This reverts commit 0b25a06a

Each thread has its own rados context. The thead pool, when used will allow better
parallelism of asynchronous requests.

This required some rework on the backend creations as the threads will need logging.

This will limit contention on the scheduling lock when there is no new mount to schedule (which
is the majority of the time).

Fixed errors generated by Scheduler code passing getMessage() instead of getMessage().str() to ScopedParamContainer.add()

They prevented propoer statistics update.

This allowed the archive requeuest to be removed from ownership bulk.
Also adapted unit tests and related Mocks (mainly MockArchiveMount).
Removed unused functions from job level updating.

This will enable better integration and bulk archive jobs ownership removal from agent.

Some typo fixes.

This will remove contention on the drive register as drives uipdate their statuses.
Also simplified structures in OStoreDB implementation (less references with added friend relations).

The problem happened in tests when the object we deleted by hand. This commit
prevents a crash in this (already pathological) situation.

A benign exception failed to be caught and led to unnecessary errors.

The locking of the scheduler global lock is retained so only on drive can create a mount at any point in time.

Command will remove drive or drives by regex from the drive register.
The drives must be in state Down unless --force option is set.
Usage: rm <drive_name> [--force/-f]

If there is any active tapeserver with this drive it will create the
entry in the drive register again with Down status.

Example of the usage:
  cta drive rm ^VDSTK
  Drive VDSTK41 in state Free and force is not set (skipped).
  Drive VDSTK42 removed.

This would detect instances where rados reports an object deletion before is actually happens.

The updating of statistic in the objecttore (in drive register) could wait for a lock
for so long that the session get killed due to a heatbeat timeout.

To avoid this, we use lockfree access as much as possible, and when locking it srequired, do it with a
timeout.

The timeout will be logged as a warning.

Added timeouts to synchronous locking primitives in the object store backends to implement this feature.

Fixed a bug where the VFS backend always used exclusive locks.

The probe state is also used. It represents the time when the drive is being checked
for tapes during the down to up transition.

Shutdown is not in use yet as it requires changing the behaviour of the system (clean shutdowns).

It was deleted by commit 19f05c41 but as soon as
scheduler code shared with frontend we need it.

Add unitName parameter for the logging.

Also replace all drive, Drive, DiskUnit, diskUnit log parameters with
 unitName.

Fix output for lpa.

Add mini help printing for all cta commands.

Add logging for the tape VID for potential mounts of retrieve
requests in Scheduler::getNextMount

Also added some lockfree fetches.