[Mondrian] RolapSchema #122

Matt Campbell mkambol at gmail.com
Wed Feb 18 10:14:42 EST 2009


It does certainly seem to be a vfs bug.  As a workaround, I added the
following block right after the .resolveFile().  This validates that the url
passed in matches the url of the file retrieved, and if not clears the file
from the cache and reloads.
 if ( !file.getName().getURI().equals(url)) {
            fsManager.getFilesCache().removeFile(file.getFileSystem(),
 file.getName());
            file = fsManager.resolveFile(userDir, url);
        }

Any objection to me checking in this change?  If we find a better workaround
to the vfs bug we can always drop this check.


On Tue, Feb 17, 2009 at 6:20 PM, Sherman Wood <swood at jaspersoft.com> wrote:

>  I was just going to refactor RolapSchema.load() to use
> Util.readVirtualFile() because of that identical code.
>
>
>
> The default configuration of Apache VFS we are using should be getting new
> content each time a URI is "resolved" (
> http://commons.apache.org/vfs/apidocs/org/apache/commons/vfs/CacheStrategy.html#ON_RESOLVE), which happens each time .readVirtualFile is called.
>
>
>
> I'll do some further tests, taking into account Will's comments about
> possible VFS HTTP bugs.
>
>
>
>
>
> Sherman
>
>
>
> *From:* mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
> *On Behalf Of *Matt Campbell
> *Sent:* Wednesday, February 18, 2009 6:14 AM
> *To:* Mondrian developer mailing list
> *Subject:* Re: [Mondrian] RolapSchema #122
>
>
>
> I just noticed that RolapSchema.load() uses identical code to
> Util.readVirtualFile().  It seems likely that it would have the same problem
> with cached files.
>
> On Tue, Feb 17, 2009 at 12:18 PM, Matt Campbell <mkambol at gmail.com> wrote:
>
> It looks like the parameters in the URL are ignored on the second call to
> readVirtualFile().  The unit test below shows the issue.  The URI of the
> second file returned by .readVirtualFile ends up being identical to uri1.
>
>
>
> Could you revert your change until this is fixed?
>
>
>
>  public void testReadVirtualFile() {
>
>         try {
>
>             String uri1 = "http://localhost:8088/?URI1";
>
>             String uri2 = "http://localhost:8088/?URI2";
>
>             FileObject file1 = Util.readVirtualFile(uri1);
>
>             FileObject file2 = Util.readVirtualFile(uri2);
>
>
>
>             assertEquals(file1.getName().getURI(), uri1);
>
>             assertEquals(file2.getName().getURI(), uri2);
>
>         } catch(Exception e) {
>
>              fail("Threw an exception while reading virtual file");
>
>         }
>
>     }
>
>
>
> On Mon, Feb 16, 2009 at 4:36 PM, Sherman Wood <swood at jaspersoft.com>
> wrote:
>
>
>
> Yep – that looks weird and bad. I'll look into it too.
>
>
>
> Sherman
>
>
>
> *From:* mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
> *On Behalf Of *Matt Campbell
> *Sent:* Tuesday, February 17, 2009 4:01 AM
> *To:* Mondrian developer mailing list
> *Subject:* [Mondrian] RolapSchema #122
>
>
>
> Sherman,
>
> It looks like a bug was introduced in the code which retrieves schemas from
> the Pool.  In Pool.get() there is code which first loads the schema from a
> given URL, then computes its checksum.  I've noticed that the new
> Util.readVirtualFile() method will sometimes return the content of the
> *previous* schema loaded.
>
>
>
> In the current code there is actually an extra read of the catalog--see the
> bolded section below.  It's leftover from the previous approach for loading
> the schema.  This should probably be cleaned up, but it helped me find the
> issue.  When I've traced through this code I've seen that the catalogStr
> returned by the old code (Util.readURL) is sometimes different from the
> schema returned by Util.readVirtualFile.
>
>
>
> I'm going to try to come up with a clean reproducible test case tomorrow,
> but I thought I'd pass on what I've seen in case you see something obviously
> wrong.
>
>
>
>                 try {
>
>                     if (catalogStr == null) {
>
>                        * catalogStr = Util.readURL(catalogUrl);*
>
>                         // Use VFS to get the content
>
>
>
>                         FileObject file = Util.readVirtualFile(catalogUrl);
>
>
>
>                         StringBuilder buf = new StringBuilder(1000);
>
>                         FileContent fileContent = file.getContent();
>
>                         InputStream in = fileContent.getInputStream();
>
>                         int n;
>
>                         while ((n = in.read()) != -1) {
>
>                             buf.append((char) n);
>
>                         }
>
>                      *   catalogStr = buf.toString();*
>
>                     }
>
>                     md5Bytes = encodeMD5(catalogStr);
>
>                 } catch (Exception ex) {
>
>                     // Note, can not throw an Exception from this method
>
>                     // but just to show that all is not well in Mudville
>
>                     // we print stack trace (for now - better to change
>
>                     // method signature and throw).
>
>                     ex.printStackTrace();
>
>                 }
>
>
>
> -Matt
>
>
>
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