Revert "servlet: fix write when not ready in AsyncServletOutputStreamWriter

servlet/src/main/java/io/grpc/servlet/AsyncServletOutputStreamWriter.java

@@ -218,15 +218,7 @@ private void assureReadyAndDrainedTurnsFalse() {
   private void runOrBuffer(ActionItem actionItem) throws IOException {
     WriteState curState = writeState.get();
     if (curState.readyAndDrained) { // write to the outputStream directly
-      try {
-        actionItem.run();
-      } catch (IllegalStateException e) {
-        if (actionItem == flushAction || actionItem == completeAction) {
-          throw e;
-        }
-        buffer(actionItem, curState);
-        return;
-      }
+      actionItem.run();
       if (actionItem == completeAction) {
         return;
       }
@@ -238,26 +230,20 @@ private void runOrBuffer(ActionItem actionItem) throws IOException {
         log.finest("the servlet output stream becomes not ready");
       }
     } else { // buffer to the writeChain
-      buffer(actionItem, curState);
+      writeChain.offer(actionItem);
+      if (!writeState.compareAndSet(curState, curState.withReadyAndDrained(false))) {
+        checkState(
+            writeState.get().readyAndDrained,
+            "Bug: onWritePossible() should have changed readyAndDrained to true, but not");
+        ActionItem lastItem = writeChain.poll();
+        if (lastItem != null) {
+          checkState(lastItem == actionItem, "Bug: lastItem != actionItem");
+          runOrBuffer(lastItem);
+        }
+      } // state has not changed since
     }
   }
 
-  private void buffer(ActionItem actionItem, WriteState curState) throws IOException {
-    writeChain.offer(actionItem);
-    if (writeState.compareAndSet(curState, curState.withReadyAndDrained(false))) {
-      LockSupport.unpark(parkingThread);
-    } else {
-      checkState(
-          writeState.get().readyAndDrained,
-          "Bug: onWritePossible() should have changed readyAndDrained to true, but not");
-      ActionItem lastItem = writeChain.poll();
-      if (lastItem != null) {
-        checkState(lastItem == actionItem, "Bug: lastItem != actionItem");
-        runOrBuffer(lastItem);
-      }
-    } // state has not changed since
-  }
-
   /** Write actions, e.g. writeBytes, flush, complete. */
   @FunctionalInterface
   @VisibleForTesting