Merge "Move RingBuffer from SF utils into libui" into main

Author: AMouri

…rvices/surfaceflinger/Utils/RingBuffer.h libs/ui/include/ui/RingBuffer.hservices/surfaceflinger/Utils/RingBuffer.h renamed to libs/ui/include/ui/RingBuffer.h services/surfaceflinger/Utils/RingBuffer.h renamed to libs/ui/include/ui/RingBuffer.h

@@ -19,7 +19,7 @@
 #include <stddef.h>
 #include <array>
 
-namespace android::utils {
+namespace android::ui {
 
 template <class T, size_t SIZE>
 class RingBuffer {
@@ -31,8 +31,8 @@ class RingBuffer {
     ~RingBuffer() = default;
 
     constexpr size_t capacity() const { return SIZE; }
-
     size_t size() const { return mCount; }
+    bool isFull() const { return size() == capacity(); }
 
     T& next() {
         mHead = static_cast<size_t>(mHead + 1) % SIZE;
@@ -67,4 +67,4 @@ class RingBuffer {
     size_t mCount = 0;
 };
 
-} // namespace android::utils
+} // namespace android::ui

libs/ui/tests/Android.bp

@@ -143,6 +143,17 @@ cc_test {
     ],
 }
 
+cc_test {
+    name: "RingBuffer_test",
+    test_suites: ["device-tests"],
+    shared_libs: ["libui"],
+    srcs: ["RingBuffer_test.cpp"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+}
+
 cc_test {
     name: "Size_test",
     test_suites: ["device-tests"],

libs/ui/tests/RingBuffer_test.cpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <gtest/gtest.h>
+#include <ui/RingBuffer.h>
+
+namespace android::ui {
+
+TEST(RingBuffer, basic) {
+    RingBuffer<int, 5> rb;
+
+    rb.next() = 1;
+    ASSERT_EQ(1, rb.size());
+    ASSERT_EQ(1, rb.back());
+    ASSERT_EQ(1, rb.front());
+
+    rb.next() = 2;
+    ASSERT_EQ(2, rb.size());
+    ASSERT_EQ(2, rb.back());
+    ASSERT_EQ(1, rb.front());
+    ASSERT_EQ(1, rb[-1]);
+
+    rb.next() = 3;
+    ASSERT_EQ(3, rb.size());
+    ASSERT_EQ(3, rb.back());
+    ASSERT_EQ(1, rb.front());
+    ASSERT_EQ(2, rb[-1]);
+    ASSERT_EQ(1, rb[-2]);
+
+    rb.next() = 4;
+    ASSERT_EQ(4, rb.size());
+    ASSERT_EQ(4, rb.back());
+    ASSERT_EQ(1, rb.front());
+    ASSERT_EQ(3, rb[-1]);
+    ASSERT_EQ(2, rb[-2]);
+    ASSERT_EQ(1, rb[-3]);
+
+    rb.next() = 5;
+    ASSERT_EQ(5, rb.size());
+    ASSERT_EQ(5, rb.back());
+    ASSERT_EQ(1, rb.front());
+    ASSERT_EQ(4, rb[-1]);
+    ASSERT_EQ(3, rb[-2]);
+    ASSERT_EQ(2, rb[-3]);
+    ASSERT_EQ(1, rb[-4]);
+
+    rb.next() = 6;
+    ASSERT_EQ(5, rb.size());
+    ASSERT_EQ(6, rb.back());
+    ASSERT_EQ(2, rb.front());
+    ASSERT_EQ(5, rb[-1]);
+    ASSERT_EQ(4, rb[-2]);
+    ASSERT_EQ(3, rb[-3]);
+    ASSERT_EQ(2, rb[-4]);
+}
+
+} // namespace android::ui

services/surfaceflinger/HdrLayerInfoReporter.h

@@ -19,11 +19,11 @@
 #include <android-base/thread_annotations.h>
 #include <android/gui/IHdrLayerInfoListener.h>
 #include <binder/IBinder.h>
+#include <ui/RingBuffer.h>
 #include <utils/Timers.h>
 
 #include <unordered_map>
 
-#include "Utils/RingBuffer.h"
 #include "WpHash.h"
 
 namespace android {
@@ -102,7 +102,7 @@ class HdrLayerInfoReporter final : public IBinder::DeathRecipient {
         EventHistoryEntry(const HdrLayerInfo& info) : info(info) { timestamp = systemTime(); }
     };
 
-    utils::RingBuffer<EventHistoryEntry, 32> mHdrInfoHistory;
+    ui::RingBuffer<EventHistoryEntry, 32> mHdrInfoHistory;
 };
 
 } // namespace android

services/surfaceflinger/PowerAdvisor/PowerAdvisor.cpp

@@ -515,7 +515,7 @@ void PowerAdvisor::setRequiresRenderEngine(DisplayId displayId, bool requiresRen
 }
 
 void PowerAdvisor::setExpectedPresentTime(TimePoint expectedPresentTime) {
-    mExpectedPresentTimes.append(expectedPresentTime);
+    mExpectedPresentTimes.next() = expectedPresentTime;
 }
 
 void PowerAdvisor::setSfPresentTiming(TimePoint presentFenceTime, TimePoint presentEndTime) {
@@ -532,7 +532,7 @@ void PowerAdvisor::setHwcPresentDelayedTime(DisplayId displayId, TimePoint earli
 }
 
 void PowerAdvisor::setCommitStart(TimePoint commitStartTime) {
-    mCommitStartTimes.append(commitStartTime);
+    mCommitStartTimes.next() = commitStartTime;
 }
 
 void PowerAdvisor::setCompositeEnd(TimePoint compositeEndTime) {
@@ -579,7 +579,7 @@ std::optional<hal::WorkDuration> PowerAdvisor::estimateWorkDuration() {
     }
 
     // Tracks when we finish presenting to hwc
-    TimePoint estimatedHwcEndTime = mCommitStartTimes[0];
+    TimePoint estimatedHwcEndTime = mCommitStartTimes.back();
 
     // How long we spent this frame not doing anything, waiting for fences or vsync
     Duration idleDuration = 0ns;
@@ -643,13 +643,13 @@ std::optional<hal::WorkDuration> PowerAdvisor::estimateWorkDuration() {
     // Also add the frame delay duration since the target did not move while we were delayed
     Duration totalDuration = mFrameDelayDuration +
             std::max(estimatedHwcEndTime, estimatedGpuEndTime.value_or(TimePoint{0ns})) -
-            mCommitStartTimes[0];
+            mCommitStartTimes.back();
     Duration totalDurationWithoutGpu =
-            mFrameDelayDuration + estimatedHwcEndTime - mCommitStartTimes[0];
+            mFrameDelayDuration + estimatedHwcEndTime - mCommitStartTimes.back();
 
     // We finish SurfaceFlinger when post-composition finishes, so add that in here
     Duration flingerDuration =
-            estimatedFlingerEndTime + mLastPostcompDuration - mCommitStartTimes[0];
+            estimatedFlingerEndTime + mLastPostcompDuration - mCommitStartTimes.back();
     Duration estimatedGpuDuration = firstGpuTimeline.has_value()
             ? estimatedGpuEndTime.value_or(TimePoint{0ns}) - firstGpuTimeline->startTime
             : Duration::fromNs(0);
@@ -661,7 +661,7 @@ std::optional<hal::WorkDuration> PowerAdvisor::estimateWorkDuration() {
     hal::WorkDuration duration{
             .timeStampNanos = TimePoint::now().ns(),
             .durationNanos = combinedDuration.ns(),
-            .workPeriodStartTimestampNanos = mCommitStartTimes[0].ns(),
+            .workPeriodStartTimestampNanos = mCommitStartTimes.back().ns(),
             .cpuDurationNanos = supportsGpuReporting() ? cpuDuration.ns() : 0,
             .gpuDurationNanos = supportsGpuReporting() ? estimatedGpuDuration.ns() : 0,
     };

services/surfaceflinger/PowerAdvisor/PowerAdvisor.h

@@ -23,6 +23,7 @@
 
 #include <ui/DisplayId.h>
 #include <ui/FenceTime.h>
+#include <ui/RingBuffer.h>
 #include <utils/Mutex.h>
 
 // FMQ library in IPower does questionable conversions
@@ -247,27 +248,6 @@ class PowerAdvisor final : public adpf::PowerAdvisor {
         std::optional<GpuTimeline> estimateGpuTiming(std::optional<TimePoint> previousEndTime);
     };
 
-    template <class T, size_t N>
-    class RingBuffer {
-        std::array<T, N> elements = {};
-        size_t mIndex = 0;
-        size_t numElements = 0;
-
-    public:
-        void append(T item) {
-            mIndex = (mIndex + 1) % N;
-            numElements = std::min(N, numElements + 1);
-            elements[mIndex] = item;
-        }
-        bool isFull() const { return numElements == N; }
-        // Allows access like [0] == current, [-1] = previous, etc..
-        T& operator[](int offset) {
-            size_t positiveOffset =
-                    static_cast<size_t>((offset % static_cast<int>(N)) + static_cast<int>(N));
-            return elements[(mIndex + positiveOffset) % N];
-        }
-    };
-
     // Filter and sort the display ids by a given property
     std::vector<DisplayId> getOrderedDisplayIds(
             std::optional<TimePoint> DisplayTimingData::*sortBy);
@@ -287,9 +267,9 @@ class PowerAdvisor final : public adpf::PowerAdvisor {
     // Last frame's post-composition duration
     Duration mLastPostcompDuration{0ns};
     // Buffer of recent commit start times
-    RingBuffer<TimePoint, 2> mCommitStartTimes;
+    ui::RingBuffer<TimePoint, 2> mCommitStartTimes;
     // Buffer of recent expected present times
-    RingBuffer<TimePoint, 2> mExpectedPresentTimes;
+    ui::RingBuffer<TimePoint, 2> mExpectedPresentTimes;
     // Most recent present fence time, provided by SF after composition engine finishes presenting
     TimePoint mLastPresentFenceTime;
     // Most recent composition engine present end time, returned with the present fence from SF

services/surfaceflinger/Scheduler/include/scheduler/FrameTargeter.h

@@ -24,6 +24,7 @@
 #include <ui/DisplayId.h>
 #include <ui/Fence.h>
 #include <ui/FenceTime.h>
+#include <ui/RingBuffer.h>
 
 #include <scheduler/Features.h>
 #include <scheduler/FrameTime.h>
@@ -34,7 +35,6 @@
 // TODO(b/185536303): Pull to FTL.
 #include "../../../TracedOrdinal.h"
 #include "../../../Utils/Dumper.h"
-#include "../../../Utils/RingBuffer.h"
 
 namespace android::scheduler {
 
@@ -108,7 +108,7 @@ class FrameTarget {
     std::pair<bool /* wouldBackpressure */, PresentFence> expectedSignaledPresentFence(
             Period vsyncPeriod, Period minFramePeriod) const;
     std::array<PresentFence, 2> mPresentFencesLegacy;
-    utils::RingBuffer<PresentFence, 5> mPresentFences;
+    ui::RingBuffer<PresentFence, 5> mPresentFences;
 
     FrameTime mLastSignaledFrameTime;