[Mondrian] RolapSchema #122

Sherman Wood swood at jaspersoft.com
Tue Feb 17 18:20:20 EST 2009


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/CacheStrateg
y.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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