version: commit hash crc of first stat should be real

After calculating the crc of the commit hash, we should use real value instead of 0.

Also started using info.CommitHash, as it's the same (or better, it may include vcs version, if build tag is missing), and easier to test...

Change-Id: I9621732cce6bf9f2c7deebca3e55681af761dacc

Author: elek

version/stats.go

@@ -37,11 +37,12 @@ func (info *Info) Stats(cb func(key monkit.SeriesKey, field string, val float64)
 	crc := atomic.LoadUint32(&info.commitHashCRC)
 	if crc == 0 {
 		c := crc32.NewIEEE()
-		_, err := c.Write([]byte(buildCommitHash))
+		_, err := c.Write([]byte(info.CommitHash))
 		if err != nil {
 			panic(err)
 		}
-		atomic.StoreUint32(&info.commitHashCRC, c.Sum32())
+		crc = c.Sum32()
+		atomic.StoreUint32(&info.commitHashCRC, crc)
 	}
 	cb(key, "commit", float64(crc))
 	cb(key, "major", float64(info.Version.Major))

version/stats_test.go

@@ -5,8 +5,31 @@ package version
 
 import (
 	"testing"
+
+	"github.com/spacemonkeygo/monkit/v3"
+	"github.com/stretchr/testify/require"
 )
 
 func TestOsVersion(t *testing.T) {
 	t.Log(osversion())
 }
+
+func TestCommitHashCRC(t *testing.T) {
+	info := Info{
+		CommitHash: "0e7695f391df6c2ea03d2dec02b9059ccaffb9c9",
+	}
+
+	getCommitHash := func() (ret float64) {
+		info.Stats(func(key monkit.SeriesKey, field string, val float64) {
+			if key.Measurement == "version_info" && field == "commit" {
+				ret = val
+			}
+		})
+		return ret
+	}
+
+	// first time the value is calculated, second time cached value is used.
+	// Let's test both.
+	require.Equal(t, float64(868966439), getCommitHash())
+	require.Equal(t, float64(868966439), getCommitHash())
+}