File indexing completed on 2024-05-12 15:56:59

 /*
  *  SPDX-FileCopyrightText: 2013 Dmitry Kazakov <dimula73@gmail.com>
  *
  *  SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 /**
  * KisSignalCompressor will never trigger timeout more often than every \p delay ms,
  * i.e. \p delay ms is a given lower limit defining the highest frequency.
  *
  * The current implementation uses a long-running monitor timer to eliminate the
  * overhead incurred by restarting and stopping timers with each signal. The
  * consequence of this is that the given \p delay ms is not always exactly followed.
  *
  * KisSignalCompressor makes the following callback guarantees (0 < err <= 1, with
  * err == 0 if this is the first signal after a while):
  *
  * POSTPONE:
  *   - timeout after = [0.5 ... 1.0] * \p delay ms.
  * FIRST_ACTIVE_POSTPONE_NEXT:
  *   - first timeout immediately
  *   - postponed timeout after [0.5 ... 1.0] * \p delay ms
  * FIRST_ACTIVE:
  *   - first timeout immediately
  *   - after that [0.5 ... 1.5] * \p delay ms
   * FIRST_INACTIVE:
  *   - timeout after [0.5 ... 1.5] * \p delay ms
  */
 
 #include "kis_signal_compressor.h"
 
 #include <QTimer>
 #include "kis_assert.h"
 #include "kis_debug.h"
 
 
 KisSignalCompressor::KisSignalCompressor()
     : QObject(0)
     , m_timer(new QTimer(this))
 {
     m_timer->setSingleShot(false);
     connect(m_timer, SIGNAL(timeout()), SLOT(slotTimerExpired()));
 }
 
 KisSignalCompressor::KisSignalCompressor(int delay, Mode mode, QObject *parent)
     : KisSignalCompressor(delay, mode, PRECISE_INTERVAL, parent)
 {
 }
 
 KisSignalCompressor::KisSignalCompressor(int delay, Mode mode, SlowHandlerMode slowHandlerMode, QObject *parent)
     : QObject(parent),
       m_timer(new QTimer(this)),
       m_mode(mode),
       m_slowHandlerMode(slowHandlerMode),
       m_timeout(delay)
 {
     m_timer->setSingleShot(false);
     m_timer->setInterval(delay);
     connect(m_timer, SIGNAL(timeout()), SLOT(slotTimerExpired()));
 }
 
 void KisSignalCompressor::setDelayImpl(int delay)
 {
     const bool wasActive = m_timer->isActive();
 
     if (wasActive) {
         m_timer->stop();
     }
 
     m_timer->setInterval(delay);
 
     if (wasActive) {
         m_timer->start();
     }
 }
 
 void KisSignalCompressor::setDelay(int delay)
 {
     m_timeout = delay;
     m_idleCallback = {};
     setDelayImpl(delay);
 }
 
 void KisSignalCompressor::setDelay(std::function<bool ()> idleCallback, int idleDelay, int timeout)
 {
     m_timeout = timeout;
     m_idleCallback = idleCallback;
     setDelayImpl(idleDelay);
 }
 
 void KisSignalCompressor::start()
 {
     KIS_SAFE_ASSERT_RECOVER_RETURN(m_mode != UNDEFINED);
 
     const bool isFirstStart = !m_timer->isActive();
 
     KIS_SAFE_ASSERT_RECOVER_NOOP(!isFirstStart || !m_signalsPending);
 
     switch (m_mode) {
     case POSTPONE:
         if (isFirstStart) {
             m_timer->start();
         }
         m_lastEmittedTimer.restart();
         m_signalsPending = true;
         break;
     case FIRST_ACTIVE_POSTPONE_NEXT:
     case FIRST_ACTIVE:
         if (isFirstStart) {
             m_timer->start();
             if (m_slowHandlerMode == PRECISE_INTERVAL) {
                 m_lastEmittedTimer.restart();
             }
             m_signalsPending = false;
             if (!tryEmitSignalSafely()) {
                 m_signalsPending = true;
             }
             if (m_slowHandlerMode == ADDITIVE_INTERVAL) {
                 m_lastEmittedTimer.restart();
             }
         } else {
             if (m_mode == FIRST_ACTIVE) {
                 m_signalsPending = true;
                 tryEmitOnTick(false);
             } else {
                 m_lastEmittedTimer.restart();
                 m_signalsPending = true;
             }
         }
         break;
     case FIRST_INACTIVE:
         if (isFirstStart) {
             m_timer->start();
             m_lastEmittedTimer.restart();
             m_signalsPending = true;
         } else {
             m_signalsPending = true;
             tryEmitOnTick(false);
         }
     case UNDEFINED:
         ; // Should never happen, but do nothing
     };
 
     KIS_SAFE_ASSERT_RECOVER(m_timer->isActive()) {
         m_timer->start();
     }
 }
 
 bool KisSignalCompressor::tryEmitOnTick(bool isFromTimer)
 {
     bool wasEmitted = false;
 
     // we have different requirements for hi-frequency events (the mean
     // of the events rate must be min(compressorRate, eventsRate)
     const int realInterval = m_timeout;
     const int minInterval = realInterval < 100 ? 0.5 * realInterval : realInterval;
 
     // Enable for debugging:
     // ENTER_FUNCTION() << ppVar(isFromTimer) << ppVar(m_signalsPending) << m_lastEmittedTimer.elapsed() << ppVar((m_idleCallback && m_idleCallback()));
 
     if (m_signalsPending &&
             (m_lastEmittedTimer.elapsed() >= minInterval ||
              (m_idleCallback && m_idleCallback()))) {
 
         KIS_SAFE_ASSERT_RECOVER_NOOP(!isFromTimer || !m_isEmitting);
 
         if (m_slowHandlerMode == PRECISE_INTERVAL) {
             m_lastEmittedTimer.start();
         }
 
         m_signalsPending = false;
         if (!tryEmitSignalSafely()) {
             m_signalsPending = true;
         }
 
         if (m_slowHandlerMode == ADDITIVE_INTERVAL) {
             m_lastEmittedTimer.start();
         }
 
         wasEmitted = true;
     } else if (!isFromTimer) {
         m_signalsPending = true;
     }
 
     return wasEmitted;
 }
 
 bool KisSignalCompressor::tryEmitSignalSafely()
 {
     bool wasEmitted = false;
 
     m_isEmitting++;
 
     if (m_isEmitting == 1) {
         emit timeout();
         wasEmitted = true;
     }
 
     m_isEmitting--;
 
     return wasEmitted;
 }
 
 void KisSignalCompressor::slotTimerExpired()
 {
     KIS_ASSERT_RECOVER_NOOP(m_mode != UNDEFINED);
     if (!tryEmitOnTick(true)) {
         const int calmDownInterval = 5 * m_timeout;
 
         if (!m_lastEmittedTimer.isValid() ||
             m_lastEmittedTimer.elapsed() > calmDownInterval) {
 
             m_timer->stop();
         }
     }
 }
 
 void KisSignalCompressor::stop()
 {
     m_timer->stop();
     m_signalsPending = false;
     m_lastEmittedTimer.invalidate();
 }
 
 bool KisSignalCompressor::isActive() const
 {
     return m_signalsPending && m_timer->isActive();
 }
 
 void KisSignalCompressor::setMode(KisSignalCompressor::Mode mode)
 {
     m_mode = mode;
 }
 
 int KisSignalCompressor::delay() const
 {
     return m_timeout;
 }