net.openhft.chronicle.queue

Interface ExcerptTailer

All Superinterfaces:

ExcerptCommon

All Known Subinterfaces:

Excerpt

All Known Implementing Classes:

SingleChronicleQueueExcerpts.StoreTailer

public interface ExcerptTailer
extends ExcerptCommon

The component that facilitates sequentially reading data from a ChronicleQueue.

Author:

peter.lawrey

Method Summary

Modifier and Type	Method and Description
ExcerptTailer	afterLastWritten(ChronicleQueue queue) Wind this tailer to after the last entry which wrote an entry to the queue
int	cycle()
TailerDirection	direction()
ExcerptTailer	direction(TailerDirection direction) Set the direction of movement.
long	index()
default MethodReader	methodReader(Object... objects) Reads messages from this tails as methods.
boolean	moveToIndex(long index) Randomly select an Excerpt.
boolean	readBytes(net.openhft.chronicle.bytes.Bytes using)
boolean	readBytes(net.openhft.chronicle.bytes.ReadBytesMarshallable marshallable)
boolean	readDocument(net.openhft.chronicle.wire.ReadMarshallable reader)
default net.openhft.chronicle.wire.DocumentContext	readingDocument() equivalent to readDocument(ReadMarshallable) but with out the use of a lambda expression.
net.openhft.chronicle.wire.DocumentContext	readingDocument(boolean includeMetaData)
default Map<String,Object>	readMap() Read a Map>String, Object> from the content.
String	readText() Read the next message as a String
boolean	readText(StringBuilder sb) Read the next message as string
ExcerptTailer	toEnd() Wind to the last entry int eh last entry
ExcerptTailer	toStart() Replay from the first entry in the first cycle.

Method Detail

readDocument

boolean readDocument(@NotNull
                     net.openhft.chronicle.wire.ReadMarshallable reader)

Parameters:

reader - user to read the document

Returns:

true if successful

readBytes

boolean readBytes(@NotNull
                  net.openhft.chronicle.bytes.ReadBytesMarshallable marshallable)

Parameters:

marshallable - used to read the document

Returns:

true if successful

readBytes

boolean readBytes(@NotNull
                  net.openhft.chronicle.bytes.Bytes using)

Parameters:

using - used to read the document

Returns:

true if successful

readingDocument

default net.openhft.chronicle.wire.DocumentContext readingDocument()

equivalent to readDocument(ReadMarshallable) but with out the use of a lambda expression. This method is the ExcerptTailer equivalent of WireIn.readingDocument()

Returns:

the document context

readingDocument

net.openhft.chronicle.wire.DocumentContext readingDocument(boolean includeMetaData)

readText

String readText()

Read the next message as a String

Returns:

the String or null if there is none.

readText

boolean readText(StringBuilder sb)

Read the next message as string

Parameters:

sb - to copy the text into

Returns:

true if there was a message, or false if not.

index

long index()

Returns:

the index just read, this include the cycle and the sequence number from with this cycle

cycle

int cycle()

Returns:

the cycle this appender is on, usually with chronicle-queue each cycle will have its own unique data file to store the excerpt

moveToIndex

boolean moveToIndex(long index)
             throws TimeoutException

Randomly select an Excerpt.

Parameters:

index - index to look up, the index includes the cycle number and a sequence number from with this cycle

Returns:

true if this is a valid entries.

Throws:

TimeoutException

toStart

@NotNull
ExcerptTailer toStart()

Replay from the first entry in the first cycle.

Returns:

this Excerpt

toEnd

@NotNull
ExcerptTailer toEnd()

Wind to the last entry int eh last entry

If the direction() == FORWARD, this will be 1 more than the last entry.
Otherwise the index will be the last entry.

Returns:

this Excerpt

direction

TailerDirection direction()

Returns:

the direction of movement after reading an entry.

direction

ExcerptTailer direction(TailerDirection direction)

Set the direction of movement.

Parameters:

direction - NONE, FORWARD, BACKWARD

Returns:

this

methodReader

default MethodReader methodReader(Object... objects)

Reads messages from this tails as methods. It returns a BooleanSupplier which returns

Parameters:

objects - which implement the methods serialized to the file.

Returns:

a reader which will read one Excerpt at a time

readMap

default Map<String,Object> readMap()

Read a Map>String, Object> from the content.

Returns:

the Map, or null if no message is waiting.

afterLastWritten

ExcerptTailer afterLastWritten(ChronicleQueue queue)
                        throws net.openhft.chronicle.core.io.IORuntimeException

Wind this tailer to after the last entry which wrote an entry to the queue

Parameters:

queue - which was written to.

Returns:

this ExcerptTailer

Throws:

net.openhft.chronicle.core.io.IORuntimeException - if the queue couldn't be wound to the last index.