SF: Introduce DisplayModeController

DisplayModeController will centralize the logic and state for selecting
the DisplayMode of each physical display. For now, register a display's
DisplaySnapshot with DMC during configure, and move the creation of its
RefreshRateSelector to DMC::registerDisplay.

Bug: 241285876
Test: presubmit
Change-Id: I673914328bea64636b8bcd193e710131926334a5
diff --git a/services/surfaceflinger/Display/DisplayModeController.cpp b/services/surfaceflinger/Display/DisplayModeController.cpp
new file mode 100644
index 0000000..f093384
--- /dev/null
+++ b/services/surfaceflinger/Display/DisplayModeController.cpp
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024 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.
+ */
+
+#undef LOG_TAG
+#define LOG_TAG "DisplayModeController"
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+
+#include "Display/DisplayModeController.h"
+#include "Display/DisplaySnapshot.h"
+
+#include <log/log.h>
+
+namespace android::display {
+
+void DisplayModeController::registerDisplay(DisplaySnapshotRef snapshotRef,
+                                            DisplayModeId activeModeId,
+                                            scheduler::RefreshRateSelector::Config config) {
+    const auto& snapshot = snapshotRef.get();
+    const auto displayId = snapshot.displayId();
+
+    mDisplays.emplace_or_replace(displayId, snapshotRef, snapshot.displayModes(), activeModeId,
+                                 config);
+}
+
+void DisplayModeController::unregisterDisplay(PhysicalDisplayId displayId) {
+    const bool ok = mDisplays.erase(displayId);
+    ALOGE_IF(!ok, "%s: Unknown display %s", __func__, to_string(displayId).c_str());
+}
+
+auto DisplayModeController::selectorPtrFor(PhysicalDisplayId displayId) -> RefreshRateSelectorPtr {
+    return mDisplays.get(displayId)
+            .transform([](const Display& display) { return display.selectorPtr; })
+            .value_or(nullptr);
+}
+
+} // namespace android::display
diff --git a/services/surfaceflinger/Display/DisplayModeController.h b/services/surfaceflinger/Display/DisplayModeController.h
new file mode 100644
index 0000000..b6a6bee
--- /dev/null
+++ b/services/surfaceflinger/Display/DisplayModeController.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2024 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.
+ */
+
+#pragma once
+
+#include <memory>
+#include <utility>
+
+#include <android-base/thread_annotations.h>
+#include <ui/DisplayId.h>
+#include <ui/DisplayMap.h>
+
+#include "Display/DisplaySnapshotRef.h"
+#include "DisplayHardware/DisplayMode.h"
+#include "Scheduler/RefreshRateSelector.h"
+#include "ThreadContext.h"
+
+namespace android::display {
+
+// Selects the DisplayMode of each physical display, in accordance with DisplayManager policy and
+// certain heuristic signals.
+class DisplayModeController {
+public:
+    // The referenced DisplaySnapshot must outlive the registration.
+    void registerDisplay(DisplaySnapshotRef, DisplayModeId, scheduler::RefreshRateSelector::Config)
+            REQUIRES(kMainThreadContext);
+    void unregisterDisplay(PhysicalDisplayId) REQUIRES(kMainThreadContext);
+
+    // TODO(b/241285876): Remove once ownership is no longer shared with DisplayDevice.
+    using RefreshRateSelectorPtr = std::shared_ptr<scheduler::RefreshRateSelector>;
+
+    // Returns `nullptr` if the display is no longer registered (or never was).
+    RefreshRateSelectorPtr selectorPtrFor(PhysicalDisplayId) REQUIRES(kMainThreadContext);
+
+    // Used by tests to inject an existing RefreshRateSelector.
+    // TODO(b/241285876): Remove this.
+    void registerDisplay(PhysicalDisplayId displayId, DisplaySnapshotRef snapshotRef,
+                         RefreshRateSelectorPtr selectorPtr) {
+        mDisplays.emplace_or_replace(displayId, snapshotRef, selectorPtr);
+    }
+
+private:
+    struct Display {
+        Display(DisplaySnapshotRef snapshot, RefreshRateSelectorPtr selectorPtr)
+              : snapshot(snapshot), selectorPtr(std::move(selectorPtr)) {}
+
+        Display(DisplaySnapshotRef snapshot, DisplayModes modes, DisplayModeId activeModeId,
+                scheduler::RefreshRateSelector::Config config)
+              : Display(snapshot,
+                        std::make_shared<scheduler::RefreshRateSelector>(std::move(modes),
+                                                                         activeModeId, config)) {}
+
+        const DisplaySnapshotRef snapshot;
+        const RefreshRateSelectorPtr selectorPtr;
+    };
+
+    ui::PhysicalDisplayMap<PhysicalDisplayId, Display> mDisplays;
+};
+
+} // namespace android::display
diff --git a/services/surfaceflinger/Display/DisplaySnapshotRef.h b/services/surfaceflinger/Display/DisplaySnapshotRef.h
new file mode 100644
index 0000000..6cc5f7e
--- /dev/null
+++ b/services/surfaceflinger/Display/DisplaySnapshotRef.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2022 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.
+ */
+
+#pragma once
+
+#include <functional>
+
+namespace android::display {
+
+class DisplaySnapshot;
+
+using DisplaySnapshotRef = std::reference_wrapper<const DisplaySnapshot>;
+
+} // namespace android::display
diff --git a/services/surfaceflinger/Display/PhysicalDisplay.h b/services/surfaceflinger/Display/PhysicalDisplay.h
index ef36234..9b1f1ed 100644
--- a/services/surfaceflinger/Display/PhysicalDisplay.h
+++ b/services/surfaceflinger/Display/PhysicalDisplay.h
@@ -25,6 +25,7 @@
 #include <utils/StrongPointer.h>
 
 #include "DisplaySnapshot.h"
+#include "DisplaySnapshotRef.h"
 
 namespace android::display {
 
@@ -45,8 +46,7 @@
 
     // Transformers for PhysicalDisplays::get.
 
-    using SnapshotRef = std::reference_wrapper<const DisplaySnapshot>;
-    SnapshotRef snapshotRef() const { return std::cref(mSnapshot); }
+    DisplaySnapshotRef snapshotRef() const { return std::cref(mSnapshot); }
 
     bool isInternal() const {
         return mSnapshot.connectionType() == ui::DisplayConnectionType::Internal;