RFC: Rework Pinning interface

[kevina]

In order to finish #2962 I would like to to rework the Pinner interface a bit:

(1) Fix all commands to accept multiple pins at once for to improve performance from O(N*P) to O(P) where P is the number of (possible indirectly) pinned blocks and N is the number of operations to perform related to pinning.

(1.1) Possible provide a function to Walk all pins and perform arbitrary operations on them.

(2) Provide a function/method to verify all pins. That is to report any pins that are missing or recursive pins that are broken.

(3) I am not sure, but using a RWLock seams like an overkill. A simple mutex should be sufficient. All operations should get what they need from the pinner struct and then release the lock rather than holding a RWLock for the entire operation.

Comments?

[kevina]

This issue is no longer relevant.