[distcc] distcc/ccache?? cache management in a distcc environment.
Martin Pool
mbp at sourcefrog.net
Fri Jun 3 21:22:17 GMT 2005
On 3 Jun 2005, David Weeks <dkmw at earthlink.net> wrote:
> Hello again.
>
> Continuing with my earlier question, I now ask how distcc and ccache
> interact. I'm assuming at this point that the client/server
> relationship of distcc solves potential recurssion problems within
> distcc operations. In other words, I assume it is the distcc client
> that distrubutes service requests to distcc daemons, yet the daemons
> themselves NEVER distrubute service request, delivering to the compiler
> instead, and routing the compilied binary back to the requesting host.
That's correct.
> So I now wonder about the utilization of ccache. It seems to me that
> the originating host ought to first que its compile list to its own
> ccache, and where there is a miss, perhaps then que the job to a remote
> host. When the remote host receives the service request, it too should
> examine its ccache, and build only when necessary. Regardless of which
> host eventually compiles an object, the originating host ALWAYS get's
> the completed list of objects.
That might be nice, but that's not what's done at the moment. The
cache is strictly used before distribution. If you want a shared
cache (which can be a good thing) you should use a network filesystem
to sahre it.
> Is there any state management of ccache
> at this point? I don't know how ccache determines freshness, but I'm
> sure it is some comparision of source code, say a check sum? Or is it a
> make function? I don't know, but would like to.
There is a hash; see the ccache documentation as Jeremy said.
--
Martin
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