optimize fetching mempool entries for fee histogram when connected to bitcoin core, fix and improve mempool fee rates chart

src/main/java/com/sparrowwallet/sparrow/AppServices.java

@@ -669,6 +669,10 @@ public class AppServices {
     }
 
     private void addMempoolRateSizes(Set<MempoolRateSize> rateSizes) {
+        if(rateSizes.isEmpty()) {
+            return;
+        }
+
         LocalDateTime dateMinute = LocalDateTime.now().truncatedTo(ChronoUnit.MINUTES);
         if(mempoolHistogram.isEmpty()) {
             mempoolHistogram.put(Date.from(dateMinute.minusMinutes(1).atZone(ZoneId.systemDefault()).toInstant()), rateSizes);
@@ -1022,8 +1026,6 @@ public class AppServices {
     public void newConnection(ConnectionEvent event) {
         currentBlockHeight = event.getBlockHeight();
         System.setProperty(Network.BLOCK_HEIGHT_PROPERTY, Integer.toString(currentBlockHeight));
-        targetBlockFeeRates = event.getTargetBlockFeeRates();
-        addMempoolRateSizes(event.getMempoolRateSizes());
         minimumRelayFeeRate = Math.max(event.getMinimumRelayFeeRate(), Transaction.DEFAULT_MIN_RELAY_FEE);
         latestBlockHeader = event.getBlockHeader();
         Config.get().addRecentServer();
@@ -1046,6 +1048,10 @@ public class AppServices {
     @Subscribe
     public void feesUpdated(FeeRatesUpdatedEvent event) {
         targetBlockFeeRates = event.getTargetBlockFeeRates();
+    }
+
+    @Subscribe
+    public void mempoolRateSizes(MempoolRateSizesUpdatedEvent event) {
         addMempoolRateSizes(event.getMempoolRateSizes());
     }
 

src/main/java/com/sparrowwallet/sparrow/control/MempoolSizeFeeRatesChart.java

@@ -1,19 +1,31 @@
 package com.sparrowwallet.sparrow.control;
 
 import com.sparrowwallet.sparrow.AppServices;
+import com.sparrowwallet.sparrow.Theme;
 import com.sparrowwallet.sparrow.glyphfont.FontAwesome5;
+import com.sparrowwallet.sparrow.io.Config;
 import com.sparrowwallet.sparrow.net.MempoolRateSize;
 import javafx.application.Platform;
 import javafx.beans.NamedArg;
 import javafx.collections.FXCollections;
+import javafx.event.EventHandler;
+import javafx.geometry.Insets;
 import javafx.geometry.Point2D;
+import javafx.geometry.Pos;
 import javafx.scene.Cursor;
 import javafx.scene.Node;
+import javafx.scene.Scene;
 import javafx.scene.chart.*;
+import javafx.scene.control.Button;
 import javafx.scene.control.Label;
 import javafx.scene.control.Tooltip;
-import javafx.scene.layout.HBox;
+import javafx.scene.input.MouseButton;
-import javafx.scene.layout.VBox;
+import javafx.scene.input.MouseEvent;
+import javafx.scene.layout.*;
+import javafx.scene.paint.Color;
+import javafx.stage.Modality;
+import javafx.stage.Stage;
+import javafx.stage.StageStyle;
 import javafx.util.Duration;
 import javafx.util.StringConverter;
 import org.controlsfx.glyphfont.Glyph;
@@ -29,14 +41,80 @@ public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
     private static final DateFormat dateFormatter = new SimpleDateFormat("HH:mm");
     public static final int MAX_PERIOD_HOURS = 2;
     private static final double Y_VALUE_BREAK_MVB = 3.0;
+    private static final List<Integer> FEE_RATES_INTERVALS = List.of(1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 250, 300, 350, 400, 500, 600, 700, 800);
 
     private Tooltip tooltip;
 
+    private MempoolSizeFeeRatesChart expandedChart;
+    private final EventHandler<MouseEvent> expandedChartHandler = new EventHandler<>() {
+        @Override
+        public void handle(MouseEvent event) {
+            if(!event.isConsumed() && event.getButton() != MouseButton.SECONDARY) {
+                Stage stage = new Stage(StageStyle.UNDECORATED);
+                stage.setTitle("Mempool by vBytes");
+                stage.initOwner(MempoolSizeFeeRatesChart.this.getScene().getWindow());
+                stage.initModality(Modality.WINDOW_MODAL);
+                stage.setResizable(false);
+
+                StackPane scenePane = new StackPane();
+                if(org.controlsfx.tools.Platform.getCurrent() == org.controlsfx.tools.Platform.WINDOWS) {
+                    scenePane.setBorder(new Border(new BorderStroke(Color.DARKGRAY, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, BorderWidths.DEFAULT)));
+                }
+
+                scenePane.getStylesheets().add(AppServices.class.getResource("general.css").toExternalForm());
+                if(Config.get().getTheme() == Theme.DARK) {
+                    scenePane.getStylesheets().add(AppServices.class.getResource("darktheme.css").toExternalForm());
+                }
+                scenePane.getStylesheets().add(AppServices.class.getResource("wallet/wallet.css").toExternalForm());
+                scenePane.getStylesheets().add(AppServices.class.getResource("wallet/send.css").toExternalForm());
+
+                VBox vBox = new VBox(20);
+                vBox.setPadding(new Insets(20, 20, 20, 20));
+
+                expandedChart = new MempoolSizeFeeRatesChart();
+                expandedChart.initialize();
+                expandedChart.getStyleClass().add("vsizeChart");
+                expandedChart.update(AppServices.getMempoolHistogram());
+                expandedChart.setLegendVisible(false);
+                expandedChart.setAnimated(false);
+                expandedChart.setPrefWidth(700);
+
+                HBox buttonBox = new HBox();
+                buttonBox.setAlignment(Pos.CENTER_RIGHT);
+                Button button = new Button("Close");
+                button.setOnAction(e -> {
+                    stage.close();
+                });
+                buttonBox.getChildren().add(button);
+                vBox.getChildren().addAll(expandedChart, buttonBox);
+                scenePane.getChildren().add(vBox);
+
+                Scene scene = new Scene(scenePane);
+                AppServices.onEscapePressed(scene, stage::close);
+                AppServices.setStageIcon(stage);
+                stage.setScene(scene);
+                stage.setOnShowing(e -> {
+                    AppServices.moveToActiveWindowScreen(stage, 800, 460);
+                });
+                stage.setOnHidden(e -> {
+                    expandedChart = null;
+                });
+                stage.show();
+            }
+        }
+    };
+
+    public MempoolSizeFeeRatesChart() {
+        super(new CategoryAxis(), new NumberAxis());
+    }
+
     public MempoolSizeFeeRatesChart(@NamedArg("xAxis") Axis<String> xAxis, @NamedArg("yAxis") Axis<Number> yAxis) {
         super(xAxis, yAxis);
+        setOnMouseClicked(expandedChartHandler);
     }
 
     public void initialize() {
+        getStyleClass().add("vsizeChart");
         setCreateSymbols(false);
         setCursor(Cursor.CROSSHAIR);
         setVerticalGridLinesVisible(false);
@@ -78,17 +156,18 @@ public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
             }
         });
 
-        long previousFeeRate = 0;
+        for(int i = 0; i < FEE_RATES_INTERVALS.size(); i++) {
-        for(Long feeRate : AppServices.FEE_RATES_RANGE) {
+            int feeRate = FEE_RATES_INTERVALS.get(i);
+            int nextFeeRate = (i == FEE_RATES_INTERVALS.size() - 1 ? Integer.MAX_VALUE : FEE_RATES_INTERVALS.get(i+1));
             XYChart.Series<String, Number> series = new XYChart.Series<>();
-            series.setName(feeRate + "+ sats/vB");
+            series.setName(feeRate + "-" + (nextFeeRate == Integer.MAX_VALUE ? 900 : nextFeeRate));
             long seriesTotalVSize = 0;
 
             for(Date date : periodRateSizes.keySet()) {
                 Set<MempoolRateSize> rateSizes = periodRateSizes.get(date);
                 long totalVSize = 0;
                 for(MempoolRateSize rateSize : rateSizes) {
-                    if(rateSize.getFee() > previousFeeRate && rateSize.getFee() <= feeRate) {
+                    if(rateSize.getFee() >= feeRate && rateSize.getFee() < nextFeeRate) {
                         totalVSize += rateSize.getVSize();
                     }
                 }
@@ -100,8 +179,19 @@ public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
             if(seriesTotalVSize > 0) {
                 getData().add(series);
             }
+        }
 
-            previousFeeRate = feeRate;
+        for(int i = 0; i < getData().size(); i++) {
+            Series<String, Number> series = getData().get(i);
+            Set<Node> nodes = lookupAll(".series" + i);
+            for(Node node : nodes) {
+                if(node.getStyleClass().contains("chart-series-area-line")) {
+                    node.setStyle("-fx-stroke: VSIZE" + series.getName() + "_COLOR; -fx-opacity: 0.2;");
+                } else {
+                    node.setStyle("-fx-fill: VSIZE" + series.getName() + "_COLOR; -fx-opacity: 0.5;");
+                }
+                node.getStyleClass().remove("default-color" + i);
+            }
         }
 
         final double maxMvB = getMaxMvB(getData());
@@ -131,6 +221,10 @@ public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
             numberAxis.setTickLabelsVisible(false);
             numberAxis.setOpacity(0);
         }
+
+        if(expandedChart != null) {
+            expandedChart.update(mempoolRateSizes);
+        }
     }
 
     private Map<Date, Set<MempoolRateSize>> getPeriodRateSizes(Map<Date, Set<MempoolRateSize>> mempoolRateSizes) {
@@ -200,11 +294,9 @@ public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
                         double mvb = kvb / 1000;
                         if(mvb >= 0.01 || (maxMvB < Y_VALUE_BREAK_MVB && mvb > 0.001)) {
                             String amount = (maxMvB < Y_VALUE_BREAK_MVB ? (int)kvb + " kvB" : String.format("%.2f", mvb) + " MvB");
-                            Label label = new Label(series.getName() + ": " + amount);
+                            Label label = new Label(series.getName() + " sats/vB: " + amount);
                             Glyph circle = new Glyph(FontAwesome5.FONT_NAME, FontAwesome5.Glyph.CIRCLE);
-                            if(i < 8) {
+                            circle.setStyle("-fx-text-fill: VSIZE" + series.getName() + "_COLOR; -fx-opacity: 0.7;");
-                                circle.setStyle("-fx-text-fill: CHART_COLOR_" + (i+1));
-                            }
                             label.setGraphic(circle);
                             getChildren().add(label);
                         }

src/main/java/com/sparrowwallet/sparrow/event/FeeRatesUpdatedEvent.java

@@ -5,20 +5,15 @@ import com.sparrowwallet.sparrow.net.MempoolRateSize;
 import java.util.Map;
 import java.util.Set;
 
-public class FeeRatesUpdatedEvent {
+public class FeeRatesUpdatedEvent extends MempoolRateSizesUpdatedEvent {
     private final Map<Integer, Double> targetBlockFeeRates;
-    private final Set<MempoolRateSize> mempoolRateSizes;
 
     public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Set<MempoolRateSize> mempoolRateSizes) {
+        super(mempoolRateSizes);
         this.targetBlockFeeRates = targetBlockFeeRates;
-        this.mempoolRateSizes = mempoolRateSizes;
     }
 
     public Map<Integer, Double> getTargetBlockFeeRates() {
         return targetBlockFeeRates;
     }
-
-    public Set<MempoolRateSize> getMempoolRateSizes() {
-        return mempoolRateSizes;
-    }
 }

src/main/java/com/sparrowwallet/sparrow/event/MempoolEntriesInitializedEvent.java

@@ -0,0 +1,8 @@
+package com.sparrowwallet.sparrow.event;
+
+/**
+ * The event is posted when the first set of mempool entries (txid and vsizes) have been retrieved from the node.
+ * Cormorant only.
+ */
+public class MempoolEntriesInitializedEvent {
+}

src/main/java/com/sparrowwallet/sparrow/event/MempoolRateSizesUpdatedEvent.java

@@ -0,0 +1,17 @@
+package com.sparrowwallet.sparrow.event;
+
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
+
+import java.util.Set;
+
+public class MempoolRateSizesUpdatedEvent {
+    private final Set<MempoolRateSize> mempoolRateSizes;
+
+    public MempoolRateSizesUpdatedEvent(Set<MempoolRateSize> mempoolRateSizes) {
+        this.mempoolRateSizes = mempoolRateSizes;
+    }
+
+    public Set<MempoolRateSize> getMempoolRateSizes() {
+        return mempoolRateSizes;
+    }
+}

src/main/java/com/sparrowwallet/sparrow/net/BatchedElectrumServerRpc.java

@@ -12,7 +12,7 @@ import com.sparrowwallet.sparrow.event.WalletHistoryStatusEvent;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.math.BigInteger;
+import java.math.BigDecimal;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Collectors;
@@ -235,16 +235,16 @@ public class BatchedElectrumServerRpc implements ElectrumServerRpc {
     }
 
     @Override
-    public Map<Long, Long> getFeeRateHistogram(Transport transport) {
+    public Map<Double, Long> getFeeRateHistogram(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            BigInteger[][] feesArray = new RetryLogic<BigInteger[][]>(DEFAULT_MAX_ATTEMPTS, RETRY_DELAY_SECS, IllegalStateException.class).getResult(() ->
+            BigDecimal[][] feesArray = new RetryLogic<BigDecimal[][]>(DEFAULT_MAX_ATTEMPTS, RETRY_DELAY_SECS, IllegalStateException.class).getResult(() ->
-                    client.createRequest().returnAs(BigInteger[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
+                    client.createRequest().returnAs(BigDecimal[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
 
-            Map<Long, Long> feeRateHistogram = new TreeMap<>();
+            Map<Double, Long> feeRateHistogram = new TreeMap<>();
-            for(BigInteger[] feePair : feesArray) {
+            for(BigDecimal[] feePair : feesArray) {
                 if(feePair[0].longValue() > 0) {
-                    feeRateHistogram.put(feePair[0].longValue(), feePair[1].longValue());
+                    feeRateHistogram.put(feePair[0].doubleValue(), feePair[1].longValue());
                 }
             }
 

src/main/java/com/sparrowwallet/sparrow/net/ElectrumServer.java

@@ -836,9 +836,9 @@ public class ElectrumServer {
     }
 
     public Set<MempoolRateSize> getMempoolRateSizes() throws ServerException {
-        Map<Long, Long> feeRateHistogram = electrumServerRpc.getFeeRateHistogram(getTransport());
+        Map<Double, Long> feeRateHistogram = electrumServerRpc.getFeeRateHistogram(getTransport());
         Set<MempoolRateSize> mempoolRateSizes = new TreeSet<>();
-        for(Long fee : feeRateHistogram.keySet()) {
+        for(Double fee : feeRateHistogram.keySet()) {
             mempoolRateSizes.add(new MempoolRateSize(fee, feeRateHistogram.get(fee)));
         }
 
@@ -1331,6 +1331,13 @@ public class ElectrumServer {
                 bwtStartLock.unlock();
             }
         }
+
+        @Subscribe
+        public void mempoolEntriesInitialized(MempoolEntriesInitializedEvent event) throws ServerException {
+            ElectrumServer electrumServer = new ElectrumServer();
+            Set<MempoolRateSize> mempoolRateSizes = electrumServer.getMempoolRateSizes();
+            EventManager.get().post(new MempoolRateSizesUpdatedEvent(mempoolRateSizes));
+        }
     }
 
     public static class ReadRunnable implements Runnable {

src/main/java/com/sparrowwallet/sparrow/net/ElectrumServerRpc.java

@@ -30,7 +30,7 @@ public interface ElectrumServerRpc {
 
     Map<Integer, Double> getFeeEstimates(Transport transport, List<Integer> targetBlocks);
 
-    Map<Long, Long> getFeeRateHistogram(Transport transport);
+    Map<Double, Long> getFeeRateHistogram(Transport transport);
 
     Double getMinimumRelayFee(Transport transport);
 

src/main/java/com/sparrowwallet/sparrow/net/MempoolRateSize.java

@@ -3,15 +3,15 @@ package com.sparrowwallet.sparrow.net;
 import java.util.Objects;
 
 public class MempoolRateSize implements Comparable<MempoolRateSize> {
-    private final long fee;
+    private final double fee;
     private final long vSize;
 
-    public MempoolRateSize(long fee, long vSize) {
+    public MempoolRateSize(double fee, long vSize) {
         this.fee = fee;
         this.vSize = vSize;
     }
 
-    public long getFee() {
+    public double getFee() {
         return fee;
     }
 
@@ -38,7 +38,7 @@ public class MempoolRateSize implements Comparable<MempoolRateSize> {
 
     @Override
     public int compareTo(MempoolRateSize other) {
-        return Long.compare(fee, other.fee);
+        return Double.compare(fee, other.fee);
     }
 
     @Override

src/main/java/com/sparrowwallet/sparrow/net/SimpleElectrumServerRpc.java

@@ -13,7 +13,7 @@ import com.sparrowwallet.sparrow.event.WalletHistoryStatusEvent;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.math.BigInteger;
+import java.math.BigDecimal;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicLong;
 
@@ -260,16 +260,16 @@ public class SimpleElectrumServerRpc implements ElectrumServerRpc {
     }
 
     @Override
-    public Map<Long, Long> getFeeRateHistogram(Transport transport) {
+    public Map<Double, Long> getFeeRateHistogram(Transport transport) {
         try {
             JsonRpcClient client = new JsonRpcClient(transport);
-            BigInteger[][] feesArray = new RetryLogic<BigInteger[][]>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
+            BigDecimal[][] feesArray = new RetryLogic<BigDecimal[][]>(MAX_RETRIES, RETRY_DELAY, IllegalStateException.class).getResult(() ->
-                    client.createRequest().returnAs(BigInteger[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
+                    client.createRequest().returnAs(BigDecimal[][].class).method("mempool.get_fee_histogram").id(idCounter.incrementAndGet()).execute());
 
-            Map<Long, Long> feeRateHistogram = new TreeMap<>();
+            Map<Double, Long> feeRateHistogram = new TreeMap<>();
-            for(BigInteger[] feePair : feesArray) {
+            for(BigDecimal[] feePair : feesArray) {
                 if(feePair[0].longValue() > 0) {
-                    feeRateHistogram.put(feePair[0].longValue(), feePair[1].longValue());
+                    feeRateHistogram.put(feePair[0].doubleValue(), feePair[1].longValue());
                 }
             }
 

src/main/java/com/sparrowwallet/sparrow/net/cormorant/Cormorant.java

@@ -35,7 +35,7 @@ public class Cormorant {
     }
 
     public Server start() throws CormorantBitcoindException {
-        bitcoindClient = new BitcoindClient();
+        bitcoindClient = new BitcoindClient(useWallets);
         bitcoindClient.initialize();
 
         Thread importThread = new Thread(() -> {

src/main/java/com/sparrowwallet/sparrow/net/cormorant/bitcoind/BitcoindClient.java

@@ -2,6 +2,7 @@ package com.sparrowwallet.sparrow.net.cormorant.bitcoind;
 
 import com.github.arteam.simplejsonrpc.client.JsonRpcClient;
 import com.github.arteam.simplejsonrpc.client.exception.JsonRpcException;
+import com.google.common.collect.Sets;
 import com.sparrowwallet.drongo.KeyPurpose;
 import com.sparrowwallet.drongo.OutputDescriptor;
 import com.sparrowwallet.drongo.Utils;
@@ -25,11 +26,14 @@ import com.sparrowwallet.sparrow.net.cormorant.electrum.ScriptHashStatus;
 import com.sparrowwallet.sparrow.net.cormorant.index.Store;
 import com.sparrowwallet.drongo.protocol.*;
 import javafx.application.Platform;
+import javafx.concurrent.Service;
+import javafx.concurrent.Task;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.time.Duration;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
@@ -60,6 +64,7 @@ public class BitcoindClient {
 
     private Exception lastPollException;
 
+    private final boolean useWallets;
     private boolean pruned;
     private boolean legacyWalletExists;
 
@@ -76,7 +81,11 @@ public class BitcoindClient {
 
     private final List<String> pruneWarnedDescriptors = new ArrayList<>();
 
-    public BitcoindClient() {
+    private final Map<String, MempoolEntry> mempoolEntries = new ConcurrentHashMap<>();
+    private MempoolEntriesState mempoolEntriesState = MempoolEntriesState.UNINITIALIZED;
+    private long timerTaskCount;
+
+    public BitcoindClient(boolean useWallets) {
         BitcoindTransport bitcoindTransport;
 
         Config config = Config.get();
@@ -87,6 +96,7 @@ public class BitcoindClient {
         }
 
         this.jsonRpcClient = new JsonRpcClient(bitcoindTransport);
+        this.useWallets = useWallets;
     }
 
     public void initialize() throws CormorantBitcoindException {
@@ -516,6 +526,64 @@ public class BitcoindClient {
         }
     }
 
+    public void initializeMempoolEntries() {
+        mempoolEntriesState = MempoolEntriesState.INITIALIZING;
+
+        long start = System.currentTimeMillis();
+        Set<String> txids = getBitcoindService().getRawMempool();
+        long end = System.currentTimeMillis();
+
+        if(end - start < 1000) {
+            //Fast system, fetch all mempool data at once
+            mempoolEntries.putAll(getBitcoindService().getRawMempool(true));
+        } else {
+            //Slow system, fetch mempool entries one-by-one to avoid risking a node crash
+            for(String txid : txids) {
+                try {
+                    MempoolEntry mempoolEntry = getBitcoindService().getMempoolEntry(txid);
+                    mempoolEntries.put(txid, mempoolEntry);
+                } catch(JsonRpcException e) {
+                    //ignore, probably tx has been removed from mempool
+                }
+            }
+        }
+
+        mempoolEntriesState = MempoolEntriesState.INITIALIZED;
+    }
+
+    public void updateMempoolEntries() {
+        Set<String> txids = getBitcoindService().getRawMempool();
+
+        Set<String> removed = new HashSet<>(Sets.difference(mempoolEntries.keySet(), txids));
+        mempoolEntries.keySet().removeAll(removed);
+
+        Set<String> added = Sets.difference(txids, mempoolEntries.keySet());
+        for(String txid : added) {
+            try {
+                MempoolEntry mempoolEntry = getBitcoindService().getMempoolEntry(txid);
+                mempoolEntries.put(txid, mempoolEntry);
+            } catch(JsonRpcException e) {
+                //ignore, probably tx has been removed from mempool
+            }
+        }
+    }
+
+    public Map<String, MempoolEntry> getMempoolEntries() {
+        return mempoolEntries;
+    }
+
+    public MempoolEntriesState getMempoolEntriesState() {
+        return mempoolEntriesState;
+    }
+
+    public InitializeMempoolEntriesService getInitializeMempoolEntriesService() {
+        return new InitializeMempoolEntriesService();
+    }
+
+    public boolean isUseWallets() {
+        return useWallets;
+    }
+
     public Store getStore() {
         return store;
     }
@@ -566,6 +634,10 @@ public class BitcoindClient {
                     }
                 }
 
+                if(mempoolEntriesState == MempoolEntriesState.INITIALIZED && (++timerTaskCount+1) % 12 == 0) {
+                    updateMempoolEntries();
+                }
+
                 ListSinceBlock listSinceBlock = getListSinceBlock(lastBlock);
                 String currentBlock = lastBlock;
                 updateStore(listSinceBlock);
@@ -591,7 +663,7 @@ public class BitcoindClient {
                 }
             } catch(Exception e) {
                 lastPollException = e;
-                log.warn("Error polling Bitcoin Core: " + e.getMessage());
+                log.warn("Error polling Bitcoin Core", e);
 
                 if(syncing) {
                     syncingLock.lock();
@@ -627,4 +699,21 @@ public class BitcoindClient {
             return rescanSince == null ? "now" : rescanSince.getTime() / 1000;
         }
     }
+
+    public class InitializeMempoolEntriesService extends Service<Void> {
+        @Override
+        protected Task<Void> createTask() {
+            return new Task<>() {
+                @Override
+                protected Void call() {
+                    initializeMempoolEntries();
+                    return null;
+                }
+            };
+        }
+    }
+
+    public enum MempoolEntriesState {
+        UNINITIALIZED, INITIALIZING, INITIALIZED
+    }
 }

src/main/java/com/sparrowwallet/sparrow/net/cormorant/bitcoind/BitcoindClientService.java

@@ -9,6 +9,7 @@ import com.github.arteam.simplejsonrpc.core.annotation.JsonRpcService;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 @JsonRpcService
 @JsonRpcParams(ParamsType.ARRAY)
@@ -22,6 +23,9 @@ public interface BitcoindClientService {
     @JsonRpcMethod("estimatesmartfee")
     FeeInfo estimateSmartFee(@JsonRpcParam("conf_target") int blocks);
 
+    @JsonRpcMethod("getrawmempool")
+    Set<String> getRawMempool();
+
     @JsonRpcMethod("getrawmempool")
     Map<String, MempoolEntry> getRawMempool(@JsonRpcParam("verbose") boolean verbose);
 

src/main/java/com/sparrowwallet/sparrow/net/cormorant/electrum/ElectrumServerService.java

@@ -5,7 +5,10 @@ import com.github.arteam.simplejsonrpc.core.annotation.JsonRpcMethod;
 import com.github.arteam.simplejsonrpc.core.annotation.JsonRpcOptional;
 import com.github.arteam.simplejsonrpc.core.annotation.JsonRpcParam;
 import com.github.arteam.simplejsonrpc.core.annotation.JsonRpcService;
+import com.sparrowwallet.drongo.protocol.Transaction;
+import com.sparrowwallet.sparrow.EventManager;
 import com.sparrowwallet.sparrow.SparrowWallet;
+import com.sparrowwallet.sparrow.event.MempoolEntriesInitializedEvent;
 import com.sparrowwallet.sparrow.net.Version;
 import com.sparrowwallet.sparrow.net.cormorant.Cormorant;
 import com.sparrowwallet.sparrow.net.cormorant.bitcoind.*;
@@ -60,9 +63,23 @@ public class ElectrumServerService {
     }
 
     @JsonRpcMethod("mempool.get_fee_histogram")
-    public List<List<Number>> getFeeHistogram() throws BitcoindIOException {
+    public List<List<Number>> getFeeHistogram() {
-        try {
+        BitcoindClient.MempoolEntriesState mempoolEntriesState = bitcoindClient.getMempoolEntriesState();
-            Map<String, MempoolEntry> mempoolEntries = bitcoindClient.getBitcoindService().getRawMempool(true);
+        if(mempoolEntriesState != BitcoindClient.MempoolEntriesState.INITIALIZED) {
+            if(bitcoindClient.isUseWallets() && mempoolEntriesState == BitcoindClient.MempoolEntriesState.UNINITIALIZED) {
+                BitcoindClient.InitializeMempoolEntriesService initializeMempoolEntriesService = bitcoindClient.getInitializeMempoolEntriesService();
+                initializeMempoolEntriesService.setOnSucceeded(successEvent -> {
+                    EventManager.get().post(new MempoolEntriesInitializedEvent());
+                });
+                initializeMempoolEntriesService.setOnFailed(failedEvent -> {
+                    log.error("Failed to initialize mempool entries", failedEvent.getSource().getException());
+                });
+                initializeMempoolEntriesService.start();
+            }
+
+            return Collections.emptyList();
+        } else {
+            Map<String, MempoolEntry> mempoolEntries = bitcoindClient.getMempoolEntries();
 
             List<VsizeFeerate> vsizeFeerates = mempoolEntries.values().stream().map(entry -> new VsizeFeerate(entry.vsize(), entry.fees().base())).sorted().toList();
 
@@ -85,8 +102,6 @@ public class ElectrumServerService {
             }
 
             return histogram;
-        } catch(IllegalStateException e) {
-            throw new BitcoindIOException(e);
         }
     }
 
@@ -204,7 +219,9 @@ public class ElectrumServerService {
 
         public VsizeFeerate(int vsize, double fee) {
             this.vsize = vsize;
-            this.feerate = fee / vsize * 100000000;
+            double feeRate = fee / vsize * Transaction.SATOSHIS_PER_BITCOIN;
+            //Round down to 0.1 sats/vb precision
+            this.feerate = Math.floor(10 * feeRate) / 10;
         }
 
         @Override

src/main/java/com/sparrowwallet/sparrow/wallet/SendController.java

@@ -1508,7 +1508,6 @@ public class SendController extends WalletFormController implements Initializabl
     public void feeRatesUpdated(FeeRatesUpdatedEvent event) {
         blockTargetFeeRatesChart.update(event.getTargetBlockFeeRates());
         blockTargetFeeRatesChart.select(getTargetBlocks());
-        mempoolSizeFeeRatesChart.update(getMempoolHistogram());
         if(targetBlocksField.isVisible()) {
             setFeeRate(event.getTargetBlockFeeRates().get(getTargetBlocks()));
         } else {
@@ -1517,6 +1516,11 @@ public class SendController extends WalletFormController implements Initializabl
         addFeeRangeTrackHighlight(0);
     }
 
+    @Subscribe
+    public void mempoolRateSizesUpdated(MempoolRateSizesUpdatedEvent event) {
+        mempoolSizeFeeRatesChart.update(getMempoolHistogram());
+    }
+
     @Subscribe
     public void feeRateSelectionChanged(FeeRatesSelectionChangedEvent event) {
         if(event.getWallet() == getWalletForm().getWallet()) {

src/main/java/com/sparrowwallet/sparrow/whirlpool/dataPersister/SparrowUtxoConfigPersister.java

@@ -16,6 +16,7 @@ import org.slf4j.LoggerFactory;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
 public class SparrowUtxoConfigPersister extends UtxoConfigPersister {
@@ -38,7 +39,7 @@ public class SparrowUtxoConfigPersister extends UtxoConfigPersister {
         Map<String, UtxoConfigPersisted> utxoConfigs = wallet.getUtxoMixes().entrySet().stream()
                 .collect(Collectors.toMap(entry -> entry.getKey().toString(), entry -> new UtxoConfigPersisted(entry.getValue().getMixesDone(), entry.getValue().getExpired()),
                         (u, v) -> { throw new IllegalStateException("Duplicate utxo config hashes"); },
-                        HashMap::new));
+                        ConcurrentHashMap::new));
 
         return new UtxoConfigData(utxoConfigs);
     }

src/main/resources/com/sparrowwallet/sparrow/wallet/send.css

@@ -131,3 +131,36 @@
 #transactionDiagram .useradd-icon {
     -fx-text-fill: -fx-accent;
 }
+
+.vsizeChart {
+    VSIZE1-2_COLOR: rgb(216, 27, 96);
+    VSIZE2-3_COLOR: rgb(142, 36, 170);
+    VSIZE3-4_COLOR: rgb(94, 53, 177);
+    VSIZE4-5_COLOR: rgb(57, 73, 171);
+    VSIZE5-6_COLOR: rgb(30, 136, 229);
+    VSIZE6-8_COLOR: rgb(3, 155, 229);
+    VSIZE8-10_COLOR: rgb(0, 172, 193);
+    VSIZE10-12_COLOR: rgb(0, 137, 123);
+    VSIZE12-15_COLOR: rgb(67, 160, 71);
+    VSIZE15-20_COLOR: rgb(124, 179, 66);
+    VSIZE20-30_COLOR: rgb(192, 202, 51);
+    VSIZE30-40_COLOR: rgb(253, 216, 53);
+    VSIZE40-50_COLOR: rgb(255, 179, 0);
+    VSIZE50-60_COLOR: rgb(251, 140, 0);
+    VSIZE60-70_COLOR: rgb(244, 81, 30);
+    VSIZE70-80_COLOR: rgb(109, 76, 65);
+    VSIZE80-90_COLOR: rgb(117, 117, 117);
+    VSIZE90-100_COLOR: rgb(84, 110, 122);
+    VSIZE100-125_COLOR: rgb(183, 28, 28);
+    VSIZE125-150_COLOR: rgb(136, 14, 79);
+    VSIZE150-175_COLOR: rgb(74, 20, 140);
+    VSIZE175-200_COLOR: rgb(49, 27, 146);
+    VSIZE200-250_COLOR: rgb(26, 35, 126);
+    VSIZE250-300_COLOR: rgb(13, 71, 161);
+    VSIZE300-350_COLOR: rgb(1, 87, 155);
+    VSIZE350-400_COLOR: rgb(0, 96, 100);
+    VSIZE400-500_COLOR: rgb(0, 77, 64);
+    VSIZE500-600_COLOR: rgb(27, 94, 32);
+    VSIZE600-700_COLOR: rgb(51, 105, 30);
+    VSIZE700-800_COLOR: rgb(130, 119, 23);
+}