com.graphhopper.storage

Interface DataAccess

All Superinterfaces:

AutoCloseable, Closeable, Storable<DataAccess>

All Known Implementing Classes:

AbstractDataAccess, MMapDataAccess, RAMDataAccess, UnsafeDataAccess

public interface DataAccess
extends Storable<DataAccess>

Abstraction of the underlying data structure with a unique id and location. To ensure that the id is unique use a Directory.attach or findAttach, if you don't need uniqueness call Directory.create. Current implementations are RAM and memory mapped access.

Life cycle: (1) object creation, (2) configuration (e.g. segment size), (3) create or loadExisting, (4) usage and calling ensureCapacity if necessary, (5) close

Author:

Peter Karich

Method Summary

Modifier and Type	Method and Description
DataAccess	copyTo(DataAccess da) Copies the content from this object into the specified one.
DataAccess	create(long bytes) The first time you use a DataAccess object after configuring it you need to call this method.
boolean	ensureCapacity(long bytes) Ensures that the capacity of this object is at least the specified bytes.
void	getBytes(long bytePos, byte[] values, int length) Get bytes from position 'index'
int	getHeader(int bytePos) Get 4 bytes from the header at 'index'
int	getInt(long bytePos) Get 4 bytes from position 'bytePos'
String	getName() The logical identification of this object.
int	getSegments()
int	getSegmentSize()
short	getShort(long bytePos) Get 2 bytes from position 'index'
DAType	getType()
void	rename(String newName) Renames the underlying DataAccess object.
void	setBytes(long bytePos, byte[] values, int length) Set bytes from position 'index' to the specified values
void	setHeader(int bytePos, int value) Set 4 bytes at the header space index to the specified value
void	setInt(long bytePos, int value) Set 4 bytes at position 'bytePos' to the specified value
DataAccess	setSegmentSize(int bytes) In order to increase allocated space one needs to layout the underlying storage in segments.
void	setShort(long bytePos, short value) Set 2 bytes at position 'index' to the specified value
void	trimTo(long bytes) Reduces the allocate space to the specified bytes.

Methods inherited from interface com.graphhopper.storage.Storable

close, flush, getCapacity, isClosed, loadExisting

Method Detail

getName

String getName()

The logical identification of this object.

rename

void rename(String newName)

Renames the underlying DataAccess object. (Flushing shouldn't be necessary before or afterwards)

Throws:

IllegalStateException - if a rename is not possible

setInt

void setInt(long bytePos,
            int value)

Set 4 bytes at position 'bytePos' to the specified value

getInt

int getInt(long bytePos)

Get 4 bytes from position 'bytePos'

setShort

void setShort(long bytePos,
              short value)

Set 2 bytes at position 'index' to the specified value

getShort

short getShort(long bytePos)

Get 2 bytes from position 'index'

setBytes

void setBytes(long bytePos,
              byte[] values,
              int length)

Set bytes from position 'index' to the specified values

getBytes

void getBytes(long bytePos,
              byte[] values,
              int length)

Get bytes from position 'index'

Parameters:

values - acts as output

setHeader

void setHeader(int bytePos,
               int value)

Set 4 bytes at the header space index to the specified value

getHeader

int getHeader(int bytePos)

Get 4 bytes from the header at 'index'

create

DataAccess create(long bytes)

The first time you use a DataAccess object after configuring it you need to call this method. After that first call you have to use ensureCapacity to ensure that enough space is reserved.

Specified by:

create in interface Storable<DataAccess>

ensureCapacity

boolean ensureCapacity(long bytes)

Ensures that the capacity of this object is at least the specified bytes. The first time you have to call 'create' instead.

Returns:

true if size was increased

See Also:

create(long)

trimTo

void trimTo(long bytes)

Reduces the allocate space to the specified bytes. Warning: it'll free the space even if it is in use!

copyTo

DataAccess copyTo(DataAccess da)

Copies the content from this object into the specified one.

getSegmentSize

int getSegmentSize()

Returns:

the size of one segment in bytes

setSegmentSize

DataAccess setSegmentSize(int bytes)

In order to increase allocated space one needs to layout the underlying storage in segments. This is how you can customize the size.

getSegments

int getSegments()

Returns:

the number of segments.

getType

DAType getType()

Returns:

the data access type of this object.