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chunks: bring back lead/trail reuse, truncate incomplete sample

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This commit is contained in:
Fabian Reinartz 2016-11-30 23:01:01 +01:00
parent 8c48dc2ca5
commit 0b6d621471
2 changed files with 21 additions and 10 deletions
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14
chunks/chunk_test.go
View file

@ -20,7 +20,7 @@ func TestChunk(t *testing.T) {
EncXOR: func(sz int) Chunk { return NewXORChunk(sz) },
} {
t.Run(fmt.Sprintf("%s", enc), func(t *testing.T) {
for range make([]struct{}, 3000) {
for range make([]struct{}, 1) {
c := nc(rand.Intn(1024))
if err := testChunk(c); err != nil {
t.Fatal(err)
@ -42,10 +42,14 @@ func testChunk(c Chunk) error {
v = 1243535.123
)
i := 0
for i < 3 {
for {
ts += int64(rand.Intn(10000) + 1)
v = rand.Float64()
// v += float64(100)
// v = rand.Float64()
if i%2 == 0 {
v += float64(rand.Intn(1000000))
} else {
v -= float64(rand.Intn(1000000))
}
// Start with a new appender every 10th sample. This emulates starting
// appending to a partially filled chunk.
@ -93,7 +97,7 @@ func benchmarkIterator(b *testing.B, newChunk func(int) Chunk) {
// t += int64(rand.Intn(10000) + 1)
t += int64(1000)
// v = rand.Float64()
v += float64(100)
// v += float64(100)
exp = append(exp, pair{t: t, v: v})
}

17
chunks/xor.go
View file

@ -48,7 +48,7 @@ func (c *XORChunk) Appender() (Appender, error) {
return nil, err
}
return &xorAppender{
a := &xorAppender{
c: c,
b: c.b,
t: it.t,
@ -56,7 +56,11 @@ func (c *XORChunk) Appender() (Appender, error) {
tDelta: it.tDelta,
leading: it.leading,
trailing: it.trailing,
}, nil
}
if c.num == 0 {
a.leading = 0xff
}
return a, nil
}
func (c *XORChunk) iterator() *xorIterator {
@ -88,6 +92,7 @@ type xorAppender struct {
func (a *xorAppender) Append(t int64, v float64) error {
var tDelta uint64
l := len(a.b.bytes())
if a.c.num == 0 {
buf := make([]byte, binary.MaxVarintLen64)
@ -133,6 +138,9 @@ func (a *xorAppender) Append(t int64, v float64) error {
}
if len(a.b.bytes()) > a.c.sz {
// If the appended data exceeded the size limit, we truncate
// the underlying data slice back to the length we started with.
a.b.stream = a.b.stream[:l]
return ErrChunkFull
}
@ -156,13 +164,12 @@ func (a *xorAppender) writeVDelta(v float64) {
leading := uint8(bits.Clz(vDelta))
trailing := uint8(bits.Ctz(vDelta))
// clamp number of leading zeros to avoid overflow when encoding
// Clamp number of leading zeros to avoid overflow when encoding.
if leading >= 32 {
leading = 31
}
// TODO(dgryski): check if it's 'cheaper' to reset the leading/trailing bits instead
if a.leading != ^uint8(0) && leading >= a.leading && trailing >= a.trailing {
if a.leading != 0xff && leading >= a.leading && trailing >= a.trailing {
a.b.writeBit(zero)
a.b.writeBits(vDelta>>a.trailing, 64-int(a.leading)-int(a.trailing))
} else {