NNAPI Concurrent Query Management -- HAL and VTS update

The NNAPI requires requests on a model to be asynchronously
processed. This CL implements a basic Event that can later
be used to block the runtime thread until the asynchronous
request has completed.

Bug: 63905942
Test: VtsHalNeuralnetworksV1_0TargetTest (32-bit, 64-bit) with sample driver enabled by cherry-pick
      frameworks/ml/nn/runtime/test with and without sample driver enabled
Change-Id: Ie27a574aaaac312e7cbb731750f9c06278357a1c
diff --git a/neuralnetworks/1.0/vts/functional/Event.cpp b/neuralnetworks/1.0/vts/functional/Event.cpp
new file mode 100644
index 0000000..0fab86b
--- /dev/null
+++ b/neuralnetworks/1.0/vts/functional/Event.cpp
@@ -0,0 +1,76 @@
+#include "Event.h"
+#include <android-base/logging.h>
+
+namespace android {
+namespace hardware {
+namespace neuralnetworks {
+namespace V1_0 {
+namespace implementation {
+
+Event::Event() : mStatus(Status::WAITING) {}
+
+Event::~Event() {
+    if (mThread.joinable()) {
+        mThread.join();
+    }
+}
+
+Return<void> Event::notify(ReturnedStatus status) {
+    {
+        std::lock_guard<std::mutex> lock(mMutex);
+        mStatus = status == ReturnedStatus::SUCCESS ? Status::SUCCESS : Status::ERROR;
+        if (mStatus == Status::SUCCESS && mCallback != nullptr) {
+            bool success = mCallback();
+            if (!success) {
+                LOG(ERROR) << "Event::notify -- callback failed";
+            }
+        }
+    }
+    mCondition.notify_all();
+    return Void();
+}
+
+Event::Status Event::poll() {
+    std::lock_guard<std::mutex> lock(mMutex);
+    return mStatus;
+}
+
+Event::Status Event::wait() {
+    std::unique_lock<std::mutex> lock(mMutex);
+    mCondition.wait(lock, [this]{return mStatus != Status::WAITING;});
+    return mStatus;
+}
+
+bool Event::on_finish(std::function<bool(void)> callback) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    if (mCallback != nullptr) {
+        LOG(ERROR) << "Event::on_finish -- a callback has already been bound to this event";
+        return false;
+    }
+    if (callback == nullptr) {
+        LOG(ERROR) << "Event::on_finish -- the new callback is invalid";
+        return false;
+    }
+    mCallback = std::move(callback);
+    return true;
+}
+
+bool Event::bind_thread(std::thread&& asyncThread) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    if (mThread.joinable()) {
+        LOG(ERROR) << "Event::bind_thread -- a thread has already been bound to this event";
+        return false;
+    }
+    if (!asyncThread.joinable()) {
+        LOG(ERROR) << "Event::bind_thread -- the new thread is not joinable";
+        return false;
+    }
+    mThread = std::move(asyncThread);
+    return true;
+}
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace neuralnetworks
+}  // namespace hardware
+}  // namespace android