io.aeron.driver.status

Class StreamCounter

java.lang.Object

io.aeron.driver.status.StreamCounter

public class StreamCounter
extends Object

Allocates counters on a stream of messages.

Positions tracked in bytes include:

• PublisherPos: Highest position on a Publication reached for offers and claims as an approximation sampled once per second.
• PublisherLimit: Limit for flow controlling a Publication offers and claims.
• SenderPos: Highest position on a Publication stream sent to the media.
• SenderLimit: Limit for flow controlling a Sender of a stream.
• ReceiverHwm: Highest position observed by the Receiver when rebuilding an Image of a stream.
• ReceiverPos: Highest contiguous position rebuilt by the Receiver on an Image of a stream.
• SubscriberPos: Consumption position on an Image of a stream by individual Subscriber.

Note: All counters are real-time with the exception of PublisherPos which is sampled once per second which means it can appear to be behind.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CHANNEL_OFFSET Offset in the key meta data for the channel of the counter.
static int	MAX_CHANNEL_LENGTH The maximum length in bytes of the encoded channel identity.
static int	REGISTRATION_ID_OFFSET Offset in the key meta data for the registration id of the counter.
static int	SESSION_ID_OFFSET Offset in the key meta data for the session id of the counter.
static int	STREAM_ID_OFFSET Offset in the key meta data for the stream id of the counter.

Constructor Summary

Constructors

Constructor and Description
StreamCounter()

Method Summary

Modifier and Type	Method and Description
static UnsafeBufferPosition	allocate(MutableDirectBuffer tempBuffer, String name, int typeId, CountersManager countersManager, long registrationId, int sessionId, int streamId, String channel) Allocate a counter for tracking a position on a stream of messages.
static UnsafeBufferPosition	allocate(MutableDirectBuffer tempBuffer, String name, int typeId, CountersManager countersManager, long registrationId, int sessionId, int streamId, String channel, long joinPosition) Allocate a counter for tracking a position on a stream of messages.
static int	allocateCounterId(MutableDirectBuffer tempBuffer, String name, int typeId, CountersManager countersManager, long registrationId, int sessionId, int streamId, String channel) Allocate a counter id for tracking a position on a stream of messages.
static String	labelName(int typeId) Return the label name for a counter type identifier.

Methods inherited from class java.lang.Object

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

Field Detail

REGISTRATION_ID_OFFSET

public static final int REGISTRATION_ID_OFFSET

Offset in the key meta data for the registration id of the counter.

See Also:

Constant Field Values

SESSION_ID_OFFSET

public static final int SESSION_ID_OFFSET

Offset in the key meta data for the session id of the counter.

See Also:

Constant Field Values

STREAM_ID_OFFSET

public static final int STREAM_ID_OFFSET

Offset in the key meta data for the stream id of the counter.

See Also:

Constant Field Values

CHANNEL_OFFSET

public static final int CHANNEL_OFFSET

Offset in the key meta data for the channel of the counter.

See Also:

Constant Field Values

MAX_CHANNEL_LENGTH

public static final int MAX_CHANNEL_LENGTH

The maximum length in bytes of the encoded channel identity.

See Also:

Constant Field Values

Constructor Detail

StreamCounter

public StreamCounter()

Method Detail

allocate

public static UnsafeBufferPosition allocate(MutableDirectBuffer tempBuffer,
                                            String name,
                                            int typeId,
                                            CountersManager countersManager,
                                            long registrationId,
                                            int sessionId,
                                            int streamId,
                                            String channel)

Allocate a counter for tracking a position on a stream of messages.

Parameters:

tempBuffer - to be used for labels and key.

name - of the counter for the label.

typeId - of the counter for classification.

countersManager - from which to allocated the underlying storage.

registrationId - to be associated with the counter.

sessionId - for the stream of messages.

streamId - for the stream of messages.

channel - for the stream of messages.

Returns:

a new UnsafeBufferPosition for tracking the stream.

allocateCounterId

public static int allocateCounterId(MutableDirectBuffer tempBuffer,
                                    String name,
                                    int typeId,
                                    CountersManager countersManager,
                                    long registrationId,
                                    int sessionId,
                                    int streamId,
                                    String channel)

Allocate a counter id for tracking a position on a stream of messages.

Parameters:

tempBuffer - to be used for labels and key.

name - of the counter for the label.

typeId - of the counter for classification.

countersManager - from which to allocated the underlying storage.

registrationId - to be associated with the counter.

sessionId - for the stream of messages.

streamId - for the stream of messages.

channel - for the stream of messages.

Returns:

the id of the allocated counter.

allocate

public static UnsafeBufferPosition allocate(MutableDirectBuffer tempBuffer,
                                            String name,
                                            int typeId,
                                            CountersManager countersManager,
                                            long registrationId,
                                            int sessionId,
                                            int streamId,
                                            String channel,
                                            long joinPosition)

Allocate a counter for tracking a position on a stream of messages.

Parameters:

tempBuffer - to be used for labels and key.

name - of the counter for the label.

typeId - of the counter for classification.

countersManager - from which to allocated the underlying storage.

registrationId - to be associated with the counter.

sessionId - for the stream of messages.

streamId - for the stream of messages.

channel - for the stream of messages.

joinPosition - for the label.

Returns:

a new UnsafeBufferPosition for tracking the stream.

labelName

public static String labelName(int typeId)

Return the label name for a counter type identifier.

Parameters:

typeId - of the counter.

Returns:

the label name as a String.