feat: add method to set provider and block during init

src/main/java/dev/openfeature/sdk/OpenFeatureAPI.java

@@ -100,11 +100,12 @@
     public void setProvider(FeatureProvider provider) {
         try (AutoCloseableLock __ = lock.writeLockAutoCloseable()) {
             providerRepository.setProvider(
-                    provider,
-                    (p) -> attachEventProvider(p),
-                    (p) -> emitReady(p),
-                    (p) -> detachEventProvider(p),
-                    (p, message) -> emitError(p, message));
+                provider,
+                (p) -> attachEventProvider(p),
+                (p) -> emitReady(p),
+                (p) -> detachEventProvider(p),
+                (p, message) -> emitError(p, message),
+                false);
         }
     }
 
@@ -117,11 +118,45 @@
     public void setProvider(String clientName, FeatureProvider provider) {
         try (AutoCloseableLock __ = lock.writeLockAutoCloseable()) {
             providerRepository.setProvider(clientName,
-                    provider,
-                    this::attachEventProvider,
-                    this::emitReady,
-                    this::detachEventProvider,
-                    this::emitError);
+                provider,
+                this::attachEventProvider,
+                this::emitReady,
+                this::detachEventProvider,
+                this::emitError,
+                false);
+        }
+    }
+
+    /**
+     * Set the default provider and wait for initialization to finish.
+     */
+    public void setProviderAndWait(FeatureProvider provider) {
+        try (AutoCloseableLock __ = lock.writeLockAutoCloseable()) {
+            providerRepository.setProvider(
+                provider,
+                (p) -> attachEventProvider(p),
+                (p) -> emitReady(p),
+                (p) -> detachEventProvider(p),
+                (p, message) -> emitError(p, message),
+                true);
+        }
+    }
+
+    /**
+     * Add a provider for a named client and wait for initialization to finish.
+     *
+     * @param clientName The name of the client.
+     * @param provider   The provider to set.
+     */
+    public void setProviderAndWait(String clientName, FeatureProvider provider) {
+        try (AutoCloseableLock __ = lock.writeLockAutoCloseable()) {
+            providerRepository.setProvider(clientName,
+                provider,
+                this::attachEventProvider,
+                this::emitReady,
+                this::detachEventProvider,
+                this::emitError,
+                true);
         }
     }
 

src/main/java/dev/openfeature/sdk/ProviderRepository.java

@@ -43,8 +43,8 @@ public FeatureProvider getProvider(String name) {
 
     public List<String> getClientNamesForProvider(FeatureProvider provider) {
         return providers.entrySet().stream()
-                .filter(entry -> entry.getValue().equals(provider))
-                .map(entry -> entry.getKey()).collect(Collectors.toList());
+            .filter(entry -> entry.getValue().equals(provider))
+            .map(entry -> entry.getKey()).collect(Collectors.toList());
     }
 
     public Set<String> getAllBoundClientNames() {
@@ -62,58 +62,76 @@ public void setProvider(FeatureProvider provider,
             Consumer<FeatureProvider> afterSet,
             Consumer<FeatureProvider> afterInit,
             Consumer<FeatureProvider> afterShutdown,
-            BiConsumer<FeatureProvider, String> afterError) {
+            BiConsumer<FeatureProvider, String> afterError,
+            boolean waitForInit) {
         if (provider == null) {
             throw new IllegalArgumentException("Provider cannot be null");
         }
-        initializeProvider(null, provider, afterSet, afterInit, afterShutdown, afterError);
+        prepareAndInitializeProvider(null, provider, afterSet, afterInit, afterShutdown, afterError, waitForInit);
     }
 
     /**
      * Add a provider for a named client.
      *
-     * @param clientName The name of the client.
-     * @param provider   The provider to set.
+     * @param clientName  The name of the client.
+     * @param provider    The provider to set.
+     * @param waitForInit When true, wait for initialization to finish, then returns.
+     *                    Otherwise, initialization happens in the background.
      */
     public void setProvider(String clientName,
-            FeatureProvider provider,
-            Consumer<FeatureProvider> afterSet,
-            Consumer<FeatureProvider> afterInit,
-            Consumer<FeatureProvider> afterShutdown,
-            BiConsumer<FeatureProvider, String> afterError) {
+             FeatureProvider provider,
+             Consumer<FeatureProvider> afterSet,
+             Consumer<FeatureProvider> afterInit,
+             Consumer<FeatureProvider> afterShutdown,
+             BiConsumer<FeatureProvider, String> afterError,
+             boolean waitForInit) {
         if (provider == null) {
             throw new IllegalArgumentException("Provider cannot be null");
         }
         if (clientName == null) {
             throw new IllegalArgumentException("clientName cannot be null");
         }
-        initializeProvider(clientName, provider, afterSet, afterInit, afterShutdown, afterError);
+        prepareAndInitializeProvider(clientName, provider, afterSet, afterInit, afterShutdown, afterError, waitForInit);
     }
 
-    private void initializeProvider(@Nullable String clientName,
-            FeatureProvider newProvider,
-            Consumer<FeatureProvider> afterSet,
-            Consumer<FeatureProvider> afterInit,
-            Consumer<FeatureProvider> afterShutdown,
-            BiConsumer<FeatureProvider, String> afterError) {
+    private void prepareAndInitializeProvider(@Nullable String clientName,
+              FeatureProvider newProvider,
+              Consumer<FeatureProvider> afterSet,
+              Consumer<FeatureProvider> afterInit,
+              Consumer<FeatureProvider> afterShutdown,
+              BiConsumer<FeatureProvider, String> afterError,
+              boolean waitForInit) {
+
         // provider is set immediately, on this thread
         FeatureProvider oldProvider = clientName != null
-                ? this.providers.put(clientName, newProvider)
-                : this.defaultProvider.getAndSet(newProvider);
+            ? this.providers.put(clientName, newProvider)
+            : this.defaultProvider.getAndSet(newProvider);
         afterSet.accept(newProvider);
-        taskExecutor.submit(() -> {
-            // initialization happens in a different thread
-            try {
-                if (ProviderState.NOT_READY.equals(newProvider.getState())) {
-                    newProvider.initialize(OpenFeatureAPI.getInstance().getEvaluationContext());
-                    afterInit.accept(newProvider);
-                }
-                shutDownOld(oldProvider, afterShutdown);
-            } catch (Exception e) {
-                log.error("Exception when initializing feature provider {}", newProvider.getClass().getName(), e);
-                afterError.accept(newProvider, e.getMessage());
+        if (waitForInit) {
+            initializeProvider(newProvider, afterInit, afterShutdown, afterError, oldProvider);
+        } else {
+            taskExecutor.submit(() -> {
+                // initialization happens in a different thread if we're not waiting it
+                initializeProvider(newProvider, afterInit, afterShutdown, afterError, oldProvider);
+            });
+        }
+    }
+
+    private void initializeProvider(FeatureProvider newProvider,
+            Consumer<FeatureProvider> afterInit,
+            Consumer<FeatureProvider> afterShutdown,
+            BiConsumer<FeatureProvider, String> afterError,
+            FeatureProvider oldProvider) {
+        try {
+            if (ProviderState.NOT_READY.equals(newProvider.getState())) {
+                newProvider.initialize(OpenFeatureAPI.getInstance().getEvaluationContext());
+                afterInit.accept(newProvider);
             }
-        });
+            shutDownOld(oldProvider, afterShutdown);
+        } catch (Exception e) {
+            log.error("Exception when initializing feature provider {}", newProvider.getClass().getName(), e);
+            afterError.accept(newProvider, e.getMessage());
+        }
     }
 
     private void shutDownOld(FeatureProvider oldProvider,Consumer<FeatureProvider> afterShutdown) {
@@ -157,7 +175,7 @@ public void shutdown() {
                 },
                 (FeatureProvider fp,
                         String message) -> {
-                });
+                }, false);
         this.providers.clear();
         taskExecutor.shutdown();
     }

src/test/java/dev/openfeature/sdk/FlagEvaluationSpecTest.java

@@ -17,6 +17,10 @@
 import java.util.List;
 import java.util.Map;
 
+import dev.openfeature.sdk.providers.memory.InMemoryProvider;
+import dev.openfeature.sdk.testutils.TestEventsProvider;
+import lombok.SneakyThrows;
+import org.awaitility.Awaitility;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -69,6 +73,34 @@ void getApiInstance() {
         assertThat(api.getProvider()).isEqualTo(mockProvider);
     }
 
+    @SneakyThrows
+    @Specification(number="1.1.8", text="The API SHOULD provide functions to set a provider and wait for the initialize function to return or throw.")
+    @Test void providerAndWait() {
+        FeatureProvider provider = new TestEventsProvider(500);
+        OpenFeatureAPI.getInstance().setProviderAndWait(provider);
+        assertThat(api.getProvider().getState()).isEqualTo(ProviderState.READY);
+
+        provider = new TestEventsProvider(500);
+        String providerName = "providerAndWait";
+        OpenFeatureAPI.getInstance().setProviderAndWait(providerName, provider);
+        assertThat(api.getProvider(providerName).getState()).isEqualTo(ProviderState.READY);
+    }
+
+    @Specification(number="2.4.5", text="The provider SHOULD indicate an error if flag resolution is attempted before the provider is ready.")
+    @Test void shouldReturnNotReadyIfNotInitialized() {
+        FeatureProvider provider = new InMemoryProvider(new HashMap<>()) {
+            @Override
+            public void initialize(EvaluationContext evaluationContext) throws Exception {
+                Awaitility.await().wait(3000);
+            }
+        };
+        String providerName = "shouldReturnNotReadyIfNotInitialized";
+        OpenFeatureAPI.getInstance().setProvider(providerName, provider);
+        assertThat(api.getProvider(providerName).getState()).isEqualTo(ProviderState.NOT_READY);
+        Client client = OpenFeatureAPI.getInstance().getClient(providerName);
+        assertEquals(ErrorCode.PROVIDER_NOT_READY, client.getBooleanDetails("return_error_when_not_initialized", false).getErrorCode());
+    }
+
     @Specification(number="1.1.5", text="The API MUST provide a function for retrieving the metadata field of the configured provider.")
     @Test void provider_metadata() {
         FeatureProviderTestUtils.setFeatureProvider(new DoSomethingProvider());
@@ -291,4 +323,5 @@ void getApiInstance() {
 
     @Specification(number="1.4.11", text="The client SHOULD provide asynchronous or non-blocking mechanisms for flag evaluation.")
     @Test void one_thread_per_request_model() {}
+
 }

src/test/java/dev/openfeature/sdk/ProviderRepositoryTest.java

@@ -55,7 +55,7 @@ class DefaultProvider {
             @DisplayName("should reject null as default provider")
             void shouldRejectNullAsDefaultProvider() {
                 assertThatCode(() -> providerRepository.setProvider(null, mockAfterSet(), mockAfterInit(),
-                        mockAfterShutdown(), mockAfterError())).isInstanceOf(IllegalArgumentException.class);
+                        mockAfterShutdown(), mockAfterError(), false)).isInstanceOf(IllegalArgumentException.class);
             }
 
             @Test
@@ -76,7 +76,7 @@ void shouldImmediatelyReturnWhenCallingTheProviderMutator() throws Exception {
                         .atMost(Duration.ofSeconds(1))
                         .until(() -> {
                             providerRepository.setProvider(featureProvider, mockAfterSet(), mockAfterInit(),
-                                    mockAfterShutdown(), mockAfterError());
+                                    mockAfterShutdown(), mockAfterError(), false);
                             verify(featureProvider, timeout(TIMEOUT)).initialize(any());
                             return true;
                         });
@@ -101,7 +101,7 @@ class NamedProvider {
             @DisplayName("should reject null as named provider")
             void shouldRejectNullAsNamedProvider() {
                 assertThatCode(() -> providerRepository.setProvider(CLIENT_NAME, null, mockAfterSet(), mockAfterInit(),
-                        mockAfterShutdown(), mockAfterError()))
+                        mockAfterShutdown(), mockAfterError(), false))
                         .isInstanceOf(IllegalArgumentException.class);
             }
 
@@ -110,7 +110,7 @@ void shouldRejectNullAsNamedProvider() {
             void shouldRejectNullAsDefaultProvider() {
                 NoOpProvider provider = new NoOpProvider();
                 assertThatCode(() -> providerRepository.setProvider(null, provider, mockAfterSet(), mockAfterInit(),
-                        mockAfterShutdown(), mockAfterError()))
+                        mockAfterShutdown(), mockAfterError(), false))
                         .isInstanceOf(IllegalArgumentException.class);
             }
 
@@ -126,7 +126,7 @@ void shouldImmediatelyReturnWhenCallingTheNamedClientProviderMutator() throws Ex
                         .atMost(Duration.ofSeconds(1))
                         .until(() -> {
                             providerRepository.setProvider("named client", featureProvider, mockAfterSet(),
-                                    mockAfterInit(), mockAfterShutdown(), mockAfterError());
+                                    mockAfterInit(), mockAfterShutdown(), mockAfterError(), false);
                             verify(featureProvider, timeout(TIMEOUT)).initialize(any());
                             return true;
                         });
@@ -161,7 +161,7 @@ void shouldImmediatelyReturnWhenCallingTheProviderMutator() throws Exception {
                         .atMost(Duration.ofSeconds(1))
                         .until(() -> {
                             providerRepository.setProvider(newProvider, mockAfterSet(), mockAfterInit(),
-                                    mockAfterShutdown(), mockAfterError());
+                                    mockAfterShutdown(), mockAfterError(), false);
                             verify(newProvider, timeout(TIMEOUT)).initialize(any());
                             return true;
                         });
@@ -194,7 +194,7 @@ void shouldImmediatelyReturnWhenCallingTheProviderMutator() throws Exception {
 
                 Future<?> providerMutation = executorService
                         .submit(() -> providerRepository.setProvider(CLIENT_NAME, newProvider, mockAfterSet(),
-                                mockAfterInit(), mockAfterShutdown(), mockAfterError()));
+                                mockAfterInit(), mockAfterShutdown(), mockAfterError(), false));
 
                 await()
                         .alias("wait for provider mutator to return")
@@ -311,7 +311,7 @@ void shouldShutdownAllFeatureProvidersOnShutdown() {
 
     private void setFeatureProvider(FeatureProvider provider) {
         providerRepository.setProvider(provider, mockAfterSet(), mockAfterInit(), mockAfterShutdown(),
-                mockAfterError());
+                mockAfterError(), false);
         waitForSettingProviderHasBeenCompleted(ProviderRepository::getProvider, provider);
     }
 
@@ -320,13 +320,13 @@ private void setFeatureProvider(FeatureProvider provider, Consumer<FeatureProvid
             Consumer<FeatureProvider> afterInit, Consumer<FeatureProvider> afterShutdown,
             BiConsumer<FeatureProvider, String> afterError) {
         providerRepository.setProvider(provider, afterSet, afterInit, afterShutdown,
-                afterError);
+                afterError, false);
         waitForSettingProviderHasBeenCompleted(ProviderRepository::getProvider, provider);
     }
 
     private void setFeatureProvider(String namedProvider, FeatureProvider provider) {
         providerRepository.setProvider(namedProvider, provider, mockAfterSet(), mockAfterInit(), mockAfterShutdown(),
-                mockAfterError());
+                mockAfterError(), false);
         waitForSettingProviderHasBeenCompleted(repository -> repository.getProvider(namedProvider), provider);
     }
 

src/test/java/dev/openfeature/sdk/e2e/StepDefinitions.java

@@ -56,11 +56,7 @@ public class StepDefinitions {
     public static void setup() {
         Map<String, Flag<?>> flags = buildFlags();
         InMemoryProvider provider = new InMemoryProvider(flags);
-        OpenFeatureAPI.getInstance().setProvider(provider);
-
-        // TODO: setProvider with wait for init, pending https://github.com/open-feature/ofep/pull/80
-        Thread.sleep(500);
-
+        OpenFeatureAPI.getInstance().setProviderAndWait(provider);
         client = OpenFeatureAPI.getInstance().getClient();
     }
 

src/test/java/dev/openfeature/sdk/providers/memory/InMemoryProviderTest.java

@@ -6,12 +6,13 @@
 import dev.openfeature.sdk.OpenFeatureAPI;
 import dev.openfeature.sdk.Value;
 import dev.openfeature.sdk.exceptions.FlagNotFoundError;
+import dev.openfeature.sdk.exceptions.ProviderNotReadyError;
 import dev.openfeature.sdk.exceptions.TypeMismatchError;
 import lombok.SneakyThrows;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
-import org.omg.CORBA.DynAnyPackage.TypeMismatch;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import static dev.openfeature.sdk.Structure.mapToStructure;
@@ -36,11 +37,7 @@ static void beforeAll() {
         Map<String, Flag<?>> flags = buildFlags();
         provider = spy(new InMemoryProvider(flags));
         OpenFeatureAPI.getInstance().onProviderConfigurationChanged(eventDetails -> {});
-        OpenFeatureAPI.getInstance().setProvider(provider);
-
-        // TODO: setProvider with wait for init, pending https://github.com/open-feature/ofep/pull/80
-        Thread.sleep(500);
-
+        OpenFeatureAPI.getInstance().setProviderAndWait(provider);
         client = OpenFeatureAPI.getInstance().getClient();
         provider.updateFlags(flags);
         provider.updateFlag("addedFlag", Flag.builder()
@@ -99,4 +96,13 @@ void typeMismatch() {
             provider.getBooleanEvaluation("string-flag", false, new ImmutableContext());
         });
     }
+
+    @SneakyThrows
+    @Test
+    void shouldThrowIfNotInitialized() {
+        InMemoryProvider inMemoryProvider = new InMemoryProvider(new HashMap<>());
+
+        // ErrorCode.PROVIDER_NOT_READY should be returned when evaluated via the client
+        assertThrows(ProviderNotReadyError.class, ()-> inMemoryProvider.getBooleanEvaluation("fail_not_initialized", false, new ImmutableContext()));
+    }
 }