CORDA-2653 - ensure that during initialisation of a Corda Service, the current thread has a context classloader. (#4907)

node/src/main/kotlin/net/corda/node/internal/AbstractNode.kt

@@ -575,6 +575,15 @@ abstract class AbstractNode<S>(val configuration: NodeConfiguration,
 
     private fun installCordaServices() {
         val loadedServices = cordappLoader.cordapps.flatMap { it.services }
+
+        // This sets the Cordapp classloader on the contextClassLoader of the current thread, prior to initializing services
+        // Needed because of bug CORDA-2653 - some Corda services can utilise third-party libraries that require access to
+        // the Thread context class loader
+
+        val oldContextClassLoader : ClassLoader? = Thread.currentThread().contextClassLoader
+        try {
+            Thread.currentThread().contextClassLoader = cordappLoader.appClassLoader
+
             loadedServices.forEach {
                 try {
                     installCordaService(it)
@@ -591,6 +600,9 @@ abstract class AbstractNode<S>(val configuration: NodeConfiguration,
                     log.error("Unable to install Corda service ${it.name}", e)
                 }
             }
+        } finally {
+            Thread.currentThread().contextClassLoader = oldContextClassLoader
+        }
     }
 
     /**

node/src/test/kotlin/net/corda/node/internal/CordaServiceTest.kt

@@ -26,10 +26,7 @@ import org.junit.After
 import org.junit.Before
 import org.junit.Test
 import java.util.concurrent.atomic.AtomicInteger
-import kotlin.test.assertEquals
+import kotlin.test.*
-import kotlin.test.assertFailsWith
-import kotlin.test.assertNotEquals
-import kotlin.test.assertTrue
 
 class CordaServiceTest {
     private lateinit var mockNet: MockNetwork
@@ -77,6 +74,12 @@ class CordaServiceTest {
         service.startServiceFlowAndTrack()
     }
 
+    @Test
+    fun `Corda service can access a non-null thread context classloader`() {
+        val service = nodeA.services.cordaService(CordaServiceThatRequiresThreadContextClassLoader::class.java)
+        service.thatWeCanAccessClassLoader()
+    }
+
     /**
      * Reproduce CORDA-2296
      * Querying the vault from a services constructor failed because the criteriaBuilder
@@ -142,4 +145,19 @@ class CordaServiceTest {
             serviceHub.vaultService.trackBy(ContractState::class.java, criteria)
         }
     }
+
+    /**
+     * See: CORDA-2653
+     * This is to check that a corda service is presented with a non-null thread context classloader
+     */
+    @CordaService
+    class CordaServiceThatRequiresThreadContextClassLoader(val serviceHub: AppServiceHub) : SingletonSerializeAsToken() {
+        init {
+            assertNotNull(Thread.currentThread().contextClassLoader, "thread context classloader should not be null during service initialisation")
+        }
+
+        fun thatWeCanAccessClassLoader() {
+            assertNotNull(Thread.currentThread().contextClassLoader, "thread context classloader should not be null during service initialisation")
+        }
+    }
 }