com.devexperts.qd.ng

Class RecordSource

java.lang.Object

com.devexperts.qd.ng.RecordSource

All Implemented Interfaces:

DataIterator, SubscriptionIterator

Direct Known Subclasses:

RecordBuffer

public abstract class RecordSource
extends Object
implements DataIterator, SubscriptionIterator

Read-only sequence of records that is available via RecordCursor using next() method. It supports navigation to arbitrary records by their position via getPosition, setPosition, abd cursorAt(long) methods and, thus, can be read multiple times. It can be sliced with newSource method.

This abstract class is replacing legacy interfaces DataIterator and SubscriptionIterator.

Field Summary

Fields

Modifier and Type	Field and Description
static RecordSource	VOID An empty record source.

Method Summary

Modifier and Type	Method and Description
abstract RecordCursor	current() Returns read cursor at the current position.
abstract RecordCursor	cursorAt(long position) Returns read cursor at a specified position.
abstract int	getCipher() Deprecated. Use next().
abstract long	getLimit() Returns limit of this source, which is the position of after the last record returned by next().
abstract RecordMode	getMode() Returns mode of this record source.
abstract long	getPosition() Returns position of the current record.
abstract String	getSymbol() Deprecated. Use next().
abstract long	getTime() Deprecated. Use next().
abstract RecordSource	newSource() Returns new RecordSource that reads this record source from its current position to its limit.
abstract RecordSource	newSource(long start, long end) Returns new RecordSource that reads this record source from the specified start position to the specified end position.
abstract RecordCursor	next() Returns read cursor at the current position and advances position to next record.
abstract int	nextIntField() Deprecated. Use next().
abstract Object	nextObjField() Deprecated. Use next().
abstract DataRecord	nextRecord() Deprecated. Use next().
abstract boolean	retrieve(RecordSink sink) Retrieves all records from position to limit into the given sink and advances position while the sink has capacity.
abstract void	setPosition(long position) Changes position of the current record.

Methods inherited from class java.lang.Object

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

Field Detail

VOID

public static final RecordSource VOID

An empty record source.

Method Detail

getMode

public abstract RecordMode getMode()

Returns mode of this record source. This is the RecordCursor mode for the results of next(), cursorAt(long), and current() methods.

Returns:

mode of this record source.

retrieve

public abstract boolean retrieve(RecordSink sink)

Retrieves all records from position to limit into the given sink and advances position while the sink has capacity.

Parameters:

sink - the sink.

Returns:

true if all data was retrieved, false if sink ran out of capacity and more records remain to retrieve.

next

public abstract RecordCursor next()

Returns read cursor at the current position and advances position to next record. The result of this method is null when position is equal to limit.

The mode of the resulting cursor is the same as returned by getMode().

Returns:

read cursor at the current position.

cursorAt

public abstract RecordCursor cursorAt(long position)

Returns read cursor at a specified position. This position should have been previously returned by getPosition() or getLimit() method. Invoking this method at the current position results in the same cursor as the call current() or call to next() without the side effect of advancing position. The result of this method at the current limit is null.

The mode of the resulting cursor is the same as returned by getMode().

Returns:

read cursor at the specified position.

Throws:

IndexOutOfBoundsException - if position is invalid or above current limit.

current

public abstract RecordCursor current()

Returns read cursor at the current position. Effect is same as cursorAt(getPosition()), but faster. It is the same as call to next() without the side effect of advancing position.

The mode of the resulting cursor is the same as returned by getMode().

Returns:

read cursor at the current position.

getPosition

public abstract long getPosition()

Returns position of the current record. This record will be read by next() method.

setPosition

public abstract void setPosition(long position)

Changes position of the current record. Only values that were previously returned by getPosition(), getLimit() or next().getPosition() methods are allowed here.

Parameters:

position - new position.

Throws:

IndexOutOfBoundsException - if position is invalid or above current limit.

getLimit

public abstract long getLimit()

Returns limit of this source, which is the position of after the last record returned by next().

newSource

public abstract RecordSource newSource()

Returns new RecordSource that reads this record source from its current position to its limit. It is equivalent to newSource(getPosition(), getLimit()).

See Also:

newSource(long, long)

newSource

public abstract RecordSource newSource(long start,
                                       long end)

Returns new RecordSource that reads this record source from the specified start position to the specified end position.

See Also:

newSource()

getCipher

public abstract int getCipher()

Deprecated. Use next().

Returns cipher for the current record returned by last call to DataIterator.nextRecord(). Returns 0 if not encoded or if no current record is being iterated.

Specified by:

getCipher in interface DataIterator

Specified by:

getCipher in interface SubscriptionIterator

getSymbol

public abstract String getSymbol()

Deprecated. Use next().

Returns symbol for the current record returned by last call to DataIterator.nextRecord(). Returns null if encoded or if no current record is being iterated.

Specified by:

getSymbol in interface DataIterator

Specified by:

getSymbol in interface SubscriptionIterator

nextRecord

public abstract DataRecord nextRecord()

Deprecated. Use next().

Returns next record. Returns null if no more records available.

Specified by:

nextRecord in interface DataIterator

Specified by:

nextRecord in interface SubscriptionIterator

nextIntField

public abstract int nextIntField()

Deprecated. Use next().

Returns next Int-field within current record being iterated.

Specified by:

nextIntField in interface DataIterator

nextObjField

public abstract Object nextObjField()

Deprecated. Use next().

Returns next Obj-field within current record being iterated.

Specified by:

nextObjField in interface DataIterator

getTime

public abstract long getTime()

Deprecated. Use next().

Returns time for the current record returned by last call to SubscriptionIterator.nextRecord(). Returns 0 if not historical or if no current record is being iterated.

Specified by:

getTime in interface SubscriptionIterator