1 files changed, 123 insertions, 0 deletions
diff --git a/src/zen/trace/timeline_query.cpp b/src/zen/trace/timeline_query.cpp
new file mode 100644
index 000000000..d90c79a29
--- /dev/null
+++ b/src/zen/trace/timeline_query.cpp
@@ -0,0 +1,123 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include "timeline_query.h"
+
+#include <algorithm>
+
+namespace zen::trace_detail {
+
+namespace {
+
+	// Pick the LOD level a given resolution should read from. Mirrors the
+	// historical selection in trace_viewer_service.cpp: resolution 0 reads the
+	// raw LOD 0; otherwise the smallest LOD whose ResolutionUs >= the request
+	// wins, falling back to the coarsest level if none qualify.
+	//
+	// Returned values: 0 == raw scopes (LOD 0), 1..kTimelineLodCount == DetailLevels[lod-1].
+	size_t SelectLodIndex(uint32_t ResolutionUs)
+	{
+		if (ResolutionUs == 0)
+		{
+			return 0;
+		}
+		for (size_t I = 0; I < kTimelineLodCount; ++I)
+		{
+			if (kTimelineLodResolutions[I] >= ResolutionUs)
+			{
+				return I + 1;
+			}
+		}
+		return kTimelineLodCount;
+	}
+
+	const eastl::vector<TimelineScope>& LodScopes(const ThreadTimeline& Timeline, size_t LodIndex)
+	{
+		if (LodIndex == 0)
+		{
+			return Timeline.Scopes;
+		}
+		return Timeline.DetailLevels[LodIndex - 1].Scopes;
+	}
+
+	void ExtractScopesInto(const ThreadTimeline& Timeline, const TimelineQueryRequest& Req, std::vector<TimelineScopeView>& Out)
+	{
+		const eastl::vector<TimelineScope>& Scopes = LodScopes(Timeline, SelectLodIndex(Req.ResolutionUs));
+
+		auto MidIt =
+			std::lower_bound(Scopes.begin(), Scopes.end(), Req.StartUs, [](const TimelineScope& S, uint32_t V) { return S.BeginUs < V; });
+
+		for (auto It = Scopes.begin(); It != MidIt; ++It)
+		{
+			if ((It->BeginUs + It->DurationUs) < Req.StartUs || It->DurationUs < Req.MinDurUs)
+			{
+				continue;
+			}
+			Out.push_back({It->BeginUs, It->DurationUs, It->NameId, It->Depth, It->MergeCount});
+		}
+		for (auto It = MidIt; It != Scopes.end(); ++It)
+		{
+			if (It->BeginUs > Req.EndUs)
+			{
+				break;
+			}
+			if (It->DurationUs < Req.MinDurUs)
+			{
+				continue;
+			}
+			Out.push_back({It->BeginUs, It->DurationUs, It->NameId, It->Depth, It->MergeCount});
+		}
+	}
+
+	const ThreadTimeline* FindThread(const TraceModel& Model, uint32_t ThreadId)
+	{
+		auto It = std::find_if(Model.Timelines.begin(), Model.Timelines.end(), [ThreadId](const ThreadTimeline& T) {
+			return T.ThreadId == ThreadId;
+		});
+		return (It != Model.Timelines.end()) ? &*It : nullptr;
+	}
+
+	class InMemoryTimelineQuery final : public TimelineQuery
+	{
+	public:
+		explicit InMemoryTimelineQuery(const TraceModel& Model) : m_Model(Model) {}
+
+		void QueryThread(uint32_t ThreadId, const TimelineQueryRequest& Req, std::vector<TimelineScopeView>& Out) const override
+		{
+			const ThreadTimeline* Timeline = FindThread(m_Model, ThreadId);
+			if (Timeline)
+			{
+				ExtractScopesInto(*Timeline, Req, Out);
+			}
+		}
+
+		void QueryBatch(std::span<const uint32_t> ThreadIds, const TimelineQueryRequest& Req, BatchResult& Out) const override
+		{
+			Out.Scopes.clear();
+			Out.Ranges.clear();
+			Out.Ranges.reserve(ThreadIds.size());
+
+			for (uint32_t ThreadId : ThreadIds)
+			{
+				const uint32_t		  Begin	   = uint32_t(Out.Scopes.size());
+				const ThreadTimeline* Timeline = FindThread(m_Model, ThreadId);
+				if (Timeline)
+				{
+					ExtractScopesInto(*Timeline, Req, Out.Scopes);
+				}
+				Out.Ranges.push_back({Begin, uint32_t(Out.Scopes.size())});
+			}
+		}
+
+	private:
+		const TraceModel& m_Model;
+	};
+
+}  // namespace
+
+std::unique_ptr<TimelineQuery>
+MakeInMemoryTimelineQuery(const TraceModel& Model)
+{
+	return std::make_unique<InMemoryTimelineQuery>(Model);
+}
+
+}  // namespace zen::trace_detail