Ivan Andika created HDDS-16166:
----------------------------------
Summary: Clarify the allocateBlock contracts
Key: HDDS-16166
URL: https://issues.apache.org/jira/browse/HDDS-16166
Project: Apache Ozone
Issue Type: Improvement
Reporter: Ivan Andika
Assignee: Ivan Andika
This is an open discussion, need feedback.
I noticed that ScmBlockLocationProtocol allocateBlock Javadoc does not have any
guarantee on the List<AllocatedBlock> returned and when to throw exception.
This is an important API and we should clarify the contract in greater detail
so that the client and implementers know the contract deeply.
These are the discussion points
* Does the returned List<AllocateBlock> size need to be equal to the "num"
parameter?
** Currently, it does not seem to be since BlockManagerImpl#allocateBlock can
return null if there is no container and SCMBlockProtocolServer simply skip
this block
** So there is a possibility where an allocateBlock asking for 2 blocks might
return <2 (0 / 1) blocks.
** Is this a reasonable contract? Or should we throw exception if we can only
allocate blocks less than the specified "num"
*** In Ozone case, it might be fine since the BlockOutputStream would try to
call OmAllocateBlockRequest if we have less than the required block
* Does each container in AllocatedBlock in List<AllocatedBlock> definitely
reserve the "size" for client, or will there be a possibility where the
AllocatedBlock is pointing to a container that is already full?
** This is more one the space accounting part
I will document this.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
