From 9b400b4c5884d8cd942d6c57b92f8b8159c7f4c0 Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Mon, 12 Dec 2016 19:12:55 +0100
Subject: [PATCH] Add chunk based series iterator

---
 querier.go | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 reader.go  | 13 ++++++++---
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/querier.go b/querier.go
index d64f6129a8..5cb6310dcb 100644
--- a/querier.go
+++ b/querier.go
@@ -1,5 +1,7 @@
 package tsdb
 
+import "github.com/fabxc/tsdb/chunks"
+
 // Matcher matches a string.
 type Matcher interface {
 	// Match returns true if the matcher applies to the string value.
@@ -52,3 +54,68 @@ type SeriesIterator interface {
 	// Err returns the current error.
 	Err() error
 }
+
+// chunkSeriesIterator implements a series iterator on top
+// of a list of time-sorted, non-overlapping chunks.
+type chunkSeriesIterator struct {
+	// minTimes []int64
+	chunks []chunks.Chunk
+
+	i   int
+	cur chunks.Iterator
+	err error
+}
+
+func newChunkSeriesIterator(cs []chunks.Chunk) *chunkSeriesIterator {
+	return &chunkSeriesIterator{
+		chunks: cs,
+		i:      0,
+		cur:    cs[0].Iterator(),
+	}
+}
+
+func (it *chunkSeriesIterator) Seek(t int64) (ok bool) {
+	// TODO(fabxc): skip to relevant chunk.
+	for it.Next() {
+		if ts, _ := it.Values(); ts >= t {
+			return true
+		}
+	}
+	return false
+}
+
+func (it *chunkSeriesIterator) Values() (t int64, v float64) {
+	return it.cur.Values()
+}
+
+func (it *chunkSeriesIterator) Next() bool {
+	if it.cur.Next() {
+		return true
+	}
+	if err := it.cur.Err(); err != nil {
+		return false
+	}
+	if it.i == len(it.chunks)-1 {
+		return false
+	}
+
+	it.i++
+	it.cur = it.chunks[it.i].Iterator()
+
+	return it.Next()
+}
+
+func (it *chunkSeriesIterator) Err() error {
+	return it.cur.Err()
+}
+
+type bufferedSeriesIterator struct {
+	// TODO(fabxc): time-based look back buffer for time-aggregating
+	// queries such as rate. It should allow us to re-use an iterator
+	// within a range query while calculating time-aggregates at any point.
+	//
+	// It also allows looking up/seeking at-or-before without modifying
+	// the simpler interface.
+	//
+	// Consider making this the main external interface.
+}
diff --git a/reader.go b/reader.go
index c4c5dd7211..ed7926c353 100644
--- a/reader.go
+++ b/reader.go
@@ -70,6 +70,8 @@ type StringTuples interface {
 }
 
 type indexReader struct {
+	series SeriesReader
+
 	// The underlying byte slice holding the encoded series data.
 	b []byte
 
@@ -83,11 +85,14 @@ var (
 	errInvalidFlag = fmt.Errorf("invalid flag")
 )
 
-func newIndexReader(b []byte) (*indexReader, error) {
+func newIndexReader(s SeriesReader, b []byte) (*indexReader, error) {
 	if len(b) < 16 {
 		return nil, errInvalidSize
 	}
-	r := &indexReader{b: b}
+	r := &indexReader{
+		series: s,
+		b:      b,
+	}
 
 	// Verify magic number.
 	if m := binary.BigEndian.Uint32(b[:4]); m != MagicIndex {
@@ -276,13 +281,15 @@ func (r *indexReader) Series(ref uint32) (Series, error) {
 	s := &series{
 		labels:  labels,
 		offsets: coffsets,
+		chunk:   r.series.Chunk,
 	}
 	return s, nil
 }
 
 type series struct {
 	labels  Labels
-	offsets []ChunkOffset
+	offsets []ChunkOffset // in-order chunk refs
+	chunk   func(ref uint32) (chunks.Chunk, error)
 }
 
 func (s *series) Labels() (Labels, error) {