router-perf@1.0 — Erlang Execution Device for Performance-Based Routing

[Lucifer0x17]

Continuation of #737

Summary

Introduces dev_router_perf.erl, an Erlang execution device for process@1.0 that provides performance-based routing with automatic weight adjustment. It replaces dynamic-router.lua for Arweave gateway routing, supporting match/with route format — Arweave gateways use match/with instead of prefix/price/topup

How It Works

The device runs as a process@1.0 node process. The feedback loop:

           ┌─────────────────────────────────────────────────┐
           │                                                 │
           ▼                                                 │
   HTTP Request arrives                                      │
           │                                                 │
           ▼                                                 │
   dev_router:route                                          │
     └─ load_routes via provider ──► GET /perf-router~       │
        node-process@1.0/now/routes                          │
     └─ choose(N, "By-Weight") uses weights                  │
     └─ apply_route injects http_reference                   │
           │                                                 │
           ▼                                                 │
   hb_http_client fans out to selected gateways              │
           │                                                 │
           ▼                                                 │
   Response completes                                        │
     └─ record_duration → maybe_invoke_monitor               │
     └─ POST to /perf-router~node-process@1.0/schedule       │
        with {duration, reference, ...}                      │
           │                                                 │
           ▼                                                 │
   dev_router_perf:compute                                   │
     └─ duration/3 updates node performance via EMA ─────────┘
        new_perf = old * (1 - 1/period) + duration * (1/period)

Actions

Action	Description
register	Add a node to a route. Supports match/with and prefix formats. Sets http_reference for the feedback loop.
duration	Update a node's performance score using exponential moving average (EMA). Matches node by http_reference.
recalculate	Recompute weights for all nodes using decay-based percentile scoring. Called automatically after each register.

Configuration

Set these on the node process definition:

These are example values can be configured differently.

Key	Default	Description
performance-period	1000	EMA smoothing period. Lower = more responsive.
initial-performance	30000	Starting perf score (ms) for new nodes.
sampling-rate	0.1	Fraction of random sampling to prevent starvation.
performance-weight	1	Weight factor for performance in scoring.
pricing-weight	1	Weight factor for price in scoring.
score-preference	1	Decay exponent — higher values penalize slower nodes more aggressively.

Production Setup

1. Node configuration:

AdditionalOpts = #{
    http_monitor => #{
        <<"method">> => <<"POST">>,
        <<"path">> => <<"/perf-router~node-process@1.0/schedule">>
    },
    router_opts => #{
        <<"provider">> => #{
            <<"path">> => <<"/perf-router~node-process@1.0/now/routes">>
        }
    },
    node_processes => #{
        <<"perf-router">> => #{
            <<"device">> => <<"process@1.0">>,
            <<"execution-device">> => <<"router-perf@1.0">>,
            <<"scheduler-device">> => <<"scheduler@1.0">>,
            <<"performance-period">> => 6,
            <<"initial-performance">> => 30000
        }
    },
    routes => [
        #{<<"template">> => <<"^/arweave">>,
          <<"nodes">> => BootstrapNodes,
          <<"parallel">> => true,
          <<"admissible-status">> => 200}
    ]
}).

2. Register gateways (once, at startup or via admin script):

lists:foreach( fun(GatewayNode) ->
    Body = 
           hb_message:commit(#{
                  <<"action">> => <<"register">>,
                  <<"route">> => 
                          maps:merge(
                                   GatewayNode, 
                                   #{
                                          <<"template">> => <<"^/arweave">>,
                                          <<"parallel">> => true,
                                          <<"strategy">> => <<"Random">>,
                                          <<"choose">> => 10,
                                          <<"admissible-status">> => 200
                                    }
                           )
                  }, 
                  Opts
           ),
    hb_http:post(
         Node, 
         #{
              <<"path">> => <<"/perf-router~node-process@1.0/schedule">>,
              <<"method">> => <<"POST">>,
              <<"body">> => Body
         }, 
         Opts
    )
end, GatewayNodes).

3. Verify:

# Check routes and weights
curl "http://localhost:PORT/perf-router~node-process@1.0/now/routes?require-codec=application/json&accept-bundle=true"

# Check a specific node's performance score
curl "http://localhost:PORT/perf-router~node-process@1.0/now/routes/1/nodes/1/performance"

[samcamwilliams]

Amazing! dynamic-router.lua takes a new, faster form 🫡

If it is like the original the registration process should just be either:

1. Permissioned: Hard-coded in the node message on start. If it is like the Lua script you should just be able to literally put the starting routes in your local process. In this mode is-admissible would always return false.
2. Permissionless: In this case, if the deployment is going to use the ~arweave@2.9/admissible-tx-response flow then there is no need to gate access at all. Anyone should be able to register on the /ID route.
   ...in either case, no need for the lists:foreach(...) custom code.

Congrats! Let's ship it and test a beta 🙂