start listening for file system events before reading from the logfile

tailer/fileTailer.go

@@ -94,6 +94,10 @@ func runFileTailer(path string, readall bool, logger simpleLogger, makeWatcher f
 			writeError(errors, done, "Failed to initialize file system watcher for %v: %v", path, err.Error())
 			return
 		}
+		eventLoop := watcher.StartEventLoop()
+		defer closeUnlessNil(eventLoop)
+
+		// process all pre-existing lines before listening to new events
 		reader := NewBufferedLineReader()
 		freshLines, err := reader.ReadAvailableLines(file)
 		if err != nil {
@@ -108,9 +112,6 @@ func runFileTailer(path string, readall bool, logger simpleLogger, makeWatcher f
 			}
 		}
 
-		eventLoop := watcher.StartEventLoop()
-		defer closeUnlessNil(eventLoop)
-
 		for {
 			select {
 			case <-done:

tailer/fileTailer_test.go

@@ -209,7 +209,7 @@ func testLogrotate(t *testing.T, log simpleLogger, watcherOpt watcherType, logro
 	// the tailer's errorChannel in case something goes wrong.
 	go func() {
 		for err := range tail.Errors() {
-			t.Fatalf("Tailer failed: %v", err.Error())
+			t.Errorf("Tailer failed: %v", err.Error()) // Cannot call t.Fatalf() in other goroutine.
 		}
 	}()
 
@@ -220,7 +220,7 @@ func testLogrotate(t *testing.T, log simpleLogger, watcherOpt watcherType, logro
 
 	// Append a line and see if the event is processed.
 	logFileWriter.writeLine(t, log, "test line 3")
-	expect(t, log, tail.Lines(), "test line 3", 5*time.Second) // test on Travis CI fails sometimes here although the write event is processed correctly. maybe a timing problem? increase to 5s and see if error persists.
+	expect(t, log, tail.Lines(), "test line 3", 1*time.Second)
 
 	rotate(t, log, logfile, logrotateOpt, logrotateMoveOpt)