net.openhft.chronicle.queue

Interface ChronicleQueue

All Superinterfaces:

AutoCloseable, Closeable

All Known Subinterfaces:

RollingChronicleQueue

All Known Implementing Classes:

SingleChronicleQueue

public interface ChronicleQueue
extends net.openhft.chronicle.core.io.Closeable

Chronicle (in a generic sense) is a Java project focused on building a persisted low latency messaging framework for high performance and critical applications.

Using non-heap storage options Chronicle provides a processing environment where applications does not suffer from GarbageCollection. GarbageCollection (GC) may slow down your critical operations non-deterministically at any time.. In order to avoid non-determinism and escape from GC delays off-heap memory solutions are addressed. The main idea is to manage your memory manually so does not suffer from GC. Chronicle behaves like a management interface over off-heap memory so you can build your own solutions over it.

Chronicle uses RandomAccessFiles while managing memory and this choice brings lots of possibility. Random access files permit non-sequential, or random, access to a file's contents. To access a file randomly, you open the file, seek a particular location, and read from or writeBytes to that file. RandomAccessFiles can be seen as "large" C-type byte arrays that you can access any random index "directly" using pointers. File portions can be used as ByteBuffers if the portion is mapped into memory.

ChronicleQueue (now in the specific sense) is the main interface for management and can be seen as the "Collection class" of the Chronicle environment. You will reserve a portion of memory and then put/fetch/update records using the ChronicleQueue interface.

ExcerptCommon is the main data container in a ChronicleQueue, each Chronicle is composed of Excerpts. Putting data to a queue means starting a new Excerpt, writing data into it and finishing the Excerpt at the upper.

While ExcerptCommon is a generic purpose container allowing for remote access, it also has more specialized counterparts for sequential operations. See ExcerptTailer and ExcerptAppender

Author:

peter.lawrey

Field Summary

Fields

Modifier and Type	Field and Description
static int	TEST_BLOCK_SIZE

Method Summary

Modifier and Type	Method and Description
ExcerptAppender	acquireAppender() An Appender can be used to writeBytes new excerpts sequentially to the upper.
void	clear() Remove all the entries in the queue.
default ExcerptAppender	createAppender() Deprecated. to be remove in version 4.6 or later use acquireAppender()
ExcerptTailer	createTailer()
String	dump() Dump a Queue in YAML format.
default void	dump(OutputStream stream, long fromIndex, long toIndex)
void	dump(Writer writer, long fromIndex, long toIndex) Dump a range of entries to a Writer
File	file()
long	firstIndex()
long	lastAcknowledgedIndexReplicated()
default <T> T	methodWriter(Class<T> tClass, Class... additional)
default <T> net.openhft.chronicle.wire.VanillaMethodWriterBuilder<T>	methodWriterBuilder(Class<T> tClass)
default int	numberOfReferences(File queueFile)
int	sourceId()
net.openhft.chronicle.wire.WireType	wireType()

Methods inherited from interface net.openhft.chronicle.core.io.Closeable

close, closeQuietly, closeQuietly, isClosed, notifyClosing

Field Detail

TEST_BLOCK_SIZE

static final int TEST_BLOCK_SIZE

See Also:

Constant Field Values

Method Detail

createTailer

@NotNull
ExcerptTailer createTailer()

Returns:

a new ExcerptTailer to read sequentially.

acquireAppender

@NotNull
ExcerptAppender acquireAppender()

An Appender can be used to writeBytes new excerpts sequentially to the upper.

Returns:

A thread local Appender for writing new entries to the end.

createAppender

@NotNull
 @Deprecated
default ExcerptAppender createAppender()

Deprecated. to be remove in version 4.6 or later use acquireAppender()

firstIndex

long firstIndex()

Returns:

the lowest valid index available, or Long.MAX_VALUE if none are found

wireType

@NotNull
net.openhft.chronicle.wire.WireType wireType()

Returns:

the type of wire used, for example WireTypes.TEXT or WireTypes.BINARY

clear

void clear()

Remove all the entries in the queue.

file

@NotNull
File file()

Returns:

the base file where ChronicleQueue stores its data.

dump

@NotNull
String dump()

Dump a Queue in YAML format.

Returns:

the contents of the Queue as YAML.

dump

void dump(Writer writer,
          long fromIndex,
          long toIndex)

Dump a range of entries to a Writer

Parameters:

writer - to write to

fromIndex - first index to include

toIndex - last index to include.

dump

default void dump(@NotNull
                  OutputStream stream,
                  long fromIndex,
                  long toIndex)

sourceId

int sourceId()

methodWriter

default <T> T methodWriter(@NotNull
                           Class<T> tClass,
                           Class... additional)

methodWriterBuilder

@NotNull
default <T> net.openhft.chronicle.wire.VanillaMethodWriterBuilder<T> methodWriterBuilder(@NotNull
                                                                                                  Class<T> tClass)

numberOfReferences

default int numberOfReferences(File queueFile)

lastAcknowledgedIndexReplicated

long lastAcknowledgedIndexReplicated()