Created
June 18, 2018 16:02
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One-to-many grouped
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package com.dexels.kafka.streams.remotejoin.ranged; | |
import java.util.ArrayList; | |
import java.util.List; | |
import java.util.Optional; | |
import java.util.function.BiFunction; | |
import org.apache.kafka.streams.KeyValue; | |
import org.apache.kafka.streams.kstream.Predicate; | |
import org.apache.kafka.streams.processor.AbstractProcessor; | |
import org.apache.kafka.streams.processor.ProcessorContext; | |
import org.apache.kafka.streams.state.KeyValueIterator; | |
import org.apache.kafka.streams.state.KeyValueStore; | |
import org.slf4j.Logger; | |
import org.slf4j.LoggerFactory; | |
import com.dexels.kafka.streams.base.StreamOperators; | |
import com.dexels.kafka.streams.remotejoin.PreJoinProcessor; | |
import com.dexels.replication.api.ReplicationMessage; | |
import com.dexels.replication.api.ReplicationMessage.Operation; | |
public class OneToManyGroupedProcessor extends AbstractProcessor<String, ReplicationMessage> { | |
private final static Logger logger = LoggerFactory.getLogger(OneToManyGroupedProcessor.class); | |
private String storeName; | |
private String groupedStoreName; | |
private boolean optional; | |
private KeyValueStore<String, ReplicationMessage> groupedLookupStore; | |
private KeyValueStore<String, ReplicationMessage> lookupStore; | |
private BiFunction<ReplicationMessage, List<ReplicationMessage>, ReplicationMessage> joinFunction; | |
private Predicate<String, ReplicationMessage> filterPredicate; | |
public OneToManyGroupedProcessor(String storeName, String groupedStoreName, boolean optional, | |
Optional<Predicate<String, ReplicationMessage>> filterPredicate, | |
BiFunction<ReplicationMessage, List<ReplicationMessage>, ReplicationMessage> joinFunction) { | |
this.storeName = storeName; | |
this.groupedStoreName = groupedStoreName; | |
this.optional = optional; | |
this.joinFunction = joinFunction; | |
this.filterPredicate = filterPredicate.orElse((k, v) -> true); | |
} | |
@SuppressWarnings("unchecked") | |
@Override | |
public void init(ProcessorContext context) { | |
this.lookupStore = (KeyValueStore<String, ReplicationMessage>) context.getStateStore(storeName); | |
this.groupedLookupStore = (KeyValueStore<String, ReplicationMessage>) context.getStateStore(groupedStoreName); | |
super.init(context); | |
} | |
@Override | |
public void process(String key, ReplicationMessage msg) { | |
boolean reverse = false; | |
if (key.endsWith(PreJoinProcessor.REVERSE_IDENTIFIER)) { | |
reverse = true; | |
key = key.substring(0, key.length() - PreJoinProcessor.REVERSE_IDENTIFIER.length()); | |
} | |
if (reverse) { | |
reverseJoin(key, msg); | |
} else { | |
if (msg == null) { | |
logger.debug("O2M Emitting null message with key: {}", key); | |
context().forward(key, null); | |
return; | |
} | |
forwardJoin(key, msg); | |
} | |
} | |
private void forwardJoin(String key, ReplicationMessage msg) { | |
try { | |
if (!filterPredicate.test(key, msg)) { | |
// filter says no | |
forwardMessage(key, msg.withOperation(Operation.DELETE)); | |
return; | |
} | |
} catch (Throwable t) { | |
logger.error("Error on checking filter predicate: {}", t); | |
} | |
List<ReplicationMessage> msgs = new ArrayList<>(); | |
try (KeyValueIterator<String, ReplicationMessage> it = groupedLookupStore.range(key + "|", key + "}")) { | |
while (it.hasNext()) { | |
KeyValue<String, ReplicationMessage> keyValue = it.next(); | |
msgs.add(keyValue.value); | |
} | |
} | |
ReplicationMessage joined = msg; | |
if (msgs.size() > 0) { | |
joined = joinFunction.apply(msg, msgs); | |
} | |
if (optional || msgs.size() > 0) { | |
forwardMessage(key, joined); | |
} else { | |
// We are not optional, and have not joined with any messages. Forward a delete | |
forwardMessage(key, joined.withOperation(Operation.DELETE)); | |
} | |
} | |
private void reverseJoin(String key, ReplicationMessage msg) { | |
String actualKey = StreamOperators.ungroupKeyReverse(key); | |
ReplicationMessage one = lookupStore.get(actualKey); | |
if (one == null) { | |
// We are doing a reverse join, but the original message isn't there. | |
// Nothing to do for us here | |
return; | |
} | |
// OneToMany, thus we need to find all the other messages that | |
// we also have to join with us. Effectively the same as a | |
// forward join. | |
forwardJoin(actualKey, one); | |
} | |
private void forwardMessage(String key, ReplicationMessage innerMessage) { | |
context().forward(key, innerMessage); | |
// flush downstream stores with null: | |
if (innerMessage.operation() == Operation.DELETE) { | |
logger.debug("Delete forwarded, appending null forward with key: {}", key); | |
context().forward(key, null); | |
} | |
} |
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