move logger to core

Author: bigmontz

core/src/internal/index.ts

@@ -26,6 +26,7 @@ import * as connectionHolder from './connection-holder'
 import * as txConfig from './tx-config'
 import * as transactionExecutor from './transaction-executor'
 import * as connectivityVerifier from './connectivity-verifier'
+import * as logger from './logger'
 
 export {
   util,
@@ -36,5 +37,6 @@ export {
   connectionHolder,
   txConfig,
   transactionExecutor,
-  connectivityVerifier
+  connectivityVerifier,
+  logger
 }

core/src/internal/logger.ts

@@ -0,0 +1,231 @@
+/**
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { newError } from '../error'
+
+export type LogLevel = 'warn' | 'error' | 'info' | 'debug'
+type LoggerFunction = (level: LogLevel, message: string) => unknown
+
+interface LoggingConfig {
+  level?: LogLevel
+  logger: LoggerFunction
+}
+
+const ERROR: 'error' = 'error'
+const WARN: 'warn' = 'warn'
+const INFO: 'info' = 'info'
+const DEBUG: 'debug' = 'debug'
+
+const DEFAULT_LEVEL = INFO
+
+const levels = {
+  [ERROR]: 0,
+  [WARN]: 1,
+  [INFO]: 2,
+  [DEBUG]: 3
+}
+
+/**
+ * Logger used by the driver to notify about various internal events. Single logger should be used per driver.
+ */
+export class Logger {
+  private readonly _level: LogLevel
+  private readonly _loggerFunction: LoggerFunction
+  /**
+   * @constructor
+   * @param {string} level the enabled logging level.
+   * @param {function(level: string, message: string)} loggerFunction the function to write the log level and message.
+   */
+  constructor(level: LogLevel, loggerFunction: LoggerFunction) {
+    this._level = level
+    this._loggerFunction = loggerFunction
+  }
+
+  /**
+   * Create a new logger based on the given driver configuration.
+   * @param {Object} driverConfig the driver configuration as supplied by the user.
+   * @return {Logger} a new logger instance or a no-op logger when not configured.
+   */
+  static create(driverConfig: { logging?: LoggingConfig }) {
+    if (driverConfig && driverConfig.logging) {
+      const loggingConfig = driverConfig.logging
+      const level = extractConfiguredLevel(loggingConfig)
+      const loggerFunction = extractConfiguredLogger(loggingConfig)
+      return new Logger(level, loggerFunction)
+    }
+    return this.noOp()
+  }
+
+  /**
+   * Create a no-op logger implementation.
+   * @return {Logger} the no-op logger implementation.
+   */
+  static noOp(): Logger {
+    return noOpLogger
+  }
+
+  /**
+   * Check if error logging is enabled, i.e. it is not a no-op implementation.
+   * @return {boolean} `true` when enabled, `false` otherwise.
+   */
+  isErrorEnabled(): boolean {
+    return isLevelEnabled(this._level, ERROR)
+  }
+
+  /**
+   * Log an error message.
+   * @param {string} message the message to log.
+   */
+  error(message: string) {
+    if (this.isErrorEnabled()) {
+      this._loggerFunction(ERROR, message)
+    }
+  }
+
+  /**
+   * Check if warn logging is enabled, i.e. it is not a no-op implementation.
+   * @return {boolean} `true` when enabled, `false` otherwise.
+   */
+  isWarnEnabled(): boolean {
+    return isLevelEnabled(this._level, WARN)
+  }
+
+  /**
+   * Log an warning message.
+   * @param {string} message the message to log.
+   */
+  warn(message: string) {
+    if (this.isWarnEnabled()) {
+      this._loggerFunction(WARN, message)
+    }
+  }
+
+  /**
+   * Check if info logging is enabled, i.e. it is not a no-op implementation.
+   * @return {boolean} `true` when enabled, `false` otherwise.
+   */
+  isInfoEnabled(): boolean {
+    return isLevelEnabled(this._level, INFO)
+  }
+
+  /**
+   * Log an info message.
+   * @param {string} message the message to log.
+   */
+  info(message: string) {
+    if (this.isInfoEnabled()) {
+      this._loggerFunction(INFO, message)
+    }
+  }
+
+  /**
+   * Check if debug logging is enabled, i.e. it is not a no-op implementation.
+   * @return {boolean} `true` when enabled, `false` otherwise.
+   */
+  isDebugEnabled(): boolean {
+    return isLevelEnabled(this._level, DEBUG)
+  }
+
+  /**
+   * Log a debug message.
+   * @param {string} message the message to log.
+   */
+  debug(message: string) {
+    if (this.isDebugEnabled()) {
+      this._loggerFunction(DEBUG, message)
+    }
+  }
+}
+
+class NoOpLogger extends Logger {
+  constructor() {
+    super(INFO, (level: LogLevel, message: string) => {})
+  }
+
+  isErrorEnabled() {
+    return false
+  }
+
+  error(message: string) {}
+
+  isWarnEnabled() {
+    return false
+  }
+
+  warn(message: string) {}
+
+  isInfoEnabled() {
+    return false
+  }
+
+  info(message: string) {}
+
+  isDebugEnabled() {
+    return false
+  }
+
+  debug(message: string) {}
+}
+
+const noOpLogger = new NoOpLogger()
+
+/**
+ * Check if the given logging level is enabled.
+ * @param {string} configuredLevel the configured level.
+ * @param {string} targetLevel the level to check.
+ * @return {boolean} value of `true` when enabled, `false` otherwise.
+ */
+function isLevelEnabled(configuredLevel: LogLevel, targetLevel: LogLevel) {
+  return levels[configuredLevel] >= levels[targetLevel]
+}
+
+/**
+ * Extract the configured logging level from the driver's logging configuration.
+ * @param {Object} loggingConfig the logging configuration.
+ * @return {string} the configured log level or default when none configured.
+ */
+function extractConfiguredLevel(loggingConfig: LoggingConfig): LogLevel {
+  if (loggingConfig && loggingConfig.level) {
+    const configuredLevel = loggingConfig.level
+    const value = levels[configuredLevel]
+    if (!value && value !== 0) {
+      throw newError(
+        `Illegal logging level: ${configuredLevel}. Supported levels are: ${Object.keys(
+          levels
+        )}`
+      )
+    }
+    return configuredLevel
+  }
+  return DEFAULT_LEVEL
+}
+
+/**
+ * Extract the configured logger function from the driver's logging configuration.
+ * @param {Object} loggingConfig the logging configuration.
+ * @return {function(level: string, message: string)} the configured logging function.
+ */
+function extractConfiguredLogger(loggingConfig: LoggingConfig): LoggerFunction {
+  if (loggingConfig && loggingConfig.logger) {
+    const configuredLogger = loggingConfig.logger
+    if (configuredLogger && typeof configuredLogger === 'function') {
+      return configuredLogger
+    }
+  }
+  throw newError(`Illegal logger function: ${loggingConfig.logger}`)
+}