fix: Ensure Flight SQL acquires shared lock

extensions/flight-sql/src/main/java/io/deephaven/server/flightsql/FlightSqlResolver.java

@@ -99,6 +99,7 @@
 import java.util.Objects;
 import java.util.PrimitiveIterator;
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
@@ -644,11 +645,16 @@ interface TicketHandlerReleasable extends TicketHandler {
 
     private Table executeSqlQuery(SessionState session, String sql) {
         // See SQLTODO(catalog-reader-implementation)
-        final QueryScope queryScope = ExecutionContext.getContext().getQueryScope();
+        final ExecutionContext executionContext = ExecutionContext.getContext();
+        final QueryScope queryScope = executionContext.getQueryScope();
         // noinspection unchecked,rawtypes
         final Map<String, Table> queryScopeTables =
                 (Map<String, Table>) (Map) queryScope.toMap(queryScope::unwrapObject, (n, t) -> t instanceof Table);
         final TableSpec tableSpec = Sql.parseSql(sql, queryScopeTables, TicketTable::fromQueryScopeField, null);
+        // Note: we only technically need the lock if any of the source tables are refreshing, but that requires some
+        // deeper introspection. We will play it safe and take the shared lock regardless.
+        final Lock sharedLock = executionContext.getUpdateGraph().sharedLock();
+        sharedLock.lock();
         // Note: this is doing io.deephaven.server.session.TicketResolver.Authorization.transform, but not
         // io.deephaven.auth.ServiceAuthWiring
         // TODO(deephaven-core#6307): Declarative server-side table execution logic that preserves authorization logic
@@ -659,6 +665,8 @@ private Table executeSqlQuery(SessionState session, String sql) {
                 table.retainReference();
             }
             return table;
+        } finally {
+            sharedLock.unlock();
         }
     }
 

extensions/flight-sql/src/test/java/io/deephaven/server/flightsql/FlightSqlTest.java

@@ -11,6 +11,7 @@
 import dagger.Component;
 import dagger.Module;
 import io.deephaven.engine.context.ExecutionContext;
+import io.deephaven.engine.context.QueryScope;
 import io.deephaven.engine.table.ColumnDefinition;
 import io.deephaven.engine.table.Table;
 import io.deephaven.engine.table.TableDefinition;
@@ -86,6 +87,8 @@
 import javax.inject.Singleton;
 import java.io.PrintStream;
 import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.Iterator;
@@ -893,6 +896,55 @@ public void unknownAction() {
         actionNoResolver(() -> doAction(action), type);
     }
 
+    @Test
+    public void refreshingTableTest() throws Exception {
+        // Set a start time so we can test we get out the expected number of rows
+        final Instant startTime = Instant.now().minus(Duration.ofHours(1));
+        final Table tt1 = TableTools.timeTableBuilder()
+                .startTime(startTime)
+                .period(Duration.ofSeconds(1))
+                .build()
+                .view("Timestamp1=Timestamp", "Id=ii % 11")
+                .lastBy("Id");
+        final Table tt2 = TableTools.timeTableBuilder()
+                .startTime(startTime)
+                .period(Duration.ofSeconds(5))
+                .build()
+                .view("Timestamp2=Timestamp", "Id=ii % 11")
+                .lastBy("Id");
+        final QueryScope queryScope = ExecutionContext.getContext().getQueryScope();
+        queryScope.putParam("my_table_1", tt1);
+        queryScope.putParam("my_table_2", tt2);
+        try {
+            final String query = "SELECT\n" +
+                    "  my_table_1.Id,\n" +
+                    "  my_table_1.Timestamp1,\n" +
+                    "  my_table_2.Timestamp2\n" +
+                    "FROM\n" +
+                    "  my_table_1\n" +
+                    "  INNER JOIN my_table_2 ON my_table_1.Id = my_table_2.Id";
+            {
+                final FlightInfo info = flightSqlClient.execute(query);
+                consume(info, 1, 11, false);
+            }
+            {
+                final PreparedStatement prepared = flightSqlClient.prepare(query);
+                {
+                    final FlightInfo info = prepared.execute();
+                    consume(info, 1, 11, false);
+                }
+                {
+                    final FlightInfo info = prepared.execute();
+                    consume(info, 1, 11, false);
+                }
+            }
+        } finally {
+            queryScope.putParam("my_table_2", null);
+            queryScope.putParam("my_table_1", null);
+        }
+
+    }
+
     private Result doAction(Action action) {
         final Iterator<Result> it = flightClient.doAction(action);
         if (!it.hasNext()) {