CircuitSwitch might cause too many Deadlock

[makicamel]

CircuitSwitch.run and CircuitSwitch.report increment run_count and report_count when they are called.
If many method calls pour into, CircuitSwitch tries writing to the single record frequently.
This might cause too many Deadlock and increase cpu load.

I have 2 plans.

1. Add apis not to increment count.
2. Rewrite gem, modify data store to Redis.

[okuramasafumi]

https://github.com/rails/kredis
Rails now provides kredis which might make it easier to use Redis instead of RDB.