diff --git a/biometrics/common/thread/Android.bp b/biometrics/common/thread/Android.bp
new file mode 100644
index 0000000..a497d01
--- /dev/null
+++ b/biometrics/common/thread/Android.bp
@@ -0,0 +1,26 @@
+cc_library {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "hardware_interfaces_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    name: "android.hardware.biometrics.common.thread",
+    export_include_dirs: ["include"],
+    vendor: true,
+    srcs: [
+        "WorkerThread.cpp",
+    ],
+}
+
+cc_test_host {
+    name: "android.hardware.biometrics.common.WorkerThreadTest",
+    local_include_dirs: ["include"],
+    srcs: [
+        "tests/WorkerThreadTest.cpp",
+        "WorkerThread.cpp",
+    ],
+    shared_libs: [
+        "libcutils",
+    ],
+    test_suites: ["general-tests"],
+}
diff --git a/biometrics/common/thread/WorkerThread.cpp b/biometrics/common/thread/WorkerThread.cpp
new file mode 100644
index 0000000..61d1a13
--- /dev/null
+++ b/biometrics/common/thread/WorkerThread.cpp
@@ -0,0 +1,71 @@
+/*
+ * 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.
+ */
+
+#include "thread/WorkerThread.h"
+
+namespace aidl::android::hardware::biometrics {
+
+// It's important that mThread is initialized after everything else because it runs a member
+// function that may use any member of this class.
+WorkerThread::WorkerThread(size_t maxQueueSize)
+    : mMaxSize(maxQueueSize),
+      mIsDestructing(false),
+      mQueue(),
+      mQueueMutex(),
+      mQueueCond(),
+      mThread(&WorkerThread::threadFunc, this) {}
+
+WorkerThread::~WorkerThread() {
+    // This is a signal for threadFunc to terminate as soon as possible, and a hint for schedule
+    // that it doesn't need to do any work.
+    {
+        std::unique_lock<std::mutex> lock(mQueueMutex);
+        mIsDestructing = true;
+    }
+    mQueueCond.notify_all();
+    mThread.join();
+}
+
+bool WorkerThread::schedule(std::unique_ptr<Callable> task) {
+    if (mIsDestructing) {
+        return false;
+    }
+
+    std::unique_lock<std::mutex> lock(mQueueMutex);
+    if (mQueue.size() >= mMaxSize) {
+        return false;
+    }
+    mQueue.push_back(std::move(task));
+    lock.unlock();
+    mQueueCond.notify_one();
+    return true;
+}
+
+void WorkerThread::threadFunc() {
+    while (!mIsDestructing) {
+        std::unique_lock<std::mutex> lock(mQueueMutex);
+        mQueueCond.wait(lock, [this] { return !mQueue.empty() || mIsDestructing; });
+        if (mIsDestructing) {
+            return;
+        }
+        std::unique_ptr<Callable> task = std::move(mQueue.front());
+        mQueue.pop_front();
+        lock.unlock();
+        (*task)();
+    }
+}
+
+}  // namespace aidl::android::hardware::biometrics
diff --git a/biometrics/common/thread/include/thread/Callable.h b/biometrics/common/thread/include/thread/Callable.h
new file mode 100644
index 0000000..6eeff76
--- /dev/null
+++ b/biometrics/common/thread/include/thread/Callable.h
@@ -0,0 +1,54 @@
+/*
+ * 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
+
+namespace aidl::android::hardware::biometrics {
+
+// Interface for representing parameterless functions. Unlike std::function<void()>, this can also
+// represent move-only lambdas.
+class Callable {
+  public:
+    virtual void operator()() = 0;
+    virtual ~Callable() = default;
+
+    // Creates a heap-allocated Callable instance from any function object.
+    template <typename T>
+    static std::unique_ptr<Callable> from(T func);
+
+  private:
+    template <typename T>
+    class AnyFuncWrapper;
+};
+
+// Private helper class for wrapping any function object into a Callable.
+template <typename T>
+class Callable::AnyFuncWrapper : public Callable {
+  public:
+    explicit AnyFuncWrapper(T func) : mFunc(std::move(func)) {}
+
+    void operator()() override { mFunc(); }
+
+  private:
+    T mFunc;
+};
+
+template <typename T>
+std::unique_ptr<Callable> Callable::from(T func) {
+    return std::make_unique<AnyFuncWrapper<T>>(std::move(func));
+}
+
+}  // namespace aidl::android::hardware::biometrics
\ No newline at end of file
diff --git a/biometrics/common/thread/include/thread/WorkerThread.h b/biometrics/common/thread/include/thread/WorkerThread.h
new file mode 100644
index 0000000..5f89a7f
--- /dev/null
+++ b/biometrics/common/thread/include/thread/WorkerThread.h
@@ -0,0 +1,79 @@
+/*
+ * 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 <mutex>
+#include <optional>
+#include <queue>
+#include <thread>
+
+#include "Callable.h"
+
+namespace aidl::android::hardware::biometrics {
+
+// A class that encapsulates a worker thread and a task queue, and provides a convenient interface
+// for a Session to schedule its tasks for asynchronous execution.
+class WorkerThread final {
+  public:
+    // Internally creates a queue that cannot exceed maxQueueSize elements and a new thread that
+    // polls the queue for tasks until this instance is destructed.
+    explicit WorkerThread(size_t maxQueueSize);
+
+    // Unblocks the internal queue and calls join on the internal thread allowing it to gracefully
+    // exit.
+    ~WorkerThread();
+
+    // Disallow copying this class.
+    WorkerThread(const WorkerThread&) = delete;
+    WorkerThread& operator=(const WorkerThread&) = delete;
+
+    // Also disable moving this class to simplify implementation.
+    WorkerThread(WorkerThread&&) = delete;
+    WorkerThread& operator=(WorkerThread&&) = delete;
+
+    // If the internal queue is not full, pushes a task at the end of the queue and returns true.
+    // Otherwise, returns false. If the queue is busy, blocks until it becomes available.
+    // This method expects heap-allocated tasks because it's the simplest way to represent function
+    // objects of any type. Stack-allocated std::function could be used instead, but it cannot
+    // represent functions with move-only captures because std::function is inherently copyable.
+    // Not being able to pass move-only lambdas is a major limitation for the HAL implementation,
+    // so heap-allocated tasks that share a common interface (Callable) were chosen instead.
+    bool schedule(std::unique_ptr<Callable> task);
+
+  private:
+    // The function that runs on the internal thread. Sequentially runs the available tasks from
+    // the queue. If the queue is empty, waits until a new task is added. If the worker is being
+    // destructed, finishes its current task and gracefully exits.
+    void threadFunc();
+
+    // The maximum size that the queue is allowed to expand to.
+    size_t mMaxSize;
+
+    // Whether the destructor was called. If true, tells threadFunc to exit as soon as possible, and
+    // tells schedule to avoid doing any work.
+    std::atomic<bool> mIsDestructing;
+
+    // Queue that's guarded by mQueueMutex and mQueueCond.
+    std::deque<std::unique_ptr<Callable>> mQueue;
+    std::mutex mQueueMutex;
+    std::condition_variable mQueueCond;
+
+    // The internal thread that works on the tasks from the queue.
+    std::thread mThread;
+};
+
+}  // namespace aidl::android::hardware::biometrics
diff --git a/biometrics/common/thread/tests/WorkerThreadTest.cpp b/biometrics/common/thread/tests/WorkerThreadTest.cpp
new file mode 100644
index 0000000..5bb9e7e
--- /dev/null
+++ b/biometrics/common/thread/tests/WorkerThreadTest.cpp
@@ -0,0 +1,138 @@
+/*
+ * 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.
+ */
+
+#include <algorithm>
+#include <chrono>
+#include <future>
+#include <thread>
+
+#include <gtest/gtest.h>
+
+#include "thread/WorkerThread.h"
+
+namespace {
+
+using namespace aidl::android::hardware::biometrics;
+using namespace std::chrono_literals;
+
+TEST(WorkerThreadTest, ScheduleReturnsTrueWhenQueueHasSpace) {
+    WorkerThread worker(1 /*maxQueueSize*/);
+    for (int i = 0; i < 100; ++i) {
+        std::promise<void> promise;
+        auto future = promise.get_future();
+
+        ASSERT_TRUE(worker.schedule(Callable::from([promise = std::move(promise)]() mutable {
+            // Notify that the task has started.
+            promise.set_value();
+        })));
+
+        future.wait();
+    }
+}
+
+TEST(WorkerThreadTest, ScheduleReturnsFalseWhenQueueIsFull) {
+    WorkerThread worker(2 /*maxQueueSize*/);
+
+    std::promise<void> promise;
+    auto future = promise.get_future();
+
+    // Schedule a long-running task.
+    ASSERT_TRUE(worker.schedule(Callable::from([promise = std::move(promise)]() mutable {
+        // Notify that the task has started.
+        promise.set_value();
+        // Block for a "very long" time.
+        std::this_thread::sleep_for(1s);
+    })));
+
+    // Make sure the long-running task began executing.
+    future.wait();
+
+    // The first task is already being worked on, which means the queue must be empty.
+    // Fill the worker's queue to the maximum.
+    ASSERT_TRUE(worker.schedule(Callable::from([] {})));
+    ASSERT_TRUE(worker.schedule(Callable::from([] {})));
+
+    EXPECT_FALSE(worker.schedule(Callable::from([] {})));
+}
+
+TEST(WorkerThreadTest, TasksExecuteInOrder) {
+    constexpr int NUM_TASKS = 10000;
+    WorkerThread worker(NUM_TASKS + 1);
+
+    std::mutex mut;
+    std::condition_variable cv;
+    bool finished = false;
+    std::vector<int> results;
+
+    for (int i = 0; i < NUM_TASKS; ++i) {
+        worker.schedule(Callable::from([&mut, &results, i] {
+            // Delay tasks differently to provoke races.
+            std::this_thread::sleep_for(std::chrono::nanoseconds(100 - i % 100));
+            auto lock = std::lock_guard(mut);
+            results.push_back(i);
+        }));
+    }
+
+    // Schedule a special task to signal when all of the tasks are finished.
+    worker.schedule(Callable::from([&mut, &cv, &finished] {
+        auto lock = std::lock_guard(mut);
+        finished = true;
+        cv.notify_one();
+    }));
+
+    auto lock = std::unique_lock(mut);
+    cv.wait(lock, [&finished] { return finished; });
+    ASSERT_EQ(results.size(), NUM_TASKS);
+    EXPECT_TRUE(std::is_sorted(results.begin(), results.end()));
+}
+
+TEST(WorkerThreadTest, ExecutionStopsAfterWorkerIsDestroyed) {
+    std::promise<void> promise1;
+    std::promise<void> promise2;
+    auto future1 = promise1.get_future();
+    auto future2 = promise2.get_future();
+    std::atomic<bool> value;
+
+    // Local scope for the worker to test its destructor when it goes out of scope.
+    {
+        WorkerThread worker(2 /*maxQueueSize*/);
+
+        ASSERT_TRUE(worker.schedule(Callable::from([promise = std::move(promise1)]() mutable {
+            promise.set_value();
+            std::this_thread::sleep_for(200ms);
+        })));
+
+        // The first task should start executing.
+        future1.wait();
+
+        // The second task should schedule successfully.
+        ASSERT_TRUE(
+                worker.schedule(Callable::from([promise = std::move(promise2), &value]() mutable {
+                    // The worker should destruct before it gets a chance to execute this.
+                    value = true;
+                    promise.set_value();
+                })));
+    }
+
+    // The second task should never execute.
+    future2.wait();
+    // The future is expected to be ready but contain an exception.
+    // Cannot use ASSERT_THROW because exceptions are disabled in this codebase.
+    // ASSERT_THROW(future2.get(), std::future_error);
+    EXPECT_FALSE(value);
+}
+
+}  // namespace
diff --git a/biometrics/common/util/Android.bp b/biometrics/common/util/Android.bp
new file mode 100644
index 0000000..918ef72
--- /dev/null
+++ b/biometrics/common/util/Android.bp
@@ -0,0 +1,18 @@
+cc_library {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "hardware_interfaces_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    name: "android.hardware.biometrics.common.util",
+    export_include_dirs: ["include"],
+    vendor: true,
+    srcs: [
+        "CancellationSignal.cpp",
+    ],
+    shared_libs: [
+        "libbase",
+        "libbinder_ndk",
+        "android.hardware.biometrics.common-V2-ndk",
+    ],
+}
diff --git a/biometrics/common/util/CancellationSignal.cpp b/biometrics/common/util/CancellationSignal.cpp
new file mode 100644
index 0000000..7888838
--- /dev/null
+++ b/biometrics/common/util/CancellationSignal.cpp
@@ -0,0 +1,37 @@
+/*
+ * 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.
+ */
+
+#include "util/CancellationSignal.h"
+
+#include <android-base/logging.h>
+#include <chrono>
+
+namespace aidl::android::hardware::biometrics {
+
+CancellationSignal::CancellationSignal(std::promise<void>&& cancellationPromise)
+    : mCancellationPromise(std::move(cancellationPromise)) {}
+
+ndk::ScopedAStatus CancellationSignal::cancel() {
+    mCancellationPromise.set_value();
+    return ndk::ScopedAStatus::ok();
+}
+
+bool shouldCancel(const std::future<void>& f) {
+    CHECK(f.valid());
+    return f.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
+}
+
+}  // namespace aidl::android::hardware::biometrics
diff --git a/biometrics/common/util/include/util/CancellationSignal.h b/biometrics/common/util/include/util/CancellationSignal.h
new file mode 100644
index 0000000..be77e29
--- /dev/null
+++ b/biometrics/common/util/include/util/CancellationSignal.h
@@ -0,0 +1,39 @@
+/*
+ * 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 <functional>
+#include <future>
+
+namespace aidl::android::hardware::biometrics {
+
+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