feat(metrics): 初步增加获取运行指标的功能(兼容 Prometheus).

添加兼容 Prometheus 的运行指标收集导出功能, 通过内置 HttpServer 将其导出.
默认关闭.

scalabot-app/src/main/kotlin/ScalaBot.kt

@@ -1,5 +1,8 @@
 package net.lamgc.scalabot
 
+import io.prometheus.client.Counter
+import io.prometheus.client.Gauge
+import io.prometheus.client.Summary
 import mu.KotlinLogging
 import org.eclipse.aether.artifact.Artifact
 import org.telegram.abilitybots.api.bot.AbilityBot
@@ -7,6 +10,7 @@ import org.telegram.abilitybots.api.db.DBContext
 import org.telegram.abilitybots.api.toggle.BareboneToggle
 import org.telegram.abilitybots.api.toggle.DefaultToggle
 import org.telegram.telegrambots.bots.DefaultBotOptions
+import org.telegram.telegrambots.meta.api.objects.Update
 
 internal class ScalaBot(
     name: String,
@@ -22,6 +26,51 @@ internal class ScalaBot(
     companion object {
         @JvmStatic
         private val log = KotlinLogging.logger { }
+
+        // ------------- Metrics -------------
+
+        @JvmStatic
+        private val botUpdateCounter = Counter.build()
+            .name("updates_total")
+            .help("Total number of updates received by all bots.")
+            .labelNames("bot_name")
+            .subsystem("telegrambots")
+            .register()
+
+        @JvmStatic
+        private val botUpdateGauge = Gauge.build()
+            .name("updates_in_progress")
+            .help("Number of updates in process by all bots.")
+            .labelNames("bot_name")
+            .subsystem("telegrambots")
+            .register()
+
+        @JvmStatic
+        private val onlineBotGauge = Gauge.build()
+            .name("bots_online")
+            .help("Number of bots Online.")
+            .subsystem("telegrambots")
+            .register()
+
+        @JvmStatic
+        private val updateProcessTime = Summary.build()
+            .name("update_process_duration_seconds")
+            .help(
+                "Time to process update. (This indicator includes the pre-processing of update by TelegrammBots, " +
+                        "so it may be different from the actual execution time of ability. " +
+                        "It is not recommended to use it as the accurate execution time of ability)"
+            )
+            .labelNames("bot_name")
+            .subsystem("telegrambots")
+            .register()
+
+        @JvmStatic
+        private val exceptionHandlingCounter = Counter.build()
+            .name("updates_exception_handling")
+            .help("Number of exceptions during processing.")
+            .labelNames("bot_name")
+            .subsystem("telegrambots")
+            .register()
     }
 
     private val extensionLoader = ExtensionLoader(this)
@@ -38,4 +87,30 @@ internal class ScalaBot(
     }
 
     override fun creatorId(): Long = creatorId
+
+    override fun onUpdateReceived(update: Update?) {
+        botUpdateCounter.labels(botUsername).inc()
+        botUpdateGauge.labels(botUsername).inc()
+
+        val timer = updateProcessTime.labels(botUsername).startTimer()
+        try {
+            super.onUpdateReceived(update)
+        } catch (e: Exception) {
+            exceptionHandlingCounter.labels(botUsername).inc()
+            throw e
+        } finally {
+            timer.observeDuration()
+            botUpdateGauge.labels(botUsername).dec()
+        }
+    }
+
+    override fun onRegister() {
+        super.onRegister()
+        onlineBotGauge.inc()
+    }
+
+    override fun onClosing() {
+        super.onClosing()
+        onlineBotGauge.dec()
+    }
 }