etl/test/test_semaphore.cpp

/******************************************************************************
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Embedded Template Library.
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Copyright(c) 2026 Julien Hecht

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#include "clocks_for_unit_tests.h"
#include "unit_test_framework.h"

#include <thread>

#include <etl/semaphore.h>

using namespace test::clocks;

namespace
{
  SUITE(test_semaphore)
  {
    TEST(test_semaphore_counting_nominal)
    {
      int initial_count = 10;
      int release_count = 20;
      int acquire_count = initial_count + release_count;

      etl::counting_semaphore<> sem{initial_count};

      std::thread thread(
        [&sem, &release_count]()
        {
          while (release_count > 0)
          {
            sem.release();
            release_count--;
          }
        });

      while (acquire_count > 0)
      {
        sem.acquire();
        acquire_count--;
      }

      thread.join();

      CHECK_EQUAL(release_count, 0);
      CHECK_EQUAL(acquire_count, 0);
      CHECK_FALSE(sem.try_acquire());
    }

    TEST(test_semaphore_counting_try_acquire)
    {
      etl::counting_semaphore<> sem{1};

      CHECK_TRUE(sem.try_acquire());
      CHECK_FALSE(sem.try_acquire());
    }

    TEST(test_semaphore_counting_try_for)
    {
      etl::counting_semaphore<> sem{1};

      // try_for uses steady_clock in the `gcc_sync` implementation
      // (default backend if STL is not available or FreeRTOS is not enabled)
      // During testing, this means the clock used for waiting has a granularity of 1s.
      seconds = 0;
      std::thread thread(
        []()
        {
          // Just sleep a bit, not literally 1s, because that's a wait of time
          std::this_thread::sleep_for(std::chrono::milliseconds(20));
          seconds++;
        });

      CHECK_TRUE(sem.try_acquire_for(etl::chrono::milliseconds(10)));
      CHECK_FALSE(sem.try_acquire_for(etl::chrono::milliseconds(10)));

      thread.join();
    }

    TEST(test_semaphore_counting_try_until)
    {
      etl::counting_semaphore<> sem{1};

      nanoseconds = 0;
      std::thread thread(
        []()
        {
          // Count to 20 milliseconds
          for (int i = 0; i < 20; i++)
          {
            std::this_thread::sleep_for(std::chrono::milliseconds(1));
            nanoseconds += 1000000;
          }
        });

      auto now = etl::chrono::high_resolution_clock::now();
      CHECK_TRUE(sem.try_acquire_until(now + etl::chrono::milliseconds(10)));
      CHECK_FALSE(sem.try_acquire_until(now + etl::chrono::milliseconds(10)));

      thread.join();
    }

    TEST(test_semaphore_binary_nominal)
    {
      etl::binary_semaphore sem{0};

      sem.release();
      sem.acquire();

      CHECK_FALSE(sem.try_acquire());
    }

    TEST(test_semaphore_binary_try_acquire)
    {
      etl::binary_semaphore sem{1};

      CHECK_TRUE(sem.try_acquire());
      CHECK_FALSE(sem.try_acquire());
    }

    TEST(test_semaphore_binary_try_for)
    {
      etl::binary_semaphore sem{1};

      // try_for uses steady_clock in the `gcc_sync` implementation
      // (default backend if STL is not available or FreeRTOS is not enabled)
      // During testing, this means the clock used for waiting has a granularity of 1s.
      seconds = 0;
      std::thread thread(
        []()
        {
          // Just sleep a bit, not literally 1s, because that's a waste of time
          std::this_thread::sleep_for(std::chrono::milliseconds(20));
          seconds++;
        });

      CHECK_TRUE(sem.try_acquire_for(etl::chrono::milliseconds(10)));
      CHECK_FALSE(sem.try_acquire_for(etl::chrono::milliseconds(10)));

      thread.join();
    }

    TEST(test_semaphore_binary_try_until)
    {
      etl::binary_semaphore sem{1};

      nanoseconds = 0;
      std::thread thread(
        []()
        {
          // Count to 20 milliseconds
          for (int i = 0; i < 20; i++)
          {
            std::this_thread::sleep_for(std::chrono::milliseconds(1));
            nanoseconds += 1000000;
          }
        });

      auto now = etl::chrono::high_resolution_clock::now();
      CHECK_TRUE(sem.try_acquire_until(now + etl::chrono::milliseconds(10)));
      CHECK_FALSE(sem.try_acquire_until(now + etl::chrono::milliseconds(10)));

      thread.join();
    }
  }
} // namespace