feat: enhance OData observability and test utilities

datamodel/odata-client-apache-httpclient5/src/main/java/com/sap/cloud/sdk/datamodel/odata/client/request/ODataHttpRequest.java

@@ -4,6 +4,8 @@
 
 import java.io.IOException;
 import java.net.URI;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.function.Function;
 
 import javax.annotation.Nonnull;
@@ -104,11 +106,15 @@ private ClassicHttpResponse requestResource( @Nonnull final Function<URI, HttpUr
 
         odataRequest.getListeners().forEach(v -> v.listenOnRequest(httpRequest));
 
+        final Instant start = Instant.now();
         try {
-            return httpClient.executeOpen(null, httpRequest, null);
+            final ClassicHttpResponse response = httpClient.executeOpen(null, httpRequest, null);
+            odataRequest.getListeners().forEach(v -> v.listenOnResponse(response));
+            return response;
         }
         catch( final ClientProtocolException e ) {
             log.debug("Connection could not be established.", e);
+            odataRequest.getListeners().forEach(v -> v.listenOnRequestError(e));
             throw new ODataConnectionException(
                 this.odataRequest,
                 httpRequest,
@@ -117,6 +123,7 @@ private ClassicHttpResponse requestResource( @Nonnull final Function<URI, HttpUr
         }
         catch( final ConnectionRequestTimeoutException e ) {
             log.debug("Connection pool timed out.", e);
+            odataRequest.getListeners().forEach(v -> v.listenOnRequestError(e));
             throw new ODataConnectionException(this.odataRequest, httpRequest, """
                 Time out occurred because of a probable connection leak. Please execute your request \
                 with try-with-resources to ensure resources are properly closed. \
@@ -127,12 +134,18 @@ private ClassicHttpResponse requestResource( @Nonnull final Function<URI, HttpUr
         }
         catch( final IOException e ) {
             log.debug("Connection was aborted.", e);
+            odataRequest.getListeners().forEach(v -> v.listenOnRequestError(e));
             throw new ODataConnectionException(this.odataRequest, httpRequest, "Connection was aborted.", e);
         }
         catch( final Exception e ) {
             log.debug("Connection failed.", e);
+            odataRequest.getListeners().forEach(v -> v.listenOnRequestError(e));
             throw new ODataConnectionException(this.odataRequest, httpRequest, "Connection failed.", e);
         }
+        finally {
+            final Duration duration = Duration.between(start, Instant.now());
+            odataRequest.getListeners().forEach(v -> v.listenOnExecutionFinished(duration));
+        }
     }
 
     /**

datamodel/odata-client-apache-httpclient5/src/main/java/com/sap/cloud/sdk/datamodel/odata/client/request/ODataRequestGeneric.java

@@ -65,7 +65,6 @@ public abstract class ODataRequestGeneric implements ODataRequestExecutable
     /**
      * List of listeners to observe and react on OData actions.
      */
-    @Getter( AccessLevel.PROTECTED )
     private final List<ODataRequestListener> listeners = new ArrayList<>();
 
     /**
@@ -96,6 +95,18 @@ public abstract class ODataRequestGeneric implements ODataRequestExecutable
         headers.putIfAbsent(HttpHeaders.ACCEPT, Lists.newArrayList(DEFAULT_FORMAT.getHttpAccept()));
     }
 
+    /**
+     * Get the list of listeners to observe and react on OData actions.
+     *
+     * @return The list of listeners.
+     * @since 5.35.0
+     */
+    @Nonnull
+    public List<ODataRequestListener> getListeners()
+    {
+        return listeners;
+    }
+
     /**
      * Get the static request URI of the OData resource.
      *

datamodel/odata-client-apache-httpclient5/src/main/java/com/sap/cloud/sdk/datamodel/odata/client/request/ODataRequestListener.java

@@ -1,8 +1,11 @@
 package com.sap.cloud.sdk.datamodel.odata.client.request;
 
+import java.time.Duration;
+
 import javax.annotation.Nonnull;
 
 import org.apache.hc.client5.http.classic.methods.HttpUriRequestBase;
+import org.apache.hc.core5.http.ClassicHttpResponse;
 
 /**
  * Consumer class for the Listener Pattern to monitor and react on OData actions.
@@ -19,6 +22,28 @@ public interface ODataRequestListener
      */
     void listenOnRequest( @Nonnull final HttpUriRequestBase request );
 
+    /**
+     * Handler to react after execution of an HTTP request, when the response is received.
+     *
+     * @param response
+     *            The HTTP response.
+     * @since 5.35.0
+     */
+    default void listenOnResponse( @Nonnull final ClassicHttpResponse response )
+    {
+    }
+
+    /**
+     * Handler to react after the request execution has finished (either successfully or with an error).
+     *
+     * @param duration
+     *            The duration of the request execution.
+     * @since 5.35.0
+     */
+    default void listenOnExecutionFinished( @Nonnull final Duration duration )
+    {
+    }
+
     /**
      * Handler to react on an error during request generation.
      *

datamodel/odata-client-apache-httpclient5/src/main/java/com/sap/cloud/sdk/datamodel/odata/client/request/ODataRequestResultFactory.java

@@ -43,7 +43,12 @@ interface ODataRequestResultFactory
             .onEmpty(() -> log.debug("HTTP response entity is empty: {}", status))
             .map(entity -> Try.run(() -> copy.setEntity(new BufferedHttpEntity(entity))))
             .peek(b -> b.onSuccess(v -> log.debug("Successfully buffered the HTTP response entity.")))
-            .peek(b -> b.onFailure(e -> log.warn("Failed to buffer HTTP response entity: {}", status, e)));
+            .peek(b -> b.onFailure(t -> {
+                log.warn("Failed to buffer HTTP response entity: {}", status, t);
+                if( t instanceof Exception ) {
+                    oDataRequest.getListeners().forEach(l -> l.listenOnParsingError((Exception) t));
+                }
+            }));
 
         Try.run(httpResponse::close).onFailure(e -> log.warn("Failed to close HTTP response: {}", status, e));
 

datamodel/odata-client-apache-httpclient5/src/main/java/com/sap/cloud/sdk/datamodel/odata/client/request/ODataRequestResultGeneric.java

@@ -165,21 +165,27 @@ public void streamElements( @Nonnull final Consumer<ResultElement> handler )
     {
         final GsonResultElementFactory resultElementFactory = getResultElementFactory();
 
-        final Integer numConsumedElements = HttpEntityReader.stream(this, reader -> {
-            deserializer.positionReaderToResultSet(reader);
-
-            int count = 0;
-            while( reader.hasNext() && reader.peek() == JsonToken.BEGIN_OBJECT ) {
-                final JsonElement jsonElement = JsonParser.parseReader(reader);
-                final ResultElement resultElement = resultElementFactory.create(jsonElement);
-                handler.accept(resultElement);
-                count++;
-            }
-            reader.close();
-            return count;
-        });
-
-        log.debug("Iterated {} elements.", numConsumedElements);
+        try {
+            final Integer numConsumedElements = HttpEntityReader.stream(this, reader -> {
+                deserializer.positionReaderToResultSet(reader);
+
+                int count = 0;
+                while( reader.hasNext() && reader.peek() == JsonToken.BEGIN_OBJECT ) {
+                    final JsonElement jsonElement = JsonParser.parseReader(reader);
+                    final ResultElement resultElement = resultElementFactory.create(jsonElement);
+                    handler.accept(resultElement);
+                    count++;
+                }
+                reader.close();
+                return count;
+            });
+
+            log.debug("Iterated {} elements.", numConsumedElements);
+        }
+        catch( final Exception e ) {
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
+        }
     }
 
     private GsonResultElementFactory getResultElementFactory()
@@ -204,22 +210,32 @@ private ResultPrimitive loadPrimitiveFromResponse(
         @Nonnull final Function<JsonElement, JsonElement> jsonElementExtractor )
     {
         final GsonResultElementFactory elementFactory = getResultElementFactory();
-        final ResultPrimitive result = HttpEntityReader.read(this, element -> {
-            final Option<ResultPrimitive> single =
-                deserializer
-                    .getElementToResultPrimitiveSingle(element)
-                    .map(jsonElementExtractor)
-                    .map(elementFactory::create)
-                    .map(ResultElement::getAsPrimitive);
-            return single.getOrNull();
-        });
+        final ResultPrimitive result;
+        try {
+            result = HttpEntityReader.read(this, element -> {
+                final Option<ResultPrimitive> single =
+                    deserializer
+                        .getElementToResultPrimitiveSingle(element)
+                        .map(jsonElementExtractor)
+                        .map(elementFactory::create)
+                        .map(ResultElement::getAsPrimitive);
+                return single.getOrNull();
+            });
+        }
+        catch( final Exception e ) {
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
+        }
         if( result == null ) {
             log.debug("{} response cannot be read as a primitive value.", protocol);
-            throw new ODataDeserializationException(
-                getODataRequest(),
-                getHttpResponse(),
-                "Unable to read " + protocol + " response.",
-                null);
+            final ODataDeserializationException e =
+                new ODataDeserializationException(
+                    getODataRequest(),
+                    getHttpResponse(),
+                    "Unable to read " + protocol + " response.",
+                    null);
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
         }
         return result;
     }
@@ -229,21 +245,31 @@ private ResultCollection loadPrimitiveCollectionFromResponse()
     {
         final GsonResultElementFactory elementFactory = getResultElementFactory();
 
-        final ResultCollection result = HttpEntityReader.read(this, element -> {
-            final Option<ResultCollection> set =
-                deserializer
-                    .getElementToResultPrimitiveSet(element)
-                    .map(elementFactory::create)
-                    .map(ResultElement::getAsCollection);
-            return set.getOrNull();
-        });
+        final ResultCollection result;
+        try {
+            result = HttpEntityReader.read(this, element -> {
+                final Option<ResultCollection> set =
+                    deserializer
+                        .getElementToResultPrimitiveSet(element)
+                        .map(elementFactory::create)
+                        .map(ResultElement::getAsCollection);
+                return set.getOrNull();
+            });
+        }
+        catch( final Exception e ) {
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
+        }
         if( result == null ) {
             log.debug("{} response cannot be read as set of primitive values.", protocol);
-            throw new ODataDeserializationException(
-                getODataRequest(),
-                getHttpResponse(),
-                "Unable to read " + protocol + " response.",
-                null);
+            final ODataDeserializationException e =
+                new ODataDeserializationException(
+                    getODataRequest(),
+                    getHttpResponse(),
+                    "Unable to read " + protocol + " response.",
+                    null);
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
         }
         return result;
     }
@@ -252,22 +278,32 @@ private ResultCollection loadPrimitiveCollectionFromResponse()
     private ResultObject loadEntryFromResponse( @Nonnull final Function<JsonElement, JsonElement> jsonElementExtractor )
     {
         final GsonResultElementFactory elementFactory = getResultElementFactory();
-        final ResultObject result = HttpEntityReader.read(this, element -> {
-            final Option<ResultObject> single =
-                deserializer
-                    .getElementToResultSingle(element)
-                    .map(jsonElementExtractor)
-                    .map(elementFactory::create)
-                    .map(ResultElement::getAsObject);
-            return single.getOrNull();
-        });
+        final ResultObject result;
+        try {
+            result = HttpEntityReader.read(this, element -> {
+                final Option<ResultObject> single =
+                    deserializer
+                        .getElementToResultSingle(element)
+                        .map(jsonElementExtractor)
+                        .map(elementFactory::create)
+                        .map(ResultElement::getAsObject);
+                return single.getOrNull();
+            });
+        }
+        catch( final Exception e ) {
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
+        }
         if( result == null ) {
             log.debug("{} response cannot be read as a single entity.", protocol);
-            throw new ODataDeserializationException(
-                getODataRequest(),
-                getHttpResponse(),
-                "Unable to read " + protocol + " response.",
-                null);
+            final ODataDeserializationException e =
+                new ODataDeserializationException(
+                    getODataRequest(),
+                    getHttpResponse(),
+                    "Unable to read " + protocol + " response.",
+                    null);
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
         }
         return result;
     }
@@ -277,21 +313,31 @@ private ResultCollection loadEntryCollectionFromResponse()
     {
         final GsonResultElementFactory elementFactory = getResultElementFactory();
 
-        final ResultCollection result = HttpEntityReader.read(this, element -> {
-            final Option<ResultCollection> set =
-                deserializer
-                    .getElementToResultSet(element)
-                    .map(elementFactory::create)
-                    .map(ResultElement::getAsCollection);
-            return set.getOrNull();
-        });
+        final ResultCollection result;
+        try {
+            result = HttpEntityReader.read(this, element -> {
+                final Option<ResultCollection> set =
+                    deserializer
+                        .getElementToResultSet(element)
+                        .map(elementFactory::create)
+                        .map(ResultElement::getAsCollection);
+                return set.getOrNull();
+            });
+        }
+        catch( final Exception e ) {
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
+        }
         if( result == null ) {
             log.debug("{} response cannot be read as set of entities.", protocol);
-            throw new ODataDeserializationException(
-                getODataRequest(),
-                getHttpResponse(),
-                "Unable to read " + protocol + " response.",
-                null);
+            final ODataDeserializationException e =
+                new ODataDeserializationException(
+                    getODataRequest(),
+                    getHttpResponse(),
+                    "Unable to read " + protocol + " response.",
+                    null);
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
         }
         return result;
     }
@@ -690,11 +736,14 @@ public boolean hasPayload()
     private void assertNonEmptyPayload()
     {
         if( !hasPayload() ) {
-            throw new ODataDeserializationException(
-                getODataRequest(),
-                getHttpResponse(),
-                protocol + " response did not contain any payload.",
-                null);
+            final ODataDeserializationException e =
+                new ODataDeserializationException(
+                    getODataRequest(),
+                    getHttpResponse(),
+                    protocol + " response did not contain any payload.",
+                    null);
+            oDataRequest.getListeners().forEach(l -> l.listenOnParsingError(e));
+            throw e;
         }
     }