//
// Created by stefan on 10.06.20.
//

#ifndef BETRIEBSYSTEME_ARENA_LIST_H
#define BETRIEBSYSTEME_ARENA_LIST_H

#include <stdlib.h>
#include <stdbool.h>
#include <stdatomic.h>

typedef struct Node {
    void * value;
    struct Node * next;
    struct Node * prev;
} Node;

typedef struct List {
    Node * first;
    Node * last;
} List;


// 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;
    atomic_char lock;
} AtomicArenaList;

typedef bool (*SearchFunction)(void const *);
//Initializes the node array
AtomicArenaList alInit(Node * arena, size_t size);
// Return -1 if the List is full
int alPush(AtomicArenaList *  al, void * value);

// Return -1 if the Node was already deleted
int alRemoveElem(AtomicArenaList *  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