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https://issues.apache.org/jira/browse/HDFS-11026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15596667#comment-15596667
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Chris Douglas commented on HDFS-11026:
--------------------------------------
The length prefix is a
[WritableUtils|https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableUtils.java#L271]
vint. The {{expiryDate}} field should start with a negative byte, since any
valid {{expiryDate}} requires more than one byte to represent. In contrast, the
[encoding|https://developers.google.com/protocol-buffers/docs/encoding] for PB
prefixes each field with {{(field_number << 3) | wire_type}}, so as long as the
first field has a {{field_number}} less than 16, the first byte will be
positive.
[~daryn], would this be an acceptable way to distinguish the two token types?
[~anu] in HDFS-11010
[cited|https://issues.apache.org/jira/browse/HDFS-11010?focusedCommentId=15576699&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15576699]
incompatible changes in DFSClient that have already affected backwards
compatibility. Even if we adopt an approach that makes this switch redundant
(e.g., separate 2.x/3.x ports), we can undo it without affecting clients.
Thanks [~owen.omalley] (who knows too much about the internals of PB)
> Convert BlockTokenIdentifier to use Protobuf
> --------------------------------------------
>
> Key: HDFS-11026
> URL: https://issues.apache.org/jira/browse/HDFS-11026
> Project: Hadoop HDFS
> Issue Type: Task
> Components: hdfs, hdfs-client
> Affects Versions: 2.9.0, 3.0.0-alpha1
> Reporter: Ewan Higgs
> Fix For: 3.0.0-alpha2
>
> Attachments: blocktokenidentifier-protobuf.patch
>
>
> {{BlockTokenIdentifier}} currently uses a {{DataInput}}/{{DataOutput}}
> (basically a {{byte[]}}) and manual serialization to get data into and out of
> the encrypted buffer (in {{BlockKeyProto}}). Other TokenIdentifiers (e.g.
> {{ContainerTokenIdentifier}}, {{AMRMTokenIdentifier}}) use Protobuf. The
> {{BlockTokenIdenfitier}} should use Protobuf as well so it can be expanded
> more easily and will be consistent with the rest of the system.
> NB: Release of this will require a version update since 2.8.x won't be able
> to decipher {{BlockKeyProto.keyBytes}} from 2.8.y.
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