Improve unit test accuracy

I didn't take clock resolution into account when created the test,
and it failed for me occasionally because the value was slightly
less than expected.

The typical system tick resolution is documented at
https://docs.microsoft.com/en-us/windows-hardware/drivers/kernel/high-resolution-timers

Change-Id: Ie48b10d15b14f9ac7d292a2cc9916bcbfff44b6f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111946
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
(cherry picked from commit eef43192d4c7b2867638c54a2ac31adfc26476c7)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/112076
Tested-by: Jenkins
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

2 files changed, 11 insertions, 11 deletions

diff --git a/include/systools/win32/retry_if_failed.hxx b/include/systools/win32/retry_if_failed.hxx
index 11a7e5372037..d3dd6b125be9 100644
--- a/include/systools/win32/retry_if_failed.hxx
+++ b/include/systools/win32/retry_if_failed.hxx
@@ -24,16 +24,12 @@ namespace sal::systools
 //     HRESULT hr = sal::systools::RetryIfFailed(10, 100, []{ return OleFlushClipboard(); });
 template <typename Func> HRESULT RetryIfFailed(unsigned times, unsigned msTimeout, Func func)
 {
-    HRESULT hr = E_FAIL;
-    for (unsigned i = 0; i < times; ++i)
+    for (unsigned i = 0;; ++i)
     {
-        hr = func();
-        if (SUCCEEDED(hr))
-            break;
-        if (i < times - 1)
-            Sleep(msTimeout);
+        if (HRESULT hr = func(); SUCCEEDED(hr) || i >= times)
+            return hr;
+        Sleep(msTimeout);
     }
-    return hr;
 }
 }
 
diff --git a/sal/qa/systools/test_retry_if_failed.cxx b/sal/qa/systools/test_retry_if_failed.cxx
index 845cba83092d..7df83cb229a1 100644
--- a/sal/qa/systools/test_retry_if_failed.cxx
+++ b/sal/qa/systools/test_retry_if_failed.cxx
@@ -13,19 +13,22 @@
 
 namespace test_systools
 {
+constexpr int ClockRes = 15; // default interval between system clock ticks is ~15 ms on x86
+
 class test_retry_if_failed : public CppUnit::TestFixture
 {
 public:
     void test_success()
     {
         const DWORD nTicksBefore = GetTickCount();
-        HRESULT hr = sal::systools::RetryIfFailed(10, 100, Tester(5));
+        HRESULT hr = sal::systools::RetryIfFailed(10, 200, Tester(5));
         const DWORD nTicksAfter = GetTickCount();
         const DWORD nTicksElapsed = nTicksAfter > nTicksBefore ? nTicksAfter - nTicksBefore
                                                                : std::numeric_limits<DWORD>::max()
                                                                      - nTicksBefore + nTicksAfter;
         CPPUNIT_ASSERT(SUCCEEDED(hr));
-        CPPUNIT_ASSERT(nTicksElapsed >= 400); // 5 attempts, 4 sleeps by 100 ms
+        // 5 attempts, 4 sleeps by ~200 ms
+        CPPUNIT_ASSERT_GREATER(DWORD(800 - ClockRes), nTicksElapsed);
     }
 
     void test_failure()
@@ -37,7 +40,8 @@ public:
                                                                : std::numeric_limits<DWORD>::max()
                                                                      - nTicksBefore + nTicksAfter;
         CPPUNIT_ASSERT(FAILED(hr));
-        CPPUNIT_ASSERT(nTicksElapsed >= 900); // 10 attempts, 9 sleeps by 100 ms
+        // 1 + 10 attempts, 10 sleeps by ~100 ms
+        CPPUNIT_ASSERT_GREATER(DWORD(1000 - ClockRes), nTicksElapsed);
     }
 
     CPPUNIT_TEST_SUITE(test_retry_if_failed);