tests: support the timer source tests on Windows

PR #453 provides an initial implementation for timer support on Windows. Support
building and running the `DISPATCH_SOURCE_TYPE_TIMER` tests so we can easily
verify that timers work correctly.

These tests should pass on Windows with this and #453 applied:

- dispatch_drift
- dispatch_suspend_timer
- dispatch_timer
- dispatch_timer_bit31
- dispatch_timer_bit63
- dispatch_timer_set_time
- dispatch_timer_short
- dispatch_timer_timeout

Author: adierking

tests/CMakeLists.txt

@@ -192,8 +192,10 @@ add_unit_test(dispatch_c99 NO_BSD_OVERLAY SOURCES dispatch_c99.c)
 add_unit_test(dispatch_plusplus SOURCES dispatch_plusplus.cpp)
 
 # test-specific link options
-target_link_libraries(dispatch_group PRIVATE m)
-target_link_libraries(dispatch_timer_short PRIVATE m)
+if(NOT WIN32)
+  target_link_libraries(dispatch_group PRIVATE m)
+  target_link_libraries(dispatch_timer_short PRIVATE m)
+endif()
 
 # test-specific compile options
 set_target_properties(dispatch_c99 PROPERTIES C_STANDARD 99)

tests/dispatch_drift.c

@@ -22,8 +22,8 @@
 #include <mach/mach_time.h>
 #endif
 #include <dispatch/dispatch.h>
-#include <sys/time.h>
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+#include <sys/time.h>
 #include <unistd.h>
 #endif
 #include <stdio.h>
@@ -46,8 +46,13 @@ main(int argc __attribute__((unused)), char* argv[] __attribute__((unused)))
 	__block uint32_t count = 0;
 	__block double last_jitter = 0;
 	__block double drift_sum = 0;
+#if defined(_WIN32)
+	// 25 times a second (Windows timer resolution is poor)
+	uint64_t interval = 1000000000 / 25;
+#else
 	// 100 times a second
 	uint64_t interval = 1000000000 / 100;
+#endif
 	double interval_d = interval / 1000000000.0;
 	// for 25 seconds
 	unsigned int target = (unsigned int)(25.0 / interval_d);

tests/dispatch_timer_bit31.c

@@ -21,7 +21,9 @@
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <sys/time.h>
+#endif
 
 #include <dispatch/dispatch.h>
 

tests/dispatch_timer_bit63.c

@@ -21,7 +21,9 @@
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <sys/time.h>
+#endif
 
 #include <dispatch/dispatch.h>
 

tests/dispatch_timer_set_time.c

@@ -18,11 +18,12 @@
  * @APPLE_APACHE_LICENSE_HEADER_END@
  */
 
-#include <sys/time.h>
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <sys/time.h>
+#endif
 
 #include <dispatch/dispatch.h>
 

tests/dispatch_timer_timeout.c

@@ -21,7 +21,9 @@
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <sys/time.h>
+#endif
 
 #include <dispatch/dispatch.h>
 

tests/generic_win_port.c

@@ -183,18 +183,50 @@ gettimeofday(struct timeval *tp, void *tzp)
 	return 0;
 }
 
+typedef void (WINAPI *QueryUnbiasedInterruptTimePreciseT)(PULONGLONG);
+static QueryUnbiasedInterruptTimePreciseT QueryUnbiasedInterruptTimePrecisePtr;
+
+static BOOL
+mach_absolute_time_init(PINIT_ONCE InitOnce, PVOID Parameter, PVOID *lpContext)
+{
+	// QueryUnbiasedInterruptTimePrecise() is declared in the Windows headers
+	// but it isn't available in any import libraries. We must manually load it
+	// from KernelBase.dll.
+	HMODULE kernelbase = LoadLibraryW(L"KernelBase.dll");
+	if (!kernelbase) {
+		print_winapi_error("LoadLibraryW", GetLastError());
+		abort();
+	}
+	QueryUnbiasedInterruptTimePrecisePtr =
+			(QueryUnbiasedInterruptTimePreciseT)GetProcAddress(kernelbase,
+					"QueryUnbiasedInterruptTimePrecise");
+	if (!QueryUnbiasedInterruptTimePrecisePtr) {
+		fprintf(stderr, "QueryUnbiasedInterruptTimePrecise is not available\n");
+		abort();
+	}
+	return TRUE;
+}
+
+uint64_t
+mach_absolute_time(void)
+{
+	static INIT_ONCE init_once = INIT_ONCE_STATIC_INIT;
+	if (!InitOnceExecuteOnce(&init_once, mach_absolute_time_init, NULL, NULL)) {
+		print_winapi_error("InitOnceExecuteOnce", GetLastError());
+		abort();
+	}
+	ULONGLONG result = 0;
+	QueryUnbiasedInterruptTimePrecisePtr(&result);
+	return result * 100;  // Convert from 100ns units
+}
+
 void
 print_winapi_error(const char *function_name, DWORD error)
 {
 	char *message = NULL;
 	DWORD len = FormatMessageA(
-			FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
-			NULL,
-			error,
-			0,
-			(LPSTR)&message,
-			0,
-			NULL);
+			FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,
+			error, 0, (LPSTR)&message, 0, NULL);
 	if (len > 0) {
 		// Note: FormatMessage includes a newline at the end of the message
 		fprintf(stderr, "%s: %s", function_name, message);
@@ -214,10 +246,6 @@ sleep(unsigned int seconds)
 int
 usleep(unsigned int usec)
 {
-	DWORD ms = usec / 1000;
-	if (ms == 0 && usec != 0) {
-		ms = 1;
-	}
-	Sleep(ms);
+	Sleep((usec + 999) / 1000);
 	return 0;
 }

tests/generic_win_port.h

@@ -12,6 +12,14 @@ typedef long long ssize_t;
 typedef long ssize_t;
 #endif
 
+struct mach_timebase_info {
+	uint32_t numer;
+	uint32_t denom;
+};
+
+typedef struct mach_timebase_info *mach_timebase_info_t;
+typedef struct mach_timebase_info mach_timebase_info_data_t;
+
 static inline int32_t
 OSAtomicIncrement32(volatile int32_t *var)
 {
@@ -45,6 +53,18 @@ getpid(void);
 int
 gettimeofday(struct timeval *tp, void *tzp);
 
+uint64_t
+mach_absolute_time(void);
+
+static inline
+int
+mach_timebase_info(mach_timebase_info_t tbi)
+{
+	tbi->numer = 1;
+	tbi->denom = 1;
+	return 0;
+}
+
 void
 print_winapi_error(const char *function_name, DWORD error);