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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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1.94 |
my $fh = shift |
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or die "/etc/passwd: $!"; |
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1.6 |
... |
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}; |
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aio_unlink "/tmp/file", sub { }; |
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aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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$_[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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|
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aioreq_pri 4; # give next request a very high priority |
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my $req = aio_unlink "/tmp/file", sub { }; |
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$req->cancel; # cancel request if still in queue |
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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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Event->io (fd => IO::AIO::poll_fileno, |
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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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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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1.85 |
Asynchronous means that operations that can normally block your program |
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(e.g. reading from disk) will be done asynchronously: the operation |
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will still block, but you can do something else in the meantime. This |
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is extremely useful for programs that need to stay interactive even |
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when doing heavy I/O (GUI programs, high performance network servers |
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etc.), but can also be used to easily do operations in parallel that are |
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normally done sequentially, e.g. stat'ing many files, which is much faster |
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on a RAID volume or over NFS when you do a number of stat operations |
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concurrently. |
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1.90 |
While most of this works on all types of file descriptors (for example |
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sockets), using these functions on file descriptors that support |
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nonblocking operation (again, sockets, pipes etc.) is very inefficient or |
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might not work (aio_read fails on sockets/pipes/fifos). Use an event loop |
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for that (such as the L<Event|Event> module): IO::AIO will naturally fit |
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into such an event loop itself. |
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1.85 |
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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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1.85 |
not well-supported or restricted (GNU/Linux doesn't allow them on normal |
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1.72 |
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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1.86 |
=head2 EXAMPLE |
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This is a simple example that uses the Event module and loads |
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F</etc/passwd> asynchronously: |
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use Fcntl; |
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use Event; |
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use IO::AIO; |
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# register the IO::AIO callback with Event |
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Event->io (fd => IO::AIO::poll_fileno, |
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poll => 'r', |
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cb => \&IO::AIO::poll_cb); |
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# queue the request to open /etc/passwd |
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aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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1.94 |
my $fh = shift |
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1.86 |
or die "error while opening: $!"; |
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# stat'ing filehandles is generally non-blocking |
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my $size = -s $fh; |
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# queue a request to read the file |
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my $contents; |
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aio_read $fh, 0, $size, $contents, 0, sub { |
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$_[0] == $size |
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or die "short read: $!"; |
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close $fh; |
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# file contents now in $contents |
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print $contents; |
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# exit event loop and program |
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Event::unloop; |
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}; |
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}; |
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# possibly queue up other requests, or open GUI windows, |
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# check for sockets etc. etc. |
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# process events as long as there are some: |
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Event::loop; |
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1.72 |
=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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1.88 |
=back |
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1.1 |
=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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1.103 |
our $VERSION = '2.33'; |
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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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1.90 |
aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link |
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1.101 |
aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir); |
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1.95 |
our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block)); |
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1.67 |
our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
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1.86 |
min_parallel max_parallel max_idle |
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nreqs nready npending nthreads |
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max_poll_time max_poll_reqs); |
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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", $VERSION); |
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1.1 |
} |
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1.5 |
=head1 FUNCTIONS |
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1.1 |
|
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1.87 |
=head2 AIO REQUEST FUNCTIONS |
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1.1 |
|
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1.5 |
All the C<aio_*> calls are more or less thin wrappers around the syscall |
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with the same name (sans C<aio_>). The arguments are similar or identical, |
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1.14 |
and they all accept an additional (and optional) C<$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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1.87 |
All functions return request objects of type L<IO::AIO::REQ> that allow |
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further 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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1.87 |
encoded as octets. The reason for the former is that at the time the |
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1.28 |
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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1.87 |
current working directory anywhere in the program and then use relative |
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paths. |
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1.28 |
|
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1.87 |
To encode pathnames as octets, either make sure you either: a) always pass |
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in filenames you got from outside (command line, readdir etc.) without |
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tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode |
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1.28 |
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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1.87 |
use something else to ensure your scalar has the correct contents. |
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This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
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handles correctly wether it is set or not. |
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1.1 |
|
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1.5 |
=over 4 |
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1.1 |
|
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1.80 |
=item $prev_pri = aioreq_pri [$pri] |
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1.68 |
|
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1.80 |
Returns the priority value that would be used for the next request and, if |
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C<$pri> is given, sets the priority for the next aio request. |
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1.68 |
|
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1.80 |
The default priority is C<0>, the minimum and maximum priorities are C<-4> |
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and C<4>, respectively. Requests with higher priority will be serviced |
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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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1.68 |
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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1.87 |
priority, so the effect is cumulative. |
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1.69 |
|
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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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1.101 |
and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified |
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by the umask in effect then the request is being executed, so better never |
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change the umask. |
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1.1 |
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Example: |
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301 |
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aio_open "/etc/passwd", O_RDONLY, 0, sub { |
302 |
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1.2 |
if ($_[0]) { |
303 |
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print "open successful, fh is $_[0]\n"; |
304 |
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1.1 |
... |
305 |
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} else { |
306 |
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die "open failed: $!\n"; |
307 |
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} |
308 |
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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 |
313 |
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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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|
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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> |
326 |
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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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|
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1.31 |
The C<$data> scalar I<MUST NOT> be modified in any way while the request |
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is outstanding. Modifying it can result in segfaults or WW3 (if the |
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necessary/optional hardware is installed). |
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|
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1.17 |
Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
335 |
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1.1 |
offset C<0> within the scalar: |
336 |
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|
337 |
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aio_read $fh, 7, 15, $buffer, 0, sub { |
338 |
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1.9 |
$_[0] > 0 or die "read error: $!"; |
339 |
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print "read $_[0] bytes: <$buffer>\n"; |
340 |
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1.1 |
}; |
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|
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1.40 |
=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
343 |
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1.35 |
|
344 |
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Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts |
345 |
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reading at byte offset C<$in_offset>, and starts writing at the current |
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file offset of C<$out_fh>. Because of that, it is not safe to issue more |
347 |
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than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each |
348 |
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other. |
349 |
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|
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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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|
|
354 |
|
|
If the native sendfile call fails or is not implemented, it will be |
355 |
root |
1.36 |
emulated, so you can call C<aio_sendfile> on any type of filehandle |
356 |
|
|
regardless of the limitations of the operating system. |
357 |
root |
1.35 |
|
358 |
|
|
Please note, however, that C<aio_sendfile> can read more bytes from |
359 |
|
|
C<$in_fh> than are written, and there is no way to find out how many |
360 |
root |
1.36 |
bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only |
361 |
|
|
provides the number of bytes written to C<$out_fh>. Only if the result |
362 |
|
|
value equals C<$length> one can assume that C<$length> bytes have been |
363 |
|
|
read. |
364 |
root |
1.35 |
|
365 |
root |
1.40 |
=item aio_readahead $fh,$offset,$length, $callback->($retval) |
366 |
root |
1.1 |
|
367 |
root |
1.20 |
C<aio_readahead> populates the page cache with data from a file so that |
368 |
root |
1.1 |
subsequent reads from that file will not block on disk I/O. The C<$offset> |
369 |
|
|
argument specifies the starting point from which data is to be read and |
370 |
|
|
C<$length> specifies the number of bytes to be read. I/O is performed in |
371 |
|
|
whole pages, so that offset is effectively rounded down to a page boundary |
372 |
|
|
and bytes are read up to the next page boundary greater than or equal to |
373 |
root |
1.20 |
(off-set+length). C<aio_readahead> does not read beyond the end of the |
374 |
root |
1.1 |
file. The current file offset of the file is left unchanged. |
375 |
|
|
|
376 |
root |
1.26 |
If that syscall doesn't exist (likely if your OS isn't Linux) it will be |
377 |
|
|
emulated by simply reading the data, which would have a similar effect. |
378 |
|
|
|
379 |
root |
1.40 |
=item aio_stat $fh_or_path, $callback->($status) |
380 |
root |
1.1 |
|
381 |
root |
1.40 |
=item aio_lstat $fh, $callback->($status) |
382 |
root |
1.1 |
|
383 |
|
|
Works like perl's C<stat> or C<lstat> in void context. The callback will |
384 |
|
|
be called after the stat and the results will be available using C<stat _> |
385 |
|
|
or C<-s _> etc... |
386 |
|
|
|
387 |
|
|
The pathname passed to C<aio_stat> must be absolute. See API NOTES, above, |
388 |
|
|
for an explanation. |
389 |
|
|
|
390 |
|
|
Currently, the stats are always 64-bit-stats, i.e. instead of returning an |
391 |
|
|
error when stat'ing a large file, the results will be silently truncated |
392 |
|
|
unless perl itself is compiled with large file support. |
393 |
|
|
|
394 |
|
|
Example: Print the length of F</etc/passwd>: |
395 |
|
|
|
396 |
|
|
aio_stat "/etc/passwd", sub { |
397 |
|
|
$_[0] and die "stat failed: $!"; |
398 |
|
|
print "size is ", -s _, "\n"; |
399 |
|
|
}; |
400 |
|
|
|
401 |
root |
1.40 |
=item aio_unlink $pathname, $callback->($status) |
402 |
root |
1.1 |
|
403 |
|
|
Asynchronously unlink (delete) a file and call the callback with the |
404 |
|
|
result code. |
405 |
|
|
|
406 |
root |
1.82 |
=item aio_mknod $path, $mode, $dev, $callback->($status) |
407 |
|
|
|
408 |
root |
1.86 |
[EXPERIMENTAL] |
409 |
|
|
|
410 |
root |
1.83 |
Asynchronously create a device node (or fifo). See mknod(2). |
411 |
|
|
|
412 |
root |
1.86 |
The only (POSIX-) portable way of calling this function is: |
413 |
root |
1.83 |
|
414 |
|
|
aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
415 |
root |
1.82 |
|
416 |
root |
1.50 |
=item aio_link $srcpath, $dstpath, $callback->($status) |
417 |
|
|
|
418 |
|
|
Asynchronously create a new link to the existing object at C<$srcpath> at |
419 |
|
|
the path C<$dstpath> and call the callback with the result code. |
420 |
|
|
|
421 |
|
|
=item aio_symlink $srcpath, $dstpath, $callback->($status) |
422 |
|
|
|
423 |
|
|
Asynchronously create a new symbolic link to the existing object at C<$srcpath> at |
424 |
|
|
the path C<$dstpath> and call the callback with the result code. |
425 |
|
|
|
426 |
root |
1.90 |
=item aio_readlink $path, $callback->($link) |
427 |
|
|
|
428 |
|
|
Asynchronously read the symlink specified by C<$path> and pass it to |
429 |
|
|
the callback. If an error occurs, nothing or undef gets passed to the |
430 |
|
|
callback. |
431 |
|
|
|
432 |
root |
1.50 |
=item aio_rename $srcpath, $dstpath, $callback->($status) |
433 |
|
|
|
434 |
|
|
Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as |
435 |
|
|
rename(2) and call the callback with the result code. |
436 |
|
|
|
437 |
root |
1.101 |
=item aio_mkdir $pathname, $mode, $callback->($status) |
438 |
|
|
|
439 |
|
|
Asynchronously mkdir (create) a directory and call the callback with |
440 |
|
|
the result code. C<$mode> will be modified by the umask at the time the |
441 |
|
|
request is executed, so do not change your umask. |
442 |
|
|
|
443 |
root |
1.40 |
=item aio_rmdir $pathname, $callback->($status) |
444 |
root |
1.27 |
|
445 |
|
|
Asynchronously rmdir (delete) a directory and call the callback with the |
446 |
|
|
result code. |
447 |
|
|
|
448 |
root |
1.46 |
=item aio_readdir $pathname, $callback->($entries) |
449 |
root |
1.37 |
|
450 |
|
|
Unlike the POSIX call of the same name, C<aio_readdir> reads an entire |
451 |
|
|
directory (i.e. opendir + readdir + closedir). The entries will not be |
452 |
|
|
sorted, and will B<NOT> include the C<.> and C<..> entries. |
453 |
|
|
|
454 |
|
|
The callback a single argument which is either C<undef> or an array-ref |
455 |
|
|
with the filenames. |
456 |
|
|
|
457 |
root |
1.98 |
=item aio_load $path, $data, $callback->($status) |
458 |
|
|
|
459 |
|
|
This is a composite request that tries to fully load the given file into |
460 |
|
|
memory. Status is the same as with aio_read. |
461 |
|
|
|
462 |
|
|
=cut |
463 |
|
|
|
464 |
|
|
sub aio_load($$;$) { |
465 |
|
|
aio_block { |
466 |
|
|
my ($path, undef, $cb) = @_; |
467 |
|
|
my $data = \$_[1]; |
468 |
|
|
|
469 |
|
|
my $pri = aioreq_pri; |
470 |
|
|
my $grp = aio_group $cb; |
471 |
|
|
|
472 |
|
|
aioreq_pri $pri; |
473 |
|
|
add $grp aio_open $path, O_RDONLY, 0, sub { |
474 |
root |
1.102 |
my $fh = shift |
475 |
root |
1.98 |
or return $grp->result (-1); |
476 |
|
|
|
477 |
|
|
aioreq_pri $pri; |
478 |
|
|
add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { |
479 |
|
|
$grp->result ($_[0]); |
480 |
|
|
}; |
481 |
|
|
}; |
482 |
|
|
|
483 |
|
|
$grp |
484 |
|
|
} |
485 |
|
|
} |
486 |
|
|
|
487 |
root |
1.82 |
=item aio_copy $srcpath, $dstpath, $callback->($status) |
488 |
|
|
|
489 |
|
|
Try to copy the I<file> (directories not supported as either source or |
490 |
|
|
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
491 |
|
|
the C<0> (error) or C<-1> ok. |
492 |
|
|
|
493 |
|
|
This is a composite request that it creates the destination file with |
494 |
|
|
mode 0200 and copies the contents of the source file into it using |
495 |
|
|
C<aio_sendfile>, followed by restoring atime, mtime, access mode and |
496 |
|
|
uid/gid, in that order. |
497 |
|
|
|
498 |
|
|
If an error occurs, the partial destination file will be unlinked, if |
499 |
|
|
possible, except when setting atime, mtime, access mode and uid/gid, where |
500 |
|
|
errors are being ignored. |
501 |
|
|
|
502 |
|
|
=cut |
503 |
|
|
|
504 |
|
|
sub aio_copy($$;$) { |
505 |
root |
1.95 |
aio_block { |
506 |
|
|
my ($src, $dst, $cb) = @_; |
507 |
root |
1.82 |
|
508 |
root |
1.95 |
my $pri = aioreq_pri; |
509 |
|
|
my $grp = aio_group $cb; |
510 |
root |
1.82 |
|
511 |
root |
1.95 |
aioreq_pri $pri; |
512 |
|
|
add $grp aio_open $src, O_RDONLY, 0, sub { |
513 |
|
|
if (my $src_fh = $_[0]) { |
514 |
|
|
my @stat = stat $src_fh; |
515 |
|
|
|
516 |
|
|
aioreq_pri $pri; |
517 |
|
|
add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { |
518 |
|
|
if (my $dst_fh = $_[0]) { |
519 |
|
|
aioreq_pri $pri; |
520 |
|
|
add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { |
521 |
|
|
if ($_[0] == $stat[7]) { |
522 |
|
|
$grp->result (0); |
523 |
|
|
close $src_fh; |
524 |
|
|
|
525 |
|
|
# those should not normally block. should. should. |
526 |
|
|
utime $stat[8], $stat[9], $dst; |
527 |
|
|
chmod $stat[2] & 07777, $dst_fh; |
528 |
|
|
chown $stat[4], $stat[5], $dst_fh; |
529 |
|
|
close $dst_fh; |
530 |
|
|
} else { |
531 |
|
|
$grp->result (-1); |
532 |
|
|
close $src_fh; |
533 |
|
|
close $dst_fh; |
534 |
root |
1.82 |
|
535 |
root |
1.95 |
aioreq $pri; |
536 |
|
|
add $grp aio_unlink $dst; |
537 |
|
|
} |
538 |
|
|
}; |
539 |
|
|
} else { |
540 |
|
|
$grp->result (-1); |
541 |
|
|
} |
542 |
|
|
}, |
543 |
|
|
|
544 |
|
|
} else { |
545 |
|
|
$grp->result (-1); |
546 |
|
|
} |
547 |
|
|
}; |
548 |
root |
1.82 |
|
549 |
root |
1.95 |
$grp |
550 |
|
|
} |
551 |
root |
1.82 |
} |
552 |
|
|
|
553 |
|
|
=item aio_move $srcpath, $dstpath, $callback->($status) |
554 |
|
|
|
555 |
|
|
Try to move the I<file> (directories not supported as either source or |
556 |
|
|
destination) from C<$srcpath> to C<$dstpath> and call the callback with |
557 |
|
|
the C<0> (error) or C<-1> ok. |
558 |
|
|
|
559 |
|
|
This is a composite request that tries to rename(2) the file first. If |
560 |
|
|
rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if |
561 |
|
|
that is successful, unlinking the C<$srcpath>. |
562 |
|
|
|
563 |
|
|
=cut |
564 |
|
|
|
565 |
|
|
sub aio_move($$;$) { |
566 |
root |
1.95 |
aio_block { |
567 |
|
|
my ($src, $dst, $cb) = @_; |
568 |
root |
1.82 |
|
569 |
root |
1.95 |
my $pri = aioreq_pri; |
570 |
|
|
my $grp = aio_group $cb; |
571 |
root |
1.82 |
|
572 |
root |
1.95 |
aioreq_pri $pri; |
573 |
|
|
add $grp aio_rename $src, $dst, sub { |
574 |
|
|
if ($_[0] && $! == EXDEV) { |
575 |
|
|
aioreq_pri $pri; |
576 |
|
|
add $grp aio_copy $src, $dst, sub { |
577 |
|
|
$grp->result ($_[0]); |
578 |
|
|
|
579 |
|
|
if (!$_[0]) { |
580 |
|
|
aioreq_pri $pri; |
581 |
|
|
add $grp aio_unlink $src; |
582 |
|
|
} |
583 |
|
|
}; |
584 |
|
|
} else { |
585 |
root |
1.82 |
$grp->result ($_[0]); |
586 |
root |
1.95 |
} |
587 |
|
|
}; |
588 |
root |
1.82 |
|
589 |
root |
1.95 |
$grp |
590 |
|
|
} |
591 |
root |
1.82 |
} |
592 |
|
|
|
593 |
root |
1.40 |
=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
594 |
|
|
|
595 |
root |
1.52 |
Scans a directory (similar to C<aio_readdir>) but additionally tries to |
596 |
root |
1.76 |
efficiently separate the entries of directory C<$path> into two sets of |
597 |
|
|
names, directories you can recurse into (directories), and ones you cannot |
598 |
|
|
recurse into (everything else, including symlinks to directories). |
599 |
root |
1.52 |
|
600 |
root |
1.61 |
C<aio_scandir> is a composite request that creates of many sub requests_ |
601 |
|
|
C<$maxreq> specifies the maximum number of outstanding aio requests that |
602 |
|
|
this function generates. If it is C<< <= 0 >>, then a suitable default |
603 |
root |
1.81 |
will be chosen (currently 4). |
604 |
root |
1.40 |
|
605 |
|
|
On error, the callback is called without arguments, otherwise it receives |
606 |
|
|
two array-refs with path-relative entry names. |
607 |
|
|
|
608 |
|
|
Example: |
609 |
|
|
|
610 |
|
|
aio_scandir $dir, 0, sub { |
611 |
|
|
my ($dirs, $nondirs) = @_; |
612 |
|
|
print "real directories: @$dirs\n"; |
613 |
|
|
print "everything else: @$nondirs\n"; |
614 |
|
|
}; |
615 |
|
|
|
616 |
|
|
Implementation notes. |
617 |
|
|
|
618 |
|
|
The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can. |
619 |
|
|
|
620 |
|
|
After reading the directory, the modification time, size etc. of the |
621 |
root |
1.52 |
directory before and after the readdir is checked, and if they match (and |
622 |
|
|
isn't the current time), the link count will be used to decide how many |
623 |
|
|
entries are directories (if >= 2). Otherwise, no knowledge of the number |
624 |
|
|
of subdirectories will be assumed. |
625 |
|
|
|
626 |
|
|
Then entries will be sorted into likely directories (everything without |
627 |
|
|
a non-initial dot currently) and likely non-directories (everything |
628 |
|
|
else). Then every entry plus an appended C</.> will be C<stat>'ed, |
629 |
|
|
likely directories first. If that succeeds, it assumes that the entry |
630 |
|
|
is a directory or a symlink to directory (which will be checked |
631 |
|
|
seperately). This is often faster than stat'ing the entry itself because |
632 |
|
|
filesystems might detect the type of the entry without reading the inode |
633 |
|
|
data (e.g. ext2fs filetype feature). |
634 |
|
|
|
635 |
|
|
If the known number of directories (link count - 2) has been reached, the |
636 |
|
|
rest of the entries is assumed to be non-directories. |
637 |
|
|
|
638 |
|
|
This only works with certainty on POSIX (= UNIX) filesystems, which |
639 |
|
|
fortunately are the vast majority of filesystems around. |
640 |
|
|
|
641 |
|
|
It will also likely work on non-POSIX filesystems with reduced efficiency |
642 |
|
|
as those tend to return 0 or 1 as link counts, which disables the |
643 |
|
|
directory counting heuristic. |
644 |
root |
1.40 |
|
645 |
|
|
=cut |
646 |
|
|
|
647 |
root |
1.100 |
sub aio_scandir($$;$) { |
648 |
root |
1.95 |
aio_block { |
649 |
|
|
my ($path, $maxreq, $cb) = @_; |
650 |
root |
1.40 |
|
651 |
root |
1.95 |
my $pri = aioreq_pri; |
652 |
root |
1.80 |
|
653 |
root |
1.95 |
my $grp = aio_group $cb; |
654 |
root |
1.55 |
|
655 |
root |
1.95 |
$maxreq = 4 if $maxreq <= 0; |
656 |
root |
1.40 |
|
657 |
root |
1.95 |
# stat once |
658 |
root |
1.80 |
aioreq_pri $pri; |
659 |
root |
1.95 |
add $grp aio_stat $path, sub { |
660 |
|
|
return $grp->result () if $_[0]; |
661 |
|
|
my $now = time; |
662 |
|
|
my $hash1 = join ":", (stat _)[0,1,3,7,9]; |
663 |
root |
1.40 |
|
664 |
root |
1.95 |
# read the directory entries |
665 |
root |
1.80 |
aioreq_pri $pri; |
666 |
root |
1.95 |
add $grp aio_readdir $path, sub { |
667 |
|
|
my $entries = shift |
668 |
|
|
or return $grp->result (); |
669 |
|
|
|
670 |
|
|
# stat the dir another time |
671 |
|
|
aioreq_pri $pri; |
672 |
|
|
add $grp aio_stat $path, sub { |
673 |
|
|
my $hash2 = join ":", (stat _)[0,1,3,7,9]; |
674 |
|
|
|
675 |
|
|
my $ndirs; |
676 |
|
|
|
677 |
|
|
# take the slow route if anything looks fishy |
678 |
|
|
if ($hash1 ne $hash2 or (stat _)[9] == $now) { |
679 |
|
|
$ndirs = -1; |
680 |
|
|
} else { |
681 |
|
|
# if nlink == 2, we are finished |
682 |
|
|
# on non-posix-fs's, we rely on nlink < 2 |
683 |
|
|
$ndirs = (stat _)[3] - 2 |
684 |
|
|
or return $grp->result ([], $entries); |
685 |
|
|
} |
686 |
|
|
|
687 |
|
|
# sort into likely dirs and likely nondirs |
688 |
|
|
# dirs == files without ".", short entries first |
689 |
|
|
$entries = [map $_->[0], |
690 |
|
|
sort { $b->[1] cmp $a->[1] } |
691 |
|
|
map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], |
692 |
|
|
@$entries]; |
693 |
root |
1.40 |
|
694 |
root |
1.95 |
my (@dirs, @nondirs); |
695 |
root |
1.40 |
|
696 |
root |
1.95 |
my $statgrp = add $grp aio_group sub { |
697 |
|
|
$grp->result (\@dirs, \@nondirs); |
698 |
|
|
}; |
699 |
root |
1.40 |
|
700 |
root |
1.95 |
limit $statgrp $maxreq; |
701 |
|
|
feed $statgrp sub { |
702 |
|
|
return unless @$entries; |
703 |
|
|
my $entry = pop @$entries; |
704 |
|
|
|
705 |
|
|
aioreq_pri $pri; |
706 |
|
|
add $statgrp aio_stat "$path/$entry/.", sub { |
707 |
|
|
if ($_[0] < 0) { |
708 |
|
|
push @nondirs, $entry; |
709 |
|
|
} else { |
710 |
|
|
# need to check for real directory |
711 |
|
|
aioreq_pri $pri; |
712 |
|
|
add $statgrp aio_lstat "$path/$entry", sub { |
713 |
|
|
if (-d _) { |
714 |
|
|
push @dirs, $entry; |
715 |
|
|
|
716 |
|
|
unless (--$ndirs) { |
717 |
|
|
push @nondirs, @$entries; |
718 |
|
|
feed $statgrp; |
719 |
|
|
} |
720 |
|
|
} else { |
721 |
|
|
push @nondirs, $entry; |
722 |
root |
1.74 |
} |
723 |
root |
1.40 |
} |
724 |
|
|
} |
725 |
root |
1.95 |
}; |
726 |
root |
1.74 |
}; |
727 |
root |
1.40 |
}; |
728 |
|
|
}; |
729 |
|
|
}; |
730 |
root |
1.55 |
|
731 |
root |
1.95 |
$grp |
732 |
|
|
} |
733 |
root |
1.40 |
} |
734 |
|
|
|
735 |
root |
1.99 |
=item aio_rmtree $path, $callback->($status) |
736 |
|
|
|
737 |
root |
1.100 |
Delete a directory tree starting (and including) C<$path>, return the |
738 |
|
|
status of the final C<rmdir> only. This is a composite request that |
739 |
|
|
uses C<aio_scandir> to recurse into and rmdir directories, and unlink |
740 |
|
|
everything else. |
741 |
root |
1.99 |
|
742 |
|
|
=cut |
743 |
|
|
|
744 |
|
|
sub aio_rmtree; |
745 |
root |
1.100 |
sub aio_rmtree($;$) { |
746 |
root |
1.99 |
aio_block { |
747 |
|
|
my ($path, $cb) = @_; |
748 |
|
|
|
749 |
|
|
my $pri = aioreq_pri; |
750 |
|
|
my $grp = aio_group $cb; |
751 |
|
|
|
752 |
|
|
aioreq_pri $pri; |
753 |
|
|
add $grp aio_scandir $path, 0, sub { |
754 |
|
|
my ($dirs, $nondirs) = @_; |
755 |
|
|
|
756 |
|
|
my $dirgrp = aio_group sub { |
757 |
|
|
add $grp aio_rmdir $path, sub { |
758 |
|
|
$grp->result ($_[0]); |
759 |
|
|
}; |
760 |
|
|
}; |
761 |
|
|
|
762 |
|
|
(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; |
763 |
|
|
(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; |
764 |
|
|
|
765 |
|
|
add $grp $dirgrp; |
766 |
|
|
}; |
767 |
|
|
|
768 |
|
|
$grp |
769 |
|
|
} |
770 |
|
|
} |
771 |
|
|
|
772 |
root |
1.40 |
=item aio_fsync $fh, $callback->($status) |
773 |
root |
1.1 |
|
774 |
|
|
Asynchronously call fsync on the given filehandle and call the callback |
775 |
|
|
with the fsync result code. |
776 |
|
|
|
777 |
root |
1.40 |
=item aio_fdatasync $fh, $callback->($status) |
778 |
root |
1.1 |
|
779 |
|
|
Asynchronously call fdatasync on the given filehandle and call the |
780 |
root |
1.26 |
callback with the fdatasync result code. |
781 |
|
|
|
782 |
|
|
If this call isn't available because your OS lacks it or it couldn't be |
783 |
|
|
detected, it will be emulated by calling C<fsync> instead. |
784 |
root |
1.1 |
|
785 |
root |
1.58 |
=item aio_group $callback->(...) |
786 |
root |
1.54 |
|
787 |
root |
1.55 |
This is a very special aio request: Instead of doing something, it is a |
788 |
|
|
container for other aio requests, which is useful if you want to bundle |
789 |
root |
1.71 |
many requests into a single, composite, request with a definite callback |
790 |
|
|
and the ability to cancel the whole request with its subrequests. |
791 |
root |
1.55 |
|
792 |
|
|
Returns an object of class L<IO::AIO::GRP>. See its documentation below |
793 |
|
|
for more info. |
794 |
|
|
|
795 |
|
|
Example: |
796 |
|
|
|
797 |
|
|
my $grp = aio_group sub { |
798 |
|
|
print "all stats done\n"; |
799 |
|
|
}; |
800 |
|
|
|
801 |
|
|
add $grp |
802 |
|
|
(aio_stat ...), |
803 |
|
|
(aio_stat ...), |
804 |
|
|
...; |
805 |
|
|
|
806 |
root |
1.63 |
=item aio_nop $callback->() |
807 |
|
|
|
808 |
|
|
This is a special request - it does nothing in itself and is only used for |
809 |
|
|
side effects, such as when you want to add a dummy request to a group so |
810 |
|
|
that finishing the requests in the group depends on executing the given |
811 |
|
|
code. |
812 |
|
|
|
813 |
root |
1.64 |
While this request does nothing, it still goes through the execution |
814 |
|
|
phase and still requires a worker thread. Thus, the callback will not |
815 |
|
|
be executed immediately but only after other requests in the queue have |
816 |
|
|
entered their execution phase. This can be used to measure request |
817 |
|
|
latency. |
818 |
|
|
|
819 |
root |
1.71 |
=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
820 |
root |
1.54 |
|
821 |
|
|
Mainly used for debugging and benchmarking, this aio request puts one of |
822 |
|
|
the request workers to sleep for the given time. |
823 |
|
|
|
824 |
root |
1.56 |
While it is theoretically handy to have simple I/O scheduling requests |
825 |
root |
1.71 |
like sleep and file handle readable/writable, the overhead this creates is |
826 |
|
|
immense (it blocks a thread for a long time) so do not use this function |
827 |
|
|
except to put your application under artificial I/O pressure. |
828 |
root |
1.56 |
|
829 |
root |
1.5 |
=back |
830 |
|
|
|
831 |
root |
1.53 |
=head2 IO::AIO::REQ CLASS |
832 |
root |
1.52 |
|
833 |
|
|
All non-aggregate C<aio_*> functions return an object of this class when |
834 |
|
|
called in non-void context. |
835 |
|
|
|
836 |
|
|
=over 4 |
837 |
|
|
|
838 |
root |
1.65 |
=item cancel $req |
839 |
root |
1.52 |
|
840 |
|
|
Cancels the request, if possible. Has the effect of skipping execution |
841 |
|
|
when entering the B<execute> state and skipping calling the callback when |
842 |
|
|
entering the the B<result> state, but will leave the request otherwise |
843 |
|
|
untouched. That means that requests that currently execute will not be |
844 |
|
|
stopped and resources held by the request will not be freed prematurely. |
845 |
|
|
|
846 |
root |
1.65 |
=item cb $req $callback->(...) |
847 |
|
|
|
848 |
|
|
Replace (or simply set) the callback registered to the request. |
849 |
|
|
|
850 |
root |
1.52 |
=back |
851 |
|
|
|
852 |
root |
1.55 |
=head2 IO::AIO::GRP CLASS |
853 |
|
|
|
854 |
|
|
This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
855 |
|
|
objects of this class, too. |
856 |
|
|
|
857 |
|
|
A IO::AIO::GRP object is a special request that can contain multiple other |
858 |
|
|
aio requests. |
859 |
|
|
|
860 |
|
|
You create one by calling the C<aio_group> constructing function with a |
861 |
|
|
callback that will be called when all contained requests have entered the |
862 |
|
|
C<done> state: |
863 |
|
|
|
864 |
|
|
my $grp = aio_group sub { |
865 |
|
|
print "all requests are done\n"; |
866 |
|
|
}; |
867 |
|
|
|
868 |
|
|
You add requests by calling the C<add> method with one or more |
869 |
|
|
C<IO::AIO::REQ> objects: |
870 |
|
|
|
871 |
|
|
$grp->add (aio_unlink "..."); |
872 |
|
|
|
873 |
root |
1.58 |
add $grp aio_stat "...", sub { |
874 |
|
|
$_[0] or return $grp->result ("error"); |
875 |
|
|
|
876 |
|
|
# add another request dynamically, if first succeeded |
877 |
|
|
add $grp aio_open "...", sub { |
878 |
|
|
$grp->result ("ok"); |
879 |
|
|
}; |
880 |
|
|
}; |
881 |
root |
1.55 |
|
882 |
|
|
This makes it very easy to create composite requests (see the source of |
883 |
|
|
C<aio_move> for an application) that work and feel like simple requests. |
884 |
|
|
|
885 |
root |
1.62 |
=over 4 |
886 |
|
|
|
887 |
|
|
=item * The IO::AIO::GRP objects will be cleaned up during calls to |
888 |
root |
1.55 |
C<IO::AIO::poll_cb>, just like any other request. |
889 |
|
|
|
890 |
root |
1.62 |
=item * They can be canceled like any other request. Canceling will cancel not |
891 |
root |
1.59 |
only the request itself, but also all requests it contains. |
892 |
root |
1.55 |
|
893 |
root |
1.62 |
=item * They can also can also be added to other IO::AIO::GRP objects. |
894 |
root |
1.55 |
|
895 |
root |
1.62 |
=item * You must not add requests to a group from within the group callback (or |
896 |
root |
1.60 |
any later time). |
897 |
|
|
|
898 |
root |
1.62 |
=back |
899 |
|
|
|
900 |
root |
1.55 |
Their lifetime, simplified, looks like this: when they are empty, they |
901 |
|
|
will finish very quickly. If they contain only requests that are in the |
902 |
|
|
C<done> state, they will also finish. Otherwise they will continue to |
903 |
|
|
exist. |
904 |
|
|
|
905 |
root |
1.57 |
That means after creating a group you have some time to add requests. And |
906 |
|
|
in the callbacks of those requests, you can add further requests to the |
907 |
|
|
group. And only when all those requests have finished will the the group |
908 |
|
|
itself finish. |
909 |
|
|
|
910 |
root |
1.55 |
=over 4 |
911 |
|
|
|
912 |
root |
1.65 |
=item add $grp ... |
913 |
|
|
|
914 |
root |
1.55 |
=item $grp->add (...) |
915 |
|
|
|
916 |
root |
1.57 |
Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
917 |
|
|
be added, including other groups, as long as you do not create circular |
918 |
|
|
dependencies. |
919 |
|
|
|
920 |
|
|
Returns all its arguments. |
921 |
root |
1.55 |
|
922 |
root |
1.74 |
=item $grp->cancel_subs |
923 |
|
|
|
924 |
|
|
Cancel all subrequests and clears any feeder, but not the group request |
925 |
|
|
itself. Useful when you queued a lot of events but got a result early. |
926 |
|
|
|
927 |
root |
1.58 |
=item $grp->result (...) |
928 |
|
|
|
929 |
|
|
Set the result value(s) that will be passed to the group callback when all |
930 |
root |
1.80 |
subrequests have finished and set thre groups errno to the current value |
931 |
|
|
of errno (just like calling C<errno> without an error number). By default, |
932 |
|
|
no argument will be passed and errno is zero. |
933 |
|
|
|
934 |
|
|
=item $grp->errno ([$errno]) |
935 |
|
|
|
936 |
|
|
Sets the group errno value to C<$errno>, or the current value of errno |
937 |
|
|
when the argument is missing. |
938 |
|
|
|
939 |
|
|
Every aio request has an associated errno value that is restored when |
940 |
|
|
the callback is invoked. This method lets you change this value from its |
941 |
|
|
default (0). |
942 |
|
|
|
943 |
|
|
Calling C<result> will also set errno, so make sure you either set C<$!> |
944 |
|
|
before the call to C<result>, or call c<errno> after it. |
945 |
root |
1.58 |
|
946 |
root |
1.65 |
=item feed $grp $callback->($grp) |
947 |
root |
1.60 |
|
948 |
|
|
Sets a feeder/generator on this group: every group can have an attached |
949 |
|
|
generator that generates requests if idle. The idea behind this is that, |
950 |
|
|
although you could just queue as many requests as you want in a group, |
951 |
|
|
this might starve other requests for a potentially long time. For |
952 |
|
|
example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> |
953 |
|
|
requests, delaying any later requests for a long time. |
954 |
|
|
|
955 |
|
|
To avoid this, and allow incremental generation of requests, you can |
956 |
|
|
instead a group and set a feeder on it that generates those requests. The |
957 |
root |
1.68 |
feed callback will be called whenever there are few enough (see C<limit>, |
958 |
root |
1.60 |
below) requests active in the group itself and is expected to queue more |
959 |
|
|
requests. |
960 |
|
|
|
961 |
root |
1.68 |
The feed callback can queue as many requests as it likes (i.e. C<add> does |
962 |
|
|
not impose any limits). |
963 |
root |
1.60 |
|
964 |
root |
1.65 |
If the feed does not queue more requests when called, it will be |
965 |
root |
1.60 |
automatically removed from the group. |
966 |
|
|
|
967 |
root |
1.65 |
If the feed limit is C<0>, it will be set to C<2> automatically. |
968 |
root |
1.60 |
|
969 |
|
|
Example: |
970 |
|
|
|
971 |
|
|
# stat all files in @files, but only ever use four aio requests concurrently: |
972 |
|
|
|
973 |
|
|
my $grp = aio_group sub { print "finished\n" }; |
974 |
root |
1.68 |
limit $grp 4; |
975 |
root |
1.65 |
feed $grp sub { |
976 |
root |
1.60 |
my $file = pop @files |
977 |
|
|
or return; |
978 |
|
|
|
979 |
|
|
add $grp aio_stat $file, sub { ... }; |
980 |
root |
1.65 |
}; |
981 |
root |
1.60 |
|
982 |
root |
1.68 |
=item limit $grp $num |
983 |
root |
1.60 |
|
984 |
|
|
Sets the feeder limit for the group: The feeder will be called whenever |
985 |
|
|
the group contains less than this many requests. |
986 |
|
|
|
987 |
|
|
Setting the limit to C<0> will pause the feeding process. |
988 |
|
|
|
989 |
root |
1.55 |
=back |
990 |
|
|
|
991 |
root |
1.5 |
=head2 SUPPORT FUNCTIONS |
992 |
|
|
|
993 |
root |
1.86 |
=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
994 |
|
|
|
995 |
root |
1.5 |
=over 4 |
996 |
|
|
|
997 |
|
|
=item $fileno = IO::AIO::poll_fileno |
998 |
|
|
|
999 |
root |
1.20 |
Return the I<request result pipe file descriptor>. This filehandle must be |
1000 |
|
|
polled for reading by some mechanism outside this module (e.g. Event or |
1001 |
|
|
select, see below or the SYNOPSIS). If the pipe becomes readable you have |
1002 |
|
|
to call C<poll_cb> to check the results. |
1003 |
root |
1.5 |
|
1004 |
|
|
See C<poll_cb> for an example. |
1005 |
|
|
|
1006 |
|
|
=item IO::AIO::poll_cb |
1007 |
|
|
|
1008 |
root |
1.86 |
Process some outstanding events on the result pipe. You have to call this |
1009 |
root |
1.5 |
regularly. Returns the number of events processed. Returns immediately |
1010 |
root |
1.86 |
when no events are outstanding. The amount of events processed depends on |
1011 |
|
|
the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>. |
1012 |
root |
1.5 |
|
1013 |
root |
1.78 |
If not all requests were processed for whatever reason, the filehandle |
1014 |
|
|
will still be ready when C<poll_cb> returns. |
1015 |
|
|
|
1016 |
root |
1.20 |
Example: Install an Event watcher that automatically calls |
1017 |
|
|
IO::AIO::poll_cb with high priority: |
1018 |
root |
1.5 |
|
1019 |
|
|
Event->io (fd => IO::AIO::poll_fileno, |
1020 |
|
|
poll => 'r', async => 1, |
1021 |
|
|
cb => \&IO::AIO::poll_cb); |
1022 |
|
|
|
1023 |
root |
1.86 |
=item IO::AIO::max_poll_reqs $nreqs |
1024 |
|
|
|
1025 |
|
|
=item IO::AIO::max_poll_time $seconds |
1026 |
|
|
|
1027 |
|
|
These set the maximum number of requests (default C<0>, meaning infinity) |
1028 |
|
|
that are being processed by C<IO::AIO::poll_cb> in one call, respectively |
1029 |
|
|
the maximum amount of time (default C<0>, meaning infinity) spent in |
1030 |
|
|
C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount |
1031 |
|
|
of time C<poll_cb> is allowed to use). |
1032 |
root |
1.78 |
|
1033 |
root |
1.89 |
Setting C<max_poll_time> to a non-zero value creates an overhead of one |
1034 |
|
|
syscall per request processed, which is not normally a problem unless your |
1035 |
|
|
callbacks are really really fast or your OS is really really slow (I am |
1036 |
|
|
not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead. |
1037 |
|
|
|
1038 |
root |
1.86 |
Setting these is useful if you want to ensure some level of |
1039 |
|
|
interactiveness when perl is not fast enough to process all requests in |
1040 |
|
|
time. |
1041 |
root |
1.78 |
|
1042 |
root |
1.86 |
For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
1043 |
root |
1.78 |
|
1044 |
|
|
Example: Install an Event watcher that automatically calls |
1045 |
root |
1.89 |
IO::AIO::poll_cb with low priority, to ensure that other parts of the |
1046 |
root |
1.78 |
program get the CPU sometimes even under high AIO load. |
1047 |
|
|
|
1048 |
root |
1.86 |
# try not to spend much more than 0.1s in poll_cb |
1049 |
|
|
IO::AIO::max_poll_time 0.1; |
1050 |
|
|
|
1051 |
|
|
# use a low priority so other tasks have priority |
1052 |
root |
1.78 |
Event->io (fd => IO::AIO::poll_fileno, |
1053 |
|
|
poll => 'r', nice => 1, |
1054 |
root |
1.86 |
cb => &IO::AIO::poll_cb); |
1055 |
root |
1.78 |
|
1056 |
root |
1.5 |
=item IO::AIO::poll_wait |
1057 |
|
|
|
1058 |
root |
1.93 |
If there are any outstanding requests and none of them in the result |
1059 |
|
|
phase, wait till the result filehandle becomes ready for reading (simply |
1060 |
|
|
does a C<select> on the filehandle. This is useful if you want to |
1061 |
|
|
synchronously wait for some requests to finish). |
1062 |
root |
1.5 |
|
1063 |
|
|
See C<nreqs> for an example. |
1064 |
|
|
|
1065 |
root |
1.86 |
=item IO::AIO::poll |
1066 |
root |
1.5 |
|
1067 |
root |
1.86 |
Waits until some requests have been handled. |
1068 |
root |
1.5 |
|
1069 |
root |
1.92 |
Returns the number of requests processed, but is otherwise strictly |
1070 |
|
|
equivalent to: |
1071 |
root |
1.5 |
|
1072 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
1073 |
root |
1.80 |
|
1074 |
root |
1.12 |
=item IO::AIO::flush |
1075 |
|
|
|
1076 |
|
|
Wait till all outstanding AIO requests have been handled. |
1077 |
|
|
|
1078 |
root |
1.13 |
Strictly equivalent to: |
1079 |
|
|
|
1080 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
1081 |
|
|
while IO::AIO::nreqs; |
1082 |
|
|
|
1083 |
root |
1.104 |
=back |
1084 |
|
|
|
1085 |
root |
1.86 |
=head3 CONTROLLING THE NUMBER OF THREADS |
1086 |
root |
1.13 |
|
1087 |
root |
1.105 |
=over |
1088 |
|
|
|
1089 |
root |
1.5 |
=item IO::AIO::min_parallel $nthreads |
1090 |
|
|
|
1091 |
root |
1.61 |
Set the minimum number of AIO threads to C<$nthreads>. The current |
1092 |
|
|
default is C<8>, which means eight asynchronous operations can execute |
1093 |
|
|
concurrently at any one time (the number of outstanding requests, |
1094 |
|
|
however, is unlimited). |
1095 |
root |
1.5 |
|
1096 |
root |
1.34 |
IO::AIO starts threads only on demand, when an AIO request is queued and |
1097 |
root |
1.86 |
no free thread exists. Please note that queueing up a hundred requests can |
1098 |
|
|
create demand for a hundred threads, even if it turns out that everything |
1099 |
|
|
is in the cache and could have been processed faster by a single thread. |
1100 |
root |
1.34 |
|
1101 |
root |
1.61 |
It is recommended to keep the number of threads relatively low, as some |
1102 |
|
|
Linux kernel versions will scale negatively with the number of threads |
1103 |
|
|
(higher parallelity => MUCH higher latency). With current Linux 2.6 |
1104 |
|
|
versions, 4-32 threads should be fine. |
1105 |
root |
1.5 |
|
1106 |
root |
1.34 |
Under most circumstances you don't need to call this function, as the |
1107 |
|
|
module selects a default that is suitable for low to moderate load. |
1108 |
root |
1.5 |
|
1109 |
|
|
=item IO::AIO::max_parallel $nthreads |
1110 |
|
|
|
1111 |
root |
1.34 |
Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
1112 |
|
|
specified number of threads are currently running, this function kills |
1113 |
|
|
them. This function blocks until the limit is reached. |
1114 |
|
|
|
1115 |
|
|
While C<$nthreads> are zero, aio requests get queued but not executed |
1116 |
|
|
until the number of threads has been increased again. |
1117 |
root |
1.5 |
|
1118 |
|
|
This module automatically runs C<max_parallel 0> at program end, to ensure |
1119 |
|
|
that all threads are killed and that there are no outstanding requests. |
1120 |
|
|
|
1121 |
|
|
Under normal circumstances you don't need to call this function. |
1122 |
|
|
|
1123 |
root |
1.86 |
=item IO::AIO::max_idle $nthreads |
1124 |
|
|
|
1125 |
|
|
Limit the number of threads (default: 4) that are allowed to idle (i.e., |
1126 |
|
|
threads that did not get a request to process within 10 seconds). That |
1127 |
|
|
means if a thread becomes idle while C<$nthreads> other threads are also |
1128 |
|
|
idle, it will free its resources and exit. |
1129 |
|
|
|
1130 |
|
|
This is useful when you allow a large number of threads (e.g. 100 or 1000) |
1131 |
|
|
to allow for extremely high load situations, but want to free resources |
1132 |
|
|
under normal circumstances (1000 threads can easily consume 30MB of RAM). |
1133 |
|
|
|
1134 |
|
|
The default is probably ok in most situations, especially if thread |
1135 |
|
|
creation is fast. If thread creation is very slow on your system you might |
1136 |
|
|
want to use larger values. |
1137 |
|
|
|
1138 |
root |
1.79 |
=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
1139 |
root |
1.5 |
|
1140 |
root |
1.79 |
This is a very bad function to use in interactive programs because it |
1141 |
|
|
blocks, and a bad way to reduce concurrency because it is inexact: Better |
1142 |
|
|
use an C<aio_group> together with a feed callback. |
1143 |
|
|
|
1144 |
|
|
Sets the maximum number of outstanding requests to C<$nreqs>. If you |
1145 |
|
|
to queue up more than this number of requests, the next call to the |
1146 |
|
|
C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>) |
1147 |
|
|
function will block until the limit is no longer exceeded. |
1148 |
|
|
|
1149 |
|
|
The default value is very large, so there is no practical limit on the |
1150 |
|
|
number of outstanding requests. |
1151 |
|
|
|
1152 |
|
|
You can still queue as many requests as you want. Therefore, |
1153 |
|
|
C<max_oustsanding> is mainly useful in simple scripts (with low values) or |
1154 |
|
|
as a stop gap to shield against fatal memory overflow (with large values). |
1155 |
root |
1.5 |
|
1156 |
root |
1.104 |
=back |
1157 |
|
|
|
1158 |
root |
1.86 |
=head3 STATISTICAL INFORMATION |
1159 |
|
|
|
1160 |
root |
1.104 |
=over |
1161 |
|
|
|
1162 |
root |
1.86 |
=item IO::AIO::nreqs |
1163 |
|
|
|
1164 |
|
|
Returns the number of requests currently in the ready, execute or pending |
1165 |
|
|
states (i.e. for which their callback has not been invoked yet). |
1166 |
|
|
|
1167 |
|
|
Example: wait till there are no outstanding requests anymore: |
1168 |
|
|
|
1169 |
|
|
IO::AIO::poll_wait, IO::AIO::poll_cb |
1170 |
|
|
while IO::AIO::nreqs; |
1171 |
|
|
|
1172 |
|
|
=item IO::AIO::nready |
1173 |
|
|
|
1174 |
|
|
Returns the number of requests currently in the ready state (not yet |
1175 |
|
|
executed). |
1176 |
|
|
|
1177 |
|
|
=item IO::AIO::npending |
1178 |
|
|
|
1179 |
|
|
Returns the number of requests currently in the pending state (executed, |
1180 |
|
|
but not yet processed by poll_cb). |
1181 |
|
|
|
1182 |
root |
1.5 |
=back |
1183 |
|
|
|
1184 |
root |
1.1 |
=cut |
1185 |
|
|
|
1186 |
root |
1.2 |
# support function to convert a fd into a perl filehandle |
1187 |
|
|
sub _fd2fh { |
1188 |
|
|
return undef if $_[0] < 0; |
1189 |
|
|
|
1190 |
root |
1.23 |
# try to generate nice filehandles |
1191 |
|
|
my $sym = "IO::AIO::fd#$_[0]"; |
1192 |
|
|
local *$sym; |
1193 |
root |
1.25 |
|
1194 |
root |
1.27 |
open *$sym, "+<&=$_[0]" # usually works under any unix |
1195 |
|
|
or open *$sym, "<&=$_[0]" # cygwin needs this |
1196 |
|
|
or open *$sym, ">&=$_[0]" # or this |
1197 |
root |
1.2 |
or return undef; |
1198 |
|
|
|
1199 |
root |
1.23 |
*$sym |
1200 |
root |
1.2 |
} |
1201 |
|
|
|
1202 |
root |
1.61 |
min_parallel 8; |
1203 |
root |
1.1 |
|
1204 |
root |
1.95 |
END { flush } |
1205 |
root |
1.82 |
|
1206 |
root |
1.1 |
1; |
1207 |
|
|
|
1208 |
root |
1.27 |
=head2 FORK BEHAVIOUR |
1209 |
|
|
|
1210 |
root |
1.52 |
This module should do "the right thing" when the process using it forks: |
1211 |
|
|
|
1212 |
root |
1.34 |
Before the fork, IO::AIO enters a quiescent state where no requests |
1213 |
|
|
can be added in other threads and no results will be processed. After |
1214 |
|
|
the fork the parent simply leaves the quiescent state and continues |
1215 |
root |
1.72 |
request/result processing, while the child frees the request/result queue |
1216 |
|
|
(so that the requests started before the fork will only be handled in the |
1217 |
|
|
parent). Threads will be started on demand until the limit set in the |
1218 |
root |
1.34 |
parent process has been reached again. |
1219 |
root |
1.27 |
|
1220 |
root |
1.52 |
In short: the parent will, after a short pause, continue as if fork had |
1221 |
|
|
not been called, while the child will act as if IO::AIO has not been used |
1222 |
|
|
yet. |
1223 |
|
|
|
1224 |
root |
1.60 |
=head2 MEMORY USAGE |
1225 |
|
|
|
1226 |
root |
1.72 |
Per-request usage: |
1227 |
|
|
|
1228 |
|
|
Each aio request uses - depending on your architecture - around 100-200 |
1229 |
|
|
bytes of memory. In addition, stat requests need a stat buffer (possibly |
1230 |
|
|
a few hundred bytes), readdir requires a result buffer and so on. Perl |
1231 |
|
|
scalars and other data passed into aio requests will also be locked and |
1232 |
|
|
will consume memory till the request has entered the done state. |
1233 |
root |
1.60 |
|
1234 |
|
|
This is now awfully much, so queuing lots of requests is not usually a |
1235 |
|
|
problem. |
1236 |
|
|
|
1237 |
root |
1.72 |
Per-thread usage: |
1238 |
|
|
|
1239 |
|
|
In the execution phase, some aio requests require more memory for |
1240 |
|
|
temporary buffers, and each thread requires a stack and other data |
1241 |
|
|
structures (usually around 16k-128k, depending on the OS). |
1242 |
|
|
|
1243 |
|
|
=head1 KNOWN BUGS |
1244 |
|
|
|
1245 |
root |
1.73 |
Known bugs will be fixed in the next release. |
1246 |
root |
1.60 |
|
1247 |
root |
1.1 |
=head1 SEE ALSO |
1248 |
|
|
|
1249 |
root |
1.68 |
L<Coro::AIO>. |
1250 |
root |
1.1 |
|
1251 |
|
|
=head1 AUTHOR |
1252 |
|
|
|
1253 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
1254 |
|
|
http://home.schmorp.de/ |
1255 |
|
|
|
1256 |
|
|
=cut |
1257 |
|
|
|