Implement the state machine

Bug: 166800618
Bug: 175070939
Test: atest VtsHalBiometricsFingerprintTargetTest
Change-Id: I3a908b0f910323d643b220e560e9c2d8e4c5675a
diff --git a/biometrics/fingerprint/aidl/default/include/CancellationSignal.h b/biometrics/fingerprint/aidl/default/include/CancellationSignal.h
new file mode 100644
index 0000000..99f2fba
--- /dev/null
+++ b/biometrics/fingerprint/aidl/default/include/CancellationSignal.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2021 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 <aidl/android/hardware/biometrics/common/BnCancellationSignal.h>
+#include <aidl/android/hardware/biometrics/fingerprint/ISessionCallback.h>
+#include <functional>
+#include <future>
+
+#include "WorkerThread.h"
+
+namespace aidl::android::hardware::biometrics::fingerprint {
+
+class CancellationSignal : public common::BnCancellationSignal {
+  public:
+    explicit CancellationSignal(std::promise<void>&& cancellationPromise);
+
+    ndk::ScopedAStatus cancel() override;
+
+  private:
+    std::promise<void> mCancellationPromise;
+};
+
+// Returns whether the given cancellation future is ready, i.e. whether the operation corresponding
+// to this future should be cancelled.
+bool shouldCancel(const std::future<void>& cancellationFuture);
+
+}  // namespace aidl::android::hardware::biometrics::fingerprint