Change movie cache to use vectors instead of lists.

Runtime costs were horrible. On gooseberry in some sequencer edits using
proxies of small size, a cache with about 2000 elements would slow to
about 6 fps once cache was full and system tried to find smallest
element available.

There are still improvements to be done here, like requesting a number
of good candidates to avoid rerunnung through the list, or even using
some heap or ring buffer scheme to sort data, but nothing suits all
needs so for now that should bring the cache back to usable state (25fps
here at the studio)

intern/memutil/MEM_CacheLimiter.h

@@ -130,7 +130,7 @@ private:
 
 	T * data;
 	int refcount;
-	typename std::list<MEM_CacheLimiterHandle<T> *, MEM_Allocator<MEM_CacheLimiterHandle<T> *> >::iterator me;
+	int pos;
 	MEM_CacheLimiter<T> * parent;
 };
 
@@ -146,29 +146,32 @@ public:
 	}
 
 	~MEM_CacheLimiter() {
-		for (iterator it = queue.begin(); it != queue.end(); it++) {
-			delete *it;
+		int i;
+		for (i = 0; i < queue.size(); i++) {
+			delete queue[i];
 		}
 	}
 
 	MEM_CacheLimiterHandle<T> *insert(T * elem) {
 		queue.push_back(new MEM_CacheLimiterHandle<T>(elem, this));
-		iterator it = queue.end();
-		--it;
-		queue.back()->me = it;
+		queue.back()->pos = queue.size() - 1;
 		return queue.back();
 	}
 
 	void unmanage(MEM_CacheLimiterHandle<T> *handle) {
-		queue.erase(handle->me);
+		int pos = handle->pos;
+		queue[pos] = queue.back();
+		queue[pos]->pos = pos;
+		queue.pop_back();
 		delete handle;
 	}
 
 	size_t get_memory_in_use() {
 		size_t size = 0;
 		if (data_size_func) {
-			for (iterator it = queue.begin(); it != queue.end(); it++) {
-				size += data_size_func((*it)->get()->get_data());
+			int i;
+			for (i = 0; i < queue.size(); i++) {
+				size += data_size_func(queue[i]->get()->get_data());
 			}
 		}
 		else {
@@ -226,11 +229,11 @@ public:
 		 * least priority element anyway.
 		 */
 		if (item_priority_func == NULL) {
+			queue[handle->pos] = queue.back();
+			queue[handle->pos]->pos = handle->pos;
+			queue.pop_back();
 			queue.push_back(handle);
-			queue.erase(handle->me);
-			iterator it = queue.end();
-			--it;
-			handle->me = it;
+			handle->pos = queue.size() - 1;
 		}
 	}
 
@@ -244,7 +247,7 @@ public:
 
 private:
 	typedef MEM_CacheLimiterHandle<T> *MEM_CacheElementPtr;
-	typedef std::list<MEM_CacheElementPtr, MEM_Allocator<MEM_CacheElementPtr> > MEM_CacheQueue;
+	typedef std::vector<MEM_CacheElementPtr, MEM_Allocator<MEM_CacheElementPtr> > MEM_CacheQueue;
 	typedef typename MEM_CacheQueue::iterator iterator;
 
 	/* Check whether element can be destroyed when enforcing cache limits */
@@ -277,11 +280,10 @@ private:
 		}
 		else {
 			int best_match_priority = 0;
-			iterator it;
 			int i;
 
-			for (it = queue.begin(), i = 0; it != queue.end(); it++, i++) {
-				MEM_CacheElementPtr elem = *it;
+			for (i = 0; i < queue.size(); i++) {
+				MEM_CacheElementPtr elem = queue[i];
 
 				if (!can_destroy_element(elem))
 					continue;