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Bug 41606 - [devrev] Ability to order items in META-INF/services/ lookup
Summary: [devrev] Ability to order items in META-INF/services/ lookup
Alias: None
Product: platform
Classification: Unclassified
Component: Lookup (show other bugs)
Version: 4.x
Hardware: All All
: P2 blocker (vote)
Assignee: David Konecny
Depends on:
Blocks: 41659 41865
  Show dependency tree
Reported: 2004-04-01 17:24 UTC by Jesse Glick
Modified: 2008-12-22 18:39 UTC (History)
1 user (show)

See Also:
Exception Reporter:

implementation (13.75 KB, patch)
2004-04-30 11:36 UTC, David Konecny
Details | Diff

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Description Jesse Glick 2004-04-01 17:24:07 UTC
See thread on nbdev. Suggested syntax:

---%<--- META-INF/services/org.netbeans.api.Foo

MetaInfServicesLookup would look for these
advisory position attrs. When querying on an
interface, items with a smaller position would be
guaranteed to be returned before items with a
larger position. Items with no defined position
would be returned last.

Would be invaluable for queries, URLMapper, and so on.
Comment 1 David Konecny 2004-04-30 11:36:53 UTC
Created attachment 14638 [details]
Comment 2 David Konecny 2004-04-30 11:47:50 UTC
I'm asking for Fast Track Review. See attached diff. It contains also
unit test and documentation update.

I also measured impact of this change on performance. My testcase in
all measurements was: start IDE with clean userdir; open nb_all\ant
project; wait till all parserDBs are created; close IDE. I repeated
measurement at least twice. Here are results:
* there is no difference in the total amount of time spent in method after this change. That is, no
* if ProjectClassPathProvider registered in java/project module has
position=1 then there is significant improvement. The
ClassPath.getClassPath() method is called about 5600 times and time
spent in this method drops from 8200ms to 5300ms.
Comment 3 Jesse Glick 2004-04-30 15:53:23 UTC
MISL.insertItem looks clumsy; consider using a TreeSet and comparator

Need spec: are you allowed to position multiple impls in one file? E.g.

---%<--- META-INF/services/

What is the significance of the positioning of
ProjectClassPathProvider? Was it appearing after something slower? I
know apisupport/project installs global impls of some things (as a
provisional workaround for build products of a module going into
nbbuild) which should go after the generic multiplexing impls.
Comment 4 David Konecny 2004-05-03 13:31:28 UTC
I was considering TreeSet, but it seems to me that current impl should
be better - most of the items are not sorted and so I add them to the
end and sort only the few which has position attr.

Re. Need spec: yes, that must be documented and it is allowed - each
item can be followed by its (optional) position attr.

Re. position of ProjectClassPathProvider: I'm adding Tomas on CC. I
think it was him or you who suggested that having PCPP first in the
lookup should improve performance because most of the time you are
asking for classpath of a project source. I think Tomas said that
usually the platform/library provider is asked first what makes it
slower because it is useless call. It was just an experiment to prove
that my impl works and that it has the benefit.
Comment 5 Jesse Glick 2004-05-07 04:17:40 UTC
So I guess this is good to go tomorrow (Friday)?
Comment 6 David Konecny 2004-05-09 11:15:53 UTC
Fixed. Tomas, please update J2SE Project registrations.

Implemented in:
Checking in;
new revision: 1.142; previous revision: 1.141
Checking in api/doc/changes/apichanges.xml;
new revision: 1.198; previous revision: 1.197
Checking in api/doc/org/openide/doc-files/services-api.html;
new revision: 1.35; previous revision: 1.34
Checking in src/org/openide/util/lookup/;
new revision: 1.7; previous revision: 1.6
Checking in test/unit/src/org/openide/util/;
new revision: 1.7; previous revision: 1.6
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Checking in
initial revision: 1.1
Comment 7 David Konecny 2004-05-09 11:16:58 UTC
Comment 8 Jesse Glick 2004-05-09 16:55:42 UTC
Suggest for our queries: we use 100 as a standard position for the
simple impl in the project lookup. Probably no need to put any impls
below 100. j2seplatform can put its lib/platform impl at e.g. 150. I
will temporarily put apisupport/project's "unprojectized" stuff at 200
(though I think I know how to delete this stuff entirely later).