diff --git a/build.gradle.kts b/build.gradle.kts
index 2a8af91ff..9637f7cd1 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -5,26 +5,22 @@ buildscript {
     repositories {
         mavenLocal()
         maven(url = "https://mirrors.huaweicloud.com/repository/maven")
+        maven(url = "https://dl.bintray.com/kotlin/kotlin-eap")
         jcenter()
-        // mavenCentral()
         google()
-        // maven (url="https://dl.bintray.com/kotlin/kotlin-eap")
     }
 
     dependencies {
-        val kotlinVersion: String by project
-        val atomicFuVersion: String by project
-
-        classpath("com.android.tools.build:gradle:3.5.3")
-        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion")
-        // classpath("com.github.jengelman.gradle.plugins:shadow:5.2.0")
-        classpath("org.jetbrains.kotlin:kotlin-serialization:$kotlinVersion")
-        classpath("org.jetbrains.kotlinx:atomicfu-gradle-plugin:$atomicFuVersion")
+        classpath("com.android.tools.build:gradle:${Versions.Android.androidGradlePlugin}")
+        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${Versions.Kotlin.stdlib}")
+        classpath("org.jetbrains.kotlin:kotlin-serialization:${Versions.Kotlin.stdlib}")
+        classpath("org.jetbrains.kotlinx:atomicfu-gradle-plugin:${Versions.Kotlin.atomicFU}")
     }
 }
 
 plugins {
-    id("org.jetbrains.dokka") version "0.10.1" apply false
+    id("org.jetbrains.dokka") version Versions.Kotlin.dokka apply false
+    id("com.jfrog.bintray") version Versions.Publishing.bintray apply false
 }
 
 runCatching {
@@ -43,11 +39,9 @@ allprojects {
     version = getProperty("miraiVersion")
 
     repositories {
-        mavenLocal()
         maven(url = "https://mirrors.huaweicloud.com/repository/maven")
+        maven(url = "https://dl.bintray.com/kotlin/kotlin-eap")
         jcenter()
-        // mavenCentral()
         google()
-        // maven (url="https://dl.bintray.com/kotlin/kotlin-eap")
     }
 }
\ No newline at end of file
diff --git a/buildSrc/build.gradle.kts b/buildSrc/build.gradle.kts
new file mode 100644
index 000000000..c39a297b0
--- /dev/null
+++ b/buildSrc/build.gradle.kts
@@ -0,0 +1,7 @@
+plugins {
+    `kotlin-dsl`
+}
+
+repositories {
+    jcenter()
+}
\ No newline at end of file
diff --git a/buildSrc/src/main/kotlin/dependencies.kt b/buildSrc/src/main/kotlin/dependencies.kt
new file mode 100644
index 000000000..113a734e4
--- /dev/null
+++ b/buildSrc/src/main/kotlin/dependencies.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2020 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
+ */
+
+object Versions {
+    object Mirai {
+        const val version = "0.30.0"
+    }
+
+    object Kotlin {
+        const val stdlib = "1.4-M1"
+        const val coroutines = "1.3.5-1.4-M1"
+        const val atomicFU = "0.14.2-1.4-M1"
+        const val serialization = "0.20.0-1.4-M1"
+        const val ktor = "1.3.2-1.4-M1"
+
+        const val io = "0.1.16"
+        const val coroutinesIo = "0.1.16"
+        const val dokka = "0.10.1"
+    }
+
+    object Android {
+        const val androidGradlePlugin = "3.5.3"
+    }
+
+    object Publishing {
+        const val bintray = "1.8.4-jetbrains-3"
+
+    }
+
+}
+
+@Suppress("unused")
+fun kotlinx(id: String, version: String) = "org.jetbrains.kotlinx:kotlinx-$id:$version"
+
+@Suppress("unused")
+fun ktor(id: String, version: String) = "io.ktor:ktor-$id:$version"
diff --git a/compatibility-validator/build.gradle.kts b/compatibility-validator/build.gradle.kts
index 0d4856c6e..0cfb04292 100644
--- a/compatibility-validator/build.gradle.kts
+++ b/compatibility-validator/build.gradle.kts
@@ -7,11 +7,6 @@ plugins {
 
 description = "Binary and source compatibility validator for mirai-core and mirai-core-qqandroid"
 
-val kotlinVersion: String by rootProject.ext
-val coroutinesVersion: String by rootProject.ext
-
-fun kotlinx(id: String, version: String) = "org.jetbrains.kotlinx:kotlinx-$id:$version"
-
 kotlin {
     sourceSets {
         all {
@@ -23,7 +18,7 @@ kotlin {
             dependencies {
                 api(kotlin("stdlib"))
                 api(project(":mirai-core-qqandroid"))
-                api(kotlinx("coroutines-core", coroutinesVersion))
+                api(kotlinx("coroutines-core", Versions.Kotlin.coroutines))
             }
         }
     }
diff --git a/gradle.properties b/gradle.properties
index 6b7afb12f..f6a30e62f 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,16 +1,5 @@
 # style guide
 kotlin.code.style=official
 # config
-miraiVersion=0.29.1
 kotlin.incremental.multiplatform=true
-kotlin.parallel.tasks.in.project=true
-# kotlin
-kotlinVersion=1.3.70
-# kotlin libraries
-serializationVersion=0.20.0
-coroutinesVersion=1.3.4
-atomicFuVersion=0.14.1
-kotlinXIoVersion=0.1.16
-coroutinesIoVersion=0.1.16
-# utility
-ktorVersion=1.3.2
\ No newline at end of file
+kotlin.parallel.tasks.in.project=true
\ No newline at end of file
diff --git a/mirai-core-qqandroid/build.gradle.kts b/mirai-core-qqandroid/build.gradle.kts
index 44d951490..55e009d54 100644
--- a/mirai-core-qqandroid/build.gradle.kts
+++ b/mirai-core-qqandroid/build.gradle.kts
@@ -3,34 +3,15 @@
 plugins {
     kotlin("multiplatform")
     id("kotlinx-atomicfu")
-    id("kotlinx-serialization")
+    kotlin("plugin.serialization")
     `maven-publish`
-    id("com.jfrog.bintray") version "1.8.4-jetbrains-3"
+    id("com.jfrog.bintray")
 }
 
-val kotlinVersion: String by rootProject.ext
-val atomicFuVersion: String by rootProject.ext
-val coroutinesVersion: String by rootProject.ext
-val kotlinXIoVersion: String by rootProject.ext
-val coroutinesIoVersion: String by rootProject.ext
-
-
-val ktorVersion: String by rootProject.ext
-
-val serializationVersion: String by rootProject.ext
-
-fun kotlinx(id: String, version: String) = "org.jetbrains.kotlinx:kotlinx-$id:$version"
-
-fun ktor(id: String, version: String) = "io.ktor:ktor-$id:$version"
-
-
 description = "QQ protocol library"
 
 val isAndroidSDKAvailable: Boolean by project
 
-val miraiVersion: String by project
-version = miraiVersion
-
 kotlin {
     if (isAndroidSDKAvailable) {
         apply(from = rootProject.file("gradle/android.gradle"))
@@ -58,30 +39,29 @@ kotlin {
     sourceSets {
         all {
             languageSettings.enableLanguageFeature("InlineClasses")
-
             languageSettings.useExperimentalAnnotation("kotlin.Experimental")
 
             dependencies {
                 api(project(":mirai-core"))
-
-                api(kotlin("stdlib", kotlinVersion))
-
-                api("org.jetbrains.kotlinx:atomicfu:$atomicFuVersion")
-                api(kotlinx("io", kotlinXIoVersion))
-                api(kotlinx("coroutines-io", coroutinesIoVersion))
-                api(kotlinx("coroutines-core", coroutinesVersion))
             }
         }
+
         commonMain {
             dependencies {
-                api(kotlinx("serialization-runtime-common", serializationVersion))
-                api(kotlinx("serialization-protobuf-common", serializationVersion))
+                api(kotlin("stdlib", Versions.Kotlin.stdlib))
+                api(kotlinx("serialization-runtime-common", Versions.Kotlin.serialization))
+                api(kotlinx("serialization-protobuf-common", Versions.Kotlin.serialization))
+                api("org.jetbrains.kotlinx:atomicfu:${Versions.Kotlin.atomicFU}")
+                api(kotlinx("io", Versions.Kotlin.io))
+                api(kotlinx("coroutines-io", Versions.Kotlin.coroutinesIo))
+                api(kotlinx("coroutines-core", Versions.Kotlin.coroutines))
             }
         }
+
         commonTest {
             dependencies {
-                api(kotlin("test-annotations-common"))
-                api(kotlin("test-common"))
+                implementation(kotlin("test-annotations-common"))
+                implementation(kotlin("test-common"))
                 implementation(kotlin("script-runtime"))
             }
         }
@@ -89,14 +69,14 @@ kotlin {
         if (isAndroidSDKAvailable) {
             val androidMain by getting {
                 dependencies {
-                    api(kotlinx("serialization-protobuf", serializationVersion))
+                    api(kotlinx("serialization-protobuf", Versions.Kotlin.serialization))
                 }
             }
 
             val androidTest by getting {
                 dependencies {
-                    implementation(kotlin("test", kotlinVersion))
-                    implementation(kotlin("test-junit", kotlinVersion))
+                    implementation(kotlin("test", Versions.Kotlin.stdlib))
+                    implementation(kotlin("test-junit", Versions.Kotlin.stdlib))
                     implementation(kotlin("test-annotations-common"))
                     implementation(kotlin("test-common"))
                 }
@@ -106,16 +86,16 @@ kotlin {
         val jvmMain by getting {
             dependencies {
                 runtimeOnly(files("build/classes/kotlin/jvm/main")) // classpath is not properly set by IDE
-                api(kotlinx("serialization-runtime", serializationVersion))
-                //api(kotlinx("serialization-protobuf", serializationVersion))
+                api(kotlinx("serialization-runtime", Versions.Kotlin.serialization))
+                //api(kotlinx("serialization-protobuf", Versions.Kotlin.serialization))
 
             }
         }
 
         val jvmTest by getting {
             dependencies {
-                api(kotlin("test", kotlinVersion))
-                api(kotlin("test-junit", kotlinVersion))
+                implementation(kotlin("test", Versions.Kotlin.stdlib))
+                implementation(kotlin("test-junit", Versions.Kotlin.stdlib))
                 implementation("org.pcap4j:pcap4j-distribution:1.8.2")
 
                 runtimeOnly(files("build/classes/kotlin/jvm/main")) // classpath is not properly set by IDE
@@ -124,9 +104,5 @@ kotlin {
         }
     }
 }
-//
-//tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
-//    kotlinOptions.jvmTarget = "1.8"
-//}
 
 apply(from = rootProject.file("gradle/publish.gradle"))
diff --git a/mirai-core/build.gradle.kts b/mirai-core/build.gradle.kts
index 40cc278ac..f69c91999 100644
--- a/mirai-core/build.gradle.kts
+++ b/mirai-core/build.gradle.kts
@@ -3,35 +3,16 @@
 plugins {
     kotlin("multiplatform")
     id("kotlinx-atomicfu")
-    id("kotlinx-serialization")
+    kotlin("plugin.serialization")
     id("org.jetbrains.dokka")
     `maven-publish`
-    id("com.jfrog.bintray") version "1.8.4-jetbrains-3"
+    id("com.jfrog.bintray")
 }
 
-val kotlinVersion: String by rootProject.ext
-val atomicFuVersion: String by rootProject.ext
-val coroutinesVersion: String by rootProject.ext
-val kotlinXIoVersion: String by rootProject.ext
-val coroutinesIoVersion: String by rootProject.ext
-
-
-val ktorVersion: String by rootProject.ext
-
-val serializationVersion: String by rootProject.ext
-
-fun kotlinx(id: String, version: String) = "org.jetbrains.kotlinx:kotlinx-$id:$version"
-
-fun ktor(id: String, version: String) = "io.ktor:ktor-$id:$version"
-
-
 description = "QQ protocol library"
 
 val isAndroidSDKAvailable: Boolean by project
 
-val miraiVersion: String by project
-version = miraiVersion
-
 kotlin {
     if (isAndroidSDKAvailable) {
         apply(from = rootProject.file("gradle/android.gradle"))
@@ -63,22 +44,22 @@ kotlin {
 
         commonMain {
             dependencies {
-                api(kotlin("stdlib", kotlinVersion))
-                api(kotlin("serialization", kotlinVersion))
-                api(kotlin("reflect", kotlinVersion))
+                api(kotlin("stdlib"))
+                api(kotlin("serialization"))
+                api(kotlin("reflect"))
 
-                api(kotlinx("coroutines-core-common", coroutinesVersion))
-                api(kotlinx("serialization-runtime-common", serializationVersion))
-                api(kotlinx("serialization-protobuf-common", serializationVersion))
-                api(kotlinx("io", kotlinXIoVersion))
-                api(kotlinx("coroutines-io", coroutinesIoVersion))
-                api(kotlinx("coroutines-core", coroutinesVersion))
+                api(kotlinx("coroutines-core-common", Versions.Kotlin.coroutines))
+                api(kotlinx("serialization-runtime-common", Versions.Kotlin.serialization))
+                api(kotlinx("serialization-protobuf-common", Versions.Kotlin.serialization))
+                api(kotlinx("io", Versions.Kotlin.io))
+                api(kotlinx("coroutines-io", Versions.Kotlin.coroutinesIo))
+                api(kotlinx("coroutines-core", Versions.Kotlin.coroutines))
 
-                api("org.jetbrains.kotlinx:atomicfu-common:$atomicFuVersion")
+                api("org.jetbrains.kotlinx:atomicfu-common:${Versions.Kotlin.atomicFU}")
 
-                api(ktor("client-cio", ktorVersion))
-                api(ktor("client-core", ktorVersion))
-                api(ktor("network", ktorVersion))
+                api(ktor("client-cio", Versions.Kotlin.ktor))
+                api(ktor("client-core", Versions.Kotlin.ktor))
+                api(ktor("network", Versions.Kotlin.ktor))
             }
         }
         commonTest {
@@ -91,22 +72,22 @@ kotlin {
         if (isAndroidSDKAvailable) {
             val androidMain by getting {
                 dependencies {
-                    api(kotlin("reflect", kotlinVersion))
+                    api(kotlin("reflect"))
 
-                    api(kotlinx("io-jvm", kotlinXIoVersion))
-                    api(kotlinx("serialization-runtime", serializationVersion))
-                    api(kotlinx("serialization-protobuf", serializationVersion))
-                    api(kotlinx("coroutines-android", coroutinesVersion))
-                    api(kotlinx("coroutines-io-jvm", coroutinesIoVersion))
+                    api(kotlinx("io-jvm", Versions.Kotlin.io))
+                    api(kotlinx("serialization-runtime", Versions.Kotlin.serialization))
+                    api(kotlinx("serialization-protobuf", Versions.Kotlin.serialization))
+                    api(kotlinx("coroutines-android", Versions.Kotlin.coroutines))
+                    api(kotlinx("coroutines-io-jvm", Versions.Kotlin.coroutinesIo))
 
-                    api(ktor("client-android", ktorVersion))
+                    api(ktor("client-android", Versions.Kotlin.ktor))
                 }
             }
 
             val androidTest by getting {
                 dependencies {
-                    implementation(kotlin("test", kotlinVersion))
-                    implementation(kotlin("test-junit", kotlinVersion))
+                    implementation(kotlin("test"))
+                    implementation(kotlin("test-junit"))
                     implementation(kotlin("test-annotations-common"))
                     implementation(kotlin("test-common"))
                 }
@@ -115,16 +96,16 @@ kotlin {
 
         val jvmMain by getting {
             dependencies {
-                //api(kotlin("stdlib-jdk8", kotlinVersion))
-                //api(kotlin("stdlib-jdk7", kotlinVersion))
-                api(kotlin("reflect", kotlinVersion))
+                //api(kotlin("stdlib-jdk8"))
+                //api(kotlin("stdlib-jdk7"))
+                api(kotlin("reflect"))
 
-                api(ktor("client-core-jvm", ktorVersion))
-                api(kotlinx("io-jvm", kotlinXIoVersion))
-                api(kotlinx("serialization-runtime", serializationVersion))
-                api(kotlinx("serialization-protobuf", serializationVersion))
-                api(kotlinx("coroutines-io-jvm", coroutinesIoVersion))
-                api(kotlinx("coroutines-core", coroutinesVersion))
+                api(ktor("client-core-jvm", Versions.Kotlin.ktor))
+                api(kotlinx("io-jvm", Versions.Kotlin.io))
+                api(kotlinx("serialization-runtime", Versions.Kotlin.serialization))
+                api(kotlinx("serialization-protobuf", Versions.Kotlin.serialization))
+                api(kotlinx("coroutines-io-jvm", Versions.Kotlin.coroutinesIo))
+                api(kotlinx("coroutines-core", Versions.Kotlin.coroutines))
 
                 api("org.bouncycastle:bcprov-jdk15on:1.64")
                 runtimeOnly(files("build/classes/kotlin/jvm/main")) // classpath is not properly set by IDE
@@ -133,8 +114,8 @@ kotlin {
 
         val jvmTest by getting {
             dependencies {
-                implementation(kotlin("test", kotlinVersion))
-                implementation(kotlin("test-junit", kotlinVersion))
+                implementation(kotlin("test"))
+                implementation(kotlin("test-junit"))
                 implementation("org.pcap4j:pcap4j-distribution:1.8.2")
 
                 runtimeOnly(files("build/classes/kotlin/jvm/test")) // classpath is not properly set by IDE
@@ -142,10 +123,7 @@ kotlin {
         }
     }
 }
-//
-//tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
-//    kotlinOptions.jvmTarget = "1.8"
-//}
+
 tasks {
     val dokka by getting(org.jetbrains.dokka.gradle.DokkaTask::class) {
         outputFormat = "html"
diff --git a/mirai-core/src/androidMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt b/mirai-core/src/androidMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
index 1b3fb785f..2edd1ae6b 100644
--- a/mirai-core/src/androidMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
+++ b/mirai-core/src/androidMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
@@ -1,6 +1,10 @@
 package net.mamoe.mirai.event.internal
 
+import net.mamoe.mirai.event.Event
+import net.mamoe.mirai.event.Listener
+import net.mamoe.mirai.utils.LockFreeLinkedList
 import java.util.concurrent.atomic.AtomicBoolean
+import kotlin.reflect.KClass
 
 internal actual class MiraiAtomicBoolean actual constructor(initial: Boolean) {
     private val delegate: AtomicBoolean = AtomicBoolean(initial)
@@ -14,4 +18,25 @@ internal actual class MiraiAtomicBoolean actual constructor(initial: Boolean) {
         set(value) {
             delegate.set(value)
         }
+}
+
+internal actual class EventListeners<E : Event> actual constructor(clazz: KClass<E>) :
+    LockFreeLinkedList<Listener<E>>() {
+    @Suppress("UNCHECKED_CAST", "UNSUPPORTED", "NO_REFLECTION_IN_CLASS_PATH")
+    actual val supertypes: Set<KClass<out Event>> by lazy {
+        val supertypes = mutableSetOf<KClass<out Event>>()
+
+        fun addSupertypes(clazz: KClass<out Event>) {
+            clazz.supertypes.forEach {
+                val classifier = it.classifier as? KClass<out Event>
+                if (classifier != null) {
+                    supertypes.add(classifier)
+                    addSupertypes(classifier)
+                }
+            }
+        }
+        addSupertypes(clazz)
+
+        supertypes
+    }
 }
\ No newline at end of file
diff --git a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
index 0b468cf04..36a9236f5 100644
--- a/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
+++ b/mirai-core/src/jvmMain/kotlin/net/mamoe/mirai/event/internal/MiraiAtomicBoolean.kt
@@ -1,6 +1,10 @@
 package net.mamoe.mirai.event.internal
 
+import net.mamoe.mirai.event.Event
+import net.mamoe.mirai.event.Listener
+import net.mamoe.mirai.utils.LockFreeLinkedList
 import java.util.concurrent.atomic.AtomicBoolean
+import kotlin.reflect.KClass
 
 
 internal actual class MiraiAtomicBoolean actual constructor(initial: Boolean) {
@@ -15,4 +19,25 @@ internal actual class MiraiAtomicBoolean actual constructor(initial: Boolean) {
         set(value) {
             delegate.set(value)
         }
+}
+
+internal actual class EventListeners<E : Event> actual constructor(clazz: KClass<E>) :
+    LockFreeLinkedList<Listener<E>>() {
+    @Suppress("UNCHECKED_CAST", "UNSUPPORTED", "NO_REFLECTION_IN_CLASS_PATH")
+    actual val supertypes: Set<KClass<out Event>> by lazy {
+        val supertypes = mutableSetOf<KClass<out Event>>()
+
+        fun addSupertypes(clazz: KClass<out Event>) {
+            clazz.supertypes.forEach {
+                val classifier = it.classifier as? KClass<out Event>
+                if (classifier != null) {
+                    supertypes.add(classifier)
+                    addSupertypes(classifier)
+                }
+            }
+        }
+        addSupertypes(clazz)
+
+        supertypes
+    }
 }
\ No newline at end of file