Merge "Skip window infos updates if no listeners" into udc-dev

7 files changed, 364 insertions, 119 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index b1d4b3c837..2ac1db961f 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2547,7 +2547,7 @@ bool SurfaceFlinger::commit(TimePoint frameTime, VsyncId vsyncId, TimePoint expe
     }
 
     updateCursorAsync();
-    updateInputFlinger(vsyncId);
+    updateInputFlinger(vsyncId, frameTime);
 
     if (mLayerTracingEnabled && !mLayerTracing.flagIsSet(LayerTracing::TRACE_COMPOSITION)) {
         // This will block and tracing should only be enabled for debugging.
@@ -3740,7 +3740,7 @@ void SurfaceFlinger::commitTransactionsLocked(uint32_t transactionFlags) {
     doCommitTransactions();
 }
 
-void SurfaceFlinger::updateInputFlinger(VsyncId vsyncId) {
+void SurfaceFlinger::updateInputFlinger(VsyncId vsyncId, TimePoint frameTime) {
     if (!mInputFlinger || (!mUpdateInputInfo && mInputWindowCommands.empty())) {
         return;
     }
@@ -3752,8 +3752,6 @@ void SurfaceFlinger::updateInputFlinger(VsyncId vsyncId) {
     if (mUpdateInputInfo) {
         mUpdateInputInfo = false;
         updateWindowInfo = true;
-        mLastInputFlingerUpdateVsyncId = vsyncId;
-        mLastInputFlingerUpdateTimestamp = systemTime();
         buildWindowInfos(windowInfos, displayInfos);
     }
 
@@ -3775,17 +3773,17 @@ void SurfaceFlinger::updateInputFlinger(VsyncId vsyncId) {
                                                       inputWindowCommands =
                                                               std::move(mInputWindowCommands),
                                                       inputFlinger = mInputFlinger, this,
-                                                      visibleWindowsChanged]() {
+                                                      visibleWindowsChanged, vsyncId, frameTime]() {
         ATRACE_NAME("BackgroundExecutor::updateInputFlinger");
         if (updateWindowInfo) {
             mWindowInfosListenerInvoker
-                    ->windowInfosChanged(std::move(windowInfos), std::move(displayInfos),
+                    ->windowInfosChanged(gui::WindowInfosUpdate{std::move(windowInfos),
+                                                                std::move(displayInfos),
+                                                                vsyncId.value, frameTime.ns()},
                                          std::move(
                                                  inputWindowCommands.windowInfosReportedListeners),
                                          /* forceImmediateCall= */ visibleWindowsChanged ||
-                                                 !inputWindowCommands.focusRequests.empty(),
-                                         mLastInputFlingerUpdateVsyncId,
-                                         mLastInputFlingerUpdateTimestamp);
+                                                 !inputWindowCommands.focusRequests.empty());
         } else {
             // If there are listeners but no changes to input windows, call the listeners
             // immediately.
@@ -6152,27 +6150,14 @@ void SurfaceFlinger::dumpAllLocked(const DumpArgs& args, const std::string& comp
     result.append("\n");
 
     result.append("Window Infos:\n");
-    StringAppendF(&result, "  input flinger update vsync id: %" PRId64 "\n",
-                  mLastInputFlingerUpdateVsyncId.value);
-    StringAppendF(&result, "  input flinger update timestamp (ns): %" PRId64 "\n",
-                  mLastInputFlingerUpdateTimestamp);
+    auto windowInfosDebug = mWindowInfosListenerInvoker->getDebugInfo();
+    StringAppendF(&result, "  max send vsync id: %" PRId64 "\n",
+                  windowInfosDebug.maxSendDelayVsyncId.value);
+    StringAppendF(&result, "  max send delay (ns): %" PRId64 " ns\n",
+                  windowInfosDebug.maxSendDelayDuration);
+    StringAppendF(&result, "  unsent messages: %" PRIu32 "\n",
+                  windowInfosDebug.pendingMessageCount);
     result.append("\n");
-
-    if (int64_t unsentVsyncId = mWindowInfosListenerInvoker->getUnsentMessageVsyncId().value;
-        unsentVsyncId != -1) {
-        StringAppendF(&result, "  unsent input flinger update vsync id: %" PRId64 "\n",
-                      unsentVsyncId);
-        StringAppendF(&result, "  unsent input flinger update timestamp (ns): %" PRId64 "\n",
-                      mWindowInfosListenerInvoker->getUnsentMessageTimestamp());
-        result.append("\n");
-    }
-
-    if (uint32_t pendingMessages = mWindowInfosListenerInvoker->getPendingMessageCount();
-        pendingMessages != 0) {
-        StringAppendF(&result, "  pending input flinger calls: %" PRIu32 "\n",
-                      mWindowInfosListenerInvoker->getPendingMessageCount());
-        result.append("\n");
-    }
 }
 
 mat4 SurfaceFlinger::calculateColorMatrix(float saturation) {
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index e2691ab39a..0bc506f1fe 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -722,7 +722,7 @@ private:
     void updateLayerHistory(const frontend::LayerSnapshot& snapshot);
     frontend::Update flushLifecycleUpdates() REQUIRES(kMainThreadContext);
 
-    void updateInputFlinger(VsyncId);
+    void updateInputFlinger(VsyncId vsyncId, TimePoint frameTime);
     void persistDisplayBrightness(bool needsComposite) REQUIRES(kMainThreadContext);
     void buildWindowInfos(std::vector<gui::WindowInfo>& outWindowInfos,
                           std::vector<gui::DisplayInfo>& outDisplayInfos);
@@ -1259,9 +1259,6 @@ private:
 
     VsyncId mLastCommittedVsyncId;
 
-    VsyncId mLastInputFlingerUpdateVsyncId;
-    nsecs_t mLastInputFlingerUpdateTimestamp;
-
     // If blurs should be enabled on this device.
     bool mSupportsBlur = false;
     std::atomic<uint32_t> mFrameMissedCount = 0;
diff --git a/services/surfaceflinger/WindowInfosListenerInvoker.cpp b/services/surfaceflinger/WindowInfosListenerInvoker.cpp
index 2b62638c61..20699ef123 100644
--- a/services/surfaceflinger/WindowInfosListenerInvoker.cpp
+++ b/services/surfaceflinger/WindowInfosListenerInvoker.cpp
@@ -16,8 +16,11 @@
 
 #include <ftl/small_vector.h>
 #include <gui/ISurfaceComposer.h>
+#include <gui/TraceUtils.h>
 #include <gui/WindowInfosUpdate.h>
+#include <scheduler/Time.h>
 
+#include "BackgroundExecutor.h"
 #include "WindowInfosListenerInvoker.h"
 
 namespace android {
@@ -26,7 +29,7 @@ using gui::DisplayInfo;
 using gui::IWindowInfosListener;
 using gui::WindowInfo;
 
-using WindowInfosListenerVector = ftl::SmallVector<const sp<IWindowInfosListener>, 3>;
+using WindowInfosListenerVector = ftl::SmallVector<const sp<gui::IWindowInfosListener>, 3>;
 
 struct WindowInfosReportedListenerInvoker : gui::BnWindowInfosReportedListener,
                                             IBinder::DeathRecipient {
@@ -86,45 +89,19 @@ void WindowInfosListenerInvoker::binderDied(const wp<IBinder>& who) {
 }
 
 void WindowInfosListenerInvoker::windowInfosChanged(
-        std::vector<WindowInfo> windowInfos, std::vector<DisplayInfo> displayInfos,
-        WindowInfosReportedListenerSet reportedListeners, bool forceImmediateCall, VsyncId vsyncId,
-        nsecs_t timestamp) {
-    reportedListeners.insert(sp<WindowInfosListenerInvoker>::fromExisting(this));
-    auto callListeners = [this, windowInfos = std::move(windowInfos),
-                          displayInfos = std::move(displayInfos), vsyncId,
-                          timestamp](WindowInfosReportedListenerSet reportedListeners) mutable {
-        WindowInfosListenerVector windowInfosListeners;
-        {
-            std::scoped_lock lock(mListenersMutex);
-            for (const auto& [_, listener] : mWindowInfosListeners) {
-                windowInfosListeners.push_back(listener);
-            }
-        }
-
-        auto reportedInvoker =
-                sp<WindowInfosReportedListenerInvoker>::make(windowInfosListeners,
-                                                             std::move(reportedListeners));
-
-        gui::WindowInfosUpdate update(std::move(windowInfos), std::move(displayInfos),
-                                      vsyncId.value, timestamp);
-
-        for (const auto& listener : windowInfosListeners) {
-            sp<IBinder> asBinder = IInterface::asBinder(listener);
-
-            // linkToDeath is used here to ensure that the windowInfosReportedListeners
-            // are called even if one of the windowInfosListeners dies before
-            // calling onWindowInfosReported.
-            asBinder->linkToDeath(reportedInvoker);
+        gui::WindowInfosUpdate update, WindowInfosReportedListenerSet reportedListeners,
+        bool forceImmediateCall) {
+    WindowInfosListenerVector listeners;
+    {
+        std::scoped_lock lock{mMessagesMutex};
 
-            auto status = listener->onWindowInfosChanged(update, reportedInvoker);
-            if (!status.isOk()) {
-                reportedInvoker->onWindowInfosReported();
-            }
+        if (!mDelayInfo) {
+            mDelayInfo = DelayInfo{
+                    .vsyncId = update.vsyncId,
+                    .frameTime = update.timestamp,
+            };
         }
-    };
 
-    {
-        std::scoped_lock lock(mMessagesMutex);
         // If there are unacked messages and this isn't a forced call, then return immediately.
         // If a forced window infos change doesn't happen first, the update will be sent after
         // the WindowInfosReportedListeners are called. If a forced window infos change happens or
@@ -132,44 +109,87 @@ void WindowInfosListenerInvoker::windowInfosChanged(
         // will be dropped and the listeners will only be called with the latest info. This is done
         // to reduce the amount of binder memory used.
         if (mActiveMessageCount > 0 && !forceImmediateCall) {
-            mWindowInfosChangedDelayed = std::move(callListeners);
-            mUnsentVsyncId = vsyncId;
-            mUnsentTimestamp = timestamp;
-            mReportedListenersDelayed.merge(reportedListeners);
+            mDelayedUpdate = std::move(update);
+            mReportedListeners.merge(reportedListeners);
+            return;
+        }
+
+        if (mDelayedUpdate) {
+            mDelayedUpdate.reset();
+        }
+
+        {
+            std::scoped_lock lock{mListenersMutex};
+            for (const auto& [_, listener] : mWindowInfosListeners) {
+                listeners.push_back(listener);
+            }
+        }
+        if (CC_UNLIKELY(listeners.empty())) {
+            mReportedListeners.merge(reportedListeners);
+            mDelayInfo.reset();
             return;
         }
 
-        mWindowInfosChangedDelayed = nullptr;
-        mUnsentVsyncId = {-1};
-        mUnsentTimestamp = -1;
-        reportedListeners.merge(mReportedListenersDelayed);
+        reportedListeners.insert(sp<WindowInfosListenerInvoker>::fromExisting(this));
+        reportedListeners.merge(mReportedListeners);
+        mReportedListeners.clear();
+
         mActiveMessageCount++;
+        updateMaxSendDelay();
+        mDelayInfo.reset();
     }
-    callListeners(std::move(reportedListeners));
-}
 
-binder::Status WindowInfosListenerInvoker::onWindowInfosReported() {
-    std::function<void(WindowInfosReportedListenerSet)> callListeners;
-    WindowInfosReportedListenerSet reportedListeners;
+    auto reportedInvoker =
+            sp<WindowInfosReportedListenerInvoker>::make(listeners, std::move(reportedListeners));
 
-    {
-        std::scoped_lock lock{mMessagesMutex};
-        mActiveMessageCount--;
-        if (!mWindowInfosChangedDelayed || mActiveMessageCount > 0) {
-            return binder::Status::ok();
-        }
+    for (const auto& listener : listeners) {
+        sp<IBinder> asBinder = IInterface::asBinder(listener);
 
-        mActiveMessageCount++;
-        callListeners = std::move(mWindowInfosChangedDelayed);
-        mWindowInfosChangedDelayed = nullptr;
-        mUnsentVsyncId = {-1};
-        mUnsentTimestamp = -1;
-        reportedListeners = std::move(mReportedListenersDelayed);
-        mReportedListenersDelayed.clear();
+        // linkToDeath is used here to ensure that the windowInfosReportedListeners
+        // are called even if one of the windowInfosListeners dies before
+        // calling onWindowInfosReported.
+        asBinder->linkToDeath(reportedInvoker);
+
+        auto status = listener->onWindowInfosChanged(update, reportedInvoker);
+        if (!status.isOk()) {
+            reportedInvoker->onWindowInfosReported();
+        }
     }
+}
 
-    callListeners(std::move(reportedListeners));
+binder::Status WindowInfosListenerInvoker::onWindowInfosReported() {
+    BackgroundExecutor::getInstance().sendCallbacks({[this]() {
+        gui::WindowInfosUpdate update;
+        {
+            std::scoped_lock lock{mMessagesMutex};
+            mActiveMessageCount--;
+            if (!mDelayedUpdate || mActiveMessageCount > 0) {
+                return;
+            }
+            update = std::move(*mDelayedUpdate);
+            mDelayedUpdate.reset();
+        }
+        windowInfosChanged(std::move(update), {}, false);
+    }});
     return binder::Status::ok();
 }
 
+WindowInfosListenerInvoker::DebugInfo WindowInfosListenerInvoker::getDebugInfo() {
+    std::scoped_lock lock{mMessagesMutex};
+    updateMaxSendDelay();
+    mDebugInfo.pendingMessageCount = mActiveMessageCount;
+    return mDebugInfo;
+}
+
+void WindowInfosListenerInvoker::updateMaxSendDelay() {
+    if (!mDelayInfo) {
+        return;
+    }
+    nsecs_t delay = TimePoint::now().ns() - mDelayInfo->frameTime;
+    if (delay > mDebugInfo.maxSendDelayDuration) {
+        mDebugInfo.maxSendDelayDuration = delay;
+        mDebugInfo.maxSendDelayVsyncId = VsyncId{mDelayInfo->vsyncId};
+    }
+}
+
 } // namespace android
diff --git a/services/surfaceflinger/WindowInfosListenerInvoker.h b/services/surfaceflinger/WindowInfosListenerInvoker.h
index e35d0564b5..bc465a3a2b 100644
--- a/services/surfaceflinger/WindowInfosListenerInvoker.h
+++ b/services/surfaceflinger/WindowInfosListenerInvoker.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <optional>
 #include <unordered_set>
 
 #include <android/gui/BnWindowInfosReportedListener.h>
@@ -40,26 +41,18 @@ public:
     void addWindowInfosListener(sp<gui::IWindowInfosListener>);
     void removeWindowInfosListener(const sp<gui::IWindowInfosListener>& windowInfosListener);
 
-    void windowInfosChanged(std::vector<gui::WindowInfo>, std::vector<gui::DisplayInfo>,
+    void windowInfosChanged(gui::WindowInfosUpdate update,
                             WindowInfosReportedListenerSet windowInfosReportedListeners,
-                            bool forceImmediateCall, VsyncId vsyncId, nsecs_t timestamp);
+                            bool forceImmediateCall);
 
     binder::Status onWindowInfosReported() override;
 
-    VsyncId getUnsentMessageVsyncId() {
-        std::scoped_lock lock(mMessagesMutex);
-        return mUnsentVsyncId;
-    }
-
-    nsecs_t getUnsentMessageTimestamp() {
-        std::scoped_lock lock(mMessagesMutex);
-        return mUnsentTimestamp;
-    }
-
-    uint32_t getPendingMessageCount() {
-        std::scoped_lock lock(mMessagesMutex);
-        return mActiveMessageCount;
-    }
+    struct DebugInfo {
+        VsyncId maxSendDelayVsyncId;
+        nsecs_t maxSendDelayDuration;
+        uint32_t pendingMessageCount;
+    };
+    DebugInfo getDebugInfo();
 
 protected:
     void binderDied(const wp<IBinder>& who) override;
@@ -73,11 +66,16 @@ private:
 
     std::mutex mMessagesMutex;
     uint32_t mActiveMessageCount GUARDED_BY(mMessagesMutex) = 0;
-    std::function<void(WindowInfosReportedListenerSet)> mWindowInfosChangedDelayed
-            GUARDED_BY(mMessagesMutex);
-    VsyncId mUnsentVsyncId GUARDED_BY(mMessagesMutex) = {-1};
-    nsecs_t mUnsentTimestamp GUARDED_BY(mMessagesMutex) = -1;
-    WindowInfosReportedListenerSet mReportedListenersDelayed;
+    std::optional<gui::WindowInfosUpdate> mDelayedUpdate GUARDED_BY(mMessagesMutex);
+    WindowInfosReportedListenerSet mReportedListeners;
+
+    DebugInfo mDebugInfo GUARDED_BY(mMessagesMutex);
+    struct DelayInfo {
+        int64_t vsyncId;
+        nsecs_t frameTime;
+    };
+    std::optional<DelayInfo> mDelayInfo GUARDED_BY(mMessagesMutex);
+    void updateMaxSendDelay() REQUIRES(mMessagesMutex);
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h b/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
index da5ec480cc..4d03be04b3 100644
--- a/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
+++ b/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
@@ -590,7 +590,7 @@ public:
         mFlinger->binderDied(display);
         mFlinger->onFirstRef();
 
-        mFlinger->updateInputFlinger(VsyncId{0});
+        mFlinger->updateInputFlinger(VsyncId{}, TimePoint{});
         mFlinger->updateCursorAsync();
 
         mutableScheduler().setVsyncConfig({.sfOffset = mFdp.ConsumeIntegral<nsecs_t>(),
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 881b362f1e..db81bad968 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -139,6 +139,7 @@ cc_test {
         "VSyncReactorTest.cpp",
         "VsyncConfigurationTest.cpp",
         "VsyncScheduleTest.cpp",
+        "WindowInfosListenerInvokerTest.cpp",
     ],
 }
 
diff --git a/services/surfaceflinger/tests/unittests/WindowInfosListenerInvokerTest.cpp b/services/surfaceflinger/tests/unittests/WindowInfosListenerInvokerTest.cpp
new file mode 100644
index 0000000000..af4971b063
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/WindowInfosListenerInvokerTest.cpp
@@ -0,0 +1,244 @@
+#include <android/gui/BnWindowInfosListener.h>
+#include <gtest/gtest.h>
+#include <gui/SurfaceComposerClient.h>
+#include <gui/WindowInfosUpdate.h>
+#include <condition_variable>
+
+#include "BackgroundExecutor.h"
+#include "WindowInfosListenerInvoker.h"
+#include "android/gui/IWindowInfosReportedListener.h"
+
+namespace android {
+
+class WindowInfosListenerInvokerTest : public testing::Test {
+protected:
+    WindowInfosListenerInvokerTest() : mInvoker(sp<WindowInfosListenerInvoker>::make()) {}
+
+    ~WindowInfosListenerInvokerTest() {
+        std::mutex mutex;
+        std::condition_variable cv;
+        bool flushComplete = false;
+        // Flush the BackgroundExecutor thread to ensure any scheduled tasks are complete.
+        // Otherwise, references those tasks hold may go out of scope before they are done
+        // executing.
+        BackgroundExecutor::getInstance().sendCallbacks({[&]() {
+            std::scoped_lock lock{mutex};
+            flushComplete = true;
+            cv.notify_one();
+        }});
+        std::unique_lock<std::mutex> lock{mutex};
+        cv.wait(lock, [&]() { return flushComplete; });
+    }
+
+    sp<WindowInfosListenerInvoker> mInvoker;
+};
+
+using WindowInfosUpdateConsumer = std::function<void(const gui::WindowInfosUpdate&,
+                                                     const sp<gui::IWindowInfosReportedListener>&)>;
+
+class Listener : public gui::BnWindowInfosListener {
+public:
+    Listener(WindowInfosUpdateConsumer consumer) : mConsumer(std::move(consumer)) {}
+
+    binder::Status onWindowInfosChanged(
+            const gui::WindowInfosUpdate& update,
+            const sp<gui::IWindowInfosReportedListener>& reportedListener) override {
+        mConsumer(update, reportedListener);
+        return binder::Status::ok();
+    }
+
+private:
+    WindowInfosUpdateConsumer mConsumer;
+};
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged calls a single window infos listener.
+TEST_F(WindowInfosListenerInvokerTest, callsSingleListener) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int callCount = 0;
+
+    mInvoker->addWindowInfosListener(
+            sp<Listener>::make([&](const gui::WindowInfosUpdate&,
+                                   const sp<gui::IWindowInfosReportedListener>& reportedListener) {
+                std::scoped_lock lock{mutex};
+                callCount++;
+                cv.notify_one();
+
+                reportedListener->onWindowInfosReported();
+            }));
+
+    BackgroundExecutor::getInstance().sendCallbacks(
+            {[this]() { mInvoker->windowInfosChanged({}, {}, false); }});
+
+    std::unique_lock<std::mutex> lock{mutex};
+    cv.wait(lock, [&]() { return callCount == 1; });
+    EXPECT_EQ(callCount, 1);
+}
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged calls multiple window infos listeners.
+TEST_F(WindowInfosListenerInvokerTest, callsMultipleListeners) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int callCount = 0;
+    const int expectedCallCount = 3;
+
+    for (int i = 0; i < expectedCallCount; i++) {
+        mInvoker->addWindowInfosListener(sp<Listener>::make(
+                [&](const gui::WindowInfosUpdate&,
+                    const sp<gui::IWindowInfosReportedListener>& reportedListener) {
+                    std::scoped_lock lock{mutex};
+                    callCount++;
+                    if (callCount == expectedCallCount) {
+                        cv.notify_one();
+                    }
+
+                    reportedListener->onWindowInfosReported();
+                }));
+    }
+
+    BackgroundExecutor::getInstance().sendCallbacks(
+            {[&]() { mInvoker->windowInfosChanged({}, {}, false); }});
+
+    std::unique_lock<std::mutex> lock{mutex};
+    cv.wait(lock, [&]() { return callCount == expectedCallCount; });
+    EXPECT_EQ(callCount, expectedCallCount);
+}
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged delays sending a second message until
+// after the WindowInfosReportedListener is called.
+TEST_F(WindowInfosListenerInvokerTest, delaysUnackedCall) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int callCount = 0;
+
+    // Simulate a slow ack by not calling the WindowInfosReportedListener.
+    mInvoker->addWindowInfosListener(sp<Listener>::make(
+            [&](const gui::WindowInfosUpdate&, const sp<gui::IWindowInfosReportedListener>&) {
+                std::scoped_lock lock{mutex};
+                callCount++;
+                cv.notify_one();
+            }));
+
+    BackgroundExecutor::getInstance().sendCallbacks({[&]() {
+        mInvoker->windowInfosChanged({}, {}, false);
+        mInvoker->windowInfosChanged({}, {}, false);
+    }});
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return callCount == 1; });
+    }
+    EXPECT_EQ(callCount, 1);
+
+    // Ack the first message.
+    mInvoker->onWindowInfosReported();
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return callCount == 2; });
+    }
+    EXPECT_EQ(callCount, 2);
+}
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged immediately sends a second message when
+// forceImmediateCall is true.
+TEST_F(WindowInfosListenerInvokerTest, sendsForcedMessage) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int callCount = 0;
+    const int expectedCallCount = 2;
+
+    // Simulate a slow ack by not calling the WindowInfosReportedListener.
+    mInvoker->addWindowInfosListener(sp<Listener>::make(
+            [&](const gui::WindowInfosUpdate&, const sp<gui::IWindowInfosReportedListener>&) {
+                std::scoped_lock lock{mutex};
+                callCount++;
+                if (callCount == expectedCallCount) {
+                    cv.notify_one();
+                }
+            }));
+
+    BackgroundExecutor::getInstance().sendCallbacks({[&]() {
+        mInvoker->windowInfosChanged({}, {}, false);
+        mInvoker->windowInfosChanged({}, {}, true);
+    }});
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return callCount == expectedCallCount; });
+    }
+    EXPECT_EQ(callCount, expectedCallCount);
+}
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged skips old messages when more than one
+// message is delayed.
+TEST_F(WindowInfosListenerInvokerTest, skipsDelayedMessage) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int64_t lastUpdateId = -1;
+
+    // Simulate a slow ack by not calling the WindowInfosReportedListener.
+    mInvoker->addWindowInfosListener(
+            sp<Listener>::make([&](const gui::WindowInfosUpdate& update,
+                                   const sp<gui::IWindowInfosReportedListener>&) {
+                std::scoped_lock lock{mutex};
+                lastUpdateId = update.vsyncId;
+                cv.notify_one();
+            }));
+
+    BackgroundExecutor::getInstance().sendCallbacks({[&]() {
+        mInvoker->windowInfosChanged({{}, {}, /* vsyncId= */ 1, 0}, {}, false);
+        mInvoker->windowInfosChanged({{}, {}, /* vsyncId= */ 2, 0}, {}, false);
+        mInvoker->windowInfosChanged({{}, {}, /* vsyncId= */ 3, 0}, {}, false);
+    }});
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return lastUpdateId == 1; });
+    }
+    EXPECT_EQ(lastUpdateId, 1);
+
+    // Ack the first message. The third update should be sent.
+    mInvoker->onWindowInfosReported();
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return lastUpdateId == 3; });
+    }
+    EXPECT_EQ(lastUpdateId, 3);
+}
+
+// Test that WindowInfosListenerInvoker#windowInfosChanged immediately calls listener after a call
+// where no listeners were configured.
+TEST_F(WindowInfosListenerInvokerTest, noListeners) {
+    std::mutex mutex;
+    std::condition_variable cv;
+
+    int callCount = 0;
+
+    // Test that calling windowInfosChanged without any listeners doesn't cause the next call to be
+    // delayed.
+    BackgroundExecutor::getInstance().sendCallbacks({[&]() {
+        mInvoker->windowInfosChanged({}, {}, false);
+        mInvoker->addWindowInfosListener(sp<Listener>::make(
+                [&](const gui::WindowInfosUpdate&, const sp<gui::IWindowInfosReportedListener>&) {
+                    std::scoped_lock lock{mutex};
+                    callCount++;
+                    cv.notify_one();
+                }));
+        mInvoker->windowInfosChanged({}, {}, false);
+    }});
+
+    {
+        std::unique_lock lock{mutex};
+        cv.wait(lock, [&]() { return callCount == 1; });
+    }
+    EXPECT_EQ(callCount, 1);
+}
+
+} // namespace android