Merge bitcoin-core/gui#704: Correctly limit overview transaction list

08209c0 Correctly limit overview transaction list (John Moffett)

Pull request description:

  Fixes dashpay#703

  The way the main overview page limits the number of transactions displayed (currently 5) is not an appropriate use of Qt. Our subclassed transaction sort/filter proxy model returns a maximum of `5` in `rowCount()`. However, the model itself actually may hold significantly more. While this has _worked_, it breaks the contract of `rowCount()`.

  If `bitcoin-qt` is run with a DEBUG build of Qt, it'll result in an assert-crash in certain relatively common situations (see dashpay#703 for details). Instead of artificially limiting the `rowCount()` in the subclassed filter, we can hide/unhide the rows in the displaying `QListView` upon any changes in the sorted proxy filter.

  I loaded a wallet with 20,000 transactions and did not notice any performance differences between master and this branch.

  For reference, this is the list I'm referring to:

  <img width="934" alt="image" src="https://user-images.githubusercontent.com/116917595/214947304-3f289380-3510-487b-80e8-d19428cf2f0f.png">

ACKs for top commit:
  Sjors:
    tACK 08209c0
  hebasto:
    ACK 08209c0, tested on Ubuntu 22.04.

Tree-SHA512: c2a7b1a2a6e6ff30694830d7c722274c4c47494a81ce9ef25f8e5587c24871b02343969f4437507693d4fd40ba7a212702b159cf54b3357d8d76c02bc8245113

src/qt/overviewpage.cpp

@@ -262,7 +262,6 @@ void OverviewPage::setWalletModel(WalletModel *model)
         // Set up transaction list
         filter.reset(new TransactionFilterProxy());
         filter->setSourceModel(model->getTransactionTableModel());
-        filter->setLimit(NUM_ITEMS);
         filter->setDynamicSortFilter(true);
         filter->setSortRole(Qt::EditRole);
         filter->setShowInactive(false);
@@ -271,6 +270,10 @@ void OverviewPage::setWalletModel(WalletModel *model)
         ui->listTransactions->setModel(filter.get());
         ui->listTransactions->setModelColumn(TransactionTableModel::ToAddress);
 
+        connect(filter.get(), &TransactionFilterProxy::rowsInserted, this, &OverviewPage::LimitTransactionRows);
+        connect(filter.get(), &TransactionFilterProxy::rowsRemoved, this, &OverviewPage::LimitTransactionRows);
+        connect(filter.get(), &TransactionFilterProxy::rowsMoved, this, &OverviewPage::LimitTransactionRows);
+        LimitTransactionRows();
         // Keep up to date with wallet
         setBalance(model->getCachedBalance());
         connect(model, &WalletModel::balanceChanged, this, &OverviewPage::setBalance);
@@ -299,6 +302,16 @@ void OverviewPage::changeEvent(QEvent* e)
     QWidget::changeEvent(e);
 }
 
+// Only show most recent NUM_ITEMS rows
+void OverviewPage::LimitTransactionRows()
+{
+    if (filter && ui->listTransactions && ui->listTransactions->model() && filter.get() == ui->listTransactions->model()) {
+        for (int i = 0; i < filter->rowCount(); ++i) {
+            ui->listTransactions->setRowHidden(i, i >= NUM_ITEMS);
+        }
+    }
+}
+
 void OverviewPage::updateDisplayUnit()
 {
     if (walletModel && walletModel->getOptionsModel()) {

src/qt/overviewpage.h

@@ -60,6 +60,7 @@ public Q_SLOTS:
     std::unique_ptr<TransactionFilterProxy> filter;
 
 private Q_SLOTS:
+    void LimitTransactionRows();
     void updateDisplayUnit();
     void handleTransactionClicked(const QModelIndex &index);
     void updateAlerts(const QString &warnings);

src/qt/transactionfilterproxy.cpp

@@ -88,25 +88,8 @@ void TransactionFilterProxy::setWatchOnlyFilter(WatchOnlyFilter filter)
     invalidateFilter();
 }
 
-void TransactionFilterProxy::setLimit(int limit)
-{
-    this->limitRows = limit;
-}
-
 void TransactionFilterProxy::setShowInactive(bool _showInactive)
 {
     this->showInactive = _showInactive;
     invalidateFilter();
 }
-
-int TransactionFilterProxy::rowCount(const QModelIndex &parent) const
-{
-    if(limitRows != -1)
-    {
-        return std::min(QSortFilterProxyModel::rowCount(parent), limitRows);
-    }
-    else
-    {
-        return QSortFilterProxyModel::rowCount(parent);
-    }
-}

src/qt/transactionfilterproxy.h

@@ -42,14 +42,9 @@ class TransactionFilterProxy : public QSortFilterProxyModel
     void setMinAmount(const CAmount& minimum);
     void setWatchOnlyFilter(WatchOnlyFilter filter);
 
-    /** Set maximum number of rows returned, -1 if unlimited. */
-    void setLimit(int limit);
-
     /** Set whether to show conflicted transactions. */
     void setShowInactive(bool showInactive);
 
-    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
-
 protected:
     bool filterAcceptsRow(int source_row, const QModelIndex & source_parent) const override;
 
@@ -60,7 +55,6 @@ class TransactionFilterProxy : public QSortFilterProxyModel
     quint32 typeFilter;
     WatchOnlyFilter watchOnlyFilter{WatchOnlyFilter_All};
     CAmount minAmount{0};
-    int limitRows{-1};
     bool showInactive{true};
 };