[ci skip] refactor: Refactor monitors into EventFlow

2 files changed, 108 insertions, 9 deletions

diff --git a/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/flow/EventFlow.kt b/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/flow/EventFlow.kt
new file mode 100644
index 00000000..5d9af9ec
--- /dev/null
+++ b/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/flow/EventFlow.kt
@@ -0,0 +1,99 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 atlarge-research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.atlarge.odcsim.flow
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.InternalCoroutinesApi
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.channels.SendChannel
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.FlowCollector
+import kotlinx.coroutines.flow.consumeAsFlow
+import java.util.WeakHashMap
+
+/**
+ * A [Flow] that can be used to emit events.
+ */
+public interface EventFlow<T> : Flow<T> {
+    /**
+     * Emit the specified [event].
+     */
+    public fun emit(event: T)
+
+    /**
+     * Close the flow.
+     */
+    public fun close()
+}
+
+/**
+ * Creates a new [EventFlow].
+ */
+@Suppress("FunctionName")
+public fun <T> EventFlow(): EventFlow<T> = EventFlowImpl()
+
+/**
+ * Internal implementation of the [EventFlow] class.
+ */
+@OptIn(ExperimentalCoroutinesApi::class, FlowPreview::class)
+private class EventFlowImpl<T> : EventFlow<T> {
+    private var closed: Boolean = false
+    private val subscribers = WeakHashMap<SendChannel<T>, Unit>()
+
+    override fun emit(event: T) {
+        synchronized(this) {
+            for ((chan, _) in subscribers) {
+                chan.offer(event)
+            }
+        }
+    }
+
+    override fun close() {
+        synchronized(this) {
+            closed = true
+
+            for ((chan, _) in subscribers) {
+                chan.close()
+            }
+        }
+    }
+
+    @InternalCoroutinesApi
+    override suspend fun collect(collector: FlowCollector<T>) {
+        val channel: Channel<T>
+        synchronized(this) {
+            if (closed) {
+                return
+            }
+
+            channel = Channel(Channel.UNLIMITED)
+            subscribers[channel] = Unit
+        }
+        channel.consumeAsFlow().collect(collector)
+    }
+
+    override fun toString(): String = "EventFlow"
+}
diff --git a/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/signal/Signal.kt b/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/flow/StateFlow.kt
index da6298a3..429d932b 100644
--- a/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/signal/Signal.kt
+++ b/odcsim/odcsim-api/src/main/kotlin/com/atlarge/odcsim/flow/StateFlow.kt
@@ -22,7 +22,7 @@
  * SOFTWARE.
  */
 
-package com.atlarge.odcsim.signal
+package com.atlarge.odcsim.flow
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.FlowPreview
@@ -40,9 +40,9 @@ import kotlinx.coroutines.flow.asFlow
  * in the future, but is not available yet.
  * See: https://github.com/Kotlin/kotlinx.coroutines/pull/1354
  */
-public interface Signal<T> : Flow<T> {
+public interface StateFlow<T> : Flow<T> {
     /**
-     * The current value of this signal.
+     * The current value of this flow.
      *
      * Setting a value that is [equal][Any.equals] to the previous one does nothing.
      */
@@ -50,23 +50,23 @@ public interface Signal<T> : Flow<T> {
 }
 
 /**
- * Creates a [Signal] with a given initial [value].
+ * Creates a [StateFlow] with a given initial [value].
  */
 @Suppress("FunctionName")
-public fun <T> Signal(value: T): Signal<T> = SignalImpl(value)
+public fun <T> StateFlow(value: T): StateFlow<T> = StateFlowImpl(value)
 
 /**
- * Internal implementation of the [Signal] interface.
+ * Internal implementation of the [StateFlow] interface.
  */
-private class SignalImpl<T>(initialValue: T) : Signal<T> {
+private class StateFlowImpl<T>(initialValue: T) : StateFlow<T> {
     /**
-     * The [BroadcastChannel] to back this signal.
+     * The [BroadcastChannel] to back this flow.
      */
     @OptIn(ExperimentalCoroutinesApi::class)
     private val chan = BroadcastChannel<T>(Channel.CONFLATED)
 
     /**
-     * The internal [Flow] backing this signal.
+     * The internal [Flow] backing this flow.
      */
     @OptIn(FlowPreview::class)
     private val flow = chan.asFlow()