libpower: add stress test

Test: libpower_test
Change-Id: I971e9c792d1d44a7c11b746fea880fdf28015753
diff --git a/power_test.cpp b/power_test.cpp
new file mode 100644
index 0000000..bb8e97d
--- /dev/null
+++ b/power_test.cpp
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2018 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 <hardware_legacy/power.h>
+
+#include <string>
+#include <thread>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+namespace android {
+
+// Stress test acquiring/releasing WakeLocks.
+TEST(LibpowerTest, WakeLockStressTest) {
+    // numThreads threads will acquire/release numLocks locks each.
+    constexpr int numThreads = 20;
+    constexpr int numLocks = 10000;
+    std::vector<std::thread> tds;
+
+    for (int i = 0; i < numThreads; i++) {
+        tds.emplace_back([i] {
+            for (int j = 0; j < numLocks; j++) {
+                // We want ids to be unique.
+                std::string id = std::to_string(i) + "/" + std::to_string(j);
+                ASSERT_EQ(acquire_wake_lock(PARTIAL_WAKE_LOCK, id.c_str()), 0);
+                ASSERT_EQ(release_wake_lock(id.c_str()), 0);
+            }
+        });
+    }
+    for (auto& td : tds) {
+        td.join();
+    }
+}
+
+}  // namespace android