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From Randgalt <...@git.apache.org>
Subject [GitHub] zookeeper pull request #378: [ZOOKEEPER-2903] Backport of ZOOKEEPER-2901 cha...
Date Sat, 23 Sep 2017 15:07:22 GMT
GitHub user Randgalt opened a pull request:

    https://github.com/apache/zookeeper/pull/378

    [ZOOKEEPER-2903] Backport of ZOOKEEPER-2901 changes

    See https://github.com/apache/zookeeper/pull/377
    
    There was a major oversight when TTL nodes were implemented. The session ID generator
for each server is seeded with the configured Server ID in the high byte. TTL Nodes were using
the highest bit to denote a TTL node when used in the ephemeral owner. This meant that Server
IDs > 127 that created ephemeral nodes would have those nodes always considered TTL nodes
(with the TTL being essentially a random number).
    
    This PR ports these changes to the 3.5.x branch

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/Randgalt/zookeeper ZOOKEEPER-2903

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/zookeeper/pull/378.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #378
    
----
commit aa2fe9565306739d6987dcdd0fcb4aa9c032ecfc
Author: randgalt <jordan@jordanzimmerman.com>
Date:   2017-09-23T06:11:19Z

    There was a major oversight when TTL nodes were implemented. The session ID generator
for each server is seeded with the configured
    Server ID in the high byte. TTL Nodes were using the highest bit to denote a TTL node
when used in the ephemeral owner. This meant
    that Server IDs > 127 that created ephemeral nodes would have those nodes always considered
TTL nodes (with the TTL being essentially
    a random number).
    
    This PR fixes the issue by disabling TTL Nodes by default. They must now be enabled in
zoo.cfg. When TTL Nodes are enabled, the max
    Server ID changes from 255 to 254. This allows the high byte of a session ID stored in
the ephemeral owner to use 0xFF to denote
    a TTL node.

commit 63c21e4c57beff5fbb49a44f5ece864eb38016aa
Author: randgalt <jordan@jordanzimmerman.com>
Date:   2017-09-23T14:32:43Z

    Enabled ttl nodes in the example zoo.cfg as the cost of doing so is very low. Including
a comment about the different max server id

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