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Merge pull request #6585 from prometheus/fix-symbols-lookup

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tsdb: Fixed Symbol Lookup edge case; Added tests.
This commit is contained in:
Bartlomiej Plotka 2020-01-10 11:44:23 +00:00 committed by GitHub
parent ab8748d0e0 59ea320d96
commit 1e64d757f7
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 51 additions and 6 deletions
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9
tsdb/index/index.go
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@ -1242,17 +1242,13 @@ func NewSymbols(bs ByteSlice, version int, off int) (*Symbols, error) {
version: version,
off: off,
}
if off == 0 {
// Only happens in some tests.
return nil, nil
}
d := encoding.NewDecbufAt(bs, off, castagnoliTable)
var (
origLen = d.Len()
cnt = d.Be32int()
basePos = off + 4
)
s.offsets = make([]int, 0, cnt/symbolFactor)
s.offsets = make([]int, 0, 1+cnt/symbolFactor)
for d.Err() == nil && s.seen < cnt {
if s.seen%symbolFactor == 0 {
s.offsets = append(s.offsets, basePos+origLen-d.Len())
@ -1270,8 +1266,9 @@ func (s Symbols) Lookup(o uint32) (string, error) {
d := encoding.Decbuf{
B: s.bs.Range(0, s.bs.Len()),
}
if s.version == FormatV2 {
if int(o) > s.seen {
if int(o) >= s.seen {
return "", errors.Errorf("unknown symbol offset %d", o)
}
d.Skip(s.offsets[int(o/symbolFactor)])

48
tsdb/index/index_test.go
View file

@ -16,6 +16,7 @@ package index
import (
"context"
"fmt"
"hash/crc32"
"io/ioutil"
"math/rand"
"os"
@ -505,3 +506,50 @@ func TestNewFileReaderErrorNoOpenFiles(t *testing.T) {
// dir.Close will fail on Win if idxName fd is not closed on error path.
dir.Close()
}
func TestSymbols(t *testing.T) {
buf := encoding.Encbuf{}
// Add prefix to the buffer to simulate symbols as part of larger buffer.
buf.PutUvarintStr("something")
symbolsStart := buf.Len()
buf.PutBE32int(204) // Length of symbols table.
buf.PutBE32int(100) // Number of symbols.
for i := 0; i < 100; i++ {
// i represents index in unicode characters table.
buf.PutUvarintStr(string(i)) // Symbol.
}
checksum := crc32.Checksum(buf.Get()[symbolsStart+4:], castagnoliTable)
buf.PutBE32(checksum) // Check sum at the end.
s, err := NewSymbols(realByteSlice(buf.Get()), FormatV2, symbolsStart)
testutil.Ok(t, err)
// We store only 4 offsets to symbols.
testutil.Equals(t, 32, s.Size())
for i := 99; i >= 0; i-- {
s, err := s.Lookup(uint32(i))
testutil.Ok(t, err)
testutil.Equals(t, string(i), s)
}
_, err = s.Lookup(100)
testutil.NotOk(t, err)
for i := 99; i >= 0; i-- {
r, err := s.ReverseLookup(string(i))
testutil.Ok(t, err)
testutil.Equals(t, uint32(i), r)
}
_, err = s.ReverseLookup(string(100))
testutil.NotOk(t, err)
iter := s.Iter()
i := 0
for iter.Next() {
testutil.Equals(t, string(i), iter.At())
i++
}
testutil.Ok(t, iter.Err())
}