Method Seek

pkg/querier/batch/batch.go:94–136

Seek implements chunkenc.Iterator.

(t int64)

// Seek implements chunkenc.Iterator.
func (a *iteratorAdapter) Seek(t int64) chunkenc.ValueType {

	// Optimisation: fulfill the seek using current batch if possible.
	if a.curr.Length > 0 && a.curr.Index < a.curr.Length {
		if t <= a.curr.Timestamps[a.curr.Index] {
			//In this case, the interface's requirement is met, so state of this
			//iterator does not need any change.
			return a.curr.ValType
		} else if t <= a.curr.Timestamps[a.curr.Length-1] {
			//In this case, some timestamp between current sample and end of batch can fulfill
			//the seek. Let's find it.
			for a.curr.Index < a.curr.Length && t > a.curr.Timestamps[a.curr.Index] {
				a.curr.Index++
			}
			return a.curr.ValType
		} else if t <= a.underlying.MaxCurrentChunkTime() {
			// In this case, some timestamp inside the current underlying chunk can fulfill the seek.
			// In this case we will call next until we find the sample as it will be faster than calling
			// `a.underlying.Seek` directly as this would cause the iterator to start from the beginning of the chunk.
			// See: https://github.com/cortexproject/cortex/blob/f69452975877c67ac307709e5f60b8d20477764c/pkg/querier/batch/chunk.go#L26-L45
			//      https://github.com/cortexproject/cortex/blob/f69452975877c67ac307709e5f60b8d20477764c/pkg/chunk/encoding/prometheus_chunk.go#L90-L95
			for {
				valType := a.Next()
				if valType == chunkenc.ValNone {
					break
				}
				if t <= a.curr.Timestamps[a.curr.Index] {
					return valType
				}
			}
		}
	}

	a.curr.Length = -1
	a.batchSize = 1
	if valType := a.underlying.Seek(t, a.batchSize); valType != chunkenc.ValNone {
		a.curr = a.underlying.Batch()
		if a.curr.Index < a.curr.Length {
			return a.curr.ValType
		}
	}
	return chunkenc.ValNone
}

// Next implements chunkenc.Iterator.
func (a *iteratorAdapter) Next() chunkenc.ValueType {