[query] Offset function (#1561)

* [query] Offset function

* PR response: remove wrapper block

* remove defer

* Fix test

src/query/block/offset.go

@@ -0,0 +1,268 @@
+// Copyright (c) 2018 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package block
+
+import (
+	"time"
+
+	"github.com/m3db/m3/src/query/ts"
+)
+
+func updateMeta(meta Metadata, offset time.Duration) Metadata {
+	meta.Bounds.Start = meta.Bounds.Start.Add(offset)
+	return meta
+}
+
+type offsetBlock struct {
+	block  Block
+	offset time.Duration
+}
+
+// NewOffsetBlock creates an offset block wrapping another block with an offset.
+func NewOffsetBlock(block Block, offset time.Duration) Block {
+	// NB: this is an invalid case; however, if offset is invalid, it's safe to
+	// return the base block instead.
+	if offset <= 0 {
+		return block
+	}
+
+	return &offsetBlock{
+		block:  block,
+		offset: offset,
+	}
+}
+
+func (b *offsetBlock) Close() error { return b.block.Close() }
+
+func (b *offsetBlock) WithMetadata(
+	meta Metadata,
+	sm []SeriesMeta,
+) (Block, error) {
+	bl, err := b.block.WithMetadata(meta, sm)
+	if err != nil {
+		return nil, err
+	}
+
+	b.block = bl
+	return b, nil
+}
+
+// StepIter returns a StepIterator
+func (b *offsetBlock) StepIter() (StepIter, error) {
+	iter, err := b.block.StepIter()
+	if err != nil {
+		return nil, err
+	}
+
+	return &offsetStepIter{
+		it:     iter,
+		offset: b.offset,
+	}, nil
+}
+
+type offsetStepIter struct {
+	it     StepIter
+	offset time.Duration
+}
+
+func (it *offsetStepIter) Close()                   { it.it.Close() }
+func (it *offsetStepIter) Err() error               { return it.it.Err() }
+func (it *offsetStepIter) StepCount() int           { return it.it.StepCount() }
+func (it *offsetStepIter) SeriesMeta() []SeriesMeta { return it.it.SeriesMeta() }
+func (it *offsetStepIter) Next() bool               { return it.it.Next() }
+
+func (it *offsetStepIter) Meta() Metadata {
+	return updateMeta(it.it.Meta(), it.offset)
+}
+
+func (it *offsetStepIter) Current() Step {
+	c := it.it.Current()
+	return ColStep{
+		time:   c.Time().Add(it.offset),
+		values: c.Values(),
+	}
+}
+
+// SeriesIter returns a SeriesIterator
+func (b *offsetBlock) SeriesIter() (SeriesIter, error) {
+	iter, err := b.block.SeriesIter()
+	if err != nil {
+		return nil, err
+	}
+
+	return &offsetSeriesIter{
+		it:     iter,
+		offset: b.offset,
+	}, nil
+}
+
+type offsetSeriesIter struct {
+	it     SeriesIter
+	offset time.Duration
+}
+
+func (it *offsetSeriesIter) Close()                   { it.it.Close() }
+func (it *offsetSeriesIter) Err() error               { return it.it.Err() }
+func (it *offsetSeriesIter) SeriesCount() int         { return it.it.SeriesCount() }
+func (it *offsetSeriesIter) SeriesMeta() []SeriesMeta { return it.it.SeriesMeta() }
+func (it *offsetSeriesIter) Next() bool               { return it.it.Next() }
+func (it *offsetSeriesIter) Current() Series          { return it.it.Current() }
+func (it *offsetSeriesIter) Meta() Metadata {
+	return updateMeta(it.it.Meta(), it.offset)
+}
+
+// Unconsolidated returns the unconsolidated version for the block
+func (b *offsetBlock) Unconsolidated() (UnconsolidatedBlock, error) {
+	unconsolidated, err := b.block.Unconsolidated()
+	if err != nil {
+		return nil, err
+	}
+
+	return &ucOffsetBlock{
+		block:  unconsolidated,
+		offset: b.offset,
+	}, nil
+}
+
+type ucOffsetBlock struct {
+	block  UnconsolidatedBlock
+	offset time.Duration
+}
+
+func (b *ucOffsetBlock) Close() error { return b.block.Close() }
+
+func (b *ucOffsetBlock) WithMetadata(
+	meta Metadata,
+	sm []SeriesMeta,
+) (UnconsolidatedBlock, error) {
+	bl, err := b.block.WithMetadata(meta, sm)
+	if err != nil {
+		return nil, err
+	}
+
+	b.block = bl
+	return b, nil
+}
+
+func (b *ucOffsetBlock) Consolidate() (Block, error) {
+	block, err := b.block.Consolidate()
+	if err != nil {
+		return nil, err
+	}
+
+	return &offsetBlock{
+		block:  block,
+		offset: b.offset,
+	}, nil
+}
+
+func (b *ucOffsetBlock) StepIter() (UnconsolidatedStepIter, error) {
+	iter, err := b.block.StepIter()
+	if err != nil {
+		return nil, err
+	}
+
+	return &ucOffsetStepIter{
+		it:     iter,
+		offset: b.offset,
+	}, nil
+}
+
+type ucOffsetStepIter struct {
+	it     UnconsolidatedStepIter
+	offset time.Duration
+}
+
+func (it *ucOffsetStepIter) Close()                   { it.it.Close() }
+func (it *ucOffsetStepIter) Err() error               { return it.it.Err() }
+func (it *ucOffsetStepIter) StepCount() int           { return it.it.StepCount() }
+func (it *ucOffsetStepIter) SeriesMeta() []SeriesMeta { return it.it.SeriesMeta() }
+func (it *ucOffsetStepIter) Next() bool               { return it.it.Next() }
+
+func (it *ucOffsetStepIter) Meta() Metadata {
+	return updateMeta(it.it.Meta(), it.offset)
+}
+
+type unconsolidatedStep struct {
+	time   time.Time
+	values []ts.Datapoints
+}
+
+// Time for the step.
+func (s unconsolidatedStep) Time() time.Time {
+	return s.time
+}
+
+// Values for the column.
+func (s unconsolidatedStep) Values() []ts.Datapoints {
+	return s.values
+}
+
+func (it *ucOffsetStepIter) Current() UnconsolidatedStep {
+	c := it.it.Current()
+	for _, val := range c.Values() {
+		for i, dp := range val.Datapoints() {
+			val[i].Timestamp = dp.Timestamp.Add(it.offset)
+		}
+	}
+
+	return unconsolidatedStep{
+		time:   c.Time().Add(it.offset),
+		values: c.Values(),
+	}
+}
+
+func (b *ucOffsetBlock) SeriesIter() (UnconsolidatedSeriesIter, error) {
+	seriesIter, err := b.block.SeriesIter()
+	if err != nil {
+		return nil, err
+	}
+
+	return &ucOffsetSeriesIter{
+		it:     seriesIter,
+		offset: b.offset,
+	}, nil
+}
+
+type ucOffsetSeriesIter struct {
+	it     UnconsolidatedSeriesIter
+	offset time.Duration
+}
+
+func (it *ucOffsetSeriesIter) Close()                   { it.it.Close() }
+func (it *ucOffsetSeriesIter) Err() error               { return it.it.Err() }
+func (it *ucOffsetSeriesIter) SeriesCount() int         { return it.it.SeriesCount() }
+func (it *ucOffsetSeriesIter) SeriesMeta() []SeriesMeta { return it.it.SeriesMeta() }
+func (it *ucOffsetSeriesIter) Next() bool               { return it.it.Next() }
+func (it *ucOffsetSeriesIter) Current() UnconsolidatedSeries {
+	c := it.it.Current()
+	for _, val := range c.datapoints {
+		for i, dp := range val.Datapoints() {
+			val[i].Timestamp = dp.Timestamp.Add(it.offset)
+		}
+	}
+
+	return c
+}
+
+func (it *ucOffsetSeriesIter) Meta() Metadata {
+	return updateMeta(it.it.Meta(), it.offset)
+}