Package io.pravega.client.state.impl

Class StateSynchronizerImpl<StateT extends Revisioned>

java.lang.Object

io.pravega.client.state.impl.StateSynchronizerImpl<StateT>

All Implemented Interfaces:

StateSynchronizer<StateT>, java.lang.AutoCloseable

public class StateSynchronizerImpl<StateT extends Revisioned>
extends java.lang.Object
implements StateSynchronizer<StateT>

Nested Class Summary

Nested classes/interfaces inherited from interface io.pravega.client.state.StateSynchronizer

StateSynchronizer.UpdateGenerator<StateT extends Revisioned>, StateSynchronizer.UpdateGeneratorFunction<StateT extends Revisioned,ReturnT>

Constructor Summary

Constructors

Constructor	Description
StateSynchronizerImpl(Segment segment, RevisionedStreamClient<io.pravega.client.state.impl.UpdateOrInit<StateT>> client)	Creates a new instance of StateSynchronizer class.

Method Summary

Modifier and Type	Method	Description
long	bytesWrittenSinceCompaction()	Calculates the number of bytes that have been written since the state has last been compacted by calling StateSynchronizer.compact(Function) This may be useful when calculating when a compaction should occur.
void	close()	Closes the StateSynchronizer and frees any resources associated with it.
void	compact(java.util.function.Function<StateT,InitialUpdate<StateT>> compactor)	Provide a function that generates compacted version of localState so that we can drop some of the history updates.
void	fetchUpdates()	Fetch and apply all updates needed to the state object held locally up to date.
StateT	getState()	Gets the state object currently held in memory.
void	initialize(InitialUpdate<StateT> initial)	This method can be used to provide an initial value for a new stream if the stream has not been previously initialized.
java.lang.String	toString()
void	updateState(StateSynchronizer.UpdateGenerator<StateT> updateGenerator)	Creates a new update for the latest state object and applies it atomically.
<ReturnT> ReturnT	updateState(StateSynchronizer.UpdateGeneratorFunction<StateT,ReturnT> updateGenerator)	Similar to StateSynchronizer.updateState(UpdateGenerator) but this version returns a result object supplied by the StateSynchronizer.UpdateGeneratorFunction.
void	updateStateUnconditionally(Update<StateT> update)	Persists the provided update.
void	updateStateUnconditionally(java.util.List<? extends Update<StateT>> update)	Same as StateSynchronizer.updateStateUnconditionally(Update), except it persists multiple updates at the same time so they will not be interleaved with other updates.

Methods inherited from class java.lang.Object

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

Constructor Detail

StateSynchronizerImpl

public StateSynchronizerImpl(Segment segment,
                             RevisionedStreamClient<io.pravega.client.state.impl.UpdateOrInit<StateT>> client)

Creates a new instance of StateSynchronizer class.

Parameters:

segment - The segment.

client - The revisioned stream client this state synchronizer builds upon."

Method Detail

getState

public StateT getState()

Description copied from interface: StateSynchronizer

Gets the state object currently held in memory. This is a non-blocking call.

Specified by:

getState in interface StateSynchronizer<StateT extends Revisioned>

Returns:

Revisioned state object

fetchUpdates

public void fetchUpdates()

Description copied from interface: StateSynchronizer

Fetch and apply all updates needed to the state object held locally up to date.

Specified by:

fetchUpdates in interface StateSynchronizer<StateT extends Revisioned>

updateState

public void updateState(StateSynchronizer.UpdateGenerator<StateT> updateGenerator)

Description copied from interface: StateSynchronizer

Creates a new update for the latest state object and applies it atomically. The UpdateGenerator provided will be passed the latest state object and a list which it can populate with any updates that need to be applied. These updates are recorded and applied conditionally on the state object that was passed to the function being up to date. If another process was applying an update in parallel, the state is updated and updateGenerator will be called again with the new state object so that it may generate new updates. (Which may be different from the one it previously generated) By re-creating the updates in this way, consistency is guaranteed. When this function returns the generated updates will have been applied to the local state.

Specified by:

updateState in interface StateSynchronizer<StateT extends Revisioned>

Parameters:

updateGenerator - A function that given the current state can supply updates that should be applied.

updateState

public <ReturnT> ReturnT updateState(StateSynchronizer.UpdateGeneratorFunction<StateT,ReturnT> updateGenerator)

Description copied from interface: StateSynchronizer

Similar to StateSynchronizer.updateState(UpdateGenerator) but this version returns a result object supplied by the StateSynchronizer.UpdateGeneratorFunction. This is useful if the calling code wishes to do something in response to the update. As an example suppose the update type was MyUpdate and each update and an associated key. Then it might be useful to return the updated keys:

 
 List<String> updated = stateSynchronizer.updateState((state, updates) -> {
      List<MyUpdate> toAdd = findUpdatesForState(state);
      updates.addAll(toAdd);
      return toAdd.stream().map(a -> a.getKey()).collect(Collectors.toList());
 });
 
 

Specified by:

updateState in interface StateSynchronizer<StateT extends Revisioned>

Type Parameters:

ReturnT - They type of the result returned by the updateGenerator

Parameters:

updateGenerator - A function which give the state can supply updates that should be applied.

Returns:

the result returned by the updateGenerator.

updateStateUnconditionally

public void updateStateUnconditionally(Update<StateT> update)

Description copied from interface: StateSynchronizer

Persists the provided update. To ensure consistent ordering of updates across hosts the update is not applied locally until StateSynchronizer.fetchUpdates() is called.

Specified by:

updateStateUnconditionally in interface StateSynchronizer<StateT extends Revisioned>

Parameters:

update - The update that all other processes should receive.

updateStateUnconditionally

public void updateStateUnconditionally(java.util.List<? extends Update<StateT>> update)

Description copied from interface: StateSynchronizer

Same as StateSynchronizer.updateStateUnconditionally(Update), except it persists multiple updates at the same time so they will not be interleaved with other updates.

Specified by:

updateStateUnconditionally in interface StateSynchronizer<StateT extends Revisioned>

Parameters:

update - The updates that all other processes should receive.

initialize

public void initialize(InitialUpdate<StateT> initial)

Description copied from interface: StateSynchronizer

This method can be used to provide an initial value for a new stream if the stream has not been previously initialized. If the stream was already initialized nothing will be changed, and the local state will be updated as though StateSynchronizer.fetchUpdates()

Specified by:

initialize in interface StateSynchronizer<StateT extends Revisioned>

Parameters:

initial - The initializer for the state

bytesWrittenSinceCompaction

public long bytesWrittenSinceCompaction()

Description copied from interface: StateSynchronizer

Calculates the number of bytes that have been written since the state has last been compacted by calling StateSynchronizer.compact(Function) This may be useful when calculating when a compaction should occur.

Specified by:

bytesWrittenSinceCompaction in interface StateSynchronizer<StateT extends Revisioned>

Returns:

The number of bytes written since the last call to StateSynchronizer.compact(Function)

compact

public void compact(java.util.function.Function<StateT,InitialUpdate<StateT>> compactor)

Description copied from interface: StateSynchronizer

Provide a function that generates compacted version of localState so that we can drop some of the history updates.

NOTE: If InitialUpdate returned does not generate local state exactly corruption will occur.

Specified by:

compact in interface StateSynchronizer<StateT extends Revisioned>

Parameters:

compactor - An generator of InitialUpdates given a state.

close

public void close()

Description copied from interface: StateSynchronizer

Closes the StateSynchronizer and frees any resources associated with it. (It may no longer be used)

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface StateSynchronizer<StateT extends Revisioned>

See Also:

AutoCloseable.close()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object