Package org.apache.kafka.streams.state.internals

Class InMemoryWindowStore

java.lang.Object

org.apache.kafka.streams.state.internals.InMemoryWindowStore

All Implemented Interfaces:

StateStore, ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>, WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

public class InMemoryWindowStore
extends Object
implements WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Method Summary

Modifier and Type	Method	Description
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	all()	Gets all the key-value pairs in the existing windows.
void	close()	Close the storage engine.
byte[]	fetch(org.apache.kafka.common.utils.Bytes key, long windowStartTimestamp)	Get the value of key from a window.
WindowStoreIterator<byte[]>	fetch(org.apache.kafka.common.utils.Bytes key, long timeFrom, long timeTo)	Deprecated.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	fetch(org.apache.kafka.common.utils.Bytes from, org.apache.kafka.common.utils.Bytes to, long timeFrom, long timeTo)	Deprecated.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	fetchAll(long timeFrom, long timeTo)	Deprecated.
void	flush()	Flush any cached data
void	init(ProcessorContext context, StateStore root)	Initializes this state store.
boolean	isOpen()	Is this store open for reading and writing
String	name()	The name of this store.
boolean	persistent()	Return if the storage is persistent or not.
void	put(org.apache.kafka.common.utils.Bytes key, byte[] value)	Deprecated.
void	put(org.apache.kafka.common.utils.Bytes key, byte[] value, long windowStartTimestamp)	Put a key-value pair into the window with given window start timestamp

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.kafka.streams.state.WindowStore

fetch, fetch, fetchAll

Method Detail

name

public String name()

Description copied from interface: StateStore

The name of this store.

Specified by:

name in interface StateStore

Returns:

the storage name

init

public void init(ProcessorContext context,
                 StateStore root)

Description copied from interface: StateStore

Initializes this state store.

The implementation of this function must register the root store in the context via the ProcessorContext.register(StateStore, StateRestoreCallback) function, where the first StateStore parameter should always be the passed-in root object, and the second parameter should be an object of user's implementation of the StateRestoreCallback interface used for restoring the state store from the changelog.

Note that if the state store engine itself supports bulk writes, users can implement another interface BatchingStateRestoreCallback which extends StateRestoreCallback to let users implement bulk-load restoration logic instead of restoring one record at a time.

Specified by:

init in interface StateStore

put

@Deprecated
public void put(org.apache.kafka.common.utils.Bytes key,
                byte[] value)

Deprecated.

Description copied from interface: WindowStore

Use the current record timestamp as the windowStartTimestamp and delegate to WindowStore.put(Object, Object, long).

It's highly recommended to use WindowStore.put(Object, Object, long) instead, as the record timestamp is unlikely to be the correct windowStartTimestamp in general.

Specified by:

put in interface WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - The key to associate the value to

value - The value to update, it can be null; if the serialized bytes are also null it is interpreted as delete

put

public void put(org.apache.kafka.common.utils.Bytes key,
                byte[] value,
                long windowStartTimestamp)

Description copied from interface: WindowStore

Put a key-value pair into the window with given window start timestamp

If serialized value bytes are null it is interpreted as delete. Note that deletes will be ignored in the case of an underlying store that retains duplicates.

Specified by:

put in interface WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - The key to associate the value to

value - The value; can be null

windowStartTimestamp - The timestamp of the beginning of the window to put the key/value into

fetch

public byte[] fetch(org.apache.kafka.common.utils.Bytes key,
                    long windowStartTimestamp)

Description copied from interface: ReadOnlyWindowStore

Get the value of key from a window.

Specified by:

fetch in interface ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - the key to fetch

windowStartTimestamp - start timestamp (inclusive) of the window

Returns:

The value or null if no value is found in the window

fetch

@Deprecated
public WindowStoreIterator<byte[]> fetch(org.apache.kafka.common.utils.Bytes key,
                                         long timeFrom,
                                         long timeTo)

Deprecated.

Description copied from interface: WindowStore

Get all the key-value pairs with the given key and the time range from all the existing windows.

This iterator must be closed after use.

The time range is inclusive and applies to the starting timestamp of the window. For example, if we have the following windows:

 +-------------------------------+
 |  key  | start time | end time |
 +-------+------------+----------+
 |   A   |     10     |    20    |
 +-------+------------+----------+
 |   A   |     15     |    25    |
 +-------+------------+----------+
 |   A   |     20     |    30    |
 +-------+------------+----------+
 |   A   |     25     |    35    |
 +--------------------------------
 

And we call store.fetch("A", 10, 20) then the results will contain the first three windows from the table above, i.e., all those where 10 <= start time <= 20.

For each key, the iterator guarantees ordering of windows, starting from the oldest/earliest available window to the newest/latest window.

Specified by:

fetch in interface ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Specified by:

fetch in interface WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - the key to fetch

timeFrom - time range start (inclusive)

timeTo - time range end (inclusive)

Returns:

an iterator over key-value pairs <timestamp, value>

fetch

@Deprecated
public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> fetch(org.apache.kafka.common.utils.Bytes from,
                                                                                          org.apache.kafka.common.utils.Bytes to,
                                                                                          long timeFrom,
                                                                                          long timeTo)

Deprecated.

Description copied from interface: WindowStore

Get all the key-value pairs in the given key range and time range from all the existing windows.

This iterator must be closed after use.

Specified by:

fetch in interface ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Specified by:

fetch in interface WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

from - the first key in the range

to - the last key in the range

timeFrom - time range start (inclusive)

timeTo - time range end (inclusive)

Returns:

an iterator over windowed key-value pairs <Windowed<K>, value>

fetchAll

@Deprecated
public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> fetchAll(long timeFrom,
                                                                                             long timeTo)

Deprecated.

Description copied from interface: WindowStore

Gets all the key-value pairs that belong to the windows within in the given time range.

Specified by:

fetchAll in interface ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Specified by:

fetchAll in interface WindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

timeFrom - the beginning of the time slot from which to search (inclusive)

timeTo - the end of the time slot from which to search (inclusive)

Returns:

an iterator over windowed key-value pairs <Windowed<K>, value>

all

public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> all()

Description copied from interface: ReadOnlyWindowStore

Gets all the key-value pairs in the existing windows.

Specified by:

all in interface ReadOnlyWindowStore<org.apache.kafka.common.utils.Bytes,byte[]>

Returns:

an iterator over windowed key-value pairs <Windowed<K>, value>

persistent

public boolean persistent()

Description copied from interface: StateStore

Return if the storage is persistent or not.

Specified by:

persistent in interface StateStore

Returns:

true if the storage is persistent—false otherwise

isOpen

public boolean isOpen()

Description copied from interface: StateStore

Is this store open for reading and writing

Specified by:

isOpen in interface StateStore

Returns:

true if the store is open

flush

public void flush()

Description copied from interface: StateStore

Flush any cached data

Specified by:

flush in interface StateStore

close

public void close()

Description copied from interface: StateStore

Close the storage engine. Note that this function needs to be idempotent since it may be called several times on the same state store.

Users only need to implement this function but should NEVER need to call this api explicitly as it will be called by the library automatically when necessary

Specified by:

close in interface StateStore