1 // TileCache.cxx -- routines to handle scenery tile caching
3 // Written by Curtis Olson, started December 2000.
5 // Copyright (C) 2000 Curtis L. Olson - http://www.flightgear.org/~curt
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 #include <simgear/bucket/newbucket.hxx>
28 #include <simgear/debug/logstream.hxx>
29 #include <simgear/misc/sg_path.hxx>
31 #include "tileentry.hxx"
32 #include "tilecache.hxx"
34 TileCache::TileCache( void ) :
35 max_cache_size(100), current_time(0.0)
41 TileCache::~TileCache( void ) {
46 // Free a tile cache entry
47 void TileCache::entry_free( long tile_index ) {
48 SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING CACHE ENTRY = " << tile_index );
49 TileEntry *tile = tile_cache[tile_index];
50 tile->removeFromSceneGraph();
51 tile_cache.erase( tile_index );
56 // Initialize the tile cache subsystem
57 void TileCache::init( void ) {
58 SG_LOG( SG_TERRAIN, SG_INFO, "Initializing the tile cache." );
60 SG_LOG( SG_TERRAIN, SG_INFO, " max cache size = "
62 SG_LOG( SG_TERRAIN, SG_INFO, " current cache size = "
63 << tile_cache.size() );
67 SG_LOG( SG_TERRAIN, SG_INFO, " done with init()" );
71 // Search for the specified "bucket" in the cache
72 bool TileCache::exists( const SGBucket& b ) const {
73 long tile_index = b.gen_index();
74 const_tile_map_iterator it = tile_cache.find( tile_index );
76 return ( it != tile_cache.end() );
80 // Return the index of a tile to be dropped from the cache, return -1 if
81 // nothing available to be removed.
82 long TileCache::get_drop_tile() {
84 double min_time = DBL_MAX;
85 float priority = FLT_MAX;
87 tile_map_iterator current = tile_cache.begin();
88 tile_map_iterator end = tile_cache.end();
90 for ( ; current != end; ++current ) {
91 long index = current->first;
92 TileEntry *e = current->second;
93 if (( !e->is_current_view() )&&
94 ( e->is_expired(current_time) ))
96 if (e->is_expired(current_time - 1.0)&&
99 /* Immediately drop "empty" tiles which are no longer used/requested, and were last requested > 1 second ago...
100 * Allow a 1 second timeout since an empty tiles may just be loaded...
102 SG_LOG( SG_TERRAIN, SG_DEBUG, " dropping an unused and empty tile");
106 if (( e->get_time_expired() < min_time )||
107 (( e->get_time_expired() == min_time)&&
108 ( priority > e->get_priority())))
110 // drop oldest tile with lowest priority
111 min_time = e->get_time_expired();
112 priority = e->get_priority();
118 SG_LOG( SG_TERRAIN, SG_DEBUG, " index = " << min_index );
119 SG_LOG( SG_TERRAIN, SG_DEBUG, " min_time = " << min_time );
125 // Clear all flags indicating tiles belonging to the current view
126 void TileCache::clear_current_view()
128 tile_map_iterator current = tile_cache.begin();
129 tile_map_iterator end = tile_cache.end();
131 for ( ; current != end; ++current ) {
132 TileEntry *e = current->second;
133 if (e->is_current_view())
135 // update expiry time for tiles belonging to most recent position
136 e->update_time_expired( current_time );
137 e->set_current_view( false );
142 // Clear a cache entry, note that the cache only holds pointers
143 // and this does not free the object which is pointed to.
144 void TileCache::clear_entry( long tile_index ) {
145 tile_cache.erase( tile_index );
149 // Clear all completely loaded tiles (ignores partially loaded tiles)
150 void TileCache::clear_cache() {
151 std::vector<long> indexList;
152 tile_map_iterator current = tile_cache.begin();
153 tile_map_iterator end = tile_cache.end();
155 for ( ; current != end; ++current ) {
156 long index = current->first;
157 SG_LOG( SG_TERRAIN, SG_DEBUG, "clearing " << index );
158 TileEntry *e = current->second;
159 if ( e->is_loaded() ) {
160 e->tile_bucket.make_bad();
161 // entry_free modifies tile_cache, so store index and call entry_free() later;
162 indexList.push_back( index);
165 for (unsigned int it = 0; it < indexList.size(); it++) {
166 entry_free( indexList[ it]);
171 * Create a new tile and schedule it for loading.
173 bool TileCache::insert_tile( TileEntry *e ) {
174 // register tile in the cache
175 long tile_index = e->get_tile_bucket().gen_index();
176 tile_cache[tile_index] = e;
177 e->update_time_expired(current_time);
183 * Reloads a tile when it's already in memory.
185 void TileCache::refresh_tile(long tile_index)
187 const_tile_map_iterator it = tile_cache.find( tile_index );
188 if ( it == tile_cache.end() )
191 SG_LOG( SG_TERRAIN, SG_DEBUG, "REFRESHING CACHE ENTRY = " << tile_index );
194 it->second->refresh();
197 // update tile's priority and expiry time according to current request
198 void TileCache::request_tile(TileEntry* t,float priority,bool current_view,double request_time)
200 if ((!current_view)&&(request_time<=0.0))
203 // update priority when higher - or old request has expired
204 if ((t->is_expired(current_time))||
205 (priority > t->get_priority()))
207 t->set_priority( priority );
212 t->update_time_expired( current_time );
213 t->set_current_view( true );
217 t->update_time_expired( current_time+request_time );