org.agrona.concurrent.ringbuffer

Interface RingBuffer

All Known Implementing Classes:

ManyToOneRingBuffer, OneToOneRingBuffer

public interface RingBuffer

Ring-buffer for the concurrent exchanging of binary encoded messages from producer(s) to consumer(s) in a FIFO manner.

Method Summary

Modifier and Type	Method and Description
AtomicBuffer	buffer() Get the underlying buffer used by the RingBuffer for storage.
int	capacity() Get the capacity of the ring-buffer in bytes for exchange.
long	consumerHeartbeatTime() The time of the last consumer heartbeat.
void	consumerHeartbeatTime(long time) Set the time of the last consumer heartbeat.
long	consumerPosition() The position in bytes from start up for the consumers.
int	maxMsgLength() The maximum message length in bytes supported by the underlying ring buffer.
long	nextCorrelationId() Get the next value that can be used for a correlation id on an message when a response needs to be correlated.
long	producerPosition() The position in bytes from start up of the producers.
int	read(MessageHandler handler) Read as many messages as are available to the end of the ring buffer.
int	read(MessageHandler handler, int messageCountLimit) Read as many messages as are available to end of the ring buffer to up a supplied maximum.
int	size() Size of the buffer backlog in bytes between producers and consumers.
boolean	unblock() Unblock a multi-producer ring buffer when a producer has died during the act of offering.
boolean	write(int msgTypeId, DirectBuffer srcBuffer, int srcIndex, int length) Non-blocking write of an message to an underlying ring-buffer.

Method Detail

capacity

int capacity()

Get the capacity of the ring-buffer in bytes for exchange.

Returns:

the capacity of the ring-buffer in bytes for exchange.

write

boolean write(int msgTypeId,
              DirectBuffer srcBuffer,
              int srcIndex,
              int length)

Non-blocking write of an message to an underlying ring-buffer.

Parameters:

msgTypeId - type of the message encoding.

srcBuffer - containing the encoded binary message.

srcIndex - at which the encoded message begins.

length - of the encoded message in bytes.

Returns:

true if written to the ring-buffer, or false if insufficient space exists.

Throws:

java.lang.IllegalArgumentException - if the length is greater than maxMsgLength()

read

int read(MessageHandler handler)

Read as many messages as are available to the end of the ring buffer.

If the ring buffer wraps or encounters a type of record, such a a padding record, then an implementation may choose to return and expect the caller to try again. The size() method may be called to determine of a backlog of message bytes remains in the ring buffer.

Parameters:

handler - to be called for processing each message in turn.

Returns:

the number of messages that have been processed.

read

int read(MessageHandler handler,
         int messageCountLimit)

Read as many messages as are available to end of the ring buffer to up a supplied maximum.

If the ring buffer wraps or encounters a type of record, such a a padding record, then an implementation may choose to return and expect the caller to try again. The size() method may be called to determine of a backlog of message bytes remains in the ring buffer.

Parameters:

handler - to be called for processing each message in turn.

messageCountLimit - the number of messages will be read in a single invocation.

Returns:

the number of messages that have been processed.

maxMsgLength

int maxMsgLength()

The maximum message length in bytes supported by the underlying ring buffer.

Returns:

the maximum message length in bytes supported by the underlying ring buffer.

nextCorrelationId

long nextCorrelationId()

Get the next value that can be used for a correlation id on an message when a response needs to be correlated.

This method should be thread safe.

Returns:

the next value in the correlation sequence.

buffer

AtomicBuffer buffer()

Get the underlying buffer used by the RingBuffer for storage.

Returns:

the underlying buffer used by the RingBuffer for storage.

consumerHeartbeatTime

void consumerHeartbeatTime(long time)

Set the time of the last consumer heartbeat.

Note: The value for time must be valid across processes which means System.nanoTime() is not a valid option.

Parameters:

time - of the last consumer heartbeat.

consumerHeartbeatTime

long consumerHeartbeatTime()

The time of the last consumer heartbeat.

Returns:

the time of the last consumer heartbeat.

producerPosition

long producerPosition()

The position in bytes from start up of the producers. The figure includes the headers. This is the range they are working with but could still be in the act of working with.

Returns:

number of bytes produced by the producers in claimed space.

consumerPosition

long consumerPosition()

The position in bytes from start up for the consumers. The figure includes the headers.

Returns:

the count of bytes consumed by the consumers.

size

int size()

Size of the buffer backlog in bytes between producers and consumers. The value includes the size of headers.

This method gives a concurrent snapshot of the buffer whereby a concurrent read or write may be partially complete and thus the value should be taken as an indication.

Returns:

size of the backlog of bytes in the buffer between producers and consumers.

unblock

boolean unblock()

Unblock a multi-producer ring buffer when a producer has died during the act of offering. The operation will scan from the consumer position up to the producer position.

If no action is required at the position then none will be taken.

Returns:

true of an unblocking action was taken otherwise false.