// Filename: renderAttrib.cxx
// Created by:  drose (21Feb02)
//
////////////////////////////////////////////////////////////////////
//
// 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."
//
////////////////////////////////////////////////////////////////////

#include "renderAttrib.h"
#include "bamReader.h"
#include "indent.h"
#include "config_pgraph.h"
#include "lightReMutexHolder.h"
#include "pStatTimer.h"

LightReMutex *RenderAttrib::_attribs_lock = NULL;
RenderAttrib::Attribs *RenderAttrib::_attribs = NULL;
TypeHandle RenderAttrib::_type_handle;

int RenderAttrib::_garbage_index = 0;

PStatCollector RenderAttrib::_garbage_collect_pcollector("*:State Cache:Garbage Collect");

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::Constructor
//       Access: Protected
//  Description:
////////////////////////////////////////////////////////////////////
RenderAttrib::
RenderAttrib() {
  if (_attribs == (Attribs *)NULL) {
    init_attribs();
  }
  _saved_entry = -1;

  _always_reissue = false;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::Copy Constructor
//       Access: Private
//  Description: RenderAttribs are not meant to be copied.
////////////////////////////////////////////////////////////////////
RenderAttrib::
RenderAttrib(const RenderAttrib &) {
  nassertv(false);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::Copy Assignment Operator
//       Access: Private
//  Description: RenderAttribs are not meant to be copied.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
operator = (const RenderAttrib &) {
  nassertv(false);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::Destructor
//       Access: Public, Virtual
//  Description: The destructor is responsible for removing the
//               RenderAttrib from the global set if it is there.
////////////////////////////////////////////////////////////////////
RenderAttrib::
~RenderAttrib() {
  LightReMutexHolder holder(*_attribs_lock);

  // unref() should have cleared this.
  nassertv(_saved_entry == -1);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::lower_attrib_can_override
//       Access: Public, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               This should return false if a RenderAttrib on a
//               higher node will compose into a RenderAttrib on a
//               lower node that has a higher override value, or true
//               if the lower RenderAttrib will completely replace the
//               state.
//
//               The default behavior is false: normally, a
//               RenderAttrib in the graph cannot completely override
//               a RenderAttrib above it, regardless of its override
//               value--instead, the two attribs are composed.  But
//               for some kinds of RenderAttribs, it is useful to
//               allow this kind of override.
//
//               This method only handles the one special case of a
//               lower RenderAttrib with a higher override value.  If
//               the higher RenderAttrib has a higher override value,
//               it always completely overrides.  And if both
//               RenderAttribs have the same override value, they are
//               always composed.
////////////////////////////////////////////////////////////////////
bool RenderAttrib::
lower_attrib_can_override() const {
  return false;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::has_cull_callback
//       Access: Public, Virtual
//  Description: Should be overridden by derived classes to return
//               true if cull_callback() has been defined.  Otherwise,
//               returns false to indicate cull_callback() does not
//               need to be called for this node during the cull
//               traversal.
////////////////////////////////////////////////////////////////////
bool RenderAttrib::
has_cull_callback() const {
  return false;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::cull_callback
//       Access: Public, Virtual
//  Description: If has_cull_callback() returns true, this function
//               will be called during the cull traversal to perform
//               any additional operations that should be performed at
//               cull time.
//
//               This is called each time the RenderAttrib is
//               discovered applied to a Geom in the traversal.  It
//               should return true if the Geom is visible, false if
//               it should be omitted.
////////////////////////////////////////////////////////////////////
bool RenderAttrib::
cull_callback(CullTraverser *, const CullTraverserData &) const {
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::get_auto_shader_attrib_impl
//       Access: Protected, Virtual
//  Description: 
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) RenderAttrib::
get_auto_shader_attrib_impl(const RenderState *state) const {
  return NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::unref
//       Access: Published, Virtual
//  Description: This method overrides ReferenceCount::unref() to
//               clear the pointer from the global object pool when
//               its reference count goes to zero.
////////////////////////////////////////////////////////////////////
bool RenderAttrib::
unref() const {
  if (!state_cache || garbage_collect_states) {
    // If we're not using the cache at all, or if we're relying on
    // garbage collection, just allow the pointer to unref normally.
    return ReferenceCount::unref();
  }

  // Here is the normal refcounting case, with a normal cache, and
  // without garbage collection in effect.  In this case we will pull
  // the object out of the cache when its reference count goes to 0.

  // We always have to grab the lock, since we will definitely need to
  // be holding it if we happen to drop the reference count to 0.
  // Having to grab the lock at every call to unref() is a big
  // limiting factor on parallelization.
  LightReMutexHolder holder(*_attribs_lock);

  if (ReferenceCount::unref()) {
    // The reference count is still nonzero.
    return true;
  }

  // The reference count has just reached zero.  Make sure the object
  // is removed from the global object pool, before anyone else finds
  // it and tries to ref it.
  ((RenderAttrib *)this)->release_new();

  return false;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::output
//       Access: Published, Virtual
//  Description: 
////////////////////////////////////////////////////////////////////
void RenderAttrib::
output(ostream &out) const {
  out << get_type();
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::write
//       Access: Published, Virtual
//  Description: 
////////////////////////////////////////////////////////////////////
void RenderAttrib::
write(ostream &out, int indent_level) const {
  indent(out, indent_level) << *this << "\n";
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::get_num_attribs
//       Access: Published, Static
//  Description: Returns the total number of unique RenderAttrib
//               objects allocated in the world.  This will go up and
//               down during normal operations.
////////////////////////////////////////////////////////////////////
int RenderAttrib::
get_num_attribs() {
  LightReMutexHolder holder(*_attribs_lock);

  if (_attribs == (Attribs *)NULL) {
    return 0;
  }
  return _attribs->get_num_entries();
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::list_attribs
//       Access: Published, Static
//  Description: Lists all of the RenderAttribs in the cache to the
//               output stream, one per line.  This can be quite a lot
//               of output if the cache is large, so be prepared.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
list_attribs(ostream &out) {
  LightReMutexHolder holder(*_attribs_lock);

  out << _attribs->get_num_entries() << " attribs:\n";
  int size = _attribs->get_size();
  for (int si = 0; si < size; ++si) {
    if (!_attribs->has_element(si)) {
      continue;
    }
    const RenderAttrib *attrib = _attribs->get_key(si);
    attrib->write(out, 2);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::garbage_collect
//       Access: Published, Static
//  Description: Performs a garbage-collection cycle.  This is called
//               automatically from RenderState::garbage_collect();
//               see that method for more information.
////////////////////////////////////////////////////////////////////
int RenderAttrib::
garbage_collect() {
  if (_attribs == (Attribs *)NULL || !garbage_collect_states) {
    return 0;
  }
  LightReMutexHolder holder(*_attribs_lock);

  PStatTimer timer(_garbage_collect_pcollector);
  int orig_size = _attribs->get_num_entries();

  nassertr(_attribs->validate(), 0);

  // How many elements to process this pass?
  int size = _attribs->get_size();
  int num_this_pass = int(size * garbage_collect_states_rate);
  if (num_this_pass <= 0) {
    return 0;
  }
  num_this_pass = min(num_this_pass, size);
  int stop_at_element = (_garbage_index + num_this_pass) % size;
  
  int num_elements = 0;
  int si = _garbage_index;
  do {
    if (_attribs->has_element(si)) {
      ++num_elements;
      RenderAttrib *attrib = (RenderAttrib *)_attribs->get_key(si);
      if (attrib->get_ref_count() == 1) {
        // This attrib has recently been unreffed to 1 (the one we
        // added when we stored it in the cache).  Now it's time to
        // delete it.  This is safe, because we're holding the
        // _attribs_lock, so it's not possible for some other thread to
        // find the attrib in the cache and ref it while we're doing
        // this.
        attrib->release_new();
        unref_delete(attrib);
      }
    }      

    si = (si + 1) % size;
  } while (si != stop_at_element);
  _garbage_index = si;
  nassertr(_attribs->validate(), 0);

  int new_size = _attribs->get_num_entries();
  return orig_size - new_size;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::validate_attribs
//       Access: Published, Static
//  Description: Ensures that the cache is still stored in sorted
//               order.  Returns true if so, false if there is a
//               problem (which implies someone has modified one of
//               the supposedly-const RenderAttrib objects).
////////////////////////////////////////////////////////////////////
bool RenderAttrib::
validate_attribs() {
  LightReMutexHolder holder(*_attribs_lock);
  if (_attribs->is_empty()) {
    return true;
  }

  if (!_attribs->validate()) {
    pgraph_cat.error()
      << "RenderAttrib::_attribs cache is invalid!\n";

    int size = _attribs->get_size();
    for (int si = 0; si < size; ++si) {
      if (!_attribs->has_element(si)) {
        continue;
      }
      const RenderAttrib *attrib = _attribs->get_key(si);
      cerr << si << ": " << attrib << "\n";
      attrib->get_hash();
      attrib->write(cerr, 2);
    }

    return false;
  }    

  int size = _attribs->get_size();
  int si = 0;
  while (si < size && !_attribs->has_element(si)) {
    ++si;
  }
  nassertr(si < size, false);
  nassertr(_attribs->get_key(si)->get_ref_count() >= 0, false);
  int snext = si;
  ++snext;
  while (snext < size && !_attribs->has_element(snext)) {
    ++snext;
  }
  while (snext < size) {
    nassertr(_attribs->get_key(snext)->get_ref_count() >= 0, false);
    const RenderAttrib *ssi = _attribs->get_key(si);
    const RenderAttrib *ssnext = _attribs->get_key(snext);
    int c = ssi->compare_to(*ssnext);
    int ci = ssnext->compare_to(*ssi);
    if ((ci < 0) != (c > 0) ||
        (ci > 0) != (c < 0) ||
        (ci == 0) != (c == 0)) {
      pgraph_cat.error()
        << "RenderAttrib::compare_to() not defined properly!\n";
      pgraph_cat.error(false)
        << "(a, b): " << c << "\n";
      pgraph_cat.error(false)
        << "(b, a): " << ci << "\n";
      ssi->write(pgraph_cat.error(false), 2);
      ssnext->write(pgraph_cat.error(false), 2);
      return false;
    }
    si = snext;
    ++snext;
    while (snext < size && !_attribs->has_element(snext)) {
      ++snext;
    }
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::return_new
//       Access: Protected, Static
//  Description: This function is used by derived RenderAttrib types
//               to share a common RenderAttrib pointer for all
//               equivalent RenderAttrib objects.
//
//               This is different from return_unique() in that it
//               does not actually guarantee a unique pointer, unless
//               uniquify-attribs is set.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) RenderAttrib::
return_new(RenderAttrib *attrib) {
  nassertr(attrib != (RenderAttrib *)NULL, attrib);
  if (!uniquify_attribs) {
    return attrib;
  }

  return return_unique(attrib);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::return_unique
//       Access: Protected, Static
//  Description: This function is used by derived RenderAttrib types
//               to share a common RenderAttrib pointer for all
//               equivalent RenderAttrib objects.
//
//               The make() function of the derived type should create
//               a new RenderAttrib and pass it through return_new(),
//               which will either save the pointer and return it
//               unchanged (if this is the first similar such object)
//               or delete it and return an equivalent pointer (if
//               there was already a similar object saved).
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) RenderAttrib::
return_unique(RenderAttrib *attrib) {
  nassertr(attrib != (RenderAttrib *)NULL, attrib);

  if (!state_cache) {
    return attrib;
  }

#ifndef NDEBUG
  if (paranoid_const) {
    nassertr(validate_attribs(), attrib);
  }
#endif

  LightReMutexHolder holder(*_attribs_lock);

  if (attrib->_saved_entry != -1) {
    // This attrib is already in the cache.
    //nassertr(_attribs->find(attrib) == attrib->_saved_entry, attrib);
    return attrib;
  }

  // Save the attrib in a local PointerTo so that it will be freed at
  // the end of this function if no one else uses it.
  CPT(RenderAttrib) pt_attrib = attrib;

  int si = _attribs->find(attrib);
  if (si != -1) {
    // There's an equivalent attrib already in the set.  Return it.
    return _attribs->get_key(si);
  }
  
  // Not already in the set; add it.
  if (garbage_collect_states) {
    // If we'll be garbage collecting attribs explicitly, we'll
    // increment the reference count when we store it in the cache, so
    // that it won't be deleted while it's in it.
    attrib->ref();
  }
  si = _attribs->store(attrib, Empty());

  // Save the index and return the input attrib.
  attrib->_saved_entry = si;
  return pt_attrib;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::compare_to_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to return a unique number indicating whether
//               this RenderAttrib is equivalent to the other one.
//
//               This should return 0 if the two RenderAttrib objects
//               are equivalent, a number less than zero if this one
//               should be sorted before the other one, and a number
//               greater than zero otherwise.
//
//               This will only be called with two RenderAttrib
//               objects whose get_type() functions return the same.
////////////////////////////////////////////////////////////////////
int RenderAttrib::
compare_to_impl(const RenderAttrib *other) const {
  return 0;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::get_hash_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to return a unique hash for these particular
//               properties.  RenderAttribs that compare the same with
//               compare_to_impl(), above, should return the same
//               hash; RenderAttribs that compare differently should
//               return a different hash.
////////////////////////////////////////////////////////////////////
size_t RenderAttrib::
get_hash_impl() const {
  return 0;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::compose_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               This should return the result of applying the other
//               RenderAttrib to a node in the scene graph below this
//               RenderAttrib, which was already applied.  In most
//               cases, the result is the same as the other
//               RenderAttrib (that is, a subsequent RenderAttrib
//               completely replaces the preceding one).  On the other
//               hand, some kinds of RenderAttrib (for instance,
//               ColorTransformAttrib) might combine in meaningful
//               ways.
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) RenderAttrib::
compose_impl(const RenderAttrib *other) const {
  return other;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::invert_compose_impl
//       Access: Protected, Virtual
//  Description: Intended to be overridden by derived RenderAttrib
//               types to specify how two consecutive RenderAttrib
//               objects of the same type interact.
//
//               See invert_compose() and compose_impl().
////////////////////////////////////////////////////////////////////
CPT(RenderAttrib) RenderAttrib::
invert_compose_impl(const RenderAttrib *other) const {
  return other;
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::output_comparefunc
//       Access: Protected
//  Description: Outputs a string representation of the given
//               PandaCompareFunc object.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
output_comparefunc(ostream &out, PandaCompareFunc fn) const {
  switch (fn) {
  case M_none:
    out << "none";
    break;

  case M_never:
    out << "never";
    break;

  case M_less:
    out << "less";
    break;

  case M_equal:
    out << "equal";
    break;

  case M_less_equal:
    out << "less_equal";
    break;

  case M_greater:
    out << "greater";
    break;

  case M_not_equal:
    out << "not_equal";
    break;

  case M_greater_equal:
    out << "greater_equal";
    break;

  case M_always:
    out << "always";
    break;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::release_new
//       Access: Private
//  Description: This inverse of return_new, this releases this object
//               from the global RenderAttrib table.
//
//               You must already be holding _attribs_lock before you
//               call this method.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
release_new() {
  nassertv(_attribs_lock->debug_is_locked());

  if (_saved_entry != -1) {
    //nassertv(_attribs->find(this) == _saved_entry);
    _saved_entry = _attribs->find(this);
    _attribs->remove_element(_saved_entry);
    _saved_entry = -1;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::init_attribs
//       Access: Public, Static
//  Description: Make sure the global _attribs map is allocated.  This
//               only has to be done once.  We could make this map
//               static, but then we run into problems if anyone
//               creates a RenderAttrib object at static init time;
//               it also seems to cause problems when the Panda shared
//               library is unloaded at application exit time.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
init_attribs() {
  _attribs = new Attribs;

  // TODO: we should have a global Panda mutex to allow us to safely
  // create _attribs_lock without a startup race condition.  For the
  // meantime, this is OK because we guarantee that this method is
  // called at static init time, presumably when there is still only
  // one thread in the world.
  _attribs_lock = new LightReMutex("RenderAttrib::_attribs_lock");
  nassertv(Thread::get_current_thread() == Thread::get_main_thread());
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::write_datagram
//       Access: Public, Virtual
//  Description: Writes the contents of this object to the datagram
//               for shipping out to a Bam file.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
write_datagram(BamWriter *manager, Datagram &dg) {
  TypedWritable::write_datagram(manager, dg);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::change_this
//       Access: Public, Static
//  Description: Called immediately after complete_pointers(), this
//               gives the object a chance to adjust its own pointer
//               if desired.  Most objects don't change pointers after
//               completion, but some need to.
//
//               Once this function has been called, the old pointer
//               will no longer be accessed.
////////////////////////////////////////////////////////////////////
TypedWritable *RenderAttrib::
change_this(TypedWritable *old_ptr, BamReader *manager) {
  // First, uniquify the pointer.
  RenderAttrib *attrib = DCAST(RenderAttrib, old_ptr);
  CPT(RenderAttrib) pointer = return_unique(attrib);

  // But now we have a problem, since we have to hold the reference
  // count and there's no way to return a TypedWritable while still
  // holding the reference count!  We work around this by explicitly
  // upping the count, and also setting a finalize() callback to down
  // it later.
  if (pointer == attrib) {
    pointer->ref();
    manager->register_finalize(attrib);
  }
  
  // We have to cast the pointer back to non-const, because the bam
  // reader expects that.
  return (RenderAttrib *)pointer.p();
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::finalize
//       Access: Public, Virtual
//  Description: Called by the BamReader to perform any final actions
//               needed for setting up the object after all objects
//               have been read and all pointers have been completed.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
finalize(BamReader *) {
  // Unref the pointer that we explicitly reffed in change_this().
  unref();

  // We should never get back to zero after unreffing our own count,
  // because we expect to have been stored in a pointer somewhere.  If
  // we do get to zero, it's a memory leak; the way to avoid this is
  // to call unref_delete() above instead of unref(), but this is
  // dangerous to do from within a virtual function.
  nassertv(get_ref_count() != 0);
}

////////////////////////////////////////////////////////////////////
//     Function: RenderAttrib::fillin
//       Access: Protected
//  Description: This internal function is called by make_from_bam to
//               read in all of the relevant data from the BamFile for
//               the new RenderAttrib.
////////////////////////////////////////////////////////////////////
void RenderAttrib::
fillin(DatagramIterator &scan, BamReader *manager) {
  TypedWritable::fillin(scan, manager);
  manager->register_change_this(change_this, this);
}
