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2022-10-20 20:29:11 +08:00
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src/Scenery/tilecache.cxx
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// TileCache.cxx -- routines to handle scenery tile caching
//
// Written by Curtis Olson, started December 2000.
//
// Copyright (C) 2000 Curtis L. Olson - http://www.flightgear.org/~curt
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <simgear/bucket/newbucket.hxx>
#include <simgear/debug/logstream.hxx>
#include <simgear/misc/sg_path.hxx>
#include "tileentry.hxx"
#include "tilecache.hxx"
TileCache::TileCache( void ) :
max_cache_size(100), current_time(0.0)
{
tile_cache.clear();
}
TileCache::~TileCache( void )
{
tile_map_iterator it = tile_cache.begin();
for (; it != tile_cache.end(); ++it) {
TileEntry* tile = it->second;
tile->removeFromSceneGraph();
delete tile;
}
}
// Free a tile cache entry
void TileCache::entry_free( long tile_index ) {
SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING CACHE ENTRY = " << tile_index );
TileEntry *tile = tile_cache[tile_index];
tile->removeFromSceneGraph();
tile_cache.erase( tile_index );
delete tile;
}
// Initialize the tile cache subsystem
void TileCache::init( void ) {
SG_LOG( SG_TERRAIN, SG_INFO, "Initializing the tile cache." );
SG_LOG( SG_TERRAIN, SG_INFO, " max cache size = "
<< max_cache_size );
SG_LOG( SG_TERRAIN, SG_INFO, " current cache size = "
<< tile_cache.size() );
clear_cache();
SG_LOG( SG_TERRAIN, SG_INFO, " done with init()" );
}
// Search for the specified "bucket" in the cache
bool TileCache::exists_stg( const SGBucket& b ) const {
long tile_index = b.gen_index();
const_tile_map_iterator it = tile_cache.find( tile_index );
return ( it != tile_cache.end() );
}
bool TileCache::exists_vpb( const SGBucket& b ) const {
// VPB tiles are stored with negative index to avoid clash with STG index
long tile_index = - b.gen_vpb_index();
const_tile_map_iterator it = tile_cache.find( tile_index );
return ( it != tile_cache.end() );
}
// Return the index of a tile to be dropped from the cache, return -1 if
// nothing available to be removed.
long TileCache::get_drop_tile() {
long min_index = -1;
double min_time = DBL_MAX;
float priority = FLT_MAX;
tile_map_iterator current = tile_cache.begin();
tile_map_iterator end = tile_cache.end();
for ( ; current != end; ++current ) {
long index = current->first;
TileEntry *e = current->second;
if (( !e->is_current_view() )&&
( e->is_expired(current_time) ))
{
if (e->is_expired(current_time - 1.0)&&
!e->is_loaded())
{
/* Immediately drop "empty" tiles which are no longer used/requested, and were last requested > 1 second ago...
* Allow a 1 second timeout since an empty tiles may just be loaded...
*/
SG_LOG( SG_TERRAIN, SG_DEBUG, " dropping an unused and empty tile");
min_index = index;
break;
}
if (( e->get_time_expired() < min_time )||
(( e->get_time_expired() == min_time)&&
( priority > e->get_priority())))
{
// drop oldest tile with lowest priority
min_time = e->get_time_expired();
priority = e->get_priority();
min_index = index;
}
}
}
SG_LOG( SG_TERRAIN, SG_DEBUG, " index = " << min_index );
SG_LOG( SG_TERRAIN, SG_DEBUG, " min_time = " << min_time );
return min_index;
}
long TileCache::get_first_expired_tile() const
{
const_tile_map_iterator current = tile_cache.begin();
const_tile_map_iterator end = tile_cache.end();
for ( ; current != end; ++current ) {
TileEntry *e = current->second;
if (!e->is_current_view() && e->is_expired(current_time))
{
return current->first;
}
}
return -1; // no expired tile found
}
// Clear all flags indicating tiles belonging to the current view
void TileCache::clear_current_view()
{
tile_map_iterator current = tile_cache.begin();
tile_map_iterator end = tile_cache.end();
for ( ; current != end; ++current ) {
TileEntry *e = current->second;
if (e->is_current_view())
{
// update expiry time for tiles belonging to most recent position
e->update_time_expired( current_time );
e->set_current_view( false );
}
}
}
// Clear a cache entry, note that the cache only holds pointers
// and this does not free the object which is pointed to.
void TileCache::clear_entry( long tile_index ) {
tile_cache.erase( tile_index );
}
// Clear all completely loaded tiles (ignores partially loaded tiles)
void TileCache::clear_cache() {
std::vector<long> indexList;
tile_map_iterator current = tile_cache.begin();
tile_map_iterator end = tile_cache.end();
for ( ; current != end; ++current ) {
long index = current->first;
TileEntry *e = current->second;
if ( e->is_loaded() ) {
e->tile_bucket.make_bad();
// entry_free modifies tile_cache, so store index and call entry_free() later;
indexList.push_back( index);
}
}
for (unsigned int it = 0; it < indexList.size(); it++) {
entry_free( indexList[ it]);
}
}
/**
* Create a new tile and schedule it for loading.
*/
bool TileCache::insert_tile( STGTileEntry *e ) {
// register tile in the cache
long tile_index = e->get_tile_bucket().gen_index();
tile_cache[tile_index] = e;
e->update_time_expired(current_time);
return true;
}
/**
* Create a new tile and schedule it for loading. VPB version, with negative index.
*/
bool TileCache::insert_tile( VPBTileEntry *e ) {
// register tile in the cache
long tile_index = - e->get_tile_bucket().gen_vpb_index();
tile_cache[tile_index] = e;
e->update_time_expired(current_time);
return true;
}
// update tile's priority and expiry time according to current request
void TileCache::request_tile(TileEntry* t,float priority,bool current_view,double request_time)
{
if ((!current_view)&&(request_time<=0.0))
return;
// update priority when higher - or old request has expired
if ((t->is_expired(current_time))||
(priority > t->get_priority()))
{
t->set_priority( priority );
}
if (current_view)
{
t->update_time_expired( current_time + request_time );
t->set_current_view( true );
}
else
{
t->update_time_expired( current_time+request_time );
}
}
// Return a pointer to the specified tile cache entry
STGTileEntry* TileCache::get_stg_tile( const SGBucket& b ) const {
const_tile_map_iterator it = std::find_if(tile_cache.begin(), tile_cache.end(),
[b](auto &t) {
return ((b.gen_index() == t.first) && (t.second->getExtension() == TileEntry::Extension::STG));
});
if ( it != tile_cache.end() ) {
return dynamic_cast<STGTileEntry*>(it->second);
} else {
return NULL;
}
}
// Return a pointer to the specified tile cache entry
VPBTileEntry* TileCache::get_vpb_tile( const SGBucket& b ) const {
const_tile_map_iterator it = std::find_if(tile_cache.begin(), tile_cache.end(),
[b](auto &t) {
// Negative indices are used for the VPB tiles.
return (( - b.gen_vpb_index() == t.first) && (t.second->getExtension() == TileEntry::Extension::VPB));
});
if ( it != tile_cache.end() ) {
return dynamic_cast<VPBTileEntry*>(it->second);
} else {
return NULL;
}
}