openapi3: fix ineffectual caching of compiled regexps (#1076)

* Fix openapi regex caching.

* Remove stray line

Author: philpearl

openapi3/schema_pattern.go

@@ -30,6 +30,6 @@ func (schema *Schema) compilePattern(c RegexCompilerFunc) (cp RegexMatcher, err
 		return
 	}
 
-	var _ bool = compiledPatterns.CompareAndSwap(pattern, nil, cp)
+	compiledPatterns.Store(pattern, cp)
 	return
 }

openapi3/schema_pattern_test.go

@@ -17,3 +17,17 @@ func TestPattern(t *testing.T) {
 	require.Equal(t, `^[a-zA-Z\x{0080}-\x{024F}]+$`, intoGoRegexp(`^[a-zA-Z\u0080-\u024F]+$`))
 	require.Equal(t, `^[6789a-zA-Z\x{0080}-\x{024F}]+$`, intoGoRegexp(`^[6789a-zA-Z\u0080-\u024F]+$`))
 }
+
+func TestSchemaPatternCache(t *testing.T) {
+	var schema Schema
+
+	schema.Pattern = `^[a-zA-Z\x{0080}-\x{024F}]+$`
+	cp, err := schema.compilePattern(nil)
+	require.NoError(t, err)
+	require.NotNil(t, cp)
+
+	// The compiled pattern should be cached
+	v, ok := compiledPatterns.Load(schema.Pattern)
+	require.True(t, ok)
+	require.Equal(t, cp, v)
+}