Mark Hindess wrote:
In message <4a6844da.7040...@googlemail.com>, Oliver Deakin writes:
Tim Ellison wrote:
On 23/Jul/2009 09:43, Sean Qiu wrote:
Do we really need this big change?
There are so many "duplicated" xml files whose original goal is to
achieve modularity.
So each component can be developed and tested separately.
I guess that's the reason that we got so many build scripts on each
modules of classlib.
(It is another story whether they worked as we expected)
I prefer to keep jdktools and classlib separately, it sounds more
natural to me.
My gut feeling is also to keep the class library and jdktools
separated, but I'll admit that it is only a gut feeling and not
something I can defend technically.
If it really does make life easier for build then it is something I
could learn to live with. I'd like to hear the arguments though.
I agree. It just feels to me like the VM and classlib are obvious
"units" and putting the additional jre/jdk tools in with either one
of them doesn't sit right.
I'm still not sure I've heard a convincing technical argument about the
current split.
I not sure I've heard a convincing technical argument not to have them
split :) A long time ago the tools were another module of classlib, and
general concensus seemed to be that they would be better organised as a
separate component to the class libraries, so they were split. I think
the rationale was simply that all the other modules were part of the
class libraries except for the "tools" module and as such it was a bit
of an odd-one-out. Separating the tools from the class libraries made
sense from a source organisation point of view rather than a technical one.
I feel sure we'd all be just as happy if the original
split had been vm and non-vm. (I really think of this split as the VM
and the frontends to the VM that users generally use and it seems quite
natural to me.)
I might argue that this is not really a convincing technical argument to
separate the VM and other components' source from each other, which at
the moment seems to result in having quite different organisation of
code between VM and classlib and different build systems (cpptasks vs.
make). I think the real reason is that separating their source into
different locations just makes organisational sense because they are
clearly separate layers of the JDK [1], and I would argue similarly for
the jdktools component.
(I think deep down Oli isn't convinced either since he recently sent
a message to the dev@ list with tags "[classlib][jdwp]" and made no
I was just demonstrating how separate classlib is from jdwp by not
mentioning it in my mail ;)
mention of anything classlib-related AFAICT. ;-)
However, I think improving the federated build so that it could be used
by those currently working with just classlib (or jdktools or vm) would
be a reasonable compromise.
If our goals are to get the jdktools
used/looked at more and to unify the build scripts as much as
possible, then I would suggest improving the federated build for wider
use.
At the moment if a contributor wants to just work on classlib, they
will probably just check out classlib trunk and build from there
copying in whichever VM they wish to use. I think it would be better
if we made the federated build the starting point for this kind of
development and improved the build targets it provides so it plays
nicely when working with individual components. For this to work
we would need to allow more control over what source gets checked
out/built/tested, so they more closely reflect the targets within the
components - here's a few examples of what I was thinking of (names
like hy.component are just suggestions, not really important):
"ant -Dhy.component=classlib,jdktools populate-src" - just checkout the
source for classlib and jdktools
"ant -Dhy.component=classlib rebuild-native" - just clean and build the
native code for the classlib module, and automatically populate the
built binaries under the federated target directory
"ant build-java" - build java code across all components. This target
could detect which components have been checked out, much as the
classlib build works out which modules to build automatically by
checking if build targets exists, and only build those so that
hy.component does not always need to be specified.
The above is just a rough idea of how it could be done, but I can see a
few advantages of this approach:
1) The federated build would get used more, giving us a more unified
approach to building Harmony while still allowing contributors to work
in individual areas with the same ease. This should also help remove
some of the build script duplication across components.
2) The java/javaw executables could be moved to jdktools (which makes
more sense than classlib to me) meaning that jdktools would get more
attention also.
3) The common_resources directory would work for those working on the
whole jdk and also for those just working on one or two components, as
they would both use the federated build.
4) If we ever wanted to add components (for example, split portlib into
it's own component) it would be easier managed.
5) If you started working on drlvm only and also wanted to make some
changes to classlib later on, you could just run populate-src specifying
the classlib component to check out the additional source and then carry
on working.
I like this idea. If we are going to improve the federated build can
we also:
1) Find a way to reduce coupling. Currently federated/build.xml know
too much about DRLVM - things like the "set overwrite flag to take
hythr from VM" comment.
2) Call the directories drlvm, jdktools and classlib rather than working_*.
3) Allow the choice of VM component to be overridden - default 'drlvm'.
+1 to all 3 of these.
These are just ideas at the moment, but I can see there are benefits to
this approach. Any thoughts/comments?
Perhaps we could create a new federated sandbox to work out ideas?
That sounds like a good starting point.
Regards,
Oliver
[1] http://java.sun.com/j2se/1.5.0/docs/images/j2se5.gif
Regards,
Mark.
--
Oliver Deakin
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