Implement handshake request metrics

src/main/java/ru/ruscalworld/fabricexporter/FabricExporter.java

@@ -7,12 +7,12 @@ import net.minecraft.server.MinecraftServer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import ru.ruscalworld.fabricexporter.config.MainConfig;
-import ru.ruscalworld.fabricexporter.metrics.*;
 
 import java.io.IOException;
-import java.util.Timer;
 
 public class FabricExporter implements ModInitializer {
+    private static FabricExporter instance;
+
     private MinecraftServer server;
     private MainConfig config;
     private HTTPServer httpServer;
@@ -50,6 +50,8 @@ public class FabricExporter implements ModInitializer {
             this.getHttpServer().stop();
             this.getMetricRegistry().getTimer().cancel();
         });
+
+        instance = this;
     }
 
     public static Logger getLogger() {
@@ -87,4 +89,8 @@ public class FabricExporter implements ModInitializer {
     private void setMetricRegistry(MetricRegistry metricRegistry) {
         this.metricRegistry = metricRegistry;
     }
+
+    public static FabricExporter getInstance() {
+        return instance;
+    }
 }

src/main/java/ru/ruscalworld/fabricexporter/MetricRegistry.java

@@ -1,16 +1,20 @@
 package ru.ruscalworld.fabricexporter;
 
 import io.prometheus.client.Collector;
+import io.prometheus.client.Counter;
+import io.prometheus.client.SimpleCollector;
 import ru.ruscalworld.fabricexporter.config.MainConfig;
 import ru.ruscalworld.fabricexporter.metrics.*;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Timer;
 
 public class MetricRegistry {
     private final FabricExporter exporter;
     private final List<Metric> metrics = new ArrayList<>();
+    private final HashMap<String, Collector> customMetrics = new HashMap<>();
     private final Timer timer;
 
     public MetricRegistry(FabricExporter exporter) {
@@ -32,25 +36,36 @@ public class MetricRegistry {
         this.registerMetric(new TotalLoadedChunks());
         this.registerMetric(new TicksPerSecond());
         this.registerMetric(new MillisPerTick());
+
+        this.registerCustomMetric("handshakes", new Counter.Builder()
+                .name(getMetricName("handshakes"))
+                .help("Amount of handshake requests")
+                .labelNames("type")
+        );
     }
 
     public void registerMetric(Metric metric) {
         MainConfig config = this.getExporter().getConfig();
         if (metric instanceof SparkMetric && !config.shouldUseSpark()) return;
-        if (!this.isEnabled(metric.getName())) return;
+        if (this.isDisabled(metric.getName())) return;
 
         metric.getGauge().register();
         this.metrics.add(metric);
     }
 
-    public void registerCustomMetric(String name, Collector collector) {
+    public void registerCustomMetric(String name, SimpleCollector.Builder<?, ?> collector) {
-        if (this.isEnabled(name)) collector.register();
+        if (this.isDisabled(name)) return;
+        this.getCustomMetrics().put(name, collector.register());
     }
 
-    public boolean isEnabled(String name) {
+    public boolean isDisabled(String name) {
         MainConfig config = this.getExporter().getConfig();
         String property = "enable-" + name.replace("_", "-");
-        return config.getProperties().getProperty(property, "true").equals("true");
+        return !config.getProperties().getProperty(property, "true").equals("true");
+    }
+
+    public static String getMetricName(String name) {
+        return "minecraft_" + name;
     }
 
     public List<Metric> getMetrics() {
@@ -64,4 +79,8 @@ public class MetricRegistry {
     public Timer getTimer() {
         return timer;
     }
+
+    public HashMap<String, Collector> getCustomMetrics() {
+        return customMetrics;
+    }
 }

src/main/java/ru/ruscalworld/fabricexporter/metrics/Metric.java

@@ -2,6 +2,7 @@ package ru.ruscalworld.fabricexporter.metrics;
 
 import io.prometheus.client.Gauge;
 import ru.ruscalworld.fabricexporter.FabricExporter;
+import ru.ruscalworld.fabricexporter.MetricRegistry;
 
 public abstract class Metric {
     private final Gauge gauge;
@@ -10,7 +11,7 @@ public abstract class Metric {
     public Metric(String name, String help, String... labels) {
         this.name = name;
         this.gauge = new Gauge.Builder()
-                .name("minecraft_" + name)
+                .name(MetricRegistry.getMetricName(name))
                 .help(help)
                 .labelNames(labels)
                 .create();

src/main/java/ru/ruscalworld/fabricexporter/mixin/ServerHandshakeNetworkHandlerMixin.java

@@ -0,0 +1,24 @@
+package ru.ruscalworld.fabricexporter.mixin;
+
+import io.prometheus.client.Collector;
+import io.prometheus.client.Counter;
+import net.minecraft.network.packet.c2s.handshake.HandshakeC2SPacket;
+import net.minecraft.server.network.ServerHandshakeNetworkHandler;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import ru.ruscalworld.fabricexporter.FabricExporter;
+import ru.ruscalworld.fabricexporter.MetricRegistry;
+
+@Mixin(ServerHandshakeNetworkHandler.class)
+public class ServerHandshakeNetworkHandlerMixin {
+    @Inject(method = "onHandshake", at = @At("HEAD"))
+    public void onHandshake(HandshakeC2SPacket packet, CallbackInfo info) {
+        MetricRegistry metricRegistry = FabricExporter.getInstance().getMetricRegistry();
+        Collector collector = metricRegistry.getCustomMetrics().get("handshakes");
+        if (!(collector instanceof Counter)) return;
+        Counter counter = (Counter) collector;
+        counter.labels(packet.getIntendedState().name().toLowerCase()).inc();
+    }
+}

src/main/resources/fabricexporter.mixins.json

@@ -3,9 +3,8 @@
   "minVersion": "0.8",
   "package": "ru.ruscalworld.fabricexporter.mixin",
   "compatibilityLevel": "JAVA_8",
-  "mixins": [
+  "server": [
-  ],
+    "ServerHandshakeNetworkHandlerMixin"
-  "client": [
   ],
   "injectors": {
     "defaultRequire": 1