In addition to the tenant read lock, schedulers need to also acquire an
exclusive pipeline lock. In case a pipeline is already locked by another
scheduler, it is skipped and processing will continue with the next
pipeline in the tenant.
Tenant management and trigger queues are protected by a queue specific
lock and need to acquire other locks depending on the processed event
(e.g. tenant write lock for tenant reconfigurations).
This also fixes an issue with the locked context manager when an
exception is thrown inside the context. In this case the lock was not
unlocked.
Change-Id: I2e3f0feca7119908d1d13010d2e4de791f95137e
0b95dfd07c