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package com.redis.spring.batch.reader;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader;
import com.redis.spring.batch.util.ConnectionUtils;
import io.lettuce.core.AbstractRedisClient;
import io.lettuce.core.Consumer;
import io.lettuce.core.ReadFrom;
import io.lettuce.core.RedisBusyException;
import io.lettuce.core.StreamMessage;
import io.lettuce.core.XGroupCreateArgs;
import io.lettuce.core.XReadArgs;
import io.lettuce.core.XReadArgs.StreamOffset;
import io.lettuce.core.api.StatefulConnection;
import io.lettuce.core.api.sync.RedisStreamCommands;
import io.lettuce.core.codec.RedisCodec;
public class StreamItemReader extends AbstractItemCountingItemStreamItemReader>
implements PollableItemReader> {
public enum AckPolicy {
AUTO, MANUAL
}
public static final Duration DEFAULT_POLL_DURATION = Duration.ofSeconds(1);
public static final String DEFAULT_OFFSET = "0-0";
public static final Duration DEFAULT_BLOCK = Duration.ofMillis(100);
public static final long DEFAULT_COUNT = 50;
public static final AckPolicy DEFAULT_ACK_POLICY = AckPolicy.AUTO;
private final AbstractRedisClient client;
private final RedisCodec codec;
private final K stream;
private final Consumer consumer;
private String offset = DEFAULT_OFFSET;
private Duration block = DEFAULT_BLOCK;
private long count = DEFAULT_COUNT;
private AckPolicy ackPolicy = DEFAULT_ACK_POLICY;
private StatefulConnection connection;
private Iterator> iterator = Collections.emptyIterator();
private MessageReader messageReader;
private String lastId;
private RedisStreamCommands commands;
private ReadFrom readFrom;
public StreamItemReader(AbstractRedisClient client, RedisCodec codec, K stream, Consumer consumer) {
this.client = client;
this.codec = codec;
this.stream = stream;
this.consumer = consumer;
}
private XReadArgs args(long blockMillis) {
return XReadArgs.Builder.count(count).block(blockMillis);
}
@Override
protected synchronized void doOpen() throws Exception {
if (messageReader == null) {
connection = ConnectionUtils.supplier(client, codec, readFrom).get();
commands = ConnectionUtils.sync(connection);
StreamOffset streamOffset = StreamOffset.from(stream, offset);
XGroupCreateArgs args = XGroupCreateArgs.Builder.mkstream(true);
try {
commands.xgroupCreate(streamOffset, consumer.getGroup(), args);
} catch (RedisBusyException e) {
// Consumer Group name already exists, ignore
}
lastId = offset;
messageReader = reader();
}
}
@Override
protected synchronized void doClose() throws Exception {
messageReader = null;
lastId = null;
if (connection != null) {
connection.close();
connection = null;
}
commands = null;
}
private MessageReader reader() {
if (ackPolicy == AckPolicy.MANUAL) {
return new ExplicitAckPendingMessageReader();
}
return new AutoAckPendingMessageReader();
}
@Override
protected StreamMessage doRead() throws Exception {
return poll(DEFAULT_POLL_DURATION.toMillis(), TimeUnit.MILLISECONDS);
}
@Override
public synchronized StreamMessage poll(long timeout, TimeUnit unit) {
if (!iterator.hasNext()) {
List> messages = messageReader.read(unit.toMillis(timeout));
if (messages == null || messages.isEmpty()) {
return null;
}
iterator = messages.iterator();
}
return iterator.next();
}
public List> readMessages() {
return messageReader.read(block.toMillis());
}
/**
* Acks given messages
*
* @param messages to be acked
*/
public Long ack(Iterable> messages) {
if (messages == null) {
return 0L;
}
Stream ids = StreamSupport.stream(messages.spliterator(), false).map(StreamMessage::getId);
return doAck(ids.toArray(String[]::new));
}
/**
* Acks given message ids
*
* @param ids message ids to be acked
* @return
*/
public Long ack(String... ids) {
if (ids.length == 0) {
return 0L;
}
lastId = ids[ids.length - 1];
return doAck(ids);
}
private Long doAck(String... ids) {
if (ids.length == 0) {
return 0L;
}
return commands.xack(stream, consumer.getGroup(), ids);
}
public static class StreamId implements Comparable {
public static final StreamId ZERO = StreamId.of(0, 0);
private final long millis;
private final long sequence;
public StreamId(long millis, long sequence) {
this.millis = millis;
this.sequence = sequence;
}
private static void checkPositive(String id, long number) {
if (number < 0) {
throw new IllegalArgumentException(String.format("not an id: %s", id));
}
}
public static StreamId parse(String id) {
int off = id.indexOf("-");
if (off == -1) {
long millis = Long.parseLong(id);
checkPositive(id, millis);
return StreamId.of(millis, 0L);
}
long millis = Long.parseLong(id.substring(0, off));
checkPositive(id, millis);
long sequence = Long.parseLong(id.substring(off + 1));
checkPositive(id, sequence);
return StreamId.of(millis, sequence);
}
public static StreamId of(long millis, long sequence) {
return new StreamId(millis, sequence);
}
public String toStreamId() {
return millis + "-" + sequence;
}
@Override
public String toString() {
return toStreamId();
}
@Override
public int compareTo(StreamId o) {
long diff = millis - o.millis;
if (diff != 0) {
return Long.signum(diff);
}
return Long.signum(sequence - o.sequence);
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof StreamId)) {
return false;
}
StreamId o = (StreamId) obj;
return o.millis == millis && o.sequence == sequence;
}
@Override
public int hashCode() {
long val = millis * 31 * sequence;
return (int) (val ^ (val >> 32));
}
}
private interface MessageReader {
/**
* Reads messages from a stream
*
* @param commands Synchronous executed commands for Streams
* @param args Stream read command args
* @return list of messages retrieved from the stream or empty list if no
* messages available
* @throws MessageReadException
*/
List> read(long blockMillis);
}
private class ExplicitAckPendingMessageReader implements MessageReader {
@SuppressWarnings("unchecked")
protected List> readMessages(XReadArgs args) {
return recover(commands.xreadgroup(consumer, args, StreamOffset.from(stream, DEFAULT_OFFSET)));
}
protected List> recover(List> messages) {
if (messages.isEmpty()) {
return messages;
}
List> recoveredMessages = new ArrayList<>();
List> messagesToAck = new ArrayList<>();
StreamId recoveryId = StreamId.parse(lastId);
for (StreamMessage message : messages) {
StreamId messageId = StreamId.parse(message.getId());
if (messageId.compareTo(recoveryId) > 0) {
recoveredMessages.add(message);
lastId = message.getId();
} else {
messagesToAck.add(message);
}
}
ack(messagesToAck);
return recoveredMessages;
}
protected MessageReader messageReader() {
return new ExplicitAckMessageReader();
}
@Override
public List> read(long blockMillis) {
List> messages;
messages = readMessages(args(blockMillis));
if (messages.isEmpty()) {
messageReader = messageReader();
return messageReader.read(blockMillis);
}
return messages;
}
}
private class ExplicitAckMessageReader implements MessageReader {
@SuppressWarnings("unchecked")
@Override
public List> read(long blockMillis) {
return commands.xreadgroup(consumer, args(blockMillis), StreamOffset.lastConsumed(stream));
}
}
private class AutoAckPendingMessageReader extends ExplicitAckPendingMessageReader {
@Override
protected StreamItemReader.MessageReader messageReader() {
return new AutoAckMessageReader();
}
@Override
protected List> recover(List> messages) {
ack(messages);
return Collections.emptyList();
}
}
private class AutoAckMessageReader extends ExplicitAckMessageReader {
@Override
public List> read(long blockMillis) {
List> messages = super.read(blockMillis);
ack(messages);
return messages;
}
}
public long streamLength() {
return commands.xlen(stream);
}
public ReadFrom getReadFrom() {
return readFrom;
}
public void setReadFrom(ReadFrom readFrom) {
this.readFrom = readFrom;
}
public String getOffset() {
return offset;
}
public void setOffset(String offset) {
this.offset = offset;
}
public Duration getBlock() {
return block;
}
public void setBlock(Duration block) {
this.block = block;
}
public long getCount() {
return count;
}
public void setCount(long count) {
this.count = count;
}
public AckPolicy getAckPolicy() {
return ackPolicy;
}
public void setAckPolicy(AckPolicy policy) {
this.ackPolicy = policy;
}
}
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