#1893 fix ensuring the consistency when doing signal enrichment

internal/models/signalenrichment/src/main/java/org/eclipse/ditto/internal/models/signalenrichment/CachingSignalEnrichmentFacade.java

@@ -38,11 +38,11 @@ public interface CachingSignalEnrichmentFacade extends SignalEnrichmentFacade {
      *
      * @param thingId the thing to retrieve.
      * @param events received thing events to reduce traffic. If there are no events, a fresh entry is retrieved.
-     * @param minAcceptableSeqNr the minimum sequence number acceptable as result. If negative,
+     * @param atRevisionNumber the revision/sequence number to retrieve the thing at. If negative,
      * cache loading is forced.
      * @return future of the retrieved thing.
      */
-    CompletionStage<JsonObject> retrieveThing(ThingId thingId, List<ThingEvent<?>> events, long minAcceptableSeqNr);
+    CompletionStage<JsonObject> retrieveThing(ThingId thingId, List<ThingEvent<?>> events, long atRevisionNumber);
 
     default JsonObject applyJsonFieldSelector(final JsonObject jsonObject,
             @Nullable final JsonFieldSelector fieldSelector) {

internal/models/signalenrichment/src/main/java/org/eclipse/ditto/internal/models/signalenrichment/DittoCachingSignalEnrichmentFacade.java

@@ -17,6 +17,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
+import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.concurrent.Executor;
@@ -25,7 +26,9 @@
 import javax.annotation.Nullable;
 
 import org.eclipse.ditto.base.model.entity.id.EntityId;
+import org.eclipse.ditto.base.model.headers.DittoHeaderDefinition;
 import org.eclipse.ditto.base.model.headers.DittoHeaders;
+import org.eclipse.ditto.base.model.headers.DittoHeadersBuilder;
 import org.eclipse.ditto.base.model.signals.Signal;
 import org.eclipse.ditto.base.model.signals.WithResource;
 import org.eclipse.ditto.internal.utils.cache.Cache;
@@ -54,7 +57,8 @@
  */
 public class DittoCachingSignalEnrichmentFacade implements CachingSignalEnrichmentFacade {
 
-    private static final ThreadSafeDittoLogger LOGGER = DittoLoggerFactory.getThreadSafeLogger(DittoCachingSignalEnrichmentFacade.class);
+    private static final ThreadSafeDittoLogger LOGGER =
+            DittoLoggerFactory.getThreadSafeLogger(DittoCachingSignalEnrichmentFacade.class);
     private static final String CACHE_NAME_SUFFIX = "_signal_enrichment_cache";
 
     protected final Cache<SignalEnrichmentCacheKey, JsonObject> extraFieldsCache;
@@ -93,23 +97,45 @@ public static DittoCachingSignalEnrichmentFacade newInstance(final SignalEnrichm
 
     @Override
     public CompletionStage<JsonObject> retrieveThing(final ThingId thingId, final List<ThingEvent<?>> events,
-            final long minAcceptableSeqNr) {
+            final long atRevisionNumber) {
 
-        final DittoHeaders dittoHeaders = DittoHeaders.empty();
+        final DittoHeaders dittoHeadersNotAddedToCacheKey =
+                buildDittoHeadersNotAddedToCacheKey(events, atRevisionNumber);
 
         final JsonFieldSelector fieldSelector = determineSelector(thingId.getNamespace());
 
-        if (minAcceptableSeqNr < 0) {
-            final var cacheKey =
-                    SignalEnrichmentCacheKey.of(thingId, SignalEnrichmentContext.of(dittoHeaders, fieldSelector));
+        if (atRevisionNumber < 0) {
+            final var cacheKey = SignalEnrichmentCacheKey.of(
+                    thingId,
+                    SignalEnrichmentContext.of(DittoHeaders.empty(), dittoHeadersNotAddedToCacheKey, fieldSelector));
             extraFieldsCache.invalidate(cacheKey);
-            return doCacheLookup(cacheKey, dittoHeaders);
+            return doCacheLookup(cacheKey, dittoHeadersNotAddedToCacheKey);
         } else {
             final var cachingParameters =
-                    new CachingParameters(fieldSelector, events, false, minAcceptableSeqNr);
+                    new CachingParameters(fieldSelector, events, false, atRevisionNumber);
 
-            return doRetrievePartialThing(thingId, dittoHeaders, cachingParameters);
+            return doRetrievePartialThing(thingId, DittoHeaders.empty(), dittoHeadersNotAddedToCacheKey,
+                    cachingParameters);
+        }
+    }
+
+    private static DittoHeaders buildDittoHeadersNotAddedToCacheKey(final List<ThingEvent<?>> events,
+            final long atRevisionNumber) {
+        final DittoHeadersBuilder<?, ?> dittoHeadersBuilder = DittoHeaders.newBuilder();
+        if (!events.isEmpty()) {
+            dittoHeadersBuilder.correlationId(
+                    events.get(events.size() - 1)
+                            .getDittoHeaders()
+                            .getCorrelationId()
+                            .orElseGet(() -> UUID.randomUUID().toString())
+                            + "-enrichment"
+            );
         }
+        if (atRevisionNumber > 0) {
+            dittoHeadersBuilder
+                    .putHeader(DittoHeaderDefinition.AT_HISTORICAL_REVISION.getKey(), String.valueOf(atRevisionNumber));
+        }
+        return dittoHeadersBuilder.build();
     }
 
     @Override
@@ -125,7 +151,7 @@ public CompletionStage<JsonObject> retrievePartialThing(final ThingId thingId,
         final var cachingParameters =
                 new CachingParameters(jsonFieldSelector, thingEvents, true, 0);
 
-        return doRetrievePartialThing(thingId, dittoHeaders, cachingParameters)
+        return doRetrievePartialThing(thingId, dittoHeaders, null, cachingParameters)
                 .thenApply(jsonObject -> applyJsonFieldSelector(jsonObject, jsonFieldSelector));
     }
 
@@ -140,7 +166,7 @@ public CompletionStage<JsonObject> retrievePartialThing(final ThingId thingId,
      * @param minAcceptableSeqNr minimum sequence number of the concerned signals to not invalidate the cache.
      * @return future that completes with the parts of a thing or fails with an error.
      */
-    @SuppressWarnings("java:S1612")
+    @SuppressWarnings({"java:S1612", "unused"})
     public CompletionStage<JsonObject> retrievePartialThing(final EntityId thingId,
             final JsonFieldSelector jsonFieldSelector,
             final DittoHeaders dittoHeaders,
@@ -156,19 +182,22 @@ public CompletionStage<JsonObject> retrievePartialThing(final EntityId thingId,
         final var cachingParameters =
                 new CachingParameters(jsonFieldSelector, thingEvents, true, minAcceptableSeqNr);
 
-        return doRetrievePartialThing(thingId, dittoHeaders, cachingParameters)
+        return doRetrievePartialThing(thingId, dittoHeaders, null, cachingParameters)
                 .thenApply(jsonObject -> applyJsonFieldSelector(jsonObject, jsonFieldSelector));
     }
 
     protected CompletionStage<JsonObject> doRetrievePartialThing(final EntityId thingId,
-                                                                 final DittoHeaders dittoHeaders,
-                                                                 final CachingParameters cachingParameters) {
+            final DittoHeaders dittoHeaders,
+            @Nullable final DittoHeaders dittoHeadersNotAddedToCacheKey,
+            final CachingParameters cachingParameters) {
 
         final var fieldSelector = cachingParameters.fieldSelector;
         final JsonFieldSelector enhancedFieldSelector = enhanceFieldSelectorWithRevision(fieldSelector);
 
-        final var idWithResourceType =
-                SignalEnrichmentCacheKey.of(thingId, SignalEnrichmentContext.of(dittoHeaders, enhancedFieldSelector));
+        final var idWithResourceType = SignalEnrichmentCacheKey.of(
+                thingId,
+                SignalEnrichmentContext.of(dittoHeaders, dittoHeadersNotAddedToCacheKey, enhancedFieldSelector)
+        );
 
         final var cachingParametersWithEnhancedFieldSelector = new CachingParameters(enhancedFieldSelector,
                 cachingParameters.concernedEvents,
@@ -282,7 +311,7 @@ private static DittoHeaders getLastDittoHeaders(final List<? extends Signal<?>>
     }
 
     protected CompletableFuture<JsonObject> doCacheLookup(final SignalEnrichmentCacheKey cacheKey,
-                                                          final DittoHeaders dittoHeaders) {
+            final DittoHeaders dittoHeaders) {
         LOGGER.withCorrelationId(dittoHeaders).debug("Looking up cache entry for <{}>", cacheKey);
 
         return extraFieldsCache.get(cacheKey)
@@ -343,16 +372,11 @@ private CompletionStage<JsonObject> handleNextExpectedThingEvents(final SignalEn
         JsonObject jsonObject = cachedJsonObject;
         for (final ThingEvent<?> thingEvent : concernedSignals) {
 
-            switch (thingEvent.getCommandCategory()) {
-                case MERGE:
-                    jsonObject = getMergeJsonObject(jsonObject, thingEvent);
-                    break;
-                case DELETE:
-                    jsonObject = getDeleteJsonObject(jsonObject, thingEvent);
-                    break;
-                default:
-                    jsonObject = getDefaultJsonObject(jsonObject, thingEvent);
-            }
+            jsonObject = switch (thingEvent.getCommandCategory()) {
+                case MERGE -> getMergeJsonObject(jsonObject, thingEvent);
+                case DELETE -> getDeleteJsonObject(jsonObject, thingEvent);
+                default -> getDefaultJsonObject(jsonObject, thingEvent);
+            };
             // invalidate cache on policy change if the flag is set
             if (cachingParameters.invalidateCacheOnPolicyChange) {
                 final var optionalCompletionStage =
@@ -392,7 +416,8 @@ private static JsonObject getDeleteJsonObject(final JsonObject jsonObject, final
         } else if (resourcePath.isEmpty()) {
             result = JsonObject.empty();
         } else {
-            result = jsonObject.remove(resourcePath).remove(Thing.JsonFields.METADATA.getPointer().append(resourcePath));
+            result =
+                    jsonObject.remove(resourcePath).remove(Thing.JsonFields.METADATA.getPointer().append(resourcePath));
         }
 
         return result;
@@ -463,9 +488,9 @@ protected static final class CachingParameters {
         private final long minAcceptableSeqNr;
 
         public CachingParameters(@Nullable final JsonFieldSelector fieldSelector,
-                                 final List<ThingEvent<?>> concernedEvents,
-                                 final boolean invalidateCacheOnPolicyChange,
-                                 final long minAcceptableSeqNr) {
+                final List<ThingEvent<?>> concernedEvents,
+                final boolean invalidateCacheOnPolicyChange,
+                final long minAcceptableSeqNr) {
 
             this.fieldSelector = fieldSelector;
             this.concernedEvents = concernedEvents;

internal/models/signalenrichment/src/main/java/org/eclipse/ditto/internal/models/signalenrichment/SignalEnrichmentCacheKey.java

@@ -27,7 +27,7 @@
  * Implementation for a {@link CacheKey} used in scope of signal enrichment.
  */
 @Immutable
-final class SignalEnrichmentCacheKey implements CacheKey<SignalEnrichmentContext> {
+public final class SignalEnrichmentCacheKey implements CacheKey<SignalEnrichmentContext> {
 
     static final String DELIMITER = ":";
 
@@ -63,8 +63,7 @@ public Optional<SignalEnrichmentContext> getCacheLookupContext() {
 
     @Override
     public boolean equals(@Nullable final Object o) {
-        if (o instanceof SignalEnrichmentCacheKey) {
-            final var that = (SignalEnrichmentCacheKey) o;
+        if (o instanceof SignalEnrichmentCacheKey that) {
             return isIdEqualValueBased(that) && Objects.equals(context, that.context);
         } else {
             return false;

internal/models/signalenrichment/src/main/java/org/eclipse/ditto/internal/models/signalenrichment/SignalEnrichmentCacheLoader.java

@@ -56,7 +56,10 @@ public CompletableFuture<JsonObject> asyncLoad(final SignalEnrichmentCacheKey ke
             final ThingId thingId = ThingId.of(key.getId());
             final JsonFieldSelector jsonFieldSelector = selectorOptional.orElse(null);
             final DittoHeaders dittoHeaders = context.getDittoHeaders();
-            return facade.retrievePartialThing(thingId, jsonFieldSelector, dittoHeaders, null)
+            final DittoHeaders retrieveHeaders = context.getDittoHeadersNotAddedToCacheKey()
+                    .map(extraHeaders -> (DittoHeaders) dittoHeaders.toBuilder().putHeaders(extraHeaders).build())
+                    .orElse(dittoHeaders);
+            return facade.retrievePartialThing(thingId, jsonFieldSelector, retrieveHeaders, null)
                     .toCompletableFuture();
         } else {
             // no context; nothing to load.

internal/models/signalenrichment/src/main/java/org/eclipse/ditto/internal/models/signalenrichment/SignalEnrichmentContext.java

@@ -29,29 +29,36 @@
  * signal enrichment caching.
  */
 @Immutable
-final class SignalEnrichmentContext implements CacheLookupContext {
+public final class SignalEnrichmentContext implements CacheLookupContext {
 
     private final DittoHeaders dittoHeaders;
+    @Nullable private final DittoHeaders dittoHeadersNotAddedToCacheKey;
     @Nullable private final JsonFieldSelector jsonFieldSelector;
 
     private SignalEnrichmentContext(final DittoHeaders dittoHeaders,
+            @Nullable final DittoHeaders dittoHeadersNotAddedToCacheKey,
             @Nullable final JsonFieldSelector jsonFieldSelector) {
         this.dittoHeaders = checkNotNull(dittoHeaders, "dittoHeaders");
+        this.dittoHeadersNotAddedToCacheKey = dittoHeadersNotAddedToCacheKey;
         this.jsonFieldSelector = jsonFieldSelector;
     }
 
     /**
-     * Creates a new SignalEnrichmentContext from the passed optional {@code dittoHeaders} and {@code jsonFieldSelector}
-     * retaining the for caching relevant {@code dittoHeaders} from the passed ones.
+     * Creates a new SignalEnrichmentContext from the passed optional {@code dittoHeaders},
+     * {@code dittoHeadersNotAddedToCacheKey} and {@code jsonFieldSelector}
+     * retaining the for caching relevant {@code dittoHeaders} from the passed ones, but not adding the
+     * {@code dittoHeadersNotAddedToCacheKey} to hashCode/equals, ignoring those for caching.
      *
      * @param dittoHeaders the DittoHeaders to use as key in the cache lookup context.
+     * @param dittoHeadersNotAddedToCacheKey the DittoHeaders to additionally use, but not include in the cache key.
      * @param jsonFieldSelector the JsonFieldSelector to use in the cache lookup context.
      * @return the created context.
      */
     static SignalEnrichmentContext of(final DittoHeaders dittoHeaders,
+            @Nullable final DittoHeaders dittoHeadersNotAddedToCacheKey,
             @Nullable final JsonFieldSelector jsonFieldSelector) {
 
-        return new SignalEnrichmentContext(dittoHeaders, jsonFieldSelector);
+        return new SignalEnrichmentContext(dittoHeaders, dittoHeadersNotAddedToCacheKey, jsonFieldSelector);
     }
 
     /**
@@ -63,6 +70,14 @@ public DittoHeaders getDittoHeaders() {
         return dittoHeaders;
     }
 
+    /**
+     * @return the additional DittoHeaders to use, e.g. for looking up the cache entry, but which are not part of the
+     * cache key.
+     */
+    public Optional<DittoHeaders> getDittoHeadersNotAddedToCacheKey() {
+        return Optional.ofNullable(dittoHeadersNotAddedToCacheKey);
+    }
+
     /**
      * Returns the optional JsonFieldSelector this context provides.
      *
@@ -94,6 +109,7 @@ public int hashCode() {
     public String toString() {
         return getClass().getSimpleName() + " [" +
                 "dittoHeaders=" + dittoHeaders +
+                ", dittoHeadersNotAddedToCacheKey=" + dittoHeadersNotAddedToCacheKey +
                 ", jsonFieldSelector=" + jsonFieldSelector +
                 "]";
     }