A few more fixes for better compatibility with the latest mongodb.

Keep connection as long as there is a stream of logs. Close on inactivity.

lib/winston-mongodb.js

@@ -31,18 +31,17 @@ var MongoDB = exports.MongoDB = function (options) {
   this.silent = options.silent || false;
   this.username = options.username || null;
   this.password = options.password || null;
-  this.timeout = options.timeout || 10000;
-  if (!(options.keepAlive === true)) {
-    this.keepAlive = false;
-    if (!options.timeout && options.keepAlive) {
-      // Backward compatibility for setting timeout via keepAlive.
-      this.timeout = options.keepAlive;
-    }
+  this.errortimeout = options.errortimeout || 10000;
+  if (options.keepAlive !== true) {
+    // Backward compatibility for timeout delivered in keepAlive parameter.
+    this.timeout = options.timeout || options.keepAlive || 10000;
   }
   this.state = 'unopened';
+  this.timeoutId = null;
   this.pending = [];
 
-  this.client = new mongodb.Db(this.db, new mongodb.Server(this.host, this.port, {}), {
+  this.server = new mongodb.Server(this.host, this.port, {});
+  this.client = new mongodb.Db(this.db, this.server, {
     native_parser: false
   });
 };
@@ -69,42 +68,68 @@ winston.transports.MongoDB = MongoDB;
 MongoDB.prototype.log = function (level, msg, meta, callback) {
   var self = this;
 
-  if (this.silent) {
-    return callback(null, true);
-  }
+  // Avoid reentrancy that can be not assumed by database code.
+  // If database logs, better not to call database itself in the same call.
+  process.nextTick(function () {
 
-  this.open(function (err) {
-    if (err) {
-      self.emit('error', err);
-      return callback(err, null);
+    if (self.silent) {
+      return callback(null, true);
     }
 
-    self._db.collection(self.collection, function (err, col) {
+    self.open(function (err) {
       if (err) {
         self.emit('error', err);
         return callback(err, null);
       }
 
-      var entry = {
-        timestamp: new Date(), // RFC3339/ISO8601 format instead of common.timestamp()
-        level: level,
-        message: msg,
-        meta: meta
-      };
-
-      col.save(entry, { safe: self.safe }, function (err, doc) {
+      self._db.collection(self.collection, function (err, col) {
         if (err) {
           self.emit('error', err);
           return callback(err, null);
         }
 
-        self.emit('logged');
-        return callback(null, true);
+        var entry = {
+          timestamp: new Date(), // RFC3339/ISO8601 format instead of common.timestamp()
+          level: level,
+          message: msg,
+          meta: meta
+        };
+
+        col.save(entry, { safe: self.safe }, function (err, doc) {
+          if (err) {
+            self.emit('error', err);
+            return callback(err, null);
+          }
+
+          self.emit('logged');
+          // Delay timeout to start from the last successful log.
+          self.setTimeout();
+          return callback(null, true);
+        });
       });
     });
   });
 };
 
+MongoDB.prototype.setTimeout = function () {
+  var self = this;
+  if (!self.timeout) {
+    return;
+  }
+  if (self.timeoutId) {
+    clearTimeout(self.timeoutId);
+  }
+  //
+  // Set a timeout to close the client connection unless `self.keepAlive`
+  // has been set to true in which case it is the responsibility of the
+  // programmer to close the underlying connection.
+  //
+  self.timeoutId = setTimeout(function () {
+    self.client.close();
+    self.state = 'unopened';
+  }, self.timeout);
+}
+
 //
 // ### function open (callback)
 // #### @callback {function} Continuation to respond to when complete
@@ -114,25 +139,25 @@ MongoDB.prototype.log = function (level, msg, meta, callback) {
 MongoDB.prototype.open = function (callback) {
   var self = this;
 
-  if (this.state === 'opening' || this.state === 'unopened') {
+  if (self.state === 'opening' || self.state === 'unopened') {
     //
     // While opening our MongoDB connection, append any callback
     // to a list that is managed by this instance.
     //
-    this.pending.push(callback);
+    self.pending.push(callback);
 
-    if (this.state === 'opening') {
+    if (self.state === 'opening') {
       return;
     }
   }
-  else if (this.state === 'opened') {
+  else if (self.state === 'opened') {
     return callback();
   }
-  else if (this.state === 'error') {
+  else if (self.state === 'error') {
     return callback(self.error);
   }
 
-  function completion(err) {
+  function flushCallbacks(err) {
     //
     // Iterate over all callbacks that have accumulated during
     // the creation of the TCP socket.
@@ -143,37 +168,29 @@ MongoDB.prototype.open = function (callback) {
 
     // Quickly truncate the Array (this is more performant).
     self.pending.length = 0;
-
-    //
-    // Set a timeout to close the client connection unless `self.keepAlive`
-    // has been set to true in which case it is the responsibility of the
-    // programmer to close the underlying connection.
-    //
-    if (!self.keepAlive || err) {
-      setTimeout(function () {
-        self.state = 'unopened';
-        if (self._db) {
-          // Connection was opened.
-          self._db.close();
-        }
-      }, self.timeout);
-    }
   }
 
   function onError(err) {
     self.state = 'error';
     self.error = err;
-    completion(err);
+    flushCallbacks(err);
+    // Close to be able to attempt opening later.
+    self.client.close();
+    // Retry new connection upon following request after error timeout expired.
+    setTimeout(function () {
+      self.state = 'unopened';
+    }, self.errortimeout);
   }
 
   function onSuccess(db) {
     self.state = 'opened';
     self._db = db;
-    completion();
+    flushCallbacks();
+    self.setTimeout();
   }
 
-  this.state = 'opening';
-  this.client.open(function (err, db) {
+  self.state = 'opening';
+  self.client.open(function (err, db) {
     if (err) {
       return onError(err);
     }