DNSResolver: Let's not cache DNS resolution results anymore

This commit is contained in:
Roopesh Chander 2018-11-08 16:31:42 +05:30
parent 7bde4a6300
commit 40ce2604ea
1 changed files with 9 additions and 17 deletions

View File

@ -12,7 +12,6 @@ class DNSResolver {
let endpoints: [Endpoint?]
let dispatchGroup: DispatchGroup
var dispatchWorkItems: [DispatchWorkItem]
static var cache = NSCache<NSString, NSString>()
init(endpoints: [Endpoint?]) {
self.endpoints = endpoints
@ -20,20 +19,14 @@ class DNSResolver {
self.dispatchGroup = DispatchGroup()
}
func resolveWithoutNetworkRequests() -> [Endpoint?]? {
var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count)
for (i, endpoint) in self.endpoints.enumerated() {
func isAllEndpointsAlreadyResolved() -> Bool {
for endpoint in self.endpoints {
guard let endpoint = endpoint else { continue }
if (endpoint.hasHostAsIPAddress()) {
resolvedEndpoints[i] = endpoint
} else if let resolvedEndpointStringInCache = DNSResolver.cache.object(forKey: endpoint.stringRepresentation() as NSString),
let resolvedEndpointInCache = Endpoint(from: resolvedEndpointStringInCache as String) {
resolvedEndpoints[i] = resolvedEndpointInCache
} else {
return nil
if (!endpoint.hasHostAsIPAddress()) {
return false
}
}
return resolvedEndpoints
return true
}
func resolveSync() throws -> [Endpoint?] {
@ -41,19 +34,18 @@ class DNSResolver {
let dispatchGroup = self.dispatchGroup
dispatchWorkItems = []
if (isAllEndpointsAlreadyResolved()) {
return endpoints
}
var resolvedEndpoints: [Endpoint?] = Array<Endpoint?>(repeating: nil, count: endpoints.count)
var isResolvedByDNSRequest: [Bool] = Array<Bool>(repeating: false, count: endpoints.count)
for (i, endpoint) in self.endpoints.enumerated() {
guard let endpoint = endpoint else { continue }
if (endpoint.hasHostAsIPAddress()) {
resolvedEndpoints[i] = endpoint
} else if let resolvedEndpointStringInCache = DNSResolver.cache.object(forKey: endpoint.stringRepresentation() as NSString),
let resolvedEndpointInCache = Endpoint(from: resolvedEndpointStringInCache as String) {
resolvedEndpoints[i] = resolvedEndpointInCache
} else {
let workItem = DispatchWorkItem {
resolvedEndpoints[i] = DNSResolver.resolveSync(endpoint: endpoint)
isResolvedByDNSRequest[i] = true
}
dispatchWorkItems.append(workItem)
DispatchQueue.global(qos: .userInitiated).async(group: dispatchGroup, execute: workItem)