Introduce Driver.getServerInfo method (#878)

This is part of the drivers unification initiative.

The `Driver.verifyConnectivity` method was implemented in different ways across the drivers with different returns value. For consistency and clarity about what the method does, the new behaviour of the `Driver.verifyConnectivity` is check the connectivity with all the readers available and then returns a resolve empty promise in case of success (the promise will be rejected, otherwise).

The Server Info information was moved to the method `Driver.getSeverInfo` which verifies the connectivity and then returns the `ServerInfo` of one of the read servers.

For keeping the backwards compatibility, the `Driver.verifyConnectivity` was deprecated in this version and it should be replace with a version with `Promise<void>` as return value in the next major release. `Driver.getServerInfo` should be used instead if the client code needs the server information.

Author: bigmontz

packages/bolt-connection/src/connection-provider/connection-provider-direct.js

@@ -103,4 +103,8 @@ export default class DirectConnectionProvider extends PooledConnectionProvider {
       version => version >= BOLT_PROTOCOL_V4_4
     )
   }
+
+  async verifyConnectivityAndGetServerInfo () {
+    return await this._verifyConnectivityAndGetServerVersion({ address: this._address })
+  }
 }

packages/bolt-connection/src/connection-provider/connection-provider-pooled.js

@@ -19,7 +19,7 @@
 
 import { createChannelConnection, ConnectionErrorHandler } from '../connection'
 import Pool, { PoolConfig } from '../pool'
-import { error, ConnectionProvider } from 'neo4j-driver-core'
+import { error, ConnectionProvider, ServerInfo } from 'neo4j-driver-core'
 
 const { SERVICE_UNAVAILABLE } = error
 export default class PooledConnectionProvider extends ConnectionProvider {
@@ -109,6 +109,23 @@ export default class PooledConnectionProvider extends ConnectionProvider {
     return conn.close()
   }
 
+  /**
+   * Acquire a connection from the pool and return it ServerInfo
+   * @param {object} param
+   * @param {string} param.address the server address
+   * @return {Promise<ServerInfo>} the server info
+   */
+  async _verifyConnectivityAndGetServerVersion ({ address }) {
+    const connection = await this._connectionPool.acquire(address)
+    const serverInfo = new ServerInfo(connection.server, connection.protocol().version)
+    try {
+      await connection.resetAndFlush()
+    } finally {
+      await connection._release()
+    }
+    return serverInfo
+  }
+
   async close () {
     // purge all idle connections in the connection pool
     await this._connectionPool.close()

packages/bolt-connection/src/connection-provider/connection-provider-routing.js

@@ -237,7 +237,24 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     return await this._hasProtocolVersion(
       version => version >= BOLT_PROTOCOL_V4_4
     )
-  }  
+  }
+
+  async verifyConnectivityAndGetServerInfo ({ database, accessMode }) {
+    const context = { database: database || DEFAULT_DB_NAME }
+
+    const routingTable = await this._freshRoutingTable({
+      accessMode,
+      database: context.database,
+      onDatabaseNameResolved: (databaseName) => {
+        context.database = context.database || databaseName
+      }
+    })
+
+    const servers = accessMode === WRITE ? routingTable.writers : routingTable.readers
+
+    return Promise.all(servers.map(address => this._verifyConnectivityAndGetServerVersion({ address })))
+      .then(([serverInfo]) => serverInfo)
+  }
 
   forget (address, database) {
     this._routingTableRegistry.apply(database, {

packages/bolt-connection/src/pool/pool.js

@@ -71,7 +71,7 @@ class Pool {
   /**
    * Acquire and idle resource fom the pool or create a new one.
    * @param {ServerAddress} address the address for which we're acquiring.
-   * @return {Object} resource that is ready to use.
+   * @return {Promise<Object>} resource that is ready to use.
    */
   acquire (address) {
     const key = address.asKey()

packages/bolt-connection/test/connection-provider/connection-provider-direct.test.js

@@ -20,7 +20,7 @@
 import DirectConnectionProvider from '../../src/connection-provider/connection-provider-direct'
 import { Pool } from '../../src/pool'
 import { Connection, DelegateConnection } from '../../src/connection'
-import { internal, newError } from 'neo4j-driver-core'
+import { internal, newError, ServerInfo } from 'neo4j-driver-core'
 
 const {
   serverAddress: { ServerAddress },
@@ -139,6 +139,180 @@ it('should not change error when TokenExpired happens', async () => {
   expect(error).toBe(expectedError)
 })
 
+describe('.verifyConnectivityAndGetServerInfo()', () => {
+  describe('when connection is available in the pool', () => {
+    it('should return the server info', async () => {
+      const { connectionProvider, server, protocolVersion } = setup()
+
+      const serverInfo = await connectionProvider.verifyConnectivityAndGetServerInfo()
+
+      expect(serverInfo).toEqual(new ServerInfo(server, protocolVersion))
+    })
+
+    it('should reset and flush the connection', async () => {
+      const { connectionProvider, resetAndFlush } = setup()
+
+      await connectionProvider.verifyConnectivityAndGetServerInfo()
+
+      expect(resetAndFlush).toBeCalledTimes(1)
+    })
+
+    it('should release the connection', async () => {
+      const { connectionProvider, seenConnections } = setup()
+
+      await connectionProvider.verifyConnectivityAndGetServerInfo()
+
+      expect(seenConnections[0]._release).toHaveBeenCalledTimes(1)
+    })
+
+    it('should resetAndFlush and then release the connection', async () => {
+      const { connectionProvider, seenConnections, resetAndFlush } = setup()
+
+      await connectionProvider.verifyConnectivityAndGetServerInfo()
+
+      expect(seenConnections[0]._release.mock.invocationCallOrder[0])
+        .toBeGreaterThan(resetAndFlush.mock.invocationCallOrder[0])
+    })
+
+    describe('when reset and flush fails', () => {
+      it('should fails with the reset and flush error', async () => {
+        const error = newError('Error')
+        const { connectionProvider, resetAndFlush } = setup()
+
+        resetAndFlush.mockRejectedValue(error)
+
+        try {
+          await connectionProvider.verifyConnectivityAndGetServerInfo()
+          expect().toBe('Not reached')
+        } catch (e) {
+          expect(e).toBe(error)
+        }
+      })
+
+      it('should release the connection', async () => {
+        const error = newError('Error')
+        const { connectionProvider, resetAndFlush, seenConnections } = setup()
+
+        resetAndFlush.mockRejectedValue(error)
+
+        try {
+          await connectionProvider.verifyConnectivityAndGetServerInfo()
+        } catch (e) {
+        } finally {
+          expect(seenConnections[0]._release).toHaveBeenCalledTimes(1)
+        }
+      })
+
+      describe('and release fails', () => {
+        it('should fails with the release error', async () => {
+          const error = newError('Error')
+          const releaseError = newError('release errror')
+
+          const { connectionProvider, resetAndFlush } = setup(
+            {
+              releaseMock: () => Promise.reject(releaseError)
+            })
+
+          resetAndFlush.mockRejectedValue(error)
+
+          try {
+            await connectionProvider.verifyConnectivityAndGetServerInfo()
+            expect().toBe('Not reached')
+          } catch (e) {
+            expect(e).toBe(releaseError)
+          }
+        })
+      })
+    })
+
+    describe('when release fails', () => {
+      it('should fails with the release error', async () => {
+        const error = newError('Error')
+
+        const { connectionProvider } = setup(
+          {
+            releaseMock: () => Promise.reject(error)
+          })
+
+        try {
+          await connectionProvider.verifyConnectivityAndGetServerInfo()
+          expect().toBe('Not reached')
+        } catch (e) {
+          expect(e).toBe(error)
+        }
+      })
+    })
+
+    function setup({ releaseMock } = {}) {
+      const protocolVersion = 4.4
+      const resetAndFlush = jest.fn(() => Promise.resolve())
+      const server = { address: 'localhost:123', version: 'neo4j/1234' }
+      const seenConnections = []
+      const create = (address, release) => {
+        const connection = new FakeConnection(address, release, server)
+        connection.protocol = () => {
+          return { version: protocolVersion }
+        }
+        connection.resetAndFlush = resetAndFlush
+        if (releaseMock) {
+          connection._release = releaseMock
+        }
+        seenConnections.push(connection)
+        return connection
+      }
+      const address = ServerAddress.fromUrl('localhost:123')
+      const pool = newPool({ create })
+      const connectionProvider = newDirectConnectionProvider(address, pool)
+      return {
+        connectionProvider,
+        server,
+        protocolVersion,
+        resetAndFlush,
+        seenConnections
+      }
+    }
+  })
+
+  describe('when connection is not available in the pool', () => {
+    it('should reject with acquisition timeout error', async () => {
+      const address = ServerAddress.fromUrl('localhost:123')
+      const pool = newPool({
+        config: {
+          acquisitionTimeout: 0,
+        }
+      })
+
+      const connectionProvider = newDirectConnectionProvider(address, pool)
+
+      try {
+        connectionProvider = await connectionProvider.verifyConnectivityAndGetServerInfo()
+        expect().toBe('not reached')
+      } catch (e) {
+        expect(e).toBeDefined()
+      }
+    })
+  })
+
+  describe('when connection it could not create the connection', () => {
+    it('should reject with connection creation error', async () => {
+      const error = new Error('Connection creation error')
+      const address = ServerAddress.fromUrl('localhost:123')
+      const pool = newPool({
+        create: () => { throw error }
+      })
+
+      const connectionProvider = newDirectConnectionProvider(address, pool)
+
+      try {
+        connectionProvider = await connectionProvider.verifyConnectivityAndGetServerInfo()
+        expect().toBe('not reached')
+      } catch (e) {
+        expect(e).toBe(error)
+      }
+    })
+  })
+})
+
 function newDirectConnectionProvider (address, pool) {
   const connectionProvider = new DirectConnectionProvider({
     id: 0,
@@ -150,22 +324,34 @@ function newDirectConnectionProvider (address, pool) {
   return connectionProvider
 }
 
-function newPool () {
+function newPool({ create, config } = {}) {
+  const _create = (address, release) => {
+    if (create) {
+      return create(address, release)
+    }
+    return new FakeConnection(address, release)
+  }
   return new Pool({
+    config,
     create: (address, release) =>
-      Promise.resolve(new FakeConnection(address, release))
+      Promise.resolve(_create(address, release)),
   })
 }
 
 class FakeConnection extends Connection {
-  constructor (address, release) {
+  constructor(address, release, server) {
     super(null)
 
     this._address = address
-    this.release = release
+    this._release = jest.fn(() => release(address, this))
+    this._server = server
   }
 
-  get address () {
+  get address() {
     return this._address
   }
+
+  get server() {
+    return this._server
+  }
 }