本文主要研究一下rocketmq的ConsumeFromWhere
rocketmq-common-4.5.2-sources.jar!/org/apache/rocketmq/common/consumer/ConsumeFromWhere.java
public enum ConsumeFromWhere {
CONSUME_FROM_LAST_OFFSET,
@Deprecated
CONSUME_FROM_LAST_OFFSET_AND_FROM_MIN_WHEN_BOOT_FIRST,
@Deprecated
CONSUME_FROM_MIN_OFFSET,
@Deprecated
CONSUME_FROM_MAX_OFFSET,
CONSUME_FROM_FIRST_OFFSET,
CONSUME_FROM_TIMESTAMP,
}
rocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/impl/consumer/RebalancePushImpl.java
public class RebalancePushImpl extends RebalanceImpl {
//......
@Override
public long computePullFromWhere(MessageQueue mq) {
long result = -1;
final ConsumeFromWhere consumeFromWhere = this.defaultMQPushConsumerImpl.getDefaultMQPushConsumer().getConsumeFromWhere();
final OffsetStore offsetStore = this.defaultMQPushConsumerImpl.getOffsetStore();
switch (consumeFromWhere) {
case CONSUME_FROM_LAST_OFFSET_AND_FROM_MIN_WHEN_BOOT_FIRST:
case CONSUME_FROM_MIN_OFFSET:
case CONSUME_FROM_MAX_OFFSET:
case CONSUME_FROM_LAST_OFFSET: {
long lastOffset = offsetStore.readOffset(mq, ReadOffsetType.READ_FROM_STORE);
if (lastOffset >= 0) {
result = lastOffset;
}
// First start,no offset
else if (-1 == lastOffset) {
if (mq.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
result = 0L;
} else {
try {
result = this.mQClientFactory.getMQAdminImpl().maxOffset(mq);
} catch (MQClientException e) {
result = -1;
}
}
} else {
result = -1;
}
break;
}
case CONSUME_FROM_FIRST_OFFSET: {
long lastOffset = offsetStore.readOffset(mq, ReadOffsetType.READ_FROM_STORE);
if (lastOffset >= 0) {
result = lastOffset;
} else if (-1 == lastOffset) {
result = 0L;
} else {
result = -1;
}
break;
}
case CONSUME_FROM_TIMESTAMP: {
long lastOffset = offsetStore.readOffset(mq, ReadOffsetType.READ_FROM_STORE);
if (lastOffset >= 0) {
result = lastOffset;
} else if (-1 == lastOffset) {
if (mq.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
try {
result = this.mQClientFactory.getMQAdminImpl().maxOffset(mq);
} catch (MQClientException e) {
result = -1;
}
} else {
try {
long timestamp = UtilAll.parseDate(this.defaultMQPushConsumerImpl.getDefaultMQPushConsumer().getConsumeTimestamp(),
UtilAll.YYYYMMDDHHMMSS).getTime();
result = this.mQClientFactory.getMQAdminImpl().searchOffset(mq, timestamp);
} catch (MQClientException e) {
result = -1;
}
}
} else {
result = -1;
}
break;
}
default:
break;
}
return result;
}
//......
}