feat: Cache configuration for a given ClientSession #959
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| // | ||
| // Cache.swift | ||
| // PrimerSDK | ||
| // | ||
| // Created by Niall Quinn on 31/07/24. | ||
| // | ||
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| import Foundation | ||
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| class Cache<Key: Hashable, Value> { | ||
| private let cache = NSCache<WrappedKey, Entry>() | ||
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| func insert(_ value: Value, forKey key: Key) { | ||
| cache.setObject(Entry(value: value), forKey: WrappedKey(key)) | ||
| } | ||
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| func value(forKey key: Key) -> Value? { | ||
| guard let entry = cache.object(forKey: WrappedKey(key)) else { | ||
| return nil | ||
| } | ||
| return entry.value | ||
| } | ||
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| func removeValue(forKey key: Key) { | ||
| cache.removeObject(forKey: WrappedKey(key)) | ||
| } | ||
| } | ||
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| private extension Cache { | ||
| final class WrappedKey: NSObject { | ||
| let key: Key | ||
| init(_ key: Key) { self.key = key } | ||
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| override var hash: Int { return key.hashValue } | ||
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| override func isEqual(_ object: Any?) -> Bool { | ||
| guard let value = object as? WrappedKey else { | ||
| return false | ||
| } | ||
| return value.key == key | ||
| } | ||
| } | ||
| } | ||
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| private extension Cache { | ||
| final class Entry { | ||
| let value: Value | ||
| init(value: Value) { self.value = value } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| // | ||
| // ConfigurationCache.swift | ||
| // PrimerSDK | ||
| // | ||
| // Created by Niall Quinn on 31/07/24. | ||
| // | ||
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| import Foundation | ||
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| protocol ConfigurationCaching { | ||
| func clearCache() | ||
| func setData(_ data: ConfigurationCachedData, forKey key: String) | ||
| func data(forKey key: String) -> ConfigurationCachedData? | ||
| } | ||
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| class ConfigurationCache: ConfigurationCaching { | ||
| static let shared = ConfigurationCache() | ||
| private var cache = Cache<String, ConfigurationCachedData>() | ||
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| func clearCache() { | ||
| cache = Cache<String, ConfigurationCachedData>() | ||
| } | ||
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| func data(forKey key: String) -> ConfigurationCachedData? { | ||
| if let cachedData = cache.value(forKey: key) { | ||
| if validateCachedConfig(key: key, cachedData: cachedData) == false { | ||
| cache.removeValue(forKey: key) | ||
| return nil | ||
| } | ||
| return cachedData | ||
| } | ||
| return nil | ||
| } | ||
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| func setData(_ data: ConfigurationCachedData, forKey key: String) { | ||
| // Cache includes at most one cached configuration | ||
| clearCache() | ||
| cache.insert(data, forKey: key) | ||
| } | ||
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| private func validateCachedConfig(key: String, cachedData: ConfigurationCachedData) -> Bool { | ||
| let timestamp = cachedData.timestamp | ||
| let now = Date().timeIntervalSince1970 | ||
| let timeInterval = now - timestamp | ||
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| if timeInterval > cachedData.ttl { | ||
| return false | ||
| } | ||
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| return true | ||
| } | ||
| } | ||
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| class ConfigurationCachedData { | ||
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| let config: PrimerAPIConfiguration | ||
| let timestamp: TimeInterval | ||
| let ttl: TimeInterval | ||
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| init(config: PrimerAPIConfiguration, headers: [String: String]? = nil) { | ||
| //Extract ttl from headers | ||
| self.config = config | ||
| self.timestamp = Date().timeIntervalSince1970 | ||
| self.ttl = Self.extractTtlFromHeaders(headers) | ||
| } | ||
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| static let FallbackCacheExpiration: TimeInterval = 0 | ||
| static let CacheHeaderKey = "x-primer-session-cache-ttl" | ||
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| private static func extractTtlFromHeaders(_ headers: [String: String]?) -> TimeInterval { | ||
| guard let headers, | ||
| let ttlHeaderValue = headers[Self.CacheHeaderKey], | ||
| let ttlInt = Int(ttlHeaderValue) else { | ||
| return Self.FallbackCacheExpiration | ||
| } | ||
| return TimeInterval(ttlInt) | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -8,6 +8,7 @@ internal protocol PrimerAPIConfigurationModuleProtocol { | |
| static var clientToken: JWTToken? { get } | ||
| static var decodedJWTToken: DecodedJWTToken? { get } | ||
| static var apiConfiguration: PrimerAPIConfiguration? { get } | ||
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| static func resetSession() | ||
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| func setupSession( | ||
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@@ -25,6 +26,11 @@ internal class PrimerAPIConfigurationModule: PrimerAPIConfigurationModuleProtoco | |
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| static var apiClient: PrimerAPIClientProtocol? | ||
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| private static let queue = DispatchQueue(label: "com.primer.configurationQueue") | ||
| private static var pendingPromises: [String: Promise<PrimerAPIConfiguration>] = [:] | ||
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| private let logger = PrimerLogging.shared.logger | ||
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| static var clientToken: JWTToken? { | ||
| get { | ||
| if PrimerAPIConfigurationModule.decodedJWTToken == nil { | ||
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@@ -66,6 +72,13 @@ internal class PrimerAPIConfigurationModule: PrimerAPIConfigurationModuleProtoco | |
| return decodedJWTToken | ||
| } | ||
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| static var cacheKey: String? { | ||
| guard let cacheKey = Self.clientToken else { | ||
| return nil | ||
| } | ||
| return cacheKey | ||
| } | ||
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| static func resetSession() { | ||
| AppState.current.clientToken = nil | ||
| AppState.current.apiConfiguration = nil | ||
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@@ -102,7 +115,8 @@ internal class PrimerAPIConfigurationModule: PrimerAPIConfigurationModuleProtoco | |
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| func updateSession(withActions actionsRequest: ClientSessionUpdateRequest) -> Promise<Void> { | ||
| return Promise { seal in | ||
| guard let decodedJWTToken = PrimerAPIConfigurationModule.decodedJWTToken, | ||
| let cacheKey = Self.cacheKey else { | ||
| let err = PrimerError.invalidClientToken(userInfo: .errorUserInfoDictionary(), | ||
| diagnosticsId: UUID().uuidString) | ||
| ErrorHandler.handle(error: err) | ||
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@@ -112,11 +126,15 @@ internal class PrimerAPIConfigurationModule: PrimerAPIConfigurationModuleProtoco | |
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| let apiClient: PrimerAPIClientProtocol = PrimerAPIConfigurationModule.apiClient ?? PrimerAPIClient() | ||
| apiClient.requestPrimerConfigurationWithActions(clientToken: decodedJWTToken, | ||
| request: actionsRequest) { result, responseHeaders in | ||
| switch result { | ||
| case .success(let configuration): | ||
| _ = ImageFileProcessor().process(configuration: configuration).ensure { | ||
| PrimerAPIConfigurationModule.apiConfiguration?.clientSession = configuration.clientSession | ||
| let cachedData = ConfigurationCachedData(config: configuration, headers: responseHeaders) | ||
| ConfigurationCache.shared.setData(cachedData, forKey: cacheKey) | ||
| seal.fulfill() | ||
| } | ||
| case .failure(let err): | ||
| seal.reject(err) | ||
| } | ||
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@@ -244,28 +262,72 @@ internal class PrimerAPIConfigurationModule: PrimerAPIConfigurationModuleProtoco | |
| } | ||
| } | ||
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| // swiftlint:disable:next function_body_length | ||
| private func fetchConfiguration(requestDisplayMetadata: Bool) -> Promise<PrimerAPIConfiguration> { | ||
| return Promise { seal in | ||
| guard let clientToken = PrimerAPIConfigurationModule.decodedJWTToken, | ||
| let cacheKey = Self.cacheKey else { | ||
| let err = PrimerError.invalidClientToken(userInfo: .errorUserInfoDictionary(), | ||
| diagnosticsId: UUID().uuidString) | ||
| ErrorHandler.handle(error: err) | ||
| seal.reject(err) | ||
| return | ||
| } | ||
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| PrimerAPIConfigurationModule.queue.sync { | ||
| if let cachedConfig = ConfigurationCache.shared.data(forKey: cacheKey) { | ||
| let event = Analytics.Event.message( | ||
| message: "Configuration cache hit with key: \(cacheKey)", | ||
| messageType: .info, | ||
| severity: .info | ||
| ) | ||
| Analytics.Service.record(event: event) | ||
| logger.debug(message: "Cached config used") | ||
| seal.fulfill(cachedConfig.config) | ||
| return | ||
| } | ||
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| if let pendingPromise = PrimerAPIConfigurationModule.pendingPromises[cacheKey as String] { | ||
| pendingPromise.done { config in | ||
| seal.fulfill(config) | ||
| }.catch { error in | ||
| seal.reject(error) | ||
| } | ||
| return | ||
| } | ||
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| let promise = Promise<PrimerAPIConfiguration> { innerSeal in | ||
| let requestParameters = Request.URLParameters.Configuration( | ||
| skipPaymentMethodTypes: [], | ||
| requestDisplayMetadata: requestDisplayMetadata) | ||
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| let apiClient: PrimerAPIClientProtocol = PrimerAPIConfigurationModule.apiClient ?? PrimerAPIClient() | ||
| apiClient.fetchConfiguration(clientToken: clientToken, requestParameters: requestParameters) { (result, responseHeaders) in | ||
| switch result { | ||
| case .failure(let err): | ||
| innerSeal.reject(err) | ||
| case .success(let config): | ||
| _ = ImageFileProcessor().process(configuration: config).ensure { | ||
| // Cache the result | ||
| let cachedData = ConfigurationCachedData(config: config, headers: responseHeaders) | ||
| ConfigurationCache.shared.setData(cachedData, forKey: cacheKey) | ||
| innerSeal.fulfill(config) | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| PrimerAPIConfigurationModule.pendingPromises[cacheKey as String] = promise | ||
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| promise.done { config in | ||
| seal.fulfill(config) | ||
| }.catch { error in | ||
| seal.reject(error) | ||
| } | ||
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| promise.ensure { | ||
| PrimerAPIConfigurationModule.queue.async { | ||
|
There was a problem hiding this comment. I suspect there is a small chance here that you could end up adding a callback here that is never returned because it was added after ensure was called but prior to the queued item completing. I don't think this will play out in practice but worth thinking of whether there's a way to further streamline the promise-nesting to avoid this in the future. (Which is admittedly easier said than done!) |
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| PrimerAPIConfigurationModule.pendingPromises.removeValue(forKey: cacheKey as String) | ||
| } | ||
| } | ||
| } | ||
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This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
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Is there a potential case for having a
SingleItemCachewrapper aroundNSCacheinstead? Then the key could be passed in the init and removed from all the upstream methods hereMy concern would be someone seeing this and thinking that it supports multiple configurations because of the provision of a
key