org.agrona.concurrent.status

Class CountersReader

java.lang.Object

org.agrona.concurrent.status.CountersReader

Direct Known Subclasses:

CountersManager

public class CountersReader
extends java.lang.Object

Reads the counters metadata and values buffers. This class is threadsafe and can be used across threads. Values Buffer

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                        Counter Value                          |
  |                                                               |
  +---------------------------------------------------------------+
  |                     120 bytes of padding                     ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                   Repeats to end of buffer                   ...
  |                                                               |
 ...                                                              |
  +---------------------------------------------------------------+
 

Meta Data Buffer

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                        Record State                           |
  +---------------------------------------------------------------+
  |                          Type Id                              |
  +---------------------------------------------------------------+
  |                      120 bytes for key                       ...
 ...                                                              |
  +-+-------------------------------------------------------------+
  |R|                      Label Length                           |
  +-+-------------------------------------------------------------+
  |                  124 bytes of Label in UTF-8                 ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                   Repeats to end of buffer                   ...
  |                                                               |
 ...                                                              |
  +---------------------------------------------------------------+
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CountersReader.MetaData Callback function for consuming metadata records of counters.

Field Summary

Fields

Modifier and Type	Field and Description
static int	COUNTER_LENGTH Length of the space allocated to a counter that includes padding to avoid false sharing.
static int	FULL_LABEL_LENGTH Length of a counter label length including length prefix.
static int	KEY_OFFSET Offset in the record at which the key is stored.
static int	LABEL_OFFSET Offset in the record at which the label is stored.
static int	MAX_KEY_LENGTH Maximum length a key can be.
static int	MAX_LABEL_LENGTH Maximum length of a label not including its length prefix.
static int	METADATA_LENGTH Length of a meta data record in bytes.
protected AtomicBuffer	metaDataBuffer
static int	RECORD_ALLOCATED Record currently allocated for use..
static int	RECORD_RECLAIMED Record was active and now has been reclaimed.
static int	RECORD_UNUSED Record has not been used.
static int	TYPE_ID_OFFSET Offset in the record at which the type id field is stored.
protected AtomicBuffer	valuesBuffer

Constructor Summary

Constructors

Constructor and Description
CountersReader(AtomicBuffer metaDataBuffer, AtomicBuffer valuesBuffer) Construct a reader over buffers containing the values and associated metadata.

Method Summary

Modifier and Type	Method and Description
static int	counterOffset(int counterId) The offset in the counter buffer for a given counterId.
void	forEach(CountersReader.MetaData metaData) Iterate over all the metadata in the buffer.
void	forEach(IntObjConsumer<java.lang.String> consumer) Iterate over all labels in the label buffer.
long	getCounterValue(int counterId) Get the value for a given counter id as a volatile read.
AtomicBuffer	metaDataBuffer() Get the buffer containing the metadata for the counters.
static int	metaDataOffset(int counterId) The offset in the metadata buffer for a given id.
AtomicBuffer	valuesBuffer() Get the buffer containing the values for the counters.

Methods inherited from class java.lang.Object

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

Field Detail

RECORD_UNUSED

public static final int RECORD_UNUSED

Record has not been used.

See Also:

Constant Field Values

RECORD_ALLOCATED

public static final int RECORD_ALLOCATED

Record currently allocated for use..

See Also:

Constant Field Values

RECORD_RECLAIMED

public static final int RECORD_RECLAIMED

Record was active and now has been reclaimed.

See Also:

Constant Field Values

METADATA_LENGTH

public static final int METADATA_LENGTH

Length of a meta data record in bytes.

See Also:

Constant Field Values

TYPE_ID_OFFSET

public static final int TYPE_ID_OFFSET

Offset in the record at which the type id field is stored.

See Also:

Constant Field Values

KEY_OFFSET

public static final int KEY_OFFSET

Offset in the record at which the key is stored.

See Also:

Constant Field Values

LABEL_OFFSET

public static final int LABEL_OFFSET

Offset in the record at which the label is stored.

See Also:

Constant Field Values

FULL_LABEL_LENGTH

public static final int FULL_LABEL_LENGTH

Length of a counter label length including length prefix.

See Also:

Constant Field Values

MAX_LABEL_LENGTH

public static final int MAX_LABEL_LENGTH

Maximum length of a label not including its length prefix.

See Also:

Constant Field Values

MAX_KEY_LENGTH

public static final int MAX_KEY_LENGTH

Maximum length a key can be.

See Also:

Constant Field Values

COUNTER_LENGTH

public static final int COUNTER_LENGTH

Length of the space allocated to a counter that includes padding to avoid false sharing.

See Also:

Constant Field Values

metaDataBuffer

protected final AtomicBuffer metaDataBuffer

valuesBuffer

protected final AtomicBuffer valuesBuffer

Constructor Detail

CountersReader

public CountersReader(AtomicBuffer metaDataBuffer,
                      AtomicBuffer valuesBuffer)

Construct a reader over buffers containing the values and associated metadata.

Parameters:

metaDataBuffer - containing the counter metadata.

valuesBuffer - containing the counter values.

Method Detail

metaDataBuffer

public AtomicBuffer metaDataBuffer()

Get the buffer containing the metadata for the counters.

Returns:

the buffer containing the metadata for the counters.

valuesBuffer

public AtomicBuffer valuesBuffer()

Get the buffer containing the values for the counters.

Returns:

the buffer containing the values for the counters.

counterOffset

public static int counterOffset(int counterId)

The offset in the counter buffer for a given counterId.

Parameters:

counterId - for which the offset should be provided.

Returns:

the offset in the counter buffer.

metaDataOffset

public static int metaDataOffset(int counterId)

The offset in the metadata buffer for a given id.

Parameters:

counterId - for the record.

Returns:

the offset at which the metadata record begins.

forEach

public void forEach(IntObjConsumer<java.lang.String> consumer)

Iterate over all labels in the label buffer.

Parameters:

consumer - function to be called for each label.

forEach

public void forEach(CountersReader.MetaData metaData)

Iterate over all the metadata in the buffer.

Parameters:

metaData - function to be called for each metadata record.

getCounterValue

public long getCounterValue(int counterId)

Get the value for a given counter id as a volatile read.

Parameters:

counterId - to be read.

Returns:

the current value of the counter.