func startNotifier()

in Sources/OTelCommon/Reachability.swift [172:224]
39 lines of code
3 McCabe index (conditional complexity)

    func startNotifier() throws {
        guard !notifierRunning else { return }

        let callback: SCNetworkReachabilityCallBack = { (reachability, flags, info) in
            guard let info = info else { return }

            // `weakifiedReachability` is guaranteed to exist by virtue of our
            // retain/release callbacks which we provided to the `SCNetworkReachabilityContext`.
            let weakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info).takeUnretainedValue()

            // The weak `reachability` _may_ no longer exist if the `Reachability`
            // object has since been deallocated but a callback was already in flight.
            weakifiedReachability.reachability?.flags = flags
        }

        let weakifiedReachability = ReachabilityWeakifier(reachability: self)
        let opaqueWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.passUnretained(weakifiedReachability).toOpaque()

        var context = SCNetworkReachabilityContext(
            version: 0,
            info: UnsafeMutableRawPointer(opaqueWeakifiedReachability),
            retain: { (info: UnsafeRawPointer) -> UnsafeRawPointer in
                let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
                _ = unmanagedWeakifiedReachability.retain()
                return UnsafeRawPointer(unmanagedWeakifiedReachability.toOpaque())
            },
            release: { (info: UnsafeRawPointer) -> Void in
                let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
                unmanagedWeakifiedReachability.release()
            },
            copyDescription: { (info: UnsafeRawPointer) -> Unmanaged<CFString> in
                let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
                let weakifiedReachability = unmanagedWeakifiedReachability.takeUnretainedValue()
                let description = weakifiedReachability.reachability?.description ?? "nil"
                return Unmanaged.passRetained(description as CFString)
            }
        )

        if !SCNetworkReachabilitySetCallback(reachabilityRef, callback, &context) {
            stopNotifier()
            throw ReachabilityError.unableToSetCallback(SCError())
        }

        if !SCNetworkReachabilitySetDispatchQueue(reachabilityRef, reachabilitySerialQueue) {
            stopNotifier()
            throw ReachabilityError.unableToSetDispatchQueue(SCError())
        }

        // Perform an initial check
        try setReachabilityFlags()

        notifierRunning = true
    }