jvmRoute as part of the Redis key prevents failover to other nodes #67
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added 4 commits
May 5, 2015 10:00
…l session id * Redis stores the id without the jvmRoute, since having it as part of the key effectively makes the session valid only on node with this jvmRoute * Customer still gets the original session id, including the jvmRoute, since this value is used for load balancing e.g. in mod_jk
* Don't just log the exception, but also include the session id being handled at the moment * Log the action we're undertaking (add/remove)
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Including the jvmRoute as part of the redis key prevents migrating the session to another node. This applies both to failover because a node dies, as well as normal round-robin load balancing.
Quoting the memcached session plugin FAQ (https://code.google.com/p/memcached-session-manager/wiki/FAQ):
This pull request modifies the key used in redis by stripping the jvmRoute from it. This way any node in the cluster can fetch the same value using the session id. Stripping the key happens both for newly generated session ids, as well as the ones coming from the customer.
This current implementation assumes that if the jvmRoute is not set, i.e. is null, then the session id is not tampered with.
The pull request contains some very basic sanity tests for the strip method, to make sure no unwarranted exceptions are thrown, and that the stripping logic works for various special cases.