io.aeron.driver.reports

Class LossReport

java.lang.Object

io.aeron.driver.reports.LossReport

public class LossReport
extends java.lang.Object

A report of loss events on a message stream.

The provided AtomicBuffer can wrap a memory-mapped file so logging can be out of process. This provides the benefit that if a crash or lockup occurs then the log can be read externally without loss of data.

Note:This class is NOT threadsafe to be used from multiple logging threads.

The error records are recorded to the memory mapped buffer in the following format.

   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
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |R|                    Observation Count                        |
  |                                                               |
  +-+-------------------------------------------------------------+
  |R|                     Total Bytes Lost                        |
  |                                                               |
  +---------------------------------------------------------------+
  |                 First Observation Timestamp                   |
  |                                                               |
  +---------------------------------------------------------------+
  |                  Last Observation Timestamp                   |
  |                                                               |
  +---------------------------------------------------------------+
  |                          Session ID                           |
  +---------------------------------------------------------------+
  |                           Stream ID                           |
  +---------------------------------------------------------------+
  |                 Channel encoded in US-ASCII                  ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                  Source encoded in US-ASCII                  ...
 ...                                                              |
  +---------------------------------------------------------------+
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LossReport.ReportEntry Report entry for a specific stream.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CHANNEL_OFFSET Offset within an entry at which the channel field begins.
static int	ENTRY_ALIGNMENT Alignment to be applied for each entry offset.
static int	FIRST_OBSERVATION_OFFSET Offset within an entry at which the first observation field begins.
static int	LAST_OBSERVATION_OFFSET Offset within an entry at which the last observation field begins.
static int	OBSERVATION_COUNT_OFFSET Offset within an entry at which the observation count begins.
static int	SESSION_ID_OFFSET Offset within an entry at which the session id field begins.
static int	STREAM_ID_OFFSET Offset within an entry at which the stream id field begins.
static int	TOTAL_BYTES_LOST_OFFSET Offset within an entry at which the total bytes field begins.

Constructor Summary

Constructors

Constructor and Description
LossReport(org.agrona.concurrent.AtomicBuffer buffer) Create a loss report which wraps a buffer which is ideally memory mapped so it can be read from another process.

Method Summary

Modifier and Type	Method and Description
LossReport.ReportEntry	createEntry(long initialBytesLost, long timestampMs, int sessionId, int streamId, java.lang.String channel, java.lang.String source) Create a new entry for recording loss on a given stream.

Methods inherited from class java.lang.Object

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

Field Detail

ENTRY_ALIGNMENT

public static final int ENTRY_ALIGNMENT

Alignment to be applied for each entry offset.

See Also:

Constant Field Values

OBSERVATION_COUNT_OFFSET

public static final int OBSERVATION_COUNT_OFFSET

Offset within an entry at which the observation count begins.

See Also:

Constant Field Values

TOTAL_BYTES_LOST_OFFSET

public static final int TOTAL_BYTES_LOST_OFFSET

Offset within an entry at which the total bytes field begins.

See Also:

Constant Field Values

FIRST_OBSERVATION_OFFSET

public static final int FIRST_OBSERVATION_OFFSET

Offset within an entry at which the first observation field begins.

See Also:

Constant Field Values

LAST_OBSERVATION_OFFSET

public static final int LAST_OBSERVATION_OFFSET

Offset within an entry at which the last observation field begins.

See Also:

Constant Field Values

SESSION_ID_OFFSET

public static final int SESSION_ID_OFFSET

Offset within an entry at which the session id field begins.

See Also:

Constant Field Values

STREAM_ID_OFFSET

public static final int STREAM_ID_OFFSET

Offset within an entry at which the stream id field begins.

See Also:

Constant Field Values

CHANNEL_OFFSET

public static final int CHANNEL_OFFSET

Offset within an entry at which the channel field begins.

See Also:

Constant Field Values

Constructor Detail

LossReport

public LossReport(org.agrona.concurrent.AtomicBuffer buffer)

Create a loss report which wraps a buffer which is ideally memory mapped so it can be read from another process.

Parameters:

buffer - to be wrapped.

Method Detail

createEntry

public LossReport.ReportEntry createEntry(long initialBytesLost,
                                          long timestampMs,
                                          int sessionId,
                                          int streamId,
                                          java.lang.String channel,
                                          java.lang.String source)

Create a new entry for recording loss on a given stream.

If not space is remaining in the error report then null is returned.

Parameters:

initialBytesLost - on the stream.

timestampMs - at which the first loss was observed.

sessionId - for the stream.

streamId - for the stream.

channel - for the stream.

source - of the stream.

Returns:

a new record or null if the error log has insufficient space.