Fix/dispatch queue (#79)

Add dispatch queue to DictionaryStorageProvider

.github/workflows/build.yml

@@ -11,5 +11,9 @@ jobs:
       - uses: actions/checkout@v2
       - name: Build
         run: swift build
+  test:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v2
       - name: Run tests
-        run: swift test
+        run: swift test --sanitize=thread

README.md

@@ -184,3 +184,13 @@ Once that succeeds, you can do the actual release:
 ```sh
 pod trunk push UnleashProxyClientSwift.podspec --allow-warnings
 ```
+
+## Testing
+
+In order to test this package you can run the swift test command. To test thread safety, run swift test with:
+
+```
+swift test --sanitize=thread
+```
+
+This will give you warnings in the console when you have any data races.

Sources/UnleashProxyClientSwift/Poller.swift

@@ -22,19 +22,26 @@ public protocol StorageProvider {
 
 public class DictionaryStorageProvider: StorageProvider {
     private var storage: [String: Toggle] = [:]
+    private let queue = DispatchQueue(label: "com.unleash.storageprovider")
 
     public init() {}
 
     public func set(value: Toggle?, key: String) {
-        storage[key] = value
+        queue.async {
+            self.storage[key] = value
+        }
     }
 
     public func value(key: String) -> Toggle? {
-        return storage[key]
+        queue.sync {
+            return self.storage[key]
+        }
     }
 
     public func clear() {
-        storage = [:]
+        queue.sync {
+            self.storage = [:]
+        }
     }
 }
 

Tests/UnleashProxyClientSwiftTests/UnleashClientIntegrationTest.swift

@@ -45,6 +45,13 @@ class UnleashIntegrationTests: XCTestCase {
         });
 
         unleashClient.start()
+        // Run isEnabled many times to trigger a data race when the poller is updating the data cache
+        // This is to test that the poller is thread safe, and you can verify this by running the test with
+        // swift test --sanitize=thread
+        for _ in 1...15000 {
+            let result = unleashClient.isEnabled(name: "dataRaceTest")
+            XCTAssertFalse(result)
+        }
 
         wait(for: [expectation], timeout: 5)
     }

UnleashProxyClientSwift.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |spec|
 spec.name         = "UnleashProxyClientSwift"
-spec.version      = "1.1.0"
+spec.version      = "1.1.1"
 spec.summary      = "Allows frontend clients to talk to unleash through the unleash edge, frontend API or the (deprecated) unleash proxy"
 spec.homepage     = "https://www.getunleash.io"
 spec.license      = { :type => "MIT", :file => "LICENSE" }