[Offload] OL_QUEUE_INFO_EMPTY (#152473)

Add a queue query that (if possible) reports whether the queue is empty

Author: RossBrunton

offload/liboffload/API/Queue.td

@@ -65,7 +65,8 @@ def : Enum {
   let desc = "Supported queue info.";
   let is_typed = 1;
   let etors = [
-    TaggedEtor<"DEVICE", "ol_device_handle_t", "The handle of the device associated with the queue.">
+    TaggedEtor<"DEVICE", "ol_device_handle_t", "The handle of the device associated with the queue.">,
+    TaggedEtor<"EMPTY", "bool", "True if the queue is known to be empty. May be unconditionally false if the device does not support status queries.">,
   ];
 }
 

offload/liboffload/src/OffloadImpl.cpp

@@ -530,6 +530,12 @@ Error olGetQueueInfoImplDetail(ol_queue_handle_t Queue,
   switch (PropName) {
   case OL_QUEUE_INFO_DEVICE:
     return Info.write<ol_device_handle_t>(Queue->Device);
+  case OL_QUEUE_INFO_EMPTY: {
+    auto Pending = Queue->Device->Device->hasPendingWork(Queue->AsyncInfo);
+    if (auto Err = Pending.takeError())
+      return Err;
+    return Info.write<bool>(!*Pending);
+  }
   default:
     return createOffloadError(ErrorCode::INVALID_ENUMERATION,
                               "olGetQueueInfo enum '%i' is invalid", PropName);

offload/unittests/OffloadAPI/queue/olGetQueueInfo.cpp

@@ -20,6 +20,12 @@ TEST_P(olGetQueueInfoTest, SuccessDevice) {
   ASSERT_EQ(Device, RetrievedDevice);
 }
 
+TEST_P(olGetQueueInfoTest, SuccessEmpty) {
+  bool Empty;
+  ASSERT_SUCCESS(
+      olGetQueueInfo(Queue, OL_QUEUE_INFO_EMPTY, sizeof(Empty), &Empty));
+}
+
 TEST_P(olGetQueueInfoTest, InvalidNullHandle) {
   ol_device_handle_t RetrievedDevice;
   ASSERT_ERROR(OL_ERRC_INVALID_NULL_HANDLE,

offload/unittests/OffloadAPI/queue/olGetQueueInfoSize.cpp

@@ -19,6 +19,12 @@ TEST_P(olGetQueueInfoSizeTest, SuccessDevice) {
   ASSERT_EQ(Size, sizeof(ol_device_handle_t));
 }
 
+TEST_P(olGetQueueInfoSizeTest, SuccessEmpty) {
+  size_t Size = 0;
+  ASSERT_SUCCESS(olGetQueueInfoSize(Queue, OL_QUEUE_INFO_EMPTY, &Size));
+  ASSERT_EQ(Size, sizeof(bool));
+}
+
 TEST_P(olGetQueueInfoSizeTest, InvalidNullHandle) {
   size_t Size = 0;
   ASSERT_ERROR(OL_ERRC_INVALID_NULL_HANDLE,