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package de.otto.synapse.consumer;
import de.otto.synapse.message.Key;
import de.otto.synapse.message.Message;
import de.otto.synapse.state.StateRepository;
import javax.annotation.Nonnull;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.regex.Pattern;
/**
* A {@code MessageConsumer} that is updating a {@link StateRepository}.
*
* @param the type of the {@link Message} payload
* @param the type of the {@link StateRepository} entries
*/
public class StatefulMessageConsumer implements MessageConsumer {
private final Pattern keyPattern;
private final StateRepository stateRepository;
private final Class
payloadType;
private final Function, String> keyMapper;
private final BiFunction, ? super Message, S> payloadToStateMapper;
/**
* Creates a StatefulMessageConsumer.
*
*
* The message's {@link Key#partitionKey()} is used as the key for repository entries.
*
*
* @param keyPattern the of-pattern of {@link de.otto.synapse.message.Message#getKey() message keys} accepted by this consumer.
* @param payloadType the payload type of the messages accepted by this consumer
* @param stateRepository the StateRepository that is holding the State
* @param payloadToStateMapper the mapper function used to map message payload to state entities
*/
public StatefulMessageConsumer(final String keyPattern,
final Class payloadType,
final StateRepository stateRepository,
final Function, S> payloadToStateMapper) {
this(keyPattern, payloadType, stateRepository, payloadToStateMapper, (message) -> message.getKey().partitionKey());
}
/**
* Creates a StatefulMessageConsumer.
*
*
* The message's {@link Key#partitionKey()} is used as the key for repository entries.
*
*
* @param keyPattern the of-pattern of {@link de.otto.synapse.message.Message#getKey() message keys} accepted by this consumer.
* @param payloadType the payload type of the messages accepted by this consumer
* @param stateRepository the StateRepository that is holding the State
* @param payloadToStateMapper the mapper function used to map message payload to state entities
*/
public StatefulMessageConsumer(final String keyPattern,
final Class payloadType,
final StateRepository stateRepository,
final BiFunction, Message, S> payloadToStateMapper) {
this(keyPattern, payloadType, stateRepository, payloadToStateMapper, (message) -> message.getKey().partitionKey());
}
/**
* Creates a StatefulMessageConsumer.
*
* @param keyPattern the of-pattern of {@link de.otto.synapse.message.Message#getKey() message keys} accepted by this consumer.
* @param payloadType the payload type of the messages accepted by this consumer
* @param stateRepository the StateRepository that is holding the State
* @param payloadToStateMapper the mapper function used to map message payload to state entities
* @param keyMapper the mapper function used to map message keys to StateRepository keys.
*/
public StatefulMessageConsumer(final String keyPattern,
final Class
payloadType,
final StateRepository stateRepository,
final Function, S> payloadToStateMapper,
final Function,String> keyMapper) {
this.keyPattern = Pattern.compile(keyPattern);
this.payloadType = payloadType;
this.stateRepository = stateRepository;
this.payloadToStateMapper = (_previousValue, message) -> payloadToStateMapper.apply(message);
this.keyMapper = keyMapper;
}
/**
* Creates a StatefulMessageConsumer.
*
* @param keyPattern the of-pattern of {@link de.otto.synapse.message.Message#getKey() message keys} accepted by this consumer.
* @param payloadType the payload type of the messages accepted by this consumer
* @param stateRepository the StateRepository that is holding the State
* @param payloadToStateMapper the mapper function used to map previous state entity and message payload to state entities
* @param keyMapper the mapper function used to map message keys to StateRepository keys.
*/
public StatefulMessageConsumer(final String keyPattern,
final Class
payloadType,
final StateRepository stateRepository,
final BiFunction, ? super Message, S> payloadToStateMapper,
final Function,String> keyMapper) {
this.keyPattern = Pattern.compile(keyPattern);
this.payloadType = payloadType;
this.stateRepository = stateRepository;
this.payloadToStateMapper = payloadToStateMapper;
this.keyMapper = keyMapper;
}
/**
* Returns the expected payload type of {@link Message events} consumed by this EventConsumer.
*
* @return payload type
*/
@Nonnull
@Override
public Class
payloadType() {
return payloadType;
}
/**
* Returns the pattern of {@link de.otto.synapse.message.Message#getKey() message keys} accepted by this consumer.
*
* @return Pattern
*/
@Nonnull
@Override
public Pattern keyPattern() {
return keyPattern;
}
@Override
public void accept(final Message
message) {
if (message.getPayload() == null) {
stateRepository.remove(keyMapper.apply(message));
} else {
stateRepository.compute(
keyMapper.apply(message),
(_key, previousValue) -> payloadToStateMapper.apply(previousValue, message));
}
}
}