[
Date Prev][
Date Next][
Thread Prev][
Thread Next][
Date Index][
Thread Index]
[
List Home]
|
RE: [eclipse-incubator-e4-dev] [resources] EFS IFileTree
|
The advantage of the Directory Stream approach is that
clients can
see / work on intermediate results before the traversal is
complete,
and they can cancel the Stream retrieval if the
intermediate
results don't match their expectations.
I
agree that programmatic approaches like visitors or
arbitrary
coded
filters are problematic when the receiver of the query
is
remote (Java does support things like remote object
execution,
but
not all server-sides support Java...and local evaluation of
the
filter might not always be a good fallback). LDAP filters
might
be an interesting thing to explore, I haven't heard
about
these
before but anything Standard seems like a good thing
to
look at.
Here
is a different idea that might also work:
*
Initiate
Cheers,
--
Martin Oberhuber, Senior Member of Technical
Staff, Wind River
Target Management Project
Lead, DSDP PMC Member
IFileTree doesn't have a depth
because it was really intended to optimize the DEPTH_INFINITE case. For
DEPTH_ZERO or DEPTH_ONE, it doesn't provide much advantage. I agree though
that it could be interesting to support different scoping to pick up smaller
subtrees, or to have some termination condition. The purpose was really to cut
down on round-trips, so I'm not sure you'd get the same effect with a visitor
or directory stream approach. Perhaps filters could be passed in a serialized
form (like an LDAP filter), so that it can be interpreted on the machine where
the file system lives, to avoid passing unnecessary data over the wire.
John
"Oberhuber, Martin"
<Martin.Oberhuber@xxxxxxxxxxxxx>
Sent by:
eclipse-incubator-e4-dev-bounces@xxxxxxxxxxx
10/20/2008 12:49 PM
|
Please respond
to
E4 developer list
<eclipse-incubator-e4-dev@xxxxxxxxxxx> |
|
|
To
| "E4 developer list"
<eclipse-incubator-e4-dev@xxxxxxxxxxx>
|
|
cc
|
|
|
Subject
| RE: [eclipse-incubator-e4-dev]
[resources] EFS IFileTree |
|
Hi John,
One disadvantage of the IFileTree today is that the file tree to
be
returned must terminate at some point,
and not the slightest
amount of information
is returned if it does not terminate.
This makes it unusable for file systems that can
be endless
(like the Internet), or even
very very large with the user only
being
interested in parts of the file tree. Even refreshLocal
performs a breadth-first-search and can be limited by
the
depth to visit. fetchFileTree() does
not support that.
One option for improving this situation could be if the
fetchFileTree() method would not return a snapshot
like
the IFileTree, but rather return a
Stream of IFileStore / IFileInfo
objects
that the client can cancel at any time. A
breadth-first-search algorithm for returning these nodes might
be preferred, though I'd also see some potential
for allowing
arbitrary ordering of returned
nodes with some concept of
allowing a node
to be "incomplete" e.g. a folder node with
not all children returned yet.
In JSR 203, the Path#newDirectoryStream()
[1] and
Files#walkFileTree() [2] methods go in this direction.
[1] http://openjdk.java.net/projects/nio/javadoc/java/nio/file/Path.html#newDirectoryStream(java.nio.file.DirectoryStream.Filter)
[2] http://openjdk.java.net/projects/nio/javadoc/java/nio/file/Files.html#walkFileTree(java.nio.file.Path,%20java.nio.file.FileVisitor)
Cheers,
--
Martin Oberhuber, Senior Member of Technical Staff, Wind River
Target Management Project Lead, DSDP PMC Member
http://www.eclipse.org/dsdp/tm
From:
eclipse-incubator-e4-dev-bounces@xxxxxxxxxxx
[mailto:eclipse-incubator-e4-dev-bounces@xxxxxxxxxxx] On Behalf Of John
Arthorne
Sent: Friday, October 17, 2008 7:40 PM
To: E4
developer list
Subject: [eclipse-incubator-e4-dev] [resources] EFS
IFileTree
I
forgot to mention this during the meeting, so I just wanted to mention a
little know EFS interface called IFileTree. The idea of this interface was to
allow for batched interaction with an entire file sub-tree. This prevents the
large number of round-trips needed when a client needs to walk over an entire
subtree of a slow/remote file system. It allows you to get a snapshot of an
entire remote tree state in a single round-trip. In some experiments we did
back in the day, this dramatically sped up certain operations like
refreshLocal over a high latency remote tree. I mention it only because it's
probably an under-exploited concept that could perhaps be expanded upon to
improve performance in remote resource scenarios. I could imagine expanding
the idea to allow a client to queue up a whole batch of file changes, that
could be fired off in a single round-trip to the remote system for
processing.
John_______________________________________________
eclipse-incubator-e4-dev
mailing
list
eclipse-incubator-e4-dev@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/eclipse-incubator-e4-dev
