feat: Simplify Barrage Viewport Table Updates

engine/table/src/main/java/io/deephaven/engine/table/impl/util/BarrageMessage.java

@@ -48,11 +48,14 @@ public static class AddColumnData {
     /** The size of the table after this update. -1 if unknown. */
     public long tableSize = -1;
 
-    public boolean isSnapshot;
+    /** The RowSet the server is now respecting for this client; only set when parsing on the client. */
     public RowSet snapshotRowSet;
+    /** Whether the server-respecting viewport is a tail; only set when parsing on the client. */
     public boolean snapshotRowSetIsReversed;
+    /** The BitSet of columns the server is now respecting for this client; only set when parsing on the client. */
     public BitSet snapshotColumns;
 
+    public boolean isSnapshot;
     public RowSet rowsAdded;
     public RowSet rowsIncluded;
     public RowSet rowsRemoved;

extensions/barrage/src/main/java/io/deephaven/extensions/barrage/BarrageStreamGeneratorImpl.java

@@ -242,7 +242,7 @@ private final class SubView implements RecordBatchMessageView {
         private final boolean isFullSubscription;
         private final RowSet viewport;
         private final boolean reverseViewport;
-        private final RowSet keyspaceViewport;
+        private final boolean hasViewport;
         private final BitSet subscribedColumns;
 
         private final long numClientIncludedRows;
@@ -266,7 +266,7 @@ public SubView(final BarrageSubscriptionOptions options,
             this.isFullSubscription = isFullSubscription;
             this.viewport = viewport;
             this.reverseViewport = reverseViewport;
-            this.keyspaceViewport = keyspaceViewport;
+            this.hasViewport = keyspaceViewport != null;
             this.subscribedColumns = subscribedColumns;
 
             // precompute the included rows / offsets and viewport removed rows
@@ -491,7 +491,7 @@ private ByteBuffer getSubscriptionMetadata() throws IOException {
             TIntArrayList modOffsets = new TIntArrayList(modColumnData.length);
             for (int ii = 0; ii < modColumnData.length; ++ii) {
                 final int myModRowOffset;
-                if (keyspaceViewport != null) {
+                if (hasViewport) {
                     try (final RowSetGenerator modRowsGen = new RowSetGenerator(clientModdedRows[ii])) {
                         myModRowOffset = modRowsGen.addToFlatBuffer(metadata);
                     }
@@ -1152,7 +1152,7 @@ protected void ensureComputed() throws IOException {
                 }
 
                 try (final ExposedByteArrayOutputStream baos = new ExposedByteArrayOutputStream();
-                     final LittleEndianDataOutputStream oos = new LittleEndianDataOutputStream(baos)) {
+                        final LittleEndianDataOutputStream oos = new LittleEndianDataOutputStream(baos)) {
                     ExternalizableRowSetUtils.writeExternalCompressedDeltas(oos, original);
                     oos.flush();
                     len = baos.size();
@@ -1181,8 +1181,8 @@ protected int addToFlatBuffer(final RowSet viewport, final FlatBufferBuilder bui
                     final RowSet viewOfOriginal = original.intersect(viewport)) {
                 ExternalizableRowSetUtils.writeExternalCompressedDeltas(oos, viewOfOriginal);
                 oos.flush();
-                nraw = baos.peekBuffer();
                 nlen = baos.size();
+                nraw = baos.peekBuffer();
             }
 
             return builder.createByteVector(nraw, 0, nlen);

server/src/main/java/io/deephaven/server/barrage/BarrageMessageProducer.java

@@ -1379,6 +1379,7 @@ private void updateSubscriptionsSnapshotAndPropagate() {
                     if (!snapshot.rowsAdded.isEmpty()) {
                         snapshot.rowsAdded.close();
                         snapshot.rowsAdded = RowSetFactory.empty();
+                        snapshot.tableSize = 0;
                     }
                 }
                 long elapsed = System.nanoTime() - start;

server/src/main/java/io/deephaven/server/hierarchicaltable/HierarchicalTableViewSubscription.java

@@ -323,17 +323,14 @@ private static void buildAndSendSnapshot(
                 columns, rows, destinations);
         snapshotNanosConsumer.accept(System.nanoTime() - snapshotStartNanos);
 
-        // note that keyspace is identical to position space for HierarchicalTableView snapshots
-        final RowSet snapshotRows = RowSetFactory.flat(expandedSize);
-        final RowSet keyspaceViewportRows = rows.intersect(snapshotRows);
-
         // 4. Make and populate a BarrageMessage
         final BarrageMessage barrageMessage = new BarrageMessage();
-        // We don't populate firstSeq, or lastSeq debugging information; they are not relevant to this use case.
+        // We don't populate firstSeq or lastSeq debugging information; they are not relevant to this use case.
 
         barrageMessage.isSnapshot = true;
-        barrageMessage.rowsAdded = snapshotRows;
-        barrageMessage.rowsIncluded = keyspaceViewportRows;
+        barrageMessage.rowsAdded = RowSetFactory.flat(expandedSize);
+        barrageMessage.rowsIncluded = RowSetFactory.fromRange(
+                rows.firstRowKey(), Math.min(expandedSize - 1, rows.lastRowKey()));
         barrageMessage.rowsRemoved = RowSetFactory.empty();
         barrageMessage.shifted = RowSetShiftData.EMPTY;
         barrageMessage.tableSize = expandedSize;
@@ -365,11 +362,10 @@ private static void buildAndSendSnapshot(
             final boolean isFullSubscription = false;
             GrpcUtil.safelyOnNext(listener, streamGenerator.getSubView(
                     subscriptionOptions, initialSnapshot, isFullSubscription, rows, false,
-                    prevKeyspaceViewportRows, keyspaceViewportRows, columns));
-        }
+                    prevKeyspaceViewportRows, barrageMessage.rowsIncluded, columns));
 
-        prevKeyspaceViewportRows.clear();
-        prevKeyspaceViewportRows.insert(keyspaceViewportRows);
+            prevKeyspaceViewportRows.resetTo(barrageMessage.rowsIncluded);
+        }
     }
 
     public void setViewport(