Implements review commentary

Specifically @beorn7 pointed out that the previous implementation had
some shortcomings around large numbers. I've changed the code to match
the suggestion in review, as well as added a few test cases.
This commit is contained in:
Stephen McQuay (smcquay) 2017-12-15 11:00:37 -08:00
parent ae6939214c
commit 35559538c7
No known key found for this signature in database
GPG Key ID: 4E4B72F479BA3CE5
2 changed files with 87 additions and 3 deletions

View File

@ -126,3 +126,87 @@ func expectPanic(t *testing.T, op func(), errorMsg string) {
op() op()
} }
func TestCounterAddInf(t *testing.T) {
counter := NewCounter(CounterOpts{
Name: "test",
Help: "test help",
}).(*counter)
counter.Inc()
if expected, got := 0.0, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
if expected, got := int64(1), counter.valInt; expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
counter.Add(math.Inf(1))
if expected, got := math.Inf(1), math.Float64frombits(counter.valBits); expected != got {
t.Errorf("valBits expected %f, got %f.", expected, got)
}
if expected, got := int64(1), counter.valInt; expected != got {
t.Errorf("valInts expected %d, got %d.", expected, got)
}
counter.Inc()
if expected, got := math.Inf(1), math.Float64frombits(counter.valBits); expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
if expected, got := int64(2), counter.valInt; expected != got {
t.Errorf("Expected %d, got %d.", expected, got)
}
m := &dto.Metric{}
counter.Write(m)
if expected, got := `counter:<value:inf > `, m.String(); expected != got {
t.Errorf("expected %q, got %q", expected, got)
}
}
func TestCounterAddLarge(t *testing.T) {
counter := NewCounter(CounterOpts{
Name: "test",
Help: "test help",
}).(*counter)
// large overflows the underlying type and should therefore be stored in valBits
large := float64(math.MaxInt64 + 1)
counter.Add(large)
if expected, got := large, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("valBits expected %f, got %f.", expected, got)
}
if expected, got := int64(0), counter.valInt; expected != got {
t.Errorf("valInts expected %d, got %d.", expected, got)
}
m := &dto.Metric{}
counter.Write(m)
if expected, got := fmt.Sprintf("counter:<value:%0.15e > ", large), m.String(); expected != got {
t.Errorf("expected %q, got %q", expected, got)
}
}
func TestCounterAddSmall(t *testing.T) {
counter := NewCounter(CounterOpts{
Name: "test",
Help: "test help",
}).(*counter)
small := 0.000000000001
counter.Add(small)
if expected, got := small, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("valBits expected %f, got %f.", expected, got)
}
if expected, got := int64(0), counter.valInt; expected != got {
t.Errorf("valInts expected %d, got %d.", expected, got)
}
m := &dto.Metric{}
counter.Write(m)
if expected, got := fmt.Sprintf("counter:<value:%0.0e > ", small), m.String(); expected != got {
t.Errorf("expected %q, got %q", expected, got)
}
}

View File

@ -45,7 +45,6 @@ type value struct {
// to go first in the struct to guarantee alignment for atomic // to go first in the struct to guarantee alignment for atomic
// operations. http://golang.org/pkg/sync/atomic/#pkg-note-BUG // operations. http://golang.org/pkg/sync/atomic/#pkg-note-BUG
valBits uint64 valBits uint64
// valInt is used to store values that are exact integers // valInt is used to store values that are exact integers
valInt int64 valInt int64
@ -99,8 +98,9 @@ func (v *value) Dec() {
} }
func (v *value) Add(val float64) { func (v *value) Add(val float64) {
if math.Trunc(val) == val { ival := int64(val)
atomic.AddInt64(&v.valInt, int64(val)) if float64(ival) == val {
v.add(ival)
return return
} }