Added close() method to SequencerModules to allow modules to gracefully shutdown

packages/api/src/graphql/GraphqlSequencerModule.ts

@@ -8,6 +8,7 @@ import {
   ModuleContainer,
   ModulesConfig,
   ModulesRecord,
+  noop,
   TypedClass,
 } from "@proto-kit/common";
 
@@ -74,4 +75,8 @@ export class GraphqlSequencerModule<GraphQLModules extends GraphqlModulesRecord>
     }
     void this.graphqlServer.startServer();
   }
+
+  public async close(): Promise<void> {
+    noop();
+  }
 }

packages/sdk/src/appChain/AppChain.ts

@@ -352,4 +352,8 @@ export class AppChain<
     // this.runtime.start();
     await this.sequencer.start();
   }
+
+  public async close(): Promise<void> {
+    await this.sequencer.close();
+  }
 }

packages/sdk/test/graphql/run-graphql.test.ts

@@ -1,9 +1,18 @@
-import { startServer } from "./graphql";
 import { sleep } from "@proto-kit/common";
 
+import { AppChain } from "../../src";
+
+import { startServer } from "./graphql";
+
 describe("run graphql", () => {
+  let appchain: AppChain<any, any, any, any>;
+
+  afterAll(async () => {
+    await appchain.close();
+  });
+
   it("run", async () => {
-    const server = await startServer();
+    appchain = await startServer();
     await sleep(1000000000);
   }, 1000000000);
 });

packages/sequencer/src/sequencer/builder/SequencerModule.ts

@@ -4,7 +4,7 @@ import {
   StaticConfigurableModule,
   TypedClass,
   Presets,
-  NoConfig,
+  NoConfig, noop
 } from "@proto-kit/common";
 import { injectable } from "tsyringe";
 
@@ -24,6 +24,15 @@ export abstract class SequencerModule<
    * That means that you mustn't await server.start() for example.
    */
   public abstract start(): Promise<void>;
+
+  /**
+   * Close() is called by the sequencer when the appchain or the sequencer
+   * is in the process of stopping.
+   * Possible usages are stopping of API services, closing of database connections, ...
+   */
+  public async close(): Promise<void> {
+    noop();
+  }
 }
 
 /**

packages/sequencer/src/sequencer/executor/Sequencer.ts

@@ -6,7 +6,11 @@ import {
   ModuleContainerDefinition,
   log,
 } from "@proto-kit/common";
-import { Runtime, RuntimeModulesRecord, MethodIdFactory } from "@proto-kit/module";
+import {
+  Runtime,
+  RuntimeModulesRecord,
+  MethodIdFactory,
+} from "@proto-kit/module";
 import { Protocol, ProtocolModulesRecord } from "@proto-kit/protocol";
 import { DependencyContainer, injectable } from "tsyringe";
 
@@ -87,4 +91,23 @@ export class Sequencer<Modules extends SequencerModulesRecord>
       await sequencerModule.start();
     }
   }
+
+  public async close(): Promise<void> {
+    let counter = 0;
+
+    const { modules } = this.definition;
+    const totalModules = Object.keys(modules).length;
+
+    for (const moduleName in modules) {
+      const sequencerModule = this.resolve(moduleName);
+
+      log.info(
+        `Closing sequencer module ${moduleName} (${
+          sequencerModule.constructor.name
+        }) ${++counter}/${totalModules}`
+      );
+      // eslint-disable-next-line no-await-in-loop
+      await sequencerModule.close();
+    }
+  }
 }