O_NONBLOCK on files

[Simon Kirby <sim@netnation.com>]

I've always wondered why it's not possible to do this:

fd = open("an_actual_file",O_RDONLY);
fcntl(fd,F_SETFL,O_NONBLOCK);
r = read(fd,buf,4096);

And actually have read return -1 and errno == EWOULDBLOCK/EAGAIN if the
block requested is not already cached.

Wouldn't this be the ideal interface for daemons of all types that want
to stay single-threaded and still offer useful performance when the
working set doesn't fit in cache?  It works with sockets, so why not
with files?

I see even TUX has to have I/O worker threads to work around this
limitation, which seems a bit silly.

Simon-

[  Stormix Technologies Inc.  ][  NetNation Communications Inc. ]
[       sim@stormix.com       ][       sim@netnation.com        ]
[ Opinions expressed are not necessarily those of my employers. ]