Feat: Fix trimming for non-space whitespace (#10)

Previously, trimming would only happen at the first space, which is
an issue when the operation name is separated by another whitespace
character like a newline.

tracer.go

@@ -60,6 +60,21 @@ func recordError(span trace.Span, err error) {
 	}
 }
 
+const sqlOperationUnknkown = "UNKNOWN"
+
+// sqlOperationName attempts to get the first 'word' from a given SQL query, which usually
+// is the operation name (e.g. 'SELECT').
+func sqlOperationName(query string) string {
+	parts := strings.Fields(query)
+	if len(parts) == 0 {
+		// Fall back to a fixed value to prevent creating lots of tracing operations
+		// differing only by the amount of whitespace in them (in case we'd fall back
+		// to the full query or a cut-off version).
+		return sqlOperationUnknkown
+	}
+	return strings.ToUpper(parts[0])
+}
+
 func appendConnectionAttributes(config *pgx.ConnConfig, opts []trace.SpanStartOption) {
 	if config != nil {
 		opts = append(opts,
@@ -91,7 +106,7 @@ func (t *Tracer) TraceQueryStart(ctx context.Context, conn *pgx.Conn, data pgx.T
 
 	spanName := "query " + data.SQL
 	if t.trimQuerySpanName {
-		spanName = "query " + strings.Split(data.SQL, " ")[0]
+		spanName = "query " + sqlOperationName(data.SQL)
 	}
 
 	ctx, _ = t.tracer.Start(ctx, spanName, opts...)
@@ -183,7 +198,7 @@ func (t *Tracer) TraceBatchQuery(ctx context.Context, conn *pgx.Conn, data pgx.T
 
 	spanName := "batch query " + data.SQL
 	if t.trimQuerySpanName {
-		spanName = "query " + strings.Split(data.SQL, " ")[0]
+		spanName = "query " + sqlOperationName(data.SQL)
 	}
 
 	_, span := t.tracer.Start(ctx, spanName, opts...)
@@ -253,7 +268,7 @@ func (t *Tracer) TracePrepareStart(ctx context.Context, conn *pgx.Conn, data pgx
 
 	spanName := "prepare " + data.SQL
 	if t.trimQuerySpanName {
-		spanName = "prepare " + strings.Split(data.SQL, " ")[0]
+		spanName = "prepare " + sqlOperationName(data.SQL)
 	}
 
 	ctx, _ = t.tracer.Start(ctx, spanName, opts...)

tracer_test.go

@@ -0,0 +1,46 @@
+package otelpgx
+
+import "testing"
+
+func TestSqlOperationName(t *testing.T) {
+	tests := []struct {
+		name    string
+		query   string
+		expName string
+	}{
+		{
+			name:    "Spaces only",
+			query:   "SELECT * FROM users",
+			expName: "SELECT",
+		},
+		{
+			name:    "Newline and tab",
+			query:   "UPDATE\n\tfoo",
+			expName: "UPDATE",
+		},
+		{
+			name:    "Additional whitespace",
+			query:   " \n SELECT\n\t   *   FROM users  ",
+			expName: "SELECT",
+		},
+		{
+			name:    "Whitespace-only query",
+			query:   " \n\t",
+			expName: "UNKNOWN",
+		},
+		{
+			name:    "Empty query",
+			query:   "",
+			expName: "UNKNOWN",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			name := sqlOperationName(tt.query)
+			if name != tt.expName {
+				t.Errorf("Got name %q, expected %q", name, tt.expName)
+			}
+		})
+	}
+}