Review changes

tensorflow-logging/src/TensorFlow/Logging.hs

@@ -89,18 +89,19 @@ withEventWriter ::
     -- ^ logdir. Directory where event file will be written.
     -> (EventWriter -> m a)
     -> m a
-withEventWriter filePrefix =
-    bracket (liftIO (newEventWriter filePrefix)) (liftIO . closeEventWriter)
+withEventWriter logdir =
+    bracket (liftIO (newEventWriter logdir)) (liftIO . closeEventWriter)
 
 newEventWriter :: FilePath -> IO EventWriter
 newEventWriter logdir = do
     createDirectoryIfMissing True logdir
-    -- Create unique filename from prefix.
     t <- doubleWallTime
     hostname <- getHostName
     let filename = printf (logdir </> "events.out.tfevents.%010d.%s")
                           (truncate t :: Integer) hostname
     -- Asynchronously consume events from a queue.
+    -- We use a bounded queue to ensure the producer doesn't get too far ahead
+    -- of the consumer. The buffer size was picked arbitrarily.
     q <- newTBMQueueIO 1024
     -- Use an MVar to signal that the worker thread has completed.
     done <- newEmptyMVar

tensorflow-logging/tests/LoggingTest.hs

@@ -50,9 +50,10 @@ testEventWriter = testCase "EventWriter" $
         withEventWriter dir $ \eventWriter ->
             mapM_ (logEvent eventWriter) expected
         files <- listDirectory dir
-        assertBool "One file exists after" (length files == 1)
+        assertEqual "One file exists after" 1 (length files)
         records <- runResourceT $ Conduit.runConduit $
             sourceTFRecords (dir </> head files) =$= Conduit.consume
+        assertBool "File is not empty" (not (null records))
         let (header:body) = decodeMessageOrDie . BL.toStrict <$> records
         assertEqual "Header has expected version"
                     (T.pack "brain.Event:2") (header ^. fileVersion)