=head1 NAME IO::AIO - Asynchronous Input/Output =head1 SYNOPSIS use IO::AIO; aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { my $fh = shift or die "/etc/passwd: $!"; ... }; aio_unlink "/tmp/file", sub { }; aio_read $fh, 30000, 1024, $buffer, 0, sub { $_[0] > 0 or die "read error: $!"; }; # version 2+ has request and group objects use IO::AIO 2; aioreq_pri 4; # give next request a very high priority my $req = aio_unlink "/tmp/file", sub { }; $req->cancel; # cancel request if still in queue my $grp = aio_group sub { print "all stats done\n" }; add $grp aio_stat "..." for ...; =head1 DESCRIPTION This module implements asynchronous I/O using whatever means your 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 will still block, but you can do something else in the meantime. This is extremely useful for programs that need to stay interactive even when doing heavy I/O (GUI programs, high performance network servers etc.), but can also be used to easily do operations in parallel that are normally done sequentially, e.g. stat'ing many files, which is much faster 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 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 requests and signal their completion. You don't need thread support in perl, and the threads created by this module will not be visible to perl. In the future, this module might make use of the native aio functions available on many operating systems. However, they are often not well-supported or restricted (GNU/Linux doesn't allow them on normal files currently, for example), and they would only support aio_read and aio_write, so the remaining functionality would have to be implemented using threads anyway. Although the module will work in the presence of other (Perl-) threads, it is currently not reentrant in any way, so use appropriate locking yourself, always call C from within the same thread, or never call C (or other C functions) recursively. =head2 EXAMPLE This is a simple example that uses the EV module and loads F asynchronously: use Fcntl; use EV; use IO::AIO; # 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", IO::AIO::O_RDONLY, 0, sub { my $fh = shift or die "error while opening: $!"; # stat'ing filehandles is generally non-blocking my $size = -s $fh; # queue a request to read the file my $contents; aio_read $fh, 0, $size, $contents, 0, sub { $_[0] == $size or die "short read: $!"; close $fh; # file contents now in $contents print $contents; # exit event loop and program EV::unloop; }; }; # possibly queue up other requests, or open GUI windows, # check for sockets etc. etc. # process events as long as there are some: EV::loop; =head1 REQUEST ANATOMY AND LIFETIME Every C function creates a request. which is a C data structure not directly visible to Perl. If called in non-void context, every request function returns a Perl object representing the request. In void context, nothing is returned, which saves a bit of memory. The perl object is a fairly standard ref-to-hash object. The hash contents are not used by IO::AIO so you are free to store anything you like in it. During their existance, aio requests travel through the following states, in order: =over 4 =item ready Immediately after a request is created it is put into the ready state, waiting for a thread to execute it. =item execute A thread has accepted the request for processing and is currently executing it (e.g. blocking in read). =item pending The request has been executed and is waiting for result processing. While request submission and execution is fully asynchronous, result processing is not and relies on the perl interpreter calling C (or another function with the same effect). =item result The request results are processed synchronously by C. The C function will process all outstanding aio requests by calling their callbacks, freeing memory associated with them and managing any groups they are contained in. =item done Request has reached the end of its lifetime and holds no resources anymore (except possibly for the Perl object, but its connection to the actual aio request is severed and calling its methods will either do nothing or result in a runtime error). =back =cut package IO::AIO; use Carp (); use common::sense; use base 'Exporter'; BEGIN { our $VERSION = '4.15'; 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_msync aio_mtouch aio_mlock aio_mlockall aio_statvfs aio_wd); 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 idle_timeout nreqs nready npending nthreads 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'; require XSLoader; XSLoader::load ("IO::AIO", $VERSION); } =head1 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 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. 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. 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 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 whether it is set or not. =head2 AIO REQUEST FUNCTIONS =over 4 =item $prev_pri = aioreq_pri [$pri] Returns the priority value that would be used for the next request and, if C<$pri> is given, sets the priority for the next aio request. The default priority is C<0>, the minimum and maximum priorities are C<-4> and C<4>, respectively. Requests with higher priority will be serviced first. The priority will be reset to C<0> after each call to one of the C functions. Example: open a file with low priority, then read something from it with higher priority so the read request is serviced before other low priority open requests (potentially spamming the cache): aioreq_pri -3; aio_open ..., sub { return unless $_[0]; aioreq_pri -2; aio_read $_[0], ..., sub { ... }; }; =item aioreq_nice $pri_adjust Similar to C, but subtracts the given value from the current priority, so the effect is cumulative. =item aio_open $pathname, $flags, $mode, $callback->($fh) Asynchronously open or create a file and call the callback with a newly created filehandle for the file. The pathname passed to C must be absolute. See API NOTES, above, for an explanation. The C<$flags> argument is a bitmask. See the C module for a list. They are the same as used by C. Likewise, C<$mode> specifies the mode of the newly created file, if it didn't exist and C has been given, just like perl's C, except that it is mandatory (i.e. use C<0> if you don't create new files, and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified by the umask in effect then the request is being executed, so better never change the umask. Example: aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { if ($_[0]) { print "open successful, fh is $_[0]\n"; ... } else { die "open failed: $!\n"; } }; 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) Asynchronously close a file and call the callback with the result code. Unfortunately, you can't do this to perl. Perl I very strongly on closing the file descriptor associated with the filehandle itself. 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_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<$length> bytes from or to the specified C<$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<$data>. If C<$dataoffset> is less than zero, it will be counted from the end of C<$data>. The C<$data> scalar I be modified in any way while the request is outstanding. Modifying it can result in segfaults or World War III (if the necessary/optional hardware is installed). Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at offset C<0> within the scalar: aio_read $fh, 7, 15, $buffer, 0, sub { $_[0] > 0 or die "read error: $!"; print "read $_[0] bytes: <$buffer>\n"; }; =item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts reading at byte offset C<$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. The same C<$in_fh> works fine though, as this function does not move or use the file offset of C<$in_fh>. 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) C populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O. The C<$offset> argument specifies the starting point from which data is to be read and C<$length> specifies the number of bytes to be read. I/O is performed in whole pages, so that offset is effectively rounded down to a page boundary and bytes are read up to the next page boundary greater than or equal to (off-set+length). C does not read beyond the end of the file. The current file offset of the file is left unchanged. If that syscall doesn't exist (likely if your OS isn't Linux) it will be emulated by simply reading the data, which would have a similar effect. =item aio_stat $fh_or_path, $callback->($status) =item aio_lstat $fh, $callback->($status) Works like perl's C or C in void context. The callback will be called after the stat and the results will be available using C or C<-s _> etc... The pathname passed to C must be absolute. See API NOTES, above, for an explanation. Currently, the stats are always 64-bit-stats, i.e. instead of returning an 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 { $_[0] and die "stat failed: $!"; print "size is ", -s _, "\n"; }; =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 and $mtime being undef). Fractional times are supported if the underlying syscalls support them. When called with a pathname, uses utimes(2) if available, otherwise utime(2). If called on a file descriptor, uses futimes(2) if available, otherwise returns ENOSYS, so this is not portable. Examples: # set atime and mtime to current time (basically touch(1)): aio_utime "path", undef, undef; # set atime to current time and mtime to beginning of the epoch: aio_utime "path", time, undef; # undef==0 =item aio_chown $fh_or_path, $uid, $gid, $callback->($status) Works like perl's C function, except that C for either $uid or $gid is being interpreted as "do not change" (but -1 can also be used). Examples: # same as "chown root path" in the shell: aio_chown "path", 0, -1; # same as above: aio_chown "path", 0, undef; =item aio_truncate $fh_or_path, $offset, $callback->($status) 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. =item aio_unlink $pathname, $callback->($status) Asynchronously unlink (delete) a file and call the callback with the result code. =item aio_mknod $pathname, $mode, $dev, $callback->($status) [EXPERIMENTAL] Asynchronously create a device node (or fifo). See mknod(2). The only (POSIX-) portable way of calling this function is: 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) Asynchronously create a new link to the existing object at C<$srcpath> at the path C<$dstpath> and call the callback with the result code. =item aio_symlink $srcpath, $dstpath, $callback->($status) Asynchronously create a new symbolic link to the existing object at C<$srcpath> at the path C<$dstpath> and call the callback with the result code. =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 rename(2) and call the callback with the result code. =item aio_mkdir $pathname, $mode, $callback->($status) Asynchronously mkdir (create) a directory and call the callback with the result code. C<$mode> will be modified by the umask at the time the request is executed, so do not change your umask. =item aio_rmdir $pathname, $callback->($status) Asynchronously rmdir (delete) a directory and call the callback with the result code. =item aio_readdir $pathname, $callback->($entries) Unlike the POSIX call of the same name, C reads an entire directory (i.e. opendir + readdir + closedir). The entries will not be sorted, and will B include the C<.> and C<..> entries. 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<$type> is one of the C constants: C, C, C, C, C, C, C, C, C. C means just that: readdir does not know. If you need to know, you have to run stat yourself. Also, for speed reasons, the C<$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. =cut sub aio_load($$;$) { my ($path, undef, $cb) = @_; my $data = \$_[1]; my $pri = aioreq_pri; my $grp = aio_group $cb; aioreq_pri $pri; add $grp aio_open $path, O_RDONLY, 0, sub { my $fh = shift or return $grp->result (-1); aioreq_pri $pri; add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub { $grp->result ($_[0]); }; }; $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 a status of C<0> (ok) or C<-1> (error, see C<$!>). 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. If an error occurs, the partial destination file will be unlinked, if possible, except when setting atime, mtime, access mode and uid/gid, where errors are being ignored. =cut sub aio_copy($$;$) { my ($src, $dst, $cb) = @_; my $pri = aioreq_pri; my $grp = aio_group $cb; aioreq_pri $pri; add $grp aio_open $src, O_RDONLY, 0, sub { if (my $src_fh = $_[0]) { my @stat = stat $src_fh; # hmm, might block over nfs? aioreq_pri $pri; add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub { if (my $dst_fh = $_[0]) { aioreq_pri $pri; add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub { if ($_[0] == $stat[7]) { $grp->result (0); close $src_fh; my $ch = sub { aioreq_pri $pri; add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub { aioreq_pri $pri; add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub { aioreq_pri $pri; add $grp aio_close $dst_fh; } }; }; aioreq_pri $pri; add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub { if ($_[0] < 0 && $! == ENOSYS) { aioreq_pri $pri; add $grp aio_utime $dst, $stat[8], $stat[9], $ch; } else { $ch->(); } }; } else { $grp->result (-1); close $src_fh; close $dst_fh; aioreq $pri; add $grp aio_unlink $dst; } }; } else { $grp->result (-1); } }, } else { $grp->result (-1); } }; $grp } =item aio_move $srcpath, $dstpath, $callback->($status) Try to move the I (directories not supported as either source or destination) from C<$srcpath> to C<$dstpath> and call the callback with a status of C<0> (ok) or C<-1> (error, see C<$!>). This is a composite request that tries to rename(2) the file first; if rename fails with C, it copies the file with C and, if that is successful, unlinks the C<$srcpath>. =cut sub aio_move($$;$) { my ($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]); unless ($_[0]) { aioreq_pri $pri; add $grp aio_unlink $src; } }; } else { $grp->result ($_[0]); } }; $grp } =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 names, directories you can recurse into (directories), and ones you cannot recurse into (everything else, including symlinks to directories). C is a composite request that creates of many sub requests_ C<$maxreq> specifies the maximum number of outstanding aio requests that this function generates. If it is C<< <= 0 >>, then a suitable default will be chosen (currently 4). On error, the callback is called without arguments, otherwise it receives two array-refs with path-relative entry names. Example: aio_scandir $dir, 0, sub { my ($dirs, $nondirs) = @_; print "real directories: @$dirs\n"; print "everything else: @$nondirs\n"; }; Implementation notes. The C cannot be avoided, but C'ing every entry can. 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), 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 fortunately are the vast majority of filesystems around. It will also likely work on non-POSIX filesystems with reduced efficiency as those tend to return 0 or 1 as link counts, which disables the directory counting heuristic. =cut sub aio_scandir($$;$) { my ($path, $maxreq, $cb) = @_; my $pri = aioreq_pri; my $grp = aio_group $cb; $maxreq = 4 if $maxreq <= 0; # get a wd object aioreq_pri $pri; add $grp aio_wd $path, sub { $_[0] or return $grp->result (); my $wd = [shift, "."]; # stat once aioreq_pri $pri; 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_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 $wd, sub { my $hash2 = join ":", (stat _)[0,1,3,7,9]; 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 # for non-posix-fs's, we rely on nlink < 2 $ndirs = (stat _)[3] - 2 or return $grp->result ([], $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 $entry = shift @$entries; aioreq_pri $pri; $wd->[1] = "$entry/."; add $statgrp aio_stat $wd, sub { if ($_[0] < 0) { push @nondirs, $entry; } else { # need to check for real directory aioreq_pri $pri; $wd->[1] = $entry; add $statgrp aio_lstat $wd, sub { if (-d _) { push @dirs, $entry; unless (--$ndirs) { push @nondirs, @$entries; feed $statgrp; } } else { push @nondirs, $entry; } } } }; }; }; }; }; }; $grp } =item aio_rmtree $pathname, $callback->($status) Delete a directory tree starting (and including) C<$path>, return the status of the final C only. This is a composite request that uses C to recurse into and rmdir directories, and unlink everything else. =cut sub aio_rmtree; sub aio_rmtree($;$) { my ($path, $cb) = @_; my $pri = aioreq_pri; my $grp = aio_group $cb; 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]); }; }; (aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs; (aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs; add $grp $dirgrp; }; $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 with the fsync result code. =item aio_fdatasync $fh, $callback->($status) Asynchronously call fdatasync on the given filehandle and call the 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 instead. =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 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_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 container for other aio requests, which is useful if you want to bundle many requests into a single, composite, request with a definite callback and the ability to cancel the whole request with its subrequests. Returns an object of class L. See its documentation below for more info. Example: my $grp = aio_group sub { print "all stats done\n"; }; add $grp (aio_stat ...), (aio_stat ...), ...; =item aio_nop $callback->() This is a special request - it does nothing in itself and is only used for side effects, such as when you want to add a dummy request to a group so that finishing the requests in the group depends on executing the given code. While this request does nothing, it still goes through the execution phase and still requires a worker thread. Thus, the callback will not be executed immediately but only after other requests in the queue have entered their execution phase. This can be used to measure request latency. =item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* Mainly used for debugging and benchmarking, this aio request puts one of the request workers to sleep for the given time. While it is theoretically handy to have simple I/O scheduling requests like sleep and file handle readable/writable, the overhead this creates is immense (it blocks a thread for a long time) so do not use this function except to put your application under artificial I/O pressure. =back =head2 IO::AIO::WD - multiple working directories Your process only has one current working directory, which is used by all threads. This makes it hard to use relative paths (some other component could call C at any time, and it is hard to control when the path will be used by IO::AIO). One solution for this is to always use absolute paths. This usually works, but can be quite slow (the kernel has to walk the whole path on every access), and can also be a hassle to implement. Newer POSIX systems have a number of functions (openat, fdopendir, futimensat and so on) that make it possible to specify working directories per operation. For portability, and because the clowns who "designed", or shall I write, perpetrated this new interface were obviously half-drunk, this abstraction cannot be perfect, though. IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD object. This object stores the canonicalised, absolute version of the path, and on systems that allow it, also a directory file descriptor. Everywhere where a pathname is accepted by IO::AIO (e.g. in C or C), one can specify an array reference with an IO::AIO::WD object and a pathname instead (or the IO::AIO::WD object alone, which gets interpreted as C<[$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 called in non-void context. =over 4 =item cancel $req 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 (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->(...) Replace (or simply set) the callback registered to the request. =back =head2 IO::AIO::GRP CLASS This class is a subclass of L, so all its methods apply to objects of this class, too. A IO::AIO::GRP object is a special request that can contain multiple other aio requests. You create one by calling the C constructing function with a callback that will be called when all contained requests have entered the C state: my $grp = aio_group sub { print "all requests are done\n"; }; You add requests by calling the C method with one or more C objects: $grp->add (aio_unlink "..."); add $grp aio_stat "...", sub { $_[0] or return $grp->result ("error"); # add another request dynamically, if first succeeded add $grp aio_open "...", sub { $grp->result ("ok"); }; }; This makes it very easy to create composite requests (see the source of C for an application) that work and feel like simple requests. =over 4 =item * The IO::AIO::GRP objects will be cleaned up during calls to C, just like any other request. =item * They can be canceled like any other request. Canceling will cancel not only the request itself, but also all requests it contains. =item * They can also can also be added to other IO::AIO::GRP objects. =item * You must not add requests to a group from within the group callback (or any later time). =back 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 state, they will also finish. Otherwise they will continue to exist. 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 =item add $grp ... =item $grp->add (...) Add one or more requests to the group. Any type of L can be added, including other groups, as long as you do not create circular dependencies. Returns all its arguments. =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 of errno (just like calling C without an error number). By default, no argument will be passed and errno is zero. =item $grp->errno ([$errno]) Sets the group errno value to C<$errno>, or the current value of errno when the argument is missing. Every aio request has an associated errno value that is restored when the callback is invoked. This method lets you change this value from its default (0). Calling C will also set errno, so make sure you either set C<$!> before the call to C, or call c after it. =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 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 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, below) requests active in the group itself and is expected to queue more requests. The feed callback can queue as many requests as it likes (i.e. C does 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> 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: my $grp = aio_group sub { print "finished\n" }; limit $grp 4; feed $grp sub { my $file = pop @files or return; add $grp aio_stat $file, sub { ... }; }; =item limit $grp $num 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. This filehandle must be 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 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, 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 (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