Provide custom BackgroundExecutorWrapper to pass thread locals

(cherry picked from commit 336accf447)

ebean-test/src/test/java/org/tests/cache/TestBeanCacheAsync.java

@@ -0,0 +1,113 @@
+package org.tests.cache;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.util.concurrent.Callable;
+
+import org.junit.jupiter.api.Test;
+import org.tests.model.basic.OCachedBean;
+
+import io.ebean.BaseTestCase;
+import io.ebean.DB;
+import io.ebean.Database;
+import io.ebean.DatabaseFactory;
+import io.ebean.config.CurrentTenantProvider;
+import io.ebean.config.DatabaseConfig;
+import io.ebean.config.MdcBackgroundExecutorWrapper;
+import io.ebeaninternal.server.cache.DefaultServerCachePlugin;
+
+/**
+ * Test class testing async/background cache updates in a multi-tenant environment. 
+ */
+public class TestBeanCacheAsync extends BaseTestCase {
+
+  private final ThreadLocal<String> tenantId = new ThreadLocal<>();
+
+  class ThreadLocalTenantProvider implements CurrentTenantProvider {
+
+    @Override
+    public Object currentId() {
+      return tenantId.get();
+    }
+  }
+  /**
+   * Copy tenant info to the background thread.
+   */
+  class TenantCopyBackgroundExecutorWrapper extends MdcBackgroundExecutorWrapper {
+    @Override
+    public <T> Callable<T> wrap(Callable<T> task) {
+      String tenant = tenantId.get();
+      if (tenant == null) {
+        return super.wrap(task);
+      } else {
+        return () -> {
+          tenantId.set(tenant);
+          try {
+            return super.wrap(task).call();
+          } finally {
+            tenantId.remove();
+          }
+        };
+      }
+    }
+    
+    @Override
+    public Runnable wrap(Runnable task) {
+      String tenant = tenantId.get();
+      if (tenant == null) {
+        return super.wrap(task);
+      } else {
+        return () -> {
+          tenantId.set(tenant);
+          try {
+            super.wrap(task).run();
+          } finally {
+            tenantId.remove();
+          }
+        };
+      }
+    }
+  }
+  
+  @Test
+  public void findById_with_tenant() throws InterruptedException {
+    DatabaseConfig config = new DatabaseConfig();
+    config.setName(DB.getDefault().name());
+    config.loadFromProperties();
+    config.setDataSource(DB.getDefault().dataSource());
+    config.setReadOnlyDataSource(DB.getDefault().readOnlyDataSource());
+    config.setDdlExtra(false);
+    config.setDdlGenerate(false);
+    config.setDdlRun(false);
+    config.setDefaultServer(false);
+    config.setRegister(false);
+    config.setServerCachePlugin(new DefaultServerCachePlugin()); // disables foreground local caching (as it is done in Hz/Ignite)
+    config.setCurrentTenantProvider(new ThreadLocalTenantProvider());
+    config.setBackgroundExecutorWrapper(new TenantCopyBackgroundExecutorWrapper());
+    tenantId.set("4711");
+    
+    Database db = DatabaseFactory.create(config);
+    try {
+      OCachedBean bean = new OCachedBean();
+      bean.setName("findById");
+      db.save(bean);
+
+      OCachedBean bean0 = db.find(OCachedBean.class, bean.getId());
+      assertNotNull(bean0);
+      assertThat(bean0.getName()).isEqualTo("findById");
+      bean0.setName("findById2");
+      db.save(bean0);
+
+      Thread.sleep(100); // TODO: can we block finds on that ID if a pending cache update is present?
+      
+      bean0 = db.find(OCachedBean.class, bean.getId());
+      assertNotNull(bean0);
+      assertThat(bean0.getName()).isEqualTo("findById2");
+
+    } finally {
+      db.shutdown();
+    }
+  }
+
+}