From 1528b64a68f3144b9b321efefb22800a52e64dd4 Mon Sep 17 00:00:00 2001
From: rubidium <rubidium@openttd.org>
Date: Wed, 21 Oct 2009 19:38:50 +0000
Subject: (svn r17839) -Codechange: implement the concept of 'caching' pool
 items to pools, that is instead of 'free' push the unused items in a linked
 list and use them on 'malloc'. Also add the concept of zeroing, or actually
 not zeroing, on new for pool items.

---
 src/core/pool_func.hpp | 36 +++++++++++++++++++++++++++++++-----
 src/core/pool_type.hpp | 19 +++++++++++++++++--
 2 files changed, 48 insertions(+), 7 deletions(-)

(limited to 'src/core')

diff --git a/src/core/pool_func.hpp b/src/core/pool_func.hpp
index 567ef1ae9..68ee378b3 100644
--- a/src/core/pool_func.hpp
+++ b/src/core/pool_func.hpp
@@ -17,8 +17,8 @@
 #include "pool_type.hpp"
 
 #define DEFINE_POOL_METHOD(type) \
-	template <class Titem, typename Tindex, size_t Tgrowth_step, size_t Tmax_size> \
-	type Pool<Titem, Tindex, Tgrowth_step, Tmax_size>
+	template <class Titem, typename Tindex, size_t Tgrowth_step, size_t Tmax_size, bool Tcache, bool Tzero> \
+	type Pool<Titem, Tindex, Tgrowth_step, Tmax_size, Tcache, Tzero>
 
 DEFINE_POOL_METHOD(inline)::Pool(const char *name) :
 		name(name),
@@ -27,7 +27,8 @@ DEFINE_POOL_METHOD(inline)::Pool(const char *name) :
 		first_unused(0),
 		items(0),
 		cleaning(false),
-		data(NULL)
+		data(NULL),
+		alloc_cache(NULL)
 { }
 
 DEFINE_POOL_METHOD(inline void)::ResizeFor(size_t index)
@@ -75,7 +76,18 @@ DEFINE_POOL_METHOD(inline void *)::AllocateItem(size_t size, size_t index)
 	this->first_unused = max(this->first_unused, index + 1);
 	this->items++;
 
-	Titem *item = this->data[index] = (Titem *)CallocT<byte>(size);
+	Titem *item;
+	if (Tcache && this->alloc_cache != NULL) {
+		assert(sizeof(Titem) == size);
+		item = (Titem *)this->alloc_cache;
+		this->alloc_cache = this->alloc_cache->next;
+		if (Tzero) MemSetT(item, 0);
+	} else if (Tzero) {
+		item = (Titem *)CallocT<byte>(size);
+	} else {
+		item = (Titem *)MallocT<byte>(size);
+	}
+	this->data[index] = item;
 	item->index = (uint)index;
 	return item;
 }
@@ -111,7 +123,13 @@ DEFINE_POOL_METHOD(void)::FreeItem(size_t index)
 {
 	assert(index < this->size);
 	assert(this->data[index] != NULL);
-	free(this->data[index]);
+	if (Tcache) {
+		AllocCache *ac = (AllocCache *)this->data[index];
+		ac->next = this->alloc_cache;
+		this->alloc_cache = ac;
+	} else {
+		free(this->data[index]);
+	}
 	this->data[index] = NULL;
 	this->first_free = min(this->first_free, index);
 	this->items--;
@@ -129,6 +147,14 @@ DEFINE_POOL_METHOD(void)::CleanPool()
 	this->first_unused = this->first_free = this->size = 0;
 	this->data = NULL;
 	this->cleaning = false;
+
+	if (Tcache) {
+		while (this->alloc_cache != NULL) {
+			AllocCache *ac = this->alloc_cache;
+			this->alloc_cache = ac->next;
+			free(ac);
+		}
+	}
 }
 
 #undef DEFINE_POOL_METHOD
diff --git a/src/core/pool_type.hpp b/src/core/pool_type.hpp
index 728678515..58a58f6ac 100644
--- a/src/core/pool_type.hpp
+++ b/src/core/pool_type.hpp
@@ -18,8 +18,11 @@
  * @tparam Tindex       Type of the index for this pool
  * @tparam Tgrowth_step Size of growths; if the pool is full increase the size by this amount
  * @tparam Tmax_size    Maximum size of the pool
+ * @tparam Tcache       Whether to perform 'alloc' caching, i.e. don't actually free/malloc just reuse the memory
+ * @tparam Tzero        Whether to zero the memory
+ * @warning when Tcache is enabled *all* instances of this pool's item must be of the same size.
  */
-template <class Titem, typename Tindex, size_t Tgrowth_step, size_t Tmax_size>
+template <class Titem, typename Tindex, size_t Tgrowth_step, size_t Tmax_size, bool Tcache = false, bool Tzero = true>
 struct Pool {
 	static const size_t MAX_SIZE = Tmax_size; ///< Make template parameter accessible from outside
 
@@ -75,7 +78,7 @@ struct Pool {
 	 * Base class for all PoolItems
 	 * @tparam Tpool The pool this item is going to be part of
 	 */
-	template <struct Pool<Titem, Tindex, Tgrowth_step, Tmax_size> *Tpool>
+	template <struct Pool<Titem, Tindex, Tgrowth_step, Tmax_size, Tcache, Tzero> *Tpool>
 	struct PoolItem {
 		Tindex index; ///< Index of this pool item
 
@@ -252,6 +255,18 @@ struct Pool {
 private:
 	static const size_t NO_FREE_ITEM = MAX_UVALUE(size_t); ///< Contant to indicate we can't allocate any more items
 
+	/**
+	 * Helper struct to cache 'freed' PoolItems so we
+	 * do not need to allocate them again.
+	 */
+	struct AllocCache {
+		/** The next in our 'cache' */
+		AllocCache *next;
+	};
+
+	/** Cache of freed pointers */
+	AllocCache *alloc_cache;
+
 	/**
 	 * Makes given index valid
 	 * @param size size of item
-- 
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