Support emitting array in dynamic event

Author: cshung

src/coreclr/gc/gc.cpp

@@ -22279,6 +22279,27 @@ size_t gc_heap::exponential_smoothing (int gen, size_t collection_count, size_t
 //internal part of gc used by the serial and concurrent version
 void gc_heap::gc1()
 {
+#ifdef FEATURE_EVENT_TRACE
+    EventArray<uint8_t> arr1;
+    arr1.Count = 10;
+    arr1.Data = new (nothrow) uint8_t[10];
+    for (uint8_t i = 0; i < 10; i++)
+    {
+        arr1.Data[i] = i * i + i + 1;
+    }
+
+    EventArray<uint16_t> arr2;
+    arr2.Count = 6;
+    arr2.Data = new (nothrow) uint16_t[6];
+    for (uint16_t i = 0; i < 6; i++)
+    {
+        arr2.Data[i] = i * (i + 1);
+    }
+
+    GCEventFireTestArray_V1 (arr1, arr2);
+    delete[] arr1.Data;
+    delete[] arr2.Data;
+#endif //FEATURE_EVENT_TRACE
 #ifdef BACKGROUND_GC
     assert (settings.concurrent == (uint32_t)(bgc_thread_id.IsCurrentThread()));
 #endif //BACKGROUND_GC

src/coreclr/gc/gcevent_serializers.h

@@ -48,9 +48,16 @@
 #define ByteSwap64 __builtin_bswap64
 #endif // MSC_VER
 
-namespace gc_event
+template<class T>
+class EventArray
 {
+public:
+    uint8_t Count;
+    T* Data;
+};
 
+namespace gc_event
+{
 /*
  * `EventSerializatonTraits` is a trait implemented by types that
  * can be serialized to the payload of a dynamic event.
@@ -170,6 +177,45 @@ struct EventSerializationTraits<float>
     }
 };
 
+template<class T>
+struct EventSerializationTraits<EventArray<T>>
+{
+    static void Serialize(const EventArray<T>& value, uint8_t** pBuffer)
+    {
+        uint8_t* buffer = *pBuffer;
+        buffer[0] = value.Count;
+        buffer += 1;
+        for (uint8_t i = 0; i < value.Count; i++)
+        {
+            EventSerializationTraits<T>::Serialize(value.Data[i], &buffer);
+        }
+        *pBuffer = buffer;
+    }
+
+    static size_t SerializedSize(const EventArray<T>& value)
+    {
+        if (value.Count == 0)
+        {
+            return sizeof(uint8_t);
+        }
+        else
+        {
+            size_t elementSize = EventSerializationTraits<T>::SerializedSize(value.Data[0]);
+#ifdef DEBUG
+            //
+            // To support fast deserialization, we explicitly do not support arrays with 
+            // unequal element size.
+            //
+            for (int i = 1; i < value.Count; i++)
+            {
+                assert (elementSize == EventSerializationTraits<T>::SerializedSize(value.Data[i]));
+            }
+#endif //DEBUG
+            return sizeof(uint8_t) + elementSize * value.Count;
+        }
+    }
+};
+
 /*
  * Helper routines for serializing lists of arguments.
  */

src/coreclr/gc/gcevents.h

@@ -52,6 +52,7 @@ DYNAMIC_EVENT(CommittedUsage, GCEventLevel_Information, GCEventKeyword_GC, 1)
 DYNAMIC_EVENT(SizeAdaptationTuning, GCEventLevel_Information, GCEventKeyword_GC, 1)
 DYNAMIC_EVENT(SizeAdaptationFullGCTuning, GCEventLevel_Information, GCEventKeyword_GC, 1)
 DYNAMIC_EVENT(SizeAdaptationSample, GCEventLevel_Information, GCEventKeyword_GC, 1)
+DYNAMIC_EVENT(TestArray, GCEventLevel_Information, GCEventKeyword_GC, 1)
 
 #undef KNOWN_EVENT
 #undef DYNAMIC_EVENT