1 files changed, 121 insertions, 0 deletions
diff --git a/src/main/java/org/traccar/handler/network/AcknowledgementHandler.java b/src/main/java/org/traccar/handler/network/AcknowledgementHandler.java
new file mode 100644
index 000000000..e87f5d34c
--- /dev/null
+++ b/src/main/java/org/traccar/handler/network/AcknowledgementHandler.java
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2023 Anton Tananaev (anton@traccar.org)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.traccar.handler.network;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelOutboundHandlerAdapter;
+import io.netty.channel.ChannelPromise;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+
+public class AcknowledgementHandler extends ChannelOutboundHandlerAdapter {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(AcknowledgementHandler.class);
+
+    public interface Event {
+    }
+
+    public static class EventReceived implements Event {
+    }
+
+    public static class EventDecoded implements Event {
+        private final Collection<Object> objects;
+
+        public EventDecoded(Collection<Object> objects) {
+            this.objects = objects;
+        }
+
+        public Collection<Object> getObjects() {
+            return objects;
+        }
+    }
+
+    public static class EventHandled implements Event {
+        private final Object object;
+
+        public EventHandled(Object object) {
+            this.object = object;
+        }
+
+        public Object getObject() {
+            return object;
+        }
+    }
+
+    private static final class Entry {
+        private final Object message;
+        private final ChannelPromise promise;
+
+        private Entry(Object message, ChannelPromise promise) {
+            this.message = message;
+            this.promise = promise;
+        }
+
+        public Object getMessage() {
+            return message;
+        }
+
+        public ChannelPromise getPromise() {
+            return promise;
+        }
+    }
+
+    private List<Entry> queue;
+    private final Set<Object> waiting = new HashSet<>();
+
+    @Override
+    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
+        List<Entry> output = new LinkedList<>();
+        synchronized (this) {
+            if (msg instanceof Event) {
+                if (msg instanceof EventReceived) {
+                    LOGGER.debug("Event received");
+                    if (queue == null) {
+                        queue = new LinkedList<>();
+                    }
+                } else if (msg instanceof EventDecoded) {
+                    EventDecoded event = (EventDecoded) msg;
+                    LOGGER.debug("Event decoded {}", event.getObjects().size());
+                    waiting.addAll(event.getObjects());
+                } else if (msg instanceof EventHandled) {
+                    EventHandled event = (EventHandled) msg;
+                    LOGGER.debug("Event handled");
+                    waiting.remove(event.getObject());
+                }
+                if (!(msg instanceof EventReceived) && waiting.isEmpty()) {
+                    output.addAll(queue);
+                    queue = null;
+                }
+            } else if (queue != null) {
+                LOGGER.debug("Message queued");
+                queue.add(new Entry(msg, promise));
+            } else {
+                LOGGER.debug("Message sent");
+                output.add(new Entry(msg, promise));
+            }
+        }
+        for (Entry entry : output) {
+            ctx.write(entry.getMessage(), entry.getPromise());
+        }
+    }
+
+}