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Date: Thu, 1 Nov 2012 12:19:15 +0000 (UTC)
From: "Christoph Engelbert (JIRA)" <jira@apache.org>
To: directmemory-dev@incubator.apache.org
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Subject: [jira] [Commented] (DIRECTMEMORY-49) MemoryManagerService.update
 does not reuse the same pointer
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    [ https://issues.apache.org/jira/browse/DIRECTMEMORY-49?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13488633#comment-13488633 ] 

Christoph Engelbert commented on DIRECTMEMORY-49:
-------------------------------------------------

Added if-clause in AbstractMemoryManager::update to see if the currently allocated pointer has bigger or equals capacity to the length of the new payload, in this case the pointer will be reused (revision 1404554)
                
> MemoryManagerService.update does not reuse the same pointer
> -----------------------------------------------------------
>
>                 Key: DIRECTMEMORY-49
>                 URL: https://issues.apache.org/jira/browse/DIRECTMEMORY-49
>             Project: Apache DirectMemory
>          Issue Type: Bug
>            Reporter: Benoit Perroud
>            Assignee: Christoph Engelbert
>            Priority: Minor
>
> MemoryManagerService.update actually free and store again the payload, which leads to another pointer allocation. This is fine in lots of case, but when the buffer is full, we still want the update to succeed.
> Moreover, update should throw an exception (BufferOverFlowException for example) when the new payload data is bigger than the previous.
> Considering the following test, where I allocate just enough space for 1 object, I store it, and then want to update it content. I could hope this use case succeed, but it's actually not the case
> {code}
> @Test
> public void testOffHeapMemoryBufferUpdate() {
> 		
> 	final int NUMBER_OF_OBJECTS = 1;
> 	final int BUFFER_SIZE = NUMBER_OF_OBJECTS * 4; // allocate 4 bytes
> 	
> 	final OffHeapMemoryBuffer offHeapMemoryBuffer = OffHeapMemoryBufferImpl.createNew(BUFFER_SIZE);
>         // generate 4 random bytes, store, read back and assert
> 	final byte[] payload = generateRandomPayload(4);
> 	final Pointer pointer = offHeapMemoryBuffer.store(payload);
> 	Assert.assertNotNull(pointer);
> 	Assert.assertEquals(new String(payload), new String(offHeapMemoryBuffer.retrieve(pointer)));
> 	
>         // generate another payload, update it, read it and assert.
> 	byte[] otherPayload = generateRandomPayload(4);
> 	final Pointer otherPointer = offHeapMemoryBuffer.update(pointer, otherPayload);
> 	Assert.assertNotNull(otherPointer);
> 	Assert.assertEquals(new String(otherPayload), new String(offHeapMemoryBuffer.retrieve(otherPointer)));
> }
> {code}

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