO::max_parallel $nthreads |
851 |
|
|
|
852 |
root |
1.34 |
Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
853 |
|
|
specified number of threads are currently running, this function kills |
854 |
|
|
them. This function blocks until the limit is reached. |
855 |
|
|
|
856 |
|
|
While C<$nthreads> are zero, aio requests get queued but not executed |
857 |
|
|
until the number of threads has been increased again. |
858 |
root |
1.5 |
|
859 |
|
|
This module automatically runs C<max_parallel 0> at program end, to ensure |
860 |
|
|
that all threads are killed and that there are no outstanding requests. |
861 |
|
|
|
862 |
|
|
Under normal circumstances you don't need to call this function. |
863 |
|
|
|
864 |
|
|
=item $oldnreqs = IO::AIO::max_outstanding $nreqs |
865 |
|
|
|
866 |
root |
1.62 |
[DEPRECATED] |
867 |
|
|
|
868 |
root |
1.5 |
Sets the maximum number of outstanding requests to C<$nreqs>. If you |
869 |
|
|
try to queue up more than this number of requests, the caller will block until |
870 |
|
|
some requests have been handled. |
871 |
|
|
|
872 |
|
|
The default is very large, so normally there is no practical limit. If you |
873 |
root |
1.34 |
queue up many requests in a loop it often improves speed if you set |
874 |
root |
1.5 |
this to a relatively low number, such as C<100>. |
875 |
|
|
|
876 |
root |
1.62 |
This function does not work well together with C<aio_group>'s, and their |
877 |
|
|
feeder interface is better suited to limiting concurrency, so do not use |
878 |
|
|
this function. |
879 |
|
|
|
880 |
root |
1.5 |
Under normal circumstances you don't need to call this function. |
881 |
|
|
|
882 |
|
|
=back |
883 |
|
|
|
884 |
root |
1.1 |
=cut |
885 |
|
|
|
886 |
root |
1.2 |
# support function to convert a fd into a perl filehandle |
887 |
|
|
sub _fd2fh { |
888 |
|
|
return undef if $_[0] < 0; |
889 |
|
|
|
890 |
root |
1.23 |
# try to generate nice filehandles |
891 |
|
|
my $sym = "IO::AIO::fd#$_[0]"; |
892 |
|
|
local *$sym; |
893 |
root |
1.25 |
|
894 |
root |
1.27 |
open *$sym, "+<&=$_[0]" # usually works under any unix |
895 |
|
|
or open *$sym, "<&=$_[0]" # cygwin needs this |
896 |
|
|
or open *$sym, ">&=$_[0]" # or this |
897 |
root |
1.2 |
or return undef; |
898 |
|
|
|
899 |
root |
1.23 |
*$sym |
900 |
root |
1.2 |
} |
901 |
|
|
|
902 |
root |
1.61 |
min_parallel 8; |
903 |
root |
1.1 |
|
904 |
|
|
END { |
905 |
|
|
max_parallel 0; |
906 |
|
|
} |
907 |
|
|
|
908 |
|
|
1; |
909 |
|
|
|
910 |
root |
1.27 |
=head2 FORK BEHAVIOUR |
911 |
|
|
|
912 |
root |
1.52 |
This module should do "the right thing" when the process using it forks: |
913 |
|
|
|
914 |
root |
1.34 |
Before the fork, IO::AIO enters a quiescent state where no requests |
915 |
|
|
can be added in other threads and no results will be processed. After |
916 |
|
|
the fork the parent simply leaves the quiescent state and continues |
917 |
root |
1.72 |
request/result processing, while the child frees the request/result queue |
918 |
|
|
(so that the requests started before the fork will only be handled in the |
919 |
|
|
parent). Threads will be started on demand until the limit set in the |
920 |
root |
1.34 |
parent process has been reached again. |
921 |
root |
1.27 |
|
922 |
root |
1.52 |
In short: the parent will, after a short pause, continue as if fork had |
923 |
|
|
not been called, while the child will act as if IO::AIO has not been used |
924 |
|
|
yet. |
925 |
|
|
|
926 |
root |
1.60 |
=head2 MEMORY USAGE |
927 |
|
|
|
928 |
root |
1.72 |
Per-request usage: |
929 |
|
|
|
930 |
|
|
Each aio request uses - depending on your architecture - around 100-200 |
931 |
|
|
bytes of memory. In addition, stat requests need a stat buffer (possibly |
932 |
|
|
a few hundred bytes), readdir requires a result buffer and so on. Perl |
933 |
|
|
scalars and other data passed into aio requests will also be locked and |
934 |
|
|
will consume memory till the request has entered the done state. |
935 |
root |
1.60 |
|
936 |
|
|
This is now awfully much, so queuing lots of requests is not usually a |
937 |
|
|
problem. |
938 |
|
|
|
939 |
root |
1.72 |
Per-thread usage: |
940 |
|
|
|
941 |
|
|
In the execution phase, some aio requests require more memory for |
942 |
|
|
temporary buffers, and each thread requires a stack and other data |
943 |
|
|
structures (usually around 16k-128k, depending on the OS). |
944 |
|
|
|
945 |
|
|
=head1 KNOWN BUGS |
946 |
|
|
|
947 |
root |
1.73 |
Known bugs will be fixed in the next release. |
948 |
root |
1.60 |
|
949 |
root |
1.1 |
=head1 SEE ALSO |
950 |
|
|
|
951 |
root |
1.68 |
L<Coro::AIO>. |
952 |
root |
1.1 |
|
953 |
|
|
=head1 AUTHOR |
954 |
|
|
|
955 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
956 |
|
|
http://home.schmorp.de/ |
957 |
|
|
|
958 |
|
|
=cut |
959 |
|
|
|