--- Linux-AIO/README	2005/07/08 02:43:47	1.2
+++ Linux-AIO/README	2005/07/10 01:02:51	1.4
@@ -5,10 +5,11 @@
      use Linux::AIO;
 
 DESCRIPTION
-    This module implements asynchronous i/o using the means available to
-    linux - clone. It does not hook into the POSIX aio_* functions because
-    linux does not yet support these in the kernel (and even if, it would
-    only allow aio_read and write, not open and stat).
+    This module implements asynchronous I/O using the means available to
+    Linux - clone. It does not hook into the POSIX aio_* functions because
+    Linux does not yet support these in the kernel (even as of 2.6.12, only
+    O_DIRECT files are supported) and even if, it would only allow aio_read
+    and write, not open, stat and so on.
 
     Instead, in this module a number of (non-posix) threads are started that
     execute your read/writes and signal their completion. You don't need
@@ -19,8 +20,20 @@
     when the thread calling min_parallel exits. Make sure you only ever call
     min_parallel from the same thread that loaded this module.
 
-    Although the module will work with threads, it is not reentrant, so use
-    appropriate locking yourself.
+    Although the module will work with in the presence of other threads, it
+    is not reentrant, so use appropriate locking yourself.
+
+  API NOTES
+    All the "aio_*" calls are more or less thin wrappers around the syscall
+    with the same name (sans "aio_"). The arguments are similar or
+    identical, and they all accept an additional $callback argument which
+    must be a code reference. This code reference will get called with the
+    syscall return code (e.g. most syscalls return -1 on error, unlike perl,
+    which usually delivers "false") as it's sole argument when the given
+    syscall has been executed asynchronously.
+
+    All functions that expect a filehandle will also accept a file
+    descriptor.
 
     Linux::AIO::min_parallel $nthreads
         Set the minimum number of AIO threads to $nthreads. The default is
@@ -31,6 +44,9 @@
         kernel versions will scale negatively with the number of threads
         (higher parallelity => MUCH higher latency).
 
+        Under normal circumstances you don't need to call this function, as
+        this module automatically starts a single async thread.
+
     Linux::AIO::max_parallel $nthreads
         Sets the maximum number of AIO threads to $nthreads. If more than
         the specified number of threads are currently running, kill them.
@@ -40,12 +56,16 @@
         ensure that all threads are killed and that there are no outstanding
         requests.
 
+        Under normal circumstances you don't need to call this function.
+
     $fileno = Linux::AIO::poll_fileno
         Return the *request result pipe filehandle*. This filehandle must be
         polled for reading by some mechanism outside this module (e.g. Event
         or select, see below). If the pipe becomes readable you have to call
         "poll_cb" to check the results.
 
+        See "poll_cb" for an example.
+
     Linux::AIO::poll_cb
         Process all outstanding events on the result pipe. You have to call
         this regularly. Returns the number of events processed. Returns
@@ -55,21 +75,43 @@
 
            Event->io (fd => Linux::AIO::poll_fileno,
                       poll => 'r', async => 1,
-                      cb => \&Linux::AIO::poll_cb );
+                      cb => \&Linux::AIO::poll_cb);
 
     Linux::AIO::poll_wait
         Wait till the result filehandle becomes ready for reading (simply
         does a select on the filehandle. This is useful if you want to
         synchronously wait for some requests to finish).
 
+        See "nreqs" for an example.
+
     Linux::AIO::nreqs
         Returns the number of requests currently outstanding.
 
+        Example: wait till there are no outstanding requests anymore:
+
+           Linux::AIO::poll_wait while Linux::AIO::nreqs;
+
     aio_open $pathname, $flags, $mode, $callback
         Asynchronously open or create a file and call the callback with the
         filedescriptor (NOT a perl filehandle, sorry for that, but watch
         out, this might change in the future).
 
+        The $mode argument is a bitmask. See the "Fcntl" module for a list.
+        They are the same as used in "sysopen".
+
+        Example:
+
+           aio_open "/etc/passwd", O_RDONLY, 0, sub {
+              if ($_[0] >= 0) {
+                 open my $fh, "<&$_[0]";   # create a copy for perl
+                 aio_close $_[0], sub { }; # close the aio handle
+                 print "open successful, fh is $fh\n";
+                 ...
+              } else {
+                 die "open failed: $!\n";
+              }
+           };
+
     aio_close $fh, $callback
         Asynchronously close a file and call the callback with the result
         code.
@@ -78,8 +120,30 @@
     aio_write $fh,$offset,$length, $data,$dataoffset,$callback
         Reads or writes "length" bytes from the specified "fh" and "offset"
         into the scalar given by "data" and offset "dataoffset" and calls
-        the callback without the actual number of bytes read (or "undef" on
-        error).
+        the callback without the actual number of bytes read (or -1 on
+        error, just like the syscall).
+
+        Example: Read 15 bytes at offset 7 into scalar $buffer, strating at
+        offset 0 within the scalar:
+
+           aio_read $fh, 7, 15, $buffer, 0, sub {
+              $_[0] >= 0 or die "read error: $!";
+              print "read <$buffer>\n";
+           };
+
+    aio_readahead $fh,$offset,$length, $callback
+        Asynchronously reads the specified byte range into the page cache,
+        using the "readahead" syscall.
+
+        readahead() populates the page cache with data from a file so that
+        subsequent reads from that file will not block on disk I/O. The
+        $offset argument specifies the starting point from which data is to
+        be read and $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). aio_readahead() does not
+        read beyond the end of the file. The current file offset of the file
+        is left unchanged.
 
     aio_stat $fh_or_path, $callback
     aio_lstat $fh, $callback
@@ -92,8 +156,24 @@
         silently truncated unless perl itself is compiled with large file
         support.
 
+        Example: Print the length of /etc/passwd:
+
+           aio_stat "/etc/passwd", sub {
+              $_[0] and die "stat failed: $!";
+              print "size is ", -s _, "\n";
+           };
+
     aio_unlink $pathname, $callback
-        Asynchronously unlink a file.
+        Asynchronously unlink (delete) a file and call the callback with the
+        result code.
+
+    aio_fsync $fh, $callback
+        Asynchronously call fsync on the given filehandle and call the
+        callback with the fsync result code.
+
+    aio_fdatasync $fh, $callback
+        Asynchronously call fdatasync on the given filehandle and call the
+        callback with the fdatasync result code.
 
 BUGS
     This module has been extensively tested in a large and very busy