diff options
Diffstat (limited to 'libguile/gc.h')
-rw-r--r-- | libguile/gc.h | 57 |
1 files changed, 36 insertions, 21 deletions
diff --git a/libguile/gc.h b/libguile/gc.h index 4cb78a714..baf77fa66 100644 --- a/libguile/gc.h +++ b/libguile/gc.h @@ -29,6 +29,34 @@ +/* Cell allocation and garbage collection work rouhgly in the + following manner: + + Each thread has a 'freelist', which is a list of available cells. + (It actually has two freelists, one for single cells and one for + double cells. Everything works analogous for double cells.) + + When a thread wants to allocate a cell and the freelist is empty, + it refers to a global list of unswept 'cards'. A card is a small + block of cells that are contigous in memory, together with the + corresponding mark bits. A unswept card is one where the mark bits + are set for cells that have been in use during the last global mark + phase, but the unmarked cells of the card have not been scanned and + freed yet. + + The thread takes one of the unswept cards and sweeps it, thereby + building a new freelist that it then uses. Sweeping a card will + call the smob free functions of unmarked cells, for example, and + thus, these free functions can run at any time, in any thread. + + When there are no more unswept cards available, the thread performs + a global garbage collection. For this, all other threads are + stopped. A global mark is performed and all cards are put into the + global list of unswept cards. Whennecessary, new cards are + allocated and initialized at this time. The other threads are then + started again. +*/ + typedef struct scm_t_cell { SCM word_0; @@ -66,7 +94,7 @@ typedef struct scm_t_cell #define SCM_GC_CARD_N_HEADER_CELLS 1 #define SCM_GC_CARD_N_CELLS 256 -#define SCM_GC_SIZEOF_CARD SCM_GC_CARD_N_CELLS * sizeof (scm_t_cell) +#define SCM_GC_SIZEOF_CARD SCM_GC_CARD_N_CELLS * sizeof (scm_t_cell) #define SCM_GC_CARD_BVEC(card) ((scm_t_c_bvec_long *) ((card)->word_0)) #define SCM_GC_SET_CARD_BVEC(card, bvec) \ @@ -187,6 +215,10 @@ typedef unsigned long scm_t_c_bvec_long; #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT ((x), 2, (v)) #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT ((x), 3, (v)) +#define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n)))) +#define SCM_CARLOC(x) (SCM_CELL_OBJECT_LOC ((x), 0)) +#define SCM_CDRLOC(x) (SCM_CELL_OBJECT_LOC ((x), 1)) + #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x) #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 ((x), (t)) @@ -195,27 +227,11 @@ typedef unsigned long scm_t_c_bvec_long; * the freelist. Due to this structure, freelist cells are not cons cells * and thus may not be accessed using SCM_CAR and SCM_CDR. */ -/* - SCM_FREECELL_P removed ; the semantics are ambiguous with lazy - sweeping. Could mean "this cell is no longer in use (will be swept)" - or "this cell has just been swept, and is not yet in use". - */ - -#define SCM_FREECELL_P this_macro_has_been_removed_see_gc_header_file - #define SCM_FREE_CELL_CDR(x) \ (SCM_GC_CELL_OBJECT ((x), 1)) #define SCM_SET_FREE_CELL_CDR(x, v) \ (SCM_GC_SET_CELL_OBJECT ((x), 1, (v))) - -#define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n)))) -#define SCM_CARLOC(x) (SCM_CELL_OBJECT_LOC ((x), 0)) -#define SCM_CDRLOC(x) (SCM_CELL_OBJECT_LOC ((x), 1)) - - - - #if (SCM_DEBUG_CELL_ACCESSES == 1) /* Set this to != 0 if every cell that is accessed shall be checked: */ @@ -227,10 +243,9 @@ void scm_i_expensive_validation_check (SCM cell); SCM_API scm_i_pthread_mutex_t scm_i_gc_admin_mutex; -SCM_API int scm_block_gc; -SCM_API int scm_gc_heap_lock; -SCM_API unsigned int scm_gc_running_p; +#define scm_gc_running_p (SCM_I_CURRENT_THREAD->gc_running_p) SCM_API scm_i_pthread_mutex_t scm_i_sweep_mutex; + #if (SCM_ENABLE_DEPRECATED == 1) @@ -305,7 +320,7 @@ SCM_API SCM scm_gc_live_object_stats (void); SCM_API SCM scm_gc (void); SCM_API void scm_gc_for_alloc (struct scm_t_cell_type_statistics *freelist); SCM_API SCM scm_gc_for_newcell (struct scm_t_cell_type_statistics *master, SCM *freelist); -SCM_API void scm_igc (const char *what); +SCM_API void scm_i_gc (const char *what); SCM_API void scm_gc_mark (SCM p); SCM_API void scm_gc_mark_dependencies (SCM p); SCM_API void scm_mark_locations (SCM_STACKITEM x[], unsigned long n); |