OffsetManager (venice API)

All Known Subinterfaces:

StorageMetadataService

All Known Implementing Classes:

DeepCopyOffsetManager, DeepCopyStorageMetadataService, InMemoryOffsetManager, InMemoryStorageMetadataService, MainIngestionStorageMetadataService, StorageEngineMetadataService
```
public interface OffsetManager
```
This class records the offset for every pair(topic,partition) this node is responsible for. It provides APIs that can query the last consumed offset for a specific (topic,partition) pair. This class should not checkpoint/flush to disk the offset for every request. Rather this should be an in memory operation and should be flushed to disk in a certain interval like 5 seconds or so by a background process like bdb checkpointer thread. TODO: offset manager should also be designed in case when there is a rebalance and the partition assignments to nodes in the cluster are changed.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`clearOffset(java.lang.String topicName, int partitionId)`
`OffsetRecord`	`getLastOffset(java.lang.String topicName, int partitionId)`	Gets the Last Known persisted offset of this consumer.
`void`	`put(java.lang.String topicName, int partitionId, OffsetRecord record)`	Records the offset with underlying/external storage.

- Method Detail
  - put
```
void put(java.lang.String topicName,
         int partitionId,
         OffsetRecord record)
  throws VeniceException
```
    Records the offset with underlying/external storage. Persistence to disk happens in configurable time interval by a background thread. For example in case of BDB the check pointer thread can be configured to do this.
    
    Parameters:
    
    topicName - kafka topic to which the consumer thread is registered to.
    
    partitionId - kafka partition id for which the consumer thread is registered to.
    
    record - OffSetRecord containing last read offset for the topic and partition combination.
    
    Throws:
    
    VeniceException
  - clearOffset
```
void clearOffset(java.lang.String topicName,
                 int partitionId)
```
  - getLastOffset
```
OffsetRecord getLastOffset(java.lang.String topicName,
                           int partitionId)
                    throws VeniceException
```
    Gets the Last Known persisted offset of this consumer.
    
    Parameters:
    
    topicName - kafka topic to which the consumer thread is registered to.
    
    partitionId - kafka partition id for which the consumer thread is registered to.
    
    Returns:
    
    OffsetRecord - contains offset and time when it was recorded before the consumer thread went down. consumer
    
    Throws:
    
    VeniceException