Interface Iterator

tsdb/chunkenc/chunk.go:138–176

Iterator is a simple iterator that can only get the next value. Iterator iterates over the samples of a time series, in timestamp-increasing order.

// Iterator is a simple iterator that can only get the next value.
// Iterator iterates over the samples of a time series, in timestamp-increasing order.
type Iterator interface {
	// Next advances the iterator by one and returns the type of the value
	// at the new position (or ValNone if the iterator is exhausted).
	Next() ValueType
	// Seek advances the iterator forward to the first sample with a
	// timestamp equal or greater than t. If the current sample found by a
	// previous `Next` or `Seek` operation already has this property, Seek
	// has no effect. If a sample has been found, Seek returns the type of
	// its value. Otherwise, it returns ValNone, after which the iterator is
	// exhausted.
	Seek(t int64) ValueType
	// At returns the current timestamp/value pair if the value is a float.
	// Before the iterator has advanced, the behaviour is unspecified.
	At() (int64, float64)
	// AtHistogram returns the current timestamp/value pair if the value is a
	// histogram with integer counts. Before the iterator has advanced, the behaviour
	// is unspecified.
	// The method accepts an optional Histogram object which will be
	// reused when not nil. Otherwise, a new Histogram object will be allocated.
	AtHistogram(*histogram.Histogram) (int64, *histogram.Histogram)
	// AtFloatHistogram returns the current timestamp/value pair if the
	// value is a histogram with floating-point counts. It also works if the
	// value is a histogram with integer counts, in which case a
	// FloatHistogram copy of the histogram is returned. Before the iterator
	// has advanced, the behaviour is unspecified.
	// The method accepts an optional FloatHistogram object which will be
	// reused when not nil. Otherwise, a new FloatHistogram object will be allocated.
	AtFloatHistogram(*histogram.FloatHistogram) (int64, *histogram.FloatHistogram)
	// AtT returns the current timestamp.
	// Before the iterator has advanced, the behaviour is unspecified.
	AtT() int64
	// AtST returns the current start timestamp.
	// Returns 0 if the start timestamp is not implemented or not set.
	// Before the iterator has advanced, the behaviour is unspecified.
	AtST() int64
	// Err returns the current error. It should be used only after the
	// iterator is exhausted, i.e. `Next` or `Seek` have returned ValNone.
	Err() error
}

// ValueType defines the type of a value an Iterator points to.
type ValueType uint8