com.e4graph
Class Storage

java.lang.Object
  |
  +--com.e4graph.Storage

public final class Storage

extends java.lang.Object

Field Summary

static int	AUTOCOMMIT AUTOCOMMIT may be set in the state of a Storage, meaning that the storage is auto-committed from time to time by the e4Graph runtime system (off by default).
static int	AUTOGC AUTOGC may be set in the state of a Storage, meaning that the e4Graph runtime performs GCs on this storage as needed (on by default).
static int	BIGPREALLOC BIGPREALLOC may be set in the state of a Storage, meaning that big areas are pre-allocated to hold newly created nodes and vertices (off by default).
static int	COMMITATCLOSE COMMITATCLOSE may be set in the state of a Storage, meaning that the storage should be committed when closed (on by default).
static int	COMPACTATCLOSE COMPACTATCLOSE may be set in the state of a Storage, meaning that the storag is compacted to its smallest possible on-disk size when it is closed (off by default).
static int	DEFAULTSTATE DEFAULTSTATE denotes the default state of a Storage, consisting of COMMITATCLOSE, OPENGC and AUTOGC.
static int	GCBEFORECOMMIT GCBEFORECOMMIT may be set in the state of a Storage, meaning that a GC is performed on this storage before it is committed (off by default).
static int	INVALID This value represents the storageIndex of an invalid storage.
static java.lang.String	METAKIT This is the name of the default driver to use to manage the persistence of this storage.
static int	OPENGC OPENGC may be set in the state of a Storage, meaning that a GC should be performed (as necessary) when the storage is opened (on by default).

Constructor Summary

Storage()
Default constructor, constructs an invalid storage.

Storage(java.lang.String name, java.lang.String driver)
Constructor that uses the given name and driver to construct a storage.

Storage(java.lang.String name, java.lang.String driver, int configuration)
Constructor that in addition to a name and driver for the storage also accepts an initial configuration state.

Method Summary

void	close() Close the storage, potentially committing any unsaved changes.
boolean	commit() Commit any unsaved changes in this storage to persistent storage.
boolean	copyTo(com.e4graph.Storage otherStorage, boolean forceCommit) Copy the contents of this storage (including any uncommitted changes) to the other storage, and if forceCommit is true, force a commit action on the other storage after the copy.
boolean	delete() Delete the persistent form of this storage.
void	doGC() Do a garbage collection on this storage now.
java.lang.String	driver() Retrieve the String for the driver used to manage persistence for this storage.
boolean	equals(com.e4graph.Storage otherStorage) Two storages are equal if their storageIndex values are the same.
int	getGeneration() Retrieve the generation index for this storage.
int	getIndex() Retrieve the storageIndex for this storage.
com.e4graph.Node	getNode() Create a new detached node in this storage and return the Node object representing it.
com.e4graph.Node	getRoot() Retrieve a Node representing the currently designated root node of this storage.
int	getState() Retrieve the current storage state.
static com.e4graph.Storage	getStorage(int index, int generation) Retrieves a Storage object for a currently open storage, given its storageIndex.
int	getStorageIndex() Retrieve the storageIndex for this storage.
static com.e4graph.StorageIterator	getStorageIterator() Create an iterator that iterates over all storages that are accessible in Java.
com.e4graph.Vertex	getVertex(java.lang.String name, byte[] bytes) Create a new detached vertex with the given name and the binary value bytes, and return the Vertex object representing it.
com.e4graph.Vertex	getVertex(java.lang.String name, double d) Create a new detached vertex with the given name and the double value d, and return the Vertex object representing it.
com.e4graph.Vertex	getVertex(java.lang.String name, int i) Create a new detached vertex with the given name and integer value i, and return the Vertex object representing it.
com.e4graph.Vertex	getVertex(java.lang.String name, com.e4graph.Node n)
com.e4graph.Vertex	getVertex(java.lang.String name, java.lang.String s) Create a new detached vertex with the given name and the string value s, and return the Vertex object representing it.
boolean	isDirty() Are there uncommitted changes in this storage?
boolean	isValid() A storage is valid if the underlying e4Graph storage is valid and its storageIndex is not the constant INVALID.
void	markDirty() Mark this storage as having uncommitted changes that have not yet been saved to persistent storage.
java.lang.String	name() Retrieve the String name of this storage.
boolean	needsGC() Is a garbage collection needed for this storage (it is needed if there may be detached nodes and vertices which are not referenced by the user program).
boolean	setRoot(com.e4graph.Node newRoot) Set the currently designated root node of this storage to the e4Graph node denoted by the given newRoot.
int	setState(int statemask) Set the storage state to a new state, with changes taking effect immediately and affecting subsequent behavior.
static java.lang.String	version() Retrieves the version string for the e4Graph library in use.

Methods inherited from class java.lang.Object

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

Field Detail

COMMITATCLOSE

public static final int COMMITATCLOSE

COMMITATCLOSE may be set in the state of a Storage, meaning that the storage should be committed when closed (on by default).

See Also:

Constant Field Values

AUTOCOMMIT

public static final int AUTOCOMMIT

AUTOCOMMIT may be set in the state of a Storage, meaning that the storage is auto-committed from time to time by the e4Graph runtime system (off by default).

See Also:

Constant Field Values

OPENGC

public static final int OPENGC

OPENGC may be set in the state of a Storage, meaning that a GC should be performed (as necessary) when the storage is opened (on by default).

See Also:

Constant Field Values

GCBEFORECOMMIT

public static final int GCBEFORECOMMIT

GCBEFORECOMMIT may be set in the state of a Storage, meaning that a GC is performed on this storage before it is committed (off by default).

See Also:

Constant Field Values

AUTOGC

public static final int AUTOGC

AUTOGC may be set in the state of a Storage, meaning that the e4Graph runtime performs GCs on this storage as needed (on by default).

See Also:

Constant Field Values

BIGPREALLOC

public static final int BIGPREALLOC

BIGPREALLOC may be set in the state of a Storage, meaning that big areas are pre-allocated to hold newly created nodes and vertices (off by default).

See Also:

Constant Field Values

COMPACTATCLOSE

public static final int COMPACTATCLOSE

COMPACTATCLOSE may be set in the state of a Storage, meaning that the storag is compacted to its smallest possible on-disk size when it is closed (off by default).

See Also:

Constant Field Values

DEFAULTSTATE

public static final int DEFAULTSTATE

DEFAULTSTATE denotes the default state of a Storage, consisting of COMMITATCLOSE, OPENGC and AUTOGC.

See Also:

Constant Field Values

INVALID

public static final int INVALID

This value represents the storageIndex of an invalid storage.

See Also:

Constant Field Values

METAKIT

public static final java.lang.String METAKIT

This is the name of the default driver to use to manage the persistence of this storage.

See Also:

Constant Field Values

Constructor Detail

Storage

public Storage()

Default constructor, constructs an invalid storage.

Storage

public Storage(java.lang.String name,
               java.lang.String driver)

Constructor that uses the given name and driver to construct a storage.

Storage

public Storage(java.lang.String name,
               java.lang.String driver,
               int configuration)

Constructor that in addition to a name and driver for the storage also accepts an initial configuration state.

Method Detail

getStorageIterator

public static com.e4graph.StorageIterator getStorageIterator()

Create an iterator that iterates over all storages that are accessible in Java.

getStorage

public static com.e4graph.Storage getStorage(int index,
                                             int generation)
                                      throws StorageIsNotOpenException

Retrieves a Storage object for a currently open storage, given its storageIndex.

StorageIsNotOpenException

getIndex

public int getIndex()

Retrieve the storageIndex for this storage.

getStorageIndex

public int getStorageIndex()

Retrieve the storageIndex for this storage.

getGeneration

public int getGeneration()

Retrieve the generation index for this storage.

version

public static java.lang.String version()

Retrieves the version string for the e4Graph library in use.

isValid

public boolean isValid()

A storage is valid if the underlying e4Graph storage is valid and its storageIndex is not the constant INVALID.

equals

public boolean equals(com.e4graph.Storage otherStorage)

Two storages are equal if their storageIndex values are the same.

setState

public int setState(int statemask)

Set the storage state to a new state, with changes taking effect immediately and affecting subsequent behavior.

getState

public int getState()

Retrieve the current storage state.

commit

public boolean commit()

Commit any unsaved changes in this storage to persistent storage.

close

public void close()

Close the storage, potentially committing any unsaved changes.

copyTo

public boolean copyTo(com.e4graph.Storage otherStorage,
                      boolean forceCommit)

Copy the contents of this storage (including any uncommitted changes) to the other storage, and if forceCommit is true, force a commit action on the other storage after the copy.

delete

public boolean delete()

Delete the persistent form of this storage.

getRoot

public com.e4graph.Node getRoot()

Retrieve a Node representing the currently designated root node of this storage.

setRoot

public boolean setRoot(com.e4graph.Node newRoot)

Set the currently designated root node of this storage to the e4Graph node denoted by the given newRoot.

isDirty

public boolean isDirty()

Are there uncommitted changes in this storage?

markDirty

public void markDirty()

Mark this storage as having uncommitted changes that have not yet been saved to persistent storage.

name

public java.lang.String name()

Retrieve the String name of this storage.

driver

public java.lang.String driver()

Retrieve the String for the driver used to manage persistence for this storage.

getNode

public com.e4graph.Node getNode()

Create a new detached node in this storage and return the Node object representing it.

getVertex

public com.e4graph.Vertex getVertex(java.lang.String name,
                                    com.e4graph.Node n)

getVertex

public com.e4graph.Vertex getVertex(java.lang.String name,
                                    int i)

Create a new detached vertex with the given name and integer value i, and return the Vertex object representing it.

getVertex

public com.e4graph.Vertex getVertex(java.lang.String name,
                                    double d)

Create a new detached vertex with the given name and the double value d, and return the Vertex object representing it.

getVertex

public com.e4graph.Vertex getVertex(java.lang.String name,
                                    java.lang.String s)

Create a new detached vertex with the given name and the string value s, and return the Vertex object representing it.

getVertex

public com.e4graph.Vertex getVertex(java.lang.String name,
                                    byte[] bytes)

Create a new detached vertex with the given name and the binary value bytes, and return the Vertex object representing it.

doGC

public void doGC()

Do a garbage collection on this storage now.

needsGC

public boolean needsGC()

Is a garbage collection needed for this storage (it is needed if there may be detached nodes and vertices which are not referenced by the user program).