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[BUGFIX] labels: don't modify original labels in DropMetricName (#13845)

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Restrict the capacity of first argument to `append()` to force an allocation.
This is for the slice implementation only.

Signed-off-by: Domantas Jadenkus <djadenkus@gmail.com>
This commit is contained in:
Domantas 2024-03-27 12:35:17 +02:00 committed by GitHub
parent 25a8d57671
commit 435f330d0b
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GPG key ID: B5690EEEBB952194
3 changed files with 26 additions and 2 deletions
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4
model/labels/labels.go
View file

@ -349,7 +349,9 @@ func (ls Labels) DropMetricName() Labels {
if i == 0 { // Make common case fast with no allocations.
return ls[1:]
}
return append(ls[:i], ls[i+1:]...)
// Avoid modifying original Labels - use [:i:i] so that left slice would not
// have any spare capacity and append would have to allocate a new slice for the result.
return append(ls[:i:i], ls[i+1:]...)
}
}
return ls

6
model/labels/labels_test.go
View file

@ -457,7 +457,11 @@ func TestLabels_Get(t *testing.T) {
func TestLabels_DropMetricName(t *testing.T) {
require.True(t, Equal(FromStrings("aaa", "111", "bbb", "222"), FromStrings("aaa", "111", "bbb", "222").DropMetricName()))
require.True(t, Equal(FromStrings("aaa", "111"), FromStrings(MetricName, "myname", "aaa", "111").DropMetricName()))
require.True(t, Equal(FromStrings("__aaa__", "111", "bbb", "222"), FromStrings("__aaa__", "111", MetricName, "myname", "bbb", "222").DropMetricName()))
original := FromStrings("__aaa__", "111", MetricName, "myname", "bbb", "222")
check := FromStrings("__aaa__", "111", MetricName, "myname", "bbb", "222")
require.True(t, Equal(FromStrings("__aaa__", "111", "bbb", "222"), check.DropMetricName()))
require.True(t, Equal(original, check))
}
// BenchmarkLabels_Get was written to check whether a binary search can improve the performance vs the linear search implementation

18
promql/engine_test.go
View file

@ -3212,6 +3212,24 @@ func TestRangeQuery(t *testing.T) {
End: time.Unix(120, 0),
Interval: 1 * time.Minute,
},
{
Name: "drop-metric-name",
Load: `load 30s
requests{job="1", __address__="bar"} 100`,
Query: `requests * 2`,
Result: Matrix{
Series{
Floats: []FPoint{{F: 200, T: 0}, {F: 200, T: 60000}, {F: 200, T: 120000}},
Metric: labels.FromStrings(
"__address__", "bar",
"job", "1",
),
},
},
Start: time.Unix(0, 0),
End: time.Unix(120, 0),
Interval: 1 * time.Minute,
},
}
for _, c := range cases {
t.Run(c.Name, func(t *testing.T) {