--- IO-AIO/AIO.pm 2007/08/13 12:08:13 1.111 +++ IO-AIO/AIO.pm 2009/08/18 03:26:02 1.164 @@ -28,9 +28,11 @@ my $grp = aio_group sub { print "all stats done\n" }; add $grp aio_stat "..." for ...; - # AnyEvent integration - open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; - my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); + # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) + use AnyEvent::AIO; + + # EV integration + my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; # Event integration Event->io (fd => IO::AIO::poll_fileno, @@ -52,7 +54,8 @@ =head1 DESCRIPTION This module implements asynchronous I/O using whatever means your -operating system supports. +operating system supports. It is implemented as an interface to C +(L). Asynchronous means that operations that can normally block your program (e.g. reading from disk) will be done asynchronously: the operation @@ -66,8 +69,8 @@ While most of this works on all types of file descriptors (for example sockets), using these functions on file descriptors that -support nonblocking operation (again, sockets, pipes etc.) is very -inefficient. Use an event loop for that (such as the L +support nonblocking operation (again, sockets, pipes etc.) is +very inefficient. Use an event loop for that (such as the L module): IO::AIO will naturally fit into such an event loop itself. In this version, a number of threads are started that execute your @@ -87,17 +90,15 @@ =head2 EXAMPLE -This is a simple example that uses the Event module and loads +This is a simple example that uses the EV module and loads F asynchronously: use Fcntl; - use Event; + use EV; use IO::AIO; - # register the IO::AIO callback with Event - Event->io (fd => IO::AIO::poll_fileno, - poll => 'r', - cb => \&IO::AIO::poll_cb); + # register the IO::AIO callback with EV + my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; # queue the request to open /etc/passwd aio_open "/etc/passwd", O_RDONLY, 0, sub { @@ -119,7 +120,7 @@ print $contents; # exit event loop and program - Event::unloop; + EV::unloop; }; }; @@ -127,7 +128,7 @@ # check for sockets etc. etc. # process events as long as there are some: - Event::loop; + EV::loop; =head1 REQUEST ANATOMY AND LIFETIME @@ -185,24 +186,31 @@ package IO::AIO; -no warnings; -use strict 'vars'; +use Carp (); + +use common::sense; use base 'Exporter'; BEGIN { - our $VERSION = '2.4'; + our $VERSION = '3.3'; - our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat - aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink - aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link - aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir - aio_chown aio_chmod aio_utime aio_truncate); - our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block)); + our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close + aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx + aio_scandir aio_symlink aio_readlink aio_sync aio_fsync + aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead + aio_rename aio_link aio_move aio_copy aio_group + aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown + aio_chmod aio_utime aio_truncate); + + our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush min_parallel max_parallel max_idle nreqs nready npending nthreads - max_poll_time max_poll_reqs); + max_poll_time max_poll_reqs + sendfile fadvise); + + push @AIO_REQ, qw(aio_busy); # not exported @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; @@ -219,7 +227,7 @@ and they all accept an additional (and optional) C<$callback> argument which must be a code reference. This code reference will get called with the syscall return code (e.g. most syscalls return C<-1> on error, unlike -perl, which usually delivers "false") as it's sole argument when the given +perl, which usually delivers "false") as its sole argument after the given syscall has been executed asynchronously. All functions expecting a filehandle keep a copy of the filehandle @@ -243,7 +251,7 @@ use something else to ensure your scalar has the correct contents. This works, btw. independent of the internal UTF-8 bit, which IO::AIO -handles correctly wether it is set or not. +handles correctly whether it is set or not. =over 4 @@ -313,28 +321,38 @@ =item aio_close $fh, $callback->($status) Asynchronously close a file and call the callback with the result -code. I although accepted, you should not pass in a perl -filehandle here, as perl will likely close the file descriptor another -time when the filehandle is destroyed. Normally, you can safely call perls -C or just let filehandles go out of scope. +code. + +Unfortunately, you can't do this to perl. Perl I very strongly on +closing the file descriptor associated with the filehandle itself. -This is supposed to be a bug in the API, so that might change. It's -therefore best to avoid this function. +Therefore, C will not close the filehandle - instead it will +use dup2 to overwrite the file descriptor with the write-end of a pipe +(the pipe fd will be created on demand and will be cached). +Or in other words: the file descriptor will be closed, but it will not be +free for reuse until the perl filehandle is closed. + +=cut =item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) =item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) -Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset> -into the scalar given by C<$data> and offset C<$dataoffset> and calls the -callback without the actual number of bytes read (or -1 on error, just -like the syscall). +Reads or writes C<$length> bytes from or to the specified C<$fh> and +C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> +and calls the callback without the actual number of bytes read (or -1 on +error, just like the syscall). + +C will, like C, shrink or grow the C<$data> scalar to +offset plus the actual number of bytes read. + +If C<$offset> is undefined, then the current file descriptor offset will +be used (and updated), otherwise the file descriptor offset will not be +changed by these calls. -If C<$offset> is undefined, then the current file offset will be used (and -updated), otherwise the file offset will not be changed by these calls. - -If C<$length> is undefined in C, use the remaining length of C<$data>. +If C<$length> is undefined in C, use the remaining length of +C<$data>. If C<$dataoffset> is less than zero, it will be counted from the end of C<$data>. @@ -516,8 +534,74 @@ directory (i.e. opendir + readdir + closedir). The entries will not be sorted, and will B include the C<.> and C<..> entries. -The callback a single argument which is either C or an array-ref -with the filenames. +The callback is passed a single argument which is either C or an +array-ref with the filenames. + + +=item aio_readdirx $pathname, $flags, $callback->($entries, $flags) + +Quite similar to C, but the C<$flags> argument allows to tune +behaviour and output format. In case of an error, C<$entries> will be +C. + +The flags are a combination of the following constants, ORed together (the +flags will also be passed to the callback, possibly modified): + +=over 4 + +=item IO::AIO::READDIR_DENTS + +When this flag is off, then the callback gets an arrayref with of names +only (as with C), otherwise it gets an arrayref with +C<[$name, $type, $inode]> arrayrefs, each describing a single directory +entry in more detail. + +C<$name> is the name of the entry. + +C<$type> is one of the C constants: + +C, C, C, C, +C, C, C, C, +C. + +C means just that: readdir does not know. If you need to +know, you have to run stat yourself. Also, for speed reasons, the C<$type> +scalars are read-only: you can not modify them. + +C<$inode> is the inode number (which might not be exact on systems with 64 +bit inode numbers and 32 bit perls). This field has unspecified content on +systems that do not deliver the inode information. + +=item IO::AIO::READDIR_DIRS_FIRST + +When this flag is set, then the names will be returned in an order where +likely directories come first. This is useful when you need to quickly +find directories, or you want to find all directories while avoiding to +stat() each entry. + +If the system returns type information in readdir, then this is used +to find directories directly. Otherwise, likely directories are files +beginning with ".", or otherwise files with no dots, of which files with +short names are tried first. + +=item IO::AIO::READDIR_STAT_ORDER + +When this flag is set, then the names will be returned in an order +suitable for stat()'ing each one. That is, when you plan to stat() +all files in the given directory, then the returned order will likely +be fastest. + +If both this flag and C are specified, then +the likely dirs come first, resulting in a less optimal stat order. + +=item IO::AIO::READDIR_FOUND_UNKNOWN + +This flag should not be set when calling C. Instead, it +is being set by C, when any of the C<$type>'s found were +C. The absense of this flag therefore indicates that all +C<$type>'s are known, which can be used to speed up some algorithms. + +=back =item aio_load $path, $data, $callback->($status) @@ -528,35 +612,33 @@ =cut sub aio_load($$;$) { - aio_block { - my ($path, undef, $cb) = @_; - my $data = \$_[1]; + my ($path, undef, $cb) = @_; + my $data = \$_[1]; - my $pri = aioreq_pri; - my $grp = aio_group $cb; + my $pri = aioreq_pri; + my $grp = aio_group $cb; - aioreq_pri $pri; - add $grp aio_open $path, O_RDONLY, 0, sub { - my $fh = shift - or return $grp->result (-1); + aioreq_pri $pri; + add $grp aio_open $path, O_RDONLY, 0, sub { + my $fh = shift + or return $grp->result (-1); - aioreq_pri $pri; - add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { - $grp->result ($_[0]); - }; + aioreq_pri $pri; + add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { + $grp->result ($_[0]); }; + }; - $grp - } + $grp } =item aio_copy $srcpath, $dstpath, $callback->($status) Try to copy the I (directories not supported as either source or destination) from C<$srcpath> to C<$dstpath> and call the callback with -the C<0> (error) or C<-1> ok. +a status of C<0> (error) or C<-1> (ok). -This is a composite request that it creates the destination file with +This is a composite request that creates the destination file with mode 0200 and copies the contents of the source file into it using C, followed by restoring atime, mtime, access mode and uid/gid, in that order. @@ -568,92 +650,103 @@ =cut sub aio_copy($$;$) { - aio_block { - my ($src, $dst, $cb) = @_; + my ($src, $dst, $cb) = @_; - my $pri = aioreq_pri; - my $grp = aio_group $cb; + my $pri = aioreq_pri; + my $grp = aio_group $cb; - aioreq_pri $pri; - add $grp aio_open $src, O_RDONLY, 0, sub { - if (my $src_fh = $_[0]) { - my @stat = stat $src_fh; + aioreq_pri $pri; + add $grp aio_open $src, O_RDONLY, 0, sub { + if (my $src_fh = $_[0]) { + my @stat = stat $src_fh; # hmm, might bock over nfs? - aioreq_pri $pri; - add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { - if (my $dst_fh = $_[0]) { - aioreq_pri $pri; - add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { - if ($_[0] == $stat[7]) { - $grp->result (0); - close $src_fh; - - # those should not normally block. should. should. - utime $stat[8], $stat[9], $dst; - chmod $stat[2] & 07777, $dst_fh; - chown $stat[4], $stat[5], $dst_fh; - close $dst_fh; - } else { - $grp->result (-1); - close $src_fh; - close $dst_fh; + aioreq_pri $pri; + add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { + if (my $dst_fh = $_[0]) { + aioreq_pri $pri; + add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { + if ($_[0] == $stat[7]) { + $grp->result (0); + close $src_fh; - aioreq $pri; - add $grp aio_unlink $dst; - } - }; - } else { - $grp->result (-1); - } - }, - - } else { - $grp->result (-1); - } - }; + my $ch = sub { + aioreq_pri $pri; + add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub { + aioreq_pri $pri; + add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub { + aioreq_pri $pri; + add $grp aio_close $dst_fh; + } + }; + }; + + aioreq_pri $pri; + add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub { + if ($_[0] < 0 && $! == ENOSYS) { + aioreq_pri $pri; + add $grp aio_utime $dst, $stat[8], $stat[9], $ch; + } else { + $ch->(); + } + }; + } else { + $grp->result (-1); + close $src_fh; + close $dst_fh; + + aioreq $pri; + add $grp aio_unlink $dst; + } + }; + } else { + $grp->result (-1); + } + }, - $grp - } + } else { + $grp->result (-1); + } + }; + + $grp } =item aio_move $srcpath, $dstpath, $callback->($status) Try to move the I (directories not supported as either source or destination) from C<$srcpath> to C<$dstpath> and call the callback with -the C<0> (error) or C<-1> ok. +the status C<0> (error) or C<-1> (ok). -This is a composite request that tries to rename(2) the file first. If -rename files with C, it copies the file with C and, if -that is successful, unlinking the C<$srcpath>. +This is a composite request that tries to rename(2) the file first; if +rename fails with C, it copies the file with C and, if +that is successful, unlinks the C<$srcpath>. =cut sub aio_move($$;$) { - aio_block { - my ($src, $dst, $cb) = @_; + my ($src, $dst, $cb) = @_; - my $pri = aioreq_pri; - my $grp = aio_group $cb; - - aioreq_pri $pri; - add $grp aio_rename $src, $dst, sub { - if ($_[0] && $! == EXDEV) { - aioreq_pri $pri; - add $grp aio_copy $src, $dst, sub { - $grp->result ($_[0]); + my $pri = aioreq_pri; + my $grp = aio_group $cb; - if (!$_[0]) { - aioreq_pri $pri; - add $grp aio_unlink $src; - } - }; - } else { + aioreq_pri $pri; + add $grp aio_rename $src, $dst, sub { + if ($_[0] && $! == EXDEV) { + aioreq_pri $pri; + add $grp aio_copy $src, $dst, sub { $grp->result ($_[0]); - } - }; - $grp - } + if (!$_[0]) { + aioreq_pri $pri; + add $grp aio_unlink $src; + } + }; + } else { + $grp->result ($_[0]); + } + }; + + $grp } =item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) @@ -683,20 +776,24 @@ The C cannot be avoided, but C'ing every entry can. -After reading the directory, the modification time, size etc. of the -directory before and after the readdir is checked, and if they match (and -isn't the current time), the link count will be used to decide how many -entries are directories (if >= 2). Otherwise, no knowledge of the number -of subdirectories will be assumed. - -Then entries will be sorted into likely directories (everything without -a non-initial dot currently) and likely non-directories (everything -else). Then every entry plus an appended C will be C'ed, -likely directories first. If that succeeds, it assumes that the entry -is a directory or a symlink to directory (which will be checked +If readdir returns file type information, then this is used directly to +find directories. + +Otherwise, after reading the directory, the modification time, size etc. +of the directory before and after the readdir is checked, and if they +match (and isn't the current time), the link count will be used to decide +how many entries are directories (if >= 2). Otherwise, no knowledge of the +number of subdirectories will be assumed. + +Then entries will be sorted into likely directories a non-initial dot +currently) and likely non-directories (see C). Then every +entry plus an appended C will be C'ed, likely directories first, +in order of their inode numbers. If that succeeds, it assumes that the +entry is a directory or a symlink to directory (which will be checked seperately). This is often faster than stat'ing the entry itself because filesystems might detect the type of the entry without reading the inode -data (e.g. ext2fs filetype feature). +data (e.g. ext2fs filetype feature), even on systems that cannot return +the filetype information on readdir. If the known number of directories (link count - 2) has been reached, the rest of the entries is assumed to be non-directories. @@ -711,91 +808,82 @@ =cut sub aio_scandir($$;$) { - aio_block { - my ($path, $maxreq, $cb) = @_; + my ($path, $maxreq, $cb) = @_; + + my $pri = aioreq_pri; - my $pri = aioreq_pri; + my $grp = aio_group $cb; - my $grp = aio_group $cb; + $maxreq = 4 if $maxreq <= 0; - $maxreq = 4 if $maxreq <= 0; + # stat once + aioreq_pri $pri; + add $grp aio_stat $path, sub { + return $grp->result () if $_[0]; + my $now = time; + my $hash1 = join ":", (stat _)[0,1,3,7,9]; - # stat once + # read the directory entries aioreq_pri $pri; - add $grp aio_stat $path, sub { - return $grp->result () if $_[0]; - my $now = time; - my $hash1 = join ":", (stat _)[0,1,3,7,9]; + add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub { + my $entries = shift + or return $grp->result (); - # read the directory entries + # stat the dir another time aioreq_pri $pri; - add $grp aio_readdir $path, sub { - my $entries = shift - or return $grp->result (); - - # stat the dir another time - aioreq_pri $pri; - add $grp aio_stat $path, sub { - my $hash2 = join ":", (stat _)[0,1,3,7,9]; + add $grp aio_stat $path, sub { + my $hash2 = join ":", (stat _)[0,1,3,7,9]; - my $ndirs; + my $ndirs; - # take the slow route if anything looks fishy - if ($hash1 ne $hash2 or (stat _)[9] == $now) { - $ndirs = -1; - } else { - # if nlink == 2, we are finished - # on non-posix-fs's, we rely on nlink < 2 - $ndirs = (stat _)[3] - 2 - or return $grp->result ([], $entries); - } - - # sort into likely dirs and likely nondirs - # dirs == files without ".", short entries first - $entries = [map $_->[0], - sort { $b->[1] cmp $a->[1] } - map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], - @$entries]; + # take the slow route if anything looks fishy + if ($hash1 ne $hash2 or (stat _)[9] == $now) { + $ndirs = -1; + } else { + # if nlink == 2, we are finished + # for non-posix-fs's, we rely on nlink < 2 + $ndirs = (stat _)[3] - 2 + or return $grp->result ([], $entries); + } - my (@dirs, @nondirs); + my (@dirs, @nondirs); - my $statgrp = add $grp aio_group sub { - $grp->result (\@dirs, \@nondirs); - }; + my $statgrp = add $grp aio_group sub { + $grp->result (\@dirs, \@nondirs); + }; - limit $statgrp $maxreq; - feed $statgrp sub { - return unless @$entries; - my $entry = pop @$entries; - - aioreq_pri $pri; - add $statgrp aio_stat "$path/$entry/.", sub { - if ($_[0] < 0) { - push @nondirs, $entry; - } else { - # need to check for real directory - aioreq_pri $pri; - add $statgrp aio_lstat "$path/$entry", sub { - if (-d _) { - push @dirs, $entry; - - unless (--$ndirs) { - push @nondirs, @$entries; - feed $statgrp; - } - } else { - push @nondirs, $entry; + limit $statgrp $maxreq; + feed $statgrp sub { + return unless @$entries; + my $entry = shift @$entries; + + aioreq_pri $pri; + add $statgrp aio_stat "$path/$entry/.", sub { + if ($_[0] < 0) { + push @nondirs, $entry; + } else { + # need to check for real directory + aioreq_pri $pri; + add $statgrp aio_lstat "$path/$entry", sub { + if (-d _) { + push @dirs, $entry; + + unless (--$ndirs) { + push @nondirs, @$entries; + feed $statgrp; } + } else { + push @nondirs, $entry; } } - }; + } }; }; }; }; + }; - $grp - } + $grp } =item aio_rmtree $path, $callback->($status) @@ -809,32 +897,34 @@ sub aio_rmtree; sub aio_rmtree($;$) { - aio_block { - my ($path, $cb) = @_; + my ($path, $cb) = @_; - my $pri = aioreq_pri; - my $grp = aio_group $cb; + my $pri = aioreq_pri; + my $grp = aio_group $cb; - aioreq_pri $pri; - add $grp aio_scandir $path, 0, sub { - my ($dirs, $nondirs) = @_; + aioreq_pri $pri; + add $grp aio_scandir $path, 0, sub { + my ($dirs, $nondirs) = @_; - my $dirgrp = aio_group sub { - add $grp aio_rmdir $path, sub { - $grp->result ($_[0]); - }; + my $dirgrp = aio_group sub { + add $grp aio_rmdir $path, sub { + $grp->result ($_[0]); }; + }; - (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; - (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; + (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; + (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; - add $grp $dirgrp; - }; + add $grp $dirgrp; + }; - $grp - } + $grp } +=item aio_sync $callback->($status) + +Asynchronously call sync and call the callback when finished. + =item aio_fsync $fh, $callback->($status) Asynchronously call fsync on the given filehandle and call the callback @@ -848,6 +938,59 @@ If this call isn't available because your OS lacks it or it couldn't be detected, it will be emulated by calling C instead. +=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) + +Sync the data portion of the file specified by C<$offset> and C<$length> +to disk (but NOT the metadata), by calling the Linux-specific +sync_file_range call. If sync_file_range is not available or it returns +ENOSYS, then fdatasync or fsync is being substituted. + +C<$flags> can be a combination of C, +C and +C: refer to the sync_file_range +manpage for details. + +=item aio_pathsync $path, $callback->($status) + +This request tries to open, fsync and close the given path. This is a +composite request intended to sync directories after directory operations +(E.g. rename). This might not work on all operating systems or have any +specific effect, but usually it makes sure that directory changes get +written to disc. It works for anything that can be opened for read-only, +not just directories. + +Future versions of this function might fall back to other methods when +C on the directory fails (such as calling C). + +Passes C<0> when everything went ok, and C<-1> on error. + +=cut + +sub aio_pathsync($;$) { + my ($path, $cb) = @_; + + my $pri = aioreq_pri; + my $grp = aio_group $cb; + + aioreq_pri $pri; + add $grp aio_open $path, O_RDONLY, 0, sub { + my ($fh) = @_; + if ($fh) { + aioreq_pri $pri; + add $grp aio_fsync $fh, sub { + $grp->result ($_[0]); + + aioreq_pri $pri; + add $grp aio_close $fh; + }; + } else { + $grp->result (-1); + } + }; + + $grp +} + =item aio_group $callback->(...) This is a very special aio request: Instead of doing something, it is a @@ -906,8 +1049,9 @@ Cancels the request, if possible. Has the effect of skipping execution when entering the B state and skipping calling the callback when entering the the B state, but will leave the request otherwise -untouched. That means that requests that currently execute will not be -stopped and resources held by the request will not be freed prematurely. +untouched (with the exception of readdir). That means that requests that +currently execute will not be stopped and resources held by the request +will not be freed prematurely. =item cb $req $callback->(...) @@ -968,10 +1112,11 @@ C state, they will also finish. Otherwise they will continue to exist. -That means after creating a group you have some time to add requests. And -in the callbacks of those requests, you can add further requests to the -group. And only when all those requests have finished will the the group -itself finish. +That means after creating a group you have some time to add requests +(precisely before the callback has been invoked, which is only done within +the C). And in the callbacks of those requests, you can add +further requests to the group. And only when all those requests have +finished will the the group itself finish. =over 4 @@ -993,7 +1138,7 @@ =item $grp->result (...) Set the result value(s) that will be passed to the group callback when all -subrequests have finished and set thre groups errno to the current value +subrequests have finished and set the groups errno to the current value of errno (just like calling C without an error number). By default, no argument will be passed and errno is zero. @@ -1014,9 +1159,9 @@ Sets a feeder/generator on this group: every group can have an attached generator that generates requests if idle. The idea behind this is that, although you could just queue as many requests as you want in a group, -this might starve other requests for a potentially long time. For -example, C might generate hundreds of thousands C -requests, delaying any later requests for a long time. +this might starve other requests for a potentially long time. For example, +C might generate hundreds of thousands C requests, +delaying any later requests for a long time. To avoid this, and allow incremental generation of requests, you can instead a group and set a feeder on it that generates those requests. The @@ -1030,7 +1175,8 @@ If the feed does not queue more requests when called, it will be automatically removed from the group. -If the feed limit is C<0>, it will be set to C<2> automatically. +If the feed limit is C<0> when this method is called, it will be set to +C<2> automatically. Example: @@ -1052,6 +1198,9 @@ Setting the limit to C<0> will pause the feeding process. +The default value for the limit is C<0>, but note that setting a feeder +automatically bumps it up to C<2>. + =back =head2 SUPPORT FUNCTIONS @@ -1063,24 +1212,27 @@ =item $fileno = IO::AIO::poll_fileno Return the I. This filehandle must be -polled for reading by some mechanism outside this module (e.g. Event or -select, see below or the SYNOPSIS). If the pipe becomes readable you have -to call C to check the results. +polled for reading by some mechanism outside this module (e.g. EV, Glib, +select and so on, see below or the SYNOPSIS). If the pipe becomes readable +you have to call C to check the results. See C for an example. =item IO::AIO::poll_cb Process some outstanding events on the result pipe. You have to call this -regularly. Returns the number of events processed. Returns immediately -when no events are outstanding. The amount of events processed depends on -the settings of C and C. +regularly. Returns C<0> if all events could be processed, or C<-1> if it +returned earlier for whatever reason. Returns immediately when no events +are outstanding. The amount of events processed depends on the settings of +C and C. If not all requests were processed for whatever reason, the filehandle -will still be ready when C returns. +will still be ready when C returns, so normally you don't have to +do anything special to have it called later. Example: Install an Event watcher that automatically calls -IO::AIO::poll_cb with high priority: +IO::AIO::poll_cb with high priority (more examples can be found in the +SYNOPSIS section, at the top of this document): Event->io (fd => IO::AIO::poll_fileno, poll => 'r', async => 1, @@ -1201,14 +1353,14 @@ creation is fast. If thread creation is very slow on your system you might want to use larger values. -=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs +=item IO::AIO::max_outstanding $maxreqs This is a very bad function to use in interactive programs because it blocks, and a bad way to reduce concurrency because it is inexact: Better use an C together with a feed callback. Sets the maximum number of outstanding requests to C<$nreqs>. If you -to queue up more than this number of requests, the next call to the +do queue up more than this number of requests, the next call to the C (and C and other functions calling C) function will block until the limit is no longer exceeded. @@ -1216,7 +1368,7 @@ number of outstanding requests. You can still queue as many requests as you want. Therefore, -C is mainly useful in simple scripts (with low values) or +C is mainly useful in simple scripts (with low values) or as a stop gap to shield against fatal memory overflow (with large values). =back @@ -1247,23 +1399,36 @@ =back -=cut +=head3 MISCELLANEOUS FUNCTIONS -# support function to convert a fd into a perl filehandle -sub _fd2fh { - return undef if $_[0] < 0; - - # try to generate nice filehandles - my $sym = "IO::AIO::fd#$_[0]"; - local *$sym; - - open *$sym, "+<&=$_[0]" # usually works under any unix - or open *$sym, "<&=$_[0]" # cygwin needs this - or open *$sym, ">&=$_[0]" # or this - or return undef; +IO::AIO implements some functions that might be useful, but are not +asynchronous. - *$sym -} +=over 4 + +=item IO::AIO::sendfile $ofh, $ifh, $offset, $count + +Calls the C function, which is like C, +but is blocking (this makes most sense if you know the input data is +likely cached already and the output filehandle is set to non-blocking +operations). + +Returns the number of bytes copied, or C<-1> on error. + +=item IO::AIO::fadvise $fh, $offset, $len, $advice + +Simply calls the C function (see it's +manpage for details). The following advice constants are +avaiable: C, C, +C, C, +C, C. + +On systems that do not implement C, this function returns +ENOSYS, otherwise the return value of C. + +=back + +=cut min_parallel 8; @@ -1312,7 +1477,8 @@ =head1 SEE ALSO -L. +L for easy integration into event loops, L for a +more natural syntax. =head1 AUTHOR