Hi All,
I'm nearly ready to submit a patch that started with the goal of being
able to retrieve the device id and fixing FileReference>>isSymlink and
also follows Esteban's suggestion of splitting out file existence and
other attributes (which provides a performace gain). See the summary
below for a description of the changes.
The patch involves adding a new VM plugin, FileAttriubutesPlugin. To
minimise the chance of any problems along the way I'd like to submit the
patch in three steps:
1. Add the VM plugin (FileAttributesPlugin)
2. Add the code the image that allows testing of the code and plugin,
but doesn't do any integration with existing functionality.
This will allow the plugin to be tested by a few volunteers
(hopefully).
3. Add the patches that make the switch over to the new implementation.
Can someone point me to how to submit a new VM plugin? The code is
contained in a subclass of InterpreterPlugin.
I've been using this as my production environment for about 2 months now
on a linux 32 bit VM. Running the full test suite results in the same
set of test failing before and after applying the patch.
I've also ran file related tests on linux 64 bit (run the Test Runner,
select all packages with "file" as part of the name and run all the
available tests) and the full test suite on Windows 32 bit.
The summary is:
1. #isSymlink now works properly on Linux (and it should also work on
MacOS and BSD).
2. The list of file attributes available from FileReference now is:
#accessTime (new)
#changeTime (new)
#creationTime
#deviceId (new)
#exists
#gid (new)
#inode (new)
#isBlock (new)
#isCharacter (new)
#isDirectory
#isExecutable (new)
#isFIFO (new)
#isFile
#isReadable
#isRegular (new)
#isSocket (new)
#isSymlink (works)
#isWritable
#modificationTime
#numberOfHardLinks (new)
#permissions
#size
#targetFile (new)
#uid (new)
3. FileReference>>exists is faster than before (well, at least on my
linux laptop). This is useful as it is called quite often.
4. It is possible to retrieve symbolic link attributes, e.g. all the
attributes listed above plus the target path.
Given how similar MacOS and BSD are to linux, I assume that this will
all work without problem on those platforms (but it obviously needs to
be tested).
As implied above, the changes are all backward compatible (except
the broken #isSymlink), although a couple deserve mention:
1. Obviously #isSymlink now answers correctly (previously it would only
answer correctly for a broken link).
2. Requesting any of the attributes listed above (except #isSymlink)
will return the value of the target path. If the FileReference is to a
broken symbolic link, it will return the attributes of the symbolic
link (keeping existing behaviour).
3. The attributes of a symbolic link can be retrieved using
FileReference>>symlinkAttributes.
Overall, performance is slightly better than before. Code that
needs to access multiple attributes and is written to take advantage of
the new behaviour will see significant performance improvements.
If you've got this far and forgotten the original question :-)
Can someone point me to how to submit a new VM plugin?
Thanks,
Alistair
