Attempt at fixing the issues with ExceptionHandler in #1289 (#1355)

lib/winston/exception-handler.js

@@ -201,8 +201,6 @@ module.exports = class ExceptionHandler {
 
     // Log to all transports attempting to listen for when they are completed.
     asyncForEach(handlers, (handler, next) => {
-      // TODO: Change these to the correct WritableStream events so that we
-      // wait until exit.
       const done = once(next);
       const transport = handler.transport || handler;
 
@@ -214,9 +212,10 @@ module.exports = class ExceptionHandler {
         };
       }
 
-      transport.once('logged', onDone('logged'));
+      transport._ending = true;
+      transport.once('finish', onDone('finished'));
       transport.once('error', onDone('error'));
-    }, gracefulExit);
+    }, () => doExit && gracefulExit());
 
     this.logger.log(info);
 

lib/winston/transports/file.js

@@ -86,10 +86,26 @@ module.exports = class File extends TransportStream {
     this._created = 0;
     this._drain = false;
     this._opening = false;
+    this._ending = false;
 
     this.open();
   }
 
+  finishIfEnding() {
+    if (this._ending) {
+      if (this._opening) {
+        this.once('open', () => {
+          this._stream.once('finish', () => this.emit('finish'));
+          setImmediate(() => this._stream.end());
+        });
+      } else {
+        this._stream.once('finish', () => this.emit('finish'));
+        setImmediate(() => this._stream.end());
+      }
+    }
+  }
+
+
   /**
    * Core logging method exposed to Winston. Metadata is optional.
    * @param {Object} info - TODO: add param description.
@@ -177,6 +193,8 @@ module.exports = class File extends TransportStream {
 
     debug('written', written, this._drain);
 
+    this.finishIfEnding();
+
     return written;
   }
 
@@ -503,12 +521,16 @@ module.exports = class File extends TransportStream {
    * @param {function} callback - Callback for when the current file has closed.
    * @private
    */
-  _endStream(callback) {
-    this._stream.unpipe(this._dest);
-    this._dest.end(() => {
-      this._cleanupStream(this._dest);
-      callback();
-    });
+  _endStream(callback = () => {}) {
+    if (this._dest) {
+      this._stream.unpipe(this._dest);
+      this._dest.end(() => {
+        this._cleanupStream(this._dest);
+        callback();
+      });
+    } else {
+      callback(); // eslint-disable-line callback-return
+    }
   }
 
   /**