fix: JS subscriptions should return correct size while updating (#6463)

Fixes #6423

web/client-api/src/main/java/io/deephaven/web/client/api/JsTable.java

@@ -452,7 +452,7 @@ public JsLayoutHints getLayoutHints() {
     @JsProperty
     public double getSize() {
         TableViewportSubscription subscription = subscriptions.get(getHandle());
-        if (subscription != null && subscription.getStatus() == TableViewportSubscription.Status.ACTIVE) {
+        if (subscription != null && subscription.hasValidSize()) {
             // only ask the viewport for the size if it is alive and ticking
             return subscription.size();
         }
@@ -705,7 +705,7 @@ public TableViewportSubscription setViewport(double firstRow, double lastRow,
         Column[] columnsCopy = columns != null ? Js.uncheckedCast(columns.slice()) : state().getColumns();
         ClientTableState currentState = state();
         TableViewportSubscription activeSubscription = subscriptions.get(getHandle());
-        if (activeSubscription != null && activeSubscription.getStatus() != TableViewportSubscription.Status.DONE) {
+        if (activeSubscription != null && !activeSubscription.isClosed()) {
             // hasn't finished, lets reuse it
             activeSubscription.setInternalViewport(firstRow, lastRow, columnsCopy, updateIntervalMs, isReverseViewport);
             return activeSubscription;
@@ -1583,8 +1583,7 @@ public void setState(final ClientTableState state) {
                 if (!isClosed() && was != null && was != state()) {
                     // if we held a subscription
                     TableViewportSubscription existingSubscription = subscriptions.remove(was.getHandle());
-                    if (existingSubscription != null
-                            && existingSubscription.getStatus() != TableViewportSubscription.Status.DONE) {
+                    if (existingSubscription != null && !existingSubscription.isClosed()) {
                         JsLog.debug("closing old viewport", state(), existingSubscription.state());
                         // with the replacement state successfully running, we can shut down the old viewport (unless
                         // something external retained it)
@@ -1715,7 +1714,7 @@ public void setSize(double s) {
         this.size = s;
 
         TableViewportSubscription subscription = subscriptions.get(getHandle());
-        if (changed && (subscription == null || subscription.getStatus() == TableViewportSubscription.Status.DONE)) {
+        if (changed && (subscription == null || !subscription.hasValidSize())) {
             // If the size changed, and we have no subscription active, fire. Otherwise, we want to let the
             // subscription itself manage this, so that the size changes are synchronized with data changes,
             // and consumers won't be confused by the table size not matching data.

web/client-api/src/main/java/io/deephaven/web/client/api/subscription/AbstractTableSubscription.java

@@ -61,7 +61,7 @@ public abstract class AbstractTableSubscription extends HasEventHandling {
      */
     public static final String EVENT_UPDATED = "updated";
 
-    public enum Status {
+    protected enum Status {
         /** Waiting for some prerequisite before we can use it for the first time. */
         STARTING,
         /** Successfully created, not waiting for any messages to be accurate. */
@@ -139,10 +139,6 @@ protected void revive() {
                 JsRunnable.doNothing());
     }
 
-    public Status getStatus() {
-        return status;
-    }
-
     protected static FlatBufferBuilder subscriptionRequest(byte[] tableTicket, BitSet columns,
             @Nullable RangeSet viewport,
             BarrageSubscriptionOptions options, boolean isReverseViewport) {
@@ -170,7 +166,7 @@ protected static FlatBufferBuilder subscriptionRequest(byte[] tableTicket, BitSe
 
     protected void sendBarrageSubscriptionRequest(RangeSet viewport, JsArray<Column> columns, Double updateIntervalMs,
             boolean isReverseViewport) {
-        if (status == Status.DONE) {
+        if (isClosed()) {
             if (failMsg == null) {
                 throw new IllegalStateException("Can't change subscription, already closed");
             } else {
@@ -214,15 +210,39 @@ protected WorkerConnection connection() {
         return connection;
     }
 
+    /**
+     * True if the subscription is in the ACTIVE state, meaning that the server and client are in sync with the state of
+     * the subscription.
+     */
     protected boolean isSubscriptionReady() {
         return status == Status.ACTIVE;
     }
 
+    /**
+     * Returns true if the subscription is closed and cannot be used again, false if it is actively listening for more
+     * data.
+     */
+    public boolean isClosed() {
+        return status == Status.DONE;
+    }
+
+    /**
+     * Returns true if the subscription is in a state where it can be used to read data, false if still waiting for the
+     * server to send the first snapshot or if the subscription has been closed.
+     * 
+     * @return true if the {@link #size()} method will return data based on the subscription, false if some other source
+     *         of the table's size will be used.
+     */
+    public boolean hasValidSize() {
+        return status == Status.ACTIVE || status == Status.PENDING_UPDATE;
+    }
+
+
     public double size() {
-        if (status == Status.ACTIVE) {
+        if (hasValidSize()) {
             return barrageSubscription.getCurrentSize();
         }
-        if (status == Status.DONE) {
+        if (isClosed()) {
             throw new IllegalStateException("Can't read size when already closed");
         }
         return state.getSize();
@@ -505,7 +525,7 @@ private void onFlightData(FlightData data) {
     }
 
     protected void onStreamEnd(ResponseStreamWrapper.Status status) {
-        if (this.status == Status.DONE) {
+        if (isClosed()) {
             return;
         }
         if (status.isTransportError()) {

web/client-api/src/main/java/io/deephaven/web/client/api/subscription/TableViewportSubscription.java

@@ -281,7 +281,7 @@ public void setInternalViewport(double firstRow, double lastRow, Column[] column
      */
     @JsMethod
     public void close() {
-        if (status == Status.DONE) {
+        if (isClosed()) {
             JsLog.warn("TableViewportSubscription.close called on subscription that's already done.");
         }
         retained = false;
@@ -300,14 +300,12 @@ public void internalClose() {
 
         reconnectSubscription.remove();
 
-        if (retained || status == Status.DONE) {
+        if (retained || isClosed()) {
             // the JsTable has indicated it is no longer interested in this viewport, but other calling
             // code has retained it, keep it open for now.
             return;
         }
 
-        status = Status.DONE;
-
         super.close();
     }