planner: remove Bühlmann factor cache

The Bühlmann factors were cached in a thread-safe hashmap. It seemed
somewhat dubious that entering a critical section and doing a hash-lookup
would be significantly faster than a simple exp() call.

Indeed, in a very cache friendly test (16 entries, tight loop) calling the
factor() function 32 000 000 times from a different translation units we get:
  - with cache: 604 ms
  - without cache: 266 ms
Therefore, remove the cache. Given that 32 000 000 calls take only 266 ms,
it appears not sensible to try to optimize this function anyway.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 0 insertions, 25 deletions

diff --git a/core/qthelper.cpp b/core/qthelper.cpp
index bb68afcbc..e543ad1c1 100644
--- a/core/qthelper.cpp
+++ b/core/qthelper.cpp
@@ -1601,31 +1601,6 @@ char *intdup(int index)
 	return strdup(tmpbuf);
 }
 
-QHash<int, double> factor_cache;
-
-QReadWriteLock factorCacheLock;
-extern "C" double cache_value(int tissue, int timestep, enum inertgas inertgas)
-{
-	double value;
-	int key = (timestep << 5) + (tissue << 1);
-	if (inertgas == HE)
-		++key;
-	factorCacheLock.lockForRead();
-	value = factor_cache.value(key);
-	factorCacheLock.unlock();
-	return value;
-}
-
-extern "C" void cache_insert(int tissue, int timestep, enum inertgas inertgas, double value)
-{
-	int key = (timestep << 5) + (tissue << 1);
-	if (inertgas == HE)
-		++key;
-	factorCacheLock.lockForWrite();
-	factor_cache.insert(key, value);
-	factorCacheLock.unlock();
-}
-
 extern "C" void print_qt_versions()
 {
 	printf("%s\n", qPrintable(QStringLiteral("built with Qt Version %1, runtime from Qt Version %2").arg(QT_VERSION_STR).arg(qVersion())));