[GitHub] [kafka] aheyne commented on a diff in pull request #12644: KAFKA-14209 : Rewrite self joins to use single state store 2/3

[GitBox <gi...@apache.org>]

aheyne commented on code in PR #12644:
URL: https://github.com/apache/kafka/pull/12644#discussion_r978077841


##########
streams/src/main/java/org/apache/kafka/streams/kstream/internals/KStreamKStreamSelfJoin.java:
##########
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.streams.kstream.internals;
+
+import static org.apache.kafka.streams.processor.internals.metrics.TaskMetrics.droppedRecordsSensor;
+
+import org.apache.kafka.common.metrics.Sensor;
+import org.apache.kafka.streams.KeyValue;
+import org.apache.kafka.streams.kstream.ValueJoinerWithKey;
+import org.apache.kafka.streams.kstream.internals.KStreamImplJoin.TimeTracker;
+import org.apache.kafka.streams.processor.api.ContextualProcessor;
+import org.apache.kafka.streams.processor.api.Processor;
+import org.apache.kafka.streams.processor.api.ProcessorContext;
+import org.apache.kafka.streams.processor.api.ProcessorSupplier;
+import org.apache.kafka.streams.processor.api.Record;
+import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl;
+import org.apache.kafka.streams.state.WindowStore;
+import org.apache.kafka.streams.state.WindowStoreIterator;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class KStreamKStreamSelfJoin<K, V1, V2, VOut> implements ProcessorSupplier<K, V1, K, VOut> {
+    private static final Logger LOG = LoggerFactory.getLogger(KStreamKStreamSelfJoin.class);
+
+    private final String windowName;
+    private final long joinThisBeforeMs;
+    private final long joinThisAfterMs;
+    private final long joinOtherBeforeMs;
+    private final long joinOtherAfterMs;
+    private final ValueJoinerWithKey<? super K, ? super V1, ? super V2, ? extends VOut> joinerThis;
+
+    private final TimeTracker sharedTimeTracker;
+
+    KStreamKStreamSelfJoin(
+        final String windowName,
+        final JoinWindowsInternal windows,
+        final ValueJoinerWithKey<? super K, ? super V1, ? super V2, ? extends VOut> joinerThis,
+        final TimeTracker sharedTimeTracker) {
+
+        this.windowName = windowName;
+        this.joinThisBeforeMs = windows.beforeMs;
+        this.joinThisAfterMs = windows.afterMs;
+        this.joinOtherBeforeMs = windows.afterMs;
+        this.joinOtherAfterMs = windows.beforeMs;
+        this.joinerThis = joinerThis;
+        this.sharedTimeTracker = sharedTimeTracker;
+    }
+
+    @Override
+    public Processor<K, V1, K, VOut> get() {
+        return new KStreamKStreamSelfJoinProcessor();
+    }
+
+    private class KStreamKStreamSelfJoinProcessor extends ContextualProcessor<K, V1, K, VOut> {
+        private WindowStore<K, V2> windowStore;
+        private Sensor droppedRecordsSensor;
+
+        @Override
+        public void init(final ProcessorContext<K, VOut> context) {
+            super.init(context);
+
+            final StreamsMetricsImpl metrics = (StreamsMetricsImpl) context.metrics();
+            droppedRecordsSensor = droppedRecordsSensor(Thread.currentThread().getName(), context.taskId().toString(), metrics);
+            windowStore = context.getStateStore(windowName);
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public void process(final Record<K, V1> record) {
+            if (StreamStreamJoinUtil.skipRecord(record, LOG, droppedRecordsSensor, context())) {
+                return;
+            }
+
+            final long inputRecordTimestamp = record.timestamp();
+            long timeFrom = Math.max(0L, inputRecordTimestamp - joinThisBeforeMs);
+            long timeTo = Math.max(0L, inputRecordTimestamp + joinThisAfterMs);
+            boolean emittedJoinWithSelf = false;
+            final Record selfRecord = record
+                .withValue(joinerThis.apply(record.key(), record.value(), (V2) record.value()))
+                .withTimestamp(inputRecordTimestamp);
+            sharedTimeTracker.advanceStreamTime(inputRecordTimestamp);
+
+            // Join current record with other
+            try (final WindowStoreIterator<V2> iter = windowStore.fetch(
+                record.key(), timeFrom, timeTo)) {

Review Comment:
   For my use case we always drop the right side of the join, so sacrificing neither would be nice. Would adding a config for this over complicate things? 



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