Move Pool module to core (#1212)

The `pool` holds logic on resource pooling and it is used to avoid better resource management, enabling the driver to re-use connections and avoiding overflow server and cluster with too much connections. The pool also regulates acquisition timeouts, this avoiding clients to wait an undetermined amount time for acquiring resource when driver is busy. 

This module is being moved to the core module to enabling drivers developers to re-use this module in context which is not Bolt.

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

@@ -16,8 +16,7 @@
  */
 
 import { createChannelConnection, ConnectionErrorHandler } from '../connection'
-import Pool, { PoolConfig } from '../pool'
-import { error, ConnectionProvider, ServerInfo, newError } from 'neo4j-driver-core'
+import { error, ConnectionProvider, ServerInfo, newError, internal } from 'neo4j-driver-core'
 import AuthenticationProvider from './authentication-provider'
 import { object } from '../lang'
 import LivenessCheckProvider from './liveness-check-provider'
@@ -31,6 +30,12 @@ const AUTHENTICATION_ERRORS = [
   'Neo.ClientError.Security.Unauthorized'
 ]
 
+const {
+  pool: {
+    Pool, PoolConfig
+  }
+} = internal
+
 export default class PooledConnectionProvider extends ConnectionProvider {
   constructor (
     { id, config, log, userAgent, boltAgent, authTokenManager, newPool = (...args) => new Pool(...args) },

packages/bolt-connection/src/index.js

@@ -20,6 +20,5 @@ export * as bolt from './bolt'
 export * as buf from './buf'
 export * as channel from './channel'
 export * as packstream from './packstream'
-export * as pool from './pool'
 
 export * from './connection-provider'

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

@@ -16,7 +16,6 @@
  */
 
 import DirectConnectionProvider from '../../src/connection-provider/connection-provider-direct'
-import { Pool } from '../../src/pool'
 import { Connection, DelegateConnection } from '../../src/connection'
 import { authTokenManagers, internal, newError, ServerInfo, staticAuthTokenManager } from 'neo4j-driver-core'
 import AuthenticationProvider from '../../src/connection-provider/authentication-provider'
@@ -25,7 +24,8 @@ import LivenessCheckProvider from '../../src/connection-provider/liveness-check-
 
 const {
   serverAddress: { ServerAddress },
-  logger: { Logger }
+  logger: { Logger },
+  pool: { Pool }
 } = internal
 
 describe('#unit DirectConnectionProvider', () => {

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

@@ -27,7 +27,6 @@ import {
   authTokenManagers
 } from 'neo4j-driver-core'
 import { RoutingTable } from '../../src/rediscovery/'
-import { Pool } from '../../src/pool'
 import SimpleHostNameResolver from '../../src/channel/browser/browser-host-name-resolver'
 import RoutingConnectionProvider from '../../src/connection-provider/connection-provider-routing'
 import { DelegateConnection, Connection } from '../../src/connection'
@@ -37,7 +36,8 @@ import LivenessCheckProvider from '../../src/connection-provider/liveness-check-
 
 const {
   serverAddress: { ServerAddress },
-  logger: { Logger }
+  logger: { Logger },
+  pool: { Pool }
 } = internal
 
 const { SERVICE_UNAVAILABLE, SESSION_EXPIRED } = error

packages/core/src/internal/index.ts

@@ -29,6 +29,7 @@ import * as serverAddress from './server-address'
 import * as resolver from './resolver'
 import * as objectUtil from './object-util'
 import * as boltAgent from './bolt-agent/index'
+import * as pool from './pool'
 
 export {
   util,
@@ -44,5 +45,6 @@ export {
   serverAddress,
   resolver,
   objectUtil,
-  boltAgent
+  boltAgent,
+  pool
 }

packages/bolt-connection/src/pool/pool-config.js → packages/core/src/internal/pool/pool-config.ts

@@ -19,40 +19,42 @@ const DEFAULT_MAX_SIZE = 100
 const DEFAULT_ACQUISITION_TIMEOUT = 60 * 1000 // 60 seconds
 
 export default class PoolConfig {
-  constructor (maxSize, acquisitionTimeout) {
+  public readonly maxSize: number
+  public readonly acquisitionTimeout: number
+
+  constructor (maxSize: number, acquisitionTimeout: number) {
     this.maxSize = valueOrDefault(maxSize, DEFAULT_MAX_SIZE)
     this.acquisitionTimeout = valueOrDefault(
       acquisitionTimeout,
       DEFAULT_ACQUISITION_TIMEOUT
     )
   }
 
-  static defaultConfig () {
+  static defaultConfig (): PoolConfig {
     return new PoolConfig(DEFAULT_MAX_SIZE, DEFAULT_ACQUISITION_TIMEOUT)
   }
 
-  static fromDriverConfig (config) {
-    const maxSizeConfigured = isConfigured(config.maxConnectionPoolSize)
-    const maxSize = maxSizeConfigured
+  static fromDriverConfig (config: { maxConnectionPoolSize?: number, connectionAcquisitionTimeout?: number }): PoolConfig {
+    const maxSize = isConfigured(config.maxConnectionPoolSize)
       ? config.maxConnectionPoolSize
       : DEFAULT_MAX_SIZE
-    const acquisitionTimeoutConfigured = isConfigured(
+
+    const acquisitionTimeout = isConfigured(
       config.connectionAcquisitionTimeout
     )
-    const acquisitionTimeout = acquisitionTimeoutConfigured
       ? config.connectionAcquisitionTimeout
       : DEFAULT_ACQUISITION_TIMEOUT
 
     return new PoolConfig(maxSize, acquisitionTimeout)
   }
 }
 
-function valueOrDefault (value, defaultValue) {
-  return value === 0 || value ? value : defaultValue
+function valueOrDefault (value: number | undefined, defaultValue: number): number {
+  return isConfigured(value) ? value : defaultValue
 }
 
-function isConfigured (value) {
-  return value === 0 || value
+function isConfigured (value?: number): value is number {
+  return value === 0 || value != null
 }
 
 export { DEFAULT_MAX_SIZE, DEFAULT_ACQUISITION_TIMEOUT }