use concurrent data structure for hooks

Signed-off-by: christian.lutnik <[email protected]>

Author: chrfwow

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

@@ -5,10 +5,11 @@
 import dev.openfeature.sdk.internal.AutoCloseableReentrantReadWriteLock;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
+import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import lombok.extern.slf4j.Slf4j;
@@ -23,14 +24,14 @@
 public class OpenFeatureAPI implements EventBus<OpenFeatureAPI> {
     // package-private multi-read/single-write lock
     static AutoCloseableReentrantReadWriteLock lock = new AutoCloseableReentrantReadWriteLock();
-    private final List<Hook> apiHooks;
+    private final ConcurrentLinkedQueue<Hook> apiHooks;
     private ProviderRepository providerRepository;
     private EventSupport eventSupport;
     private final AtomicReference<EvaluationContext> evaluationContext = new AtomicReference<>();
     private TransactionContextPropagator transactionContextPropagator;
 
     protected OpenFeatureAPI() {
-        apiHooks = new ArrayList<>();
+        apiHooks = new ConcurrentLinkedQueue<>();
         providerRepository = new ProviderRepository(this);
         eventSupport = new EventSupport();
         transactionContextPropagator = new NoOpTransactionContextPropagator();
@@ -303,9 +304,7 @@ public FeatureProvider getProvider(String domain) {
      * @param hooks The hook to add.
      */
     public void addHooks(Hook... hooks) {
-        try (AutoCloseableLock ignored = lock.writeLockAutoCloseable()) {
-            this.apiHooks.addAll(Arrays.asList(hooks));
-        }
+        this.apiHooks.addAll(Arrays.asList(hooks));
     }
 
     /**
@@ -314,22 +313,23 @@ public void addHooks(Hook... hooks) {
      * @return A list of {@link Hook}s.
      */
     public List<Hook> getHooks() {
-        try (AutoCloseableLock ignored = lock.readLockAutoCloseable()) {
-            if (this.apiHooks.isEmpty()) {
-                return Collections.emptyList();
-            } else {
-                return new ArrayList<>(this.apiHooks);
-            }
-        }
+        return new ArrayList<>(this.apiHooks);
+    }
+
+    /**
+     * Returns a reference to the collection of {@link Hook}s.
+     *
+     * @return The collection of {@link Hook}s.
+     */
+    Collection<Hook> getMutableHooks() {
+        return this.apiHooks;
     }
 
     /**
      * Removes all hooks.
      */
     public void clearHooks() {
-        try (AutoCloseableLock ignored = lock.writeLockAutoCloseable()) {
-            this.apiHooks.clear();
-        }
+        this.apiHooks.clear();
     }
 
     /**

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

@@ -5,8 +5,6 @@
 import dev.openfeature.sdk.exceptions.GeneralError;
 import dev.openfeature.sdk.exceptions.OpenFeatureError;
 import dev.openfeature.sdk.exceptions.ProviderNotReadyError;
-import dev.openfeature.sdk.internal.AutoCloseableLock;
-import dev.openfeature.sdk.internal.AutoCloseableReentrantReadWriteLock;
 import dev.openfeature.sdk.internal.ObjectUtils;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.util.ArrayList;
@@ -16,6 +14,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import lombok.Getter;
@@ -48,9 +47,8 @@ public class OpenFeatureClient implements Client {
     @Getter
     private final String version;
 
-    private final List<Hook> clientHooks;
+    private final ConcurrentLinkedQueue<Hook> clientHooks;
     private final HookSupport hookSupport;
-    AutoCloseableReentrantReadWriteLock hooksLock = new AutoCloseableReentrantReadWriteLock();
     private final AtomicReference<EvaluationContext> evaluationContext = new AtomicReference<>();
 
     /**
@@ -69,7 +67,7 @@ public OpenFeatureClient(OpenFeatureAPI openFeatureAPI, String domain, String ve
         this.openfeatureApi = openFeatureAPI;
         this.domain = domain;
         this.version = version;
-        this.clientHooks = new ArrayList<>();
+        this.clientHooks = new ConcurrentLinkedQueue<>();
         this.hookSupport = new HookSupport();
     }
 
@@ -126,9 +124,7 @@ public void track(String trackingEventName, EvaluationContext context, TrackingE
      */
     @Override
     public OpenFeatureClient addHooks(Hook... hooks) {
-        try (AutoCloseableLock ignored = this.hooksLock.writeLockAutoCloseable()) {
-            this.clientHooks.addAll(Arrays.asList(hooks));
-        }
+        this.clientHooks.addAll(Arrays.asList(hooks));
         return this;
     }
 
@@ -137,13 +133,7 @@ public OpenFeatureClient addHooks(Hook... hooks) {
      */
     @Override
     public List<Hook> getHooks() {
-        try (AutoCloseableLock ignored = this.hooksLock.readLockAutoCloseable()) {
-            if (this.clientHooks.isEmpty()) {
-                return Collections.emptyList();
-            } else {
-                return new ArrayList<>(this.clientHooks);
-            }
-        }
+        return new ArrayList<>(this.clientHooks);
     }
 
     /**
@@ -183,10 +173,8 @@ private <T> FlagEvaluationDetails<T> evaluateFlag(
             var provider = stateManager.getProvider();
             var state = stateManager.getState();
 
-            try (AutoCloseableLock ignored = this.hooksLock.readLockAutoCloseable()) {
-                mergedHooks = ObjectUtils.merge(
-                        provider.getProviderHooks(), flagOptions.getHooks(), clientHooks, openfeatureApi.getHooks());
-            }
+            mergedHooks = ObjectUtils.merge(
+                    provider.getProviderHooks(), flagOptions.getHooks(), clientHooks, openfeatureApi.getMutableHooks());
 
             var mergedCtx = hookSupport.beforeHooks(
                     type,

src/main/java/dev/openfeature/sdk/internal/ObjectUtils.java

@@ -1,6 +1,7 @@
 package dev.openfeature.sdk.internal;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Supplier;
@@ -64,9 +65,9 @@ public static <T> T defaultIfNull(T source, Supplier<T> defaultValue) {
      * @return resulting object
      */
     @SafeVarargs
-    public static <T> List<T> merge(List<T>... sources) {
+    public static <T> List<T> merge(Collection<T>... sources) {
         List<T> merged = new ArrayList<>();
-        for (List<T> source : sources) {
+        for (Collection<T> source : sources) {
             merged.addAll(source);
         }
         return merged;