Merge "SF: Store VsyncDispatch callbacks in ftl::SmallMap" into main

Author: Dominik Laskowski

services/surfaceflinger/Scheduler/VSyncDispatch.h

@@ -35,7 +35,7 @@ enum class CancelResult { Cancelled, TooLate, Error };
  */
 class VSyncDispatch {
 public:
-    using CallbackToken = StrongTyping<size_t, class CallbackTokenTag, Compare, Hash>;
+    using CallbackToken = StrongTyping<size_t, class CallbackTokenTag, Compare>;
 
     virtual ~VSyncDispatch();
 

services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp

@@ -267,15 +267,15 @@ void VSyncDispatchTimerQueue::setTimer(nsecs_t targetTime, nsecs_t /*now*/) {
 }
 
 void VSyncDispatchTimerQueue::rearmTimer(nsecs_t now) {
-    rearmTimerSkippingUpdateFor(now, mCallbacks.end());
+    rearmTimerSkippingUpdateFor(now, mCallbacks.cend());
 }
 
 void VSyncDispatchTimerQueue::rearmTimerSkippingUpdateFor(
-        nsecs_t now, CallbackMap::iterator const& skipUpdateIt) {
+        nsecs_t now, CallbackMap::const_iterator skipUpdateIt) {
     std::optional<nsecs_t> min;
     std::optional<nsecs_t> targetVsync;
     std::optional<std::string_view> nextWakeupName;
-    for (auto it = mCallbacks.begin(); it != mCallbacks.end(); it++) {
+    for (auto it = mCallbacks.cbegin(); it != mCallbacks.cend(); ++it) {
         auto& callback = it->second;
         if (!callback->wakeupTime() && !callback->hasPendingWorkloadUpdate()) {
             continue;
@@ -351,13 +351,12 @@ void VSyncDispatchTimerQueue::timerCallback() {
 VSyncDispatchTimerQueue::CallbackToken VSyncDispatchTimerQueue::registerCallback(
         Callback callback, std::string callbackName) {
     std::lock_guard lock(mMutex);
-    return CallbackToken{
-            mCallbacks
-                    .emplace(++mCallbackToken,
-                             std::make_shared<VSyncDispatchTimerQueueEntry>(std::move(callbackName),
-                                                                            std::move(callback),
-                                                                            mMinVsyncDistance))
-                    .first->first};
+    return mCallbacks
+            .try_emplace(CallbackToken{++mCallbackToken},
+                         std::make_shared<VSyncDispatchTimerQueueEntry>(std::move(callbackName),
+                                                                        std::move(callback),
+                                                                        mMinVsyncDistance))
+            .first->first;
 }
 
 void VSyncDispatchTimerQueue::unregisterCallback(CallbackToken token) {
@@ -367,7 +366,7 @@ void VSyncDispatchTimerQueue::unregisterCallback(CallbackToken token) {
         auto it = mCallbacks.find(token);
         if (it != mCallbacks.end()) {
             entry = it->second;
-            mCallbacks.erase(it);
+            mCallbacks.erase(it->first);
         }
     }
 

services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h

@@ -16,14 +16,13 @@
 
 #pragma once
 
-#include <functional>
 #include <memory>
 #include <mutex>
 #include <string>
 #include <string_view>
-#include <unordered_map>
 
 #include <android-base/thread_annotations.h>
+#include <ftl/small_map.h>
 
 #include "VSyncDispatch.h"
 #include "VsyncSchedule.h"
@@ -135,13 +134,14 @@ class VSyncDispatchTimerQueue : public VSyncDispatch {
     VSyncDispatchTimerQueue(const VSyncDispatchTimerQueue&) = delete;
     VSyncDispatchTimerQueue& operator=(const VSyncDispatchTimerQueue&) = delete;
 
+    // The static capacity was chosen to exceed the expected number of callbacks.
     using CallbackMap =
-            std::unordered_map<CallbackToken, std::shared_ptr<VSyncDispatchTimerQueueEntry>>;
+            ftl::SmallMap<CallbackToken, std::shared_ptr<VSyncDispatchTimerQueueEntry>, 5>;
 
     void timerCallback();
     void setTimer(nsecs_t, nsecs_t) REQUIRES(mMutex);
     void rearmTimer(nsecs_t now) REQUIRES(mMutex);
-    void rearmTimerSkippingUpdateFor(nsecs_t now, CallbackMap::iterator const& skipUpdate)
+    void rearmTimerSkippingUpdateFor(nsecs_t now, CallbackMap::const_iterator skipUpdate)
             REQUIRES(mMutex);
     void cancelTimer() REQUIRES(mMutex);
     ScheduleResult scheduleLocked(CallbackToken, ScheduleTiming) REQUIRES(mMutex);