Bernhard Messer wrote:
hi,
CompoundFileReader class contains some code where i can't follow the idea behind it. Maybe somebody else can switch on the light for me, so i can see the track. There are 2 public methods which definitly don't work as expected. I know, extending Directory forces one to implement the methods, but in that particular, case the implementation is just confusing me and my be other people too.
public long fileModified(String name) throws IOException { return directory.fileModified(fileName); }
public void touchFile(String name) throws IOException { directory.touchFile(fileName); }
Looking at the implementation, both methods are working on the compound filename itself, regardless what the filename passed in has as it's value. It would be much more understandable, if these methods throw some UnsupportedOperationException. The other way is to to change them in a way, that the underlaying directory method calls will get the real filename passed in and not the compound filename itself.
Well, the reason I did it this way is because I thought this would be the least amount of disruption to the programs out there that might be using these APIs. You can't really pass the "name" into the directory since it doesn't know about these as individual files. Directoy only knows about the compound file. To implement the fileModified() fully, you could just store timestamps in the file, but then they would just the same as the timestamp on the overall file, unless there was also touchFile() support. To implement touch file, you'd have to open the file in random access and update the timestamp field of an individual file. This can certainly be done, but I didn't have a need for it. You could throw the Unsupported exception, but this could make callers have to change. Anyway, the compromise I chose was to treat a "touch" on one file as if a "touch" on all files for the segment. This works in most usages. The only time this would be a problem is if you implemented some kind of timestamp set/check that would depend on files in a segment having different timestamps. This might be important for updating segments, but since this is never done, I'm not sure this is really that useful. Do you have case in mind when this is proving to be a limitation?
Dmitry.
just a thought ;-)
bernhard
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