Test: NettyEndlessReconnectionTest

mirai-core-utils/src/commonMain/kotlin/StandardUtils.kt

@@ -169,6 +169,10 @@ public fun systemProp(name: String, default: Boolean): Boolean =
     System.getProperty(name, default.toString())?.toBoolean() ?: default
 
 
+public fun systemProp(name: String, default: Long): Long =
+    System.getProperty(name, default.toString())?.toLongOrNull() ?: default
+
+
 public fun Throwable.getRootCause(maxDepth: Int = 20): Throwable {
     var depth = 0
     var rootCause: Throwable? = this

mirai-core/src/commonMain/kotlin/network/impl/netty/NettyNetworkHandler.kt

@@ -32,6 +32,7 @@ import net.mamoe.mirai.internal.network.protocol.packet.OutgoingPacket
 import net.mamoe.mirai.utils.ExceptionCollector
 import net.mamoe.mirai.utils.childScope
 import net.mamoe.mirai.utils.debug
+import net.mamoe.mirai.utils.systemProp
 import java.net.SocketAddress
 import kotlin.coroutines.CoroutineContext
 import io.netty.channel.Channel as NettyChannel
@@ -206,9 +207,7 @@ internal open class NettyNetworkHandler(
         wait: Boolean = false
     ) : NettyState(State.CONNECTING) {
         private val connection = async {
-            if (wait) {
-                delay(5000)
-            }
+            if (wait) delay(RECONNECT_DELAY)
             createConnection(decodePipeline)
         }
 
@@ -346,4 +345,12 @@ internal open class NettyNetworkHandler(
     }
 
     override fun initialState(): BaseStateImpl = StateInitialized()
+
+    companion object {
+        /**
+         * millis
+         */
+        @JvmField
+        var RECONNECT_DELAY = systemProp("mirai.network.reconnect.delay", 5000)
+    }
 }

mirai-core/src/commonTest/kotlin/network/impl/netty/NettyEndlessReconnectionTest.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2019-2021 Mamoe Technologies and contributors.
+ *
+ *  此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ *  Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ *
+ *  https://github.com/mamoe/mirai/blob/master/LICENSE
+ */
+
+package net.mamoe.mirai.internal.network.impl.netty
+
+import io.netty.channel.Channel
+import kotlinx.coroutines.delay
+import net.mamoe.mirai.internal.network.handler.NetworkHandlerContext
+import net.mamoe.mirai.internal.network.handler.NetworkHandlerFactory
+import net.mamoe.mirai.internal.network.handler.NetworkHandlerSupport
+import net.mamoe.mirai.internal.test.runBlockingUnit
+import java.net.SocketAddress
+import kotlin.reflect.jvm.javaGetter
+import kotlin.test.Test
+import kotlin.test.assertTrue
+
+/**
+ * When offline, handler will try endlessly to re-establish a connection. Exceptions are preserved as suppressed exceptions however, duplicates must be dropped to save memory.
+ */
+internal class NettyEndlessReconnectionTest : AbstractNettyNHTest() {
+
+    override val factory: NetworkHandlerFactory<TestNettyNH> = object : NetworkHandlerFactory<TestNettyNH> {
+        override fun create(context: NetworkHandlerContext, address: SocketAddress): TestNettyNH {
+            return object : TestNettyNH(context, address) {
+                override suspend fun createConnection(decodePipeline: PacketDecodePipeline): Channel =
+                    error("fail")
+            }
+        }
+    }
+
+    @Test
+    fun `massive reconnection`() = runBlockingUnit {
+        val r = NettyNetworkHandler.Companion.RECONNECT_DELAY
+        NettyNetworkHandler.Companion.RECONNECT_DELAY = 0
+        network.setStateConnecting() // will connect endlessly and create a massive amount of exceptions
+        delay(10000) // if exceptions are ignored by ExceptionCollector, memory usage will not exceed limitation.
+
+        @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+        val state = network::_state.javaGetter!!.apply { isAccessible = true }
+            .invoke(network) as NetworkHandlerSupport.BaseStateImpl
+
+        assertTrue { state.getCause()!!.suppressed.size <= 1 } // might be zero if just created since at this time network is still running.
+        // size <= 1 means duplicates are dropped.
+
+
+        network.close(null)
+        NettyNetworkHandler.Companion.RECONNECT_DELAY = r
+    }
+}