Backend RingBuffer

Ring Buffer Backend

RingBufferBackend is an in-memory backend that keeps only the last N formatted records.

It is intended for diagnostics, tests, and recent-history capture where keeping the complete log stream is unnecessary.

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Behavior

Implementation behavior:

• each accepted record is formatted using the owner channel’s OutputFlags
• records are stored as strings
• appending is protected by an internal mutex
• when the record count exceeds max-items, the oldest records are removed
• Join() returns the current ring content as one string
• Clear() drops the current records

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Configuration

RingBufferBackendConfig::Parse() supports:

• max-items — positive integer number of records to keep

Example:

{
  "type": "RingBufferBackend",
  "max-items": 200
}

max-items must be greater than zero.

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Runtime control

The backend command accepts the type names ringbuffer, ring, and rbuf:

logmectl -p 9010 backend --channel net --add ring --max-items 200

--max-items applies only to RingBufferBackend.

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Relationship to BufferBackend

BufferBackend and RingBufferBackend are both memory backends, but they solve different problems:

• BufferBackend stores a byte buffer and is useful for delayed persistence or complete in-memory capture.
• RingBufferBackend stores the last N records and is useful for recent-history diagnostics.

See Recent-History Capture for the diagnostic pattern built on top of this backend.