nodes and audit_history tables
This PR removes all code reference to audit_histories table and
```
audit_reputation_alpha, audit_reputation_beta,
unknown_audit_reputation_alpha, unknown_audit_reputation_beta,
```
columns from nodes table.
It also drops audit_histories table from the db since the code
that's referencing it currently are not being used.
Change-Id: Ifcda8db36afb3a333d487ff831f2fdefc8b02a4c
* Separate audit history interface into its own file in the overlay
package
* Add overlay.AuditHistory struct so that internalpb.AuditHistory is
only used from within the database layer
* Add overlay.GetAuditHistory function for features that will require
access to detailed audit history information
* Do not return full audit history from UpdateAuditHistory - callers to
that function only need to know the online score and whether a full
tracking period has been completed
* Move audit history tests out of satellite/satellitedb, since they are
independent of database implementation
Change-Id: I35b0c4ac23bbaabd80624f8a9631c3cb1a1f33bd
Previously if a node did not have audit history data for each of the
windows over the tracking period, we would give them the benefit of
the doubt and set their score to 1. This was to prevent nodes from
being suspended right out the gate. We need a minimum amount of data
to evaluate them.
However, a node who is actually failing at being online will have no
idea until they have received enough audits and we suspend them.
Instead, we will always use their real score, but use a flag to determine
whether they are eligible for suspension/dq.
Change-Id: I382218f12e8770f95d4bcddcf101ef348940cadf
Add a function to the overlay cache called UpdateAuditHistory, which
allows us to add online or offline audits to a particular node's audit
history, and get that node's "online score" for the configured tracking
period.
The next step will be to use UpdateAuditHistory from inside
BatchUpdateStats/UpdateStats, so that audit history is actually updated
when nodes get audited, and we can suspend nodes based on their online
score.
Change-Id: I2289105e6961e68e829a987ff756b0e576fab120
