rapid_gossip_sync_downloader.swift

// first, download the gossip data
print("Sending rapid gossip sync request…");
var request = URLRequest(url: URL(string: "https://rapidsync.lightningdevkit.org/snapshot/0")!)
request.httpMethod = "GET"

let startA = DispatchTime.now()
let (data, _) = try await URLSession.shared.data(for: request)
let finishA = DispatchTime.now()
let elapsedA = Double(finishA.uptimeNanoseconds-startA.uptimeNanoseconds)/1_000_000_000
print("Received rapid gossip sync response: \(data.count) bytes! Time: \(elapsedA)s");

let reversedGenesisHashHex = "6fe28c0ab6f1b372c1a6a246ae63f74f931e8365e15a089c68d6190000000000"
let reversedGenesisHash = PolarIntegrationSample.hexStringToBytes(hexString: reversedGenesisHashHex)!

let logger = LDKTraitImplementations.PolarLogger()
let networkGraph = NetworkGraph(genesis_hash: reversedGenesisHash, logger: logger)
let rapidSync = RapidGossipSync(network_graph: networkGraph)

let gossipDataRaw = [UInt8](data)
print("Applying rapid sync data…")
let startB = DispatchTime.now()
let timestamp = rapidSync.update_network_graph(update_data: gossipDataRaw)
if let error = timestamp.getError() {
    print("error! type: \(error.getValueType())")
    let specificError = error.getValueAsLightningError()
    print("details: \(specificError?.get_err())")
}
let finishB = DispatchTime.now()
let elapsedB = Double(finishB.uptimeNanoseconds-startB.uptimeNanoseconds)/1_000_000_000
print("Applied rapid sync data: \(timestamp.getValue())! Time: \(elapsedB)s")

print("Measuring graph size…")
let startC = DispatchTime.now()
let graphBytes = networkGraph.write()
let finishC = DispatchTime.now()
let elapsedC = Double(finishC.uptimeNanoseconds-startC.uptimeNanoseconds)/1_000_000_000
print("Network graph size: \(graphBytes.count)! Time: \(elapsedC)s")