0ad/source/lib/lockless.h

#include "posix_types.h"	// uintptr_t

// atomic "compare and swap". compare the machine word at <location> against
// <expected>; if not equal, return false; otherwise, overwrite it with
// <new_value> and return true.
extern bool CAS_(uintptr_t* location, uintptr_t expected, uintptr_t new_value);

#define CAS(l,o,n) CAS_((uintptr_t*)l, (uintptr_t)o, (uintptr_t)n)


//
// lock-free singly linked list
//

struct LFList
{
	void* head;
};

// make ready a previously unused(!) list object. if a negative error
// code (currently only ERR_NO_MEM) is returned, the list can't be used.
extern int lfl_init(LFList* list);

// call when list is no longer needed; should no longer hold any references.
extern void lfl_free(LFList* list);

// return pointer to "user data" attached to <key>,
// or 0 if not found in the list.
extern void* lfl_find(LFList* list, void* key);

// insert into list in order of increasing key. ensures items are unique
// by first checking if already in the list. returns 0 if out of memory,
// otherwise a pointer to "user data" attached to <key>. the optional
// <was_inserted> return variable indicates whether <key> was added.
extern void* lfl_insert(LFList* list, void* key, size_t additional_bytes, int* was_inserted);

// remove from list; return -1 if not found, or 0 on success.
extern int lfl_erase(LFList* list, void* key);