Revert "Add comments and test for 64-bit field alignment (#418)"

This reverts commit 91091b4.

api/core/number_test.go

@@ -67,14 +67,12 @@ func TestNumber(t *testing.T) {
 	cmpsForPos := [3]int{1, 1, 0}
 
 	type testcase struct {
-		// n needs to be aligned for 64-bit atomic operations.
-		n Number
-		// nums needs to be aligned for 64-bit atomic operations.
-		nums [3]Number
+		n    Number
 		kind NumberKind
 		pos  bool
 		zero bool
 		neg  bool
+		nums [3]Number
 		cmps [3]int
 	}
 	testcases := []testcase{

api/metric/api.go

@@ -85,9 +85,8 @@ type MeasureOptionApplier interface {
 // values. Instances of this type should be created by instruments
 // (e.g., Int64Counter.Measurement()).
 type Measurement struct {
-	// number needs to be aligned for 64-bit atomic operations.
-	number     core.Number
 	instrument InstrumentImpl
+	number     core.Number
 }
 
 // Instrument returns the instrument that created this measurement.

internal/metric/mock.go

@@ -41,10 +41,9 @@ type (
 	}
 
 	Batch struct {
-		// Measurement needs to be aligned for 64-bit atomic operations.
-		Measurements []Measurement
 		Ctx          context.Context
 		LabelSet     *LabelSet
+		Measurements []Measurement
 	}
 
 	MeterProvider struct {
@@ -59,9 +58,8 @@ type (
 	Kind int8
 
 	Measurement struct {
-		// Number needs to be aligned for 64-bit atomic operations.
-		Number     core.Number
 		Instrument *Instrument
+		Number     core.Number
 	}
 )
 

internal/trace/mock_tracer.go

@@ -28,14 +28,12 @@ import (
 // It only supports ChildOf option. SpanId is atomically increased every time a
 // new span is created.
 type MockTracer struct {
+	// Sampled specifies if the new span should be sampled or not.
+	Sampled bool
+
 	// StartSpanID is used to initialize spanId. It is incremented by one
 	// every time a new span is created.
-	//
-	// StartSpanID has to be aligned for 64-bit atomic operations.
 	StartSpanID *uint64
-
-	// Sampled specifies if the new span should be sampled or not.
-	Sampled bool
 }
 
 var _ apitrace.Tracer = (*MockTracer)(nil)

sdk/metric/aggregator/array/array.go

@@ -28,11 +28,10 @@ import (
 
 type (
 	Aggregator struct {
-		// ckptSum needs to be aligned for 64-bit atomic operations.
-		ckptSum    core.Number
 		lock       sync.Mutex
 		current    points
 		checkpoint points
+		ckptSum    core.Number
 	}
 
 	points []core.Number

sdk/metric/aggregator/array/array_test.go

@@ -18,34 +18,16 @@ import (
 	"context"
 	"fmt"
 	"math"
-	"os"
 	"testing"
-	"unsafe"
 
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/api/core"
-	ottest "go.opentelemetry.io/otel/internal/testing"
 	export "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
 	"go.opentelemetry.io/otel/sdk/metric/aggregator/test"
 )
 
-// Ensure struct alignment prior to running tests.
-func TestMain(m *testing.M) {
-	fields := []ottest.FieldOffset{
-		{
-			Name:   "Aggregator.ckptSum",
-			Offset: unsafe.Offsetof(Aggregator{}.ckptSum),
-		},
-	}
-	if !ottest.Aligned8Byte(fields, os.Stderr) {
-		os.Exit(1)
-	}
-
-	os.Exit(m.Run())
-}
-
 type updateTest struct {
 	count    int
 	absolute bool

sdk/metric/aggregator/counter/counter.go

@@ -25,11 +25,9 @@ import (
 // Aggregator aggregates counter events.
 type Aggregator struct {
 	// current holds current increments to this counter record
-	// current needs to be aligned for 64-bit atomic operations.
 	current core.Number
 
 	// checkpoint is a temporary used during Checkpoint()
-	// checkpoint needs to be aligned for 64-bit atomic operations.
 	checkpoint core.Number
 }
 

sdk/metric/aggregator/counter/counter_test.go

@@ -16,39 +16,17 @@ package counter
 
 import (
 	"context"
-	"os"
 	"testing"
-	"unsafe"
 
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/api/core"
-	ottest "go.opentelemetry.io/otel/internal/testing"
 	export "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/metric/aggregator/test"
 )
 
 const count = 100
 
-// Ensure struct alignment prior to running tests.
-func TestMain(m *testing.M) {
-	fields := []ottest.FieldOffset{
-		{
-			Name:   "Aggregator.current",
-			Offset: unsafe.Offsetof(Aggregator{}.current),
-		},
-		{
-			Name:   "Aggregator.checkpoint",
-			Offset: unsafe.Offsetof(Aggregator{}.checkpoint),
-		},
-	}
-	if !ottest.Aligned8Byte(fields, os.Stderr) {
-		os.Exit(1)
-	}
-
-	os.Exit(m.Run())
-}
-
 func TestCounterMonotonic(t *testing.T) {
 	ctx := context.Background()
 

sdk/metric/aggregator/gauge/gauge.go

@@ -45,8 +45,6 @@ type (
 	// a sequence number to determine the winner of a race.
 	gaugeData struct {
 		// value is the int64- or float64-encoded Set() data
-		//
-		// value needs to be aligned for 64-bit atomic operations.
 		value core.Number
 
 		// timestamp indicates when this record was submitted.

sdk/metric/aggregator/gauge/gauge_test.go

@@ -17,14 +17,11 @@ package gauge
 import (
 	"context"
 	"math/rand"
-	"os"
 	"testing"
-	"unsafe"
 
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/api/core"
-	ottest "go.opentelemetry.io/otel/internal/testing"
 	export "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
 	"go.opentelemetry.io/otel/sdk/metric/aggregator/test"
@@ -34,21 +31,6 @@ const count = 100
 
 var _ export.Aggregator = &Aggregator{}
 
-// Ensure struct alignment prior to running tests.
-func TestMain(m *testing.M) {
-	fields := []ottest.FieldOffset{
-		{
-			Name:   "gaugeData.value",
-			Offset: unsafe.Offsetof(gaugeData{}.value),
-		},
-	}
-	if !ottest.Aligned8Byte(fields, os.Stderr) {
-		os.Exit(1)
-	}
-
-	os.Exit(m.Run())
-}
-
 func TestGaugeNonMonotonic(t *testing.T) {
 	ctx := context.Background()
 

sdk/metric/aggregator/minmaxsumcount/mmsc.go

@@ -26,15 +26,12 @@ type (
 	// Aggregator aggregates measure events, keeping only the max,
 	// sum, and count.
 	Aggregator struct {
-		// current has to be aligned for 64-bit atomic operations.
-		current state
-		// checkpoint has to be aligned for 64-bit atomic operations.
+		current    state
 		checkpoint state
 		kind       core.NumberKind
 	}
 
 	state struct {
-		// all fields have to be aligned for 64-bit atomic operations.
 		count core.Number
 		sum   core.Number
 		min   core.Number