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py: Improve GC locking/unlocking, and make it part of the API.

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This commit is contained in:
Damien George 2014-04-08 11:31:21 +00:00
parent ff5639fd42
commit 443e018a3f
2 changed files with 32 additions and 15 deletions
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37
py/gc.c
View File

@ -37,7 +37,7 @@ STATIC machine_uint_t *gc_pool_end;
STATIC int gc_stack_overflow;
STATIC machine_uint_t gc_stack[STACK_SIZE];
STATIC machine_uint_t *gc_sp;
STATIC bool gc_lock;
STATIC machine_uint_t gc_lock_depth;
// ATB = allocation table byte
// 0b00 = FREE -- free block
@ -130,7 +130,7 @@ void gc_init(void *start, void *end) {
}
// unlock the GC
gc_lock = false;
gc_lock_depth = 0;
DEBUG_printf("GC layout:\n");
DEBUG_printf(" alloc table at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", gc_alloc_table_start, gc_alloc_table_byte_len, gc_alloc_table_byte_len * BLOCKS_PER_ATB);
@ -140,6 +140,14 @@ void gc_init(void *start, void *end) {
DEBUG_printf(" pool at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", gc_pool_start, gc_pool_block_len * BYTES_PER_BLOCK, gc_pool_block_len);
}
void gc_lock(void) {
gc_lock_depth++;
}
void gc_unlock(void) {
gc_lock_depth--;
}
#define VERIFY_PTR(ptr) ( \
(ptr & (BYTES_PER_BLOCK - 1)) == 0 /* must be aligned on a block */ \
&& ptr >= (machine_uint_t)gc_pool_start /* must be above start of pool */ \
@ -238,7 +246,7 @@ STATIC void gc_sweep(void) {
}
void gc_collect_start(void) {
gc_lock = true;
gc_lock();
gc_stack_overflow = 0;
gc_sp = gc_stack;
}
@ -254,7 +262,7 @@ void gc_collect_root(void **ptrs, machine_uint_t len) {
void gc_collect_end(void) {
gc_deal_with_stack_overflow();
gc_sweep();
gc_lock = false;
gc_unlock();
}
void gc_info(gc_info_t *info) {
@ -306,8 +314,9 @@ void *gc_alloc(machine_uint_t n_bytes, bool has_finaliser) {
machine_uint_t n_blocks = ((n_bytes + BYTES_PER_BLOCK - 1) & (~(BYTES_PER_BLOCK - 1))) / BYTES_PER_BLOCK;
DEBUG_printf("gc_alloc(" UINT_FMT " bytes -> " UINT_FMT " blocks)\n", n_bytes, n_blocks);
if (gc_lock) {
// TODO
// check if GC is locked
if (gc_lock_depth > 0) {
return NULL;
}
// check for 0 allocation
@ -382,8 +391,9 @@ void *gc_alloc_with_finaliser(machine_uint_t n_bytes) {
// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
if (gc_lock) {
// TODO
if (gc_lock_depth > 0) {
// TODO how to deal with this error?
return;
}
machine_uint_t ptr = (machine_uint_t)ptr_in;
@ -420,7 +430,7 @@ machine_uint_t gc_nbytes(void *ptr_in) {
}
#if 0
// use this realloc for now, one below is broken
// old, simple realloc that didn't expand memory in place
void *gc_realloc(void *ptr, machine_uint_t n_bytes) {
machine_uint_t n_existing = gc_nbytes(ptr);
if (n_bytes <= n_existing) {
@ -436,10 +446,11 @@ void *gc_realloc(void *ptr, machine_uint_t n_bytes) {
return ptr2;
}
}
#else
#endif
void *gc_realloc(void *ptr_in, machine_uint_t n_bytes) {
if (gc_lock) {
// TODO
if (gc_lock_depth > 0) {
return NULL;
}
void *ptr_out = NULL;
@ -516,8 +527,6 @@ void *gc_realloc(void *ptr_in, machine_uint_t n_bytes) {
return ptr_out;
}
#endif
void gc_dump_info() {
gc_info_t info;
gc_info(&info);

10
py/gc.h
View File

@ -1,8 +1,16 @@
void gc_init(void *start, void *end);
// These lock/unlock functions can be nested.
// They can be used to prevent the GC from allocating/freeing.
void gc_lock(void);
void gc_unlock(void);
// A given port must implement gc_collect by using the other collect functions.
void gc_collect(void);
void gc_collect_start(void);
void gc_collect_root(void **ptrs, machine_uint_t len);
void gc_collect_end(void);
void gc_collect(void);
void *gc_alloc(machine_uint_t n_bytes, bool has_finaliser);
void gc_free(void *ptr);
machine_uint_t gc_nbytes(void *ptr);