unexport StatsEntries, lock on gatherMetrics

Signed-off-by: Alex Pana <8968914+acpana@users.noreply.github.com>

constraint/pkg/client/client.go

@@ -588,8 +588,7 @@ func (c *Client) review(ctx context.Context, target string, constraints []*unstr
 
 	var statsEntries []*instrumentation.StatsEntry
 	if localDriver, ok := c.driver.(*local.Driver); ok {
-		statsEntries = make([]*instrumentation.StatsEntry, len(localDriver.StatsEntries))
-		copy(statsEntries, localDriver.StatsEntries)
+		statsEntries = localDriver.StatsEntries()
 	}
 
 	return &types.Response{

constraint/pkg/client/drivers/local/args.go

@@ -160,7 +160,7 @@ func Externs(externs ...string) Arg {
 func GatherMetrics() Arg {
 	return func(driver *Driver) error {
 		driver.gatherMetrics = true
-		driver.StatsEntries = make([]*instrumentation.StatsEntry, 0)
+		driver.statsEntries = make([]*instrumentation.StatsEntry, 0)
 
 		return nil
 	}

constraint/pkg/client/drivers/local/driver.go

@@ -77,9 +77,24 @@ type Driver struct {
 	// gatherMetrics controls whether the driver attempts to gather any metrics around its API calls
 	gatherMetrics bool
 
-	// StatsEntries returns the current statistics observed since the last API call. At present
-	// StatsEntries are only gathered on the Query() API.
-	StatsEntries []*instrumentation.StatsEntry
+	// statsEntries returns the current statistics observed since the last API call. At present
+	// statsEntries are only gathered on the Query() API.
+	statsEntries []*instrumentation.StatsEntry
+}
+
+// StatsEntries returns any stats associated with the driver API if GatherMetrics
+// driver arg was passed in. The only current endpoinut supported is Query().
+func (d *Driver) StatsEntries() []*instrumentation.StatsEntry {
+	if d.gatherMetrics {
+		d.mtx.Lock()
+		defer d.mtx.Unlock()
+
+		cpy := make([]*instrumentation.StatsEntry, len(d.statsEntries))
+		copy(cpy, d.statsEntries)
+		return cpy
+	}
+
+	return nil
 }
 
 // AddTemplate adds templ to Driver. Normalizes modules into usable forms for
@@ -225,8 +240,16 @@ func (d *Driver) eval(ctx context.Context, compiler *ast.Compiler, target string
 }
 
 func (d *Driver) Query(ctx context.Context, target string, constraints []*unstructured.Unstructured, review interface{}, opts ...drivers.QueryOpt) ([]*types.Result, *string, error) {
-	// reset stats entries every time
-	d.StatsEntries = make([]*instrumentation.StatsEntry, 0)
+	if d.gatherMetrics {
+		d.mtx.Lock()
+		defer d.mtx.Unlock()
+
+		// reset stats entries every time
+		d.statsEntries = make([]*instrumentation.StatsEntry, 0)
+	} else {
+		d.mtx.RLock()
+		defer d.mtx.RUnlock()
+	}
 
 	if len(constraints) == 0 {
 		return nil, nil, nil
@@ -247,9 +270,6 @@ func (d *Driver) Query(ctx context.Context, target string, constraints []*unstru
 		return nil, nil, err
 	}
 
-	d.mtx.RLock()
-	defer d.mtx.RUnlock()
-
 	for kind, kindConstraints := range constraintsByKind {
 		evalStartTime := time.Now()
 		compiler := d.compilers.getCompiler(target, kind)
@@ -322,7 +342,7 @@ func (d *Driver) Query(ctx context.Context, target string, constraints []*unstru
 					},
 				}
 
-				d.StatsEntries = append(d.StatsEntries, statsEntry)
+				d.statsEntries = append(d.statsEntries, statsEntry)
 			}
 		}
 	}

constraint/pkg/client/drivers/local/driver_unit_test.go

@@ -223,7 +223,7 @@ func TestDriver_Query_StatsEntries(t *testing.T) {
 
 	// then expext two stats entries that correspond to the
 	// two constraints that were passed in to the Query call
-	ses := d.StatsEntries
+	ses := d.statsEntries
 	if len(ses) != 2 {
 		t.Fatalf("got %d errors on normal query; want 2", len(ses))
 	}
@@ -283,7 +283,7 @@ func TestDriver_Query_StatsEntries(t *testing.T) {
 
 	// then expect a new StatsEntry entirely, with no
 	// leaks of the previous data in it.
-	ses2 := d.StatsEntries
+	ses2 := d.statsEntries
 	if reflect.DeepEqual(ses, ses2) {
 		t.Fatalf("got the same slice on a new Query call")
 	}
@@ -340,7 +340,7 @@ func TestDriver_Query_StatsEntries_nonViolating(t *testing.T) {
 	}
 
 	// then we want to see a stats entry for the non violating constraint
-	ses := d.StatsEntries
+	ses := d.statsEntries
 	if len(ses) != 1 {
 		t.Fatalf("got %d errors on normal query; want 1", len(ses))
 	}