Merge pull request #12905 from kjbracey-arm/timer_tweaks

Timer: minor revisions

Author: 0xc0170

TESTS/mbed_drivers/timer/main.cpp

@@ -660,6 +660,91 @@ void test_timer_time_measurement()
     TEST_ASSERT_DURATION_WITHIN(delta(wait_val), wait_val, p_timer->elapsed_time());
 }
 
+/* This test verifies if a timer can be successfully copied.
+ *
+ * For this test Timer which uses os ticker
+ * must be used.
+ *
+ * Given timer is created
+ * Delay occurs
+ * Timer is copied
+ * Timer is stopped
+ * Timer is copied again
+ * Delay occurs
+ * Then original timer and second copy should have measured first delay.
+ * First copy should have measured both delays.
+ */
+template<int wait_val_us>
+void test_timer_copying()
+{
+    microseconds wait_val(wait_val_us);
+    const Timer &original = *static_cast<Timer *>(p_timer);
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait <wait_val_us> us. */
+    busy_wait(wait_val);
+
+    /* Copy the timer */
+    Timer running_copy{original};
+
+    /* Stop the original timer. */
+    p_timer->stop();
+
+    /* Copy the timer */
+    Timer stopped_copy{original};
+
+    /* Wait <wait_val_us> us. */
+    busy_wait(wait_val);
+
+    /* Stop the running copy. */
+    running_copy.stop();
+
+    /* Check results. */
+    TEST_ASSERT_DURATION_WITHIN(delta(wait_val), wait_val, p_timer->elapsed_time());
+    TEST_ASSERT_EQUAL_DURATION(p_timer->elapsed_time(), stopped_copy.elapsed_time());
+    TEST_ASSERT_DURATION_WITHIN(delta(wait_val * 2), wait_val * 2, running_copy.elapsed_time());
+}
+
+/* This test verifies if a timer can be successfully moved.
+ *
+ * For this test Timer which uses os ticker
+ * must be used.
+ *
+ * Given timer is created
+ * Delay occurs
+ * Timer is moved
+ * Delay occurs
+ * Then moved timer should have measured both delays.
+ */
+template<int wait_val_us>
+void test_timer_moving()
+{
+    microseconds wait_val(wait_val_us);
+    Timer &original = *static_cast<Timer *>(p_timer);
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait <wait_val_us> us. */
+    busy_wait(wait_val);
+
+    /* Move the timer */
+    Timer moved_timer{std::move(original)};
+
+    /* No longer valid to do anything with the original, other than destroy it (happens in cleanup) */
+
+    /* Wait <wait_val_us> us. */
+    busy_wait(wait_val);
+
+    /* Stop the moved timer . */
+    moved_timer.stop();
+
+    /* Check results. */
+    TEST_ASSERT_DURATION_WITHIN(delta(wait_val * 2), wait_val * 2, moved_timer.elapsed_time());
+}
+
 utest::v1::status_t test_setup(const size_t number_of_cases)
 {
     GREENTEA_SETUP(15, "default_auto");
@@ -683,6 +768,9 @@ Case cases[] = {
     Case("Test: Timer - time measurement 10 ms.", timer_os_ticker_setup_handler, test_timer_time_measurement<10000>, timer_os_ticker_cleanup_handler),
     Case("Test: Timer - time measurement 100 ms.", timer_os_ticker_setup_handler, test_timer_time_measurement<100000>, timer_os_ticker_cleanup_handler),
     Case("Test: Timer - time measurement 1 s.", timer_os_ticker_setup_handler, test_timer_time_measurement<1000000>, timer_os_ticker_cleanup_handler),
+
+    Case("Test: Timer - copying 5 ms.", timer_os_ticker_setup_handler, test_timer_copying<5000>, timer_os_ticker_cleanup_handler),
+    Case("Test: Timer - moving 5 ms.", timer_os_ticker_setup_handler, test_timer_moving<5000>, timer_os_ticker_cleanup_handler),
 };
 
 Specification specification(test_setup, cases);

drivers/Timer.h

@@ -22,6 +22,9 @@
 #include "platform/NonCopyable.h"
 
 namespace mbed {
+
+class CriticalSectionLock;
+
 /**
  * \defgroup drivers_Timer Timer class
  * \ingroup drivers-public-api-ticker
@@ -51,7 +54,7 @@ namespace mbed {
  * }
  * @endcode
  */
-class TimerBase : private NonCopyable<TimerBase> {
+class TimerBase {
 
 public:
     /** Start the timer
@@ -109,13 +112,24 @@ class TimerBase : private NonCopyable<TimerBase> {
 protected:
     TimerBase(const ticker_data_t *data);
     TimerBase(const ticker_data_t *data, bool lock_deepsleep);
+    TimerBase(const TimerBase &t);
+    TimerBase(TimerBase &&t);
     ~TimerBase();
+
+    const TimerBase &operator=(const TimerBase &) = delete;
+
     std::chrono::microseconds slicetime() const;
     TickerDataClock::time_point _start{};   // the start time of the latest slice
     std::chrono::microseconds _time{};    // any accumulated time from previous slices
     TickerDataClock _ticker_data;
     bool _lock_deepsleep;    // flag that indicates if deep sleep should be disabled
     bool _running = false;   // whether the timer is running
+
+private:
+    // Copy storage while a lock is held
+    TimerBase(const TimerBase &t, const CriticalSectionLock &) : TimerBase(t, false) {}
+    // Copy storage only - used by delegating constructors
+    TimerBase(const TimerBase &t, bool) : _start(t._start), _time(t._time), _ticker_data(t._ticker_data), _lock_deepsleep(t._lock_deepsleep), _running(t._running) {}
 };
 #endif
 

drivers/source/Timer.cpp

@@ -38,6 +38,26 @@ TimerBase::TimerBase(const ticker_data_t *data, bool lock_deepsleep) : _ticker_d
     reset();
 }
 
+// This creates a temporary CriticalSectionLock while we delegate to the
+// constructor that does the copy, thus holding critical section during the copy,
+// ensuring locking on the source. Then continue our own initialization
+// outside the critical section
+TimerBase::TimerBase(const TimerBase &t) : TimerBase(t, CriticalSectionLock{})
+{
+    // If running, new copy needs an extra lock
+    if (_running && _lock_deepsleep) {
+        sleep_manager_lock_deep_sleep();
+    }
+}
+
+// Unlike copy constructor, no need for lock on move - we must be only person
+// accessing source.
+TimerBase::TimerBase(TimerBase &&t) : TimerBase(t, false)
+{
+    // Original is marked as no longer running - we adopt any lock it had
+    t._running = false;
+}
+
 TimerBase::~TimerBase()
 {
     if (_running) {