Fixed bug where jitter was switched with timestamp-diff in log output

README.md

@@ -94,20 +94,21 @@ pertains to. If a message has no such context then the IP column will be empty:
 There are 3 kinds of measurements:
 
 * ping (delta receive) - delta between receiving heartbeats
-* jitter (delta send) - delta between sending heartbeats
-* timestamp delta - delta between remotely recorded sent timestamp and locally recorded receive time
+* jitter (delta send) - the time that has passed between sending consecutive pings.
+* timestamp delta - delta between remotely recorded timestamp when ping
+  was generated and a locally recorded timestamp when it was received.
 
 Meshmonitor will print histograms of each of the three tracked values. All of these values need to be interpreted with
 the `--ping` interval in mind (default 5ms) that is included in the measurement values. The values that are printed are
 max, mean, and percentiles: 99th, 99.9th, and 99.99th:
 
 ```console
-[               ] --------receive-(ms)--------- ---------delta-(ms)---------- ---------send-(ms)-----------
-[               ]   Max  Mean    99  99.9 99.99|  Max  Mean    99  99.9 99.99|  Max  Mean    99  99.9 99.99
-[   172.31.10.72]   5.2   5.1   5.1   5.2   5.2|  0.2   0.0   0.0   0.1   0.2|  5.1   5.1   5.1   5.1   5.1
-[    172.31.14.3]   5.3   5.1   5.1   5.1   5.3|  0.4   0.2   0.2   0.2   0.4|  5.8   5.1   5.1   5.5   5.8
-[   172.31.9.146]   5.1   5.1   5.1   5.1   5.1|  5.1   2.6   5.0   5.1   5.1|  5.1   5.1   5.1   5.1   5.1
-[   172.31.5.177]   5.1   5.1   5.1   5.1   5.1|  5.2   2.8   5.2   5.2   5.2|  5.1   5.1   5.1   5.1   5.1
+09:08:55 [               ] ----------ping-(ms)---------- ---------jitter-(ms)--------- ----timestamp-diff-(ms)------
+09:08:55 [               ]   Max  Mean    99  99.9 99.99|  Max  Mean    99  99.9 99.99 |  Max  Mean    99  99.9 99.99
+09:08:55 [   172.31.10.72]   5.2   5.1   5.1   5.2   5.2|  5.1   5.1   5.1   5.1   5.1 |  0.2   0.0   0.0   0.1   0.2
+09:08:55 [    172.31.14.3]   5.3   5.1   5.1   5.1   5.3|  5.8   5.1   5.1   5.5   5.8 |  0.4   0.2   0.2   0.2   0.4
+09:08:55 [   172.31.9.146]   5.1   5.1   5.1   5.1   5.1|  5.1   5.1   5.1   5.1   5.1 |  5.1   2.6   5.0   5.1   5.1
+09:08:55 [   172.31.5.177]   5.1   5.1   5.1   5.1   5.1|  5.1   5.1   5.1   5.1   5.1 |  5.2   2.8   5.2   5.2   5.2
 ```
 
 Measurements exceeding `--threshold` (default 20ms) will be printed in yellow. Those that exceed 1 second will be printed in
@@ -128,7 +129,7 @@ using [GraalVM Community Edition](https://github.com/graalvm/graalvm-ce-builds/r
 dependencies and can be run as is.
 
 A pure Java version in jar form (meshmonitor.jar) is also available. The Java version should work on 
-any platform with Java 17 or later installed (although it has only been tested on Linux).
+any platform with Java 8 or later installed (although it has only been tested on Linux).
 
 # Using Meshmonitor
 
@@ -230,11 +231,11 @@ Use the following command to run meshmonitor from the jar file:
 java -jar meshmonitor.jar <ARGS> 
 ```
 
-It requires at least Java 17 to run.
+Java 8 is enough run it but Java 11 is required to build and execute tests.
 
 ## Building
 
-Java SDK is required to build and test the Meshmonitor. Version 17 or above.
+Java SDK is required to build and test the Meshmonitor. Version 11 or above.
 Maven is used as a build system but does not need to be installed locally.
 
 The `mvnw` script (or `mvnw.cmd` on Windows) is used to bootstrap the build

pom.xml

@@ -21,11 +21,11 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 
-        <maven.compiler.source>17</maven.compiler.source>
-        <maven.compiler.target>17</maven.compiler.target>
+        <maven.compiler.source>8</maven.compiler.source>
+        <maven.compiler.target>8</maven.compiler.target>
 
-        <maven.compiler.testSource>17</maven.compiler.testSource>
-        <maven.compiler.testTarget>17</maven.compiler.testTarget>
+        <maven.compiler.testSource>11</maven.compiler.testSource>
+        <maven.compiler.testTarget>11</maven.compiler.testTarget>
 
         <imageName>meshmonitor</imageName>
         <mainClass>org.voltdb.meshmonitor.cli.MeshMonitorCommand</mainClass>

src/main/java/org/voltdb/meshmonitor/ConsoleLogger.java

@@ -69,14 +69,14 @@ private void log(String hostAddress, LogLevel logLevel, String message, Object..
         String colourfulDateTime = CommandLine.Help.Ansi.AUTO.string(String.format("@|%s %s|@", logLevel, dateTime));
         String colourfulHostAddress = CommandLine.Help.Ansi.AUTO.string(String.format("@|%s [%15s]|@", logLevel, hostAddress));
 
-        out.println(colourfulDateTime + " " + colourfulHostAddress + " " + message.formatted(args));
+        out.println(colourfulDateTime + " " + colourfulHostAddress + " " + String.format(message, args));
     }
 
     public void debug(InetSocketAddress socketAddress, String format, Object... args) {
         String hostAddress = socketAddress.getAddress().getHostAddress();
 
         if (enableDebugLogging) {
-            log(hostAddress, LogLevel.INFO, format.formatted(args));
+            log(hostAddress, LogLevel.INFO, String.format(format, args));
         }
     }
 

src/main/java/org/voltdb/meshmonitor/GitPropertiesVersionProvider.java

@@ -59,15 +59,15 @@ public String getSimpleVersion() {
             String maybeCommitId = Objects.toString(properties.get(GIT_COMMIT_ID_PROPERTY), "");
 
             StringBuilder version = new StringBuilder();
-            if (!maybeTags.isBlank()) {
+            if (!maybeTags.trim().isEmpty()) {
                 version.append(maybeTags);
-            } else if (!maybeCommitId.isBlank()) {
+            } else if (!maybeCommitId.trim().isEmpty()) {
                 version.append(maybeCommitId);
             } else {
                 version.append(VERSION_UNKNOWN);
             }
 
-            if (!maybeBuildTime.isBlank()) {
+            if (!maybeBuildTime.trim().isEmpty()) {
                 version.append(" built on ").append(maybeBuildTime);
             }
 

src/main/java/org/voltdb/meshmonitor/HistogramLogger.java

@@ -25,11 +25,11 @@ public void printResults(Monitor monitor, long minHiccupSize) {
         MeshMonitorTimings currentTimings = monitor.getTimings();
         InetSocketAddress remoteId = monitor.getRemoteId();
 
-        String receive = printAndReset(currentTimings.receiveHistogram(), minHiccupSize);
-        String delta = printAndReset(currentTimings.deltaHistogram(), minHiccupSize);
-        String send = printAndReset(currentTimings.sendHistogram(), minHiccupSize);
+        String ping = printAndReset(currentTimings.pingHistogram(), minHiccupSize);
+        String jitter = printAndReset(currentTimings.jitterHistogram(), minHiccupSize);
+        String timestampDiff = printAndReset(currentTimings.timestampDeltaHistogram(), minHiccupSize);
 
-        consoleLogger.log(remoteId, receive + "|" + delta + "|" + send);
+        consoleLogger.log(remoteId, ping + "|" + jitter + "|" + timestampDiff);
     }
 
     private String printAndReset(HistogramWithDelta histogram, long minHiccupSize) {
@@ -53,11 +53,11 @@ private String format(Histogram deltaHistogram, long minHiccupSizeMicroseconds)
 
     private String getFormatWithColours(double value, double minHiccupSize) {
         if (value > 999.9) {
-            String formatted = "%4.1fs".formatted(value / 1000.0);
+            String formatted = String.format("%4.1fs", value / 1000.0);
             return CommandLine.Help.Ansi.AUTO.string("@|bold,red " + formatted + "|@");
         }
 
-        String formatted = "%5.1f".formatted(value);
+        String formatted = String.format("%5.1f", value);
         if (value > minHiccupSize) {
             return CommandLine.Help.Ansi.AUTO.string("@|bold,yellow " + formatted + "|@");
         }

src/main/java/org/voltdb/meshmonitor/MeshMonitorTimings.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 Volt Active Data Inc.
+ * Copyright (C) 2024-2025 Volt Active Data Inc.
  *
  * Use of this source code is governed by an MIT
  * license that can be found in the LICENSE file or at
@@ -9,25 +9,37 @@
 
 import org.HdrHistogram.SynchronizedHistogram;
 
-public record MeshMonitorTimings(
-        HistogramWithDelta receiveHistogram,
-        HistogramWithDelta sendHistogram,
-        HistogramWithDelta deltaHistogram) {
+import java.util.Objects;
+
+public final class MeshMonitorTimings {
 
     public static final int NUMBER_OF_SIGNIFICANT_VALUE_DIGITS = 3;
     public static final long HIGHEST_TRACKABLE_VALUE = 24 * 60 * 60 * 1000 * 1000L;
 
+    private final HistogramWithDelta pingHistogram;
+    private final HistogramWithDelta jitterHistogram;
+    private final HistogramWithDelta timestampDeltaHistogram;
+
+    public MeshMonitorTimings(
+            HistogramWithDelta pingHistogram,
+            HistogramWithDelta jitterHistogram,
+            HistogramWithDelta timestampDeltaHistogram) {
+        this.pingHistogram = pingHistogram;
+        this.jitterHistogram = jitterHistogram;
+        this.timestampDeltaHistogram = timestampDeltaHistogram;
+    }
+
     public void pingReceived(long now, long lastReceiveTime, long timestampFromRemoteHost, long pingInterval) {
         long valueToRecord = now - lastReceiveTime;
-        receiveHistogram.recordValueWithExpectedInterval(valueToRecord, pingInterval);
+        pingHistogram.recordValueWithExpectedInterval(valueToRecord, pingInterval);
 
         // Abs because clocks can be slightly out of sync...
         valueToRecord = Math.abs(now - timestampFromRemoteHost);
-        deltaHistogram.recordValueWithExpectedInterval(valueToRecord, pingInterval);
+        timestampDeltaHistogram.recordValueWithExpectedInterval(valueToRecord, pingInterval);
     }
 
     public void trackWakeupJitter(long observedInterval, long expectedInterval) {
-        sendHistogram.recordValueWithExpectedInterval(observedInterval, expectedInterval);
+        jitterHistogram.recordValueWithExpectedInterval(observedInterval, expectedInterval);
     }
 
     private static SynchronizedHistogram defaultHistogram() {
@@ -36,9 +48,45 @@ private static SynchronizedHistogram defaultHistogram() {
 
     public static MeshMonitorTimings createDefault(ConsoleLogger logger) {
         return new MeshMonitorTimings(
-                new HistogramWithDelta(logger, "receive", defaultHistogram()),
-                new HistogramWithDelta(logger, "send", defaultHistogram()),
-                new HistogramWithDelta(logger, "delta", defaultHistogram())
+                new HistogramWithDelta(logger, "ping", defaultHistogram()),
+                new HistogramWithDelta(logger, "jitter", defaultHistogram()),
+                new HistogramWithDelta(logger, "timestamp delta", defaultHistogram())
         );
     }
+
+    public HistogramWithDelta pingHistogram() {
+        return pingHistogram;
+    }
+
+    public HistogramWithDelta jitterHistogram() {
+        return jitterHistogram;
+    }
+
+    public HistogramWithDelta timestampDeltaHistogram() {
+        return timestampDeltaHistogram;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) return true;
+        if (obj == null || obj.getClass() != this.getClass())
+            return false;
+        MeshMonitorTimings that = (MeshMonitorTimings) obj;
+        return Objects.equals(this.pingHistogram, that.pingHistogram) &&
+               Objects.equals(this.jitterHistogram, that.jitterHistogram) &&
+               Objects.equals(this.timestampDeltaHistogram, that.timestampDeltaHistogram);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(pingHistogram, jitterHistogram, timestampDeltaHistogram);
+    }
+
+    @Override
+    public String toString() {
+        return "MeshMonitorTimings[" +
+               "pingHistogram=" + pingHistogram + ", " +
+               "jitterHistogram=" + jitterHistogram + ", " +
+               "timestampDeltaHistogram=" + timestampDeltaHistogram + ']';
+    }
 }

src/main/java/org/voltdb/meshmonitor/ServerManager.java

@@ -12,6 +12,7 @@
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public class ServerManager {
 
@@ -30,14 +31,14 @@ public ServerManager(ConsoleLogger consoleLogger, MonitorFactory monitorFactory,
     public synchronized List<Monitor> getMonitors() {
         return monitors.stream()
                 .filter(Monitor::isRunning)
-                .toList();
+                .collect(Collectors.toList());
     }
 
     public synchronized List<InetSocketAddress> getConnections() {
         return monitors.stream()
                 .filter(Monitor::isRunning)
                 .map(Monitor::getRemoteId)
-                .toList();
+                .collect(Collectors.toList());
     }
 
     public synchronized boolean createNewMonitorIfNotAlreadyPresent(SocketChannel channel, MeshMonitor meshMonitor, InetSocketAddress remoteId) {

src/main/java/org/voltdb/meshmonitor/cli/MeshMonitorCommand.java

@@ -121,14 +121,17 @@ public Integer call() {
 
         System.out.println(
                 CommandLine.Help.Ansi.AUTO.string(
-                        """
-                                @|green      __  ___          __                          _ __           \s
-                                    /  |/  /__  _____/ /_  ____ ___  ____  ____  (_) /_____  _____
-                                   / /|_/ / _ \\/ ___/ __ \\/ __ `__ \\/ __ \\/ __ \\/ / __/ __ \\/ ___/
-                                  / /  / /  __(__  ) / / / / / / / / /_/ / / / / / /_/ /_/ / /   \s
-                                 /_/  /_/\\___/____/_/ /_/_/ /_/ /_/\\____/_/ /_/_/\\__/\\____/_/ \s
-                                 |@                            %s
-                                """.formatted(new GitPropertiesVersionProvider().getSimpleVersion())));
+                        String.format(
+                                "@|green      __  ___          __                          _ __            \n" +
+                                "    /  |/  /__  _____/ /_  ____ ___  ____  ____  (_) /_____  _____\n" +
+                                "   / /|_/ / _ \\/ ___/ __ \\/ __ `__ \\/ __ \\/ __ \\/ / __/ __ \\/ ___/\n" +
+                                "  / /  / /  __(__  ) / / / / / / / / /_/ / / / / / /_/ /_/ / /    \n" +
+                                " /_/  /_/\\___/____/_/ /_/_/ /_/ /_/\\____/_/ /_/_/\\__/\\____/_/  \n" +
+                                " |@                            %s\n",
+                                new GitPropertiesVersionProvider().getSimpleVersion()
+                        )
+                )
+        );
 
         ConsoleLogger consoleLogger = new ConsoleLogger(spec.commandLine().getOut(), enableDebugLogging);
         ServerManager serverManager = new ServerManager(consoleLogger, Monitor::new, Duration.ofMillis(pingIntervalMilliseconds));

src/main/java/org/voltdb/meshmonitor/metrics/MonitorStatsPrinter.java

@@ -24,21 +24,21 @@ public void print(StringBuilder output, Monitor monitor) {
         MeshMonitorTimings timings = monitor.getTimings();
         InetSocketAddress remoteId = monitor.getRemoteId();
 
-        timings.receiveHistogram().getCumulativeHistogram(histogram ->
+        timings.pingHistogram().getCumulativeHistogram(histogram ->
                 histogramPrinter.printHistogram(output,
                         histogram,
                         remoteId,
                         "receive_seconds")
         );
 
-        timings.deltaHistogram().getCumulativeHistogram(histogram ->
+        timings.timestampDeltaHistogram().getCumulativeHistogram(histogram ->
                 histogramPrinter.printHistogram(output,
                         histogram,
                         remoteId,
                         "delta_seconds")
         );
 
-        timings.sendHistogram().getCumulativeHistogram(histogram -> {
+        timings.jitterHistogram().getCumulativeHistogram(histogram -> {
             histogramPrinter.printHistogram(output,
                     histogram,
                     remoteId,

src/test/java/org/voltdb/meshmonitor/GitPropertiesVersionProviderTest.java

@@ -22,48 +22,36 @@ public class GitPropertiesVersionProviderTest {
     static Stream<Arguments> variousPropertiesContents() {
         return Stream.of(
                 Arguments.of(
-                        """
-                                git.tags=v1.0
-                                git.build.time=2024-01-01
-                                git.commit.id.abbrev=abc123
-                                """,
+                        "git.tags=v1.0\n" +
+                        "git.build.time=2024-01-01\n" +
+                        "git.commit.id.abbrev=abc123\n",
                         "version v1.0 built on 2024-01-01"
                 ),
                 Arguments.of(
-                        """
-                                git.tags=
-                                git.build.time=2024-01-01
-                                git.commit.id.abbrev=abc123
-                                """,
+                        "git.tags=\n" +
+                        "git.build.time=2024-01-01\n" +
+                        "git.commit.id.abbrev=abc123\n",
                         "version abc123 built on 2024-01-01"
                 ),
                 Arguments.of(
-                        """
-                                git.tags=
-                                git.build.time=2024-01-01
-                                git.commit.id.abbrev=
-                                """,
+                        "git.tags=\n" +
+                        "git.build.time=2024-01-01\n" +
+                        "git.commit.id.abbrev=\n",
                         "version unknown built on 2024-01-01"
                 ),
                 Arguments.of(
-                        """
-                                git.tags=
-                                git.build.time=
-                                git.commit.id.abbrev=
-                                """,
+                        "git.tags=\n" +
+                        "git.build.time=\n" +
+                        "git.commit.id.abbrev=\n",
                         "version unknown"
                 ),
                 Arguments.of(
-                        """
-                                git.build.time=2024-01-01
-                                git.commit.id.abbrev=abc123
-                                """,
+                        "git.build.time=2024-01-01\n" +
+                        "git.commit.id.abbrev=abc123\n",
                         "version abc123 built on 2024-01-01"
                 ),
                 Arguments.of(
-                        """
-                                git.build.time=2024-01-01
-                                """,
+                        "git.build.time=2024-01-01\n",
                         "version unknown built on 2024-01-01"
                 ),
                 Arguments.of(