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From "Rick Post (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-145) RAFContainer readPage method is not thread safe
Date Sun, 13 Feb 2005 01:11:11 GMT
RAFContainer readPage method is not thread safe
-----------------------------------------------

         Key: DERBY-145
         URL: http://issues.apache.org/jira/browse/DERBY-145
     Project: Derby
        Type: Bug
  Components: Store  
    Versions: 10.0.2.1    
 Environment: N/A
    Reporter: Rick Post
    Priority: Minor


readPage method comment says 'thread safe and has a synchronized block.

But 'pageOffset' computation occurs outside the sync block as does decryption.

This allows the (remote?) possibility of part of the operation(s) being performed using the
wrong pageNumber or pageData.

Fix - synchronize the method rather than the block

	/**
		Read a page into the supplied array.

		<BR> MT - thread safe
		@exception IOException exception reading page
		@exception StandardException Standard Cloudscape error policy
	*/
	protected void readPage(long pageNumber, byte[] pageData)
		 throws IOException, StandardException
	{
		if (SanityManager.DEBUG) {
			SanityManager.ASSERT(!getCommittedDropState());
		}

		long pageOffset = pageNumber * pageSize;

		synchronized (this) {

			fileData.seek(pageOffset);

			fileData.readFully(pageData, 0, pageSize);
		}

		if (dataFactory.databaseEncrypted() &&
			pageNumber != FIRST_ALLOC_PAGE_NUMBER)
		{
			decryptPage(pageData, pageSize);
		}
	}


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