There's also place for alternate Directories, which can throw readable-loggable exceptions without waiting for nio2.
On Fri, Apr 23, 2010 at 14:20, Michael McCandless <[email protected]> wrote: > Deletion can conceivably fail for a number of interesting reasons :) > File doesn't exist, permission is denied, file system corruption, some > kind of temporary resource starvation problem, etc... > > And actually it looks like Java 7 (nio.2) has moved to throwing an > IOException (Path.delete) instead of returning a boolean > (File.delete): > > http://www.baptiste-wicht.com/2010/03/nio-2-path-api-java-7/ > > If only nio.2 exposed some way to madvise/posix_fadvise so segment > merging wouldn't obliterate the IO cache... > > Mike > > On Thu, Apr 22, 2010 at 11:45 PM, Shai Erera <[email protected]> wrote: >> I understand your point Mike, but I don't think that returning a >> boolean will make the Dir API poor. Today boolean is as descriptive as >> an exception, only much more efficient to handle - given the current >> Dir impls in Lucene and that we don't think there are many impls out >> there … >> >> Also, I think the Java API makes sense - there cannot be too many >> reasons for failing to delete a file. So runtime SecurityException >> (which must be rarerly thrown) + boolean seems fine to me. >> >> But really, if you don't think we should change the API, let's drop it. >> >> Shai >> >> On Thursday, April 22, 2010, Michael McCandless >> <[email protected]> wrote: >>> Actually they both seem consistent today? Ie, Directory.deleteFile >>> returns nothing (void) and throws an IOE if the delete fails. >>> >>> Both FSDir and RAMDir throw IOE when the delete fails (yes, RAMDir >>> throws FNFE, but that's an IOE subclass). >>> >>> Just because the java API is poor (returns true or false instead of >>> throwing specific IOEs) doesn't mean we should make our Directory API >>> poor? >>> >>> And, how IFD deals with files that refuse to be deleted, seems >>> orthogonal to how Directory.deleteFile conveys the fact that the file >>> cannot be deleted... >>> >>> Mike >>> >>> On Wed, Apr 21, 2010 at 1:02 PM, Shai Erera <[email protected]> wrote: >>>> I think today it's simply inconsistent - RAMDir throws FNFE if the file >>>> does >>>> not exist (and no other IOE) while FSDir throws IOE for whatever reason >>>> File.delete() returned false (not adding any information as to the cause). >>>> FSDir cannot do much more than what it does, because File.delete() does not >>>> throw any exception, except for the runtime SecurityException, which is >>>> ignored (propagated) by FSDir. I've never seen a SecurityException thrown >>>> by >>>> File.delete() ... >>>> >>>> And one can still (like IFD does) call dir.fileExist in case delete >>>> returned >>>> false to differentiate between "file exists and could not be deleted" to >>>> "file does not exist". As one can do w/ File. And then throw a more >>>> descriptive exception. >>>> >>>> Also, I think that given all the current impls don't add any (concrete) >>>> information as to why the file was not deleted, I think we should define >>>> the >>>> proper semantics: "Returns true iff the file was successfully deleted. If >>>> false is returned, it is advised to call #fileExists(String) to >>>> differentiate between a delete failure because the file does not exist, to >>>> another failure". >>>> >>>> We can keep the 'throws IOException' for "whatever other bad things >>>> happened", but I'd hate to do that, especially as there are probably not so >>>> many Directory implementations out there which can return more meaningful >>>> info then true/false. And if we keep the IOE, I think we should do >>>> something >>>> in IFD rather than swallow the exception and retry over if the file exists >>>> ... currently the code assumes the exception is temporary, which may not be >>>> the case w/ external Dir impls. And if we fix that ... well we need to fix >>>> 'deletePendingFiles' as well ... this becomes a mess. >>>> >>>> What do you think? >>>> >>>> Shai >>>> >>>> On Wed, Apr 21, 2010 at 7:01 PM, Michael McCandless >>>> <[email protected]> wrote: >>>>> >>>>> I agree clarity is important so we should tighten up this spec. >>>>> >>>>> But, don't we potentially lose information if we just return true or >>>>> false? (Ie why the deletion failed). Failing because of FNFE vs a >>>>> "permission denied" or filesystem corruption are very different. But, >>>>> then, our hands are tied anyway since File.delete returns boolean... >>>>> so maybe we should simply return a boolean...? >>>>> >>>>> Mike >>>>> >>>>> On Wed, Apr 21, 2010 at 11:32 AM, Shai Erera <[email protected]> wrote: >>>>> > Hi >>>>> > >>>>> > While working on LUCENE-2402, I've noticed what I think is a confusing >>>>> > behavior of Dir.deleteFile. Its signature declares throwing an >>>>> > IOException, >>>>> > but w/ no documentation to when and why will this be thrown. And then of >>>>> > course there are the two different implementations by FSDir and RAMDir: >>>>> > FSDir throws an IOException if File.delete() returns false while RAMDir >>>>> > throws FNFE if the file does not exist. >>>>> > In either case, an IOE is not thrown from the lower-level API (File in >>>>> > FSDir >>>>> > case). >>>>> > >>>>> > Then, IFD.deleteFile declares "throws IOException", but never really >>>>> > throws >>>>> > it. Instead, it calls directory.deleteFile(), catches IOE, and calls >>>>> > dir.fileExists. If the latter returns true it adds the file to the list >>>>> > of >>>>> > pending to delete files, otherwise simply ignores the exception (!?). >>>>> > >>>>> > My feeling is that this exception should not be declared on Directory, >>>>> > but >>>>> > rather have deleteFile return true or false (like Java's File). In both >>>>> > current implementations, it's not a real IO error, and if there is any >>>>> > custom Dir impl out there, which really throws IOE, then IFD clearly >>>>> > ignores >>>>> > it, and will try to delete the file again next time. >>>>> > >>>>> > So it's more that Dir.deleteFile is confusing, than IFD is broken. And I >>>>> > think clarity is important. >>>>> > >>>>> > What do you think? >>>>> > >>> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [email protected] >> For additional commands, e-mail: [email protected] >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > > -- Kirill Zakharenko/Кирилл Захаренко ([email protected]) Home / Mobile: +7 (495) 683-567-4 / +7 (903) 5-888-423 ICQ: 104465785 --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
