Skip to content
Permalink
Browse files
Add basic atomic operations for refcounting, etc.
  • Loading branch information
icculus committed Aug 6, 2017
1 parent 121ee38 commit a7ce178eecefb04daf4b402c07dcfc2c356e9d2f
Showing with 42 additions and 12 deletions.
  1. +26 −12 src/physfs.c
  2. +16 −0 src/physfs_internal.h
@@ -96,6 +96,30 @@ static int externalAllocator = 0;
PHYSFS_Allocator allocator;


#ifdef PHYSFS_NEED_ATOMIC_OP_FALLBACK
static inline int __PHYSFS_atomicAdd(int *ptrval, const int val)
{
int retval;
__PHYSFS_platformGrabMutex(stateLock);
retval = *ptrval;
*ptrval = retval + val;
__PHYSFS_platformReleaseMutex(stateLock);
return retval;
} /* __PHYSFS_atomicAdd */

int __PHYSFS_ATOMIC_INCR(int *ptrval)
{
return __PHYSFS_atomicAdd(ptrval, 1);
} /* __PHYSFS_ATOMIC_INCR */

int __PHYSFS_ATOMIC_DECR(int *ptrval)
{
return __PHYSFS_atomicAdd(ptrval, -1);
} /* __PHYSFS_ATOMIC_DECR */
#endif



/* PHYSFS_Io implementation for i/o to physical filesystem... */

/* !!! FIXME: maybe refcount the paths in a string pool? */
@@ -292,10 +316,7 @@ static PHYSFS_Io *memoryIo_duplicate(PHYSFS_Io *io)
BAIL(PHYSFS_ERR_OUT_OF_MEMORY, NULL);
} /* if */

/* !!! FIXME: want lockless atomic increment. */
__PHYSFS_platformGrabMutex(stateLock);
info->refcount++;
__PHYSFS_platformReleaseMutex(stateLock);
__PHYSFS_ATOMIC_INCR(&info->refcount);

memset(newinfo, '\0', sizeof (*info));
newinfo->buf = info->buf;
@@ -316,7 +337,6 @@ static void memoryIo_destroy(PHYSFS_Io *io)
{
MemoryIoInfo *info = (MemoryIoInfo *) io->opaque;
PHYSFS_Io *parent = info->parent;
int should_die = 0;

if (parent != NULL)
{
@@ -333,13 +353,7 @@ static void memoryIo_destroy(PHYSFS_Io *io)
/* we _are_ the parent. */
assert(info->refcount > 0); /* even in a race, we hold a reference. */

/* !!! FIXME: want lockless atomic decrement. */
__PHYSFS_platformGrabMutex(stateLock);
info->refcount--;
should_die = (info->refcount == 0);
__PHYSFS_platformReleaseMutex(stateLock);

if (should_die)
if (__PHYSFS_ATOMIC_DECR(&info->refcount) == 0)
{
void (*destruct)(void *) = info->destruct;
void *buf = (void *) info->buf;
@@ -104,6 +104,22 @@ const void *__PHYSFS_winrtCalcBaseDir(void);
const void *__PHYSFS_winrtCalcPrefDir(void);
#endif

/* atomic operations. */
#if defined(_MSC_VER) && (_MSC_VER >= 1500)
#include <intrin.h>
PHYSFS_COMPILE_TIME_ASSERT(LongEqualsInt, sizeof (int) == sizeof (long));
#define __PHYSFS_ATOMIC_INCR(ptrval) _InterlockedIncrement((long*)ptrval)
#define __PHYSFS_ATOMIC_INCR(ptrval) _InterlockedDecrement((long*)ptrval)
#elif defined(__clang__) || (defined(__GNUC__) && (((__GNUC__ * 10000) + (__GNUC_MINOR__ * 100)) >= 40100))
#define __PHYSFS_ATOMIC_INCR(ptrval) __sync_fetch_and_add(ptrval, 1)
#define __PHYSFS_ATOMIC_DECR(ptrval) __sync_fetch_and_add(ptrval, -1)
#else
#define PHYSFS_NEED_ATOMIC_OP_FALLBACK 1
int __PHYSFS_ATOMIC_INCR(int *ptrval);
int __PHYSFS_ATOMIC_DECR(int *ptrval);
#endif


/*
* Interface for small allocations. If you need a little scratch space for
* a throwaway buffer or string, use this. It will make small allocations

0 comments on commit a7ce178

Please sign in to comment.