[ViewVC] Diff of: cvs/IO-AIO/README

Comparing IO-AIO/README (file contents):
Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs.
Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC

     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
+    nonblocking operation (again, sockets, pipes etc.) is very inefficient.
-    or might not work (aio_read fails on sockets/pipes/fifos). Use an event
-    loop for that (such as the Event module): IO::AIO will naturally fit
+    Use an event loop for that (such as the Event module): IO::AIO will
-    into such an event loop itself.
+    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
     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 "poll_cb" from within the same thread, or
+    yourself, always call "poll_cb" from within the same thread, or never
-    never call "poll_cb" (or other "aio_" functions) recursively.
+    call "poll_cb" (or other "aio_" functions) recursively.
   EXAMPLE
     This is a simple example that uses the Event module and loads
     /etc/passwd asynchronously:
               }
            };
     aio_close $fh, $callback->($status)
         Asynchronously close a file and call the callback with the result
-        code. *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 "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
+        Unfortunately, you can't do this to perl. Perl *insists* very
-        therefore best to avoid this function.
+        strongly on closing the file descriptor associated with the
+        filehandle itself. Here is what aio_close will try:
+           1. dup()licate the fd
+           2. asynchronously close() the duplicated fd
+           3. dup()licate the fd once more
+           4. let perl close() the filehandle
+           5. asynchronously close the duplicated fd
+        The idea is that the first close() flushes stuff to disk that
+        closing an fd will flush, so when perl closes the fd, nothing much
+        will need to be flushed. The second async. close() will then flush
+        stuff to disk that closing the last fd to the file will flush.
+        Just FYI, SuSv3 has this to say on close:
+           All outstanding record locks owned by the process on the file
+           associated with the file descriptor shall be removed.
+           If fildes refers to a socket, close() shall cause the socket to be
+           destroyed. ... close() shall block for up to the current linger
+           interval until all data is transmitted.
+           [this actually sounds like a specification bug, but who knows]
+        And at least Linux additionally actually flushes stuff on every
+        close, even when the file itself is still open.
+        Sounds enourmously inefficient and complicated? Yes... please show
+        me how to nuke perl's fd out of existence...
     aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
     aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
-        Reads or writes "length" bytes from the specified "fh" and "offset"
+        Reads or writes $length bytes from the specified $fh and $offset
-        into the scalar given by "data" and offset "dataoffset" and calls
+        into the scalar given by $data and offset $dataoffset and calls the
-        the callback without the actual number of bytes read (or -1 on
+        callback without the actual number of bytes read (or -1 on error,
-        error, just like the syscall).
+        just like the syscall).
+        If $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 $length is undefined in "aio_write", use the remaining length of
+        $data.
+        If $dataoffset is less than zero, it will be counted from the end of
+        $data.
         The $data scalar *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
-        necessary/optional hardware is installed).
+        III (if the necessary/optional hardware is installed).
         Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
         offset 0 within the scalar:
            aio_read $fh, 7, 15, $buffer, 0, sub {
            aio_stat "/etc/passwd", sub {
               $_[0] and die "stat failed: $!";
               print "size is ", -s _, "\n";
            };
+    aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
+        Works like perl's "utime" 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
+    aio_chown $fh_or_path, $uid, $gid, $callback->($status)
+        Works like perl's "chown" function, except that "undef" 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;
+    aio_truncate $fh_or_path, $offset, $callback->($status)
+        Works like truncate(2) or ftruncate(2).
+    aio_chmod $fh_or_path, $mode, $callback->($status)
+        Works like perl's "chmod" function.
     aio_unlink $pathname, $callback->($status)
         Asynchronously unlink (delete) a file and call the callback with the
         result code.
     aio_mknod $path, $mode, $dev, $callback->($status)
     $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
         This is a very bad function to use in interactive programs because
         it blocks, and a bad way to reduce concurrency because it is
         inexact: Better use an "aio_group" together with a feed callback.
-        Sets the maximum number of outstanding requests to $nreqs. If you to
+        Sets the maximum number of outstanding requests to $nreqs. If you do
         queue up more than this number of requests, the next call to the
         "poll_cb" (and "poll_some" and other functions calling "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
     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/README (file contents): Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs. Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC

Diff Legend

Comparing IO-AIO/README (file contents):
Revision 1.23 by root, Mon Jan 22 15:59:52 2007 UTC vs.
Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC