Limiting timeouts to a minimum of 3ms to avoid problems with polls and waits if timeout is 0

HISTORY

@@ -10119,7 +10119,7 @@ Video Disk Recorder Revision History
 - Now deleting old recording info before reading modified info file (suggested by
   Stefan Hofmann).
 
-2025-04-18:
+2025-06-17:
 
 - Fixed some misplaced 'override' keywords in the 'hello' and 'skincurses' plugins.
 - cRecording now fetches priority, lifetime and framesPerSecond from cRecordingInfo.
@@ -10128,3 +10128,4 @@ Video Disk Recorder Revision History
   Haubrich).
 - Updated the Italian OSD texts (thanks to Diego Pierotto).
 - Enabled manually turning subtitles on/off in 'after rewind' mode.
+- Limiting timeouts to a minimum of 3ms to avoid problems with polls and waits if timeout is 0.

thread.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: thread.c 5.3 2025/01/15 08:43:12 kls Exp $
+ * $Id: thread.c 5.4 2025/06/17 20:32:06 kls Exp $
  */
 
 #include "thread.h"
@@ -40,6 +40,7 @@ static bool GetAbsTime(struct timespec *Abstime, int MillisecondsFromNow)
 {
   struct timeval now;
   if (gettimeofday(&now, NULL) == 0) {           // get current time
+     MillisecondsFromNow  = max(MillisecondsFromNow, 3); // // making sure the time is >2ms to avoid possible busy waits
      now.tv_sec  += MillisecondsFromNow / 1000;  // add full seconds
      now.tv_usec += (MillisecondsFromNow % 1000) * 1000;  // add microseconds
      if (now.tv_usec >= 1000000) {               // take care of an overflow
@@ -72,7 +73,7 @@ cCondWait::~cCondWait()
 void cCondWait::SleepMs(int TimeoutMs)
 {
   cCondWait w;
-  w.Wait(max(TimeoutMs, 3)); // making sure the time is >2ms to avoid a possible busy wait
+  w.Wait(TimeoutMs);
 }
 
 bool cCondWait::Wait(int TimeoutMs)

tools.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.c 5.15 2025/01/15 08:57:45 kls Exp $
+ * $Id: tools.c 5.16 2025/06/17 20:32:06 kls Exp $
  */
 
 #include "tools.h"
@@ -1585,7 +1585,7 @@ void cPoller::Del(int FileHandle, bool Out)
 bool cPoller::Poll(int TimeoutMs)
 {
   if (numFileHandles) {
-     if (poll(pfd, numFileHandles, TimeoutMs) != 0)
+     if (poll(pfd, numFileHandles, max(TimeoutMs, 3)) != 0) // can't let it be 0, otherwise poll() returns immediately, even if no file descriptors are ready
         return true; // returns true even in case of an error, to let the caller
                      // access the file and thus see the error code
      }