equip.data
Class FileBackedMemoryDataStore

java.lang.Object
  equip.data.MemoryDataStore
      equip.data.FileBackedMemoryDataStore

All Implemented Interfaces:

IDataStore

public class FileBackedMemoryDataStore

extends MemoryDataStore

Like MemoryDataStore, but attempts to persist dataspace contents through use of checkpoint and event log files.

See notes for DataDelegate for configuring a dataspace to make use of a custom data store such as this. Note that you should probably also fix the responsible ID for the DataDelegate.

Configuration:

 STOREID.path: DIRECTORYPATH [default "." - will use/create STOREID subdirectory]
 STOREID.checkpointEventCount: EVENTS-BETWEEN-CHECKPOINTS [default 1000]
 STOREID.maxFlushIntervalS: MAX-TIME-BETWEE-EVENTS-FLUSH [default 10, 0 to flush every event]
 STOREID.writeProcessBound: T/F [default T]
 STOREID.writePureEvents: T/F [default T]
 STOREID.restoreProcessBound: T/F [default F - don't enable this unless you are really sure :-)]
 

Files/formats. All files are in the STOREID subdirectory of the STOREID.path.

• checkpoint-UNIXTIME.eqbser - a binary serialisation of the datastore checkpoint from time UNIXTIME comprising a String ("equip-checkpoint"), an int32 file/serialisation version number (currently 2), an equip.data.GUID event log unique id for this checkpoint file [new for v2], an equip.data.GUID event log unique id for the event file which this immediately follows (else null or nullid) [new for v2], an equip.data.GUID responsble id, an equip.runtime.Time of the start time, an int32 item count, and that number of ItemBinding subclasses.
• events-UNIXTIME.eqbser - a binary serialisation of events starting from UNIXTIME comprising a String ("equip-events"), an int32 file/serialisation version number (currently 2), an equip.data.GUID event log unique id for this event file [new for v2], an equip.data.GUID event log unique id for the checkpoint file which this follows (else null or nullid) [new for v2], an equip.data.GUID responsble id, an equip.runtime.Time of the start time, and an EOF-terminated sequence of equip.runtime.Time of the event, an int32 of the size in bytes of the previous record (if known, including time, size, etc, else 0), an int32 of the size in bytes of the current record (if known, including time, size, etc, else 0), and the serialisation equip.data.Event subclass.

Nested Class Summary

Nested classes inherited from class equip.data.MemoryDataStore

MemoryDataStore.LeasedItem

Field Summary

static java.lang.String	CHECKPOINT_HEADER
static java.lang.String	CHECKPOINT_PREFIX
static java.lang.String	CHECKPOINT_SUFFIX
static int	CHECKPOINT_VERSION
static java.lang.String	EVENTS_HEADER
static java.lang.String	EVENTS_PREFIX
static java.lang.String	EVENTS_SUFFIX
static int	EVENTS_VERSION
static int	MIN_CHECKPOINT_VERSION
static int	MIN_EVENTS_VERSION
static java.lang.String	TEMP_SUFFIX

Fields inherited from class equip.data.MemoryDataStore

idMap, leasedItems, parentMultimap

Constructor Summary

FileBackedMemoryDataStore(java.lang.String storeId, GUID responsible)

Method Summary

void	flush() Flush any pending persistent records
boolean	handleAdd(AddEvent add) request that store handle the Add event, adding to itself accordingly.
boolean	handleDelete(DeleteEvent del) request that store handles the given delete, which it must iff it is currently maintaining state for the corresponding data item.
boolean	handleUpdate(UpdateEvent upd) request that store handles the given update, which it must iff it is currently maintaining state for it.
void	terminate() terminate - tidy up.

Methods inherited from class equip.data.MemoryDataStore

checkAdd, getCandidateItemBindings, getExpiredGUIDs, getFirstExpireTime, getItemBinding, getRemoveResponsibleGUIDs, holdsGUID, removeParent, truncateExpireTimes

Methods inherited from class java.lang.Object

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

Field Detail

CHECKPOINT_PREFIX

public static final java.lang.String CHECKPOINT_PREFIX

See Also:

Constant Field Values

CHECKPOINT_SUFFIX

public static final java.lang.String CHECKPOINT_SUFFIX

See Also:

Constant Field Values

TEMP_SUFFIX

public static final java.lang.String TEMP_SUFFIX

See Also:

Constant Field Values

EVENTS_PREFIX

public static final java.lang.String EVENTS_PREFIX

See Also:

Constant Field Values

EVENTS_SUFFIX

public static final java.lang.String EVENTS_SUFFIX

See Also:

Constant Field Values

CHECKPOINT_HEADER

public static final java.lang.String CHECKPOINT_HEADER

See Also:

Constant Field Values

CHECKPOINT_VERSION

public static final int CHECKPOINT_VERSION

See Also:

Constant Field Values

MIN_CHECKPOINT_VERSION

public static final int MIN_CHECKPOINT_VERSION

See Also:

Constant Field Values

EVENTS_HEADER

public static final java.lang.String EVENTS_HEADER

See Also:

Constant Field Values

EVENTS_VERSION

public static final int EVENTS_VERSION

See Also:

Constant Field Values

MIN_EVENTS_VERSION

public static final int MIN_EVENTS_VERSION

See Also:

Constant Field Values

Constructor Detail

FileBackedMemoryDataStore

public FileBackedMemoryDataStore(java.lang.String storeId,
                                 GUID responsible)
                          throws DataStoreConfigurationException

Method Detail

handleAdd

public boolean handleAdd(AddEvent add)

request that store handle the Add event, adding to itself accordingly. Note: also has to handle lease updates.

Specified by:

handleAdd in interface IDataStore

Overrides:

handleAdd in class MemoryDataStore

Parameters:

add - The AddEvent to be handled.

Returns:

true iff this store has handled the add event; false if declined. (normally as indicated by a call to IDataStore.checkAdd

handleUpdate

public boolean handleUpdate(UpdateEvent upd)

request that store handles the given update, which it must iff it is currently maintaining state for it. Note: implies currently no migration of item state between store(s).

Specified by:

handleUpdate in interface IDataStore

Overrides:

handleUpdate in class MemoryDataStore

Parameters:

upd - the UpdateEvent to be handled.

Returns:

true iff the update has been handled (and necessarily the item's state is maintained by this store).

handleDelete

public boolean handleDelete(DeleteEvent del)

request that store handles the given delete, which it must iff it is currently maintaining state for the corresponding data item.

Specified by:

handleDelete in interface IDataStore

Overrides:

handleDelete in class MemoryDataStore

Returns:

true iff the delete has been handled (and necessarily the item's state was maintained by this store).

terminate

public void terminate()

terminate - tidy up.

Specified by:

terminate in interface IDataStore

Overrides:

terminate in class MemoryDataStore

flush

public void flush()

Flush any pending persistent records

Specified by:

flush in interface IDataStore

Overrides:

flush in class MemoryDataStore