Add a flagpole mechanism #19
Description
Add APIs to allow setting and retrieving the status of "flagpoles" (short multi-state properties) which are associated with a particular cluster. These need not be fully supported using all back-ends.
For the SQL back-end, the flagpole table would have the following fields:
- Cluster key
- Cluster environment
- Optional partition
- Flagpole key
- Flagpole value
Both the flagpole key and value would be varchar(16).
There should also be a command-line utility for setting and interrogating flagpole status for a cluster.
For example, this mechanism would allow processing in a cluster to be suspended temporarily without terminating processes such that a data migration procedure can be completed without triggering deadlocks.
Depends upon #11