1 files changed, 65 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/result/EventStream.java b/container-search/src/main/java/com/yahoo/search/result/EventStream.java
new file mode 100644
index 00000000000..84ef9a8ee86
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/result/EventStream.java
@@ -0,0 +1,65 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.result;
+
+import com.yahoo.processing.response.DefaultIncomingData;
+
+/**
+ * A stream of events which can be rendered as Server-Sent Events (SSE).
+ *
+ * @author lesters
+ */
+public class EventStream extends HitGroup {
+
+    private int eventCount = 0;
+
+    public static final String DEFAULT_EVENT_TYPE = "token";
+
+    private EventStream(String id, DefaultIncomingData<Hit> incomingData) {
+        super(id, new Relevance(1), incomingData);
+        this.setOrdered(true);  // avoid hit group ordering - important as sequence as inserted should be kept
+    }
+
+    public static EventStream create(String id) {
+        DefaultIncomingData<Hit> incomingData = new DefaultIncomingData<>();
+        EventStream stream = new EventStream(id, incomingData);
+        incomingData.assignOwner(stream);
+        return stream;
+    }
+
+    public void add(String data) {
+        add(data, DEFAULT_EVENT_TYPE);
+    }
+
+    public void add(String data, String type) {
+        incoming().add(new Event(String.valueOf(eventCount + 1), data, type));
+        eventCount++;
+    }
+
+    public void error(String source, ErrorMessage message) {
+        incoming().add(new DefaultErrorHit(source, message));
+    }
+
+    public void markComplete() {
+        incoming().markComplete();
+    }
+
+    public static class Event extends Hit {
+
+        private final String type;
+
+        public Event(String id, String data, String type) {
+            super(id);
+            this.type = type;
+            setField(type, data);
+        }
+
+        public String toString() {
+            return getField(type).toString();
+        }
+
+        public String type() {
+            return type;
+        }
+
+    }
+}