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Prevents OS::get_ticks_usec() from going backwards in time due to OS … #31863

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Prevents OS::get_ticks_usec() from going backwards in time due to OS … #31863

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57 changes: 56 additions & 1 deletion core/os/os.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,7 @@ OS *OS::get_singleton() {
return singleton;
}

uint32_t OS::get_ticks_msec() const {
uint32_t OS::get_ticks_msec() {
return get_ticks_usec() / 1000;
}

Expand Down Expand Up @@ -93,6 +93,59 @@ uint64_t OS::get_system_time_secs() const {
uint64_t OS::get_system_time_msecs() const {
return 0;
}

uint64_t OS::get_ticks_usec() {
// This is a workaround for rare OS bugs where a call to get_ticks_raw_usec()
// may return an EARLIER value than that given in a previous call.
// This ensures that the minimum delta will be zero, and prevents bugs which rely on
// the delta being positive.
uint64_t t = get_ticks_raw_usec();

// note that get_ticks_raw_usec() may return 0 if the OS API function failed.
// we will deal with this by returning the previous value
if (t == 0)
return _ticks_usec_running_total;

if (t >= _ticks_usec_prev)
{
// time going forwards, normal case
uint64_t diff = t - _ticks_usec_prev;

// cap forward time (shouldn't happen except for long stalls, but just in case)
if (diff > 100000)
{
if (diff < 1000000) {
WARN_PRINTS("OS time running forward " + itos(diff) + " usecs detected");
}
else {
WARN_PRINTS("OS time running forward " + itos(diff / 1000000) + " secs detected");
}
diff = 100000;
}

// move our own robust 'fake clock' forward
_ticks_usec_running_total += diff;
}
else
{
// time going backwards, we need to deal with this
// Do not increment running total
uint64_t diff = _ticks_usec_prev - t;

if (diff < 1000000) {
WARN_PRINTS("OS time running backward " + itos(diff) + " usecs detected");
}
else {
WARN_PRINTS("OS time running backward " + itos(diff / 1000000) + " secs detected");
}
}

// resync each time, the difference should be based on the previous value
_ticks_usec_prev = t;

return _ticks_usec_running_total;
}

void OS::debug_break(){

// something
Expand Down Expand Up @@ -769,6 +822,8 @@ OS::OS() {
_keep_screen_on = true; // set default value to true, because this had been true before godot 2.0.
low_processor_usage_mode = false;
low_processor_usage_mode_sleep_usec = 10000;
_ticks_usec_prev = 0;
_ticks_usec_running_total = 0;
_verbose_stdout = false;
_no_window = false;
_exit_code = 0;
Expand Down
8 changes: 6 additions & 2 deletions core/os/os.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,8 @@ class OS {
bool _allow_hidpi;
bool _allow_layered;
bool _use_vsync;
uint64_t _ticks_usec_prev;
uint64_t _ticks_usec_running_total;

char *last_error;

Expand Down Expand Up @@ -138,6 +140,8 @@ class OS {
void _ensure_user_data_dir();
virtual bool _check_internal_feature_support(const String &p_feature) = 0;

virtual uint64_t get_ticks_raw_usec() const = 0;

public:
typedef int64_t ProcessID;

Expand Down Expand Up @@ -344,8 +348,8 @@ class OS {
virtual uint64_t get_system_time_msecs() const;

virtual void delay_usec(uint32_t p_usec) const = 0;
virtual uint64_t get_ticks_usec() const = 0;
uint32_t get_ticks_msec() const;
uint64_t get_ticks_usec();
uint32_t get_ticks_msec();
uint64_t get_splash_tick_msec() const;

virtual bool can_draw() const = 0;
Expand Down
21 changes: 17 additions & 4 deletions drivers/unix/os_unix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -258,17 +258,30 @@ void OS_Unix::delay_usec(uint32_t p_usec) const {
while (nanosleep(&rem, &rem) == EINTR) {
}
}
uint64_t OS_Unix::get_ticks_usec() const {
uint64_t OS_Unix::get_ticks_raw_usec() const {

#if defined(__APPLE__)
uint64_t longtime = mach_absolute_time() * _clock_scale;
#else
// Unchecked return. Static analyzers might complain.
// If _setup_clock() succeeded, we assume clock_gettime() works.
struct timespec tv_now = { 0, 0 };
clock_gettime(GODOT_CLOCK, &tv_now);

int res = clock_gettime(GODOT_CLOCK, &tv_now);

// if clock_gettime failed, return zero which is dealt with by wrapper
if (res != 0)
{
WARN_PRINT_ONCE("clock_gettime failed");
return 0;
}

uint64_t longtime = ((uint64_t)tv_now.tv_nsec / 1000L) + (uint64_t)tv_now.tv_sec * 1000000L;
#endif
// _clock_start should never be ahead of longtime
if (_clock_start > longtime) {
WARN_PRINT_ONCE("_clock_start is ahead of clock_gettime");
return 0;
}

longtime -= _clock_start;

return longtime;
Expand Down
3 changes: 2 additions & 1 deletion drivers/unix/os_unix.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,8 @@ class OS_Unix : public OS {

virtual void finalize_core();

virtual uint64_t get_ticks_raw_usec() const;

String stdin_buf;

public:
Expand Down Expand Up @@ -83,7 +85,6 @@ class OS_Unix : public OS {
virtual uint64_t get_system_time_msecs() const;

virtual void delay_usec(uint32_t p_usec) const;
virtual uint64_t get_ticks_usec() const;

virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL);
virtual Error kill(const ProcessID &p_pid);
Expand Down
2 changes: 1 addition & 1 deletion platform/uwp/os_uwp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -620,7 +620,7 @@ void OS_UWP::delay_usec(uint32_t p_usec) const {
// no Sleep()
WaitForSingleObjectEx(GetCurrentThread(), msec, false);
}
uint64_t OS_UWP::get_ticks_usec() const {
uint64_t OS_UWP::get_ticks_raw_usec() const {

uint64_t ticks;
uint64_t time;
Expand Down
3 changes: 2 additions & 1 deletion platform/uwp/os_uwp.h
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Expand Up @@ -170,6 +170,8 @@ class OS_UWP : public OS {

void process_key_events();

virtual uint64_t get_ticks_raw_usec() const;

public:
// Event to send to the app wrapper
HANDLE mouse_mode_changed;
Expand Down Expand Up @@ -206,7 +208,6 @@ class OS_UWP : public OS {
virtual Error set_cwd(const String &p_cwd);

virtual void delay_usec(uint32_t p_usec) const;
virtual uint64_t get_ticks_usec() const;

virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL);
virtual Error kill(const ProcessID &p_pid);
Expand Down
2 changes: 1 addition & 1 deletion platform/windows/os_windows.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2284,7 +2284,7 @@ void OS_Windows::delay_usec(uint32_t p_usec) const {
else
Sleep(p_usec / 1000);
}
uint64_t OS_Windows::get_ticks_usec() const {
uint64_t OS_Windows::get_ticks_raw_usec() const {

uint64_t ticks;
uint64_t time;
Expand Down
3 changes: 2 additions & 1 deletion platform/windows/os_windows.h
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Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,8 @@ class OS_Windows : public OS {
void process_events();
void process_key_events();

virtual uint64_t get_ticks_raw_usec() const;

struct ProcessInfo {

STARTUPINFO si;
Expand Down Expand Up @@ -287,7 +289,6 @@ class OS_Windows : public OS {
virtual Error set_cwd(const String &p_cwd);

virtual void delay_usec(uint32_t p_usec) const;
virtual uint64_t get_ticks_usec() const;

virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL);
virtual Error kill(const ProcessID &p_pid);
Expand Down