Add Chrono support to Semaphore

Author: kjbracey

rtos/Semaphore.h

@@ -24,9 +24,11 @@
 #define SEMAPHORE_H
 
 #include <stdint.h>
+#include <chrono>
 #include "rtos/mbed_rtos_types.h"
 #include "rtos/mbed_rtos1_types.h"
 #include "rtos/mbed_rtos_storage.h"
+#include "rtos/Kernel.h"
 #include "platform/mbed_toolchain.h"
 #include "platform/NonCopyable.h"
 
@@ -81,9 +83,19 @@ class Semaphore : private mbed::NonCopyable<Semaphore> {
       @return true if a resource was acquired, false otherwise.
 
       @note You may call this function from ISR context if the millisec parameter is set to 0.
+      @deprecated Pass a chrono duration, not an integer millisecond count. For example use `5s` rather than `5000`.
     */
+    MBED_DEPRECATED_SINCE("mbed-os-6.0.0", "Pass a chrono duration, not an integer millisecond count. For example use `5s` rather than `5000`.")
     bool try_acquire_for(uint32_t millisec);
 
+    /** Wait until a Semaphore resource becomes available.
+       @param   rel_time  timeout value.
+       @return true if a resource was acquired, false otherwise.
+
+       @note You may call this function from ISR context if the rel_time parameter is set to 0.
+     */
+    bool try_acquire_for(Kernel::Clock::duration_u32 rel_time);
+
     /** Wait until a Semaphore resource becomes available.
       @param   millisec  absolute timeout time, referenced to Kernel::get_ms_count()
       @return true if a resource was acquired, false otherwise.
@@ -93,9 +105,24 @@ class Semaphore : private mbed::NonCopyable<Semaphore> {
             the acquire attempt will time out earlier than specified.
 
       @note You cannot call this function from ISR context.
+      @deprecated Pass a chrono time_point, not an integer millisecond count. For example use
+                  `Kernel::Clock::now() + 5s` rather than `Kernel::get_ms_count() + 5000`.
     */
+    MBED_DEPRECATED_SINCE("mbed-os-6.0.0", "Pass a chrono time_point, not an integer millisecond count. For example use `Kernel::Clock::now() + 5s` rather than `Kernel::get_ms_count() + 5000`.")
     bool try_acquire_until(uint64_t millisec);
 
+    /** Wait until a Semaphore resource becomes available.
+      @param   millisec  absolute timeout time, referenced to Kernel::get_ms_count()
+      @return true if a resource was acquired, false otherwise.
+      @note the underlying RTOS may have a limit to the maximum wait time
+            due to internal 32-bit computations, but this is guaranteed to work if the
+            wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded,
+            the acquire attempt will time out earlier than specified.
+
+      @note You cannot call this function from ISR context.
+    */
+    bool try_acquire_until(Kernel::Clock::time_point abs_time);
+
     /** Release a Semaphore resource that was obtain with Semaphore::acquire.
       @return status code that indicates the execution status of the function:
               @a osOK the token has been correctly released.

rtos/source/Semaphore.cpp

@@ -29,6 +29,10 @@
 
 #include <string.h>
 
+using namespace std::chrono_literals;
+using std::chrono::duration;
+using std::milli;
+
 namespace rtos {
 
 Semaphore::Semaphore(int32_t count)
@@ -104,43 +108,53 @@ void Semaphore::acquire()
 }
 
 bool Semaphore::try_acquire_for(uint32_t millisec)
+{
+    return try_acquire_for(duration<uint32_t, milli>(millisec));
+}
+
+bool Semaphore::try_acquire_for(Kernel::Clock::duration_u32 rel_time)
 {
 #if MBED_CONF_RTOS_PRESENT
-    osStatus_t status = osSemaphoreAcquire(_id, millisec);
+    osStatus_t status = osSemaphoreAcquire(_id, rel_time.count());
     if (status == osOK) {
         return true;
     }
 
-    bool success = (status == osErrorResource && millisec == 0) ||
-                   (status == osErrorTimeout && millisec != osWaitForever);
+    bool success = (status == osErrorResource && rel_time == rel_time.zero()) ||
+                   (status == osErrorTimeout);
 
     if (!success) {
         MBED_ERROR1(MBED_MAKE_ERROR(MBED_MODULE_KERNEL, MBED_ERROR_CODE_SEMAPHORE_LOCK_FAILED), "Semaphore acquire failed", status);
     }
     return false;
 #else
     sem_wait_capture capture = { this, false };
-    mbed::internal::do_timed_sleep_relative_or_forever(millisec, semaphore_available, &capture);
+    mbed::internal::do_timed_sleep_relative_or_forever(rel_time, semaphore_available, &capture);
     return capture.acquired;
 #endif
 }
 
 bool Semaphore::try_acquire_until(uint64_t millisec)
+{
+    return try_acquire_until(Kernel::Clock::time_point(duration<uint64_t, milli>(millisec)));
+}
+
+bool Semaphore::try_acquire_until(Kernel::Clock::time_point abs_time)
 {
 #if MBED_CONF_RTOS_PRESENT
-    uint64_t now = Kernel::get_ms_count();
+    Kernel::Clock::time_point now = Kernel::Clock::now();
 
-    if (now >= millisec) {
+    if (now >= abs_time) {
         return try_acquire();
-    } else if (millisec - now >= osWaitForever) {
+    } else if (abs_time - now > Kernel::wait_for_u32_max) {
         // API permits early return
-        return try_acquire_for(osWaitForever - 1);
+        return try_acquire_for(Kernel::wait_for_u32_max);
     } else {
-        return try_acquire_for(millisec - now);
+        return try_acquire_for(abs_time - now);
     }
 #else
     sem_wait_capture capture = { this, false };
-    mbed::internal::do_timed_sleep_absolute(millisec, semaphore_available, &capture);
+    mbed::internal::do_timed_sleep_absolute(abs_time, semaphore_available, &capture);
     return capture.acquired;
 #endif
 }