/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file pipelineCyclerTrueImpl.I
 * @author drose
 * @date 2006-01-31
 */

/**
 * Grabs an overall lock on the cycler.  Release it with a call to release().
 * This lock should be held while walking the list of stages.
 */
INLINE void PipelineCyclerTrueImpl::
acquire() {
  TAU_PROFILE("void PipelineCyclerTrueImpl::acquire()", " ", TAU_USER);
  _lock.acquire();
}

/**
 * Grabs an overall lock on the cycler.  Release it with a call to release().
 * This lock should be held while walking the list of stages.
 */
INLINE void PipelineCyclerTrueImpl::
acquire(Thread *current_thread) {
  TAU_PROFILE("void PipelineCyclerTrueImpl::acquire(Thread *)", " ", TAU_USER);
  _lock.acquire(current_thread);
}

/**
 * Release the overall lock on the cycler that was grabbed via acquire().
 */
INLINE void PipelineCyclerTrueImpl::
release() {
  TAU_PROFILE("void PipelineCyclerTrueImpl::release()", " ", TAU_USER);
  _lock.release();
}

/**
 * Returns a const CycleData pointer, filled with the data for the current
 * stage of the pipeline as seen by this thread.  No lock is made on the
 * contents; there is no guarantee that some other thread won't modify this
 * object's data while you are working on it.  (However, the data within the
 * returned CycleData object itself is safe from modification; if another
 * thread modifies the data, it will perform a copy-on-write, and thereby
 * change the pointer stored within the object.)
 */
INLINE const CycleData *PipelineCyclerTrueImpl::
read_unlocked(Thread *current_thread) const {
  TAU_PROFILE("const CycleData *PipelineCyclerTrueImpl::read_unlocked(Thread *)", " ", TAU_USER);
  int pipeline_stage = current_thread->get_pipeline_stage();
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
#endif
  return _data[pipeline_stage]._cdata;
}

/**
 * Returns a const CycleData pointer, filled with the data for the current
 * stage of the pipeline as seen by this thread.  This pointer should
 * eventually be released by calling release_read().
 *
 * There should be no outstanding write pointers on the data when this
 * function is called.
 */
INLINE const CycleData *PipelineCyclerTrueImpl::
read(Thread *current_thread) const {
  TAU_PROFILE("const CycleData *PipelineCyclerTrueImpl::read(Thread *)", " ", TAU_USER);
  int pipeline_stage = current_thread->get_pipeline_stage();
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
#endif
  _lock.acquire(current_thread);
  return _data[pipeline_stage]._cdata;
}

/**
 * Increments the count on a pointer previously retrieved by read(); now the
 * pointer will need to be released twice.
 */
INLINE void PipelineCyclerTrueImpl::
increment_read(const CycleData *pointer) const {
  TAU_PROFILE("void PipelineCyclerTrueImpl::increment_read(const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  int pipeline_stage = Thread::get_current_pipeline_stage();
  nassertv(pipeline_stage >= 0 && pipeline_stage < _num_stages);
  nassertv(_data[pipeline_stage]._cdata == pointer);
#endif
  _lock.elevate_lock();
}

/**
 * Releases a pointer previously obtained via a call to read().
 */
INLINE void PipelineCyclerTrueImpl::
release_read(const CycleData *pointer) const {
  TAU_PROFILE("void PipelineCyclerTrueImpl::release_read(const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  int pipeline_stage = Thread::get_current_pipeline_stage();
  nassertv(pipeline_stage >= 0 && pipeline_stage < _num_stages);
  nassertv(_data[pipeline_stage]._cdata == pointer);
#endif
  _lock.release();
}

/**
 * Returns a non-const CycleData pointer, filled with a unique copy of the
 * data for the current stage of the pipeline as seen by this thread.  This
 * pointer may now be used to write to the data, and that copy of the data
 * will be propagated to all later stages of the pipeline.  This pointer
 * should eventually be released by calling release_write().
 *
 * There may only be one outstanding write pointer on a given stage at a time,
 * and if there is a write pointer there may be no read pointers on the same
 * stage (but see elevate_read).
 */
INLINE CycleData *PipelineCyclerTrueImpl::
write(Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::write(Thread *)", " ", TAU_USER);
  return write_stage(current_thread->get_pipeline_stage(), current_thread);
}

/**
 * This special variant on write() will automatically propagate changes back
 * to upstream pipeline stages.  If force_to_0 is false, then it propagates
 * back only as long as the CycleData pointers are equivalent, guaranteeing
 * that it does not modify upstream data (other than the modification that
 * will be performed by the code that returns this pointer).  This is
 * particularly appropriate for minor updates, where it doesn't matter much if
 * the update is lost, such as storing a cached value.
 *
 * If force_to_0 is true, then the CycleData pointer for the current pipeline
 * stage is propagated all the way back up to stage 0; after this call, there
 * will be only one CycleData pointer that is duplicated in all stages between
 * stage 0 and the current stage.  This may undo some recent changes that were
 * made independently at pipeline stage 0 (or any other upstream stage).
 * However, it guarantees that the change that is to be applied at this
 * pipeline stage will stick.  This is slightly dangerous because of the risk
 * of losing upstream changes; generally, this should only be done when you
 * are confident that there are no upstream changes to be lost (for instance,
 * for an object that has been recently created).
 */
INLINE CycleData *PipelineCyclerTrueImpl::
write_upstream(bool force_to_0, Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::write_upstream(bool, Thread *)", " ", TAU_USER);
  return write_stage_upstream(current_thread->get_pipeline_stage(), force_to_0,
                              current_thread);
}

/**
 * Elevates a currently-held read pointer into a write pointer.  This may or
 * may not change the value of the pointer.  It is only valid to do this if
 * this is the only currently-outstanding read pointer on the current stage.
 */
INLINE CycleData *PipelineCyclerTrueImpl::
elevate_read(const CycleData *pointer, Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::elevate_read(const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  int pipeline_stage = current_thread->get_pipeline_stage();
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
  nassertr(_data[pipeline_stage]._cdata == pointer, nullptr);
#endif
  CycleData *new_pointer = write(current_thread);
  _lock.release();
  return new_pointer;
}

/**
 * Elevates a currently-held read pointer into a write pointer, like
 * elevate_read(), but also propagates the pointer back to upstream stages,
 * like write_upstream().
 */
INLINE CycleData *PipelineCyclerTrueImpl::
elevate_read_upstream(const CycleData *pointer, bool force_to_0, Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::elevate_read_upstream(const CycleData *, bool)", " ", TAU_USER);
#ifdef _DEBUG
  int pipeline_stage = current_thread->get_pipeline_stage();
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
  nassertr(_data[pipeline_stage]._cdata == pointer, nullptr);
#endif
  CycleData *new_pointer = write_upstream(force_to_0, current_thread);
  _lock.release();
  return new_pointer;
}

/**
 * Increments the count on a pointer previously retrieved by write(); now the
 * pointer will need to be released twice.
 */
INLINE void PipelineCyclerTrueImpl::
increment_write(CycleData *pointer) const {
  TAU_PROFILE("void PipelineCyclerTrueImpl::increment_write(CycleData *)", " ", TAU_USER);
  int pipeline_stage = Thread::get_current_pipeline_stage();
#ifdef _DEBUG
  nassertv(pipeline_stage >= 0 && pipeline_stage < _num_stages);
  nassertv(_data[pipeline_stage]._cdata == pointer);
#endif
  ++(_data[pipeline_stage]._writes_outstanding);
  _lock.elevate_lock();
}

/**
 * Releases a pointer previously obtained via a call to write().
 */
INLINE void PipelineCyclerTrueImpl::
release_write(CycleData *pointer) {
  TAU_PROFILE("void PipelineCyclerTrueImpl::release_write(CycleData *)", " ", TAU_USER);
  int pipeline_stage = Thread::get_current_pipeline_stage();
  return release_write_stage(pipeline_stage, pointer);
}

/**
 * Returns the number of stages in the pipeline.
 */
INLINE int PipelineCyclerTrueImpl::
get_num_stages() {
  return _num_stages;
}

/**
 * Returns a const CycleData pointer, filled with the data for the indicated
 * stage of the pipeline.  As in read_unlocked(), no lock is held on the
 * returned pointer.
 */
INLINE const CycleData *PipelineCyclerTrueImpl::
read_stage_unlocked(int pipeline_stage) const {
  TAU_PROFILE("const CycleData *PipelineCyclerTrueImpl::read_stage_unlocked(int)", " ", TAU_USER);
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
#elif defined(__has_builtin) && __has_builtin(__builtin_assume)
  __builtin_assume(pipeline_stage >= 0);
#endif
  return _data[pipeline_stage]._cdata;
}

/**
 * Returns a const CycleData pointer, filled with the data for the indicated
 * stage of the pipeline.  This pointer should eventually be released by
 * calling release_read_stage().
 *
 * There should be no outstanding write pointers on the data when this
 * function is called.
 */
INLINE const CycleData *PipelineCyclerTrueImpl::
read_stage(int pipeline_stage, Thread *current_thread) const {
  TAU_PROFILE("const CycleData *PipelineCyclerTrueImpl::read_stage(int, Thread *)", " ", TAU_USER);
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
#elif defined(__has_builtin) && __has_builtin(__builtin_assume)
  __builtin_assume(pipeline_stage >= 0);
#endif
  _lock.acquire(current_thread);
  return _data[pipeline_stage]._cdata;
}

/**
 * Releases a pointer previously obtained via a call to read_stage().
 */
INLINE void PipelineCyclerTrueImpl::
release_read_stage(int pipeline_stage, const CycleData *pointer) const {
  TAU_PROFILE("void PipelineCyclerTrueImpl::release_read_stage(int, const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  nassertv(pipeline_stage >= 0 && pipeline_stage < _num_stages);
  nassertv(_data[pipeline_stage]._cdata == pointer);
#endif
  _lock.release();
}

/**
 * Elevates a currently-held read pointer into a write pointer.  This may or
 * may not change the value of the pointer.  It is only valid to do this if
 * this is the only currently-outstanding read pointer on the indicated stage.
 */
INLINE CycleData *PipelineCyclerTrueImpl::
elevate_read_stage(int pipeline_stage, const CycleData *pointer,
                   Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::elevate_read_stage(int, const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
  nassertr(_data[pipeline_stage]._cdata == pointer, nullptr);
#elif defined(__has_builtin) && __has_builtin(__builtin_assume)
  __builtin_assume(pipeline_stage >= 0);
#endif
  CycleData *new_pointer = write_stage(pipeline_stage, current_thread);
  _lock.release();
  return new_pointer;
}

/**
 * Elevates a currently-held read pointer into a write pointer.  This may or
 * may not change the value of the pointer.  It is only valid to do this if
 * this is the only currently-outstanding read pointer on the indicated stage.
 */
INLINE CycleData *PipelineCyclerTrueImpl::
elevate_read_stage_upstream(int pipeline_stage, const CycleData *pointer,
                            bool force_to_0, Thread *current_thread) {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::elevate_read_stage(int, const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
  nassertr(_data[pipeline_stage]._cdata == pointer, nullptr);
#elif defined(__has_builtin) && __has_builtin(__builtin_assume)
  __builtin_assume(pipeline_stage >= 0);
#endif
  CycleData *new_pointer =
    write_stage_upstream(pipeline_stage, force_to_0, current_thread);
  _lock.release();
  return new_pointer;
}

/**
 * Releases a pointer previously obtained via a call to write_stage().
 */
INLINE void PipelineCyclerTrueImpl::
release_write_stage(int pipeline_stage, CycleData *pointer) {
  TAU_PROFILE("void PipelineCyclerTrueImpl::release_write_stage(int, const CycleData *)", " ", TAU_USER);
#ifdef _DEBUG
  nassertv(pipeline_stage >= 0 && pipeline_stage < _num_stages);
  nassertv(_data[pipeline_stage]._cdata == pointer);
  nassertv(_data[pipeline_stage]._writes_outstanding > 0);
#elif defined(__has_builtin) && __has_builtin(__builtin_assume)
  __builtin_assume(pipeline_stage >= 0);
#endif
  --(_data[pipeline_stage]._writes_outstanding);
  _lock.release();
}

/**
 * Returns the type of object that owns this cycler, as reported by
 * CycleData::get_parent_type().
 */
INLINE TypeHandle PipelineCyclerTrueImpl::
get_parent_type() const {
  return _data[0]._cdata->get_parent_type();
}

/**
 * Returns a pointer without counting it.  This is only intended for use as
 * the return value for certain nassertr() functions, so the application can
 * recover after a failure to manage the read and write pointers correctly.
 * You should never call this function directly.
 */
INLINE CycleData *PipelineCyclerTrueImpl::
cheat() const {
  TAU_PROFILE("CycleData *PipelineCyclerTrueImpl::cheat()", " ", TAU_USER);
  int pipeline_stage = Thread::get_current_pipeline_stage();
  nassertr(pipeline_stage >= 0 && pipeline_stage < _num_stages, nullptr);
  return _data[pipeline_stage]._cdata;
}

/**
 * Returns the number of handles currently outstanding to read the current
 * stage of the data.  This should only be used for debugging purposes.
 */
INLINE int PipelineCyclerTrueImpl::
get_read_count() const {
  return 0;
}

/**
 * Returns the number of handles currently outstanding to read the current
 * stage of the data.  This will normally only be either 0 or 1.  This should
 * only be used for debugging purposes.
 */
INLINE int PipelineCyclerTrueImpl::
get_write_count() const {
  return 0;
}

/**
 * This is a special implementation of cycle() for the special case of just
 * two stages to the pipeline.  It does the same thing as cycle(), but is a
 * little bit faster because it knows there are exactly two stages.
 */
INLINE PT(CycleData) PipelineCyclerTrueImpl::
cycle_2() {
  TAU_PROFILE("PT(CycleData) PipelineCyclerTrueImpl::cycle_2()", " ", TAU_USER);

  // This trick moves an NPT into a PT without unnecessarily incrementing and
  // subsequently decrementing the regular reference count.
  PT(CycleData) last_val;
  last_val.swap(_data[1]._cdata);
  last_val->node_unref_only();

  nassertr(_lock.debug_is_locked(), last_val);
  nassertr(_dirty, last_val);
  nassertr(_num_stages == 2, last_val);

  nassertr(_data[1]._writes_outstanding == 0, last_val);
  _data[1]._cdata = _data[0]._cdata;

  // No longer dirty.
  _dirty = 0;
  return last_val;
}

/**
 * This is a special implementation of cycle() for the special case of exactly
 * three stages to the pipeline.  It does the same thing as cycle(), but is a
 * little bit faster because it knows there are exactly three stages.
 */
INLINE PT(CycleData) PipelineCyclerTrueImpl::
cycle_3() {
  TAU_PROFILE("PT(CycleData) PipelineCyclerTrueImpl::cycle_3()", " ", TAU_USER);

  // This trick moves an NPT into a PT without unnecessarily incrementing and
  // subsequently decrementing the regular reference count.
  PT(CycleData) last_val;
  last_val.swap(_data[2]._cdata);
  last_val->node_unref_only();

  nassertr(_lock.debug_is_locked(), last_val);
  nassertr(_dirty, last_val);
  nassertr(_num_stages == 3, last_val);

  nassertr(_data[2]._writes_outstanding == 0, last_val);
  nassertr(_data[1]._writes_outstanding == 0, last_val);
  _data[2]._cdata = _data[1]._cdata;
  _data[1]._cdata = _data[0]._cdata;

  if (_data[2]._cdata == _data[1]._cdata) {
    // No longer dirty.
    _dirty = 0;
  }

  return last_val;
}

/**
 *
 */
INLINE PipelineCyclerTrueImpl::CyclerMutex::
CyclerMutex(PipelineCyclerTrueImpl *cycler) {
#ifdef DEBUG_THREADS
  _cycler = cycler;
#endif
}

/**
 *
 */
INLINE PipelineCyclerTrueImpl::CycleDataNode::
CycleDataNode() :
  _writes_outstanding(0)
{
}

/**
 *
 */
INLINE PipelineCyclerTrueImpl::CycleDataNode::
CycleDataNode(const PipelineCyclerTrueImpl::CycleDataNode &copy) :
  _cdata(copy._cdata),
  _writes_outstanding(0)
{
}

/**
 *
 */
INLINE PipelineCyclerTrueImpl::CycleDataNode::
~CycleDataNode() {
  nassertv(_writes_outstanding == 0);
}

/**
 *
 */
INLINE void PipelineCyclerTrueImpl::CycleDataNode::
operator = (const PipelineCyclerTrueImpl::CycleDataNode &copy) {
  _cdata = copy._cdata;
}