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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.106 by root, Fri Jun 1 05:51:21 2007 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC

 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
+While most of this works on all types of file descriptors (for
-sockets), using these functions on file descriptors that support
+example sockets), using these functions on file descriptors that
-nonblocking operation (again, sockets, pipes etc.) is very inefficient or
+support nonblocking operation (again, sockets, pipes etc.) is very
-might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
+inefficient. Use an event loop for that (such as the L<Event|Event>
-for that (such as the L<Event|Event> module): IO::AIO will naturally fit
+module): IO::AIO will naturally fit into such an event loop itself.
-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
 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 with in the presence of other (Perl-)
+Although the module will work in the presence of other (Perl-) threads,
-threads, it is currently not reentrant in any way, so use appropriate
+it is currently not reentrant in any way, so use appropriate locking
-locking yourself, always call C<poll_cb> from within the same thread, or
+yourself, always call C<poll_cb> from within the same thread, or never
-never call C<poll_cb> (or other C<aio_> functions) recursively.
+call C<poll_cb> (or other C<aio_> functions) recursively.
 =head2 EXAMPLE
 This is a simple example that uses the Event module and loads
 F</etc/passwd> asynchronously:
 use strict 'vars';
 use base 'Exporter';
 BEGIN {
-   our $VERSION = '2.4';
+   our $VERSION = '2.5';
    our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
                      aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
                      aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
                      aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
-                     aio_chown aio_chmod aio_utime);
+                     aio_chown aio_chmod aio_utime aio_truncate);
    our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
    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);
 =item aio_close $fh, $callback->($status)
 Asynchronously close a file and call the callback with the result
-code. I<WARNING:> although accepted, you should not pass in a perl
+code.
-filehandle here, as perl will likely close the file descriptor another
-time when the filehandle is destroyed. Normally, you can safely call perls
-C<close> or just let filehandles go out of scope.
-This is supposed to be a bug in the API, so that might change. It's
+Unlike the other functions operating on files, this function uses the
-therefore best to avoid this function.
+PerlIO layer to close the filehandle. The reason is that the PerlIO API
+insists on closing the underlying fd itself, no matter what, and doesn't
+allow modifications to the fd. Unfortunately, it is not clear that you can
+call PerlIO from different threads (actually, its quite clear that this
+won't work in some cases), so while it likely works perfectly with simple
+file handles (such as the ones created by C<aio_open>) it might fail in
+interesting ways for others.
+Having said that, aio_close tries to clean up the filehandle as much as
+possible before handing it to an io thread, and generally does 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>
+Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
-into the scalar given by C<data> and offset C<dataoffset> and calls the
+into the scalar given by C<$data> and offset C<$dataoffset> and calls the
 callback without the actual number of bytes read (or -1 on error, just
 like the syscall).
+If C<$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<$dataoffset> is less than zero, it will be counted from the end of
+C<$data>.
 The C<$data> scalar I<MUST NOT> be modified in any way while the request
-is outstanding. Modifying it can result in segfaults or WW3 (if the
+is outstanding. Modifying it can result in segfaults or World War III (if
-necessary/optional hardware is installed).
+the necessary/optional hardware is installed).
 Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
 offset C<0> within the scalar:
    aio_read $fh, 7, 15, $buffer, 0, sub {
 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:
+   # 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
    # 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_chmod $fh_or_path, $mode, $callback->($status)
 Works like perl's C<chmod> function.
 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<aio_group> together with a feed callback.
 Sets the maximum number of outstanding requests to C<$nreqs>. If you
-to queue up more than this number of requests, the next call to the
+do queue up more than this number of requests, the next call to the
 C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
 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.
 but not yet processed by poll_cb).
 =back
 =cut
-# support function to convert a fd into a perl filehandle
-sub _fd2fh {
-   return undef if $_[0] < 0;
-   # try to generate nice filehandles
-   my $sym = "IO::AIO::fd#$_[0]";
-   local *$sym;
-   open *$sym, "+<&=$_[0]"      # usually works under any unix
-      or open *$sym, "<&=$_[0]" # cygwin needs this
-      or open *$sym, ">&=$_[0]" # or this
-      or return undef;
-   *$sym
-}
 min_parallel 8;
 END { flush }
 bytes of memory. In addition, stat requests need a stat buffer (possibly
 a few hundred bytes), readdir requires a result buffer and so on. Perl
 scalars and other data passed into aio requests will also be locked and
 will consume memory till the request has entered the done state.
-This is now awfully much, so queuing lots of requests is not usually a
+This is not awfully much, so queuing lots of requests is not usually a
 problem.
 Per-thread usage:
 In the execution phase, some aio requests require more memory for

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.106 by root, Fri Jun 1 05:51:21 2007 UTC vs. Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.106 by root, Fri Jun 1 05:51:21 2007 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC