Set network coordinates from BeaconChain

[samuelmanzanera]

Description

This PR implement the full integration of the network patch in the beacon by building the latency matrix from all the subsets to determine the global network patch.

Fixes #72

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

After running two nodes, the default network patch (being the geo patch) should change based on the latency between the nodes and be persisted into the memory table for the P2P view.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Neylix]

Complex to understand as there is a lot of math and sorted list with index ...

But I can see something that may goes wrong, when the subset enter in handle_summary function, it request the network stats of other nodes. Then when stats are retrieved the pop_slots function is called on SummaryCache which empty the ets table and remove the backup.
But when a node request network stats, the result is streamed from the ets table of SummaryCache but if the requested node quickly requested network patches and pop the slots, it will not be able to respond to the GetNetworkStats message

[samuelmanzanera]

Complex to understand as there is a lot of math and sorted list with index ...

But I can see something that may goes wrong, when the subset enter in handle_summary function, it request the network stats of other nodes. Then when stats are retrieved the pop_slots function is called on SummaryCache which empty the ets table and remove the backup. But when a node request network stats, the result is streamed from the ets table of SummaryCache but if the requested node quickly requested network patches and pop the slots, it will not be able to respond to the GetNetworkStats message

It might be true, we might schedule the removal of the cache a bit later, maybe after the self-repair scheduling time.

[Neylix]

I got this error after some time :

A patch has only 2 digits (log in network_distance function from P2P)

[Neylix]

It looks like the problem of the pathc with only 2 digits is still there

[Neylix]

Working well now, I'm just thinking we should create an issue or maybe do it in this one, to add the network patch in the beaconChainSummary graphql API. (in the transform function)