The ICacheAffinity interface provides a collection of methods to determine
partitions from keys, and nodes from partitions.
The GetBackupPartitions() method will return all partitions for which the
given clusternode is a backup. This is handy if you want to identify backup
partitions on a node.
/// <summary>
/// Gets partition ids for which nodes of the given projection has
backup
/// ownership.
/// </summary>
/// <param name="n">Node.</param>
/// <returns>Partition ids for which given projection has backup
ownership.</returns>
int[] GetBackupPartitions(IClusterNode n);
What I would like to do is something similar, which is to identify all
backup partitions on a given clusternode which are backups of primary
partitions on another cluster node.
ie: I am running on Node A and want to know which partitions from Node B
does Node A have a backup for.
The use case here is broadly this "I broadcast a request to a topology
projection of nodes, one of which may not be available at the given time
(so won't be routed to it). The business logic on each node coordinates
processing of the request against the partitions that node owns. If that
node owns backup partitions from the node that is not available, it should
also process those partitions to provide the correct result".
I know Ignite will do this for me if I provide a vector of keys to an
affinity based call method (and we do have other request paths that do
similar things), however that's not practical in this particular example
for other reasons (eg: a key vector representation of the request could be
truly large), so we need to address this in the request processing
application logic itself.
We provide our own affinity function for the caches involved, so can
probably build these vectors at that time, but they would not be exposable
through the ICacheAffinity interface.
The MapPartitionToPrimaryAndBackups(int part) looks like it would provide
the required information, but would need to be called for every partition
in the cache, which feels like it might be slow.
Thoughts?
Thanks,
Raymond.
--
<http://www.trimble.com/>
Raymond Wilson
Solution Architect, Civil Construction Software Systems (CCSS)
11 Birmingham Drive | Christchurch, New Zealand
[email protected]
<https://worksos.trimble.com/?utm_source=Trimble&utm_medium=emailsign&utm_campaign=Launch>
