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" <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] 10/20/2008 12:49 PM Please respond to E4 developer list <[email protected]> To "E4 developer list" <[email protected]> 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 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 [email protected] https://dev.eclipse.org/mailman/listinfo/eclipse-incubator-e4-dev
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