added sleep quantum correction using epicsThreadSleepQuantum()

src/libCom/timer/epicsTimer.cpp

@@ -79,10 +79,14 @@ void epicsTimerQueueActiveForC::release ()
     pMgr->release ( *this );
 }
 
-epicsTimerQueuePassiveForC::epicsTimerQueuePassiveForC 
-    ( epicsTimerQueueRescheduleCallback pCallbackIn, void * pPrivateIn ) :
+epicsTimerQueuePassiveForC::epicsTimerQueuePassiveForC ( 
+    epicsTimerQueueNotifyReschedule pRescheduleCallbackIn, 
+    epicsTimerQueueNotifyQuantum pSleepQuantumCallbackIn,
+    void * pPrivateIn ) :
         timerQueuePassive ( * static_cast < epicsTimerQueueNotify * > ( this ) ), 
-            pCallback ( pCallbackIn ), pPrivate ( pPrivateIn ) 
+        pRescheduleCallback ( pRescheduleCallbackIn ), 
+        pSleepQuantumCallback ( pSleepQuantumCallbackIn ),
+        pPrivate ( pPrivateIn )
 {
 }
 
@@ -92,7 +96,12 @@ epicsTimerQueuePassiveForC::~epicsTimerQueuePassiveForC ()
 
 void epicsTimerQueuePassiveForC::reschedule ()
 {
-    (*this->pCallback) ( this->pPrivate );
+    (*this->pRescheduleCallback) ( this->pPrivate );
+}
+
+double epicsTimerQueuePassiveForC::quantum ()
+{
+    return (*this->pSleepQuantumCallback) ( this->pPrivate );
 }
 
 void epicsTimerQueuePassiveForC::destroy ()
@@ -138,10 +147,16 @@ epicsShareFunc double epicsTimerNotify::expireStatus::expirationDelay () const
 }
 
 extern "C" epicsTimerQueuePassiveId epicsShareAPI
-    epicsTimerQueuePassiveCreate ( epicsTimerQueueRescheduleCallback pCallbackIn, void *pPrivateIn )
+    epicsTimerQueuePassiveCreate ( 
+        epicsTimerQueueNotifyReschedule pRescheduleCallbackIn, 
+        epicsTimerQueueNotifyQuantum pSleepQuantumCallbackIn,
+        void * pPrivateIn )
 {
     try {
-        return  new epicsTimerQueuePassiveForC ( pCallbackIn, pPrivateIn );
+        return new epicsTimerQueuePassiveForC ( 
+            pRescheduleCallbackIn, 
+            pSleepQuantumCallbackIn,
+            pPrivateIn );
     }
     catch ( ... ) {
         return 0;

src/libCom/timer/epicsTimer.h

@@ -89,6 +89,9 @@ public:
     // called when a new timer is inserted into the queue and the
     // delay to the next expire has changed
     virtual void reschedule () = 0;
+    // if there is a quantum in the scheduling of timer intervals
+    // return this quantum in seconds. If unknown then return zero.
+    virtual double quantum () = 0;
 protected:
     virtual ~epicsTimerQueueNotify () = 0;
 };
@@ -142,9 +145,11 @@ epicsShareFunc void  epicsShareAPI
 
 /* passive timer queue */
 typedef struct epicsTimerQueuePassiveForC * epicsTimerQueuePassiveId;
-typedef void ( *epicsTimerQueueRescheduleCallback ) ( void *pPrivate );
+typedef void ( * epicsTimerQueueNotifyReschedule ) ( void * pPrivate );
+typedef double ( * epicsTimerQueueNotifyQuantum ) ( void * pPrivate );
 epicsShareFunc epicsTimerQueuePassiveId epicsShareAPI
-    epicsTimerQueuePassiveCreate ( epicsTimerQueueRescheduleCallback, void *pPrivate );
+    epicsTimerQueuePassiveCreate ( epicsTimerQueueNotifyReschedule, 
+        epicsTimerQueueNotifyQuantum, void *pPrivate );
 epicsShareFunc void epicsShareAPI 
     epicsTimerQueuePassiveDestroy ( epicsTimerQueuePassiveId );
 epicsShareFunc epicsTimerId epicsShareAPI 

src/libCom/timer/timer.cpp

@@ -66,7 +66,7 @@ void timer::start ( epicsTimerNotify & notify, const epicsTime & expire )
 void timer::privateStart ( epicsTimerNotify & notify, const epicsTime & expire )
 {
     this->pNotify = & notify;
-    this->exp = expire;
+    this->exp = expire - this->queue.sleepQuantumOverTwo;
 
     bool reschedualNeeded = false;
     if ( this->curState == stateActive ) {

src/libCom/timer/timerPrivate.h

@@ -100,6 +100,7 @@ private:
     mutable epicsMutex mutex;
     epicsEvent cancelBlockingEvent;
     tsDLList < timer > timerList;
+    const double sleepQuantumOverTwo;
     epicsTimerQueueNotify & notify;
     timer * pExpireTmr;
     epicsThreadId processThread;
@@ -142,6 +143,7 @@ private:
     bool terminateFlag;
     void run ();
     void reschedule ();
+    double quantum ();
     epicsTimerQueue & getEpicsTimerQueue ();
 	timerQueueActive ( const timerQueueActive & );
     timerQueueActive & operator = ( const timerQueueActive & );
@@ -178,17 +180,23 @@ protected:
     timerQueuePassive & operator = ( const timerQueuePassive & );
 };
 
-struct epicsTimerQueuePassiveForC : public epicsTimerQueueNotify, public timerQueuePassive {
+struct epicsTimerQueuePassiveForC : 
+    public epicsTimerQueueNotify, public timerQueuePassive {
 public:
-    epicsTimerQueuePassiveForC ( epicsTimerQueueRescheduleCallback pCallback, void *pPrivate );
+    epicsTimerQueuePassiveForC ( 
+        epicsTimerQueueNotifyReschedule, 
+        epicsTimerQueueNotifyQuantum,
+        void * pPrivate );
     void destroy ();
 protected:
     ~epicsTimerQueuePassiveForC ();
 private:
-    epicsTimerQueueRescheduleCallback pCallback;
-    void *pPrivate;
+    epicsTimerQueueNotifyReschedule pRescheduleCallback;
+    epicsTimerQueueNotifyQuantum pSleepQuantumCallback;
+    void * pPrivate;
     static epicsSingleton < tsFreeList < epicsTimerQueuePassiveForC, 0x10 > > pFreeList;
     void reschedule ();
+    double quantum ();
 };
 
 struct epicsTimerQueueActiveForC : public timerQueueActive, 

src/libCom/timer/timerQueue.cpp

@@ -22,8 +22,9 @@
 epicsTimerQueue::~epicsTimerQueue () {}
 
 timerQueue::timerQueue ( epicsTimerQueueNotify &notifyIn ) :
+    sleepQuantumOverTwo ( notifyIn.quantum () / 2.0 ), 
     notify ( notifyIn ), pExpireTmr ( 0 ),  
-        processThread ( 0 ), cancelPending ( false )
+    processThread ( 0 ), cancelPending ( false )
 {
 }
 

src/libCom/timer/timerQueueActive.cpp

@@ -86,6 +86,11 @@ void timerQueueActive::reschedule ()
     this->rescheduleEvent.signal ();
 }
 
+double timerQueueActive::quantum ()
+{
+    return epicsThreadSleepQuantum ();
+}
+
 void timerQueueActive::show ( unsigned int level ) const
 {
     printf ( "EPICS threaded timer queue at %p\n",