prometheus/db_test.go
Bartek Plotka a9b28a6aa0 db: Added tests for validateBlockSequence to confirm a bug.
(That's why test fails)

Signed-off-by: Bartek Plotka <bwplotka@gmail.com>
2018-03-28 15:50:52 +01:00

938 lines
21 KiB
Go

// Copyright 2017 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tsdb
import (
"io/ioutil"
"math"
"math/rand"
"os"
"sort"
"testing"
"github.com/pkg/errors"
"github.com/prometheus/tsdb/labels"
"github.com/prometheus/tsdb/testutil"
)
func openTestDB(t testing.TB, opts *Options) (db *DB, close func()) {
tmpdir, err := ioutil.TempDir("", "test")
testutil.Ok(t, err)
db, err = Open(tmpdir, nil, nil, opts)
testutil.Ok(t, err)
// Do not close the test database by default as it will deadlock on test failures.
return db, func() { os.RemoveAll(tmpdir) }
}
// query runs a matcher query against the querier and fully expands its data.
func query(t testing.TB, q Querier, matchers ...labels.Matcher) map[string][]sample {
ss, err := q.Select(matchers...)
testutil.Ok(t, err)
result := map[string][]sample{}
for ss.Next() {
series := ss.At()
samples := []sample{}
it := series.Iterator()
for it.Next() {
t, v := it.At()
samples = append(samples, sample{t: t, v: v})
}
testutil.Ok(t, it.Err())
name := series.Labels().String()
result[name] = samples
}
testutil.Ok(t, ss.Err())
return result
}
func TestDataAvailableOnlyAfterCommit(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
_, err := app.Add(labels.FromStrings("foo", "bar"), 0, 0)
testutil.Ok(t, err)
querier, err := db.Querier(0, 1)
testutil.Ok(t, err)
seriesSet := query(t, querier, labels.NewEqualMatcher("foo", "bar"))
testutil.Equals(t, seriesSet, map[string][]sample{})
testutil.Ok(t, querier.Close())
err = app.Commit()
testutil.Ok(t, err)
querier, err = db.Querier(0, 1)
testutil.Ok(t, err)
defer querier.Close()
seriesSet = query(t, querier, labels.NewEqualMatcher("foo", "bar"))
testutil.Equals(t, seriesSet, map[string][]sample{`{foo="bar"}`: []sample{{t: 0, v: 0}}})
}
func TestDataNotAvailableAfterRollback(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
_, err := app.Add(labels.FromStrings("foo", "bar"), 0, 0)
testutil.Ok(t, err)
err = app.Rollback()
testutil.Ok(t, err)
querier, err := db.Querier(0, 1)
testutil.Ok(t, err)
defer querier.Close()
seriesSet := query(t, querier, labels.NewEqualMatcher("foo", "bar"))
testutil.Equals(t, seriesSet, map[string][]sample{})
}
func TestDBAppenderAddRef(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app1 := db.Appender()
ref1, err := app1.Add(labels.FromStrings("a", "b"), 123, 0)
testutil.Ok(t, err)
// Reference should already work before commit.
err = app1.AddFast(ref1, 124, 1)
testutil.Ok(t, err)
err = app1.Commit()
testutil.Ok(t, err)
app2 := db.Appender()
// first ref should already work in next transaction.
err = app2.AddFast(ref1, 125, 0)
testutil.Ok(t, err)
ref2, err := app2.Add(labels.FromStrings("a", "b"), 133, 1)
testutil.Ok(t, err)
testutil.Assert(t, ref1 == ref2, "")
// Reference must be valid to add another sample.
err = app2.AddFast(ref2, 143, 2)
testutil.Ok(t, err)
err = app2.AddFast(9999999, 1, 1)
testutil.Equals(t, errors.Cause(err), ErrNotFound)
testutil.Ok(t, app2.Commit())
q, err := db.Querier(0, 200)
testutil.Ok(t, err)
res := query(t, q, labels.NewEqualMatcher("a", "b"))
testutil.Equals(t, map[string][]sample{
labels.FromStrings("a", "b").String(): []sample{
{t: 123, v: 0},
{t: 124, v: 1},
{t: 125, v: 0},
{t: 133, v: 1},
{t: 143, v: 2},
},
}, res)
testutil.Ok(t, q.Close())
}
func TestDeleteSimple(t *testing.T) {
numSamples := int64(10)
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
smpls := make([]float64, numSamples)
for i := int64(0); i < numSamples; i++ {
smpls[i] = rand.Float64()
app.Add(labels.Labels{{"a", "b"}}, i, smpls[i])
}
testutil.Ok(t, app.Commit())
cases := []struct {
intervals Intervals
remaint []int64
}{
{
intervals: Intervals{{1, 3}, {4, 7}},
remaint: []int64{0, 8, 9},
},
}
Outer:
for _, c := range cases {
// TODO(gouthamve): Reset the tombstones somehow.
// Delete the ranges.
for _, r := range c.intervals {
testutil.Ok(t, db.Delete(r.Mint, r.Maxt, labels.NewEqualMatcher("a", "b")))
}
// Compare the result.
q, err := db.Querier(0, numSamples)
testutil.Ok(t, err)
res, err := q.Select(labels.NewEqualMatcher("a", "b"))
testutil.Ok(t, err)
expSamples := make([]sample, 0, len(c.remaint))
for _, ts := range c.remaint {
expSamples = append(expSamples, sample{ts, smpls[ts]})
}
expss := newListSeriesSet([]Series{
newSeries(map[string]string{"a": "b"}, expSamples),
})
if len(expSamples) == 0 {
testutil.Assert(t, res.Next() == false, "")
continue
}
for {
eok, rok := expss.Next(), res.Next()
testutil.Equals(t, eok, rok)
if !eok {
continue Outer
}
sexp := expss.At()
sres := res.At()
testutil.Equals(t, sexp.Labels(), sres.Labels())
smplExp, errExp := expandSeriesIterator(sexp.Iterator())
smplRes, errRes := expandSeriesIterator(sres.Iterator())
testutil.Equals(t, errExp, errRes)
testutil.Equals(t, smplExp, smplRes)
}
}
}
func TestAmendDatapointCausesError(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
_, err := app.Add(labels.Labels{}, 0, 0)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
app = db.Appender()
_, err = app.Add(labels.Labels{}, 0, 1)
testutil.Equals(t, ErrAmendSample, err)
testutil.Ok(t, app.Rollback())
}
func TestDuplicateNaNDatapointNoAmendError(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
_, err := app.Add(labels.Labels{}, 0, math.NaN())
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
app = db.Appender()
_, err = app.Add(labels.Labels{}, 0, math.NaN())
testutil.Ok(t, err)
}
func TestNonDuplicateNaNDatapointsCausesAmendError(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
_, err := app.Add(labels.Labels{}, 0, math.Float64frombits(0x7ff0000000000001))
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
app = db.Appender()
_, err = app.Add(labels.Labels{}, 0, math.Float64frombits(0x7ff0000000000002))
testutil.Equals(t, ErrAmendSample, err)
}
func TestSkippingInvalidValuesInSameTxn(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
// Append AmendedValue.
app := db.Appender()
_, err := app.Add(labels.Labels{{"a", "b"}}, 0, 1)
testutil.Ok(t, err)
_, err = app.Add(labels.Labels{{"a", "b"}}, 0, 2)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
// Make sure the right value is stored.
q, err := db.Querier(0, 10)
testutil.Ok(t, err)
ssMap := query(t, q, labels.NewEqualMatcher("a", "b"))
testutil.Equals(t, map[string][]sample{
labels.New(labels.Label{"a", "b"}).String(): []sample{{0, 1}},
}, ssMap)
testutil.Ok(t, q.Close())
// Append Out of Order Value.
app = db.Appender()
_, err = app.Add(labels.Labels{{"a", "b"}}, 10, 3)
testutil.Ok(t, err)
_, err = app.Add(labels.Labels{{"a", "b"}}, 7, 5)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
q, err = db.Querier(0, 10)
testutil.Ok(t, err)
ssMap = query(t, q, labels.NewEqualMatcher("a", "b"))
testutil.Equals(t, map[string][]sample{
labels.New(labels.Label{"a", "b"}).String(): []sample{{0, 1}, {10, 3}},
}, ssMap)
testutil.Ok(t, q.Close())
}
func TestDB_Snapshot(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
// append data
app := db.Appender()
mint := int64(1414141414000)
for i := 0; i < 1000; i++ {
_, err := app.Add(labels.FromStrings("foo", "bar"), mint+int64(i), 1.0)
testutil.Ok(t, err)
}
testutil.Ok(t, app.Commit())
testutil.Ok(t, app.Rollback())
// create snapshot
snap, err := ioutil.TempDir("", "snap")
testutil.Ok(t, err)
defer os.RemoveAll(snap)
testutil.Ok(t, db.Snapshot(snap, true))
testutil.Ok(t, db.Close())
// reopen DB from snapshot
db, err = Open(snap, nil, nil, nil)
testutil.Ok(t, err)
defer db.Close()
querier, err := db.Querier(mint, mint+1000)
testutil.Ok(t, err)
defer querier.Close()
// sum values
seriesSet, err := querier.Select(labels.NewEqualMatcher("foo", "bar"))
testutil.Ok(t, err)
sum := 0.0
for seriesSet.Next() {
series := seriesSet.At().Iterator()
for series.Next() {
_, v := series.At()
sum += v
}
testutil.Ok(t, series.Err())
}
testutil.Ok(t, seriesSet.Err())
testutil.Equals(t, sum, 1000.0)
}
func TestDB_SnapshotWithDelete(t *testing.T) {
numSamples := int64(10)
db, close := openTestDB(t, nil)
defer close()
app := db.Appender()
smpls := make([]float64, numSamples)
for i := int64(0); i < numSamples; i++ {
smpls[i] = rand.Float64()
app.Add(labels.Labels{{"a", "b"}}, i, smpls[i])
}
testutil.Ok(t, app.Commit())
cases := []struct {
intervals Intervals
remaint []int64
}{
{
intervals: Intervals{{1, 3}, {4, 7}},
remaint: []int64{0, 8, 9},
},
}
Outer:
for _, c := range cases {
// TODO(gouthamve): Reset the tombstones somehow.
// Delete the ranges.
for _, r := range c.intervals {
testutil.Ok(t, db.Delete(r.Mint, r.Maxt, labels.NewEqualMatcher("a", "b")))
}
// create snapshot
snap, err := ioutil.TempDir("", "snap")
testutil.Ok(t, err)
defer os.RemoveAll(snap)
testutil.Ok(t, db.Snapshot(snap, true))
testutil.Ok(t, db.Close())
// reopen DB from snapshot
db, err = Open(snap, nil, nil, nil)
testutil.Ok(t, err)
defer db.Close()
// Compare the result.
q, err := db.Querier(0, numSamples)
testutil.Ok(t, err)
defer q.Close()
res, err := q.Select(labels.NewEqualMatcher("a", "b"))
testutil.Ok(t, err)
expSamples := make([]sample, 0, len(c.remaint))
for _, ts := range c.remaint {
expSamples = append(expSamples, sample{ts, smpls[ts]})
}
expss := newListSeriesSet([]Series{
newSeries(map[string]string{"a": "b"}, expSamples),
})
if len(expSamples) == 0 {
testutil.Assert(t, res.Next() == false, "")
continue
}
for {
eok, rok := expss.Next(), res.Next()
testutil.Equals(t, eok, rok)
if !eok {
continue Outer
}
sexp := expss.At()
sres := res.At()
testutil.Equals(t, sexp.Labels(), sres.Labels())
smplExp, errExp := expandSeriesIterator(sexp.Iterator())
smplRes, errRes := expandSeriesIterator(sres.Iterator())
testutil.Equals(t, errExp, errRes)
testutil.Equals(t, smplExp, smplRes)
}
}
}
func TestDB_e2e(t *testing.T) {
const (
numDatapoints = 1000
numRanges = 1000
timeInterval = int64(3)
maxTime = int64(2 * 1000)
minTime = int64(200)
)
// Create 8 series with 1000 data-points of different ranges and run queries.
lbls := [][]labels.Label{
{
{"a", "b"},
{"instance", "localhost:9090"},
{"job", "prometheus"},
},
{
{"a", "b"},
{"instance", "127.0.0.1:9090"},
{"job", "prometheus"},
},
{
{"a", "b"},
{"instance", "127.0.0.1:9090"},
{"job", "prom-k8s"},
},
{
{"a", "b"},
{"instance", "localhost:9090"},
{"job", "prom-k8s"},
},
{
{"a", "c"},
{"instance", "localhost:9090"},
{"job", "prometheus"},
},
{
{"a", "c"},
{"instance", "127.0.0.1:9090"},
{"job", "prometheus"},
},
{
{"a", "c"},
{"instance", "127.0.0.1:9090"},
{"job", "prom-k8s"},
},
{
{"a", "c"},
{"instance", "localhost:9090"},
{"job", "prom-k8s"},
},
}
seriesMap := map[string][]sample{}
for _, l := range lbls {
seriesMap[labels.New(l...).String()] = []sample{}
}
db, close := openTestDB(t, nil)
defer close()
defer db.Close()
app := db.Appender()
for _, l := range lbls {
lset := labels.New(l...)
series := []sample{}
ts := rand.Int63n(300)
for i := 0; i < numDatapoints; i++ {
v := rand.Float64()
series = append(series, sample{ts, v})
_, err := app.Add(lset, ts, v)
testutil.Ok(t, err)
ts += rand.Int63n(timeInterval) + 1
}
seriesMap[lset.String()] = series
}
testutil.Ok(t, app.Commit())
// Query each selector on 1000 random time-ranges.
queries := []struct {
ms []labels.Matcher
}{
{
ms: []labels.Matcher{labels.NewEqualMatcher("a", "b")},
},
{
ms: []labels.Matcher{
labels.NewEqualMatcher("a", "b"),
labels.NewEqualMatcher("job", "prom-k8s"),
},
},
{
ms: []labels.Matcher{
labels.NewEqualMatcher("a", "c"),
labels.NewEqualMatcher("instance", "localhost:9090"),
labels.NewEqualMatcher("job", "prometheus"),
},
},
// TODO: Add Regexp Matchers.
}
for _, qry := range queries {
matched := labels.Slice{}
for _, ls := range lbls {
s := labels.Selector(qry.ms)
if s.Matches(ls) {
matched = append(matched, ls)
}
}
sort.Sort(matched)
for i := 0; i < numRanges; i++ {
mint := rand.Int63n(300)
maxt := mint + rand.Int63n(timeInterval*int64(numDatapoints))
expected := map[string][]sample{}
// Build the mockSeriesSet.
for _, m := range matched {
smpls := boundedSamples(seriesMap[m.String()], mint, maxt)
if len(smpls) > 0 {
expected[m.String()] = smpls
}
}
q, err := db.Querier(mint, maxt)
testutil.Ok(t, err)
ss, err := q.Select(qry.ms...)
testutil.Ok(t, err)
result := map[string][]sample{}
for ss.Next() {
x := ss.At()
smpls, err := expandSeriesIterator(x.Iterator())
testutil.Ok(t, err)
if len(smpls) > 0 {
result[x.Labels().String()] = smpls
}
}
testutil.Ok(t, ss.Err())
testutil.Equals(t, expected, result)
q.Close()
}
}
return
}
func TestWALFlushedOnDBClose(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
dirDb := db.Dir()
lbls := labels.Labels{labels.Label{Name: "labelname", Value: "labelvalue"}}
app := db.Appender()
_, err := app.Add(lbls, 0, 1)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
testutil.Ok(t, db.Close())
db, err = Open(dirDb, nil, nil, nil)
testutil.Ok(t, err)
defer db.Close()
q, err := db.Querier(0, 1)
testutil.Ok(t, err)
values, err := q.LabelValues("labelname")
testutil.Ok(t, err)
testutil.Equals(t, values, []string{"labelvalue"})
}
func TestTombstoneClean(t *testing.T) {
numSamples := int64(10)
db, close := openTestDB(t, nil)
defer close()
app := db.Appender()
smpls := make([]float64, numSamples)
for i := int64(0); i < numSamples; i++ {
smpls[i] = rand.Float64()
app.Add(labels.Labels{{"a", "b"}}, i, smpls[i])
}
testutil.Ok(t, app.Commit())
cases := []struct {
intervals Intervals
remaint []int64
}{
{
intervals: Intervals{{1, 3}, {4, 7}},
remaint: []int64{0, 8, 9},
},
}
for _, c := range cases {
// Delete the ranges.
// create snapshot
snap, err := ioutil.TempDir("", "snap")
testutil.Ok(t, err)
defer os.RemoveAll(snap)
testutil.Ok(t, db.Snapshot(snap, true))
testutil.Ok(t, db.Close())
// reopen DB from snapshot
db, err = Open(snap, nil, nil, nil)
testutil.Ok(t, err)
defer db.Close()
for _, r := range c.intervals {
testutil.Ok(t, db.Delete(r.Mint, r.Maxt, labels.NewEqualMatcher("a", "b")))
}
// All of the setup for THIS line.
testutil.Ok(t, db.CleanTombstones())
// Compare the result.
q, err := db.Querier(0, numSamples)
testutil.Ok(t, err)
defer q.Close()
res, err := q.Select(labels.NewEqualMatcher("a", "b"))
testutil.Ok(t, err)
expSamples := make([]sample, 0, len(c.remaint))
for _, ts := range c.remaint {
expSamples = append(expSamples, sample{ts, smpls[ts]})
}
expss := newListSeriesSet([]Series{
newSeries(map[string]string{"a": "b"}, expSamples),
})
if len(expSamples) == 0 {
testutil.Assert(t, res.Next() == false, "")
continue
}
for {
eok, rok := expss.Next(), res.Next()
testutil.Equals(t, eok, rok)
if !eok {
break
}
sexp := expss.At()
sres := res.At()
testutil.Equals(t, sexp.Labels(), sres.Labels())
smplExp, errExp := expandSeriesIterator(sexp.Iterator())
smplRes, errRes := expandSeriesIterator(sres.Iterator())
testutil.Equals(t, errExp, errRes)
testutil.Equals(t, smplExp, smplRes)
}
for _, b := range db.blocks {
testutil.Equals(t, emptyTombstoneReader, b.tombstones)
}
}
}
func TestDB_Retention(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
lbls := labels.Labels{labels.Label{Name: "labelname", Value: "labelvalue"}}
app := db.Appender()
_, err := app.Add(lbls, 0, 1)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
// create snapshot to make it create a block.
// TODO(gouthamve): Add a method to compact headblock.
snap, err := ioutil.TempDir("", "snap")
testutil.Ok(t, err)
defer os.RemoveAll(snap)
testutil.Ok(t, db.Snapshot(snap, true))
testutil.Ok(t, db.Close())
// reopen DB from snapshot
db, err = Open(snap, nil, nil, nil)
testutil.Ok(t, err)
testutil.Equals(t, 1, len(db.blocks))
app = db.Appender()
_, err = app.Add(lbls, 100, 1)
testutil.Ok(t, err)
testutil.Ok(t, app.Commit())
// Snapshot again to create another block.
snap, err = ioutil.TempDir("", "snap")
testutil.Ok(t, err)
defer os.RemoveAll(snap)
testutil.Ok(t, db.Snapshot(snap, true))
testutil.Ok(t, db.Close())
// reopen DB from snapshot
db, err = Open(snap, nil, nil, &Options{
RetentionDuration: 10,
BlockRanges: []int64{50},
})
testutil.Ok(t, err)
defer db.Close()
testutil.Equals(t, 2, len(db.blocks))
// Now call retention.
changes, err := db.retentionCutoff()
testutil.Ok(t, err)
testutil.Assert(t, changes, "there should be changes")
testutil.Equals(t, 1, len(db.blocks))
testutil.Equals(t, int64(100), db.blocks[0].meta.MaxTime) // To verify its the right block.
}
func TestNotMatcherSelectsLabelsUnsetSeries(t *testing.T) {
db, close := openTestDB(t, nil)
defer close()
labelpairs := []labels.Labels{
labels.FromStrings("a", "abcd", "b", "abcde"),
labels.FromStrings("labelname", "labelvalue"),
}
app := db.Appender()
for _, lbls := range labelpairs {
_, err := app.Add(lbls, 0, 1)
testutil.Ok(t, err)
}
testutil.Ok(t, app.Commit())
cases := []struct {
selector labels.Selector
series []labels.Labels
}{{
selector: labels.Selector{
labels.Not(labels.NewEqualMatcher("lname", "lvalue")),
},
series: labelpairs,
}, {
selector: labels.Selector{
labels.NewEqualMatcher("a", "abcd"),
labels.Not(labels.NewEqualMatcher("b", "abcde")),
},
series: []labels.Labels{},
}, {
selector: labels.Selector{
labels.NewEqualMatcher("a", "abcd"),
labels.Not(labels.NewEqualMatcher("b", "abc")),
},
series: []labels.Labels{labelpairs[0]},
}, {
selector: labels.Selector{
labels.Not(labels.NewMustRegexpMatcher("a", "abd.*")),
},
series: labelpairs,
}, {
selector: labels.Selector{
labels.Not(labels.NewMustRegexpMatcher("a", "abc.*")),
},
series: labelpairs[1:],
}, {
selector: labels.Selector{
labels.Not(labels.NewMustRegexpMatcher("c", "abd.*")),
},
series: labelpairs,
}, {
selector: labels.Selector{
labels.Not(labels.NewMustRegexpMatcher("labelname", "labelvalue")),
},
series: labelpairs[:1],
}}
q, err := db.Querier(0, 10)
testutil.Ok(t, err)
defer q.Close()
for _, c := range cases {
ss, err := q.Select(c.selector...)
testutil.Ok(t, err)
lres, err := expandSeriesSet(ss)
testutil.Ok(t, err)
testutil.Equals(t, c.series, lres)
}
}
func expandSeriesSet(ss SeriesSet) ([]labels.Labels, error) {
result := []labels.Labels{}
for ss.Next() {
result = append(result, ss.At().Labels())
}
return result, ss.Err()
}
func TestValidateBlockSequenceDetectsAllOverlaps(t *testing.T) {
var metas []BlockMeta
// Create 10 blocks that does not overlap (0-10, 10-20, ..., 90-100)
for i := 0; i < 10; i++ {
metas = append(metas, BlockMeta{MinTime: int64(i * 10), MaxTime: int64((i + 1) * 10)})
}
overlappedBlocks := ValidateBlockSequence(metas)
testutil.Assert(t, len(overlappedBlocks) == 0, "we found unexpected overlaps")
// Add overlaping blocks.
// o1 overlaps with 10-20.
o1 := BlockMeta{MinTime: 15, MaxTime: 17}
overlappedBlocks = ValidateBlockSequence(append(metas, o1))
expectedOverlaps := [][]BlockMeta{
{metas[1], o1},
}
testutil.Equals(t, expectedOverlaps, overlappedBlocks)
//// o2 overlaps with 20-30 and 30-40.
//o2 := BlockMeta{MinTime: 21, MaxTime: 31}
//
//// o3a and o3b overlaps with 30-40 and each other.
//o3a := BlockMeta{MinTime: 33, MaxTime: 39}
//o3b := BlockMeta{MinTime: 34, MaxTime: 36}
//
//// o4 is 1:1 overlap with 50-60
//o4 := BlockMeta{MinTime: 50, MaxTime: 60}
//
//// o5 overlaps with 50-60, 60-70 and 70,80
//o5 := BlockMeta{MinTime: 60, MaxTime: 80}
//
//expectedOverlaps := [][]block.Meta{
// {metas[1], o1},
// {metas[2], o2},
// {metas[3], o2},
// {metas[3], o3, o3b},
//}
}