loganalysis/lib/console_config.js

Collects stdout and stderr messages from Node.js applications and sends them to the IBM SmartCloud Analytics - Log Analysis service.

/*
 * © Copyright IBM Corp. 2014
 *
 * 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.
 */

var scala = require('./scala');

var logger = require('./logger').newLogger('console_config');

const INFO_LEVEL = 'I';

const ERROR_LEVEL = 'E';

function ConsoleAutoConfig() {
  this.nativeStderrWrite = process.stderr.write;
  this.nativeStdoutWrite = process.stdout.write;
  this.scalaClients = scala.createCloudAwareScalaClients();
  this.initialized = false;
}

ConsoleAutoConfig.prototype.setUp = function () {
  //Use initialized flag to avoid duplicated setUp invocation
  if (this.initialized) {
    return;
  }

  var scalaClients = this.scalaClients;

  if (scalaClients.length == 0) {
    logger.debug('No scala clients is detected, skip the console auto-config initialization');
    return;
  }

  if (!this.nativeStdoutWrite) {
    this.nativeStdoutWrite = process.stdout.write;
  }
  var oldStdoutWrite = this.nativeStdoutWrite;
  process.stdout.write = function () {
    if (arguments.length >= 1) {
      for (var i = 0, length = scalaClients.length; i < length; i++) {
        scalaClients[i].emit(arguments[0], INFO_LEVEL);
      }
      oldStdoutWrite.apply(process.stdout, arguments);
    }
  };

  logger.debug('process.stdout.write is overriden');

  if (!this.nativeStderrWrite) {
    this.nativeStderrWrite = process.stderr.write;
  }
  var oldStderrWrite = this.nativeStderrWrite;
  process.stderr.write = function () {
    if (arguments.length >= 1) {
      for (var i = 0, length = scalaClients.length; i < length; i++) {
        scalaClients[i].emit(arguments[0], ERROR_LEVEL);
      }
    }
    oldStderrWrite.apply(process.stderr, arguments);
  };
  logger.debug('process.stderr.write is overriden');

  logger.info('Initialization SUCCESS');
  this.initialized = true;
};

ConsoleAutoConfig.prototype.cleanUp = function () {
  logger.debug('Entering ConsoleAutoConfig.prototype.cleanUp');
  if (!this.initialized) {
    return;
  }
  if (this.nativeStdoutWrite) {
    process.stdout.write = this.nativeStdoutWrite;
    this.nativeStdoutWrite= null;
  }
  if (this.nativeStderrWrite) {
    process.stderr.write = this.nativeStderrWrite;
    this.nativeStderrWrite = null;
  }
  for (var i = 0, length = this.scalaClients.length; i < length; i++) {
    this.scalaClients[i].cleanUp();
  }
  this.initialized = false;
  logger.debug('Exiting ConsoleAutoConfig.prototype.cleanUp');
};

ConsoleAutoConfig.prototype.getNativeStdoutWrite = function () {
  return this.nativeStdoutWrite;
};

ConsoleAutoConfig.prototype.getNativeStderrWrite = function () {
  return this.nativeStderrWrite;
};

ConsoleAutoConfig.prototype.getActiveScalaClients = function () {
  return this.scalaClients;
};

ConsoleAutoConfig.prototype.addScalaClient = function(scalaClient) {
  logger.debug('Entering ConsoleAutoConfig.prototype.addScalaClient');
  for (var i = 0, length = this.scalaClients.length; i < length; i++) {
    if(this.scalaClients[i] === scalaClient) {
      return;
    }
  }
  this.scalaClients.push(scalaClient);
  if(!this.initialized) {
    logger.debug('One scala client is added, will set up the console auto-config');
    this.setUp();
  }
  logger.debug('Exiting ConsoleAutoConfig.prototype.addScalaClient');
};

ConsoleAutoConfig.prototype.removeScalaClient = function(scalaClient) {
  logger.debug('Entering ConsoleAutoConfig.prototype.removeScalaClient');
  for (var i = 0, length = this.scalaClients.length; i < length; i++) {
    if(this.scalaClients[i] === scalaClient) {
      this.scalaClients.splice(i, 1);
      break;
    }
  }
  if(this.scalaClients.length == 0 && this.initialized) {
    logger.debug('No scala clients found, will clean up the console auto-config');
    this.cleanUp();
  }
  logger.debug('Exiting ConsoleAutoConfig.prototype.removeScalaClient');
};

var consoleAutoConfig = new ConsoleAutoConfig();
module.exports = consoleAutoConfig;