Random and Round-Robin strategies can exclude dead outbounds (#5926)

* Add policy group fallback health checks

* Refine policy group observatory defaults

* Simplify policy group fallback

* Localize policy group fallback settings

* Update CoreConfigContextBuilder.kt

* Update CoreConfigManager.kt

* Restore implicit policy group fallback

---------

Co-authored-by: 2dust <31833384+2dust@users.noreply.github.com>

V2rayNG/app/src/main/java/com/v2ray/ang/core/CoreConfigContextBuilder.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import com.v2ray.ang.AppConfig
 import com.v2ray.ang.dto.CoreConfigContext
 import com.v2ray.ang.dto.entities.ProfileItem
+import com.v2ray.ang.enums.BalancerStrategyType
 import com.v2ray.ang.enums.CoreResolvedType
 import com.v2ray.ang.enums.EConfigType
 import com.v2ray.ang.extension.isComplexType
@@ -43,12 +44,14 @@ object CoreConfigContextBuilder {
 
         // Step 2: Resolve all non-builtin routing outbound tags.
         val routingResolvedOutbounds = resolveRoutingOutbounds()
+        val resolvedOutbounds = listOf(primaryResolvedOutbound) + routingResolvedOutbounds
+        val fallbackResolvedOutbounds = resolveFallbackOutbounds(resolvedOutbounds)
         val routingDomainRules = collectRoutingDomainRulesForDns()
 
         return CoreConfigContext(
             context = context,
             guid = guid,
-            resolvedOutbounds = listOf(primaryResolvedOutbound) + routingResolvedOutbounds,
+            resolvedOutbounds = resolvedOutbounds + fallbackResolvedOutbounds,
             routingDomainRules = routingDomainRules,
         )
     }
@@ -246,4 +249,25 @@ object CoreConfigContextBuilder {
 
         return result
     }
+
+    /**
+     * Resolve and collect fallback outbounds from all POLICYGROUP nodes.
+     *
+     * Fallback targets must not overlap with already resolved tags or builtin tags.
+     */
+    private fun resolveFallbackOutbounds(resolvedOutbounds: List<CoreConfigContext.ResolvedOutbound>): List<CoreConfigContext.ResolvedOutbound> {
+        return resolvedOutbounds
+            .asSequence()
+            .filter { it.resolvedType == CoreResolvedType.POLICYGROUP }
+            .filter { BalancerStrategyType.from(it.profile.policyGroupType).supportsObservatory && it.profile.policyGroupTestOutbounds != false }
+            .mapNotNull { it.profile.policyGroupFallbackTag }
+            .filter { it !in AppConfig.BUILTIN_OUTBOUND_TAGS && resolvedOutbounds.none { outbound -> outbound.tag == it } }
+            .distinct()
+            .mapNotNull { tag ->
+                SettingsManager.getServerViaRemarks(tag)
+                    ?.takeUnless { it.configType == EConfigType.CUSTOM || it.configType == EConfigType.POLICYGROUP }
+                    ?.let { resolveOutbound(tag, it) }
+            }
+            .toList()
+    }
 }

V2rayNG/app/src/main/java/com/v2ray/ang/core/CoreConfigManager.kt

@@ -374,10 +374,19 @@ object CoreConfigManager {
         } else {
             "${AppConfig.TAG_BALANCER_PRE}-${resolvedOutbound.tag}"
         }
+        val strategyType = BalancerStrategyType.from(resolvedOutbound.profile.policyGroupType)
+        val fallbackTag = if (strategyType.supportsObservatory && resolvedOutbound.profile.policyGroupTestOutbounds != false) {
+            resolvedOutbound.profile.policyGroupFallbackTag
+                ?.takeIf { it.isNotEmpty() && it != AppConfig.TAG_PROXY }
+                // Xray excludes dead random/roundRobin candidates only when fallbackTag is set;
+                // without this default, an enabled empty field creates no observatory.
+                ?: membersToAdd.first().tag
+        } else null
         val strategy = buildBalancerStrategy(
-            policyGroupType = resolvedOutbound.profile.policyGroupType,
+            strategyType = strategyType,
             selector = listOf(memberTagPrefix),
             balancerTag = balancerTag,
+            fallbackTag = fallbackTag,
         )
         val existingBalancers = v2rayConfig.routing.balancers?.toMutableList() ?: mutableListOf()
         if (existingBalancers.none { it.tag == balancerTag }) {
@@ -1180,9 +1189,10 @@ object CoreConfigManager {
      * Build balancer and probe settings from one policy-group strategy value.
      */
     private fun buildBalancerStrategy(
-        policyGroupType: String?,
+        strategyType: BalancerStrategyType,
         selector: List<String>,
         balancerTag: String = AppConfig.TAG_BALANCER,
+        fallbackTag: String? = null,
     ): BalancerStrategy {
         val probeUrl = MmkvManager.decodeSettingsString(AppConfig.PREF_DELAY_TEST_URL) ?: AppConfig.DELAY_TEST_URL
         val leastPingInterval = decodeObservatoryDuration(AppConfig.PREF_OBSERVATORY_LEAST_PING_INTERVAL, AppConfig.OBSERVATORY_LEAST_PING_INTERVAL)
@@ -1190,13 +1200,13 @@ object CoreConfigManager {
         val leastLoadMethod = MmkvManager.decodeSettingsString(AppConfig.PREF_OBSERVATORY_LEAST_LOAD_METHOD, AppConfig.OBSERVATORY_LEAST_LOAD_METHOD)
         val leastLoadSampling = decodeObservatorySampling()
         val leastLoadTimeout = decodeObservatoryDuration(AppConfig.PREF_OBSERVATORY_LEAST_LOAD_TIMEOUT, AppConfig.OBSERVATORY_LEAST_LOAD_TIMEOUT)
-        val strategyType = BalancerStrategyType.from(policyGroupType)
         val balancer = V2rayConfig.RoutingBean.BalancerBean(
             tag = balancerTag,
             selector = selector,
+            fallbackTag = fallbackTag,
             strategy = V2rayConfig.RoutingBean.StrategyObject(type = strategyType.policyGroupType)
         )
-        val observatory = if (strategyType.requiresObservatory) {
+        val observatory = if (strategyType.requiresObservatory || fallbackTag != null) {
             V2rayConfig.ObservatoryObject(
                 subjectSelector = selector,
                 probeUrl = probeUrl,

V2rayNG/app/src/main/java/com/v2ray/ang/dto/entities/ProfileItem.kt

@@ -67,6 +67,8 @@ data class ProfileItem(
     var policyGroupType: String? = null,
     var policyGroupSubscriptionId: String? = null,
     var policyGroupFilter: String? = null,
+    var policyGroupTestOutbounds: Boolean? = null,
+    var policyGroupFallbackTag: String? = null,
     var proxyChainProfiles: String? = null,
 
     var browserDialerMode: String? = null,

V2rayNG/app/src/main/java/com/v2ray/ang/enums/BalancerStrategyType.kt

@@ -7,20 +7,22 @@ package com.v2ray.ang.enums
  * @param policyGroupTypeValue The numeric string stored in [com.v2ray.ang.dto.entities.ProfileItem.policyGroupType].
  * @param requiresBurstObservatory Whether this strategy needs a burstObservatory (leastLoad).
  * @param requiresObservatory Whether this strategy needs an observatory (leastPing).
+ * @param supportsObservatory Whether an observatory can health-filter this strategy.
  */
 enum class BalancerStrategyType(
     val policyGroupType: String,
     val policyGroupTypeValue: String,
     val requiresBurstObservatory: Boolean = false,
     val requiresObservatory: Boolean = false,
+    val supportsObservatory: Boolean = false,
 ) {
     LEAST_LOAD("leastLoad", "1", requiresBurstObservatory = true),
-    RANDOM("random", "2"),
+    RANDOM("random", "2", supportsObservatory = true),
-    ROUND_ROBIN("roundRobin", "3"),
+    ROUND_ROBIN("roundRobin", "3", supportsObservatory = true),
     LEAST_PING("leastPing", "", requiresObservatory = true); // default / else
 
     companion object {
         fun from(policyGroupType: String?): BalancerStrategyType =
             entries.firstOrNull { it.policyGroupTypeValue == policyGroupType } ?: LEAST_PING
     }
-}
+}

V2rayNG/app/src/main/java/com/v2ray/ang/ui/server/ServerGroupActivity.kt

@@ -6,6 +6,8 @@ import androidx.compose.foundation.layout.consumeWindowInsets
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.Scaffold
@@ -21,17 +23,22 @@ import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringArrayResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
+import com.v2ray.ang.AppConfig.BUILTIN_OUTBOUND_TAGS
+import com.v2ray.ang.AppConfig.TAG_PROXY
 import com.v2ray.ang.R
 import com.v2ray.ang.compose.AppTopBar
 import com.v2ray.ang.compose.ConfirmDialog
 import com.v2ray.ang.compose.FormDropdownField
 import com.v2ray.ang.compose.FormTextField
+import com.v2ray.ang.compose.SettingsSwitchItem
 import com.v2ray.ang.dto.entities.ProfileItem
+import com.v2ray.ang.enums.BalancerStrategyType
 import com.v2ray.ang.enums.EConfigType
 import com.v2ray.ang.extension.isNotNullEmpty
 import com.v2ray.ang.extension.toast
 import com.v2ray.ang.extension.toastSuccess
 import com.v2ray.ang.handler.MmkvManager
+import com.v2ray.ang.handler.SettingsManager
 import com.v2ray.ang.ui.base.BaseComponentActivity
 
 class ServerGroupActivity : BaseComponentActivity() {
@@ -45,21 +52,32 @@ class ServerGroupActivity : BaseComponentActivity() {
     private val subscriptionId by lazy { intent.getStringExtra("subscriptionId") }
     private val subIds = mutableListOf<String>()
     private val subDisplay = mutableListOf<String>()
+    private lateinit var fallbackSuggestions: List<String>
 
     private lateinit var initialRemarks: String
     private lateinit var initialFilter: String
     private var initialType: Int = 0
     private var initialSubIndex: Int = 0
+    private var initialTestOutbounds: Boolean = false
+    private lateinit var initialFallbackTag: String
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         val config = MmkvManager.decodeServerConfig(editGuid)
         populateSubscriptionSpinner()
+        fallbackSuggestions = (
+            BUILTIN_OUTBOUND_TAGS + SettingsManager.getProfileRemarks(
+                excludeConfigTypes = setOf(EConfigType.CUSTOM, EConfigType.POLICYGROUP)
+            )
+        ).filter { it != TAG_PROXY }
 
         initialRemarks = config?.remarks ?: ""
         initialFilter = config?.policyGroupFilter ?: ""
         initialType = config?.policyGroupType?.toIntOrNull() ?: 0
+        initialTestOutbounds = config == null || config.policyGroupTestOutbounds != false ||
+                !BalancerStrategyType.from(config.policyGroupType).supportsObservatory
+        initialFallbackTag = config?.policyGroupFallbackTag.orEmpty()
         initialSubIndex = if (config != null) {
             subIds.indexOf(config.policyGroupSubscriptionId ?: "").let { if (it >= 0) it else 0 }
         } else if (subscriptionId.isNotNullEmpty()) {
@@ -77,8 +95,13 @@ class ServerGroupActivity : BaseComponentActivity() {
             initialFilter = initialFilter,
             initialType = initialType,
             initialSubIndex = initialSubIndex,
+            initialTestOutbounds = initialTestOutbounds,
+            initialFallbackTag = initialFallbackTag,
+            fallbackSuggestions = fallbackSuggestions,
             onBackClick = { finish() },
-            onSave = { remarks, filter, typeIdx, subIdx -> saveServer(remarks, filter, typeIdx, subIdx) },
+            onSave = { remarks, filter, typeIdx, subIdx, testOutbounds, fallbackTag ->
+                saveServer(remarks, filter, typeIdx, subIdx, testOutbounds, fallbackTag)
+            },
             onDelete = { deleteServer() }
         )
     }
@@ -87,7 +110,9 @@ class ServerGroupActivity : BaseComponentActivity() {
         remarks: String,
         filter: String,
         typeIdx: Int,
-        subIdx: Int
+        subIdx: Int,
+        testOutbounds: Boolean,
+        fallbackTag: String,
     ): Boolean {
         if (remarks.isBlank()) {
             toast(R.string.server_lab_remarks)
@@ -103,6 +128,8 @@ class ServerGroupActivity : BaseComponentActivity() {
         config.policyGroupType = typeIdx.toString()
         config.policyGroupSubscriptionId =
             subIds.getOrNull(subIdx)
+        config.policyGroupTestOutbounds = testOutbounds
+        config.policyGroupFallbackTag = fallbackTag.trim().takeIf { it.isNotEmpty() }
 
         if (
             config.subscriptionId.isEmpty() &&
@@ -189,8 +216,11 @@ fun ServerGroupScreen(
     initialFilter: String,
     initialType: Int,
     initialSubIndex: Int,
+    initialTestOutbounds: Boolean,
+    initialFallbackTag: String,
+    fallbackSuggestions: List<String>,
     onBackClick: () -> Unit,
-    onSave: (String, String, Int, Int) -> Boolean,
+    onSave: (String, String, Int, Int, Boolean, String) -> Boolean,
     onDelete: () -> Unit
 ) {
     val typeEntries = stringArrayResource(R.array.policy_group_type).toList()
@@ -199,8 +229,12 @@ fun ServerGroupScreen(
     var filter by rememberSaveable { mutableStateOf(initialFilter) }
     var typeValue by rememberSaveable { mutableStateOf(typeEntries.getOrNull(initialType).orEmpty()) }
     var subValue by rememberSaveable { mutableStateOf(subDisplay.getOrNull(initialSubIndex).orEmpty()) }
+    var testOutbounds by rememberSaveable { mutableStateOf(initialTestOutbounds) }
+    var fallbackTag by rememberSaveable { mutableStateOf(initialFallbackTag) }
     var showDeleteConfirm by remember { mutableStateOf(false) }
     val showDelete = editGuid.isNotEmpty() && !isRunning
+    val selectedType = typeEntries.indexOf(typeValue).coerceAtLeast(0).toString()
+    val supportsObservatory = BalancerStrategyType.from(selectedType).supportsObservatory
 
     Scaffold(
         contentWindowInsets = ScaffoldDefaults.contentWindowInsets,
@@ -217,7 +251,7 @@ fun ServerGroupScreen(
                     IconButton(onClick = {
                         val typeIdx = typeEntries.indexOf(typeValue).coerceAtLeast(0)
                         val subIdx = subDisplay.indexOf(subValue).coerceAtLeast(0)
-                        onSave(remarks, filter, typeIdx, subIdx)
+                        onSave(remarks, filter, typeIdx, subIdx, testOutbounds, fallbackTag)
                     }) {
                         Icon(painterResource(R.drawable.ic_fab_check), contentDescription = stringResource(R.string.menu_item_save_config))
                     }
@@ -232,6 +266,7 @@ fun ServerGroupScreen(
                 .consumeWindowInsets(innerPadding)
                 .imePadding()
                 .padding(vertical = 8.dp)
+                .verticalScroll(rememberScrollState())
         ) {
             FormTextField(stringResource(R.string.server_lab_remarks), remarks, { remarks = it })
             FormDropdownField(
@@ -247,6 +282,22 @@ fun ServerGroupScreen(
                 onValueChange = { subValue = it }
             )
             FormTextField(stringResource(R.string.title_policy_group_subscription_filter), filter, { filter = it })
+            if (supportsObservatory) {
+                SettingsSwitchItem(
+                    title = stringResource(R.string.title_policy_group_test_outbounds),
+                    checked = testOutbounds,
+                    onCheckedChange = { testOutbounds = it }
+                )
+                if (testOutbounds) {
+                    FormDropdownField(
+                        label = stringResource(R.string.title_policy_group_fallback),
+                        value = fallbackTag,
+                        options = fallbackSuggestions,
+                        onValueChange = { fallbackTag = it },
+                        editable = true
+                    )
+                }
+            }
         }
     }
 

V2rayNG/app/src/main/res/values-ar/strings.xml

@@ -387,6 +387,8 @@
     <string name="title_policy_group_type">Policy group type</string>
     <string name="title_policy_group_subscription_id">From subscription group</string>
     <string name="title_policy_group_subscription_filter">Remarks regular filter</string>
+    <string name="title_policy_group_test_outbounds">اختبار المخارج</string>
+    <string name="title_policy_group_fallback">المخرج الاحتياطي (اختياري)</string>
     <string name="server_proxy_chain_members">اعضاء سلسلة الوكيل</string>
     <string name="server_proxy_chain_pick_members">اضغط هنا لاختيار عضو</string>
     <string name="server_proxy_chain_member_unselected">اختر عضوا</string>

V2rayNG/app/src/main/res/values-bn/strings.xml

@@ -386,6 +386,8 @@
     <string name="title_policy_group_type">Policy group type</string>
     <string name="title_policy_group_subscription_id">From subscription group</string>
     <string name="title_policy_group_subscription_filter">Remarks regular filter</string>
+    <string name="title_policy_group_test_outbounds">আউটবাউন্ড পরীক্ষা করুন</string>
+    <string name="title_policy_group_fallback">ফলব্যাক আউটবাউন্ড (ঐচ্ছিক)</string>
     <string name="server_proxy_chain_members">Proxy chain members</string>
     <string name="server_proxy_chain_pick_members">Tap here to pick member</string>
     <string name="server_proxy_chain_member_unselected">Select a member</string>

V2rayNG/app/src/main/res/values-bqi-rIR/strings.xml

@@ -392,6 +392,8 @@
     <string name="title_policy_group_type">نوع بونکۊ سیاست</string>
     <string name="title_policy_group_subscription_id">ز بونکۊ اشتراک</string>
     <string name="title_policy_group_subscription_filter">توزیهات فیلتر معمۊلی</string>
+    <string name="title_policy_group_test_outbounds">آزمایش بارتا</string>
+    <string name="title_policy_group_fallback">بارت جایگزین (اختیاری)</string>
     <string name="server_proxy_chain_members">ٱئزا زنجیره پروکسی</string>
     <string name="server_proxy_chain_pick_members">سی پسند عوزو ایچو بزنین</string>
     <string name="server_proxy_chain_member_unselected">ی عوزو پسند کۊنین</string>

V2rayNG/app/src/main/res/values-fa/strings.xml

@@ -383,6 +383,8 @@
     <string name="title_policy_group_type">نوع گروه خط مشی</string>
     <string name="title_policy_group_subscription_id">از گروه اشتراک</string>
     <string name="title_policy_group_subscription_filter">توضیحات فیلتر معمولی</string>
+    <string name="title_policy_group_test_outbounds">آزمایش خروجی‌ها</string>
+    <string name="title_policy_group_fallback">خروجی جایگزین (اختیاری)</string>
     <string name="server_proxy_chain_members">اعضای زنجیره پروکسی</string>
     <string name="server_proxy_chain_pick_members">برای انتخاب عضو اینجا بزنید</string>
     <string name="server_proxy_chain_member_unselected">یک عضو را انتخاب کنید</string>

V2rayNG/app/src/main/res/values-ru/strings.xml

@@ -398,6 +398,8 @@
     <string name="title_policy_group_type">Тип политики группы</string>
     <string name="title_policy_group_subscription_id">Из группы подписки</string>
     <string name="title_policy_group_subscription_filter">Название фильтра</string>
+    <string name="title_policy_group_test_outbounds">Проверять исходящие соединения</string>
+    <string name="title_policy_group_fallback">Резервное исходящее соединение (необязательно)</string>
 
     <string name="server_proxy_chain_members">Участники цепочки прокси</string>
     <string name="server_proxy_chain_pick_members">Нажмите здесь, чтобы выбрать участника</string>

V2rayNG/app/src/main/res/values-vi/strings.xml

@@ -388,6 +388,8 @@
     <string name="title_policy_group_type">Policy group type</string>
     <string name="title_policy_group_subscription_id">From subscription group</string>
     <string name="title_policy_group_subscription_filter">Remarks regular filter</string>
+    <string name="title_policy_group_test_outbounds">Kiểm tra outbound</string>
+    <string name="title_policy_group_fallback">Outbound dự phòng (tùy chọn)</string>
     <string name="server_proxy_chain_members">Proxy chain members</string>
     <string name="server_proxy_chain_pick_members">Tap here to pick member</string>
     <string name="server_proxy_chain_member_unselected">Select a member</string>

V2rayNG/app/src/main/res/values-zh-rCN/strings.xml

@@ -402,6 +402,8 @@
     <string name="title_policy_group_type">策略组类型</string>
     <string name="title_policy_group_subscription_id">来自订阅分组</string>
     <string name="title_policy_group_subscription_filter">别名正则过滤</string>
+    <string name="title_policy_group_test_outbounds">测试出站</string>
+    <string name="title_policy_group_fallback">备用出站（可选）</string>
     <string name="server_proxy_chain_members">代理链成员</string>
     <string name="server_proxy_chain_pick_members">点此选择成员</string>
     <string name="server_proxy_chain_member_unselected">请选择成员</string>

V2rayNG/app/src/main/res/values-zh-rTW/strings.xml

@@ -400,6 +400,8 @@
     <string name="title_policy_group_type">策略群組類型</string>
     <string name="title_policy_group_subscription_id">來自訂閱分組</string>
     <string name="title_policy_group_subscription_filter">別名正規過濾</string>
+    <string name="title_policy_group_test_outbounds">測試出口</string>
+    <string name="title_policy_group_fallback">備用出口（選填）</string>
     <string name="server_proxy_chain_members">代理鏈成員</string>
     <string name="server_proxy_chain_pick_members">點此選擇成員</string>
     <string name="server_proxy_chain_member_unselected">請選擇成員</string>

V2rayNG/app/src/main/res/values/strings.xml

@@ -407,6 +407,8 @@
     <string name="title_policy_group_type">Policy group type</string>
     <string name="title_policy_group_subscription_id">From subscription group</string>
     <string name="title_policy_group_subscription_filter">Remarks regular filter</string>
+    <string name="title_policy_group_test_outbounds">Test outbounds</string>
+    <string name="title_policy_group_fallback">Fallback outbound (optional)</string>
 
     <string name="server_proxy_chain_members">Proxy chain members</string>
     <string name="server_proxy_chain_pick_members">Tap here to pick member</string>