Refactor label name validation

Signed-off-by: Federico Torres <[email protected]>

Author: fedetorres93

prometheus-metrics-exposition-formats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java

@@ -2,6 +2,7 @@
 
 import io.prometheus.metrics.model.snapshots.Labels;
 import io.prometheus.metrics.model.snapshots.PrometheusNaming;
+import io.prometheus.metrics.model.snapshots.ValidationScheme;
 
 import java.io.IOException;
 import java.io.OutputStreamWriter;
@@ -95,7 +96,7 @@ static void writeName(OutputStreamWriter writer, String name, NameType nameType)
                 }
                 break;
             case Label:
-                if (PrometheusNaming.isValidLegacyLabelName(name)) {
+                if (PrometheusNaming.isValidLegacyLabelName(name) && PrometheusNaming.nameValidationScheme == ValidationScheme.LEGACY_VALIDATION) {
                     writer.write(name);
                     return;
                 }

prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java

@@ -74,6 +74,16 @@ public class PrometheusNaming {
             ".total", ".created", ".bucket", ".info"
     };
 
+    static ValidationScheme initValidationScheme() {
+        if (PrometheusProperties.get() != null && PrometheusProperties.get().getNamingProperties() != null) {
+            String validationScheme = PrometheusProperties.get().getNamingProperties().getValidationScheme();
+            if (validationScheme != null && validationScheme.equals("utf-8")) {
+                return ValidationScheme.UTF_8_VALIDATION;
+            }
+        }
+        return ValidationScheme.LEGACY_VALIDATION;
+    }
+
     /**
      * Test if a metric name is valid. Rules:
      * <ul>
@@ -96,16 +106,6 @@ public static boolean isValidMetricName(String name) {
         return validateMetricName(name) == null;
     }
 
-    static ValidationScheme initValidationScheme() {
-        if (PrometheusProperties.get() != null && PrometheusProperties.get().getNamingProperties() != null) {
-            String validationScheme = PrometheusProperties.get().getNamingProperties().getValidationScheme();
-            if (validationScheme != null && validationScheme.equals("utf-8")) {
-                return ValidationScheme.UTF_8_VALIDATION;
-            }
-        }
-        return ValidationScheme.LEGACY_VALIDATION;
-    }
-
     static String validateMetricName(String name) {
         switch (nameValidationScheme) {
             case LEGACY_VALIDATION:
@@ -151,8 +151,7 @@ public static boolean isValidLegacyMetricName(String name) {
     public static boolean isValidLabelName(String name) {
         switch (nameValidationScheme) {
             case LEGACY_VALIDATION:
-                return isValidLegacyLabelName(name) &&
-                        !(name.startsWith("__") || name.startsWith("._") || name.startsWith("..") || name.startsWith("_."));
+                return isValidLegacyLabelName(name);
             case UTF_8_VALIDATION:
                 return StandardCharsets.UTF_8.newEncoder().canEncode(name);
             default:
@@ -161,14 +160,8 @@ public static boolean isValidLabelName(String name) {
     }
 
     public static boolean isValidLegacyLabelName(String name) {
-        switch (nameValidationScheme) {
-            case LEGACY_VALIDATION:
-                return LEGACY_LABEL_NAME_PATTERN.matcher(name).matches();
-            case UTF_8_VALIDATION:
-                return LABEL_NAME_PATTERN.matcher(name).matches();
-            default:
-                throw new RuntimeException("Invalid name validation scheme requested: " + nameValidationScheme);
-        }
+        return LEGACY_LABEL_NAME_PATTERN.matcher(name).matches() &&
+                !(name.startsWith("__") || name.startsWith("._") || name.startsWith("..") || name.startsWith("_."));
     }
 
     /**