Improve BlockingQueue and add SyncQueue

Changes to BlockingQueue:
- Change BlockingQueue to be list-backed instead of vector-backed so
  that removals are O(1) instead of O(N).
- Rename erase to erase_if.
- Make providing a fixed capacity at construction optional.
- Add emplace function to push and construct element in-place.
- Add popWithTimeout function.

Bug: 275726706
Test: atest inputflinger_tests
Change-Id: I1be02b0887df2c21b28f4f1cb43a8e208d996a87
diff --git a/services/inputflinger/tests/SyncQueue_test.cpp b/services/inputflinger/tests/SyncQueue_test.cpp
new file mode 100644
index 0000000..af2f961
--- /dev/null
+++ b/services/inputflinger/tests/SyncQueue_test.cpp
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2023 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.
+ */
+
+#include "../SyncQueue.h"
+
+#include <gtest/gtest.h>
+#include <thread>
+
+namespace android {
+
+// --- SyncQueueTest ---
+
+// Validate basic pop and push operation.
+TEST(SyncQueueTest, AddAndRemove) {
+    SyncQueue<int> queue;
+
+    queue.push(1);
+    ASSERT_EQ(queue.pop(), 1);
+
+    queue.push(3);
+    ASSERT_EQ(queue.pop(), 3);
+
+    ASSERT_EQ(std::nullopt, queue.pop());
+}
+
+// Make sure the queue maintains FIFO order.
+// Add elements and remove them, and check the order.
+TEST(SyncQueueTest, isFIFO) {
+    SyncQueue<int> queue;
+
+    constexpr int numItems = 10;
+    for (int i = 0; i < numItems; i++) {
+        queue.push(static_cast<int>(i));
+    }
+    for (int i = 0; i < numItems; i++) {
+        ASSERT_EQ(queue.pop(), static_cast<int>(i));
+    }
+}
+
+TEST(SyncQueueTest, AllowsMultipleThreads) {
+    SyncQueue<int> queue;
+
+    // Test with a large number of items to increase likelihood that threads overlap
+    constexpr int numItems = 100;
+
+    // Fill queue from a different thread
+    std::thread fillQueue([&queue]() {
+        for (int i = 0; i < numItems; i++) {
+            queue.push(static_cast<int>(i));
+        }
+    });
+
+    // Make sure all elements are received in correct order
+    for (int i = 0; i < numItems; i++) {
+        // Since popping races with the thread that's filling the queue,
+        // keep popping until we get something back
+        std::optional<int> popped;
+        do {
+            popped = queue.pop();
+        } while (!popped);
+        ASSERT_EQ(popped, static_cast<int>(i));
+    }
+
+    fillQueue.join();
+}
+
+} // namespace android