SF: Add TransactionHandler

- migrate transaction queueing and flushing into
  a new class and remove dependencies from
  other components.
- Add a filter interface for other components to
  participate in transactionready logic.

Test: presubmit
Bug: 238781169
Change-Id: Ia4da386cd72058126f6f765adafb9cb4d15b1d2b
diff --git a/services/surfaceflinger/TransactionHandler.h b/services/surfaceflinger/TransactionHandler.h
new file mode 100644
index 0000000..237b48d
--- /dev/null
+++ b/services/surfaceflinger/TransactionHandler.h
@@ -0,0 +1,74 @@
+/*
+ * 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 <semaphore.h>
+#include <cstdint>
+#include <mutex>
+#include <queue>
+#include <thread>
+#include <vector>
+
+#include <LocklessQueue.h>
+#include <TransactionState.h>
+#include <android-base/thread_annotations.h>
+#include <ftl/small_map.h>
+#include <ftl/small_vector.h>
+
+namespace android {
+class TransactionHandler {
+public:
+    struct TransactionFlushState {
+        const TransactionState* transaction;
+        bool firstTransaction = true;
+        nsecs_t queueProcessTime = 0;
+        // Layer handles that have transactions with buffers that are ready to be applied.
+        ftl::SmallMap<IBinder* /* binder address */, uint64_t /* framenumber */, 15>
+                bufferLayersReadyToPresent = {};
+        ftl::SmallVector<IBinder* /* queueToken */, 15> queuesWithUnsignaledBuffers;
+    };
+    enum class TransactionReadiness {
+        NotReady,
+        NotReadyBarrier,
+        Ready,
+        ReadyUnsignaled,
+        ReadyUnsignaledSingle,
+    };
+    using TransactionFilter = std::function<TransactionReadiness(const TransactionFlushState&)>;
+
+    bool hasPendingTransactions();
+    std::vector<TransactionState> flushTransactions();
+    void addTransactionReadyFilter(TransactionFilter&&);
+    void queueTransaction(TransactionState&&);
+    void onTransactionQueueStalled(const TransactionState&, sp<ITransactionCompletedListener>&);
+    void removeFromStalledTransactions(uint64_t transactionId);
+
+private:
+    // For unit tests
+    friend class TestableSurfaceFlinger;
+
+    int flushPendingTransactionQueues(std::vector<TransactionState>&, TransactionFlushState&);
+    TransactionReadiness applyFilters(TransactionFlushState&);
+    std::unordered_map<sp<IBinder>, std::queue<TransactionState>, IListenerHash>
+            mPendingTransactionQueues;
+    LocklessQueue<TransactionState> mLocklessTransactionQueue;
+    std::atomic<size_t> mPendingTransactionCount = 0;
+    ftl::SmallVector<TransactionFilter, 2> mTransactionReadyFilters;
+    std::vector<uint64_t> mStalledTransactions;
+};
+
+} // namespace android