From 7a6edb5cc467accd3db1ab6f9c78a956a783b352 Mon Sep 17 00:00:00 2001
From: Jianfeng Mao <4297243+jmao-denver@users.noreply.github.com>
Date: Tue, 12 Mar 2024 23:51:43 +0800
Subject: [PATCH] Check for empty data for add/delete/+async (#5242)

---
 .../impl/util/BaseArrayBackedInputTable.java  | 26 ++++++++++++++++---
 py/server/tests/test_table_factory.py         | 20 ++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/engine/table/src/main/java/io/deephaven/engine/table/impl/util/BaseArrayBackedInputTable.java b/engine/table/src/main/java/io/deephaven/engine/table/impl/util/BaseArrayBackedInputTable.java
index 90ac938415e..081a70671fe 100644
--- a/engine/table/src/main/java/io/deephaven/engine/table/impl/util/BaseArrayBackedInputTable.java
+++ b/engine/table/src/main/java/io/deephaven/engine/table/impl/util/BaseArrayBackedInputTable.java
@@ -198,7 +198,9 @@ public TableDefinition getTableDefinition() {
         public void add(@NotNull final Table newData) throws IOException {
             checkBlockingEditSafety();
             PendingChange pendingChange = enqueueAddition(newData);
-            blockingContinuation(pendingChange);
+            if (pendingChange != null) {
+                blockingContinuation(pendingChange);
+            }
         }
 
         @Override
@@ -207,7 +209,11 @@ public void addAsync(
                 @NotNull final InputTableStatusListener listener) {
             checkAsyncEditSafety(newData);
             final PendingChange pendingChange = enqueueAddition(newData);
-            asynchronousContinuation(pendingChange, listener);
+            if (pendingChange != null) {
+                asynchronousContinuation(pendingChange, listener);
+            } else {
+                listener.onSuccess();
+            }
         }
 
         private PendingChange enqueueAddition(@NotNull final Table newData) {
@@ -215,6 +221,9 @@ private PendingChange enqueueAddition(@NotNull final Table newData) {
             // we want to get a clean copy of the table; that can not change out from under us or result in long reads
             // during our UGP run
             final Table newDataSnapshot = snapshotData(newData);
+            if (newDataSnapshot.size() == 0) {
+                return null;
+            }
             final PendingChange pendingChange;
             synchronized (pendingChanges) {
                 pendingChange = new PendingChange(newDataSnapshot, false);
@@ -228,7 +237,9 @@ private PendingChange enqueueAddition(@NotNull final Table newData) {
         public void delete(@NotNull final Table table) throws IOException {
             checkBlockingEditSafety();
             final PendingChange pendingChange = enqueueDeletion(table);
-            blockingContinuation(pendingChange);
+            if (pendingChange != null) {
+                blockingContinuation(pendingChange);
+            }
         }
 
         @Override
@@ -237,12 +248,19 @@ public void deleteAsync(
                 @NotNull final InputTableStatusListener listener) {
             checkAsyncEditSafety(table);
             final PendingChange pendingChange = enqueueDeletion(table);
-            asynchronousContinuation(pendingChange, listener);
+            if (pendingChange != null) {
+                asynchronousContinuation(pendingChange, listener);
+            } else {
+                listener.onSuccess();
+            }
         }
 
         private PendingChange enqueueDeletion(@NotNull final Table table) {
             validateDelete(table);
             final Table oldDataSnapshot = snapshotData(table);
+            if (oldDataSnapshot.size() == 0) {
+                return null;
+            }
             final PendingChange pendingChange;
             synchronized (pendingChanges) {
                 pendingChange = new PendingChange(oldDataSnapshot, true);
diff --git a/py/server/tests/test_table_factory.py b/py/server/tests/test_table_factory.py
index 3045f5bae6a..5ac61b24e36 100644
--- a/py/server/tests/test_table_factory.py
+++ b/py/server/tests/test_table_factory.py
@@ -419,6 +419,26 @@ def test_instant_array(self):
         self.wait_ticking_table_update(t5, row_count=1, timeout=5)
         self.assertEqual(t5.size, 1)
 
+    def test_input_table_empty_data(self):
+        from deephaven import update_graph as ugp
+        from deephaven import execution_context as ec
+
+        ug = ec.get_exec_ctx().update_graph
+        cm = ugp.exclusive_lock(ug)
+
+        with cm:
+            t = time_table("PT1s", blink_table=True)
+            it = input_table({c.name: c.data_type for c in t.columns}, key_cols="Timestamp")
+            it.add(t)
+            self.assertEqual(it.size, 0)
+            it.delete(t)
+            self.assertEqual(it.size, 0)
+
+        t = empty_table(0).update("Timestamp=nowSystem()")
+        it.add(t)
+        self.assertEqual(it.size, 0)
+        it.delete(t)
+        self.assertEqual(it.size, 0)
 
 if __name__ == '__main__':
     unittest.main()