add mempool size fee selection

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

@@ -25,6 +25,7 @@ import com.sparrowwallet.sparrow.control.*;
 import com.sparrowwallet.sparrow.event.*;
 import com.sparrowwallet.sparrow.io.*;
 import com.sparrowwallet.sparrow.net.ElectrumServer;
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
 import com.sparrowwallet.sparrow.net.VersionCheckService;
 import com.sparrowwallet.sparrow.preferences.PreferencesDialog;
 import com.sparrowwallet.sparrow.transaction.TransactionController;
@@ -68,6 +69,9 @@ import java.io.*;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.text.ParseException;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.temporal.ChronoUnit;
 import java.util.*;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -75,7 +79,7 @@ import java.util.stream.Collectors;
 public class AppController implements Initializable {
     private static final Logger log = LoggerFactory.getLogger(AppController.class);
 
-    private static final int SERVER_PING_PERIOD = 8 * 60 * 1000;
+    private static final int SERVER_PING_PERIOD = 1 * 60 * 1000;
     private static final int ENUMERATE_HW_PERIOD = 30 * 1000;
     private static final int RATES_PERIOD = 5 * 60 * 1000;
     private static final int VERSION_CHECK_PERIOD_HOURS = 24;
@@ -143,7 +147,7 @@ public class AppController implements Initializable {
 
     private static Map<Integer, Double> targetBlockFeeRates;
 
-    private static Map<Long, Long> feeRateHistogram;
+    private static final Map<Date, Set<MempoolRateSize>> mempoolHistogram = new TreeMap<>();
 
     private static Double minimumRelayFeeRate;
 
@@ -151,7 +155,7 @@ public class AppController implements Initializable {
 
     private static List<Device> devices;
 
-    private static Map<Address, BitcoinURI> payjoinURIs = new HashMap<>();
+    private static final Map<Address, BitcoinURI> payjoinURIs = new HashMap<>();
 
     @Override
     public void initialize(URL location, ResourceBundle resources) {
@@ -652,8 +656,17 @@ public class AppController implements Initializable {
         return targetBlockFeeRates;
     }
 
-    public static Map<Long, Long> getFeeRateHistogram() {
+    public static Map<Date, Set<MempoolRateSize>> getMempoolHistogram() {
-        return feeRateHistogram;
+        return mempoolHistogram;
+    }
+
+    private void addMempoolRateSizes(Set<MempoolRateSize> rateSizes) {
+        LocalDateTime dateMinute = LocalDateTime.now().truncatedTo(ChronoUnit.MINUTES);
+        if(mempoolHistogram.isEmpty()) {
+            mempoolHistogram.put(Date.from(dateMinute.minusMinutes(1).atZone(ZoneId.systemDefault()).toInstant()), rateSizes);
+        }
+
+        mempoolHistogram.put(Date.from(dateMinute.atZone(ZoneId.systemDefault()).toInstant()), rateSizes);
     }
 
     public static Double getMinimumRelayFeeRate() {
@@ -1435,7 +1448,7 @@ public class AppController implements Initializable {
     public void newConnection(ConnectionEvent event) {
         currentBlockHeight = event.getBlockHeight();
         targetBlockFeeRates = event.getTargetBlockFeeRates();
-        feeRateHistogram = event.getFeeRateHistogram();
+        addMempoolRateSizes(event.getMempoolRateSizes());
         minimumRelayFeeRate = event.getMinimumRelayFeeRate();
         String banner = event.getServerBanner();
         String status = "Connected to " + Config.get().getElectrumServer() + " at height " + event.getBlockHeight();
@@ -1460,7 +1473,7 @@ public class AppController implements Initializable {
     @Subscribe
     public void feesUpdated(FeeRatesUpdatedEvent event) {
         targetBlockFeeRates = event.getTargetBlockFeeRates();
-        feeRateHistogram = event.getFeeRateHistogram();
+        addMempoolRateSizes(event.getMempoolRateSizes());
     }
 
     @Subscribe

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

@@ -9,11 +9,11 @@ import javafx.scene.chart.XYChart;
 import java.util.Iterator;
 import java.util.Map;
 
-public class FeeRatesChart extends LineChart<String, Number> {
+public class BlockTargetFeeRatesChart extends LineChart<String, Number> {
     private XYChart.Series<String, Number> feeRateSeries;
     private Integer selectedTargetBlocks;
 
-    public FeeRatesChart(@NamedArg("xAxis") Axis<String> xAxis, @NamedArg("yAxis") Axis<Number> yAxis) {
+    public BlockTargetFeeRatesChart(@NamedArg("xAxis") Axis<String> xAxis, @NamedArg("yAxis") Axis<Number> yAxis) {
         super(xAxis, yAxis);
     }
 

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

@@ -0,0 +1,169 @@
+package com.sparrowwallet.sparrow.control;
+
+import com.sparrowwallet.sparrow.glyphfont.FontAwesome5;
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
+import com.sparrowwallet.sparrow.wallet.SendController;
+import javafx.application.Platform;
+import javafx.beans.NamedArg;
+import javafx.collections.FXCollections;
+import javafx.geometry.Pos;
+import javafx.scene.Cursor;
+import javafx.scene.Node;
+import javafx.scene.chart.*;
+import javafx.scene.control.Label;
+import javafx.scene.control.Tooltip;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.VBox;
+import javafx.util.Duration;
+import javafx.util.StringConverter;
+import org.controlsfx.glyphfont.Glyph;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class MempoolSizeFeeRatesChart extends StackedAreaChart<String, Number> {
+    private static final DateFormat dateFormatter = new SimpleDateFormat("HH:mm");
+
+    private Tooltip tooltip;
+
+    public MempoolSizeFeeRatesChart(@NamedArg("xAxis") Axis<String> xAxis, @NamedArg("yAxis") Axis<Number> yAxis) {
+        super(xAxis, yAxis);
+    }
+
+    public void initialize() {
+        setCreateSymbols(false);
+        setCursor(Cursor.CROSSHAIR);
+        setVerticalGridLinesVisible(false);
+        tooltip = new Tooltip();
+        tooltip.setShowDelay(Duration.ZERO);
+        tooltip.setHideDelay(Duration.ZERO);
+        tooltip.setShowDuration(Duration.INDEFINITE);
+        Platform.runLater(() -> {
+            Node node = this.lookup(".plot-content");
+            Tooltip.install(node, tooltip);
+        });
+    }
+
+    public void update(Map<Date, Set<MempoolRateSize>> mempoolRateSizes) {
+        getData().clear();
+        if(tooltip.isShowing()) {
+            tooltip.hide();
+        }
+
+        Map<Date, Set<MempoolRateSize>> periodRateSizes = getPeriodRateSizes(mempoolRateSizes);
+        List<String> categories = getCategories(periodRateSizes);
+
+        CategoryAxis categoryAxis = (CategoryAxis)getXAxis();
+        if(categoryAxis.getCategories() == null) {
+            categoryAxis.setCategories(FXCollections.observableArrayList(categories));
+        } else {
+            categoryAxis.getCategories().retainAll(categories);
+            categories.removeAll(categoryAxis.getCategories());
+            categoryAxis.getCategories().addAll(categories);
+        }
+
+        categoryAxis.setGapStartAndEnd(false);
+        categoryAxis.setOnMouseMoved(mouseEvent -> {
+            String category = categoryAxis.getValueForDisplay(mouseEvent.getX());
+            if(category != null) {
+                tooltip.setGraphic(new ChartTooltip(category, getData()));
+            }
+        });
+
+        NumberAxis numberAxis = (NumberAxis)getYAxis();
+        numberAxis.setTickLabelFormatter(new StringConverter<Number>() {
+            @Override
+            public String toString(Number object) {
+                long vSizeBytes = object.longValue();
+                return (vSizeBytes / (1000 * 1000)) + " MvB";
+            }
+
+            @Override
+            public Number fromString(String string) {
+                return null;
+            }
+        });
+
+        long previousFeeRate = 0;
+        for(Long feeRate : SendController.FEE_RATES_RANGE) {
+            XYChart.Series<String, Number> series = new XYChart.Series<>();
+            series.setName(feeRate + "+ vB");
+
+            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) {
+                        totalVSize += rateSize.getVSize();
+                    }
+                }
+
+                series.getData().add(new XYChart.Data<>(dateFormatter.format(date), totalVSize));
+            }
+
+            previousFeeRate = feeRate;
+            getData().add(series);
+        }
+
+        if(categories.iterator().hasNext()) {
+            tooltip.setGraphic(new ChartTooltip(categories.iterator().next(), getData()));
+            numberAxis.setTickLabelsVisible(true);
+            numberAxis.setOpacity(1);
+        } else {
+            numberAxis.setTickLabelsVisible(false);
+            numberAxis.setOpacity(0);
+        }
+    }
+
+    private Map<Date, Set<MempoolRateSize>> getPeriodRateSizes(Map<Date, Set<MempoolRateSize>> mempoolRateSizes) {
+        if(mempoolRateSizes.size() == 1) {
+            return mempoolRateSizes;
+        }
+
+        LocalDateTime period = LocalDateTime.now().minusHours(6);
+        return mempoolRateSizes.entrySet().stream().filter(entry -> {
+            LocalDateTime dateTime = entry.getKey().toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
+            return dateTime.isAfter(period);
+        }).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue,
+                (u, v) -> { throw new IllegalStateException("Duplicate dates"); },
+                TreeMap::new));
+    }
+
+    private List<String> getCategories(Map<Date, Set<MempoolRateSize>> mempoolHistogram) {
+        List<String> categories = new ArrayList<>();
+        for(Date date : mempoolHistogram.keySet()) {
+            categories.add(dateFormatter.format(date));
+        }
+
+        return categories;
+    }
+
+    private static class ChartTooltip extends VBox {
+        public ChartTooltip(String category, List<Series<String, Number>> seriesList) {
+            Label title = new Label("At " + category);
+            HBox titleBox = new HBox(title);
+            title.getStyleClass().add("tooltip-title");
+            getChildren().add(titleBox);
+
+            for(int i = seriesList.size() - 1; i >= 0; i--) {
+                Series<String, Number> series = seriesList.get(i);
+                for(XYChart.Data<String, Number> data : series.getData()) {
+                    if(data.getXValue().equals(category)) {
+                        double mvb = data.getYValue().doubleValue() / (1000 * 1000);
+                        if(mvb >= 0.01) {
+                            Label label = new Label(series.getName() + ": " + String.format("%.2f", mvb) + " MvB");
+                            Glyph circle = new Glyph(FontAwesome5.FONT_NAME, FontAwesome5.Glyph.CIRCLE);
+                            circle.getStyleClass().add("tooltip-series" + i);
+                            label.setGraphic(circle);
+                            getChildren().add(label);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

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

@@ -1,9 +1,11 @@
 package com.sparrowwallet.sparrow.event;
 
 import com.sparrowwallet.drongo.protocol.BlockHeader;
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 public class ConnectionEvent extends FeeRatesUpdatedEvent {
     private final List<String> serverVersion;
@@ -12,8 +14,8 @@ public class ConnectionEvent extends FeeRatesUpdatedEvent {
     private final BlockHeader blockHeader;
     private final Double minimumRelayFeeRate;
 
-    public ConnectionEvent(List<String> serverVersion, String serverBanner, int blockHeight, BlockHeader blockHeader, Map<Integer, Double> targetBlockFeeRates, Map<Long, Long> feeRateHistogram, Double minimumRelayFeeRate) {
+    public ConnectionEvent(List<String> serverVersion, String serverBanner, int blockHeight, BlockHeader blockHeader, Map<Integer, Double> targetBlockFeeRates, Set<MempoolRateSize> mempoolRateSizes, Double minimumRelayFeeRate) {
-        super(targetBlockFeeRates, feeRateHistogram);
+        super(targetBlockFeeRates, mempoolRateSizes);
         this.serverVersion = serverVersion;
         this.serverBanner = serverBanner;
         this.blockHeight = blockHeight;

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

@@ -0,0 +1,15 @@
+package com.sparrowwallet.sparrow.event;
+
+import com.sparrowwallet.sparrow.wallet.FeeRateSelection;
+
+public class FeeRateSelectionChangedEvent {
+    private final FeeRateSelection feeRateSelection;
+
+    public FeeRateSelectionChangedEvent(FeeRateSelection feeRateSelection) {
+        this.feeRateSelection = feeRateSelection;
+    }
+
+    public FeeRateSelection getFeeRateSelection() {
+        return feeRateSelection;
+    }
+}

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

@@ -1,21 +1,24 @@
 package com.sparrowwallet.sparrow.event;
 
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
+
 import java.util.Map;
+import java.util.Set;
 
 public class FeeRatesUpdatedEvent {
     private final Map<Integer, Double> targetBlockFeeRates;
-    private final Map<Long, Long> feeRateHistogram;
+    private final Set<MempoolRateSize> mempoolRateSizes;
 
-    public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Map<Long, Long> feeRateHistogram) {
+    public FeeRatesUpdatedEvent(Map<Integer, Double> targetBlockFeeRates, Set<MempoolRateSize> mempoolRateSizes) {
         this.targetBlockFeeRates = targetBlockFeeRates;
-        this.feeRateHistogram = feeRateHistogram;
+        this.mempoolRateSizes = mempoolRateSizes;
     }
 
     public Map<Integer, Double> getTargetBlockFeeRates() {
         return targetBlockFeeRates;
     }
 
-    public Map<Long, Long> getFeeRateHistogram() {
+    public Set<MempoolRateSize> getMempoolRateSizes() {
-        return feeRateHistogram;
+        return mempoolRateSizes;
     }
 }

src/main/java/com/sparrowwallet/sparrow/io/Config.java

@@ -4,6 +4,7 @@ import com.google.gson.*;
 import com.sparrowwallet.drongo.BitcoinUnit;
 import com.sparrowwallet.sparrow.Mode;
 import com.sparrowwallet.sparrow.Theme;
+import com.sparrowwallet.sparrow.wallet.FeeRateSelection;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -19,6 +20,7 @@ public class Config {
 
     private Mode mode;
     private BitcoinUnit bitcoinUnit;
+    private FeeRateSelection feeRateSelection;
     private Currency fiatCurrency;
     private ExchangeSource exchangeSource;
     private boolean groupByAddress = true;
@@ -98,6 +100,15 @@ public class Config {
         flush();
     }
 
+    public FeeRateSelection getFeeRateSelection() {
+        return feeRateSelection;
+    }
+
+    public void setFeeRateSelection(FeeRateSelection feeRateSelection) {
+        this.feeRateSelection = feeRateSelection;
+        flush();
+    }
+
     public Currency getFiatCurrency() {
         return fiatCurrency;
     }

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

@@ -610,8 +610,14 @@ public class ElectrumServer {
         }
     }
 
-    public Map<Long, Long> getFeeRateHistogram() throws ServerException {
+    public Set<MempoolRateSize> getMempoolRateSizes() throws ServerException {
-        return electrumServerRpc.getFeeRateHistogram(getTransport());
+        Map<Long, Long> feeRateHistogram = electrumServerRpc.getFeeRateHistogram(getTransport());
+        Set<MempoolRateSize> mempoolRateSizes = new TreeSet<>();
+        for(Long fee : feeRateHistogram.keySet()) {
+            mempoolRateSizes.add(new MempoolRateSize(fee, feeRateHistogram.get(fee)));
+        }
+
+        return mempoolRateSizes;
     }
 
     public Double getMinimumRelayFee() throws ServerException {
@@ -712,7 +718,7 @@ public class ElectrumServer {
     }
 
     public static class ConnectionService extends ScheduledService<FeeRatesUpdatedEvent> implements Thread.UncaughtExceptionHandler {
-        private static final int FEE_RATES_PERIOD = 10 * 60 * 1000;
+        private static final int FEE_RATES_PERIOD = 1 * 60 * 1000;
 
         private final boolean subscribe;
         private boolean firstCall = true;
@@ -764,7 +770,7 @@ public class ElectrumServer {
                         String banner = electrumServer.getServerBanner();
 
                         Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(SendController.TARGET_BLOCKS_RANGE);
-                        Map<Long, Long> feeRateHistogram = electrumServer.getFeeRateHistogram();
+                        Set<MempoolRateSize> mempoolRateSizes = electrumServer.getMempoolRateSizes();
                         feeRatesRetrievedAt = System.currentTimeMillis();
 
                         Double minimumRelayFeeRate = electrumServer.getMinimumRelayFee();
@@ -772,7 +778,7 @@ public class ElectrumServer {
                             blockTargetFeeRates.computeIfPresent(blockTarget, (blocks, feeRate) -> feeRate < minimumRelayFeeRate ? minimumRelayFeeRate : feeRate);
                         }
 
-                        return new ConnectionEvent(serverVersion, banner, tip.height, tip.getBlockHeader(), blockTargetFeeRates, feeRateHistogram, minimumRelayFeeRate);
+                        return new ConnectionEvent(serverVersion, banner, tip.height, tip.getBlockHeader(), blockTargetFeeRates, mempoolRateSizes, minimumRelayFeeRate);
                     } else {
                         if(reader.isAlive()) {
                             electrumServer.ping();
@@ -780,9 +786,9 @@ public class ElectrumServer {
                             long elapsed = System.currentTimeMillis() - feeRatesRetrievedAt;
                             if(elapsed > FEE_RATES_PERIOD) {
                                 Map<Integer, Double> blockTargetFeeRates = electrumServer.getFeeEstimates(SendController.TARGET_BLOCKS_RANGE);
-                                Map<Long, Long> feeRateHistogram = electrumServer.getFeeRateHistogram();
+                                Set<MempoolRateSize> mempoolRateSizes = electrumServer.getMempoolRateSizes();
                                 feeRatesRetrievedAt = System.currentTimeMillis();
-                                return new FeeRatesUpdatedEvent(blockTargetFeeRates, feeRateHistogram);
+                                return new FeeRatesUpdatedEvent(blockTargetFeeRates, mempoolRateSizes);
                             }
                         } else {
                             resetConnection();

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

@@ -0,0 +1,43 @@
+package com.sparrowwallet.sparrow.net;
+
+import java.util.Objects;
+
+public class MempoolRateSize implements Comparable<MempoolRateSize> {
+    private final long fee;
+    private final long vSize;
+
+    public MempoolRateSize(long fee, long vSize) {
+        this.fee = fee;
+        this.vSize = vSize;
+    }
+
+    public long getFee() {
+        return fee;
+    }
+
+    public long getVSize() {
+        return vSize;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if(this == o) {
+            return true;
+        }
+        if(o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        MempoolRateSize that = (MempoolRateSize) o;
+        return fee == that.fee;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(fee);
+    }
+
+    @Override
+    public int compareTo(MempoolRateSize other) {
+        return Long.compare(fee, other.fee);
+    }
+}

src/main/java/com/sparrowwallet/sparrow/preferences/GeneralPreferencesController.java

@@ -4,10 +4,12 @@ import com.sparrowwallet.drongo.BitcoinUnit;
 import com.sparrowwallet.sparrow.EventManager;
 import com.sparrowwallet.sparrow.control.UnlabeledToggleSwitch;
 import com.sparrowwallet.sparrow.event.BitcoinUnitChangedEvent;
+import com.sparrowwallet.sparrow.event.FeeRateSelectionChangedEvent;
 import com.sparrowwallet.sparrow.event.FiatCurrencySelectedEvent;
 import com.sparrowwallet.sparrow.event.VersionCheckStatusEvent;
 import com.sparrowwallet.sparrow.io.Config;
 import com.sparrowwallet.sparrow.io.ExchangeSource;
+import com.sparrowwallet.sparrow.wallet.FeeRateSelection;
 import javafx.beans.value.ChangeListener;
 import javafx.beans.value.ObservableValue;
 import javafx.fxml.FXML;
@@ -24,6 +26,9 @@ public class GeneralPreferencesController extends PreferencesDetailController {
     @FXML
     private ComboBox<BitcoinUnit> bitcoinUnit;
 
+    @FXML
+    private ComboBox<FeeRateSelection> feeRateSelection;
+
     @FXML
     private ComboBox<Currency> fiatCurrency;
 
@@ -63,6 +68,18 @@ public class GeneralPreferencesController extends PreferencesDetailController {
             EventManager.get().post(new BitcoinUnitChangedEvent(newValue));
         });
 
+        if(config.getFeeRateSelection() != null) {
+            feeRateSelection.setValue(config.getFeeRateSelection());
+        } else {
+            feeRateSelection.getSelectionModel().select(0);
+            config.setFeeRateSelection(FeeRateSelection.BLOCK_TARGET);
+        }
+
+        feeRateSelection.valueProperty().addListener((observable, oldValue, newValue) -> {
+            config.setFeeRateSelection(newValue);
+            EventManager.get().post(new FeeRateSelectionChangedEvent(newValue));
+        });
+
         if(config.getExchangeSource() != null) {
             exchangeSource.setValue(config.getExchangeSource());
         } else {

src/main/java/com/sparrowwallet/sparrow/preferences/PreferencesDialog.java

@@ -49,7 +49,7 @@ public class PreferencesDialog extends Dialog<Boolean> {
             }
 
             dialogPane.setPrefWidth(650);
-            dialogPane.setPrefHeight(500);
+            dialogPane.setPrefHeight(550);
 
             existingConnection = ElectrumServer.isConnected();
             setOnCloseRequest(event -> {

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

@@ -0,0 +1,20 @@
+package com.sparrowwallet.sparrow.wallet;
+
+public enum FeeRateSelection {
+    BLOCK_TARGET("Block Target"), MEMPOOL_SIZE("Mempool Size");
+
+    private final String name;
+
+    private FeeRateSelection(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+}

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

@@ -2,11 +2,8 @@ package com.sparrowwallet.sparrow.wallet;
 
 import com.google.common.eventbus.Subscribe;
 import com.sparrowwallet.drongo.BitcoinUnit;
-import com.sparrowwallet.drongo.address.Address;
 import com.sparrowwallet.drongo.address.InvalidAddressException;
-import com.sparrowwallet.drongo.address.P2PKHAddress;
 import com.sparrowwallet.drongo.protocol.Transaction;
-import com.sparrowwallet.drongo.protocol.TransactionOutput;
 import com.sparrowwallet.drongo.psbt.PSBT;
 import com.sparrowwallet.drongo.wallet.*;
 import com.sparrowwallet.sparrow.AppController;
@@ -17,6 +14,7 @@ import com.sparrowwallet.sparrow.event.*;
 import com.sparrowwallet.sparrow.io.Config;
 import com.sparrowwallet.sparrow.io.ExchangeSource;
 import com.sparrowwallet.sparrow.net.ElectrumServer;
+import com.sparrowwallet.sparrow.net.MempoolRateSize;
 import javafx.application.Platform;
 import javafx.beans.property.*;
 import javafx.beans.value.ChangeListener;
@@ -36,6 +34,7 @@ import org.controlsfx.validation.Validator;
 import org.controlsfx.validation.decoration.StyleClassValidationDecoration;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import tornadofx.control.Field;
 
 import java.io.IOException;
 import java.net.URL;
@@ -49,15 +48,25 @@ public class SendController extends WalletFormController implements Initializabl
     private static final Logger log = LoggerFactory.getLogger(SendController.class);
 
     public static final List<Integer> TARGET_BLOCKS_RANGE = List.of(1, 2, 3, 4, 5, 10, 25, 50, 100, 500);
+    public static final List<Long> FEE_RATES_RANGE = List.of(1L, 2L, 4L, 8L, 16L, 32L, 64L, 128L, 256L, 512L, 1024L);
 
     public static final double FALLBACK_FEE_RATE = 20000d / 1000;
 
     @FXML
     private TabPane paymentTabs;
 
+    @FXML
+    private Field targetBlocksField;
+
     @FXML
     private Slider targetBlocks;
 
+    @FXML
+    private Field feeRangeField;
+
+    @FXML
+    private Slider feeRange;
+
     @FXML
     private CopyableLabel feeRate;
 
@@ -71,7 +80,10 @@ public class SendController extends WalletFormController implements Initializabl
     private FiatLabel fiatFeeAmount;
 
     @FXML
-    private FeeRatesChart feeRatesChart;
+    private BlockTargetFeeRatesChart blockTargetFeeRatesChart;
+
+    @FXML
+    private MempoolSizeFeeRatesChart mempoolSizeFeeRatesChart;
 
     @FXML
     private TransactionDiagram transactionDiagram;
@@ -121,7 +133,7 @@ public class SendController extends WalletFormController implements Initializabl
 
             if(targetBlocksFeeRates != null) {
                 setFeeRate(targetBlocksFeeRates.get(target));
-                feeRatesChart.select(target);
+                blockTargetFeeRatesChart.select(target);
             } else {
                 feeRate.setText("Unknown");
             }
@@ -138,6 +150,19 @@ public class SendController extends WalletFormController implements Initializabl
         }
     };
 
+    private final ChangeListener<Number> feeRangeListener = new ChangeListener<>() {
+        @Override
+        public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
+            setFeeRate(getFeeRangeRate());
+            userFeeSet.set(false);
+            for(Tab tab : paymentTabs.getTabs()) {
+                PaymentController controller = (PaymentController)tab.getUserData();
+                controller.revalidate();
+            }
+            updateTransaction();
+        }
+    };
+
     private ValidationSupport validationSupport;
 
     @Override
@@ -180,6 +205,7 @@ public class SendController extends WalletFormController implements Initializabl
             revalidate(fee, feeListener);
         });
 
+        targetBlocksField.managedProperty().bind(targetBlocksField.visibleProperty());
         targetBlocks.setMin(0);
         targetBlocks.setMax(TARGET_BLOCKS_RANGE.size() - 1);
         targetBlocks.setMajorTickUnit(1);
@@ -198,18 +224,43 @@ public class SendController extends WalletFormController implements Initializabl
         });
         targetBlocks.valueProperty().addListener(targetBlocksListener);
 
-        feeRatesChart.initialize();
+        feeRangeField.managedProperty().bind(feeRangeField.visibleProperty());
+        feeRangeField.visibleProperty().bind(targetBlocksField.visibleProperty().not());
+        feeRange.setMin(0);
+        feeRange.setMax(FEE_RATES_RANGE.size() - 1);
+        feeRange.setMajorTickUnit(1);
+        feeRange.setMinorTickCount(0);
+        feeRange.setLabelFormatter(new StringConverter<Double>() {
+            @Override
+            public String toString(Double object) {
+                return Long.toString(FEE_RATES_RANGE.get(object.intValue()));
+            }
+
+            @Override
+            public Double fromString(String string) {
+                return null;
+            }
+        });
+        feeRange.valueProperty().addListener(feeRangeListener);
+
+        blockTargetFeeRatesChart.managedProperty().bind(blockTargetFeeRatesChart.visibleProperty());
+        blockTargetFeeRatesChart.initialize();
         Map<Integer, Double> targetBlocksFeeRates = getTargetBlocksFeeRates();
         if(targetBlocksFeeRates != null) {
-            feeRatesChart.update(targetBlocksFeeRates);
+            blockTargetFeeRatesChart.update(targetBlocksFeeRates);
         } else {
             feeRate.setText("Unknown");
         }
 
-        int defaultTarget = TARGET_BLOCKS_RANGE.get((TARGET_BLOCKS_RANGE.size() / 2) - 1);
+        mempoolSizeFeeRatesChart.managedProperty().bind(mempoolSizeFeeRatesChart.visibleProperty());
-        int index = TARGET_BLOCKS_RANGE.indexOf(defaultTarget);
+        mempoolSizeFeeRatesChart.visibleProperty().bind(blockTargetFeeRatesChart.visibleProperty().not());
-        targetBlocks.setValue(index);
+        mempoolSizeFeeRatesChart.initialize();
-        feeRatesChart.select(defaultTarget);
+        Map<Date, Set<MempoolRateSize>> mempoolHistogram = getMempoolHistogram();
+        if(mempoolHistogram != null) {
+            mempoolSizeFeeRatesChart.update(mempoolHistogram);
+        }
+
+        updateFeeRateSelection(Config.get().getFeeRateSelection());
 
         fee.setTextFormatter(new CoinTextFormatter());
         fee.textProperty().addListener(feeListener);
@@ -224,7 +275,7 @@ public class SendController extends WalletFormController implements Initializabl
         });
 
         userFeeSet.addListener((observable, oldValue, newValue) -> {
-            feeRatesChart.select(0);
+            blockTargetFeeRatesChart.select(0);
 
             Node thumb = getSliderThumb();
             if(thumb != null) {
@@ -405,6 +456,27 @@ public class SendController extends WalletFormController implements Initializabl
         return Collections.emptyList();
     }
 
+    private void updateFeeRateSelection(FeeRateSelection feeRateSelection) {
+        boolean blockTargetSelection = (feeRateSelection == FeeRateSelection.BLOCK_TARGET);
+        targetBlocksField.setVisible(blockTargetSelection);
+        blockTargetFeeRatesChart.setVisible(blockTargetSelection);
+        setDefaultFeeRate();
+        updateTransaction();
+    }
+
+    private void setDefaultFeeRate() {
+        if(targetBlocksField.isVisible()) {
+            int defaultTarget = TARGET_BLOCKS_RANGE.get((TARGET_BLOCKS_RANGE.size() / 2) - 1);
+            int index = TARGET_BLOCKS_RANGE.indexOf(defaultTarget);
+            targetBlocks.setValue(index);
+            blockTargetFeeRatesChart.select(defaultTarget);
+            setFeeRate(getTargetBlocksFeeRates().get(getTargetBlocks()));
+        } else {
+            feeRange.setValue(5.0);
+            setFeeRate(getFeeRangeRate());
+        }
+    }
+
     private Long getFeeValueSats() {
         return getFeeValueSats(feeAmountUnit.getSelectionModel().getSelectedItem());
     }
@@ -450,7 +522,7 @@ public class SendController extends WalletFormController implements Initializabl
         targetBlocks.valueProperty().removeListener(targetBlocksListener);
         int index = TARGET_BLOCKS_RANGE.indexOf(target);
         targetBlocks.setValue(index);
-        feeRatesChart.select(target);
+        blockTargetFeeRatesChart.select(target);
         targetBlocks.valueProperty().addListener(targetBlocksListener);
     }
 
@@ -465,8 +537,16 @@ public class SendController extends WalletFormController implements Initializabl
         return retrievedFeeRates;
     }
 
+    private Double getFeeRangeRate() {
+        return Math.pow(2.0, feeRange.getValue());
+    }
+
     public Double getFeeRate() {
-        return getTargetBlocksFeeRates().get(getTargetBlocks());
+        if(targetBlocksField.isVisible()) {
+            return getTargetBlocksFeeRates().get(getTargetBlocks());
+        } else {
+            return getFeeRangeRate();
+        }
     }
 
     private Double getMinimumFeeRate() {
@@ -475,6 +555,10 @@ public class SendController extends WalletFormController implements Initializabl
         return Math.max(minRate, Transaction.DUST_RELAY_TX_FEE);
     }
 
+    private Map<Date, Set<MempoolRateSize>> getMempoolHistogram() {
+        return AppController.getMempoolHistogram();
+    }
+
     public boolean isInsufficientFeeRate() {
         return walletTransactionProperty.get() != null && walletTransactionProperty.get().getFeeRate() < AppController.getMinimumRelayFeeRate();
     }
@@ -662,9 +746,17 @@ public class SendController extends WalletFormController implements Initializabl
 
     @Subscribe
     public void feeRatesUpdated(FeeRatesUpdatedEvent event) {
-        feeRatesChart.update(event.getTargetBlockFeeRates());
+        blockTargetFeeRatesChart.update(event.getTargetBlockFeeRates());
-        feeRatesChart.select(getTargetBlocks());
+        blockTargetFeeRatesChart.select(getTargetBlocks());
-        setFeeRate(event.getTargetBlockFeeRates().get(getTargetBlocks()));
+        mempoolSizeFeeRatesChart.update(getMempoolHistogram());
+        if(targetBlocksField.isVisible()) {
+            setFeeRate(event.getTargetBlockFeeRates().get(getTargetBlocks()));
+        }
+    }
+
+    @Subscribe
+    public void feeRateSelectionChanged(FeeRateSelectionChangedEvent event) {
+        updateFeeRateSelection(event.getFeeRateSelection());
     }
 
     @Subscribe

src/main/resources/com/sparrowwallet/sparrow/preferences/general.fxml

@@ -15,6 +15,7 @@
 <?import com.sparrowwallet.sparrow.io.ExchangeSource?>
 <?import com.sparrowwallet.sparrow.control.UnlabeledToggleSwitch?>
 <?import com.sparrowwallet.sparrow.control.HelpLabel?>
+<?import com.sparrowwallet.sparrow.wallet.FeeRateSelection?>
 
 <GridPane hgap="10.0" vgap="10.0" stylesheets="@preferences.css, @../general.css" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.sparrowwallet.sparrow.preferences.GeneralPreferencesController">
     <padding>
@@ -41,6 +42,17 @@
                 </ComboBox>
                 <HelpLabel helpText="Display unit for bitcoin amounts.\nAuto displays amounts over 1 BTC in BTC, and amounts under that in satoshis."/>
             </Field>
+            <Field text="Fee rate selection:">
+                <ComboBox fx:id="feeRateSelection">
+                    <items>
+                        <FXCollections fx:factory="observableArrayList">
+                            <FeeRateSelection fx:constant="BLOCK_TARGET" />
+                            <FeeRateSelection fx:constant="MEMPOOL_SIZE" />
+                        </FXCollections>
+                    </items>
+                </ComboBox>
+                <HelpLabel helpText="Fee rate selection can be done either by estimating the number of blocks until a transaction is mined, or examining the current size of the mempool."/>
+            </Field>
         </Fieldset>
         <Fieldset inputGrow="SOMETIMES" text="Fiat" styleClass="wideLabelFieldSet">
             <Field text="Currency:">

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

@@ -39,7 +39,7 @@
     -fx-max-width: 76px;
 }
 
-#feeRatesChart {
+.feeRatesChart {
     -fx-max-width: 335px;
     -fx-max-height: 130px;
 }
@@ -107,4 +107,19 @@
 
 #transactionDiagram .utxo-label:hover .button .label .text {
     -fx-fill: -fx-text-base-color;
-}
+}
+
+.tooltip-title {
+    -fx-alignment: center;
+    -fx-font-size: 12px;
+    -fx-padding: 0 0 5 0;
+}
+
+.tooltip-series0 { -fx-text-fill: CHART_COLOR_1; }
+.tooltip-series1 { -fx-text-fill: CHART_COLOR_2; }
+.tooltip-series2 { -fx-text-fill: CHART_COLOR_3; }
+.tooltip-series3 { -fx-text-fill: CHART_COLOR_4; }
+.tooltip-series4 { -fx-text-fill: CHART_COLOR_5; }
+.tooltip-series5 { -fx-text-fill: CHART_COLOR_6; }
+.tooltip-series6 { -fx-text-fill: CHART_COLOR_7; }
+.tooltip-series7 { -fx-text-fill: CHART_COLOR_8; }

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

@@ -14,13 +14,14 @@
 <?import javafx.geometry.Insets?>
 <?import com.sparrowwallet.sparrow.control.CopyableLabel?>
 <?import javafx.collections.FXCollections?>
-<?import com.sparrowwallet.sparrow.control.FeeRatesChart?>
+<?import com.sparrowwallet.sparrow.control.BlockTargetFeeRatesChart?>
 <?import javafx.scene.chart.CategoryAxis?>
 <?import javafx.scene.chart.NumberAxis?>
 <?import com.sparrowwallet.sparrow.control.TransactionDiagram?>
 <?import com.sparrowwallet.drongo.BitcoinUnit?>
 <?import com.sparrowwallet.sparrow.control.FiatLabel?>
 <?import org.controlsfx.glyphfont.Glyph?>
+<?import com.sparrowwallet.sparrow.control.MempoolSizeFeeRatesChart?>
 
 <BorderPane stylesheets="@send.css, @wallet.css, @../script.css, @../general.css" styleClass="wallet-pane" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.sparrowwallet.sparrow.wallet.SendController">
     <center>
@@ -49,9 +50,12 @@
                 </BorderPane>
                 <Form GridPane.columnIndex="0" GridPane.rowIndex="1">
                     <Fieldset inputGrow="SOMETIMES" text="Fee">
-                        <Field text="Block target">
+                        <Field fx:id="targetBlocksField" text="Block target">
                             <Slider fx:id="targetBlocks" snapToTicks="true" showTickLabels="true" showTickMarks="true" />
                         </Field>
+                        <Field fx:id="feeRangeField" text="Range:">
+                            <Slider fx:id="feeRange" snapToTicks="false" showTickLabels="true" showTickMarks="true" />
+                        </Field>
                         <Field fx:id="feeRateField" text="Rate:">
                             <CopyableLabel fx:id="feeRate" />
                         </Field>
@@ -71,14 +75,22 @@
                     </Fieldset>
                 </Form>
                 <AnchorPane GridPane.columnIndex="1" GridPane.rowIndex="1" GridPane.columnSpan="2">
-                    <FeeRatesChart fx:id="feeRatesChart" legendVisible="false" AnchorPane.topAnchor="10" AnchorPane.leftAnchor="20" animated="false">
+                    <BlockTargetFeeRatesChart fx:id="blockTargetFeeRatesChart" styleClass="feeRatesChart" legendVisible="false" AnchorPane.topAnchor="10" AnchorPane.leftAnchor="20" animated="false">
                         <xAxis>
                             <CategoryAxis side="BOTTOM" />
                         </xAxis>
                         <yAxis>
                             <NumberAxis side="LEFT" />
                         </yAxis>
-                    </FeeRatesChart>
+                    </BlockTargetFeeRatesChart>
+                    <MempoolSizeFeeRatesChart fx:id="mempoolSizeFeeRatesChart" styleClass="feeRatesChart" legendVisible="false" AnchorPane.topAnchor="10" AnchorPane.leftAnchor="20" animated="false">
+                        <xAxis>
+                            <CategoryAxis side="BOTTOM" />
+                        </xAxis>
+                        <yAxis>
+                            <NumberAxis side="LEFT" />
+                        </yAxis>
+                    </MempoolSizeFeeRatesChart>
                 </AnchorPane>
             </GridPane>
             <AnchorPane>