Merge pull request #149 from mkielar/master

Clustered appender for log4js.

lib/appenders/clustered.js

@@ -0,0 +1,118 @@
+"use strict";
+
+var cluster = require('cluster');
+var log4js = require('../log4js');
+
+/**
+ * Takes a loggingEvent object, returns string representation of it.
+ */
+function serializeLoggingEvent(loggingEvent) {
+	return JSON.stringify(loggingEvent);
+}
+
+/**
+ * Takes a string, returns an object with
+ * the correct log properties.
+ *
+ * This method has been "borrowed" from the `multiprocess` appender 
+ * by `nomiddlename` (https://github.com/nomiddlename/log4js-node/blob/master/lib/appenders/multiprocess.js)
+ *
+ * Apparently, node.js serializes everything to strings when using `process.send()`, 
+ * so we need smart deserialization that will recreate log date and level for further processing by log4js internals.
+ */
+function deserializeLoggingEvent(loggingEventString) {
+
+	var loggingEvent;
+	
+	try {
+	
+		loggingEvent = JSON.parse(loggingEventString);
+		loggingEvent.startTime = new Date(loggingEvent.startTime);
+		loggingEvent.level = log4js.levels.toLevel(loggingEvent.level.levelStr);
+		
+	} catch (e) {
+		
+		// JSON.parse failed, just log the contents probably a naughty.
+		loggingEvent = {
+			startTime: new Date(),
+			categoryName: 'log4js',
+			level: log4js.levels.ERROR,
+			data: [ 'Unable to parse log:', loggingEventString ]
+		};
+	}
+	return loggingEvent;
+} 
+
+/**
+ * Creates an appender. 
+ *
+ * If the current process is a master (`cluster.isMaster`), then this will be a "master appender".
+ * Otherwise this will be a worker appender, that just sends loggingEvents to the master process.
+ *
+ * If you are using this method directly, make sure to provide it with `config.actualAppenders` array 
+ * of actual appender instances.
+ *
+ * Or better use `configure(config, options)`
+ */
+function createAppender(config) {
+
+	if (cluster.isMaster) {
+
+		var masterAppender = function(loggingEvent) {
+	
+			if (config.actualAppenders) {
+				var size = config.actualAppenders.length;
+				for(var i = 0; i < size; i++) {
+					config.actualAppenders[i](loggingEvent);
+				}
+			}
+		}
+		
+		// Listen on new workers
+		cluster.on('fork', function(worker) {
+		
+			worker.on('message', function(message) {
+				if (message.type && message.type === '::log-message') {
+					// console.log("master : " + cluster.isMaster + " received message: " + JSON.stringify(message.event));
+					
+					var loggingEvent = deserializeLoggingEvent(message.event);
+					masterAppender(loggingEvent);
+				}
+			});
+		
+		});
+		
+		return masterAppender;
+		
+	} else {
+
+		return function(loggingEvent) {
+			// If inside the worker process, then send the logger event to master.
+			if (cluster.isWorker) {
+				// console.log("worker " + cluster.worker.id + " is sending message");
+				process.send({ type: '::log-message', event: serializeLoggingEvent(loggingEvent)});
+			}
+		}
+	}
+}
+
+function configure(config, options) {
+
+	if (config.appenders && cluster.isMaster) {
+	
+		var size = config.appenders.length;
+		config.actualAppenders = new Array(size);
+	
+		for(var i = 0; i < size; i++) {
+		
+			log4js.loadAppender(config.appenders[i].type);
+			config.actualAppenders[i] = log4js.appenderMakers[config.appenders[i].type](config.appenders[i], options);
+		
+		}
+	}
+	
+	return createAppender(config);
+}
+
+exports.appender = createAppender;
+exports.configure = configure; 

test/clusteredAppender-test.js

@@ -0,0 +1,116 @@
+"use strict";
+var assert = require('assert');
+var vows = require('vows');
+var layouts = require('../lib/layouts');
+var sandbox = require('sandboxed-module');
+var LoggingEvent = require('../lib/logger').LoggingEvent;
+var cluster = require('cluster');
+
+vows.describe('log4js cluster appender').addBatch({
+	'when in master mode': {
+		topic: function() {
+
+			var registeredClusterEvents = [];
+			var loggingEvents = [];
+			
+			// Fake cluster module, so no cluster listeners be really added 
+			var fakeCluster = {
+			
+				on: function(event, callback) {
+					registeredClusterEvents.push(event);
+				},
+				
+				isMaster: true,
+				isWorker: false,
+				
+			};
+		
+			var fakeActualAppender = function(loggingEvent) {
+				loggingEvents.push(loggingEvent);
+			}
+			
+			// Load appender and fake modules in it
+			var appenderModule = sandbox.require('../lib/appenders/clustered', {
+				requires: {
+					'cluster': fakeCluster,
+				}
+			});
+		
+			var masterAppender = appenderModule.appender({
+				actualAppenders: [ fakeActualAppender ]
+			});
+
+			// Actual test - log message using masterAppender
+			masterAppender(new LoggingEvent('wovs', 'Info', ['masterAppender test']));
+			
+			var returnValue = {
+				registeredClusterEvents: registeredClusterEvents,
+				loggingEvents: loggingEvents,
+			};
+		
+			return returnValue;
+		}, 
+		
+		"should register 'fork' event listener on 'cluster'": function(topic) { 
+			assert.equal(topic.registeredClusterEvents[0], 'fork');
+		},
+		
+		"should log using actual appender": function(topic) {
+			assert.equal(topic.loggingEvents[0].data[0], 'masterAppender test');
+		},
+		
+	},
+	
+	'when in worker mode': {
+		
+		topic: function() {
+			
+			var registeredProcessEvents = [];
+			
+			// Fake cluster module, to fake we're inside a worker process
+			var fakeCluster = {
+			
+				isMaster: false,
+				isWorker: true,
+				
+			};
+			
+			var fakeProcess = {
+			
+				send: function(data) {
+					registeredProcessEvents.push(data);
+				},
+				
+			};
+			
+			// Load appender and fake modules in it
+			var appenderModule = sandbox.require('../lib/appenders/clustered', {
+				requires: {
+					'cluster': fakeCluster,
+				},
+				globals: {
+					'process': fakeProcess,
+				}
+			});
+			
+			var workerAppender = appenderModule.appender();
+
+			// Actual test - log message using masterAppender
+			workerAppender(new LoggingEvent('wovs', 'Info', ['workerAppender test']));
+			
+			var returnValue = {
+				registeredProcessEvents: registeredProcessEvents,
+			};
+			
+			return returnValue;
+		
+		},
+		
+		"worker appender should call process.send" : function(topic) {
+			assert.equal(topic.registeredProcessEvents[0].type, '::log-message');
+			assert.equal(JSON.parse(topic.registeredProcessEvents[0].event).data[0], "workerAppender test");
+		}
+		
+	}
+
+}).exportTo(module);