From b9771b85d4f543af78465985e6350c0ca57f4c70 Mon Sep 17 00:00:00 2001
From: Stefan Zabka <zabkaste@hu-berlin.de>
Date: Thu, 11 Jun 2020 23:24:02 +0200
Subject: Broken Mess

---
 04_exercise/arena/arena_list.h | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

(limited to '04_exercise/arena/arena_list.h')

diff --git a/04_exercise/arena/arena_list.h b/04_exercise/arena/arena_list.h
index 387f881..304209c 100644
--- a/04_exercise/arena/arena_list.h
+++ b/04_exercise/arena/arena_list.h
@@ -6,6 +6,9 @@
 #define BETRIEBSYSTEME_ARENA_LIST_H
 
 #include <stdlib.h>
+#include <stdbool.h>
+#include <stdatomic.h>
+
 typedef struct Node {
     void * value;
     struct Node * next;
@@ -16,24 +19,39 @@ typedef struct List {
     Node * first;
     Node * last;
 } List;
-// This structure manages an arena / memory slab to be used
+
+
 // Should we have a free list or just a bit set relative to the size of the slab?
+/** This structure manages an arena / memory slab to be used
+ * This structure is thread-safe as it locks internally
+ * It will spin until a request is safe to access the items
+ * This also means this structure shouldn't be read externally
+ * unless the thread doing so managed to aquire the atomic_flag
+ */
 typedef struct ArenaList {
     List freeList;
     List activeList;
     Node * arena;
     size_t size;
-} ArenaList;
+    atomic_char lock;
+} AtomicArenaList;
 
+typedef bool (*SearchFunction)(void const *);
 //Initializes the node array
-ArenaList alInit(Node * arena, size_t size);
+AtomicArenaList alInit(Node * arena, size_t size);
 // Return -1 if the List is full
-int alPush(ArenaList*  al, void * value);
+int alPush(AtomicArenaList *  al, void * value);
 
 // Return -1 if the Node was already deleted
-int alRemove(ArenaList*  al, Node * node);
+int alRemoveElem(AtomicArenaList *  al, void * value);
 
-// Return -1 if the Node was already deleted
-int alRemoveElem(ArenaList*  al, void * value);
+/**
+ * Searches the activeList for an element
+ * for which the search function returns true
+ * The function will be passed the value pointer
+ * of a given Node
+ * @return the Element pointed or NULL if nothing matched
+ */
+void *alFindLastElem(AtomicArenaList *al, SearchFunction f);
 
 #endif // BETRIEBSYSTEME_ARENA_LIST_H
-- 
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