commit 36dced862c21c7cfdb73ff9aa85e5c2b45739add
author Dominik Laskowski <domlaskowski@google.com> Fri Sep 02 09:24:00 2022 -0700
committer Dominik Laskowski <domlaskowski@google.com> Tue Oct 04 16:42:25 2022 -0400
tree b4d5c8056b8f4bba33f6f6b12b8bdfbafd0c0f9b
parent 788945b09717718b0db50dc8f16ac779b99a9490

SF: Refactor setter for DM and override policy

Move DisplayDevice::setRefreshRatePolicy to RefreshRateConfigs, and
merge the repetitive set{DisplayManager,Override}Policy helpers.

Improve type correctness of the parameters and return value.

Bug: 241285191
Test: libsurfaceflinger_unittest
Change-Id: Iee87316e5702282b828bc3f28cd7d30041030ed5

services/surfaceflinger/Scheduler/RefreshRateConfigs.h

diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 8b89104..2c2e34a 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -21,6 +21,7 @@
 #include <optional>
 #include <type_traits>
 #include <utility>
+#include <variant>
 
 #include <gui/DisplayEventReceiver.h>
 
@@ -67,8 +68,7 @@
     static constexpr nsecs_t MARGIN_FOR_PERIOD_CALCULATION =
             std::chrono::nanoseconds(800us).count();
 
-    struct Policy {
-    private:
+    class Policy {
         static constexpr int kAllowGroupSwitchingDefault = false;
 
     public:
@@ -118,23 +118,28 @@
         std::string toString() const;
     };
 
-    // Return code set*Policy() to indicate the current policy is unchanged.
-    static constexpr int CURRENT_POLICY_UNCHANGED = 1;
+    enum class SetPolicyResult { Invalid, Unchanged, Changed };
 
     // We maintain the display manager policy and the override policy separately. The override
     // policy is used by CTS tests to get a consistent device state for testing. While the override
     // policy is set, it takes precedence over the display manager policy. Once the override policy
     // is cleared, we revert to using the display manager policy.
+    struct DisplayManagerPolicy : Policy {
+        using Policy::Policy;
+    };
 
-    // Sets the display manager policy to choose refresh rates. The return value will be:
-    //   - A negative value if the policy is invalid or another error occurred.
-    //   - NO_ERROR if the policy was successfully updated, and the current policy is different from
-    //     what it was before the call.
-    //   - CURRENT_POLICY_UNCHANGED if the policy was successfully updated, but the current policy
-    //     is the same as it was before the call.
-    status_t setDisplayManagerPolicy(const Policy& policy) EXCLUDES(mLock);
-    // Sets the override policy. See setDisplayManagerPolicy() for the meaning of the return value.
-    status_t setOverridePolicy(const std::optional<Policy>& policy) EXCLUDES(mLock);
+    struct OverridePolicy : Policy {
+        using Policy::Policy;
+    };
+
+    struct NoOverridePolicy {};
+
+    using PolicyVariant = std::variant<DisplayManagerPolicy, OverridePolicy, NoOverridePolicy>;
+
+    SetPolicyResult setPolicy(const PolicyVariant&) EXCLUDES(mLock) REQUIRES(kMainThreadContext);
+
+    void onModeChangeInitiated() REQUIRES(kMainThreadContext) { mNumModeSwitchesInPolicy++; }
+
     // Gets the current policy, which will be the override policy if active, and the display manager
     // policy otherwise.
     Policy getCurrentPolicy() const EXCLUDES(mLock);
@@ -418,6 +423,8 @@
     Policy mDisplayManagerPolicy GUARDED_BY(mLock);
     std::optional<Policy> mOverridePolicy GUARDED_BY(mLock);
 
+    unsigned mNumModeSwitchesInPolicy GUARDED_BY(kMainThreadContext) = 0;
+
     mutable std::mutex mLock;
 
     // A sorted list of known frame rates that a Heuristic layer will choose