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Michael McCandless commented on LUCENE-2316: -------------------------------------------- I don't think Lucene relies on file length; we do use it for diagnostics/logging (eg IW's infoStream). Hmm I guess we do use it for merging purposes (LogByteSizeMergePolicy), where we try to merge roughly similarly sized (by net size in bytes) segments. I would rather not increase our reliance on it (eg LUCENE-2373 proposes to do so) -- it's a piece of metadata that is sometimes (eg over NFS) less reliable than file contents. The less we rely on from the filesystem the more robust/portable Lucene will be... Net/net I think we should keep the method, but restrict our use of it. I do think we should move to throwing FNFE if the file does not exist... though I think a break in back compat may be OK, here? (Vs do the new method/deprecated/abstract approach). > Define clear semantics for Directory.fileLength > ----------------------------------------------- > > Key: LUCENE-2316 > URL: https://issues.apache.org/jira/browse/LUCENE-2316 > Project: Lucene - Java > Issue Type: Improvement > Components: Index > Reporter: Shai Erera > Priority: Minor > Fix For: 3.1 > > > On this thread: > http://mail-archives.apache.org/mod_mbox/lucene-java-dev/201003.mbox/%3c126142c1003121525v24499625u1589bbef4c079...@mail.gmail.com%3e > it was mentioned that Directory's fileLength behavior is not consistent > between Directory implementations if the given file name does not exist. > FSDirectory returns a 0 length while RAMDirectory throws FNFE. > The problem is that the semantics of fileLength() are not defined. As > proposed in the thread, we'll define the following semantics: > * Returns the length of the file denoted by <code>name</code> if the file > exists. The return value may be anything between 0 and Long.MAX_VALUE. > * Throws FileNotFoundException if the file does not exist. Note that you can > call dir.fileExists(name) if you are not sure whether the file exists or not. > For backwards we'll create a new method w/ clear semantics. Something like: > {code} > /** > * @deprecated the method will become abstract when #fileLength(name) has > been removed. > */ > public long getFileLength(String name) throws IOException { > long len = fileLength(name); > if (len == 0 && !fileExists(name)) { > throw new FileNotFoundException(name); > } > return len; > } > {code} > The first line just calls the current impl. If it throws exception for a > non-existing file, we're ok. The second line verifies whether a 0 length is > for an existing file or not and throws an exception appropriately. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: https://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira --------------------------------------------------------------------- To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org For additional commands, e-mail: java-dev-h...@lucene.apache.org