From 2619106044aaf761b4040562c5af86e5f29ae935 Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Thu, 1 Aug 2002 06:15:59 +0000
Subject: [PATCH] Fix tile cache resizing bug (which could lead to thrashing.)

---
 src/Scenery/newcache.cxx |  9 +++++----
 src/Scenery/tilemgr.cxx  | 20 ++++++++++++--------
 src/Scenery/tilemgr.hxx  |  1 -
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/src/Scenery/newcache.cxx b/src/Scenery/newcache.cxx
index 9e1040d3d..f9c46b20a 100644
--- a/src/Scenery/newcache.cxx
+++ b/src/Scenery/newcache.cxx
@@ -175,7 +175,7 @@ bool FGNewCache::make_space() {
 // nothing available to be removed.
 long FGNewCache::get_oldest_tile() {
     // we need to free the furthest entry
-    long max_index = -1;
+    long min_index = -1;
     double timestamp = 0.0;
     double min_time = 2419200000.0f; // one month should be enough
     double max_time = 0;
@@ -190,7 +190,7 @@ long FGNewCache::get_oldest_tile() {
             
             timestamp = e->get_timestamp();
             if ( timestamp < min_time ) {
-                max_index = index;
+                min_index = index;
                 min_time = timestamp;
             }
             if ( timestamp > max_time ) {
@@ -205,10 +205,10 @@ long FGNewCache::get_oldest_tile() {
     }
 
     SG_LOG( SG_TERRAIN, SG_INFO, "    min_time = " << min_time );
-    SG_LOG( SG_TERRAIN, SG_INFO, "    index = " << max_index );
+    SG_LOG( SG_TERRAIN, SG_INFO, "    index = " << min_index );
     SG_LOG( SG_TERRAIN, SG_INFO, "    max_time = " << max_time );
 
-    return max_index;
+    return min_index;
 }
 
 
@@ -260,6 +260,7 @@ bool FGNewCache::insert_tile( FGTileEntry *e ) {
     }
 }
 
+
 // Note this is the old version of FGNewCache::make_space(), currently disabled
 // It uses distance from a center point to determine tiles to be discarded...
 #if 0
diff --git a/src/Scenery/tilemgr.cxx b/src/Scenery/tilemgr.cxx
index c9b335249..767fcd8e5 100644
--- a/src/Scenery/tilemgr.cxx
+++ b/src/Scenery/tilemgr.cxx
@@ -70,7 +70,6 @@ FGTileMgr::FGTileMgr():
     state( Start ),
     current_tile( NULL ),
     vis( 16000 ),
-    max_cache_size(100),
     counter_hack(0)
 {
 }
@@ -131,7 +130,7 @@ void FGTileMgr::sched_tile( const SGBucket& b ) {
 
     if ( t == NULL ) {
         // make space in the cache
-        while ( (int)tile_cache.get_size() > max_cache_size ) {
+        while ( (int)tile_cache.get_size() > tile_cache.get_max_cache_size() ) {
             long index = tile_cache.get_oldest_tile();
             if ( index >= 0 ) {
                 FGTileEntry *old = tile_cache.get_tile( index );
@@ -173,10 +172,10 @@ void FGTileMgr::schedule_needed( double vis, SGBucket curr_bucket) {
         exit(-1);        
     }
 
-   SG_LOG( SG_TERRAIN, SG_INFO,
-           "scheduling needed tiles for " << longitude << " " << latitude );
+    SG_LOG( SG_TERRAIN, SG_INFO,
+            "scheduling needed tiles for " << longitude << " " << latitude );
 
-//   vis = fgGetDouble("/environment/visibility-m");
+    // vis = fgGetDouble("/environment/visibility-m");
 
     double tile_width = curr_bucket.get_width_m();
     double tile_height = curr_bucket.get_height_m();
@@ -185,12 +184,17 @@ void FGTileMgr::schedule_needed( double vis, SGBucket curr_bucket) {
 
     xrange = (int)(vis / tile_width) + 1;
     yrange = (int)(vis / tile_height) + 1;
-    if ( xrange < 1 ) { xrange = 1; }
+    if ( xrange < 1 ) { xrange /= 1; }
     if ( yrange < 1 ) { yrange = 1; }
-    // cout << "xrange = " << xrange << "  yrange = " << yrange << endl;
 
     // note * 2 at end doubles cache size (for fdm and viewer)
-    max_cache_size = (2*xrange + 2) * (2*yrange + 2) * 2;
+    tile_cache.set_max_cache_size( (2*xrange + 2) * (2*yrange + 2) * 2 );
+
+    /*
+    cout << "xrange = " << xrange << "  yrange = " << yrange << endl;
+    cout << "max cache size = " << tile_cache.get_max_cache_size()
+         << " current cache size = " << tile_cache.get_size() << endl;
+    */
 
     SGBucket b;
 
diff --git a/src/Scenery/tilemgr.hxx b/src/Scenery/tilemgr.hxx
index 714bafa76..d268d4a86 100644
--- a/src/Scenery/tilemgr.hxx
+++ b/src/Scenery/tilemgr.hxx
@@ -105,7 +105,6 @@ private:
     /**
      * tile cache
      */
-    int max_cache_size;
     FGNewCache tile_cache;
 
     /**
-- 
2.39.5