Less aggressive peer discovery

[benaadams]

Changes

When the number of connected Peers is not at max (fairly common) and the Peer's db is fairly mature; the reconnection will accesses the NodeStatsManager's nodeStats ConcurrentDictionary more frequently than the VM calls UpdateGas (which is every op executed)

• Cache hashcode in Node
• Replace locking in NodeStatsLight with Volatile.Read and Interlocked.Increment
• Stop NodeStatsManager timer running while executing
• Cache INodeStats object in Peer rather than looking it up from ConcurrentDictionary on each method call
• Throttle PeerManager if in a hot discovery loop; by up to 50ms per set of candidates

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

[asdacap]

Whoa its called that much!?