Cleanup usage of TimestampUnixNanos and its API (#2549)

Updates #2488

Important Changes:

* Rename pdata.TimestampUnixNanos to pdata.Timestamp
* Remove pdata.TimestampUnixNanos and helpers, move them of the pdata.Timestamp type.
* Fix bug around IsZero, this function should return true if the time is January 1, year 1, 00:00:00 UTC not epoch.

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

Author: bogdandrutu

cmd/pdatagen/internal/base_fields.go

@@ -240,7 +240,7 @@ func (pf *primitiveField) generateCopyToValue(sb *strings.Builder) {
 
 var _ baseField = (*primitiveField)(nil)
 
-// Types that has defined a custom type (e.g. "type TimestampUnixNano uint64")
+// Types that has defined a custom type (e.g. "type Timestamp uint64")
 type primitiveTypedField struct {
 	fieldName       string
 	originFieldName string

cmd/pdatagen/internal/common_structs.go

@@ -75,28 +75,28 @@ var instrumentationLibraryField = &messageValueField{
 var startTimeField = &primitiveTypedField{
 	fieldName:       "StartTime",
 	originFieldName: "StartTimeUnixNano",
-	returnType:      "TimestampUnixNano",
+	returnType:      "Timestamp",
 	rawType:         "uint64",
-	defaultVal:      "TimestampUnixNano(0)",
-	testVal:         "TimestampUnixNano(1234567890)",
+	defaultVal:      "Timestamp(0)",
+	testVal:         "Timestamp(1234567890)",
 }
 
 var timeField = &primitiveTypedField{
 	fieldName:       "Timestamp",
 	originFieldName: "TimeUnixNano",
-	returnType:      "TimestampUnixNano",
+	returnType:      "Timestamp",
 	rawType:         "uint64",
-	defaultVal:      "TimestampUnixNano(0)",
-	testVal:         "TimestampUnixNano(1234567890)",
+	defaultVal:      "Timestamp(0)",
+	testVal:         "Timestamp(1234567890)",
 }
 
 var endTimeField = &primitiveTypedField{
 	fieldName:       "EndTime",
 	originFieldName: "EndTimeUnixNano",
-	returnType:      "TimestampUnixNano",
+	returnType:      "Timestamp",
 	rawType:         "uint64",
-	defaultVal:      "TimestampUnixNano(0)",
-	testVal:         "TimestampUnixNano(1234567890)",
+	defaultVal:      "Timestamp(0)",
+	testVal:         "Timestamp(1234567890)",
 }
 
 var attributes = &sliceField{

cmd/pdatagen/internal/log_structs.go

@@ -88,10 +88,10 @@ var logRecord = &messageValueStruct{
 		&primitiveTypedField{
 			fieldName:       "Timestamp",
 			originFieldName: "TimeUnixNano",
-			returnType:      "TimestampUnixNano",
+			returnType:      "Timestamp",
 			rawType:         "uint64",
-			defaultVal:      "TimestampUnixNano(0)",
-			testVal:         "TimestampUnixNano(1234567890)",
+			defaultVal:      "Timestamp(0)",
+			testVal:         "Timestamp(1234567890)",
 		},
 		traceIDField,
 		spanIDField,

consumer/pdata/common.go

@@ -19,19 +19,10 @@ package pdata
 
 import (
 	"sort"
-	"time"
 
 	otlpcommon "go.opentelemetry.io/collector/internal/data/protogen/common/v1"
 )
 
-// TimestampUnixNano is a time specified as UNIX Epoch time in nanoseconds since
-// 00:00:00 UTC on 1 January 1970.
-type TimestampUnixNano uint64
-
-func (ts TimestampUnixNano) String() string {
-	return time.Unix(0, int64(ts)).String()
-}
-
 // AttributeValueType specifies the type of AttributeValue.
 type AttributeValueType int