data

type Datalog interface {
	Initializer

	// Seeks the position and fills the buffer with chunks until maxSize or maxRecords is reached.
	// Opens and close the file handle. It may issue several reads to reach to the position.
	ReadFileFrom(
		buf []byte,
		maxSize int,
		segmentId int64,
		startOffset int64,
		maxRecords int,
		topic *TopicDataId,
	) ([]byte, error)

	// Blocks until there's an available buffer to be used to stream.
	// After use, it should be released
	StreamBuffer() []byte

	// Releases the stream buffer
	ReleaseStreamBuffer(buf []byte)

	// Gets the max producer offset from local.
	// Returns an error when not found.
	ReadProducerOffset(topicId *TopicDataId) (int64, error)

	// Gets a sorted list of offsets representing the name of the segment files, where the offset is less than maxOffset
	SegmentFileList(topic *TopicDataId, maxOffset int64) ([]int64, error)
}

type LocalWriteItem interface {
	SegmentChunk
	Replication() ReplicationInfo
	SetResult(error)
}

type ReadItem interface {
	Origin() string   // An identifier of the source of the poll used to determine whether the reader should use the last stored offset and not auto commit
	CommitOnly() bool // Determines whether it should only commit and not read as part of this request
	SetResult(error, SegmentChunk)
}

type ReadSegmentChunk struct {
	Buffer []byte
	Start  int64  // The offset of the first message
	Length uint32 // The amount of messages in the chunk
}

type ReplicationDataItem interface {
	SegmentChunk
	SegmentId() int64
	SetResult(error)
}

type ReplicationReader interface {
	MergeFileStructure() (bool, error) // Merge the index files content and file structures

	// Reads at least a chunk from a replica and returns the amount of bytes written in the buffer
	StreamFile(
		segmentId int64,
		topic *TopicDataId,
		startOffset int64,
		maxRecords int,
		buf []byte) (int, error)
}

type SegmentReader struct {
	Items chan ReadItem

	Topic                 TopicDataId
	TopicRangeClusterSize int
	SourceVersion         GenId // The version in which this reader was created, a consumer might be on Gen=v3 but the current is v4. In this case, source would be v4 and topic.Version = v3

	MaxProducedOffset *int64 // When set, it determines the last offset produced for this topicId for an old generation, inclusive
	// contains filtered or unexported fields
}

type SegmentWriter struct {
	Items chan SegmentChunk
	Topic TopicDataId
	// contains filtered or unexported fields
}