[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC vs.
Revision 1.172 by root, Thu Jan 7 18:08:21 2010 UTC

  $req->cancel; # cancel request if still in queue
  my $grp = aio_group sub { print "all stats done\n" };
  add $grp aio_stat "..." for ...;
- # AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
+ # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
- open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
+ use AnyEvent::AIO;
- 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;
+ 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);
                              \&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<libeio>
+(L<http://software.schmorp.de/pkg/libeio.html>).
 Asynchronous means that operations that can normally block your program
 (e.g. reading from disk) will be done asynchronously: the operation
 will still block, but you can do something else in the meantime. This
 is extremely useful for programs that need to stay interactive even
 on a RAID volume or over NFS when you do a number of stat operations
 concurrently.
 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
+support nonblocking operation (again, sockets, pipes etc.) is
-inefficient. Use an event loop for that (such as the L<Event|Event>
+very inefficient. Use an event loop for that (such as the L<EV>
 module): IO::AIO will naturally fit into such an event loop itself.
 In this version, a number of threads are started that execute your
 requests and signal their completion. You don't need thread support
 in perl, and the threads created by this module will not be visible
 yourself, always call C<poll_cb> from within the same thread, or never
 call C<poll_cb> (or other C<aio_> functions) recursively.
 =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</etc/passwd> asynchronously:
    use Fcntl;
-   use Event;
+   use EV;
    use IO::AIO;
-   # register the IO::AIO callback with Event
+   # register the IO::AIO callback with EV
-   Event->io (fd => IO::AIO::poll_fileno,
+   my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
-              poll => 'r',
-              cb => \&IO::AIO::poll_cb);
    # queue the request to open /etc/passwd
    aio_open "/etc/passwd", O_RDONLY, 0, sub {
       my $fh = shift
          or die "error while opening: $!";
          # file contents now in $contents
          print $contents;
          # exit event loop and program
-         Event::unloop;
+         EV::unloop;
       };
    };
    # possibly queue up other requests, or open GUI windows,
    # check for sockets etc. etc.
    # process events as long as there are some:
-   Event::loop;
+   EV::loop;
 =head1 REQUEST ANATOMY AND LIFETIME
 Every C<aio_*> function creates a request. which is a C data structure not
 directly visible to Perl.
 package IO::AIO;
 use Carp ();
-no warnings;
+use common::sense;
-use strict 'vars';
 use base 'Exporter';
 BEGIN {
-   our $VERSION = '3.0';
+   our $VERSION = '3.4';
    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_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
                      aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
-                     aio_fdatasync aio_pathsync aio_readahead
+                     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);
+                     aio_chmod aio_utime aio_truncate
+                     aio_msync aio_mtouch aio_statvfs);
    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';
    require XSLoader;
    XSLoader::load ("IO::AIO", $VERSION);
 All the C<aio_*> calls are more or less thin wrappers around the syscall
 with the same name (sans C<aio_>). The arguments are similar or identical,
 and they all accept an additional (and optional) C<$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
+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
 internally until the request has finished.
 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.
 =over 4
 =item $prev_pri = aioreq_pri [$pri]
 =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<$offset>
+Reads or writes C<$length> bytes from or to the specified C<$fh> and
-into the scalar given by C<$data> and offset C<$dataoffset> and calls the
+C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
-callback without the actual number of bytes read (or -1 on error, just
+and calls the callback without the actual number of bytes read (or -1 on
-like the syscall).
+error, just like the syscall).
+C<aio_read> will, like C<sysread>, 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<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
+If C<$length> is undefined in C<aio_write>, use the remaining length of
+C<$data>.
 If C<$dataoffset> is less than zero, it will be counted from the end of
 C<$data>.
 The C<$data> scalar I<MUST NOT> be modified in any way while the request
 This call tries to make use of a native C<sendfile> syscall to provide
 zero-copy operation. For this to work, C<$out_fh> should refer to a
 socket, and C<$in_fh> should refer to mmap'able file.
-If the native sendfile call fails or is not implemented, it will be
+If a native sendfile cannot be found or it fails with C<ENOSYS>,
+C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
-emulated, so you can call C<aio_sendfile> on any type of filehandle
+it will be emulated, so you can call C<aio_sendfile> on any type of
-regardless of the limitations of the operating system.
+filehandle regardless of the limitations of the operating system.
 Please note, however, that C<aio_sendfile> can read more bytes from
 C<$in_fh> than are written, and there is no way to find out how many
 bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
 provides the number of bytes written to C<$out_fh>. Only if the result
       $_[0] and die "stat failed: $!";
       print "size is ", -s _, "\n";
    };
+=item aio_statvfs  $fh_or_path, $callback->($statvfs)
+Works like the POSIX C<statvfs> or C<fstatvfs> 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<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
+C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
+is passed.
+The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
+C<ST_NOSUID>.
+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<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
+C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
+C<ST_NODIRATIME> and C<ST_RELATIME>.
+Example: stat C</wd> 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<utime> function (including the special case of $atime
 and $mtime being undef). Fractional times are supported if the underlying
 syscalls support them.
 Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
 directory (i.e. opendir + readdir + closedir). The entries will not be
 sorted, and will B<NOT> include the C<.> and C<..> entries.
-The callback a single argument which is either C<undef> or an array-ref
+The callback is passed a single argument which is either C<undef> or an
-with the filenames.
+array-ref with the filenames.
+=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
+Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
+behaviour and output format. In case of an error, C<$entries> will be
+C<undef>.
+The flags are a combination of the following constants, ORed together (the
+flags will also be passed to the callback, possibly modified):
+=over 4
+=item IO::AIO::READDIR_DENTS
+When this flag is off, then the callback gets an arrayref with of names
+only (as with C<aio_readdir>), otherwise it gets an arrayref with
+C<[$name, $type, $inode]> arrayrefs, each describing a single directory
+entry in more detail.
+C<$name> is the name of the entry.
+C<$type> is one of the C<IO::AIO::DT_xxx> constants:
+C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
+C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
+C<IO::AIO::DT_WHT>.
+C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
+know, you have to run stat yourself. Also, for speed reasons, the C<$type>
+scalars are read-only: you can not modify them.
+C<$inode> is the inode number (which might not be exact on systems with 64
+bit inode numbers and 32 bit perls). This field has unspecified content on
+systems that do not deliver the inode information.
+=item IO::AIO::READDIR_DIRS_FIRST
+When this flag is set, then the names will be returned in an order where
+likely directories come first. This is useful when you need to quickly
+find directories, or you want to find all directories while avoiding to
+stat() each entry.
+If the system returns type information in readdir, then this is used
+to find directories directly.  Otherwise, likely directories are files
+beginning with ".", or otherwise files with no dots, of which files with
+short names are tried first.
+=item IO::AIO::READDIR_STAT_ORDER
+When this flag is set, then the names will be returned in an order
+suitable for stat()'ing each one. That is, when you plan to stat()
+all files in the given directory, then the returned order will likely
+be fastest.
+If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
+the likely dirs come first, resulting in a less optimal stat order.
+=item IO::AIO::READDIR_FOUND_UNKNOWN
+This flag should not be set when calling C<aio_readdirx>. Instead, it
+is being set by C<aio_readdirx>, when any of the C<$type>'s found were
+C<IO::AIO::DT_UNKNOWN>. 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)
 This is a composite request that tries to fully load the given file into
 =item aio_copy $srcpath, $dstpath, $callback->($status)
 Try to copy the I<file> (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<aio_sendfile>, followed by restoring atime, mtime, access mode and
 uid/gid, in that order.
 If an error occurs, the partial destination file will be unlinked, if
    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;
+         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.
+                     my $ch = sub {
-                     utime $stat[8], $stat[9], $dst;
+                        aioreq_pri $pri;
-                     chmod $stat[2] & 07777, $dst_fh;
+                        add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
-                     chown $stat[4], $stat[5], $dst_fh;
+                           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_close $dst_fh;
+                     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;
 =item aio_move $srcpath, $dstpath, $callback->($status)
 Try to move the I<file> (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<$!>).
-This is a composite request that tries to rename(2) the file first. If
+This is a composite request that tries to rename(2) the file first; if
-rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
+rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
-that is successful, unlinking the C<$srcpath>.
+that is successful, unlinks the C<$srcpath>.
 =cut
 sub aio_move($$;$) {
    my ($src, $dst, $cb) = @_;
 Implementation notes.
 The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
+If readdir returns file type information, then this is used directly to
+find directories.
-After reading the directory, the modification time, size etc. of the
+Otherwise, after reading the directory, the modification time, size etc.
-directory before and after the readdir is checked, and if they match (and
+of the directory before and after the readdir is checked, and if they
-isn't the current time), the link count will be used to decide how many
+match (and isn't the current time), the link count will be used to decide
-entries are directories (if >= 2). Otherwise, no knowledge of the number
+how many entries are directories (if >= 2). Otherwise, no knowledge of the
-of subdirectories will be assumed.
+number of subdirectories will be assumed.
-Then entries will be sorted into likely directories (everything without
+Then entries will be sorted into likely directories a non-initial dot
-a non-initial dot currently) and likely non-directories (everything
+currently) and likely non-directories (see C<aio_readdirx>). Then every
-else). Then every entry plus an appended C</.> will be C<stat>'ed,
+entry plus an appended C</.> will be C<stat>'ed, likely directories first,
-likely directories first. If that succeeds, it assumes that the entry
+in order of their inode numbers. If that succeeds, it assumes that the
-is a directory or a symlink to directory (which will be checked
+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.
 This only works with certainty on POSIX (= UNIX) filesystems, which
       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 $path, READDIR_DIRS_FIRST, sub {
          my $entries = shift
             or return $grp->result ();
          # stat the dir another time
          aioreq_pri $pri;
             # take the slow route if anything looks fishy
             if ($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
+               # 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 {
                $grp->result (\@dirs, \@nondirs);
             };
             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/$entry/.", sub {
                   if ($_[0] < 0) {
                      push @nondirs, $entry;
 callback with the fdatasync result code.
 If this call isn't available because your OS lacks it or it couldn't be
 detected, it will be emulated by calling C<fsync> 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<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
+C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
+C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: 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 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<fsync> on the directory fails (such as calling C<sync>).
 Passes C<0> when everything went ok, and C<-1> on error.
 =cut
    };
    $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 L<Sys::Mmap> or L<Mmap> modules for details on this, note
+that the scalar must only be modified in-place while an aio operation is
+pending on it).
+It calls the C<msync> 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<undef>, then it goes till the end of the string. The flags can be
+a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
+C<IO::AIO::MS_SYNC>.
+=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<aio_msync>, above, except for flags, which must be either
+C<0> (which reads all pages and ensures they are instantiated) or
+C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
+writing an octet from it, which dirties the page).
 =item aio_group $callback->(...)
 This is a very special aio request: Instead of doing something, it is a
 container for other aio requests, which is useful if you want to bundle
 many requests into a single, composite, request with a definite callback
 =item cancel $req
 Cancels the request, if possible. Has the effect of skipping execution
 when entering the B<execute> state and skipping calling the callback when
 entering the the B<result> state, but will leave the request otherwise
-untouched. That means that requests that currently execute will not be
+untouched (with the exception of readdir). That means that requests that
-stopped and resources held by the request will not be freed prematurely.
+currently execute will not be stopped and resources held by the request
+will not be freed prematurely.
 =item cb $req $callback->(...)
 Replace (or simply set) the callback registered to the request.
 Their lifetime, simplified, looks like this: when they are empty, they
 will finish very quickly. If they contain only requests that are in the
 C<done> 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
+That means after creating a group you have some time to add requests
-in the callbacks of those requests, you can add further requests to the
+(precisely before the callback has been invoked, which is only done within
-group. And only when all those requests have finished will the the group
+the C<poll_cb>). And in the callbacks of those requests, you can add
-itself finish.
+further requests to the group. And only when all those requests have
+finished will the the group itself finish.
 =over 4
 =item add $grp ...
 =item $grp->cancel_subs
 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
 subrequests have finished and set the groups errno to the current value
 =item feed $grp $callback->($grp)
 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
+this might starve other requests for a potentially long time. For example,
-example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
+C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
-requests, delaying any later requests for a long time.
+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
 feed callback will be called whenever there are few enough (see C<limit>,
 below) requests active in the group itself and is expected to queue more
 not impose any limits).
 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:
    # stat all files in @files, but only ever use four aio requests concurrently:
 Sets the feeder limit for the group: The feeder will be called whenever
 the group contains less than this many requests.
 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
 =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
 =over 4
 =item $fileno = IO::AIO::poll_fileno
 Return the I<request result pipe file descriptor>. This filehandle must be
-polled for reading by some mechanism outside this module (e.g. Event or
+polled for reading by some mechanism outside this module (e.g. EV, Glib,
-select, see below or the SYNOPSIS). If the pipe becomes readable you have
+select and so on, see below or the SYNOPSIS). If the pipe becomes readable
-to call C<poll_cb> to check the results.
+you have to call C<poll_cb> to check the results.
 See C<poll_cb> 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
+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
-when no events are outstanding. The amount of events processed depends on
+are outstanding. The amount of events processed depends on the settings of
-the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
+C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
 If not all requests were processed for whatever reason, the filehandle
-will still be ready when C<poll_cb> returns.
+will still be ready when C<poll_cb> 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,
               cb => \&IO::AIO::poll_cb);
 =item IO::AIO::npending
 Returns the number of requests currently in the pending state (executed,
 but not yet processed by poll_cb).
+=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<eio_sendfile_sync> function, which is like C<aio_sendfile>,
+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<posix_fadvise> function (see it's
+manpage for details). The following advice constants are
+avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
+C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
+C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
+On systems that do not implement C<posix_fadvise>, this function returns
+ENOSYS, otherwise the return value of C<posix_fadvise>.
 =back
 =cut
 Known bugs will be fixed in the next release.
 =head1 SEE ALSO
-L<Coro::AIO>.
+L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
+more natural syntax.
 =head1 AUTHOR
  Marc Lehmann <schmorp@schmorp.de>
  http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC vs. Revision 1.172 by root, Thu Jan 7 18:08:21 2010 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC vs.
Revision 1.172 by root, Thu Jan 7 18:08:21 2010 UTC