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apply exponential backoff to retrying stale relay connections to reduce energy use

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This commit is contained in:
Bryan Montz
2023-02-23 06:45:14 -06:00
parent 8b9958a4ad
commit e5749c8748
1 changed files with 13 additions and 4 deletions
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17
damus/Nostr/RelayPool.swift
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@@ -39,11 +39,17 @@ struct NostrRequestId: Equatable, Hashable {
} }
class RelayPool { class RelayPool {
/// Used for an exponential backoff algorithm when retrying stale connections
/// Each retry attempt will be delayed by raising this base delay to an exponent
/// equal to the number of previous retries.
private static let base_reconnect_delay: TimeInterval = 2
var relays: [Relay] = [] var relays: [Relay] = []
var handlers: [RelayHandler] = [] var handlers: [RelayHandler] = []
var request_queue: [QueuedRequest] = [] var request_queue: [QueuedRequest] = []
var seen: Set<String> = Set() var seen: Set<String> = Set()
var counts: [String: UInt64] = [:] var counts: [String: UInt64] = [:]
private var retry_attempts_per_relay: [URL: Int] = [:]
var descriptors: [RelayDescriptor] { var descriptors: [RelayDescriptor] {
relays.map { $0.descriptor } relays.map { $0.descriptor }
@@ -99,15 +105,18 @@ class RelayPool {
/// This is used to retry dead connections /// This is used to retry dead connections
func connect_to_disconnected() { func connect_to_disconnected() {
for relay in relays { for relay in relays where !relay.is_broken && !relay.connection.isConnected {
let c = relay.connection let c = relay.connection
let is_connecting = c.isReconnecting || c.isConnecting let is_connecting = c.isReconnecting || c.isConnecting
if is_connecting && (Date.now.timeIntervalSince1970 - c.last_connection_attempt) > 5 { let retry_attempts = retry_attempts_per_relay[c.url] ?? 0
print("stale connection detected (\(relay.descriptor.url.absoluteString)). retrying...") let delay = pow(RelayPool.base_reconnect_delay, TimeInterval(retry_attempts_per_relay[c.url] ?? 0))
if is_connecting && (Date.now.timeIntervalSince1970 - c.last_connection_attempt) > delay {
print("stale connection detected (\(relay.descriptor.url.absoluteString)). retrying after \(delay) seconds...")
relay.connection.connect(force: true) relay.connection.connect(force: true)
} else if relay.is_broken || is_connecting || c.isConnected { retry_attempts_per_relay[c.url] = retry_attempts + 1
} else if is_connecting {
continue continue
} else { } else {
relay.connection.reconnect() relay.connection.reconnect()