RE: [eclipse-incubator-e4-dev] [resources] EFS IFileTree

["Oberhuber, Martin" <Martin.Oberhuber@xxxxxxxxxxxxx>]

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

 

 

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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