Added ExternalBridgeSelectionStrategy and related config

src/main/kotlin/org/jitsi/jicofo/bridge/ExternalBridgeSelectionStrategy.kt

@@ -0,0 +1,110 @@
+package org.jitsi.jicofo.bridge
+
+import org.jitsi.utils.logging2.Logger
+import org.jitsi.utils.logging2.LoggerImpl
+import org.json.simple.JSONObject
+import org.json.simple.JSONValue
+import java.net.URI
+import java.net.http.HttpClient
+import java.net.http.HttpRequest
+import java.net.http.HttpResponse
+
+@Suppress("unused")
+class ExternalBridgeSelectionStrategy() : BridgeSelectionStrategy() {
+    private val httpClient: HttpClient = HttpClient
+        .newBuilder()
+        .connectTimeout(ExternalBridgeSelectionStrategyConfig.config.timeout)
+        .build()
+
+    private val logger: Logger = LoggerImpl(ExternalBridgeSelectionStrategy::class.simpleName)
+
+    private val fallbackStrategy: BridgeSelectionStrategy? by lazy {
+        val fallbackStrategyName = ExternalBridgeSelectionStrategyConfig.config.fallbackStrategy ?: return@lazy null
+        try {
+            val clazz = Class.forName("${javaClass.getPackage().name}.$fallbackStrategyName")
+            clazz.getConstructor().newInstance() as BridgeSelectionStrategy
+        } catch (e: Exception) {
+            val clazz = Class.forName(fallbackStrategyName)
+            clazz.getConstructor().newInstance() as BridgeSelectionStrategy
+        }
+    }
+
+    private fun fallback(
+        bridges: MutableList<Bridge>?,
+        conferenceBridges: MutableMap<Bridge, Int>?,
+        participantRegion: String?
+    ): Bridge {
+        if (fallbackStrategy == null) {
+            throw Exception("External bridge selection failed and no fallbackStrategy was provided.")
+        }
+        return fallbackStrategy!!.doSelect(bridges, conferenceBridges, participantRegion)
+    }
+
+    override fun doSelect(
+        bridges: MutableList<Bridge>?,
+        conferenceBridges: MutableMap<Bridge, Int>?,
+        participantRegion: String?
+    ): Bridge {
+        val url = ExternalBridgeSelectionStrategyConfig.config.url
+            ?: throw Exception("ExternalBridgeSelectionStrategy requires url to be provided")
+
+        val requestBody = JSONObject()
+        requestBody["bridges"] = bridges?.map {
+            mapOf(
+                "jid" to it.jid.toString(),
+                "version" to it.version,
+                "colibri2" to it.supportsColibri2(),
+                "relay_id" to it.relayId,
+                "region" to it.region,
+                "stress" to it.stress,
+                "operational" to it.isOperational,
+                "graceful_shutdown" to it.isInGracefulShutdown,
+                "draining" to it.isDraining,
+            )
+        }
+        requestBody["conference_bridges"] = conferenceBridges?.mapKeys { it.key.jid.toString() }
+        requestBody["participant_region"] = participantRegion
+        requestBody["fallback_strategy"] = ExternalBridgeSelectionStrategyConfig.config.fallbackStrategy
+
+        val request = HttpRequest
+            .newBuilder()
+            .POST(HttpRequest.BodyPublishers.ofString(requestBody.toJSONString()))
+            .uri(URI.create(url))
+            .headers("Content-Type", "application/json")
+            .timeout(ExternalBridgeSelectionStrategyConfig.config.timeout)
+            .build()
+
+        val response: HttpResponse<String>
+        try {
+            response = httpClient.send(request, HttpResponse.BodyHandlers.ofString())
+        } catch (exc: Exception) {
+            logger.error("ExternalBridgeSelectionStrategy: HTTP request failed with ${exc}, using fallback strategy")
+            return fallback(bridges, conferenceBridges, participantRegion)
+        }
+
+        val statusCode = response.statusCode()
+        if (statusCode !in 200..299) {
+            logger.error("ExternalBridgeSelectionStrategy: HTTP request failed with ${statusCode}, using fallback strategy")
+            return fallback(bridges, conferenceBridges, participantRegion)
+        }
+
+        val responseBody: JSONObject
+        try {
+            responseBody = JSONValue.parseWithException(response.body()) as JSONObject
+        } catch (exc: Exception) {
+            logger.error("ExternalBridgeSelectionStrategy: HTTP response parsing failed with ${exc}, using fallback strategy")
+            return fallback(bridges, conferenceBridges, participantRegion)
+        }
+
+        val selectedBridgeIndex = responseBody["selected_bridge_index"] as? Number
+
+        if (selectedBridgeIndex == null) {
+            logger.error("ExternalBridgeSelectionStrategy: HTTP response selected_bridge_index missing or invalid, using fallback strategy")
+            return fallback(bridges, conferenceBridges, participantRegion)
+        }
+
+        val bridge = bridges!![selectedBridgeIndex.toInt()]
+        logger.info("ExternalBridgeSelectionStrategy: participantRegion=${participantRegion}, bridge=${bridge}")
+        return bridge
+    }
+}

src/main/kotlin/org/jitsi/jicofo/bridge/ExternalBridgeSelectionStrategyConfig.kt

@@ -0,0 +1,29 @@
+package org.jitsi.jicofo.bridge
+
+import org.jitsi.config.JitsiConfig
+import org.jitsi.metaconfig.optionalconfig
+import java.time.Duration
+
+class ExternalBridgeSelectionStrategyConfig private constructor() {
+    val url: String? by optionalconfig {
+        "${BASE}.url".from(JitsiConfig.newConfig)
+    }
+    fun url() = url
+
+    val timeout: Duration? by optionalconfig {
+        "${BASE}.timeout".from(JitsiConfig.newConfig)
+    }
+    fun timeout() = timeout
+
+    val fallbackStrategy: String? by optionalconfig {
+        "${BASE}.fallback-strategy".from(JitsiConfig.newConfig)
+    }
+    fun fallbackStrategy() = fallbackStrategy
+
+    companion object {
+        const val BASE = "jicofo.bridge.external-selection-strategy"
+
+        @JvmField
+        val config = ExternalBridgeSelectionStrategyConfig()
+    }
+}