diff --git a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/LockFreeLinkedList.kt b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/LockFreeLinkedList.kt
index bed669359..05683a812 100644
--- a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/LockFreeLinkedList.kt
+++ b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/LockFreeLinkedList.kt
@@ -6,67 +6,104 @@ import kotlinx.atomicfu.AtomicRef
 import kotlinx.atomicfu.atomic
 import net.mamoe.mirai.utils.Node.Companion.equals
 
-
-@MiraiExperimentalAPI
-inline fun <E> lockFreeLinkedListOf(vararg elements: E): LockFreeLinkedList<E> = LockFreeLinkedList<E>().apply {
-    addAll(elements)
-}
-
-@MiraiExperimentalAPI
-inline fun <E> lockFreeLinkedListOf(): LockFreeLinkedList<E> = LockFreeLinkedList<E>()
-
 /**
  * Implementation of lock-free LinkedList.
  *
  * Modifying can be performed concurrently.
- * Iterating concurrency is guaranteed. // TODO: 2019/12/13 ADD MORE
+ * Iterating concurrency is guaranteed.
  */
-@MiraiExperimentalAPI
-class LockFreeLinkedList<E> : MutableList<E>, RandomAccess {
+class LockFreeLinkedList<E> {
     private val tail: Tail<E> = Tail()
 
     private val head: Head<E> = Head(tail)
 
-    override fun add(element: E): Boolean {
+    fun add(element: E) {
         val node = element.asNode(tail)
 
         while (true) {
             val tail = head.iterateBeforeFirst { it === tail } // find the last node.
             if (tail.nextNodeRef.compareAndSet(this.tail, node)) { // ensure the last node is the last node
-                return true
+                return
             }
         }
-
-
     }
 
-    internal fun getLinkStucture(): String = buildString {
+    override fun toString(): String = "[" + buildString {
+        this@LockFreeLinkedList.forEach {
+            append(it)
+            append(", ")
+        }
+    }.dropLast(2) + "]"
+
+    @Suppress("unused")
+    internal fun getLinkStructure(): String = buildString {
         head.childIterateReturnsLastSatisfying<Node<*>>({
             append(it.toString())
             append("->")
             it.nextNode
         }, { it !is Tail })
-    }.let {
-        if (it.lastIndex > 0) {
-            it.substring(0..it.lastIndex - 2)
-        } else it
-    }
+    }.dropLast(2)
 
-    override fun remove(element: E): Boolean {
+    fun remove(element: E): Boolean {
         while (true) {
             val before = head.iterateBeforeNodeValue(element)
             val toRemove = before.nextNode
-            val next = toRemove.nextNode
             if (toRemove === tail) {
                 return false
             }
+            if (toRemove.nodeValue === null) {
+                continue
+            }
+            toRemove.nodeValue = null // logically remove: all the operations will recognize this node invalid
 
-            if (before.nextNodeRef.compareAndSet(toRemove, next)) {
+            var next: Node<E> = toRemove.nextNode
+            while (next !== tail && next.nodeValue === null) {
+                next = next.nextNode
+            }
+            if (before.nextNodeRef.compareAndSet(toRemove, next)) {// physically remove: try to fix the link
                 return true
             }
         }
     }
 
+    val size: Int get() = head.countChildIterate<Node<E>>({ it.nextNodeRef.value }, { it !is Tail }) - 1 // empty head is always included
+
+    operator fun contains(element: E): Boolean = head.iterateBeforeNodeValue(element) !== tail
+
+    @Suppress("unused")
+    fun containsAll(elements: Collection<E>): Boolean = elements.all { contains(it) }
+
+    fun isEmpty(): Boolean = head.allMatching { it.isValidElementNode().not() }
+
+    fun forEach(block: (E) -> Unit) {
+        var node: Node<E> = head
+        while (true) {
+            if (node === tail) return
+            node.letIfNotnull(block)
+            node = node.nextNode
+        }
+    }
+
+    fun addAll(elements: Collection<E>) = elements.forEach { add(it) }
+
+    @Suppress("unused")
+    fun clear() {
+        val first = head.nextNode
+        head.nextNode = tail
+        first.childIterateReturnFirstUnsatisfying({
+            val n = it.nextNode
+            it.nextNode = tail
+            it.nodeValue = null
+            n
+        }, { it !== tail }) // clear the link structure, help GC.
+    }
+
+    @Suppress("unused")
+    fun removeAll(elements: Collection<E>): Boolean = elements.all { remove(it) }
+
+    /*
+
+
     private fun removeNode(node: Node<E>): Boolean {
         if (node == tail) {
             return false
@@ -78,7 +115,7 @@ class LockFreeLinkedList<E> : MutableList<E>, RandomAccess {
             if (toRemove == tail) { // This
                 return true
             }
-            toRemove.nodeValue = null // logaically remove first, then all the operations will recognize this node invalid
+            toRemove.nodeValue = null // logically remove first, then all the operations will recognize this node invalid
 
             if (before.nextNodeRef.compareAndSet(toRemove, next)) { // physically remove: try to fix the link
                 return true
@@ -86,43 +123,264 @@ class LockFreeLinkedList<E> : MutableList<E>, RandomAccess {
         }
     }
 
-    override val size: Int
-        get() = head.countChildIterate<Node<E>>({ it.nextNodeRef.value }, { it !is Tail }) - 1 // empty head is always included
-
-    override operator fun contains(element: E): Boolean = head.iterateBeforeNodeValue(element) !== tail
-
-    override fun containsAll(elements: Collection<E>): Boolean = elements.all { contains(it) }
-
-    override operator fun get(index: Int): E {
-        require(index >= 0) { "Index must be >= 0" }
-        var i = index + 1 // 1 for head
-        return head.iterateStopOnFirst { i-- == 0 }.nodeValueRef.value ?: noSuchElement()
+    fun removeAt(index: Int): E {
+        require(index >= 0) { "index must be >= 0" }
+        val nodeBeforeIndex = head.iterateValidNodeNTimes(index)
+        val value = nodeBeforeIndex.nodeValue
+        if (value === null) noSuchElement()
+        removeNode(nodeBeforeIndex)
+        return value
     }
 
-    override fun indexOf(element: E): Int {
+    operator fun set(index: Int, element: E): E {
+        while (true) {
+            val nodeAtIndex = head.iterateValidNodeNTimes(index + 1)
+            val originalValue = nodeAtIndex.nodeValue
+            if (originalValue === null) noSuchElement() // this node has been removed.
+            if (!nodeAtIndex.nodeValueRef.compareAndSet(null, element)) { // with concurrent compatibility
+                continue
+            }
+            return originalValue
+        }
+    }
+
+    /**
+     * Find the last index of the element in the list that is [equals] to [element], with concurrent compatibility.
+     *
+     * For a typical list, say `head <- Node#1(1) <- Node#2(2) <- Node#3(3) <- Node#4(4) <- Node#5(2) <- tail`,
+     * the procedures of `lastIndexOf(2)` is:
+     *
+     * 1. Iterate each element, until 2 is found, accumulate the index found, which is 1
+     * 2. Search again from the first matching element, which is Node#2
+     * 3. Accumulate the index found.
+     * 4. Repeat 2,3 until the `tail` is reached.
+     *
+     * Concurrent changes may influence the result.
+     */
+    fun lastIndexOf(element: E): Int {
+        var lastMatching: Node<E> = head
+        var searchStartingFrom: Node<E> = lastMatching
+        var index = 0 // accumulated index from each search
+
+        findTheLastMatchingElement@ while (true) { // iterate to find the last matching element.
+            var timesOnThisTurn = if (searchStartingFrom === head) -1 else 0 // ignore the head
+            val got = searchStartingFrom.nextNode.iterateBeforeFirst { timesOnThisTurn++; it.nodeValue == element }
+            // find the first match starting from `searchStartingFrom`
+
+            if (got.isTail()) break@findTheLastMatchingElement // no further elements
+            check(timesOnThisTurn >= 0) { "Internal check failed: too many times ran: $timesOnThisTurn" }
+
+            searchStartingFrom = got.nextNode
+            index += timesOnThisTurn
+
+            if (!got.isRemoved()) lastMatching = got
+        }
+
+        if (!lastMatching.isValidElementNode()) {
+            // found is invalid means not found
+            return -1
+        }
+
+        return index
+    }
+     */
+
+    /*
+    override fun listIterator(): MutableListIterator<E> = listIterator0(0)
+    override fun listIterator(index: Int): MutableListIterator<E> = listIterator0(index)
+
+    @Suppress("NOTHING_TO_INLINE")
+    private inline fun listIterator0(index: Int): MutableListIterator<E> {
+        var first: Node<E> = head
+        repeat(index) {
+            first = first.nextNode
+            if (first === tail) noSuchElement()
+        }
+        return object : MutableListIterator<E> {
+            var currentNode: Node<E>
+                get() = currentNodeRef.value
+                set(value) {
+                    currentNodeRef.value = value
+                }
+
+            private val currentNodeRef: AtomicRef<Node<E>> = atomic(first) // concurrent compatibility
+
+            override fun nextIndex(): Int = indexOfNode(currentNode)
+
+
+            // region previous
+
+            var previousNode: Node<E>
+                get() = previousNodeRef.value
+                set(value) {
+                    previousNodeRef.value = value
+                }
+            private val previousNodeRef: AtomicRef<Node<E>> = atomic(head) // concurrent compatibility
+            private val previousNodeIndexRef: AtomicInt = atomic(-1) // concurrent compatibility
+            private val currentNodeAtTheMomentWhenPreviousNodeIsUpdated: AtomicRef<Node<E>> = atomic(currentNode)
+
+            override fun hasPrevious(): Boolean = previousIndex() == -1
+
+            private fun updatePrevious(): Boolean {
+                while (true) {
+                    val localNodeAtTheMomentWhenPreviousNodeIsUpdated = currentNode
+                    var i = -1 // head
+                    var lastSatisfying: Node<E>? = null
+                    val foundNode = currentNode.childIterateReturnsLastSatisfying({ it.nextNode }, {
+                        i++
+                        if (it.isValidElementNode()) {
+                            lastSatisfying = it
+                        }
+                        it != currentNode
+                    })
+
+                    if (localNodeAtTheMomentWhenPreviousNodeIsUpdated !== currentNode) {
+                        continue // current is concurrently changed, must retry
+                    }
+
+                    if (!foundNode.isValidElementNode()) {
+                        // Current node is not found in the list, meaning it had been removed concurrently
+                        previousNode = head
+                        previousNodeIndexRef.value = -1
+                        return false
+                    }
+
+                    if (lastSatisfying === null) {
+                        // All the previous nodes are logically removed.
+                        previousNode = head
+                        previousNodeIndexRef.value = -1
+                        return false
+                    }
+
+                    currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value = localNodeAtTheMomentWhenPreviousNodeIsUpdated
+                    previousNode = lastSatisfying!! // false positive nullable warning
+                    previousNodeIndexRef.value = i
+                    return true
+                }
+            }
+
+            override fun previous(): E {
+                if (currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head) {
+                    // node list have been changed.
+                    if (!updatePrevious()) noSuchElement()
+                }
+                while (true) {
+                    val value = previousNode.nodeValue
+                    if (value != null) {
+                        currentNode = previousNode
+                        currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head
+                        return value
+                    } else if (!updatePrevious()) noSuchElement()
+                }
+            }
+
+            override fun previousIndex(): Int {
+                if (currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head) {
+                    // node list have been changed.
+                    if (!updatePrevious()) noSuchElement()
+                }
+                while (true) {
+                    val value = previousNodeIndexRef.value
+                    if (value != -1) return value
+                    else if (!updatePrevious()) noSuchElement()
+                }
+            }
+            // endregion
+
+            override fun add(element: E) {
+                val toAdd = element.asNode(tail)
+                while (true) {
+                    val next = currentNode.nextNode
+                    toAdd.nextNode = next
+                    if (currentNode.nextNodeRef.compareAndSet(next, toAdd)) { // ensure the link is not changed
+                        currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value = head
+                        return
+                    }
+                }
+            }
+
+            override fun hasNext(): Boolean {
+                if (currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head) {
+                    // node list have been changed.
+                    if (!updatePrevious()) noSuchElement()
+                }
+                return currentNode.nextNode !== tail
+            }
+
+            override fun next(): E {
+                while (true) {
+                    if (currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head) {
+                        // node list have been changed.
+                        if (!updatePrevious()) noSuchElement()
+                    }
+                    val nextNodeValue = currentNode.nextNode.nodeValue
+                    if (nextNodeValue !== null) {
+                        currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value = head
+                        return nextNodeValue
+                    }
+                }
+            }
+
+            override fun remove() {
+                if (!removeNode(currentNode)) { // search from head onto the node, concurrent compatibility
+                    noSuchElement()
+                }
+                currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value = head
+            }
+
+            override fun set(element: E) {
+                if (currentNodeAtTheMomentWhenPreviousNodeIsUpdated.value == head) {
+                    // node list have been changed.
+                    if (!updatePrevious()) noSuchElement()
+                }
+
+            }
+
+        }
+    }
+
+    override fun subList(fromIndex: Int, toIndex: Int): MutableList<E> {
+
+    }
+    */
+
+    /*
+    operator fun get(index: Int): E {
+        require(index >= 0) { "Index must be >= 0" }
+        var i = index + 1 // 1 for head
+        return head.iterateStopOnFirst { i-- == 0 }.nodeValue ?: noSuchElement()
+    }
+
+    fun indexOf(element: E): Int {
         var i = -1 // head
         if (!head.iterateStopOnFirst {
                 i++
-                it.nodeValueRef.value == element
+                it.nodeValue == element
             }.isValidElementNode()) {
             return -1
         }
         return i - 1 // iteration is stopped at the next node
     }
 
-    override fun isEmpty(): Boolean = head.allMatching { it.nodeValueRef.value == null }
+    private fun indexOfNode(node: Node<E>): Int {
+        var i = -1 // head
+        if (!head.iterateStopOnFirst {
+                i++
+                it == node
+            }.isValidElementNode()) {
+            return -1
+        }
+        return i - 1 // iteration is stopped at the next node
+    }
 
-    /**
-     * Create a concurrent-unsafe iterator
-     */
-    override operator fun iterator(): MutableIterator<E> = object : MutableIterator<E> {
+    operator fun iterator(): MutableIterator<E> = object : MutableIterator<E> {
         var currentNode: Node<E>
-            get() = currentNoderef.value
+            get() = currentNodeRef.value
             set(value) {
-                currentNoderef.value = value
+                currentNodeRef.value = value
             }
 
-        private val currentNoderef: AtomicRef<Node<E>> = atomic(head) // concurrent compatibility
+        private val currentNodeRef: AtomicRef<Node<E>> = atomic(head) // concurrent compatibility
 
         /**
          * Check if
@@ -156,103 +414,26 @@ class LockFreeLinkedList<E> : MutableList<E>, RandomAccess {
             }
         }
     }
-
-    /**
-     * Find the last index of the element in the list that is [equals] to [element], with concurrent compatibility.
-     *
-     * For a typical list, say `head <- Node#1(1) <- Node#2(2) <- Node#3(3) <- Node#4(4) <- Node#5(2) <- tail`,
-     * the procedures of `lastIndexOf(2)` is:
-     *
-     * 1. Iterate each element, until 2 is found, accumulate the index found, which is 1
-     * 2. Search again from the first matching element, which is Node#2
-     * 3. Accumulate the index found.
-     * 4. Repeat 2,3 until the `tail` is reached.
-     *
-     * Concurrent changes may influence the result.
-     * While searching,
-     *
-     */
-    override fun lastIndexOf(element: E): Int {
-        var lastMatching: Node<E> = head
-        var searchStartingFrom: Node<E> = lastMatching
-        var index = 0 // accumulated index from each search
-
-        findTheLastMatchingElement@ while (true) { // iterate to find the last matching element.
-            var timesOnThisTurn = if (searchStartingFrom === head) -1 else 0 // ignore the head
-            val got = searchStartingFrom.nextNode.iterateBeforeFirst { timesOnThisTurn++; it.nodeValue == element }
-            // find the first match starting from `searchStartingFrom`
-
-            if (got.isTail()) break@findTheLastMatchingElement // no further elements
-            check(timesOnThisTurn >= 0) { "Internal check failed: too many times ran: $timesOnThisTurn" }
-
-            searchStartingFrom = got.nextNode
-            index += timesOnThisTurn
-
-            if (!got.isRemoved()) lastMatching = got //record the lastMatching only if got is not removed.
-        }
-
-        if (!lastMatching.isValidElementNode()) {
-            // found is invalid means not found
-            return -1
-        }
-
-        return index
-    }
-
-    override fun listIterator(): MutableListIterator<E> = listIterator0(0)
-    override fun listIterator(index: Int): MutableListIterator<E> = listIterator0(index)
-
-    @Suppress("NOTHING_TO_INLINE")
-    internal inline fun listIterator0(index: Int): MutableListIterator<E> {
-        TODO()
-    }
-
-    override fun subList(fromIndex: Int, toIndex: Int): MutableList<E> {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-
-    override fun add(index: Int, element: E) {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun addAll(index: Int, elements: Collection<E>): Boolean {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun addAll(elements: Collection<E>): Boolean {
-        elements.forEach { add(it) }
-        return true
-    }
-
-    override fun clear() {
-        head.nextNode = tail
-
-        // TODO: 2019/12/13 check ?
-    }
-
-    override fun removeAll(elements: Collection<E>): Boolean {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun removeAt(index: Int): E {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun retainAll(elements: Collection<E>): Boolean {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override operator fun set(index: Int, element: E): E {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-
-    // NO INLINE: currently exceptions thrown in a inline function cannot be traced
-    private fun noSuchElement(): Nothing = throw NoSuchElementException()
-
+    */
 }
 
+/**
+ * Returns a [List] containing all the elements in [this] in the same order
+ */
+fun <E> LockFreeLinkedList<E>.toList(): List<E> = toMutableList()
+
+/**
+ * Returns a [MutableList] containing all the elements in [this] in the same order
+ */
+fun <E> LockFreeLinkedList<E>.toMutableList(): MutableList<E> {
+    val list = mutableListOf<E>()
+    this.forEach { list.add(it) }
+    return list
+}
+
+
+// region internal
+
 @Suppress("NOTHING_TO_INLINE")
 private inline fun <E> E.asNode(nextNode: Node<E>): Node<E> = Node(nextNode).apply { nodeValueRef.value = this@asNode }
 
@@ -280,7 +461,7 @@ private inline fun <N : Node<*>> N.childIterateReturnsLastSatisfying(iterator: (
  * Self-iterate using the [iterator], until [mustBeTrue] returns `false`.
  * Returns the element at the first time when the [mustBeTrue] returns `false`
  */
-private inline fun <E> E.childIterateReturnFirstUnsitisfying(iterator: (E) -> E, mustBeTrue: (E) -> Boolean): E {
+private inline fun <E> E.childIterateReturnFirstUnsatisfying(iterator: (E) -> E, mustBeTrue: (E) -> Boolean): E {
     if (!mustBeTrue(this)) return this
     var value: E = this
 
@@ -318,14 +499,12 @@ private inline fun <E> E.countChildIterate(iterator: (E) -> E, mustBeTrue: (E) -
 
 private class Head<E>(
     nextNode: Node<E>
-) : Node<E>(nextNode) {
-
-}
+) : Node<E>(nextNode)
 
 private open class Node<E>(
     nextNode: Node<E>?
 ) {
-    internal val id: Int = nextId();
+    internal val id: Int = nextId()
 
     companion object {
         private val idCount = atomic(0)
@@ -349,6 +528,11 @@ private open class Node<E>(
     @Suppress("LeakingThis")
     val nextNodeRef: AtomicRef<Node<E>> = atomic(nextNode ?: this)
 
+    inline fun <R> letIfNotnull(block: (E) -> R): R? {
+        val value = this.nodeValue
+        return if (value !== null) block(value) else null
+    }
+
     /**
      * Short cut for accessing [nextNodeRef]
      */
@@ -360,38 +544,10 @@ private open class Node<E>(
 
 
     /**
-     * Returns the former node of the last node whence [filter] returnes true
+     * Returns the former node of the last node whence [filter] returns true
      */
     inline fun iterateBeforeFirst(filter: (Node<E>) -> Boolean): Node<E> =
-        this.childIterateReturnsLastSatisfying<Node<E>>({ it.nextNode }, { !filter(it) })
-
-    /**
-     * Returns the last node whence [filter] returnes true.
-     */
-    inline fun iterateStopOnFirst(filter: (Node<E>) -> Boolean): Node<E> =
-        iterateBeforeFirst(filter).nextNode
-
-
-    /**
-     * Returns the former node of next node whose value is not null.
-     * [Tail] is returned if no node is found
-     */
-    @Suppress("NOTHING_TO_INLINE")
-    inline fun iterateBeforeNotnull(): Node<E> = iterateBeforeFirst { it.nodeValue != null }
-
-    /**
-     * Returns the next node which is not [Tail] or [Head] and with a notnull value.
-     * [Tail] is returned if no node is found
-     */
-    @Suppress("NOTHING_TO_INLINE")
-    inline fun nextValidElement(): Node<E> = this.iterateBeforeFirst { !it.isValidElementNode() }
-
-    /**
-     * Returns the next node whose value is not null.
-     * [Tail] is returned if no node is found
-     */
-    @Suppress("NOTHING_TO_INLINE")
-    inline fun nextNotnull(): Node<E> = this.iterateBeforeFirst { it.nodeValueRef.value == null }
+        this.childIterateReturnsLastSatisfying({ it.nextNode }, { !filter(it) })
 
     /**
      * Check if all the node which is not [Tail] matches the [condition]
@@ -399,7 +555,7 @@ private open class Node<E>(
      * Head, which is this, is also being tested.
      * [Tail], is not being tested.
      */
-    inline fun allMatching(condition: (Node<E>) -> Boolean): Boolean = this.childIterateReturnsLastSatisfying<Node<E>>({ it.nextNode }, condition) !is Tail
+    inline fun allMatching(condition: (Node<E>) -> Boolean): Boolean = this.childIterateReturnsLastSatisfying({ it.nextNode }, condition) !is Tail
 
     /**
      * Stop on and returns the former element of the element that is [equals] to the [element]
@@ -408,21 +564,10 @@ private open class Node<E>(
      */
     @Suppress("NOTHING_TO_INLINE")
     inline fun iterateBeforeNodeValue(element: E): Node<E> = this.iterateBeforeFirst { it.nodeValueRef.value == element }
-
-    /**
-     * Stop on and returns the element that is [equals] to the [element]
-     *
-     * E.g.: for `head <- 1 <- 2 <- 3 <- tail`, `iterateStopOnNodeValue(2)` returns the node whose value is 2
-     */
-    @Suppress("NOTHING_TO_INLINE")
-    inline fun iterateStopOnNodeValue(element: E): Node<E> = this.iterateBeforeNodeValue(element).nextNode
 }
 
 private open class Tail<E> : Node<E>(null)
 
-@Suppress("unused")
-private fun <E> AtomicRef<out Node<out E>>.getNodeValue(): E? = if (this.value is Tail) null else this.value.nodeValueRef.value
-
 @Suppress("NOTHING_TO_INLINE")
 private inline fun Node<*>.isValidElementNode(): Boolean = !isHead() && !isTail() && !isRemoved()
 
@@ -433,4 +578,6 @@ private inline fun Node<*>.isHead(): Boolean = this is Head
 private inline fun Node<*>.isTail(): Boolean = this is Tail
 
 @Suppress("NOTHING_TO_INLINE")
-private inline fun Node<*>.isRemoved(): Boolean = this.nodeValue == null
\ No newline at end of file
+private inline fun Node<*>.isRemoved(): Boolean = this.nodeValue == null
+
+// en dregion
\ No newline at end of file
diff --git a/mirai-core/src/jvmTest/kotlin/net/mamoe/mirai/utils/LockFreeLinkedListTest.kt b/mirai-core/src/jvmTest/kotlin/net/mamoe/mirai/utils/LockFreeLinkedListTest.kt
index 1e3e8ed0d..976b65e32 100644
--- a/mirai-core/src/jvmTest/kotlin/net/mamoe/mirai/utils/LockFreeLinkedListTest.kt
+++ b/mirai-core/src/jvmTest/kotlin/net/mamoe/mirai/utils/LockFreeLinkedListTest.kt
@@ -4,17 +4,18 @@ package net.mamoe.mirai.utils
 
 import kotlinx.coroutines.*
 import net.mamoe.mirai.test.shouldBeEqualTo
-import net.mamoe.mirai.test.shouldBeFalse
 import net.mamoe.mirai.test.shouldBeTrue
 import org.junit.Test
 import kotlin.system.exitProcess
-import kotlin.test.*
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
 
 @MiraiExperimentalAPI
 internal class LockFreeLinkedListTest {
     init {
         GlobalScope.launch {
-            delay(5000)
+            delay(30 * 1000)
             exitProcess(-100)
         }
     }
@@ -27,26 +28,41 @@ internal class LockFreeLinkedListTest {
         list.add(3)
         list.add(4)
 
-        assertEquals(list[0], 1, "Failed on list[0]")
-        assertEquals(list[1], 2, "Failed on list[1]")
-        assertEquals(list[2], 3, "Failed on list[2]")
-        assertEquals(list[3], 4, "Failed on list[3]")
+        list.size shouldBeEqualTo 4
     }
 
     @Test
-    fun addAndGetSingleConcurrent() {
+    fun addAndGetConcurrent() = runBlocking {
+        //withContext(Dispatchers.Default){
         val list = LockFreeLinkedList<Int>()
-        val add = GlobalScope.async { list.concurrentAdd(1000, 10, 1) }
-        val remove = GlobalScope.async {
-            add.join()
-            list.concurrentDo(100, 10) {
-                remove(1)
-            }
+
+        list.concurrentAdd(1000, 10, 1)
+        list.size shouldBeEqualTo 1000 * 10
+
+        list.concurrentDo(100, 10) {
+            remove(1).shouldBeTrue()
         }
-        runBlocking {
-            joinAll(add, remove)
+
+        list.size shouldBeEqualTo 1000 * 10 - 100 * 10
+        //}
+    }
+
+    @Test
+    fun addAndGetMassConcurrentAccess() = runBlocking {
+        val list = LockFreeLinkedList<Int>()
+
+        val addJob = async { list.concurrentAdd(5000, 10, 1) }
+
+        delay(10) // let addJob fly
+        if (addJob.isCompleted) {
+            error("Number of elements are not enough")
         }
-        assertEquals(1000 * 10 - 100 * 10, list.size)
+        list.concurrentDo(1000, 10) {
+            remove(1).shouldBeTrue()
+        }
+        addJob.join()
+
+        list.size shouldBeEqualTo 5000 * 10 - 1000 * 10
     }
 
     @Test
@@ -65,179 +81,113 @@ internal class LockFreeLinkedListTest {
         assertEquals(1, list.size)
     }
 
-    @Test
-    fun getSize() {
-        val list = lockFreeLinkedListOf(1, 2, 3, 4, 5)
-        assertEquals(5, list.size)
-
-        val list2 = lockFreeLinkedListOf<Unit>()
-        assertEquals(0, list2.size)
-    }
-
-    @Test
-    fun contains() {
-        val list = lockFreeLinkedListOf<Int>()
-        assertFalse { list.contains(0) }
-
-        list.add(0)
-        assertTrue { list.contains(0) }
-    }
-
-    @Test
-    fun containsAll() {
-        var list = lockFreeLinkedListOf(1, 2, 3)
-        assertTrue { list.containsAll(listOf(1, 2, 3)) }
-        assertTrue { list.containsAll(listOf()) }
-
-        list = lockFreeLinkedListOf(1, 2)
-        assertFalse { list.containsAll(listOf(1, 2, 3)) }
-
-        list = lockFreeLinkedListOf()
-        assertTrue { list.containsAll(listOf()) }
-        assertFalse { list.containsAll(listOf(1)) }
-    }
-
-    @Test
-    fun indexOf() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2, 3, 3)
-        assertEquals(0, list.indexOf(1))
-        assertEquals(2, list.indexOf(3))
-
-        assertEquals(-1, list.indexOf(4))
-    }
-
-    @Test
-    fun isEmpty() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf()
-        list.isEmpty().shouldBeTrue()
-
-        list.add(1)
-        list.isEmpty().shouldBeFalse()
-    }
-
-    @Test
-    fun iterator() {
-        var list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2)
-        list.forEach {
-            it shouldBeEqualTo 2
-        }
-
-        list = lockFreeLinkedListOf(1, 2)
-        list.joinToString { it.toString() } shouldBeEqualTo "1, 2"
-
-
-        list = lockFreeLinkedListOf(1, 2)
-        val iterator = list.iterator()
-        iterator.remove()
-        var reached = false
-        for (i in iterator) {
-            i shouldBeEqualTo 2
-            reached = true
-        }
-        reached shouldBeEqualTo true
-
-        list.joinToString { it.toString() } shouldBeEqualTo "2"
-        iterator.remove()
-        assertFailsWith<NoSuchElementException> { iterator.remove() }
-    }
-
-    @Test
-    fun `lastIndexOf of exact 1 match at first`() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2, 1)
-        list.lastIndexOf(2) shouldBeEqualTo 0
-    }
-
-    @Test
-    fun `lastIndexOf of exact 1 match`() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2)
-        list.lastIndexOf(2) shouldBeEqualTo 1
-    }
-
-    @Test
-    fun `lastIndexOf of multiply matches`() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2, 2)
-        list.lastIndexOf(2) shouldBeEqualTo 2
-    }
-
-    @Test
-    fun `lastIndexOf of no match`() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2)
-        list.lastIndexOf(3) shouldBeEqualTo -1
-    }
-
-    @Test
-    fun `lastIndexOf of many elements`() {
-        val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 4, 2, 3, 4, 5)
-        list.lastIndexOf(4) shouldBeEqualTo 4
-    }
-
-
-/*
-    companion object{
-        @JvmStatic
-        fun main(vararg args: String) {
-            LockFreeLinkedListTest().`lastIndexOf of many elements`()
-        }
-    }*/
-
-    @Test
-    fun listIterator() {
-    }
-
-    @Test
-    fun testListIterator() {
-    }
-
-    @Test
-    fun subList() {
-    }
-
-    @Test
-    fun testAdd() {
-    }
-
     @Test
     fun addAll() {
-    }
-
-    @Test
-    fun testAddAll() {
+        val list = LockFreeLinkedList<Int>()
+        list.addAll(listOf(1, 2, 3, 4, 5))
+        list.size shouldBeEqualTo 5
     }
 
     @Test
     fun clear() {
+        val list = LockFreeLinkedList<Int>()
+        list.addAll(listOf(1, 2, 3, 4, 5))
+        list.size shouldBeEqualTo 5
+        list.clear()
+        list.size shouldBeEqualTo 0
+    }
+
+    @UseExperimental(ExperimentalUnsignedTypes::class)
+    @Test
+    fun withInlineClassElements() {
+        val list = LockFreeLinkedList<UInt>()
+        list.addAll(listOf(1u, 2u, 3u, 4u, 5u))
+        list.size shouldBeEqualTo 5
+
+        list.toString() shouldBeEqualTo "[1, 2, 3, 4, 5]"
+    }
+
+    /*
+    @Test
+    fun indexOf() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2, 3, 3)
+    assertEquals(0, list.indexOf(1))
+    assertEquals(2, list.indexOf(3))
+
+    assertEquals(-1, list.indexOf(4))
     }
 
     @Test
-    fun removeAll() {
+    fun iterator() {
+    var list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2)
+    list.forEach {
+    it shouldBeEqualTo 2
+    }
+
+    list = lockFreeLinkedListOf(1, 2)
+    list.joinToString { it.toString() } shouldBeEqualTo "1, 2"
+
+
+    list = lockFreeLinkedListOf(1, 2)
+    val iterator = list.iterator()
+    iterator.remove()
+    var reached = false
+    for (i in iterator) {
+    i shouldBeEqualTo 2
+    reached = true
+    }
+    reached shouldBeEqualTo true
+
+    list.joinToString { it.toString() } shouldBeEqualTo "2"
+    iterator.remove()
+    assertFailsWith<NoSuchElementException> { iterator.remove() }
     }
 
     @Test
-    fun removeAt() {
+    fun `lastIndexOf of exact 1 match at first`() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2, 1)
+    list.lastIndexOf(2) shouldBeEqualTo 0
     }
 
     @Test
-    fun retainAll() {
+    fun `lastIndexOf of exact 1 match`() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2)
+    list.lastIndexOf(2) shouldBeEqualTo 1
     }
 
     @Test
-    fun set() {
+    fun `lastIndexOf of multiply matches`() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 2, 2)
+    list.lastIndexOf(2) shouldBeEqualTo 2
     }
+
+    @Test
+    fun `lastIndexOf of no match`() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(2)
+    list.lastIndexOf(3) shouldBeEqualTo -1
+    }
+
+    @Test
+    fun `lastIndexOf of many elements`() {
+    val list: LockFreeLinkedList<Int> = lockFreeLinkedListOf(1, 4, 2, 3, 4, 5)
+    list.lastIndexOf(4) shouldBeEqualTo 4
+    }
+
+     */
 }
 
-internal fun withTimeoutBlocking(timeout: Long = 500L, block: suspend () -> Unit) = runBlocking { withTimeout(timeout) { block() } }
-
 @MiraiExperimentalAPI
-internal suspend fun <E> LockFreeLinkedList<E>.concurrentAdd(numberOfCoroutines: Int, timesOfAdd: Int, element: E) =
+internal suspend inline fun <E> LockFreeLinkedList<E>.concurrentAdd(numberOfCoroutines: Int, timesOfAdd: Int, element: E) =
     concurrentDo(numberOfCoroutines, timesOfAdd) { add(element) }
 
 @MiraiExperimentalAPI
-internal suspend fun <E : LockFreeLinkedList<*>> E.concurrentDo(numberOfCoroutines: Int, timesOfAdd: Int, todo: E.() -> Unit) = coroutineScope {
-    repeat(numberOfCoroutines) {
-        launch {
-            repeat(timesOfAdd) {
-                todo()
+internal suspend inline fun <E : LockFreeLinkedList<*>> E.concurrentDo(numberOfCoroutines: Int, timesOfAdd: Int, crossinline todo: E.() -> Unit) =
+    coroutineScope {
+        repeat(numberOfCoroutines) {
+            launch {
+                repeat(timesOfAdd) {
+                    todo()
+                }
             }
         }
-    }
-}
\ No newline at end of file
+    }
\ No newline at end of file