buffer-provider.cpp

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/*
  BufferProvider  -  Abstraction for Buffer management during playback/render

  Copyright (C)         Lumiera.org
    2008,               Hermann Vosseler <Ichthyostega@web.de>

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of
  the License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

* *****************************************************/


#include "lib/error.hpp"
#include "steam/engine/buffer-provider.hpp"
#include "steam/engine/buffer-metadata.hpp"
#include "lib/util.hpp"

using util::isSameObject;

namespace steam {
namespace engine {
  
  
  namespace { // impl. details and definitions
    
    const uint DEFAULT_DESCRIPTOR = 0;
    
  }
  
  LUMIERA_ERROR_DEFINE (BUFFER_MANAGEMENT, "Problem providing working buffers");
  
  
  BufferProvider::BufferProvider (Literal implementationID)
    : meta_(new BufferMetadata (implementationID))
    { }
  
  BufferProvider::~BufferProvider() { }
  
  
  bool
  BufferProvider::verifyValidity (BufferDescriptor const& bufferID)  const
  {
    return meta_->isLocked (bufferID);
  }
  
  
  BufferDescriptor
  BufferProvider::getDescriptorFor (size_t storageSize)
  {
    return BufferDescriptor (*this, meta_->key (storageSize));
  }
  
  
  BufferDescriptor
  BufferProvider::getDescriptorFor(size_t storageSize, TypeHandler specialTreatment)
  {
    return BufferDescriptor (*this, meta_->key (storageSize, specialTreatment));
  }
  
  
  size_t
  BufferProvider::getBufferSize (HashVal typeID)  const
  {
    metadata::Key& typeKey = meta_->get (typeID);
    return typeKey.storageSize();
  }
  
  
  BuffHandle
  BufferProvider::buildHandle (HashVal typeID, void* storage, LocalKey const& implID)
  {
    metadata::Key& typeKey = meta_->get (typeID);
    metadata::Entry& entry = meta_->markLocked(typeKey, storage, implID);
    
    return BuffHandle (BufferDescriptor(*this, entry), storage);
  }
  
  
  uint
  BufferProvider::announce (uint count, BufferDescriptor const& type)
  {
    uint actually_possible = prepareBuffers (count, type);
    if (!actually_possible)
      throw error::State ("unable to fulfil request for buffers"
                         ,LUMIERA_ERROR_BUFFER_MANAGEMENT);
    return actually_possible;
  }
  
  
  BuffHandle
  BufferProvider::lockBuffer (BufferDescriptor const& type)
  {
    REQUIRE (was_created_by_this_provider (type));
    
    return provideLockedBuffer (type);
  }     // is expected to call buildHandle() --> state transition
  
  
  void
  BufferProvider::emitBuffer (BuffHandle const& handle)
  {
    metadata::Entry& metaEntry = meta_->get (handle.entryID());
    mark_emitted (metaEntry.parentKey(), metaEntry.localKey());
    metaEntry.mark(EMITTED);
  }
  
  
  void
  BufferProvider::releaseBuffer (BuffHandle const& handle)
  try {
    metadata::Entry& metaEntry = meta_->get (handle.entryID());
    metaEntry.mark(FREE);   // might invoke embedded dtor function
    detachBuffer (metaEntry.parentKey(), metaEntry.localKey());
    meta_->release (metaEntry);
  }
  ERROR_LOG_AND_IGNORE (engine, "releasing a buffer from BufferProvider")
  
  
  
  
  void
  BufferProvider::attachTypeHandler (BuffHandle const& target, BufferDescriptor const& reference)
  {
    metadata::Entry& metaEntry = meta_->get (target.entryID());
    metadata::Entry& refEntry = meta_->get (reference);
    REQUIRE (refEntry.isTypeKey());
    REQUIRE (!metaEntry.isTypeKey());
    if (!metaEntry.isLocked())
      throw error::Logic{"unable to attach an object because buffer isn't locked for use"
                        , LERR_(LIFECYCLE)};
    
    metaEntry.useTypeHandlerFrom (refEntry); // EX_STRONG
  }
  
  
  void
  BufferProvider::emergencyCleanup (BuffHandle const& target, bool invokeDtor)
  try {
    metadata::Entry& metaEntry = meta_->get (target.entryID());
    metaEntry.invalidate (invokeDtor);
    detachBuffer (metaEntry.parentKey(), metaEntry.localKey());
    meta_->release (metaEntry);
  }
  ERROR_LOG_AND_IGNORE (engine, "cleanup of buffer metadata while handling an error")
  
  
  
  bool
  BufferProvider::was_created_by_this_provider (BufferDescriptor const& descr)  const
  {
    return isSameObject (*this, *descr.provider_);
  }
  
  
  
  
  
  /* === BufferDescriptor and BuffHandle === */
  
  bool
  BufferDescriptor::verifyValidity()  const
  {
    return provider_->verifyValidity(*this);
  }
  
  
  size_t
  BufferDescriptor::determineBufferSize() const
  {
    return provider_->getBufferSize (*this);
  }
  
  
  void
  BuffHandle::emit()
  {
    REQUIRE (isValid());
    descriptor_.provider_->emitBuffer(*this);
  }
  
  
  void
  BuffHandle::release()
  {
    if (pBuffer_)
      {
        REQUIRE (isValid());
        descriptor_.provider_->releaseBuffer(*this);
        pBuffer_ = 0;
      }
    ENSURE (!isValid());
  }
  
  
  void
  BuffHandle::emergencyCleanup()
  {
    descriptor_.provider_->emergencyCleanup(*this); // EX_FREE
    pBuffer_ = 0;
  }
  
  
  void
  BuffHandle::takeOwnershipFor(BufferDescriptor const& type)
  {
    if (!this->isValid())
      throw error::Logic ("attaching an object requires an buffer in locked state", LERR_(LIFECYCLE));
    if (this->size() < type.determineBufferSize())
      throw error::Logic ("insufficient buffer size to hold an instance of that type");
    
    descriptor_.provider_->attachTypeHandler(*this, type); // EX_STRONG
  }
  
  
  
  
}} // namespace engine