Merge remote-tracking branch 'origin/master'

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/event/MessageSubscribers.kt

@@ -28,6 +28,8 @@ import kotlin.contracts.contract
 
 /**
  * 订阅来自所有 [Bot] 的所有联系人的消息事件. 联系人可以是任意群或任意好友或临时会话.
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -49,6 +51,8 @@ inline fun <R> CoroutineScope.subscribeMessages(crossinline listeners: MessageSu
 
 /**
  * 订阅来自所有 [Bot] 的所有群消息事件
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -65,6 +69,8 @@ inline fun <R> CoroutineScope.subscribeGroupMessages(crossinline listeners: Mess
 
 /**
  * 订阅来自所有 [Bot] 的所有好友消息事件
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -81,6 +87,8 @@ inline fun <R> CoroutineScope.subscribeFriendMessages(crossinline listeners: Mes
 
 /**
  * 订阅来自这个 [Bot] 的所有联系人的消息事件. 联系人可以是任意群或任意好友或临时会话.
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -97,6 +105,8 @@ inline fun <R> Bot.subscribeMessages(crossinline listeners: MessageSubscribersBu
 
 /**
  * 订阅来自这个 [Bot] 的所有群消息事件
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -113,6 +123,8 @@ inline fun <R> Bot.subscribeGroupMessages(crossinline listeners: MessageSubscrib
 
 /**
  * 订阅来自这个 [Bot] 的所有好友消息事件.
+ *
+ * @see CoroutineScope.incoming
  */
 @UseExperimental(ExperimentalContracts::class)
 @MessageDsl
@@ -129,9 +141,15 @@ inline fun <R> Bot.subscribeFriendMessages(crossinline listeners: MessageSubscri
 
 /**
  * 返回一个指定事件的接收通道
+ *
+ * @param capacity 同 [Channel] 的参数, 参见 [Channel.Factory] 中的常量.
+ *
+ * @see subscribeFriendMessages
+ * @see subscribeMessages
+ * @see subscribeGroupMessages
  */
-inline fun <reified E : Event> Bot.incoming(): ReceiveChannel<E> {
+inline fun <reified E : Event> CoroutineScope.incoming(capacity: Int = Channel.RENDEZVOUS): ReceiveChannel<E> {
-    return Channel<E>(8).apply {
+    return Channel<E>(capacity).apply {
         subscribeAlways<E> {
             send(this)
         }

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/event/internal/InternalEventListeners.kt

@@ -90,6 +90,15 @@ internal object EventListenerManager {
 
     private val lock = atomic(false)
 
+    private fun setLockValue(value: Boolean) {
+        lock.value = value
+    }
+
+    @Suppress("BooleanLiteralArgument")
+    private fun trySetLockTrue(): Boolean {
+        return lock.compareAndSet(false, true)
+    }
+
     @Suppress("UNCHECKED_CAST", "BooleanLiteralArgument")
     internal tailrec fun <E : Event> get(clazz: KClass<out E>): EventListeners<E> {
         registries.forEach {
@@ -97,10 +106,10 @@ internal object EventListenerManager {
                 return it.listeners as EventListeners<E>
             }
         }
-        if (lock.compareAndSet(false, true)) {
+        if (trySetLockTrue()) {
             val registry = Registry(clazz, EventListeners())
             registries.addLast(registry)
-            lock.value = false
+            setLockValue(false)
             return registry.listeners as EventListeners<E>
         }
         return get(clazz)