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Code Issues 1 Releases Wiki Activity

Garbage collection no longer blows stack.

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This commit is contained in:
Calvin Rose 2018-09-22 14:59:50 -04:00
parent 486ce6bc81
commit d9752a9028
3 changed files with 58 additions and 55 deletions
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90
src/core/gc.c
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@ -31,10 +31,11 @@ JANET_THREAD_LOCAL uint32_t janet_vm_gc_interval;
JANET_THREAD_LOCAL uint32_t janet_vm_next_collection; JANET_THREAD_LOCAL uint32_t janet_vm_next_collection;
JANET_THREAD_LOCAL int janet_vm_gc_suspend = 0; JANET_THREAD_LOCAL int janet_vm_gc_suspend = 0;
/* Roots */ /* GC mark state */
JANET_THREAD_LOCAL Janet *janet_vm_roots; JANET_THREAD_LOCAL Janet *janet_vm_gc_marklist = NULL;
JANET_THREAD_LOCAL uint32_t janet_vm_root_count; JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_count = 0;
JANET_THREAD_LOCAL uint32_t janet_vm_root_capacity; JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_capacity = 0;
JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_rootcount = 0;
/* Helpers for marking the various gc types */ /* Helpers for marking the various gc types */
static void janet_mark_funcenv(JanetFuncEnv *env); static void janet_mark_funcenv(JanetFuncEnv *env);
@ -49,21 +50,17 @@ static void janet_mark_string(const uint8_t *str);
static void janet_mark_fiber(JanetFiber *fiber); static void janet_mark_fiber(JanetFiber *fiber);
static void janet_mark_abstract(void *adata); static void janet_mark_abstract(void *adata);
/* Mark a value */ /* Mark a value (Pushes it to the black list).*/
void janet_mark(Janet x) { void janet_mark(Janet x) {
switch (janet_type(x)) { if (janet_vm_gc_marklist_count >= janet_vm_gc_marklist_capacity) {
default: break; janet_vm_gc_marklist_capacity = (3 * janet_vm_gc_marklist_count) / 2 + 1;
case JANET_STRING: janet_vm_gc_marklist = realloc(janet_vm_gc_marklist,
case JANET_SYMBOL: janet_mark_string(janet_unwrap_string(x)); break; janet_vm_gc_marklist_capacity * sizeof(Janet));
case JANET_FUNCTION: janet_mark_function(janet_unwrap_function(x)); break; if (NULL == janet_vm_gc_marklist) {
case JANET_ARRAY: janet_mark_array(janet_unwrap_array(x)); break; JANET_OUT_OF_MEMORY;
case JANET_TABLE: janet_mark_table(janet_unwrap_table(x)); break; }
case JANET_STRUCT: janet_mark_struct(janet_unwrap_struct(x)); break;
case JANET_TUPLE: janet_mark_tuple(janet_unwrap_tuple(x)); break;
case JANET_BUFFER: janet_mark_buffer(janet_unwrap_buffer(x)); break;
case JANET_FIBER: janet_mark_fiber(janet_unwrap_fiber(x)); break;
case JANET_ABSTRACT: janet_mark_abstract(janet_unwrap_abstract(x)); break;
} }
janet_vm_gc_marklist[janet_vm_gc_marklist_count++] = x;
} }
static void janet_mark_string(const uint8_t *str) { static void janet_mark_string(const uint8_t *str) {
@ -86,10 +83,8 @@ static void janet_mark_abstract(void *adata) {
/* Mark a bunch of items in memory */ /* Mark a bunch of items in memory */
static void janet_mark_many(const Janet *values, int32_t n) { static void janet_mark_many(const Janet *values, int32_t n) {
const Janet *end = values + n; const Janet *end = values + n;
while (values < end) { while (values < end)
janet_mark(*values); janet_mark(*values++);
values += 1;
}
} }
/* Mark a bunch of key values items in memory */ /* Mark a bunch of key values items in memory */
@ -315,10 +310,28 @@ void *janet_gcalloc(enum JanetMemoryType type, size_t size) {
/* Run garbage collection */ /* Run garbage collection */
void janet_collect(void) { void janet_collect(void) {
uint32_t i; size_t i;
if (janet_vm_gc_suspend) return; if (janet_vm_gc_suspend) return;
for (i = 0; i < janet_vm_root_count; i++) /* Mark the roots */
janet_mark(janet_vm_roots[i]); for (i = 0; i < janet_vm_gc_marklist_rootcount; i++)
janet_mark(janet_vm_gc_marklist[i]);
/* While list not empty */
while (janet_vm_gc_marklist_count > janet_vm_gc_marklist_rootcount) {
Janet x = janet_vm_gc_marklist[--janet_vm_gc_marklist_count];
switch (janet_type(x)) {
default: break;
case JANET_STRING:
case JANET_SYMBOL: janet_mark_string(janet_unwrap_string(x)); break;
case JANET_FUNCTION: janet_mark_function(janet_unwrap_function(x)); break;
case JANET_ARRAY: janet_mark_array(janet_unwrap_array(x)); break;
case JANET_TABLE: janet_mark_table(janet_unwrap_table(x)); break;
case JANET_STRUCT: janet_mark_struct(janet_unwrap_struct(x)); break;
case JANET_TUPLE: janet_mark_tuple(janet_unwrap_tuple(x)); break;
case JANET_BUFFER: janet_mark_buffer(janet_unwrap_buffer(x)); break;
case JANET_FIBER: janet_mark_fiber(janet_unwrap_fiber(x)); break;
case JANET_ABSTRACT: janet_mark_abstract(janet_unwrap_abstract(x)); break;
}
}
janet_sweep(); janet_sweep();
janet_vm_next_collection = 0; janet_vm_next_collection = 0;
} }
@ -327,17 +340,8 @@ void janet_collect(void) {
* and all of its children. If gcroot is called on a value n times, unroot * and all of its children. If gcroot is called on a value n times, unroot
* must also be called n times to remove it as a gc root. */ * must also be called n times to remove it as a gc root. */
void janet_gcroot(Janet root) { void janet_gcroot(Janet root) {
uint32_t newcount = janet_vm_root_count + 1; janet_mark(root);
if (newcount > janet_vm_root_capacity) { janet_vm_gc_marklist_rootcount++;
uint32_t newcap = 2 * newcount;
janet_vm_roots = realloc(janet_vm_roots, sizeof(Janet) * newcap);
if (NULL == janet_vm_roots) {
JANET_OUT_OF_MEMORY;
}
janet_vm_root_capacity = newcap;
}
janet_vm_roots[janet_vm_root_count] = root;
janet_vm_root_count = newcount;
} }
/* Identity equality for GC purposes */ /* Identity equality for GC purposes */
@ -361,12 +365,12 @@ static int janet_gc_idequals(Janet lhs, Janet rhs) {
/* Remove a root value from the GC. This allows the gc to potentially reclaim /* Remove a root value from the GC. This allows the gc to potentially reclaim
* a value and all its children. */ * a value and all its children. */
int janet_gcunroot(Janet root) { int janet_gcunroot(Janet root) {
Janet *vtop = janet_vm_roots + janet_vm_root_count; Janet *vtop = janet_vm_gc_marklist + janet_vm_gc_marklist_rootcount;
Janet *v = janet_vm_roots; Janet *v = janet_vm_gc_marklist;
/* Search from top to bottom as access is most likely LIFO */ /* Search from top to bottom as access is most likely LIFO */
for (v = janet_vm_roots; v < vtop; v++) { for (v = janet_vm_gc_marklist; v < vtop; v++) {
if (janet_gc_idequals(root, *v)) { if (janet_gc_idequals(root, *v)) {
*v = janet_vm_roots[--janet_vm_root_count]; *v = janet_vm_gc_marklist[--janet_vm_gc_marklist_rootcount];
return 1; return 1;
} }
} }
@ -375,13 +379,13 @@ int janet_gcunroot(Janet root) {
/* Remove a root value from the GC. This sets the effective reference count to 0. */ /* Remove a root value from the GC. This sets the effective reference count to 0. */
int janet_gcunrootall(Janet root) { int janet_gcunrootall(Janet root) {
Janet *vtop = janet_vm_roots + janet_vm_root_count; Janet *vtop = janet_vm_gc_marklist + janet_vm_gc_marklist_rootcount;
Janet *v = janet_vm_roots; Janet *v = janet_vm_gc_marklist;
int ret = 0; int ret = 0;
/* Search from top to bottom as access is most likely LIFO */ /* Search from top to bottom as access is most likely LIFO */
for (v = janet_vm_roots; v < vtop; v++) { for (v = janet_vm_gc_marklist; v < vtop; v++) {
if (janet_gc_idequals(root, *v)) { if (janet_gc_idequals(root, *v)) {
*v = janet_vm_roots[--janet_vm_root_count]; *v = janet_vm_gc_marklist[--janet_vm_gc_marklist_rootcount];
vtop--; vtop--;
ret = 1; ret = 1;
} }

8
src/core/state.h
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@ -55,9 +55,9 @@ extern JANET_THREAD_LOCAL uint32_t janet_vm_gc_interval;
extern JANET_THREAD_LOCAL uint32_t janet_vm_next_collection; extern JANET_THREAD_LOCAL uint32_t janet_vm_next_collection;
extern JANET_THREAD_LOCAL int janet_vm_gc_suspend; extern JANET_THREAD_LOCAL int janet_vm_gc_suspend;
/* GC roots */ extern JANET_THREAD_LOCAL Janet *janet_vm_gc_marklist;
extern JANET_THREAD_LOCAL Janet *janet_vm_roots; extern JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_count;
extern JANET_THREAD_LOCAL uint32_t janet_vm_root_count; extern JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_capacity;
extern JANET_THREAD_LOCAL uint32_t janet_vm_root_capacity; extern JANET_THREAD_LOCAL size_t janet_vm_gc_marklist_rootcount;
#endif /* JANET_STATE_H_defined */ #endif /* JANET_STATE_H_defined */

15
src/core/vm.c
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@ -1335,10 +1335,11 @@ int janet_init(void) {
* there are no memory bugs during development */ * there are no memory bugs during development */
janet_vm_gc_interval = 0x1000000; janet_vm_gc_interval = 0x1000000;
janet_symcache_init(); janet_symcache_init();
/* Initialize gc roots */ /* Initialize gc list */
janet_vm_roots = NULL; janet_vm_gc_marklist = NULL;
janet_vm_root_count = 0; janet_vm_gc_marklist_count = 0;
janet_vm_root_capacity = 0; janet_vm_gc_marklist_capacity = 0;
janet_vm_gc_marklist_rootcount = 0;
/* Initialize registry */ /* Initialize registry */
janet_vm_registry = janet_table(0); janet_vm_registry = janet_table(0);
janet_gcroot(janet_wrap_table(janet_vm_registry)); janet_gcroot(janet_wrap_table(janet_vm_registry));
@ -1349,9 +1350,7 @@ int janet_init(void) {
void janet_deinit(void) { void janet_deinit(void) {
janet_clear_memory(); janet_clear_memory();
janet_symcache_deinit(); janet_symcache_deinit();
free(janet_vm_roots); free(janet_vm_gc_marklist);
janet_vm_roots = NULL; janet_vm_gc_marklist = NULL;
janet_vm_root_count = 0;
janet_vm_root_capacity = 0;
janet_vm_registry = NULL; janet_vm_registry = NULL;
} }