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.
24 # include <simgear_config.h>
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 using simgear::TileEntry;
35 using simgear::TileCache;
37 TileCache::TileCache( void ) :
38 max_cache_size(100), current_time(0.0)
44 TileCache::~TileCache( void ) {
49 // Free a tile cache entry
50 void TileCache::entry_free( long tile_index ) {
51 SG_LOG( SG_TERRAIN, SG_DEBUG, "FREEING CACHE ENTRY = " << tile_index );
52 TileEntry *tile = tile_cache[tile_index];
53 tile->removeFromSceneGraph();
54 tile_cache.erase( tile_index );
59 // Initialize the tile cache subsystem
60 void TileCache::init( void ) {
61 SG_LOG( SG_TERRAIN, SG_INFO, "Initializing the tile cache." );
63 SG_LOG( SG_TERRAIN, SG_INFO, " max cache size = "
65 SG_LOG( SG_TERRAIN, SG_INFO, " current cache size = "
66 << tile_cache.size() );
70 SG_LOG( SG_TERRAIN, SG_INFO, " done with init()" );
74 // Search for the specified "bucket" in the cache
75 bool TileCache::exists( const SGBucket& b ) const {
76 long tile_index = b.gen_index();
77 const_tile_map_iterator it = tile_cache.find( tile_index );
79 return ( it != tile_cache.end() );
83 // Return the index of a tile to be dropped from the cache, return -1 if
84 // nothing available to be removed.
85 long TileCache::get_drop_tile() {
87 double min_time = DBL_MAX;
88 float priority = FLT_MAX;
90 tile_map_iterator current = tile_cache.begin();
91 tile_map_iterator end = tile_cache.end();
93 for ( ; current != end; ++current ) {
94 long index = current->first;
95 TileEntry *e = current->second;
96 if (( !e->is_current_view() )&&
97 ( e->is_expired(current_time) ))
99 if (e->is_expired(current_time - 1.0)&&
102 /* Immediately drop "empty" tiles which are no longer used/requested, and were last requested > 1 second ago...
103 * Allow a 1 second timeout since an empty tiles may just be loaded...
105 SG_LOG( SG_TERRAIN, SG_DEBUG, " dropping an unused and empty tile");
108 if (( e->get_time_expired() < min_time )||
109 (( e->get_time_expired() == min_time)&&
110 ( priority > e->get_priority())))
112 // drop oldest tile with lowest priority
113 min_time = e->get_time_expired();
114 priority = e->get_priority();
120 SG_LOG( SG_TERRAIN, SG_DEBUG, " index = " << min_index );
121 SG_LOG( SG_TERRAIN, SG_DEBUG, " min_time = " << min_time );
127 // Clear all flags indicating tiles belonging to the current view
128 void TileCache::clear_current_view()
130 tile_map_iterator current = tile_cache.begin();
131 tile_map_iterator end = tile_cache.end();
133 for ( ; current != end; ++current ) {
134 TileEntry *e = current->second;
135 if (e->is_current_view())
137 // update expiry time for tiles belonging to most recent position
138 e->update_time_expired( current_time );
139 e->set_current_view( false );
144 // Clear a cache entry, note that the cache only holds pointers
145 // and this does not free the object which is pointed to.
146 void TileCache::clear_entry( long tile_index ) {
147 tile_cache.erase( tile_index );
151 // Clear all completely loaded tiles (ignores partially loaded tiles)
152 void TileCache::clear_cache() {
153 std::vector<long> indexList;
154 tile_map_iterator current = tile_cache.begin();
155 tile_map_iterator end = tile_cache.end();
157 for ( ; current != end; ++current ) {
158 long index = current->first;
159 SG_LOG( SG_TERRAIN, SG_DEBUG, "clearing " << index );
160 TileEntry *e = current->second;
161 if ( e->is_loaded() ) {
162 e->tile_bucket.make_bad();
163 // entry_free modifies tile_cache, so store index and call entry_free() later;
164 indexList.push_back( index);
167 for (unsigned int it = 0; it < indexList.size(); it++) {
168 entry_free( indexList[ it]);
173 * Create a new tile and schedule it for loading.
175 bool TileCache::insert_tile( TileEntry *e ) {
176 // register tile in the cache
177 long tile_index = e->get_tile_bucket().gen_index();
178 tile_cache[tile_index] = e;
179 e->update_time_expired(current_time);
185 * Reloads a tile when it's already in memory.
187 void TileCache::refresh_tile(long tile_index)
189 const_tile_map_iterator it = tile_cache.find( tile_index );
190 if ( it == tile_cache.end() )
193 SG_LOG( SG_TERRAIN, SG_DEBUG, "REFRESHING CACHE ENTRY = " << tile_index );
196 it->second->refresh();
199 // update tile's priority and expiry time according to current request
200 void TileCache::request_tile(TileEntry* t,float priority,bool current_view,double request_time)
202 if ((!current_view)&&(request_time<=0.0))
205 // update priority when higher - or old request has expired
206 if ((t->is_expired(current_time))||
207 (priority > t->get_priority()))
209 t->set_priority( priority );
214 t->update_time_expired( current_time );
215 t->set_current_view( true );
219 t->update_time_expired( current_time+request_time );