diff --git a/media/utils/TimeCheck.cpp b/media/utils/TimeCheck.cpp
index e53d70f..0a7790f 100644
--- a/media/utils/TimeCheck.cpp
+++ b/media/utils/TimeCheck.cpp
@@ -139,22 +139,22 @@
     return getTimeCheckThread().toString();
 }
 
-TimeCheck::TimeCheck(std::string_view tag, OnTimerFunc&& onTimer, uint32_t timeoutMs,
+TimeCheck::TimeCheck(std::string_view tag, OnTimerFunc&& onTimer, uint32_t requestedTimeoutMs,
         bool crashOnTimeout)
     : mTimeCheckHandler{ std::make_shared<TimeCheckHandler>(
-            tag, std::move(onTimer), crashOnTimeout,
+            tag, std::move(onTimer), crashOnTimeout, std::chrono::milliseconds(requestedTimeoutMs),
             std::chrono::system_clock::now(), gettid()) }
-    , mTimerHandle(timeoutMs == 0
+    , mTimerHandle(requestedTimeoutMs == 0
               ? getTimeCheckThread().trackTask(mTimeCheckHandler->tag)
               : getTimeCheckThread().scheduleTask(
                       mTimeCheckHandler->tag,
                       // Pass in all the arguments by value to this task for safety.
                       // The thread could call the callback before the constructor is finished.
                       // The destructor is not blocked on callback.
-                      [ timeCheckHandler = mTimeCheckHandler ] {
-                          timeCheckHandler->onTimeout();
+                      [ timeCheckHandler = mTimeCheckHandler ](TimerThread::Handle timerHandle) {
+                          timeCheckHandler->onTimeout(timerHandle);
                       },
-                      std::chrono::milliseconds(timeoutMs))) {}
+                      std::chrono::milliseconds(requestedTimeoutMs))) {}
 
 TimeCheck::~TimeCheck() {
     if (mTimeCheckHandler) {
@@ -162,23 +162,75 @@
     }
 }
 
+/* static */
+std::string TimeCheck::analyzeTimeouts(
+        float requestedTimeoutMs, float elapsedSteadyMs, float elapsedSystemMs) {
+    // Track any OS clock issues with suspend.
+    // It is possible that the elapsedSystemMs is much greater than elapsedSteadyMs if
+    // a suspend occurs; however, we always expect the timeout ms should always be slightly
+    // less than the elapsed steady ms regardless of whether a suspend occurs or not.
+
+    std::string s("Timeout ms ");
+    s.append(std::to_string(requestedTimeoutMs))
+        .append(" elapsed steady ms ").append(std::to_string(elapsedSteadyMs))
+        .append(" elapsed system ms ").append(std::to_string(elapsedSystemMs));
+
+    // Is there something unusual?
+    static constexpr float TOLERANCE_CONTEXT_SWITCH_MS = 200.f;
+
+    if (requestedTimeoutMs > elapsedSteadyMs || requestedTimeoutMs > elapsedSystemMs) {
+        s.append("\nError: early expiration - "
+                "requestedTimeoutMs should be less than elapsed time");
+    }
+
+    if (elapsedSteadyMs > elapsedSystemMs + TOLERANCE_CONTEXT_SWITCH_MS) {
+        s.append("\nWarning: steady time should not advance faster than system time");
+    }
+
+    // This has been found in suspend stress testing.
+    if (elapsedSteadyMs > requestedTimeoutMs + TOLERANCE_CONTEXT_SWITCH_MS) {
+        s.append("\nWarning: steady time significantly exceeds timeout "
+                "- possible thread stall or aborted suspend");
+    }
+
+    // This has been found in suspend stress testing.
+    if (elapsedSystemMs > requestedTimeoutMs + TOLERANCE_CONTEXT_SWITCH_MS) {
+        s.append("\nInformation: system time significantly exceeds timeout "
+                "- possible suspend");
+    }
+    return s;
+}
+
+// To avoid any potential race conditions, the timer handle
+// (expiration = clock steady start + timeout) is passed into the callback.
 void TimeCheck::TimeCheckHandler::onCancel(TimerThread::Handle timerHandle) const
 {
     if (TimeCheck::getTimeCheckThread().cancelTask(timerHandle) && onTimer) {
-        const std::chrono::system_clock::time_point endTime = std::chrono::system_clock::now();
-        onTimer(false /* timeout */,
-                std::chrono::duration_cast<std::chrono::duration<float, std::milli>>(
-                        endTime - startTime).count());
+        const std::chrono::steady_clock::time_point endSteadyTime =
+                std::chrono::steady_clock::now();
+        const float elapsedSteadyMs = std::chrono::duration_cast<FloatMs>(
+                endSteadyTime - timerHandle + timeoutDuration).count();
+        // send the elapsed steady time for statistics.
+        onTimer(false /* timeout */, elapsedSteadyMs);
     }
 }
 
-void TimeCheck::TimeCheckHandler::onTimeout() const
+// To avoid any potential race conditions, the timer handle
+// (expiration = clock steady start + timeout) is passed into the callback.
+void TimeCheck::TimeCheckHandler::onTimeout(TimerThread::Handle timerHandle) const
 {
-    const std::chrono::system_clock::time_point endTime = std::chrono::system_clock::now();
+    const std::chrono::steady_clock::time_point endSteadyTime = std::chrono::steady_clock::now();
+    const std::chrono::system_clock::time_point endSystemTime = std::chrono::system_clock::now();
+    // timerHandle incorporates the timeout
+    const float elapsedSteadyMs = std::chrono::duration_cast<FloatMs>(
+            endSteadyTime - (timerHandle - timeoutDuration)).count();
+    const float elapsedSystemMs = std::chrono::duration_cast<FloatMs>(
+            endSystemTime - startSystemTime).count();
+    const float requestedTimeoutMs = std::chrono::duration_cast<FloatMs>(
+            timeoutDuration).count();
+
     if (onTimer) {
-        onTimer(true /* timeout */,
-                std::chrono::duration_cast<std::chrono::duration<float, std::milli>>(
-                        endTime - startTime).count());
+        onTimer(true /* timeout */, elapsedSteadyMs);
     }
 
     if (!crashOnTimeout) return;
@@ -208,8 +260,10 @@
     // Create abort message string - caution: this can be very large.
     const std::string abortMessage = std::string("TimeCheck timeout for ")
             .append(tag)
-            .append(" scheduled ").append(formatTime(startTime))
+            .append(" scheduled ").append(formatTime(startSystemTime))
             .append(" on thread ").append(std::to_string(tid)).append("\n")
+            .append(analyzeTimeouts(
+                    requestedTimeoutMs, elapsedSteadyMs, elapsedSystemMs)).append("\n")
             .append(halPids).append("\n")
             .append(summary);
 
@@ -241,7 +295,7 @@
                     } else {
                         stats->event(safeMethodName.asStringView(), elapsedMs);
                     }
-            }, 0 /* timeoutMs */);
+            }, 0 /* requestedTimeoutMs */);
 }
 
 }  // namespace android::mediautils
diff --git a/media/utils/TimerThread-test.cpp b/media/utils/TimerThread-test.cpp
index 93cd64c..deb743a 100644
--- a/media/utils/TimerThread-test.cpp
+++ b/media/utils/TimerThread-test.cpp
@@ -36,7 +36,10 @@
 TEST(TimerThread, Basic) {
     std::atomic<bool> taskRan = false;
     TimerThread thread;
-    thread.scheduleTask("Basic", [&taskRan] { taskRan = true; }, 100ms);
+    TimerThread::Handle handle =
+            thread.scheduleTask("Basic", [&taskRan](TimerThread::Handle handle __unused) {
+                    taskRan = true; }, 100ms);
+    ASSERT_TRUE(TimerThread::isTimeoutHandle(handle));
     std::this_thread::sleep_for(100ms - kJitter);
     ASSERT_FALSE(taskRan);
     std::this_thread::sleep_for(2 * kJitter);
@@ -48,7 +51,9 @@
     std::atomic<bool> taskRan = false;
     TimerThread thread;
     TimerThread::Handle handle =
-            thread.scheduleTask("Cancel", [&taskRan] { taskRan = true; }, 100ms);
+            thread.scheduleTask("Cancel", [&taskRan](TimerThread::Handle handle __unused) {
+                    taskRan = true; }, 100ms);
+    ASSERT_TRUE(TimerThread::isTimeoutHandle(handle));
     std::this_thread::sleep_for(100ms - kJitter);
     ASSERT_FALSE(taskRan);
     ASSERT_TRUE(thread.cancelTask(handle));
@@ -61,7 +66,10 @@
     std::atomic<bool> taskRan = false;
     TimerThread thread;
     TimerThread::Handle handle =
-            thread.scheduleTask("CancelAfterRun", [&taskRan] { taskRan = true; }, 100ms);
+            thread.scheduleTask("CancelAfterRun",
+                    [&taskRan](TimerThread::Handle handle __unused) {
+                            taskRan = true; }, 100ms);
+    ASSERT_TRUE(TimerThread::isTimeoutHandle(handle));
     std::this_thread::sleep_for(100ms + kJitter);
     ASSERT_TRUE(taskRan);
     ASSERT_FALSE(thread.cancelTask(handle));
@@ -74,12 +82,18 @@
 
     auto startTime = std::chrono::steady_clock::now();
 
-    thread.scheduleTask("0", [&taskRan] { taskRan[0] = true; }, 300ms);
-    thread.scheduleTask("1", [&taskRan] { taskRan[1] = true; }, 100ms);
-    thread.scheduleTask("2", [&taskRan] { taskRan[2] = true; }, 200ms);
-    thread.scheduleTask("3", [&taskRan] { taskRan[3] = true; }, 400ms);
-    auto handle4 = thread.scheduleTask("4", [&taskRan] { taskRan[4] = true; }, 200ms);
-    thread.scheduleTask("5", [&taskRan] { taskRan[5] = true; }, 200ms);
+    thread.scheduleTask("0", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[0] = true; }, 300ms);
+    thread.scheduleTask("1", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[1] = true; }, 100ms);
+    thread.scheduleTask("2", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[2] = true; }, 200ms);
+    thread.scheduleTask("3", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[3] = true; }, 400ms);
+    auto handle4 = thread.scheduleTask("4", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[4] = true; }, 200ms);
+    thread.scheduleTask("5", [&taskRan](TimerThread::Handle handle __unused) {
+            taskRan[5] = true; }, 200ms);
 
     // 6 tasks pending
     ASSERT_EQ(6, countChars(thread.pendingToString(), REQUEST_START));
@@ -178,6 +192,10 @@
     auto handle1 = thread.trackTask("1");
     auto handle2 = thread.trackTask("2");
 
+    ASSERT_TRUE(TimerThread::isNoTimeoutHandle(handle0));
+    ASSERT_TRUE(TimerThread::isNoTimeoutHandle(handle1));
+    ASSERT_TRUE(TimerThread::isNoTimeoutHandle(handle2));
+
     // 3 tasks pending
     ASSERT_EQ(3, countChars(thread.pendingToString(), REQUEST_START));
     // 0 tasks retired
@@ -201,6 +219,7 @@
 
     // Add another tracked task.
     auto handle3 = thread.trackTask("3");
+    ASSERT_TRUE(TimerThread::isNoTimeoutHandle(handle3));
 
     // 2 tasks pending
     ASSERT_EQ(2, countChars(thread.pendingToString(), REQUEST_START));
diff --git a/media/utils/TimerThread.cpp b/media/utils/TimerThread.cpp
index 09783ed..4999de8 100644
--- a/media/utils/TimerThread.cpp
+++ b/media/utils/TimerThread.cpp
@@ -25,16 +25,20 @@
 #include <mediautils/TimerThread.h>
 #include <utils/ThreadDefs.h>
 
+using namespace std::chrono_literals;
+
 namespace android::mediautils {
 
 extern std::string formatTime(std::chrono::system_clock::time_point t);
 extern std::string_view timeSuffix(std::string_view time1, std::string_view time2);
 
 TimerThread::Handle TimerThread::scheduleTask(
-        std::string_view tag, std::function<void()>&& func, std::chrono::milliseconds timeout) {
+        std::string_view tag, TimerCallback&& func, Duration timeoutDuration) {
     const auto now = std::chrono::system_clock::now();
-    auto request = std::make_shared<const Request>(now, now + timeout, gettid(), tag);
-    return mMonitorThread.add(std::move(request), std::move(func), timeout);
+    auto request = std::make_shared<const Request>(now, now +
+            std::chrono::duration_cast<std::chrono::system_clock::duration>(timeoutDuration),
+            gettid(), tag);
+    return mMonitorThread.add(std::move(request), std::move(func), timeoutDuration);
 }
 
 TimerThread::Handle TimerThread::trackTask(std::string_view tag) {
@@ -44,7 +48,7 @@
 }
 
 bool TimerThread::cancelTask(Handle handle) {
-    std::shared_ptr<const Request> request = mNoTimeoutMap.isValidHandle(handle) ?
+    std::shared_ptr<const Request> request = isNoTimeoutHandle(handle) ?
              mNoTimeoutMap.remove(handle) : mMonitorThread.remove(handle);
     if (!request) return false;
     mRetiredQueue.add(std::move(request));
@@ -125,12 +129,12 @@
     std::vector<std::shared_ptr<const Request>> pendingExact;
     std::vector<std::shared_ptr<const Request>> pendingPossible;
 
-    // We look at pending requests that were scheduled no later than kDuration
+    // We look at pending requests that were scheduled no later than kPendingDuration
     // after the timeout request. This prevents false matches with calls
     // that naturally block for a short period of time
     // such as HAL write() and read().
     //
-    auto constexpr kDuration = std::chrono::milliseconds(1000);
+    constexpr Duration kPendingDuration = 1000ms;
     for (const auto& pending : pendingRequests) {
         // If the pending tid is the same as timeout tid, problem identified.
         if (pending->tid == timeout->tid) {
@@ -139,7 +143,7 @@
         }
 
         // if the pending tid is scheduled within time limit
-        if (pending->scheduled - timeout->scheduled < kDuration) {
+        if (pending->scheduled - timeout->scheduled < kPendingDuration) {
             pendingPossible.emplace_back(pending);
         }
     }
@@ -239,15 +243,11 @@
     }
 }
 
-bool TimerThread::NoTimeoutMap::isValidHandle(Handle handle) const {
-    return handle > getIndexedHandle(mNoTimeoutRequests);
-}
-
 TimerThread::Handle TimerThread::NoTimeoutMap::add(std::shared_ptr<const Request> request) {
     std::lock_guard lg(mNTMutex);
     // A unique handle is obtained by mNoTimeoutRequests.fetch_add(1),
     // This need not be under a lock, but we do so anyhow.
-    const Handle handle = getIndexedHandle(mNoTimeoutRequests++);
+    const Handle handle = getUniqueHandle_l();
     mMap[handle] = request;
     return handle;
 }
@@ -269,16 +269,6 @@
     }
 }
 
-TimerThread::Handle TimerThread::MonitorThread::getUniqueHandle_l(
-        std::chrono::milliseconds timeout) {
-    // To avoid key collisions, advance by 1 tick until the key is unique.
-    auto deadline = std::chrono::steady_clock::now() + timeout;
-    for (; mMonitorRequests.find(deadline) != mMonitorRequests.end();
-         deadline += std::chrono::steady_clock::duration(1))
-        ;
-    return deadline;
-}
-
 TimerThread::MonitorThread::MonitorThread(RequestQueue& timeoutQueue)
         : mTimeoutQueue(timeoutQueue)
         , mThread([this] { threadFunc(); }) {
@@ -307,10 +297,12 @@
                     _l.unlock();
                     // We add Request to retired queue early so that it can be dumped out.
                     mTimeoutQueue.add(std::move(node.mapped().first));
-                    node.mapped().second(); // Caution: we don't hold lock here - but do we care?
-                                            // this is the timeout case!  We will crash soon,
-                                            // maybe before returning.
-                    // anything left over is released here outside lock.
+                    node.mapped().second(nextDeadline);
+                    // Caution: we don't hold lock when we call TimerCallback.
+                    // This is benign issue - we permit concurrent operations
+                    // while in the callback to the MonitorQueue.
+                    //
+                    // Anything left over is released here outside lock.
                 }
                 // reacquire the lock - if something was added, we loop immediately to check.
                 _l.lock();
@@ -324,8 +316,7 @@
 }
 
 TimerThread::Handle TimerThread::MonitorThread::add(
-        std::shared_ptr<const Request> request, std::function<void()>&& func,
-        std::chrono::milliseconds timeout) {
+        std::shared_ptr<const Request> request, TimerCallback&& func, Duration timeout) {
     std::lock_guard _l(mMutex);
     const Handle handle = getUniqueHandle_l(timeout);
     mMonitorRequests.emplace(handle, std::make_pair(std::move(request), std::move(func)));
@@ -340,7 +331,7 @@
         return {};
     }
     std::shared_ptr<const TimerThread::Request> request = std::move(it->second.first);
-    std::function<void()> func = std::move(it->second.second);
+    TimerCallback func = std::move(it->second.second);
     mMonitorRequests.erase(it);
     ul.unlock();  // manually release lock here so func is released outside of lock.
     return request;
diff --git a/media/utils/include/mediautils/TimeCheck.h b/media/utils/include/mediautils/TimeCheck.h
index 038e7dd..8bee8d1 100644
--- a/media/utils/include/mediautils/TimeCheck.h
+++ b/media/utils/include/mediautils/TimeCheck.h
@@ -27,9 +27,23 @@
 
 class TimeCheck {
   public:
+
+    // Duration for TimeCheck is based on steady_clock, typically nanoseconds.
+    using Duration = std::chrono::steady_clock::duration;
+
+    // Duration for printing is in milliseconds, using float for additional precision.
+    using FloatMs = std::chrono::duration<float, std::milli>;
+
+    // OnTimerFunc is the callback function with 2 parameters.
+    //  bool timeout  (which is true when the TimeCheck object
+    //                 times out, false when the TimeCheck object is
+    //                 destroyed or leaves scope before the timer expires.)
+    //  float elapsedMs (the elapsed time to this event).
     using OnTimerFunc = std::function<void(bool /* timeout */, float /* elapsedMs */ )>;
 
     // The default timeout is chosen to be less than system server watchdog timeout
+    // Note: kDefaultTimeOutMs should be no less than 2 seconds, otherwise spurious timeouts
+    // may occur with system suspend.
     static constexpr uint32_t kDefaultTimeOutMs = 5000;
 
     /**
@@ -44,24 +58,20 @@
      * the deallocation.
      *
      * \param tag       string associated with the TimeCheck object.
-     * \param onTimer   callback function with 2 parameters
-     *                      bool timeout  (which is true when the TimeCheck object
-     *                                    times out, false when the TimeCheck object is
-     *                                    destroyed or leaves scope before the timer expires.)
-     *                      float elapsedMs (the elapsed time to this event).
+     * \param onTimer   callback function with 2 parameters (described above in OnTimerFunc).
      *                  The callback when timeout is true will be called on a different thread.
      *                  This will cancel the callback on the destructor but is not guaranteed
      *                  to block for callback completion if it is already in progress
      *                  (for maximum concurrency and reduced deadlock potential), so use proper
      *                  lifetime analysis (e.g. shared or weak pointers).
-     * \param timeoutMs timeout in milliseconds.
+     * \param requestedTimeoutMs timeout in milliseconds.
      *                  A zero timeout means no timeout is set -
      *                  the callback is called only when
      *                  the TimeCheck object is destroyed or leaves scope.
      * \param crashOnTimeout true if the object issues an abort on timeout.
      */
     explicit TimeCheck(std::string_view tag, OnTimerFunc&& onTimer = {},
-            uint32_t timeoutMs = kDefaultTimeOutMs, bool crashOnTimeout = true);
+            uint32_t requestedTimeoutMs = kDefaultTimeOutMs, bool crashOnTimeout = true);
 
     TimeCheck() = default;
     // Remove copy constructors as there should only be one call to the destructor.
@@ -81,24 +91,32 @@
     public:
         template <typename S, typename F>
         TimeCheckHandler(S&& _tag, F&& _onTimer, bool _crashOnTimeout,
-            const std::chrono::system_clock::time_point& _startTime,
+            Duration _timeoutDuration,
+            std::chrono::system_clock::time_point _startSystemTime,
             pid_t _tid)
             : tag(std::forward<S>(_tag))
             , onTimer(std::forward<F>(_onTimer))
             , crashOnTimeout(_crashOnTimeout)
-            , startTime(_startTime)
+            , timeoutDuration(_timeoutDuration)
+            , startSystemTime(_startSystemTime)
             , tid(_tid)
             {}
         const FixedString62 tag;
         const OnTimerFunc onTimer;
         const bool crashOnTimeout;
-        const std::chrono::system_clock::time_point startTime;
+        const Duration timeoutDuration;
+        const std::chrono::system_clock::time_point startSystemTime;
         const pid_t tid;
 
         void onCancel(TimerThread::Handle handle) const;
-        void onTimeout() const;
+        void onTimeout(TimerThread::Handle handle) const;
     };
 
+    // Returns a string that represents the timeout vs elapsed time,
+    // and diagnostics if there are any potential issues.
+    static std::string analyzeTimeouts(
+            float timeoutMs, float elapsedSteadyMs, float elapsedSystemMs);
+
     static TimerThread& getTimeCheckThread();
     static void accessAudioHalPids(std::vector<pid_t>* pids, bool update);
 
diff --git a/media/utils/include/mediautils/TimerThread.h b/media/utils/include/mediautils/TimerThread.h
index 349bffd..ff3ef4b 100644
--- a/media/utils/include/mediautils/TimerThread.h
+++ b/media/utils/include/mediautils/TimerThread.h
@@ -36,19 +36,93 @@
  */
 class TimerThread {
   public:
-    // A Handle is a time_point that serves as a unique key.  It is ordered.
+    // A Handle is a time_point that serves as a unique key to access a queued
+    // request to the TimerThread.
     using Handle = std::chrono::steady_clock::time_point;
 
+    // Duration is based on steady_clock (typically nanoseconds)
+    // vs the system_clock duration (typically microseconds).
+    using Duration = std::chrono::steady_clock::duration;
+
     static inline constexpr Handle INVALID_HANDLE =
             std::chrono::steady_clock::time_point::min();
 
+    // Handle implementation details:
+    // A Handle represents the timer expiration time based on std::chrono::steady_clock
+    // (clock monotonic).  This Handle is computed as now() + timeout.
+    //
+    // The lsb of the Handle time_point is adjusted to indicate whether there is
+    // a timeout action (1) or not (0).
+    //
+
+    template <size_t COUNT>
+    static constexpr bool is_power_of_2_v = COUNT > 0 && (COUNT & (COUNT - 1)) == 0;
+
+    template <size_t COUNT>
+    static constexpr size_t mask_from_count_v = COUNT - 1;
+
+    static constexpr size_t HANDLE_TYPES = 2;
+    // HANDLE_TYPES must be a power of 2.
+    static_assert(is_power_of_2_v<HANDLE_TYPES>);
+
+    // The handle types
+    enum class HANDLE_TYPE : size_t {
+        NO_TIMEOUT = 0,
+        TIMEOUT = 1,
+    };
+
+    static constexpr size_t HANDLE_TYPE_MASK = mask_from_count_v<HANDLE_TYPES>;
+
+    template <typename T>
+    static constexpr auto enum_as_value(T x) {
+        return static_cast<std::underlying_type_t<T>>(x);
+    }
+
+    static inline bool isNoTimeoutHandle(Handle handle) {
+        return (handle.time_since_epoch().count() & HANDLE_TYPE_MASK) ==
+                enum_as_value(HANDLE_TYPE::NO_TIMEOUT);
+    }
+
+    static inline bool isTimeoutHandle(Handle handle) {
+        return (handle.time_since_epoch().count() & HANDLE_TYPE_MASK) ==
+                enum_as_value(HANDLE_TYPE::TIMEOUT);
+    }
+
+    // Returns a unique Handle that doesn't exist in the container.
+    template <size_t MAX_TYPED_HANDLES, size_t HANDLE_TYPE_AS_VALUE, typename C, typename T>
+    static Handle getUniqueHandleForHandleType_l(C container, T timeout) {
+        static_assert(MAX_TYPED_HANDLES > 0 && HANDLE_TYPE_AS_VALUE < MAX_TYPED_HANDLES
+                && is_power_of_2_v<MAX_TYPED_HANDLES>,
+                " handles must be power of two");
+
+        // Our initial handle is the deadline as computed from steady_clock.
+        auto deadline = std::chrono::steady_clock::now() + timeout;
+
+        // We adjust the lsbs by the minimum increment to have the correct
+        // HANDLE_TYPE in the least significant bits.
+        auto remainder = deadline.time_since_epoch().count() & HANDLE_TYPE_MASK;
+        size_t offset = HANDLE_TYPE_AS_VALUE > remainder ? HANDLE_TYPE_AS_VALUE - remainder :
+                     MAX_TYPED_HANDLES + HANDLE_TYPE_AS_VALUE - remainder;
+        deadline += std::chrono::steady_clock::duration(offset);
+
+        // To avoid key collisions, advance the handle by MAX_TYPED_HANDLES (the modulus factor)
+        // until the key is unique.
+        while (container.find(deadline) != container.end()) {
+            deadline += std::chrono::steady_clock::duration(MAX_TYPED_HANDLES);
+        }
+        return deadline;
+    }
+
+    // TimerCallback invoked on timeout or cancel.
+    using TimerCallback = std::function<void(Handle)>;
+
     /**
      * Schedules a task to be executed in the future (`timeout` duration from now).
      *
      * \param tag     string associated with the task.  This need not be unique,
      *                as the Handle returned is used for cancelling.
      * \param func    callback function that is invoked at the timeout.
-     * \param timeout timeout duration which is converted to milliseconds with at
+     * \param timeoutDuration timeout duration which is converted to milliseconds with at
      *                least 45 integer bits.
      *                A timeout of 0 (or negative) means the timer never expires
      *                so func() is never called. These tasks are stored internally
@@ -56,7 +130,7 @@
      * \returns       a handle that can be used for cancellation.
      */
     Handle scheduleTask(
-            std::string_view tag, std::function<void()>&& func, std::chrono::milliseconds timeout);
+            std::string_view tag, TimerCallback&& func, Duration timeoutDuration);
 
     /**
      * Tracks a task that shows up on toString() until cancelled.
@@ -131,8 +205,8 @@
     // To minimize movement of data, we pass around shared_ptrs to Requests.
     // These are allocated and deallocated outside of the lock.
     struct Request {
-        Request(const std::chrono::system_clock::time_point& _scheduled,
-                const std::chrono::system_clock::time_point& _deadline,
+        Request(std::chrono::system_clock::time_point _scheduled,
+                std::chrono::system_clock::time_point _deadline,
                 pid_t _tid,
                 std::string_view _tag)
             : scheduled(_scheduled)
@@ -172,15 +246,17 @@
                 mRequestQueue GUARDED_BY(mRQMutex);
     };
 
-    // A storage map of tasks without timeouts.  There is no std::function<void()>
+    // A storage map of tasks without timeouts.  There is no TimerCallback
     // required, it just tracks the tasks with the tag, scheduled time and the tid.
     // These tasks show up on a pendingToString() until manually cancelled.
     class NoTimeoutMap {
-        // This a counter of the requests that have no timeout (timeout == 0).
-        std::atomic<size_t> mNoTimeoutRequests{};
-
         mutable std::mutex mNTMutex;
         std::map<Handle, std::shared_ptr<const Request>> mMap GUARDED_BY(mNTMutex);
+        Handle getUniqueHandle_l() REQUIRES(mNTMutex) {
+            return getUniqueHandleForHandleType_l<
+                    HANDLE_TYPES, enum_as_value(HANDLE_TYPE::NO_TIMEOUT)>(
+                mMap, Duration{} /* timeout */);
+        }
 
       public:
         bool isValidHandle(Handle handle) const; // lock free
@@ -195,11 +271,11 @@
     // This class is thread-safe.
     class MonitorThread {
         mutable std::mutex mMutex;
-        mutable std::condition_variable mCond;
+        mutable std::condition_variable mCond GUARDED_BY(mMutex);
 
         // Ordered map of requests based on time of deadline.
         //
-        std::map<Handle, std::pair<std::shared_ptr<const Request>, std::function<void()>>>
+        std::map<Handle, std::pair<std::shared_ptr<const Request>, TimerCallback>>
                 mMonitorRequests GUARDED_BY(mMutex);
 
         RequestQueue& mTimeoutQueue; // locked internally, added to when request times out.
@@ -212,14 +288,18 @@
         std::thread mThread;
 
         void threadFunc();
-        Handle getUniqueHandle_l(std::chrono::milliseconds timeout) REQUIRES(mMutex);
+        Handle getUniqueHandle_l(Duration timeout) REQUIRES(mMutex) {
+            return getUniqueHandleForHandleType_l<
+                    HANDLE_TYPES, enum_as_value(HANDLE_TYPE::TIMEOUT)>(
+                mMonitorRequests, timeout);
+        }
 
       public:
         MonitorThread(RequestQueue &timeoutQueue);
         ~MonitorThread();
 
-        Handle add(std::shared_ptr<const Request> request, std::function<void()>&& func,
-                std::chrono::milliseconds timeout);
+        Handle add(std::shared_ptr<const Request> request, TimerCallback&& func,
+                Duration timeout);
         std::shared_ptr<const Request> remove(Handle handle);
         void copyRequests(std::vector<std::shared_ptr<const Request>>& requests) const;
     };
@@ -256,16 +336,6 @@
 
     std::vector<std::shared_ptr<const Request>> getPendingRequests() const;
 
-    // A no-timeout request is represented by a handles at the end of steady_clock time,
-    // counting down by the number of no timeout requests previously requested.
-    // We manage them on the NoTimeoutMap, but conceptually they could be scheduled
-    // on the MonitorThread because those time handles won't expire in
-    // the lifetime of the device.
-    static inline Handle getIndexedHandle(size_t index) {
-        return std::chrono::time_point<std::chrono::steady_clock>::max() -
-                    std::chrono::time_point<std::chrono::steady_clock>::duration(index);
-    }
-
     static constexpr size_t kRetiredQueueMax = 16;
     RequestQueue mRetiredQueue{kRetiredQueueMax};  // locked internally