feat(sut): add worker that works in batches

src/sut/dumblog/src/Dumblog/SQLite/Worker.hs

@@ -2,10 +2,11 @@ module Dumblog.SQLite.Worker where
 
 import Control.Concurrent.MVar (putMVar)
 import Control.Concurrent.STM (atomically)
-import Control.Concurrent.STM.TBQueue (TBQueue, readTBQueue)
+import Control.Concurrent.STM.TBQueue
+       (TBQueue, flushTBQueue, readTBQueue)
 
-import Dumblog.SQLite.DB
 import Dumblog.SQLite.Command
+import Dumblog.SQLite.DB
 
 ------------------------------------------------------------------------
 
@@ -15,11 +16,22 @@ worker queue conn = go
     go :: IO ()
     go = do
       cmd <- atomically (readTBQueue queue)
-      case cmd of
-        Read ix response -> do
-          bs <- readDB conn ix
-          putMVar response bs
-        Write bs response -> do
-          ix <- writeDB conn bs
-          putMVar response ix
+      execute conn cmd
+      go
+
+batchingWorker :: TBQueue Command -> Connection -> IO ()
+batchingWorker queue conn = go
+  where
+    go :: IO ()
+    go = do
+      cmds <- atomically (flushTBQueue queue)
+      mapM_ (execute conn) cmds
       go
+
+execute :: Connection -> Command -> IO ()
+execute conn (Read ix response) = do
+  bs <- readDB conn ix
+  putMVar response bs
+execute conn (Write bs response) = do
+  ix <- writeDB conn bs
+  putMVar response ix