Tag mesh peers on graft, remove tags on prune

[achingbrain]

To prevent the connection manager pruning connections to high-value peers, modules that need connections to certain peers should tag them to ensure they don't get culled by the connection manager when connection limits have been specified and reached.

When this module grafts mesh peers for a given topic, it should use the peerStore.tagPeer method to tag them with a value:

libp2p.peerStore.tagPeer(peerId, 'gossipsub-mesh-peer', {
  value: 100 // value should be 0-100
})

When they are pruned from a mesh peerStore.unTagPeer should be used:

libp2p.peerStore.unTagPeer(peerId, 'gossipsub-mesh-peer')

Refs: libp2p/js-libp2p#369

[dapplion]

Do other implementations have this feature? I don't recall seeing it. Speaking for Lodestar we have more complex logic to decide the value of the peer so this feature won't be useful at all. Gossipsub also has it's own scoring system, which indirectly affects if a peer is meshed or not tho.

[achingbrain]

Do other implementations have this feature? I don't recall seeing it.

See the referenced issue in the OP for context.

Speaking for Lodestar we have more complex logic to decide the value of the peer

If that's the case lodestar may wish to tag high value peers as well.

[dapplion]

If that's the case lodestar may wish to tag high value peers as well.

If I understand this feature is relevant because the connection manager may choose to disconnect peers at will right? Can consumers completely disable that so peer management is done 100% by the consumer?

[achingbrain]

Yes, just leave maxConnections and maxEventLoopDelay as the default (both Infinity).