Support virtual threads (#215)

Author: pboos

README.md

@@ -102,6 +102,9 @@ openapi.validation.validation-report-metric-additional-tags=service=example,team
 # Fail requests on request/response violations. Defaults to false.
 openapi.validation.should-fail-on-request-violation=true
 openapi.validation.should-fail-on-response-violation=true
+
+# Enable virtual threads for async validation. Defaults to false.
+openapi.validation.enable-virtual-threads=true
 ```
 
 ### DataDog metrics

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

@@ -14,26 +14,26 @@
 import java.net.URLDecoder;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
+import java.util.concurrent.Executor;
 import java.util.concurrent.RejectedExecutionException;
-import java.util.concurrent.ThreadPoolExecutor;
 import javax.annotation.Nullable;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.http.client.utils.URLEncodedUtils;
 
 @Slf4j
 public class OpenApiRequestValidator {
-    private final ThreadPoolExecutor threadPoolExecutor;
+    private final Executor executor;
     private final OpenApiInteractionValidatorWrapper validator;
     private final ValidationReportToOpenApiViolationsMapper mapper;
 
     public OpenApiRequestValidator(
-        ThreadPoolExecutor threadPoolExecutor,
+        Executor executor,
         MetricsReporter metricsReporter,
         OpenApiInteractionValidatorWrapper validator,
         ValidationReportToOpenApiViolationsMapper mapper,
         OpenApiRequestValidationConfiguration configuration
     ) {
-        this.threadPoolExecutor = threadPoolExecutor;
+        this.executor = executor;
         this.validator = validator;
         this.mapper = mapper;
 
@@ -74,7 +74,7 @@ public void validateResponseObjectAsync(
 
     private void executeAsync(Runnable command) {
         try {
-            threadPoolExecutor.execute(command);
+            executor.execute(command);
         } catch (RejectedExecutionException ignored) {
             // ignored
         }

openapi-validation-core/src/main/java/com/getyourguide/openapi/validation/core/executor/VirtualThreadLimitedExecutor.java

@@ -0,0 +1,54 @@
+package com.getyourguide.openapi.validation.core.executor;
+
+import java.util.concurrent.Executor;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class VirtualThreadLimitedExecutor implements Executor {
+    private static final int DEFAULT_MAX_CONCURRENT = 2;
+    private final int maxConcurrent;
+    private final AtomicInteger runningCount = new AtomicInteger(0);
+
+    public VirtualThreadLimitedExecutor() {
+        this(DEFAULT_MAX_CONCURRENT);
+    }
+
+    public VirtualThreadLimitedExecutor(int maxConcurrent) {
+        checkVirtualThreadSupport();
+        this.maxConcurrent = maxConcurrent;
+    }
+
+    public static boolean isSupported() {
+        try {
+            checkVirtualThreadSupport();
+            return true;
+        } catch (UnsupportedOperationException | NoSuchMethodError e) {
+            return false;
+        }
+    }
+
+    private static void checkVirtualThreadSupport() {
+        // This will throw NoSuchMethodError on Java < 21
+        //noinspection ResultOfMethodCallIgnored
+        Thread.ofVirtual();
+    }
+
+    @Override
+    public void execute(Runnable command) {
+        if (runningCount.get() >= maxConcurrent) {
+            return;
+        }
+
+        if (runningCount.incrementAndGet() > maxConcurrent) {
+            runningCount.decrementAndGet();
+            return;
+        }
+
+        Thread.ofVirtual().start(() -> {
+            try {
+                command.run();
+            } finally {
+                runningCount.decrementAndGet();
+            }
+        });
+    }
+}

openapi-validation-core/src/test/java/com/getyourguide/openapi/validation/core/OpenApiRequestValidatorTest.java

@@ -14,30 +14,30 @@
 import java.net.URI;
 import java.util.HashMap;
 import java.util.List;
+import java.util.concurrent.Executor;
 import java.util.concurrent.RejectedExecutionException;
-import java.util.concurrent.ThreadPoolExecutor;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mockito;
 
 public class OpenApiRequestValidatorTest {
 
-    private ThreadPoolExecutor threadPoolExecutor;
+    private Executor executor;
     private OpenApiInteractionValidatorWrapper validator;
 
     private OpenApiRequestValidator openApiRequestValidator;
 
     @BeforeEach
     public void setup() {
-        threadPoolExecutor = mock();
+        executor = mock();
         validator = mock();
         MetricsReporter metricsReporter = mock();
         var mapper = mock(ValidationReportToOpenApiViolationsMapper.class);
         when(mapper.map(any(), any(), any(), any(), any())).thenReturn(List.of());
 
         openApiRequestValidator = new OpenApiRequestValidator(
-            threadPoolExecutor,
+            executor,
             metricsReporter,
             validator,
             mapper,
@@ -47,7 +47,7 @@ public void setup() {
 
     @Test
     public void testWhenThreadPoolExecutorRejectsExecutionThenItShouldNotThrow() {
-        Mockito.doThrow(new RejectedExecutionException()).when(threadPoolExecutor).execute(any());
+        Mockito.doThrow(new RejectedExecutionException()).when(executor).execute(any());
 
         openApiRequestValidator.validateRequestObjectAsync(mock(), null, null, mock());
     }

spring-boot-starter/spring-boot-starter-core/src/main/java/com/getyourguide/openapi/validation/OpenApiValidationApplicationProperties.java

@@ -38,6 +38,7 @@ public class OpenApiValidationApplicationProperties {
     private List<String> excludedHeaders;
     private Boolean shouldFailOnRequestViolation;
     private Boolean shouldFailOnResponseViolation;
+    private Boolean enableVirtualThreads;
 
     public double getSampleRate() {
         return sampleRate != null ? sampleRate : SAMPLE_RATE_DEFAULT;
@@ -84,6 +85,10 @@ public List<ExcludedHeader> getExcludedHeaders() {
             .toList();
     }
 
+    public boolean isEnableVirtualThreads() {
+        return enableVirtualThreads != null ? enableVirtualThreads : false;
+    }
+
     public OpenApiRequestValidationConfiguration toOpenApiRequestValidationConfiguration() {
         return OpenApiRequestValidationConfiguration.builder()
             .sampleRate(getSampleRate())

spring-boot-starter/spring-boot-starter-core/src/main/java/com/getyourguide/openapi/validation/autoconfigure/LibraryAutoConfiguration.java

@@ -19,12 +19,14 @@
 import com.getyourguide.openapi.validation.core.OpenApiInteractionValidatorFactory;
 import com.getyourguide.openapi.validation.core.OpenApiRequestValidator;
 import com.getyourguide.openapi.validation.core.exclusions.InternalViolationExclusions;
+import com.getyourguide.openapi.validation.core.executor.VirtualThreadLimitedExecutor;
 import com.getyourguide.openapi.validation.core.log.DefaultOpenApiViolationHandler;
 import com.getyourguide.openapi.validation.core.log.ExclusionsOpenApiViolationHandler;
 import com.getyourguide.openapi.validation.core.log.ThrottlingOpenApiViolationHandler;
 import com.getyourguide.openapi.validation.core.mapper.ValidationReportToOpenApiViolationsMapper;
 import com.getyourguide.openapi.validation.core.metrics.DefaultMetricsReporter;
 import java.util.Optional;
+import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -104,14 +106,7 @@ public OpenApiRequestValidator openApiRequestValidator(
         MetricsReporter metricsReporter,
         ValidatorConfiguration validatorConfiguration
     ) {
-        var threadPoolExecutor = new ThreadPoolExecutor(
-            2,
-            2,
-            1000L,
-            TimeUnit.MILLISECONDS,
-            new LinkedBlockingQueue<>(10),
-            new ThreadPoolExecutor.DiscardPolicy()
-        );
+        var threadPoolExecutor = createThreadPoolExecutor();
 
         return new OpenApiRequestValidator(
             threadPoolExecutor,
@@ -122,4 +117,20 @@ public OpenApiRequestValidator openApiRequestValidator(
             properties.toOpenApiRequestValidationConfiguration()
         );
     }
+
+    private Executor createThreadPoolExecutor() {
+        if (properties.isEnableVirtualThreads() && VirtualThreadLimitedExecutor.isSupported()) {
+            return new VirtualThreadLimitedExecutor();
+        }
+
+        // Fallback to ThreadPoolExecutor with regular threads
+        return new ThreadPoolExecutor(
+            2,
+            2,
+            1000L,
+            TimeUnit.MILLISECONDS,
+            new LinkedBlockingQueue<>(10),
+            new ThreadPoolExecutor.DiscardPolicy()
+        );
+    }
 }

spring-boot-starter/spring-boot-starter-core/src/test/java/com/getyourguide/openapi/validation/OpenApiValidationApplicationPropertiesTest.java

@@ -34,7 +34,8 @@ void getters() {
             EXCLUDED_PATHS,
             EXCLUDED_HEADERS,
             true,
-            false
+            false,
+            true
         );
 
         assertEquals(SAMPLE_RATE, loggingConfiguration.getSampleRate());