Fix some global kernel hooks not being executed

aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/chatcompletion/OpenAIChatCompletion.java

@@ -311,6 +311,7 @@ private Mono<ChatMessages> internalChatMessageContentsAsync(
 
         ChatCompletionsOptions options = executeHook(
             invocationContext,
+            kernel,
             new PreChatCompletionEvent(
                 getCompletionsOptions(
                     this,
@@ -349,7 +350,7 @@ private Mono<ChatMessages> internalChatMessageContentsAsync(
                     .collect(Collectors.toList());
 
                 // execute post chat completion hook
-                executeHook(invocationContext, new PostChatCompletionEvent(completions));
+                executeHook(invocationContext, kernel, new PostChatCompletionEvent(completions));
 
                 // Just return the result:
                 // If we don't want to attempt to invoke any functions
@@ -517,11 +518,12 @@ private Mono<FunctionResult<String>> invokeFunctionTool(
                 pluginName,
                 openAIFunctionToolCall.getFunctionName());
 
-            PreToolCallEvent hookResult = executeHook(invocationContext, new PreToolCallEvent(
-                openAIFunctionToolCall.getFunctionName(),
-                openAIFunctionToolCall.getArguments(),
-                function,
-                contextVariableTypes));
+            PreToolCallEvent hookResult = executeHook(invocationContext, kernel,
+                new PreToolCallEvent(
+                    openAIFunctionToolCall.getFunctionName(),
+                    openAIFunctionToolCall.getArguments(),
+                    function,
+                    contextVariableTypes));
 
             function = hookResult.getFunction();
             KernelFunctionArguments arguments = hookResult.getArguments();
@@ -537,12 +539,21 @@ private Mono<FunctionResult<String>> invokeFunctionTool(
 
     private static <T extends KernelHookEvent> T executeHook(
         @Nullable InvocationContext invocationContext,
+        @Nullable Kernel kernel,
         T event) {
-        KernelHooks kernelHooks = invocationContext != null
-            && invocationContext.getKernelHooks() != null
-                ? invocationContext.getKernelHooks()
-                : new KernelHooks();
-
+        KernelHooks kernelHooks = null;
+        if (kernel == null) {
+            if (invocationContext != null) {
+                kernelHooks = invocationContext.getKernelHooks();
+            }
+        } else {
+            kernelHooks = KernelHooks.merge(
+                kernel.getGlobalKernelHooks(),
+                invocationContext != null ? invocationContext.getKernelHooks() : null);
+        }
+        if (kernelHooks == null) {
+            return event;
+        }
         return kernelHooks.executeHooks(event);
     }
 

samples/semantickernel-concepts/semantickernel-syntax-examples/src/main/java/com/microsoft/semantickernel/samples/demos/lights/App.java

@@ -10,6 +10,7 @@
 import com.microsoft.semantickernel.aiservices.openai.chatcompletion.OpenAIChatCompletion;
 import com.microsoft.semantickernel.contextvariables.ContextVariableTypeConverter;
 import com.microsoft.semantickernel.contextvariables.ContextVariableTypes;
+import com.microsoft.semantickernel.hooks.KernelHooks;
 import com.microsoft.semantickernel.orchestration.InvocationContext;
 import com.microsoft.semantickernel.orchestration.InvocationContext.Builder;
 import com.microsoft.semantickernel.orchestration.InvocationReturnMode;
@@ -73,6 +74,27 @@ public static void main(String[] args) throws Exception {
                 .toPromptString(new Gson()::toJson)
                 .build());
 
+        KernelHooks hook = new KernelHooks();
+
+        hook.addPreToolCallHook((context) -> {
+            System.out.println("Pre-tool call hook");
+            return context;
+        });
+
+        hook.addPreChatCompletionHook(
+            (context) -> {
+                System.out.println("Pre-chat completion hook");
+                return context;
+            });
+
+        hook.addPostChatCompletionHook(
+            (context) -> {
+                System.out.println("Post-chat completion hook");
+                return context;
+            });
+
+        kernel.getGlobalKernelHooks().addHooks(hook);
+
         // Enable planning
         InvocationContext invocationContext = new Builder()
             .withReturnMode(InvocationReturnMode.LAST_MESSAGE_ONLY)

samples/semantickernel-concepts/semantickernel-syntax-examples/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/memory/InMemory_DataStorage.java

@@ -105,7 +105,8 @@ public static void main(String[] args) {
         inMemoryDataStorage(embeddingGeneration);
     }
 
-    public static void inMemoryDataStorage(OpenAITextEmbeddingGenerationService embeddingGeneration) {
+    public static void inMemoryDataStorage(
+        OpenAITextEmbeddingGenerationService embeddingGeneration) {
         // Create a new Volatile vector store
         var volatileVectorStore = new VolatileVectorStore();
 

semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/KernelHooks.java

@@ -66,7 +66,7 @@ public UnmodifiableKernelHooks unmodifiableClone() {
      *
      * @return an unmodifiable map of the hooks
      */
-    private Map<String, KernelHook<?>> getHooks() {
+    protected Map<String, KernelHook<?>> getHooks() {
         return Collections.unmodifiableMap(hooks);
     }
 
@@ -224,6 +224,31 @@ public boolean isEmpty() {
         return hooks.isEmpty();
     }
 
+    /**
+     * Builds the list of hooks to be invoked for the given context, by merging the hooks in this
+     * collection with the hooks in the context. Duplicate hooks in b will override hooks in a.
+     *
+     * @param a hooks to merge
+     * @param b hooks to merge
+     * @return the list of hooks to be invoked
+     */
+    public static KernelHooks merge(@Nullable KernelHooks a, @Nullable KernelHooks b) {
+        KernelHooks hooks = a;
+        if (hooks == null) {
+            hooks = new KernelHooks();
+        }
+
+        if (b == null) {
+            return hooks;
+        } else if (hooks.isEmpty()) {
+            return b;
+        } else {
+            HashMap<String, KernelHook<?>> merged = new HashMap<>(hooks.getHooks());
+            merged.putAll(b.getHooks());
+            return new KernelHooks(merged);
+        }
+    }
+
     /**
      * A wrapper for KernelHooks that disables mutating methods.
      */

semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelFunctionFromMethod.java

@@ -157,10 +157,9 @@ public static <T> ImplementationFunc<T> getFunction(Method method, Object instan
             }
 
             // kernelHooks must be effectively final for lambda
-            KernelHooks kernelHooks = context.getKernelHooks() != null
-                ? context.getKernelHooks()
-                : kernel.getGlobalKernelHooks();
-            assert kernelHooks != null : "getGlobalKernelHooks() should never return null!";
+            KernelHooks kernelHooks = KernelHooks.merge(
+                kernel.getGlobalKernelHooks(),
+                context.getKernelHooks());
 
             FunctionInvokingEvent updatedState = kernelHooks
                 .executeHooks(

semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelFunctionFromPrompt.java

@@ -102,10 +102,9 @@ private Flux<FunctionResult<T>> invokeInternalAsync(
             : InvocationContext.builder().build();
 
         // must be effectively final for lambda
-        KernelHooks kernelHooks = context.getKernelHooks() != null
-            ? context.getKernelHooks()
-            : kernel.getGlobalKernelHooks();
-        assert kernelHooks != null : "getGlobalKernelHooks() should never return null";
+        KernelHooks kernelHooks = KernelHooks.merge(
+            kernel.getGlobalKernelHooks(),
+            context.getKernelHooks());
 
         PromptRenderingEvent preRenderingHookResult = kernelHooks
             .executeHooks(new PromptRenderingEvent(this, argumentsIn));