Send GOODBYE message before closing connections in Bolt V3

To make the database know that connection is being terminated
intentionally. No such message is sent in Bolt V1 and V2.

Author: lutovich

src/v1/internal/bolt-protocol-v1.js

@@ -72,6 +72,10 @@ export default class BoltProtocol {
     this._connection.write(message, observer, true);
   }
 
+  prepareToClose(observer) {
+    // no need to notify the database in this protocol version
+  }
+
   /**
    * Begin an explicit transaction.
    * @param {Bookmark} bookmark the bookmark.

src/v1/internal/bolt-protocol-v3.js

@@ -47,6 +47,11 @@ export default class BoltProtocol extends BoltProtocolV2 {
     this._connection.write(message, observer, true);
   }
 
+  prepareToClose(observer) {
+    const message = RequestMessage.goodbye();
+    this._connection.write(message, observer, true);
+  }
+
   beginTransaction(bookmark, txConfig, observer) {
     prepareToHandleSingleResponse(observer);
     const message = RequestMessage.begin(bookmark, txConfig);

src/v1/internal/connection.js

@@ -382,11 +382,23 @@ export default class Connection {
    * Call close on the channel.
    * @param {function} cb - Function to call on close.
    */
-  close(cb) {
+  close(cb = (() => null)) {
     if (this._log.isDebugEnabled()) {
       this._log.debug(`${this} closing`);
     }
-    this._ch.close(cb);
+
+    if (this._protocol) {
+      // protocol has been initialized
+      // use it to notify the database about the upcoming close of the connection
+      this._protocol.prepareToClose(NO_OP_OBSERVER);
+    }
+
+    this._ch.close(() => {
+      if (this._log.isDebugEnabled()) {
+        this._log.debug(`${this} closed`);
+      }
+      cb();
+    });
   }
 
   toString() {

src/v1/internal/request-message.js

@@ -26,6 +26,7 @@ const DISCARD_ALL = 0x2F;     // 0010 1111 // DISCARD_ALL - unused
 const PULL_ALL = 0x3F;        // 0011 1111 // PULL_ALL
 
 const HELLO = 0x01;           // 0000 0001 // HELLO <metadata>
+const GOODBYE = 0x02;         // 0000 0010 // GOODBYE
 const BEGIN = 0x11;           // 0001 0001 // BEGIN <metadata>
 const COMMIT = 0x12;          // 0001 0010 // COMMIT
 const ROLLBACK = 0x13;        // 0001 0011 // ROLLBACK
@@ -125,6 +126,14 @@ export default class RequestMessage {
     return new RequestMessage(RUN, [statement, parameters, metadata],
       () => `RUN ${statement} ${JSON.stringify(parameters)} ${JSON.stringify(metadata)}`);
   }
+
+  /**
+   * Get a GOODBYE message.
+   * @return {RequestMessage} the GOODBYE message.
+   */
+  static goodbye() {
+    return GOODBYE_MESSAGE;
+  }
 }
 
 /**
@@ -152,3 +161,4 @@ const PULL_ALL_MESSAGE = new RequestMessage(PULL_ALL, [], () => 'PULL_ALL');
 const RESET_MESSAGE = new RequestMessage(RESET, [], () => 'RESET');
 const COMMIT_MESSAGE = new RequestMessage(COMMIT, [], () => 'COMMIT');
 const ROLLBACK_MESSAGE = new RequestMessage(ROLLBACK, [], () => 'ROLLBACK');
+const GOODBYE_MESSAGE = new RequestMessage(GOODBYE, [], () => 'GOODBYE');

test/internal/connection.test.js

@@ -32,6 +32,7 @@ import ConnectionErrorHandler from '../../src/v1/internal/connection-error-handl
 import testUtils from '../internal/test-utils';
 import Bookmark from '../../src/v1/internal/bookmark';
 import TxConfig from '../../src/v1/internal/tx-config';
+import boltStub from '../internal/bolt-stub';
 
 const ILLEGAL_MESSAGE = {signature: 42, fields: []};
 const SUCCESS_MESSAGE = {signature: 0x70, fields: [{}]};
@@ -346,6 +347,29 @@ describe('Connection', () => {
     connection._handleFatalError(newError('Hello', SERVICE_UNAVAILABLE));
   });
 
+  it('should send hello and goodbye messages', done => {
+    if (!boltStub.supported) {
+      done();
+      return;
+    }
+
+    const server = boltStub.start('./test/resources/boltstub/hello_goodbye.script', 9001);
+
+    boltStub.run(() => {
+      connection = createConnection('bolt://127.0.0.1:9001', {encrypted: false});
+      connection.connect('single-connection/1.2.3', basicAuthToken())
+        .then(() => {
+          connection.close(() => {
+            server.exit(code => {
+              expect(code).toEqual(0);
+              done();
+            });
+          });
+        })
+        .catch(error => done.fail(error));
+    });
+  });
+
   function packedHandshakeMessage() {
     const result = alloc(4);
     result.putInt32(0, 1);

test/internal/request-message.test.js

@@ -115,4 +115,11 @@ describe('RequestMessage', () => {
     expect(message.toString()).toEqual(`RUN ${statement} ${JSON.stringify(parameters)} ${JSON.stringify(expectedMetadata)}`);
   });
 
+  it('should create GOODBYE message', () => {
+    const message = RequestMessage.goodbye();
+
+    expect(message.signature).toEqual(0x02);
+    expect(message.fields).toEqual([]);
+    expect(message.toString()).toEqual('GOODBYE');
+  });
 });

test/resources/boltstub/hello_goodbye.script

@@ -0,0 +1,6 @@
+!: BOLT 3
+
+C: HELLO {"credentials": "password", "scheme": "basic", "user_agent": "single-connection/1.2.3", "principal": "neo4j"}
+S: SUCCESS {"server": "Neo4j/9.9.9"}
+C: GOODBYE
+S: SUCCESS {}

test/resources/boltstub/hello_run_goodbye.script

@@ -0,0 +1,13 @@
+!: BOLT 3
+!: AUTO RESET
+
+C: HELLO {"credentials": "password", "scheme": "basic", "user_agent": "neo4j-javascript/0.0.0-dev", "principal": "neo4j"}
+S: SUCCESS {"server": "Neo4j/9.9.9"}
+C: RUN "MATCH (n) RETURN n.name" {} {}
+   PULL_ALL
+S: SUCCESS {"fields": ["n.name"]}
+   RECORD ["Foo"]
+   RECORD ["Bar"]
+   SUCCESS {}
+C: GOODBYE
+S: SUCCESS {}

test/v1/direct.driver.boltkit.test.js

@@ -333,4 +333,33 @@ describe('direct driver with stub server', () => {
     });
   });
 
+  it('should send goodbye message when closed', done => {
+    if (!boltStub.supported) {
+      done();
+      return;
+    }
+
+    const server = boltStub.start('./test/resources/boltstub/hello_run_goodbye.script', 9001);
+
+    boltStub.run(() => {
+      const driver = boltStub.newDriver('bolt://127.0.0.1:9001');
+      const session = driver.session();
+
+      session.run('MATCH (n) RETURN n.name')
+        .then(result => {
+          const names = result.records.map(record => record.get('n.name'));
+          expect(names).toEqual(['Foo', 'Bar']);
+
+          session.close(() => {
+            driver.close();
+            server.exit(code => {
+              expect(code).toEqual(0);
+              done();
+            });
+          });
+        })
+        .catch(error => done.fail(error));
+    });
+  });
+
 });