Add validation heartbeat metric (#15)

Author: pboos

openapi-validation-api/src/main/java/com/getyourguide/openapi/validation/api/metrics/DefaultMetricsReporter.java

@@ -16,14 +16,17 @@ public class DefaultMetricsReporter implements MetricsReporter {
 
     @Override
     public void reportViolation(OpenApiViolation violation) {
-        String violationMetricName = buildMetricName(".error");
-        metricsClient.increment(violationMetricName, createTagsForViolation(violation));
+        metricsClient.increment(buildMetricName(".error"), createTagsForViolation(violation));
     }
 
     @Override
     public void reportStartup(boolean isValidationEnabled) {
-        String startupMetricName = buildMetricName(".startup");
-        metricsClient.increment(startupMetricName, createTagsForStartup(isValidationEnabled));
+        metricsClient.increment(buildMetricName(".startup"), createTagsForStartup(isValidationEnabled));
+    }
+
+    @Override
+    public void reportValidationHeartbeat() {
+        metricsClient.increment(buildMetricName(".validation_heartbeat"), createTagsForValidation());
     }
 
     private String buildMetricName(String suffix) {
@@ -53,6 +56,12 @@ private MetricTag[] createTagsForStartup(boolean isValidationEnabled) {
         return tags.toArray(MetricTag[]::new);
     }
 
+    private MetricTag[] createTagsForValidation() {
+        var tags = new ArrayList<MetricTag>();
+        addAdditionalTags(tags);
+        return tags.toArray(MetricTag[]::new);
+    }
+
     private void addAdditionalTags(ArrayList<MetricTag> tags) {
         if (configuration.getMetricAdditionalTags() != null) {
             tags.addAll(configuration.getMetricAdditionalTags());

openapi-validation-api/src/main/java/com/getyourguide/openapi/validation/api/metrics/MetricsReporter.java

@@ -6,4 +6,6 @@ public interface MetricsReporter {
     void reportViolation(OpenApiViolation violation);
 
     void reportStartup(boolean isValidationEnabled);
+
+    void reportValidationHeartbeat();
 }

openapi-validation-core/src/main/java/com/getyourguide/openapi/validation/core/OpenApiRequestValidator.java

@@ -19,9 +19,14 @@
 
 @Slf4j
 public class OpenApiRequestValidator {
+    public static final int METRIC_REPORT_VALIDATION_HEARTBEAT_FREQUENCY_MILLIS = 60 * 60 * 1000; // 1h
+
     private final ThreadPoolExecutor threadPoolExecutor;
     private final OpenApiInteractionValidatorWrapper validator;
     private final ValidationReportHandler validationReportHandler;
+    private final MetricsReporter metricsReporter;
+
+    private long lastReportValidationDateTime = 0;
 
     public OpenApiRequestValidator(
         ThreadPoolExecutor threadPoolExecutor,
@@ -33,6 +38,7 @@ public OpenApiRequestValidator(
         this.threadPoolExecutor = threadPoolExecutor;
         this.validator = new OpenApiInteractionValidatorFactory().build(specificationFilePath, configuration);
         this.validationReportHandler = validationReportHandler;
+        this.metricsReporter = metricsReporter;
 
         metricsReporter.reportStartup(validator != null);
     }
@@ -62,6 +68,7 @@ public ValidationResult validateRequestObject(final RequestMetaData request, Str
             var simpleRequest = buildSimpleRequest(request, requestBody);
             var result = validator.validateRequest(simpleRequest);
             validationReportHandler.handleValidationReport(request, Direction.REQUEST, requestBody, result);
+            reportValidationHeartbeat();
             return buildValidationResult(result);
         } catch (Exception e) {
             log.error("Could not validate request", e);
@@ -99,6 +106,7 @@ public ValidationResult validateResponseObject(
                 responseBuilder.build()
             );
             validationReportHandler.handleValidationReport(request, Direction.RESPONSE, responseBody, result);
+            reportValidationHeartbeat();
             return buildValidationResult(result);
         } catch (Exception e) {
             log.error("Could not validate response", e);
@@ -117,4 +125,12 @@ private ValidationResult buildValidationResult(ValidationReport validationReport
 
         return ValidationResult.INVALID;
     }
+
+    private synchronized void reportValidationHeartbeat() {
+        var currentTimeMillis = System.currentTimeMillis();
+        if (lastReportValidationDateTime + METRIC_REPORT_VALIDATION_HEARTBEAT_FREQUENCY_MILLIS < currentTimeMillis) {
+            lastReportValidationDateTime = currentTimeMillis;
+            metricsReporter.reportValidationHeartbeat();
+        }
+    }
 }