--- IO-AIO/AIO.pm 2008/04/16 16:45:18 1.121 +++ IO-AIO/AIO.pm 2012/07/27 19:03:18 1.231 @@ -6,7 +6,7 @@ use IO::AIO; - aio_open "/etc/passwd", O_RDONLY, 0, sub { + aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { my $fh = shift or die "/etc/passwd: $!"; ... @@ -28,34 +28,11 @@ my $grp = aio_group sub { print "all stats done\n" }; add $grp aio_stat "..." for ...; - # AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...) - open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; - my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); - - # EV integration - my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; - - # Event integration - Event->io (fd => IO::AIO::poll_fileno, - poll => 'r', - cb => \&IO::AIO::poll_cb); - - # Glib/Gtk2 integration - add_watch Glib::IO IO::AIO::poll_fileno, - in => sub { IO::AIO::poll_cb; 1 }; - - # Tk integration - Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", - readable => \&IO::AIO::poll_cb); - - # Danga::Socket integration - Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => - \&IO::AIO::poll_cb); - =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 @@ -69,8 +46,8 @@ 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 @@ -90,20 +67,18 @@ =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 { + aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { my $fh = shift or die "error while opening: $!"; @@ -122,7 +97,7 @@ print $contents; # exit event loop and program - Event::unloop; + EV::unloop; }; }; @@ -130,7 +105,7 @@ # check for sockets etc. etc. # process events as long as there are some: - Event::loop; + EV::loop; =head1 REQUEST ANATOMY AND LIFETIME @@ -190,27 +165,34 @@ use Carp (); -no warnings; -use strict 'vars'; +use common::sense; use base 'Exporter'; BEGIN { - our $VERSION = '2.61'; + our $VERSION = '4.15'; - 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_sync aio_fsync - aio_fdatasync aio_pathsync aio_readahead + our @AIO_REQ = qw(aio_sendfile aio_seek 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_realpath aio_sync + aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate + aio_pathsync aio_readahead aio_fiemap 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); + aio_chmod aio_utime aio_truncate + aio_msync aio_mtouch aio_mlock aio_mlockall + aio_statvfs + aio_wd); - our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block)); + 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 + min_parallel max_parallel max_idle idle_timeout nreqs nready npending nthreads - max_poll_time max_poll_reqs); + max_poll_time max_poll_reqs + sendfile fadvise madvise + mmap munmap munlock munlockall); + + push @AIO_REQ, qw(aio_busy); # not exported @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; @@ -220,15 +202,101 @@ =head1 FUNCTIONS -=head2 AIO REQUEST FUNCTIONS +=head2 QUICK OVERVIEW + +This section simply lists the prototypes most of the functions for +quick reference. See the following sections for function-by-function +documentation. + + aio_wd $pathname, $callback->($wd) + aio_open $pathname, $flags, $mode, $callback->($fh) + aio_close $fh, $callback->($status) + aio_seek $fh,$offset,$whence, $callback->($offs) + aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) + aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) + aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) + aio_readahead $fh,$offset,$length, $callback->($retval) + aio_stat $fh_or_path, $callback->($status) + aio_lstat $fh, $callback->($status) + aio_statvfs $fh_or_path, $callback->($statvfs) + aio_utime $fh_or_path, $atime, $mtime, $callback->($status) + aio_chown $fh_or_path, $uid, $gid, $callback->($status) + aio_chmod $fh_or_path, $mode, $callback->($status) + aio_truncate $fh_or_path, $offset, $callback->($status) + aio_allocate $fh, $mode, $offset, $len, $callback->($status) + aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) + aio_unlink $pathname, $callback->($status) + aio_mknod $pathname, $mode, $dev, $callback->($status) + aio_link $srcpath, $dstpath, $callback->($status) + aio_symlink $srcpath, $dstpath, $callback->($status) + aio_readlink $pathname, $callback->($link) + aio_realpath $pathname, $callback->($link) + aio_rename $srcpath, $dstpath, $callback->($status) + aio_mkdir $pathname, $mode, $callback->($status) + aio_rmdir $pathname, $callback->($status) + aio_readdir $pathname, $callback->($entries) + aio_readdirx $pathname, $flags, $callback->($entries, $flags) + IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST + IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN + aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) + aio_load $pathname, $data, $callback->($status) + aio_copy $srcpath, $dstpath, $callback->($status) + aio_move $srcpath, $dstpath, $callback->($status) + aio_rmtree $pathname, $callback->($status) + aio_sync $callback->($status) + aio_syncfs $fh, $callback->($status) + aio_fsync $fh, $callback->($status) + aio_fdatasync $fh, $callback->($status) + aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) + aio_pathsync $pathname, $callback->($status) + aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) + aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) + aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) + aio_mlockall $flags, $callback->($status) + aio_group $callback->(...) + aio_nop $callback->() + + $prev_pri = aioreq_pri [$pri] + aioreq_nice $pri_adjust + + IO::AIO::poll_wait + IO::AIO::poll_cb + IO::AIO::poll + IO::AIO::flush + IO::AIO::max_poll_reqs $nreqs + IO::AIO::max_poll_time $seconds + IO::AIO::min_parallel $nthreads + IO::AIO::max_parallel $nthreads + IO::AIO::max_idle $nthreads + IO::AIO::idle_timeout $seconds + IO::AIO::max_outstanding $maxreqs + IO::AIO::nreqs + IO::AIO::nready + IO::AIO::npending + + IO::AIO::sendfile $ofh, $ifh, $offset, $count + IO::AIO::fadvise $fh, $offset, $len, $advice + IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] + IO::AIO::munmap $scalar + IO::AIO::madvise $scalar, $offset, $length, $advice + IO::AIO::mprotect $scalar, $offset, $length, $protect + IO::AIO::munlock $scalar, $offset = 0, $length = undef + IO::AIO::munlockall + +=head2 API NOTES All the C calls are more or less thin wrappers around the syscall with the same name (sans C). The arguments are similar or identical, and they all accept an additional (and optional) C<$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 -syscall has been executed asynchronously. +which must be a code reference. This code reference will be called after +the syscall has been executed in an asynchronous fashion. The results +of the request will be passed as arguments to the callback (and, if an +error occured, in C<$!>) - for most requests the syscall return code (e.g. +most syscalls return C<-1> on error, unlike perl, which usually delivers +"false"). + +Some requests (such as C) pass the actual results and +communicate failures by passing C. All functions expecting a filehandle keep a copy of the filehandle internally until the request has finished. @@ -236,22 +304,27 @@ All functions return request objects of type L that allow further manipulation of those requests while they are in-flight. -The pathnames you pass to these routines I be absolute and -encoded as octets. The reason for the former is that at the time the -request is being executed, the current working directory could have -changed. Alternatively, you can make sure that you never change the -current working directory anywhere in the program and then use relative -paths. +The pathnames you pass to these routines I be absolute. The +reason for this is that at the time the request is being executed, the +current working directory could have changed. Alternatively, you can +make sure that you never change the current working directory anywhere +in the program and then use relative paths. You can also take advantage +of IO::AIOs working directory abstraction, that lets you specify paths +relative to some previously-opened "working directory object" - see the +description of the C class later in this document. To encode pathnames as octets, either make sure you either: a) always pass in filenames you got from outside (command line, readdir etc.) without -tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode -your pathnames to the locale (or other) encoding in effect in the user -environment, d) use Glib::filename_from_unicode on unicode filenames or e) -use something else to ensure your scalar has the correct contents. +tinkering, b) are in your native filesystem encoding, c) use the Encode +module and encode your pathnames to the locale (or other) encoding in +effect in the user environment, d) use Glib::filename_from_unicode on +unicode filenames or e) 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. + +=head2 AIO REQUEST FUNCTIONS =over 4 @@ -308,7 +381,7 @@ Example: - aio_open "/etc/passwd", O_RDONLY, 0, sub { + aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { if ($_[0]) { print "open successful, fh is $_[0]\n"; ... @@ -317,6 +390,15 @@ } }; +In addition to all the common open modes/flags (C, C, +C, C, C, C and C), the +following POSIX and non-POSIX constants are available (missing ones on +your system are, as usual, C<0>): + +C, C, C, C, C, C, +C, C, C, C, C, +C, C and C. + =item aio_close $fh, $callback->($status) @@ -335,20 +417,44 @@ =cut +=item aio_seek $fh, $offset, $whence, $callback->($offs) + +Seeks the filehandle to the new C<$offset>, similarly to perl's +C. The C<$whence> can use the traditional values (C<0> for +C, C<1> for C or C<2> for +C). + +The resulting absolute offset will be passed to the callback, or C<-1> in +case of an error. + +In theory, the C<$whence> constants could be different than the +corresponding values from L, but perl guarantees they are the same, +so don't panic. + +As a GNU/Linux (and maybe Solaris) extension, also the constants +C and C are available, if they +could be found. No guarantees about suitability for use in C or +Perl's C can be made though, although I would naively assume they +"just work". + =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<$length> is undefined in C, use the remaining length of C<$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>. @@ -372,22 +478,40 @@ reading at byte offset C<$in_offset>, and starts writing at the current file offset of C<$out_fh>. Because of that, it is not safe to issue more than one C per C<$out_fh>, as they will interfere with each -other. +other. The same C<$in_fh> works fine though, as this function does not +move or use the file offset of C<$in_fh>. -This call tries to make use of a native C syscall to provide -zero-copy operation. For this to work, C<$out_fh> should refer to a -socket, and C<$in_fh> should refer to mmap'able file. - -If the native sendfile call fails or is not implemented, it will be -emulated, so you can call C on any type of filehandle -regardless of the limitations of the operating system. - -Please note, however, that C can read more bytes from -C<$in_fh> than are written, and there is no way to find out how many -bytes have been read from C alone, as C only -provides the number of bytes written to C<$out_fh>. Only if the result -value equals C<$length> one can assume that C<$length> bytes have been -read. +Please note that C can read more bytes from C<$in_fh> than +are written, and there is no way to find out how many more bytes have been +read from C alone, as C only provides the +number of bytes written to C<$out_fh>. Only if the result value equals +C<$length> one can assume that C<$length> bytes have been read. + +Unlike with other C functions, it makes a lot of sense to use +C on non-blocking sockets, as long as one end (typically +the C<$in_fh>) is a file - the file I/O will then be asynchronous, while +the socket I/O will be non-blocking. Note, however, that you can run +into a trap where C reads some data with readahead, then +fails to write all data, and when the socket is ready the next time, the +data in the cache is already lost, forcing C to again hit +the disk. Explicit C + C let's you better control +resource usage. + +This call tries to make use of a native C-like syscall to +provide zero-copy operation. For this to work, C<$out_fh> should refer to +a socket, and C<$in_fh> should refer to an mmap'able file. + +If a native sendfile cannot be found or it fails with C, +C, C, C, C, C or +C, it will be emulated, so you can call C on any +type of filehandle regardless of the limitations of the operating system. + +As native sendfile syscalls (as practically any non-POSIX interface hacked +together in a hurry to improve benchmark numbers) tend to be rather buggy +on many systems, this implementation tries to work around some known bugs +in Linux and FreeBSD kernels (probably others, too), but that might fail, +so you really really should check the return value of C - +fewre bytes than expected might have been transferred. =item aio_readahead $fh,$offset,$length, $callback->($retval) @@ -420,6 +544,15 @@ error when stat'ing a large file, the results will be silently truncated unless perl itself is compiled with large file support. +To help interpret the mode and dev/rdev stat values, IO::AIO offers the +following constants and functions (if not implemented, the constants will +be C<0> and the functions will either C or fall back on traditional +behaviour). + +C, C, C, C, C, C, +C, C, C, C, +C, C. + Example: Print the length of F: aio_stat "/etc/passwd", sub { @@ -428,6 +561,51 @@ }; +=item aio_statvfs $fh_or_path, $callback->($statvfs) + +Works like the POSIX C or C syscalls, depending on +whether a file handle or path was passed. + +On success, the callback is passed a hash reference with the following +members: C, C, C, C, C, C, +C, C, C, C and C. On failure, C +is passed. + +The following POSIX IO::AIO::ST_* constants are defined: C and +C. + +The following non-POSIX IO::AIO::ST_* flag masks are defined to +their correct value when available, or to C<0> on systems that do +not support them: C, C, C, +C, C, C, C, C, +C and C. + +Example: stat C and dump out the data if successful. + + aio_statvfs "/wd", sub { + my $f = $_[0] + or die "statvfs: $!"; + + use Data::Dumper; + say Dumper $f; + }; + + # result: + { + bsize => 1024, + bfree => 4333064312, + blocks => 10253828096, + files => 2050765568, + flag => 4096, + favail => 2042092649, + bavail => 4333064312, + ffree => 2042092649, + namemax => 255, + frsize => 1024, + fsid => 1810 + } + + =item aio_utime $fh_or_path, $atime, $mtime, $callback->($status) Works like perl's C function (including the special case of $atime @@ -464,6 +642,22 @@ Works like truncate(2) or ftruncate(2). +=item aio_allocate $fh, $mode, $offset, $len, $callback->($status) + +Allocates or freed disk space according to the C<$mode> argument. See the +linux C docuemntation for details. + +C<$mode> can currently be C<0> or C +to allocate space, or C, to deallocate a file range. + +The file system block size used by C is presumably the +C returned by C. + +If C isn't available or cannot be emulated (currently no +emulation will be attempted), passes C<-1> and sets C<$!> to C. + + =item aio_chmod $fh_or_path, $mode, $callback->($status) Works like perl's C function. @@ -475,7 +669,7 @@ result code. -=item aio_mknod $path, $mode, $dev, $callback->($status) +=item aio_mknod $pathname, $mode, $dev, $callback->($status) [EXPERIMENTAL] @@ -483,8 +677,10 @@ The only (POSIX-) portable way of calling this function is: - aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... + aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ... +See C for info about some potentially helpful extra constants +and functions. =item aio_link $srcpath, $dstpath, $callback->($status) @@ -498,13 +694,23 @@ the path C<$dstpath> and call the callback with the result code. -=item aio_readlink $path, $callback->($link) +=item aio_readlink $pathname, $callback->($link) Asynchronously read the symlink specified by C<$path> and pass it to the callback. If an error occurs, nothing or undef gets passed to the callback. +=item aio_realpath $pathname, $callback->($path) + +Asynchronously make the path absolute and resolve any symlinks in +C<$path>. The resulting path only consists of directories (Same as +L). + +This request can be used to get the absolute path of the current working +directory by passing it a path of F<.> (a single dot). + + =item aio_rename $srcpath, $dstpath, $callback->($status) Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as @@ -530,11 +736,77 @@ 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 one to +tune behaviour and output format. In case of an error, C<$entries> will be +C. + +The flags are a combination of the following constants, ORed together (the +flags will also be passed to the callback, possibly modified): + +=over 4 + +=item IO::AIO::READDIR_DENTS + +When this flag is off, then the callback gets an arrayref consisting of +names only (as with C), otherwise it gets an arrayref with +C<[$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: -=item aio_load $path, $data, $callback->($status) +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, in optimal stat order. 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 names +beginning with ".", or otherwise names with no dots, of which names 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<$type>'s found were +C. The absence of this flag therefore indicates that all +C<$type>'s are known, which can be used to speed up some algorithms. + +=back + + +=item aio_load $pathname, $data, $callback->($status) This is a composite request that tries to fully load the given file into memory. Status is the same as with aio_read. @@ -542,35 +814,33 @@ =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), $$data, 0, sub { + $grp->result ($_[0]); }; + }; - $grp - } + $grp } =item aio_copy $srcpath, $dstpath, $callback->($status) Try to copy the I (directories not supported as either source or destination) from C<$srcpath> to C<$dstpath> and call the callback with -the C<0> (error) or C<-1> ok. +a status of C<0> (ok) or C<-1> (error, see C<$!>). -This is a composite request that it creates the destination file with +This is a composite request that creates the destination file with mode 0200 and copies the contents of the source file into it using C, followed by restoring atime, mtime, access mode and uid/gid, in that order. @@ -582,97 +852,106 @@ =cut sub aio_copy($$;$) { - aio_block { - my ($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 block 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; + 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; + my $ch = sub { aioreq_pri $pri; - add $grp aio_close $dst_fh; - } else { - $grp->result (-1); - close $src_fh; - close $dst_fh; + 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; - add $grp aio_unlink $dst; - } - }; - } else { - $grp->result (-1); - } - }, + 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); + } + }, - } else { - $grp->result (-1); - } - }; + } else { + $grp->result (-1); + } + }; - $grp - } + $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. +a status of C<0> (ok) or C<-1> (error, see C<$!>). -This is a composite request that tries to rename(2) the file first. If -rename files with C, it copies the file with C and, if -that is successful, unlinking the C<$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; + 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]); - - 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 - } + unless ($_[0]) { + aioreq_pri $pri; + add $grp aio_unlink $src; + } + }; + } else { + $grp->result ($_[0]); + } + }; + + $grp } -=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) +=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) Scans a directory (similar to C) but additionally tries to efficiently separate the entries of directory C<$path> into two sets of @@ -699,20 +978,24 @@ 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 -seperately). This is often faster than stat'ing the entry itself because +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 +separately). 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. @@ -727,31 +1010,38 @@ =cut sub aio_scandir($$;$) { - aio_block { - my ($path, $maxreq, $cb) = @_; + my ($path, $maxreq, $cb) = @_; + + my $pri = aioreq_pri; + + my $grp = aio_group $cb; - my $pri = aioreq_pri; + $maxreq = 4 if $maxreq <= 0; - my $grp = aio_group $cb; + # get a wd object + aioreq_pri $pri; + add $grp aio_wd $path, sub { + $_[0] + or return $grp->result (); - $maxreq = 4 if $maxreq <= 0; + my $wd = [shift, "."]; # stat once aioreq_pri $pri; - add $grp aio_stat $path, sub { + add $grp aio_stat $wd, sub { return $grp->result () if $_[0]; my $now = time; my $hash1 = join ":", (stat _)[0,1,3,7,9]; # read the directory entries aioreq_pri $pri; - add $grp aio_readdir $path, sub { + add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub { my $entries = shift or return $grp->result (); # stat the dir another time aioreq_pri $pri; - add $grp aio_stat $path, sub { + add $grp aio_stat $wd, sub { my $hash2 = join ":", (stat _)[0,1,3,7,9]; my $ndirs; @@ -761,18 +1051,11 @@ $ndirs = -1; } else { # if nlink == 2, we are finished - # on non-posix-fs's, we rely on nlink < 2 + # for 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]; - my (@dirs, @nondirs); my $statgrp = add $grp aio_group sub { @@ -782,16 +1065,18 @@ limit $statgrp $maxreq; feed $statgrp sub { return unless @$entries; - my $entry = pop @$entries; + my $entry = shift @$entries; aioreq_pri $pri; - add $statgrp aio_stat "$path/$entry/.", sub { + $wd->[1] = "$entry/."; + add $statgrp aio_stat $wd, sub { if ($_[0] < 0) { push @nondirs, $entry; } else { # need to check for real directory aioreq_pri $pri; - add $statgrp aio_lstat "$path/$entry", sub { + $wd->[1] = $entry; + add $statgrp aio_lstat $wd, sub { if (-d _) { push @dirs, $entry; @@ -809,12 +1094,12 @@ }; }; }; + }; - $grp - } + $grp } -=item aio_rmtree $path, $callback->($status) +=item aio_rmtree $pathname, $callback->($status) Delete a directory tree starting (and including) C<$path>, return the status of the final C only. This is a composite request that @@ -825,30 +1110,28 @@ sub aio_rmtree; sub aio_rmtree($;$) { - aio_block { - my ($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) @@ -868,46 +1151,172 @@ 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_pathsync $path, $callback->($status) +=item aio_syncfs $fh, $callback->($status) + +Asynchronously call the syncfs syscall to sync the filesystem associated +to the given filehandle and call the callback with the syncfs result +code. If syncfs is not available, calls sync(), but returns C<-1> and sets +errno to C nevertheless. + +=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 $pathname, $callback->($status) This request tries to open, fsync and close the given path. This is a -composite request intended tosync directories after directory operations +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($;$) { - 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_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_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); - } - }; + aioreq_pri $pri; + add $grp aio_close $fh; + }; + } else { + $grp->result (-1); + } + }; - $grp - } + $grp } +=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) + +This is a rather advanced IO::AIO call, which only works on mmap(2)ed +scalars (see the C function, although it also works on data +scalars managed by the L or L modules, note that the +scalar must only be modified in-place while an aio operation is pending on +it). + +It calls the C function of your OS, if available, with the memory +area starting at C<$offset> in the string and ending C<$length> bytes +later. If C<$length> is negative, counts from the end, and if C<$length> +is C, then it goes till the end of the string. The flags can be +a combination of C, C and +C. + +=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) + +This is a rather advanced IO::AIO call, which works best on mmap(2)ed +scalars. + +It touches (reads or writes) all memory pages in the specified +range inside the scalar. All caveats and parameters are the same +as for C, above, except for flags, which must be either +C<0> (which reads all pages and ensures they are instantiated) or +C, which modifies the memory page s(by reading and +writing an octet from it, which dirties the page). + +=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) + +This is a rather advanced IO::AIO call, which works best on mmap(2)ed +scalars. + +It reads in all the pages of the underlying storage into memory (if any) +and locks them, so they are not getting swapped/paged out or removed. + +If C<$length> is undefined, then the scalar will be locked till the end. + +On systems that do not implement C, this function returns C<-1> +and sets errno to C. + +Note that the corresponding C is synchronous and is +documented under L. + +Example: open a file, mmap and mlock it - both will be undone when +C<$data> gets destroyed. + + open my $fh, "<", $path or die "$path: $!"; + my $data; + IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; + aio_mlock $data; # mlock in background + +=item aio_mlockall $flags, $callback->($status) + +Calls the C function with the given C<$flags> (a combination of +C and C). + +On systems that do not implement C, this function returns C<-1> +and sets errno to C. + +Note that the corresponding C is synchronous and is +documented under L. + +Example: asynchronously lock all current and future pages into memory. + + aio_mlockall IO::AIO::MCL_FUTURE; + +=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) + +Queries the extents of the given file (by calling the Linux FIEMAP ioctl, +see L for details). If the +C is not available on your OS, then this request will fail with +C. + +C<$start> is the starting offset to query extents for, C<$length> is the +size of the range to query - if it is C, then the whole file will +be queried. + +C<$flags> is a combination of flags (C or +C - C is also +exported), and is normally C<0> or C to query +the data portion. + +C<$count> is the maximum number of extent records to return. If it is +C, then IO::AIO queries all extents of the file. As a very special +case, if it is C<0>, then the callback receives the number of extents +instead of the extents themselves. + +If an error occurs, the callback receives no arguments. The special +C value C is available to test for flag errors. + +Otherwise, the callback receives an array reference with extent +structures. Each extent structure is an array reference itself, with the +following members: + + [$logical, $physical, $length, $flags] + +Flags is any combination of the following flag values (typically either C<0> +or C (1)): + +C, C, +C, C, +C, C, +C, C, +C, C or +C. + =item aio_group $callback->(...) This is a very special aio request: Instead of doing something, it is a @@ -954,6 +1363,125 @@ =back + +=head2 IO::AIO::WD - multiple working directories + +Your process only has one current working directory, which is used by all +threads. This makes it hard to use relative paths (some other component +could call C at any time, and it is hard to control when the path +will be used by IO::AIO). + +One solution for this is to always use absolute paths. This usually works, +but can be quite slow (the kernel has to walk the whole path on every +access), and can also be a hassle to implement. + +Newer POSIX systems have a number of functions (openat, fdopendir, +futimensat and so on) that make it possible to specify working directories +per operation. + +For portability, and because the clowns who "designed", or shall I write, +perpetrated this new interface were obviously half-drunk, this abstraction +cannot be perfect, though. + +IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD +object. This object stores the canonicalised, absolute version of the +path, and on systems that allow it, also a directory file descriptor. + +Everywhere where a pathname is accepted by IO::AIO (e.g. in C +or C), one can specify an array reference with an IO::AIO::WD +object and a pathname instead (or the IO::AIO::WD object alone, which +gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the +IO::AIO::WD object is ignored, otherwise the pathname is resolved relative +to that IO::AIO::WD object. + +For example, to get a wd object for F and then stat F +inside, you would write: + + aio_wd "/etc", sub { + my $etcdir = shift; + + # although $etcdir can be undef on error, there is generally no reason + # to check for errors here, as aio_stat will fail with ENOENT + # when $etcdir is undef. + + aio_stat [$etcdir, "passwd"], sub { + # yay + }; + }; + +That C is a request and not a normal function shows that creating +an IO::AIO::WD object is itself a potentially blocking operation, which is +why it is done asynchronously. + +To stat the directory obtained with C above, one could write +either of the following three request calls: + + aio_lstat "/etc" , sub { ... # pathname as normal string + aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself) + aio_lstat $wd , sub { ... # shorthand for the previous + +As with normal pathnames, IO::AIO keeps a copy of the working directory +object and the pathname string, so you could write the following without +causing any issues due to C<$path> getting reused: + + my $path = [$wd, undef]; + + for my $name (qw(abc def ghi)) { + $path->[1] = $name; + aio_stat $path, sub { + # ... + }; + } + +There are some caveats: when directories get renamed (or deleted), the +pathname string doesn't change, so will point to the new directory (or +nowhere at all), while the directory fd, if available on the system, +will still point to the original directory. Most functions accepting a +pathname will use the directory fd on newer systems, and the string on +older systems. Some functions (such as realpath) will always rely on the +string form of the pathname. + +So this fucntionality is mainly useful to get some protection against +C, to easily get an absolute path out of a relative path for future +reference, and to speed up doing many operations in the same directory +(e.g. when stat'ing all files in a directory). + +The following functions implement this working directory abstraction: + +=over 4 + +=item aio_wd $pathname, $callback->($wd) + +Asynchonously canonicalise the given pathname and convert it to an +IO::AIO::WD object representing it. If possible and supported on the +system, also open a directory fd to speed up pathname resolution relative +to this working directory. + +If something goes wrong, then C is passwd to the callback instead +of a working directory object and C<$!> is set appropriately. Since +passing C as working directory component of a pathname fails the +request with C, there is often no need for error checking in the +C callback, as future requests using the value will fail in the +expected way. + +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 IO::AIO::CWD + +This is a compiletime constant (object) that represents the process +current working directory. + +Specifying this object as working directory object for a pathname is as +if the pathname would be specified directly, without a directory object, +e.g., these calls are functionally identical: + + aio_stat "somefile", sub { ... }; + aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; + +=back + + =head2 IO::AIO::REQ CLASS All non-aggregate C functions return an object of this class when @@ -966,8 +1494,9 @@ 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->(...) @@ -1028,10 +1557,11 @@ 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 @@ -1050,6 +1580,9 @@ Cancel all subrequests and clears any feeder, but not the group request itself. Useful when you queued a lot of events but got a result early. +The group request will finish normally (you cannot add requests to the +group). + =item $grp->result (...) Set the result value(s) that will be passed to the group callback when all @@ -1074,8 +1607,8 @@ 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 +this might starve other requests for a potentially long time. For example, +C might generate hundreds of thousands of C requests, delaying any later requests for a long time. To avoid this, and allow incremental generation of requests, you can @@ -1090,7 +1623,8 @@ 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: @@ -1112,6 +1646,9 @@ 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 @@ -1123,29 +1660,67 @@ =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. +Process some outstanding events on the result pipe. You have to call +this regularly. Returns C<0> if all events could be processed (or there +were no events to process), 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. + +Apart from calling C when the event filehandle becomes +ready, it can be beneficial to call this function from loops which submit +a lot of requests, to make sure the results get processed when they become +available and not just when the loop is finished and the event loop takes +over again. This function returns very fast when there are no outstanding +requests. 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, cb => \&IO::AIO::poll_cb); +=item IO::AIO::poll_wait + +If there are any outstanding requests and none of them in the result +phase, wait till the result filehandle becomes ready for reading (simply +does a C on the filehandle. This is useful if you want to -synchronously wait for some requests to finish). - -See C for an example. - -=item IO::AIO::poll - -Waits until some requests have been handled. - -Returns the number of requests processed, but is otherwise strictly -equivalent to: - - IO::AIO::poll_wait, IO::AIO::poll_cb - -=item IO::AIO::flush - -Wait till all outstanding AIO requests have been handled. - -Strictly equivalent to: - - IO::AIO::poll_wait, IO::AIO::poll_cb - while IO::AIO::nreqs; - =back =head3 CONTROLLING THE NUMBER OF THREADS @@ -1248,10 +1796,11 @@ =item IO::AIO::max_idle $nthreads -Limit the number of threads (default: 4) that are allowed to idle (i.e., -threads that did not get a request to process within 10 seconds). That -means if a thread becomes idle while C<$nthreads> other threads are also -idle, it will free its resources and exit. +Limit the number of threads (default: 4) that are allowed to idle +(i.e., threads that did not get a request to process within the idle +timeout (default: 10 seconds). That means if a thread becomes idle while +C<$nthreads> other threads are also idle, it will free its resources and +exit. This is useful when you allow a large number of threads (e.g. 100 or 1000) to allow for extremely high load situations, but want to free resources @@ -1261,23 +1810,45 @@ 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::idle_timeout $seconds + +Sets the minimum idle timeout (default 10) after which worker threads are +allowed to exit. SEe C. + +=item IO::AIO::max_outstanding $maxreqs + +Sets the maximum number of outstanding requests to C<$nreqs>. If +you do queue up more than this number of requests, the next call to +C (and other functions calling C, such as +C or C) will block until the limit is no +longer exceeded. + +In other words, this setting does not enforce a queue limit, but can be +used to make poll functions block if the limit is exceeded. 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 -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. - -The default value is very large, so there is no practical limit on the -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 -as a stop gap to shield against fatal memory overflow (with large values). +It's main use is in scripts without an event loop - when you want to stat +a lot of files, you can write somehting like this: + + IO::AIO::max_outstanding 32; + + for my $path (...) { + aio_stat $path , ...; + IO::AIO::poll_cb; + } + + IO::AIO::flush; + +The call to C inside the loop will normally return instantly, but +as soon as more thna C<32> reqeusts are in-flight, it will block until +some requests have been handled. This keeps the loop from pushing a large +number of C requests onto the queue. + +The default value for C is very large, so there is no +practical limit on the number of outstanding requests. =back @@ -1307,6 +1878,142 @@ =back +=head3 MISCELLANEOUS FUNCTIONS + +IO::AIO implements some functions that might be useful, but are not +asynchronous. + +=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 its +manpage for details). The following advice constants are +available: C, C, +C, C, +C, C. + +On systems that do not implement C, this function returns +ENOSYS, otherwise the return value of C. + +=item IO::AIO::madvise $scalar, $offset, $len, $advice + +Simply calls the C function (see its +manpage for details). The following advice constants are +available: C, C, +C, C, C. + +On systems that do not implement C, this function returns +ENOSYS, otherwise the return value of C. + +=item IO::AIO::mprotect $scalar, $offset, $len, $protect + +Simply calls the C function on the preferably AIO::mmap'ed +$scalar (see its manpage for details). The following protect +constants are available: C, C, +C, C. + +On systems that do not implement C, this function returns +ENOSYS, otherwise the return value of C. + +=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] + +Memory-maps a file (or anonymous memory range) and attaches it to the +given C<$scalar>, which will act like a string scalar. Returns true on +success, and false otherwise. + +The only operations allowed on the scalar are C/C that don't +change the string length, and most read-only operations such as copying it +or searching it with regexes and so on. + +Anything else is unsafe and will, at best, result in memory leaks. + +The memory map associated with the C<$scalar> is automatically removed +when the C<$scalar> is destroyed, or when the C or +C functions are called. + +This calls the C(2) function internally. See your system's manual +page for details on the C<$length>, C<$prot> and C<$flags> parameters. + +The C<$length> must be larger than zero and smaller than the actual +filesize. + +C<$prot> is a combination of C, C, +C and/or C, + +C<$flags> can be a combination of C or +C, or a number of system-specific flags (when +not available, the are defined as 0): C +(which is set to C if your system only provides this +constant), C, C, +C, C or +C + +If C<$fh> is C, then a file descriptor of C<-1> is passed. + +C<$offset> is the offset from the start of the file - it generally must be +a multiple of C and defaults to C<0>. + +Example: + + use Digest::MD5; + use IO::AIO; + + open my $fh, ". + +=item IO::AIO::munlock $scalar, $offset = 0, $length = undef + +Calls the C function, undoing the effects of a previous +C call (see its description for details). + +=item IO::AIO::munlockall + +Calls the C function. + +On systems that do not implement C, this function returns +ENOSYS, otherwise the return value of C. + +=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags + +Calls the GNU/Linux C syscall, if available. If C<$r_off> or +C<$w_off> are C, then C is passed for these, otherwise they +should be the file offset. + +C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might +silently corrupt the data in this case. + +The following symbol flag values are available: C, +C, C and +C. + +See the C manpage for details. + +=item IO::AIO::tee $r_fh, $w_fh, $length, $flags + +Calls the GNU/Linux C syscall, see it's manpage and the +description for C above for details. + +=back + =cut min_parallel 8; @@ -1315,21 +2022,69 @@ 1; +=head1 EVENT LOOP INTEGRATION + +It is recommended to use L to integrate IO::AIO +automatically into many event loops: + + # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) + use AnyEvent::AIO; + +You can also integrate IO::AIO manually into many event loops, here are +some examples of how to do this: + + # 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, + poll => 'r', + cb => \&IO::AIO::poll_cb); + + # Glib/Gtk2 integration + add_watch Glib::IO IO::AIO::poll_fileno, + in => sub { IO::AIO::poll_cb; 1 }; + + # Tk integration + Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", + readable => \&IO::AIO::poll_cb); + + # Danga::Socket integration + Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => + \&IO::AIO::poll_cb); + =head2 FORK BEHAVIOUR -This module should do "the right thing" when the process using it forks: +Usage of pthreads in a program changes the semantics of fork +considerably. Specifically, only async-safe functions can be called after +fork. Perl doesn't know about this, so in general, you cannot call fork +with defined behaviour in perl if pthreads are involved. IO::AIO uses +pthreads, so this applies, but many other extensions and (for inexplicable +reasons) perl itself often is linked against pthreads, so this limitation +applies to quite a lot of perls. + +This module no longer tries to fight your OS, or POSIX. That means IO::AIO +only works in the process that loaded it. Forking is fully supported, but +using IO::AIO in the child is not. + +You might get around by not I IO::AIO before (or after) +forking. You could also try to call the L function in the +child: -Before the fork, IO::AIO enters a quiescent state where no requests -can be added in other threads and no results will be processed. After -the fork the parent simply leaves the quiescent state and continues -request/result processing, while the child frees the request/result queue -(so that the requests started before the fork will only be handled in the -parent). Threads will be started on demand until the limit set in the -parent process has been reached again. - -In short: the parent will, after a short pause, continue as if fork had -not been called, while the child will act as if IO::AIO has not been used -yet. +=over 4 + +=item IO::AIO::reinit + +Abandons all current requests and I/O threads and simply reinitialises all +data structures. This is not an operation supported by any standards, but +happens to work on GNU/Linux and some newer BSD systems. + +The only reasonable use for this function is to call it after forking, if +C was used in the parent. Calling it while IO::AIO is active in +the process will result in undefined behaviour. Calling it at any time +will also result in any undefined (by POSIX) behaviour. + +=back =head2 MEMORY USAGE @@ -1356,7 +2111,8 @@ =head1 SEE ALSO -L. +L for easy integration into event loops, L for a +more natural syntax. =head1 AUTHOR