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Merge pull request #13208 from linasm/panic-free-float-histogram-add-sub 

FloatHistogram.Add/Sub: handle any schema change
This commit is contained in:
Björn Rabenstein 2023-12-07 20:12:21 +01:00 committed by GitHub
parent de1ec731c7 bd895baefc
commit 85078b968f
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 80 additions and 29 deletions
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45
model/histogram/float_histogram.go
View File

@ -231,11 +231,8 @@ func (h *FloatHistogram) Div(scalar float64) *FloatHistogram {
// resulting histogram might have buckets with a population of zero or directly
// adjacent spans (offset=0). To normalize those, call the Compact method.
//
// The method reconciles differences in the zero threshold and in the schema,
// but the schema of the other histogram must be ≥ the schema of the receiving
// histogram (i.e. must have an equal or higher resolution). This means that the
// schema of the receiving histogram won't change. Its zero threshold, however,
// will change if needed. The other histogram will not be modified in any case.
// The method reconciles differences in the zero threshold and in the schema, and
// changes them if needed. The other histogram will not be modified in any case.
//
// This method returns a pointer to the receiving histogram for convenience.
func (h *FloatHistogram) Add(other *FloatHistogram) *FloatHistogram {
@ -269,21 +266,30 @@ func (h *FloatHistogram) Add(other *FloatHistogram) *FloatHistogram {
h.Sum += other.Sum
var (
hPositiveSpans = h.PositiveSpans
hPositiveBuckets = h.PositiveBuckets
hNegativeSpans = h.NegativeSpans
hNegativeBuckets = h.NegativeBuckets
otherPositiveSpans = other.PositiveSpans
otherPositiveBuckets = other.PositiveBuckets
otherNegativeSpans = other.NegativeSpans
otherNegativeBuckets = other.NegativeBuckets
)
if other.Schema < h.Schema {
panic(fmt.Errorf("cannot add histogram with schema %d to %d", other.Schema, h.Schema))
} else if other.Schema > h.Schema {
switch {
case other.Schema < h.Schema:
hPositiveSpans, hPositiveBuckets = reduceResolution(hPositiveSpans, hPositiveBuckets, h.Schema, other.Schema, false, true)
hNegativeSpans, hNegativeBuckets = reduceResolution(hNegativeSpans, hNegativeBuckets, h.Schema, other.Schema, false, true)
h.Schema = other.Schema
case other.Schema > h.Schema:
otherPositiveSpans, otherPositiveBuckets = reduceResolution(otherPositiveSpans, otherPositiveBuckets, other.Schema, h.Schema, false, false)
otherNegativeSpans, otherNegativeBuckets = reduceResolution(otherNegativeSpans, otherNegativeBuckets, other.Schema, h.Schema, false, false)
}
h.PositiveSpans, h.PositiveBuckets = addBuckets(h.Schema, h.ZeroThreshold, false, h.PositiveSpans, h.PositiveBuckets, otherPositiveSpans, otherPositiveBuckets)
h.NegativeSpans, h.NegativeBuckets = addBuckets(h.Schema, h.ZeroThreshold, false, h.NegativeSpans, h.NegativeBuckets, otherNegativeSpans, otherNegativeBuckets)
h.PositiveSpans, h.PositiveBuckets = addBuckets(h.Schema, h.ZeroThreshold, false, hPositiveSpans, hPositiveBuckets, otherPositiveSpans, otherPositiveBuckets)
h.NegativeSpans, h.NegativeBuckets = addBuckets(h.Schema, h.ZeroThreshold, false, hNegativeSpans, hNegativeBuckets, otherNegativeSpans, otherNegativeBuckets)
return h
}
@ -296,21 +302,30 @@ func (h *FloatHistogram) Sub(other *FloatHistogram) *FloatHistogram {
h.Sum -= other.Sum
var (
hPositiveSpans = h.PositiveSpans
hPositiveBuckets = h.PositiveBuckets
hNegativeSpans = h.NegativeSpans
hNegativeBuckets = h.NegativeBuckets
otherPositiveSpans = other.PositiveSpans
otherPositiveBuckets = other.PositiveBuckets
otherNegativeSpans = other.NegativeSpans
otherNegativeBuckets = other.NegativeBuckets
)
if other.Schema < h.Schema {
panic(fmt.Errorf("cannot subtract histigram with schema %d to %d", other.Schema, h.Schema))
} else if other.Schema > h.Schema {
switch {
case other.Schema < h.Schema:
hPositiveSpans, hPositiveBuckets = reduceResolution(hPositiveSpans, hPositiveBuckets, h.Schema, other.Schema, false, true)
hNegativeSpans, hNegativeBuckets = reduceResolution(hNegativeSpans, hNegativeBuckets, h.Schema, other.Schema, false, true)
h.Schema = other.Schema
case other.Schema > h.Schema:
otherPositiveSpans, otherPositiveBuckets = reduceResolution(otherPositiveSpans, otherPositiveBuckets, other.Schema, h.Schema, false, false)
otherNegativeSpans, otherNegativeBuckets = reduceResolution(otherNegativeSpans, otherNegativeBuckets, other.Schema, h.Schema, false, false)
}
h.PositiveSpans, h.PositiveBuckets = addBuckets(h.Schema, h.ZeroThreshold, true, h.PositiveSpans, h.PositiveBuckets, otherPositiveSpans, otherPositiveBuckets)
h.NegativeSpans, h.NegativeBuckets = addBuckets(h.Schema, h.ZeroThreshold, true, h.NegativeSpans, h.NegativeBuckets, otherNegativeSpans, otherNegativeBuckets)
h.PositiveSpans, h.PositiveBuckets = addBuckets(h.Schema, h.ZeroThreshold, true, hPositiveSpans, hPositiveBuckets, otherPositiveSpans, otherPositiveBuckets)
h.NegativeSpans, h.NegativeBuckets = addBuckets(h.Schema, h.ZeroThreshold, true, hNegativeSpans, hNegativeBuckets, otherNegativeSpans, otherNegativeBuckets)
return h
}

64
model/histogram/float_histogram_test.go
View File

@ -1242,7 +1242,7 @@ func TestFloatHistogramAdd(t *testing.T) {
Sum: 1.234,
PositiveSpans: []Span{{0, 2}, {3, 3}},
PositiveBuckets: []float64{5, 4, 2, 3, 6},
NegativeSpans: []Span{{-9, 2}, {3, 2}},
NegativeSpans: []Span{{-6, 2}, {1, 2}},
NegativeBuckets: []float64{1, 1, 4, 4},
},
&FloatHistogram{
@ -1262,7 +1262,7 @@ func TestFloatHistogramAdd(t *testing.T) {
Sum: 3.579,
PositiveSpans: []Span{{-2, 2}, {0, 5}, {0, 3}},
PositiveBuckets: []float64{1, 0, 5, 4, 3, 4, 7, 2, 3, 6},
NegativeSpans: []Span{{-9, 2}, {3, 2}, {5, 2}, {3, 2}},
NegativeSpans: []Span{{-6, 2}, {1, 2}, {4, 2}, {3, 2}},
NegativeBuckets: []float64{1, 1, 4, 4, 3, 1, 5, 6},
},
},
@ -1573,16 +1573,33 @@ func TestFloatHistogramAdd(t *testing.T) {
for _, c := range cases {
t.Run(c.name, func(t *testing.T) {
in2Copy := c.in2.Copy()
require.Equal(t, c.expected, c.in1.Add(c.in2))
// Has it also happened in-place?
require.Equal(t, c.expected, c.in1)
// Check that the argument was not mutated.
require.Equal(t, in2Copy, c.in2)
testHistogramAdd(t, c.in1, c.in2, c.expected)
testHistogramAdd(t, c.in2, c.in1, c.expected)
})
}
}
func testHistogramAdd(t *testing.T, a, b, expected *FloatHistogram) {
var (
aCopy = a.Copy()
bCopy = b.Copy()
expectedCopy = expected.Copy()
)
res := aCopy.Add(bCopy)
res.Compact(0)
expectedCopy.Compact(0)
require.Equal(t, expectedCopy, res)
// Has it also happened in-place?
require.Equal(t, expectedCopy, aCopy)
// Check that the argument was not mutated.
require.Equal(t, b, bCopy)
}
func TestFloatHistogramSub(t *testing.T) {
// This has fewer test cases than TestFloatHistogramAdd because Add and
// Sub share most of the trickier code.
@ -1662,16 +1679,35 @@ func TestFloatHistogramSub(t *testing.T) {
for _, c := range cases {
t.Run(c.name, func(t *testing.T) {
in2Copy := c.in2.Copy()
require.Equal(t, c.expected, c.in1.Sub(c.in2))
// Has it also happened in-place?
require.Equal(t, c.expected, c.in1)
// Check that the argument was not mutated.
require.Equal(t, in2Copy, c.in2)
testFloatHistogramSub(t, c.in1, c.in2, c.expected)
expectedNegative := c.expected.Copy().Mul(-1)
testFloatHistogramSub(t, c.in2, c.in1, expectedNegative)
})
}
}
func testFloatHistogramSub(t *testing.T, a, b, expected *FloatHistogram) {
var (
aCopy = a.Copy()
bCopy = b.Copy()
expectedCopy = expected.Copy()
)
res := aCopy.Sub(bCopy)
res.Compact(0)
expectedCopy.Compact(0)
require.Equal(t, expectedCopy, res)
// Has it also happened in-place?
require.Equal(t, expectedCopy, aCopy)
// Check that the argument was not mutated.
require.Equal(t, b, bCopy)
}
func TestFloatHistogramCopyToSchema(t *testing.T) {
cases := []struct {
name string