Prevent duplicate v1/configuration GET requests (#1363)

braintree · Jul 16, 2024 · 10a0254 · 10a0254
1 parent 96a910d
commit 10a0254
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Showing 5 changed files with 74 additions and 19 deletions.
diff --git a/Braintree.xcodeproj/project.pbxproj b/Braintree.xcodeproj/project.pbxproj
@@ -117,6 +117,7 @@
 		80581A8C25531D0A00006F53 /* BTConfiguration+ThreeDSecure_Tests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 80581A8B25531D0A00006F53 /* BTConfiguration+ThreeDSecure_Tests.swift */; };
 		80581B1D2553319C00006F53 /* BTGraphQLHTTP_SSLPinning_IntegrationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 80581B1C2553319C00006F53 /* BTGraphQLHTTP_SSLPinning_IntegrationTests.swift */; };
 		806C85632B90EBED00A2754C /* PrivacyInfo.xcprivacy in Resources */ = {isa = PBXBuildFile; fileRef = 806C85622B90EBED00A2754C /* PrivacyInfo.xcprivacy */; };
+		807296042C41B63F0093F2AB /* ConfigurationCallbackStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 807296032C41B63F0093F2AB /* ConfigurationCallbackStorage.swift */; };
 		8075CBEE2B1B735200CA6265 /* BTAPIRequest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8075CBED2B1B735200CA6265 /* BTAPIRequest.swift */; };
 		80842DA72B8E49EF00A5CD92 /* PrivacyInfo.xcprivacy in Resources */ = {isa = PBXBuildFile; fileRef = 80842DA62B8E49EF00A5CD92 /* PrivacyInfo.xcprivacy */; };
 		8087C10F2BFBACCA0020FC2E /* TokenizationKey_Tests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8087C10E2BFBACCA0020FC2E /* TokenizationKey_Tests.swift */; };
@@ -855,6 +856,7 @@
 		8064F3942B1E4FEB0059C4CB /* BTShopperInsightsClient_Tests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BTShopperInsightsClient_Tests.swift; sourceTree = "<group>"; };
 		8064F3962B1E63800059C4CB /* BTShopperInsightsRequest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BTShopperInsightsRequest.swift; sourceTree = "<group>"; };
 		806C85622B90EBED00A2754C /* PrivacyInfo.xcprivacy */ = {isa = PBXFileReference; lastKnownFileType = text.xml; path = PrivacyInfo.xcprivacy; sourceTree = "<group>"; };
+		807296032C41B63F0093F2AB /* ConfigurationCallbackStorage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConfigurationCallbackStorage.swift; sourceTree = "<group>"; };
 		8075CBED2B1B735200CA6265 /* BTAPIRequest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BTAPIRequest.swift; sourceTree = "<group>"; };
 		80842DA62B8E49EF00A5CD92 /* PrivacyInfo.xcprivacy */ = {isa = PBXFileReference; lastKnownFileType = text.xml; path = PrivacyInfo.xcprivacy; sourceTree = "<group>"; };
 		8087C10E2BFBACCA0020FC2E /* TokenizationKey_Tests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TokenizationKey_Tests.swift; sourceTree = "<group>"; };
@@ -1433,6 +1435,7 @@
 				BEBD05212A1FE8BE0003C15C /* BTWebAuthenticationSession.swift */,
 				BEB9BF522A26872B00A3673E /* BTWebAuthenticationSessionClient.swift */,
 				BE698EA128AA8EEA001D9B10 /* ConfigurationCache.swift */,
+				807296032C41B63F0093F2AB /* ConfigurationCallbackStorage.swift */,
 				45EFC3962C2DBF32005E7F5B /* ConfigurationLoader.swift */,
 				80D280CC2BE9354B00762D27 /* Date+MillisecondTimestamp.swift */,
 				80F86FEF29FC2ED6003297FF /* Encodable+Dictionary.swift */,
@@ -3258,6 +3261,7 @@
 				800E78C429E0DD5300D1B0FC /* FPTIBatchData.swift in Sources */,
 				BED00CB028A579D700D74AEC /* BTClientToken.swift in Sources */,
 				5708E0A628809AD9007946B9 /* BTJSON.swift in Sources */,
+				807296042C41B63F0093F2AB /* ConfigurationCallbackStorage.swift in Sources */,
 				574891ED286F7ECA0020DA36 /* BTClientMetadata.swift in Sources */,
 				BE24C66E28E49A730067B11A /* BTAPIClientError.swift in Sources */,
 				BC17F9BC28D24C9E004B18CC /* BTGraphQLErrorTree.swift in Sources */,

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Braintree iOS SDK Release Notes
 
+## unreleased
+* Prevent duplicate outbound `v1/configuration` requests
+
 ## 6.23.0 (2024-07-15)
 * BraintreeShopperInsights (BETA)
   * Add error when using an invalid authorization type

diff --git a/Sources/BraintreeCore/ConfigurationCallbackStorage.swift b/Sources/BraintreeCore/ConfigurationCallbackStorage.swift
@@ -0,0 +1,26 @@
+import Foundation
+
+/// Used to store, access, and manage an array of to-be-invoked `BTConfiguration` GET result callbacks in a thread-safe manner
+class ConfigurationCallbackStorage {
+
+    private let queue = DispatchQueue(label: "com.braintreepayments.ConfigurationCallbackStorage")
+    private var pendingCompletions: [(BTConfiguration?, Error?) -> Void] = []
+
+    /// The number of completions that are waiting to be invoked
+    var count: Int {
+        queue.sync { pendingCompletions.count }
+    }
+
+    /// Adds a pending, yet to-be-invoked completion handler
+    func add(_ completion: @escaping (BTConfiguration?, Error?) -> Void) {
+        queue.sync { pendingCompletions.append(completion) }
+    }
+
+    /// Executes and clears all pending completion handlers
+    func invoke(_ configuration: BTConfiguration?, _ error: Error?) {
+        queue.sync {
+            pendingCompletions.forEach { $0(configuration, error) }
+            pendingCompletions.removeAll()
+        }
+    }
+}
diff --git a/Sources/BraintreeCore/ConfigurationLoader.swift b/Sources/BraintreeCore/ConfigurationLoader.swift
@@ -7,6 +7,7 @@ class ConfigurationLoader {
     private let configPath = "v1/configuration"
     private let configurationCache = ConfigurationCache.shared
     private let http: BTHTTP
+    private let pendingCompletions = ConfigurationCallbackStorage()
 
     // MARK: - Intitializer
 
@@ -39,26 +40,32 @@ class ConfigurationLoader {
             completion(cachedConfig, nil)
             return
         }
-
-        http.get(configPath, parameters: BTConfigurationRequest()) { [weak self] body, response, error in
-            guard let self else {
-                completion(nil, BTAPIClientError.deallocated)
-                return
-            }
-
-            if let error {
-                completion(nil, error)
-                return
-            } else if response?.statusCode != 200 || body == nil {
-                completion(nil, BTAPIClientError.configurationUnavailable)
-                return
-            } else {
-                let configuration = BTConfiguration(json: body)
-
-                try? configurationCache.putInCache(authorization: http.authorization.bearer, configuration: configuration)
+
+        pendingCompletions.add(completion)
+
+        // If this is the 1st `v1/config` GET attempt, proceed with firing the network request.
+        // Otherwise, there is already a pending network request.
+        if pendingCompletions.count == 1 {
+            http.get(configPath, parameters: BTConfigurationRequest()) { [weak self] body, response, error in
+                guard let self else {
+                    self?.notifyCompletions(nil, BTAPIClientError.deallocated)
+                    return
+                }
 
-                completion(configuration, nil)
-                return
+                if let error {
+                    notifyCompletions(nil, error)
+                    return
+                } else if response?.statusCode != 200 || body == nil {
+                    notifyCompletions(nil, BTAPIClientError.configurationUnavailable)
+                    return
+                } else {
+                    let configuration = BTConfiguration(json: body)
+
+                    try? configurationCache.putInCache(authorization: http.authorization.bearer, configuration: configuration)
+
+                    notifyCompletions(configuration, nil)
+                    return
+                }
             }
         }
     }
@@ -74,4 +81,10 @@ class ConfigurationLoader {
             }
         }
     }
+
+    // MARK: - Private Methods
+
+    func notifyCompletions(_ configuration: BTConfiguration?, _ error: Error?) {
+        pendingCompletions.invoke(configuration, error)
+    }
 }
diff --git a/UnitTests/BraintreeCoreTests/ConfigurationLoader_Tests.swift b/UnitTests/BraintreeCoreTests/ConfigurationLoader_Tests.swift
@@ -131,4 +131,13 @@ class ConfigurationLoader_Tests: XCTestCase {
             XCTAssertEqual(error as NSError, mockError)
         }
     }
+
+    func testGetConfig_whenCalledInQuickSequence_onlySendsOneNetworkRequest() {
+        sut.getConfig() { _, _ in }
+        sut.getConfig() { _, _ in }
+        sut.getConfig() { _, _ in }
+        sut.getConfig() { _, _ in }
+
+        XCTAssertEqual(mockHTTP.GETRequestCount, 1)
+    }
 }