using the sendfile system call on Darwin
glewis at eyesbeyond.com
Sun Feb 21 16:47:37 PST 2010
On Fri, Feb 19, 2010 at 01:07:35PM -0800, Michael Allman wrote:
> Ok, I have a patch. How do I submit it?
Sending it to the list for review (either directly or by putting up a URL
people can see it at) is a good first step :).
> On Wed, 27 Jan 2010, Greg Lewis wrote:
> > On Tue, Jan 26, 2010 at 01:33:06AM -0800, Michael Allman wrote:
> >> I would like to update jdk/src/solaris/native/sun/nio/ch/FileChannelImpl.c
> >> so that the Java_sun_nio_ch_FileChannelImpl_transferTo0 function calls the
> >> sendfile system call on Darwin. I have a few questions:
> >> 1. Is there a cpp #define for Darwin? If not, how do I tell cpp whether
> >> the system is Darwin or not?
> > The rest of the code uses
> > #ifdef __APPLE__
> >> 2. Are there tests that exercise
> >> Java_sun_nio_ch_FileChannelImpl_transferTo0 or the java method
> >> FileChannel.transferTo?
> > Some of the tests in jdk/test/java/nio/channels/FileChannel/ may be useful,
> > I haven't looked them over though.
> >> 3. Why doesn't the existing BSD code just return IOS_UNSUPPORTED? For
> >> instance, look at lines 223 and 224. If there's no sendfile function on
> >> Solaris, the function just returns IOS_UNSUPPORTED. The caller handles
> >> that return value gracefully. The existing BSD code looks needlessly
> >> complex to me.
> > All of the BSDs have sendfile, its just limited to only sending the file to
> > a stream socket rather than any file descriptor, which Solaris and Linux
> > allow. It's fairly easy to implement code that will do that though, so
> > that's what was done rather than throwing errors when a non-socket file
> > descriptor was used.
> > Note that MacOS X seems to have the same limitations as all the other BSDs
> > in terms of what type of file descriptor can be used as the destination:
> > http://developer.apple.com/Mac/library/documentation/Darwin/Reference/ManPages/man2/sendfile.2.html
> > If NIO in general interests you, then a project we really need someone to
> > work on is porting NIO2 to BSD. None of the BSDs have the epoll mechanism
> > used on Linux or whatever Solaris uses (which I can't recall off the top of
> > my head right now). The suggestion is to use kqueue(2) on BSD.
> > --
> > Greg Lewis Email : glewis at eyesbeyond.com
> > Eyes Beyond Web : http://www.eyesbeyond.com
> > Information Technology FreeBSD : glewis at FreeBSD.org
Greg Lewis Email : glewis at eyesbeyond.com
Eyes Beyond Web : http://www.eyesbeyond.com
Information Technology FreeBSD : glewis at FreeBSD.org
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