com.crankuptheamps.client

Class HybridPublishStore

java.lang.Object

com.crankuptheamps.client.HybridPublishStore

All Implemented Interfaces:

Store, java.lang.AutoCloseable

public class HybridPublishStore
extends java.lang.Object
implements Store

PublishStore that stores first in memory, and swaps excess out to disk.

Nested Class Summary

Nested classes/interfaces inherited from interface com.crankuptheamps.client.Store

Store.StoreReplayer

Field Summary

Fields

Modifier and Type	Field and Description
protected int	_cap
protected PublishStore	_fileStore
protected int	_lowWatermark
protected MemoryPublishStore	_memoryStore
protected java.lang.String	_path

Fields inherited from interface com.crankuptheamps.client.Store

SOWDeleteByBookmark, SOWDeleteByBookmarkCancel, SOWDeleteByData, SOWDeleteByFilter, SOWDeleteByKeys

Constructor Summary

Constructors

Constructor and Description
HybridPublishStore(java.lang.String path, int cap) Constructor for the HybridPublishStore.

Method Summary

Modifier and Type	Method and Description
void	close() Closes both the memory store and the file store.
void	discardUpTo(long index) Discards data from both the disk store and memory store up to the specified index.
void	flush() Flushes the memory store and, if necessary, the file store.
void	flush(long timeout) Flushes the memory store and, if necessary, the file store with a specified timeout.
boolean	getErrorOnPublishGap() Get whether the Store will throw a PublishGapException from discardUpTo if the sequence number being discarded is less then the current last persisted.
long	getLastPersisted() Gets the last persisted sequence number from the file store.
long	getLowestUnpersisted() Returns the lowest sequence number currently in the store.
void	replay(Store.StoreReplayer replayer) Replays messages using the provided replayer, ensuring no swapping occurs during the replay process.
boolean	replaySingle(Store.StoreReplayer replayer, long index) Replays a single message using the provided replayer and index.
void	setErrorOnPublishGap(boolean errorOnGap) Set whether the Store should throw a PublishGapException from discardUpTo if the sequence number being discarded is less then the current last persisted.
void	setLowWatermark(int lowWatermark_) Sets the low watermark; once we start swapping out to disk, we keep going until the number of entries in memory is lower than this.
void	setMessage(Message m) Sets a message in both the memory store and the disk store.
void	setResizeHandler(PublishStoreResizeHandler handler) Sets a resize handler for both the file store and the memory store.
void	store(Message message) Stores a message in the hybrid store, swapping to disk if memory usage exceeds capacity.
long	unpersistedCount() Gets the count of unpersisted messages in both the disk store and memory store

Methods inherited from class java.lang.Object

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

Field Detail

_fileStore

protected PublishStore _fileStore

_memoryStore

protected MemoryPublishStore _memoryStore

_cap

protected int _cap

_path

protected java.lang.String _path

_lowWatermark

protected int _lowWatermark

Constructor Detail

HybridPublishStore

public HybridPublishStore(java.lang.String path,
                          int cap)
                   throws StoreException

Constructor for the HybridPublishStore.

Parameters:

path - The path for the disk-based storage.

cap - The maximum number of messages that can be stored in memory. It is an integer that defines how many messages the in-memory storage component of the HybridPublishStore can hold before swapping excess data out to disk.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

Method Detail

setLowWatermark

public void setLowWatermark(int lowWatermark_)

Sets the low watermark; once we start swapping out to disk, we keep going until the number of entries in memory is lower than this. This method allows changing the low watermark value while ensuring it doesn't exceed the maximum capacity.

Parameters:

lowWatermark_ - The number of entries to serve as a low watermark.

getLowestUnpersisted

public long getLowestUnpersisted()

Returns the lowest sequence number currently in the store.

Specified by:

getLowestUnpersisted in interface Store

Returns:

The lowest sequence number of an operation in the store.

discardUpTo

public void discardUpTo(long index)
                 throws StoreException

Discards data from both the disk store and memory store up to the specified index.

Specified by:

discardUpTo in interface Store

Parameters:

index - The index up to which data should be discarded.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

See Also:

Store.discardUpTo(long)

replay

public void replay(Store.StoreReplayer replayer)
            throws StoreException,
                   DisconnectedException

Replays messages using the provided replayer, ensuring no swapping occurs during the replay process.

Specified by:

replay in interface Store

Parameters:

replayer - The replayer used to replay messages.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

DisconnectedException - Thrown when the store is disconnected.

See Also:

Store.replay(com.crankuptheamps.client.Store.StoreReplayer)

replaySingle

public boolean replaySingle(Store.StoreReplayer replayer,
                            long index)
                     throws StoreException,
                            DisconnectedException

Replays a single message using the provided replayer and index.

Specified by:

replaySingle in interface Store

Parameters:

replayer - The replayer used to replay the message.

index - The index of the message to replay.

Returns:

true if the message was successfully replayed, false otherwise.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

DisconnectedException - Thrown when the store is disconnected.

See Also:

Store.replaySingle(com.crankuptheamps.client.Store.StoreReplayer, long)

unpersistedCount

public long unpersistedCount()

Gets the count of unpersisted messages in both the disk store and memory store

Specified by:

unpersistedCount in interface Store

Returns:

The total count of unpersisted messages.

See Also:

Store.unpersistedCount()

store

public void store(Message message)
           throws StoreException

Stores a message in the hybrid store, swapping to disk if memory usage exceeds capacity.

Specified by:

store in interface Store

Parameters:

message - The message to store.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

setMessage

public void setMessage(Message m)

Sets a message in both the memory store and the disk store.

Specified by:

setMessage in interface Store

Parameters:

m - The message to set.

getLastPersisted

public long getLastPersisted()
                      throws StoreException

Gets the last persisted sequence number from the file store. The file store value is always considered correct.

Specified by:

getLastPersisted in interface Store

Returns:

The last persisted sequence number.

Throws:

StoreException - Thrown when an operation fails with details of the failure.

flush

public void flush()
           throws TimedOutException

Flushes the memory store and, if necessary, the file store.

Specified by:

flush in interface Store

Throws:

TimedOutException - Thrown if the flush operation times out.

flush

public void flush(long timeout)
           throws TimedOutException

Flushes the memory store and, if necessary, the file store with a specified timeout.

Specified by:

flush in interface Store

Parameters:

timeout - The maximum time to wait for the flush operation to complete.

Throws:

TimedOutException - Thrown if the flush operation times out.

setResizeHandler

public void setResizeHandler(PublishStoreResizeHandler handler)

Sets a resize handler for both the file store and the memory store.

Specified by:

setResizeHandler in interface Store

Parameters:

handler - The resize handler to set.

close

public void close()
           throws java.lang.Exception

Closes both the memory store and the file store.

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.lang.Exception - Thrown if an error occurs during closure.

getErrorOnPublishGap

public boolean getErrorOnPublishGap()

Get whether the Store will throw a PublishGapException from discardUpTo if the sequence number being discarded is less then the current last persisted.

Specified by:

getErrorOnPublishGap in interface Store

Returns:

If true, an exception will be thrown during logon if a gap could be created. If false, logon is allowed to proceed.

setErrorOnPublishGap

public void setErrorOnPublishGap(boolean errorOnGap)

Set whether the Store should throw a PublishGapException from discardUpTo if the sequence number being discarded is less then the current last persisted. This can occur if the client fails over to a server that has not been synchronously replicated to by its previous server, which lead to the new server having a gap in messages from this client.

Specified by:

setErrorOnPublishGap in interface Store

Parameters:

errorOnGap - If true, an exception will be thrown during logon if a gap could be created. If false, allow the logon to proceed.