Package io.camunda.zeebe.engine.state.migration

Class MemoryBoundedColumnIteration

java.lang.Object

io.camunda.zeebe.engine.state.migration.MemoryBoundedColumnIteration

public final class MemoryBoundedColumnIteration
extends Object

Constructor Summary

Constructors

Constructor	Description
MemoryBoundedColumnIteration()
MemoryBoundedColumnIteration(long memoryLimitBytes)

Method Summary

Modifier and Type	Method	Description
<KeyT extends DbKey, ValueT extends DbValue> void	drain(ColumnFamily<KeyT,ValueT> columnFamily, BiConsumer<KeyT,ValueT> consumer)	Drains iterates through all key value pairs of a column family and feeds them a consumer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

MemoryBoundedColumnIteration

public MemoryBoundedColumnIteration()

MemoryBoundedColumnIteration

public MemoryBoundedColumnIteration(long memoryLimitBytes)

Method Details

drain

public <KeyT extends DbKey,
ValueT extends DbValue>
void drain(ColumnFamily<KeyT,ValueT> columnFamily,
 BiConsumer<KeyT,ValueT> consumer)

Drains iterates through all key value pairs of a column family and feeds them a consumer. Once the consumer returns, it will remove the key from the column.

This iteration is done in chunks to minimize memory usage of the transaction. The usage is estimated based on the key and value length, which is only roughly accurate; do improve this in the future when there's a need (e.g. fanning out a key-value pair to multiple columns, for example).

Type Parameters:

KeyT - the type of the key

ValueT - the type of the value

Parameters:

columnFamily - the column family to drain

consumer - the consumer which handles the drained pairs