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https://github.com/mruby/mruby
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variable.c: reduce memory usage of instance variable table
This is a fundamentally simplified reimplementation of #5317 by @shuujii Instead of having array of `struct iv_elem`, we have sequences of keys and values packed in single chunk of malloc'ed memory. We don't have to worry about gaps from alignment, especially on 64 bit architecture, where `sizeof(struct iv_elem)` probably consumes 16 bytes, but `sizeof(mrb_sym)+sizeof(mrb_value)` is 12 bytes. In addition, this change could improve memory access locality. close #5317
This commit is contained in:
Yukihiro "Matz" Matsumoto
+48
-50
@@ -12,16 +12,11 @@
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#include <mruby/variable.h>
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#include <mruby/presym.h>
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struct iv_elem {
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mrb_sym key;
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mrb_value val;
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};
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/* Instance variable table structure */
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typedef struct iv_tbl {
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size_t size;
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size_t alloc;
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struct iv_elem *table;
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mrb_value *ptr;
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} iv_tbl;
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/* Creates the instance variable table. */
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@@ -33,7 +28,7 @@ iv_new(mrb_state *mrb)
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t = (iv_tbl*)mrb_malloc(mrb, sizeof(iv_tbl));
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t->size = 0;
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t->alloc = 0;
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t->table = NULL;
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t->ptr = NULL;
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return t;
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}
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@@ -45,67 +40,70 @@ iv_rehash(mrb_state *mrb, iv_tbl *t)
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{
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size_t old_alloc = t->alloc;
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size_t new_alloc = old_alloc+1;
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struct iv_elem *old_table = t->table;
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mrb_value *old_ptr = t->ptr;
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khash_power2(new_alloc);
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if (old_alloc == new_alloc) return;
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t->alloc = new_alloc;
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t->size = 0;
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t->table = (struct iv_elem*)mrb_calloc(mrb, sizeof(struct iv_elem), new_alloc);
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t->ptr = (mrb_value*)mrb_calloc(mrb, sizeof(mrb_value)+sizeof(mrb_sym), new_alloc);
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mrb_sym *keys = (mrb_sym*)&old_ptr[old_alloc];
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mrb_value *vals = old_ptr;
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for (size_t i = 0; i < old_alloc; i++) {
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struct iv_elem *slot = &old_table[i];
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/* key = 0 means empty; val = undef means deleted */
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if (slot->key != 0 && !mrb_undef_p(slot->val)) {
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iv_put(mrb, t, slot->key, slot->val);
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if (keys[i] != 0 && !mrb_undef_p(vals[i])) {
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iv_put(mrb, t, keys[i], vals[i]);
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}
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}
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mrb_free(mrb, old_table);
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mrb_free(mrb, old_ptr);
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}
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#define slot_empty_p(slot) ((slot)->key == 0 && !mrb_undef_p((slot)->val))
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#define slot_empty_p(k,v) ((k) == 0 && !mrb_undef_p(v))
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/* Set the value for the symbol in the instance variable table. */
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static void
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iv_put(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value val)
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{
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size_t hash, pos, start;
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struct iv_elem *dslot = NULL;
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int dpos = -1;
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if (t == NULL) return;
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if (t->alloc == 0) {
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iv_rehash(mrb, t);
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}
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mrb_sym *keys = (mrb_sym*)&t->ptr[t->alloc];
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mrb_value *vals = t->ptr;
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hash = kh_int_hash_func(mrb, sym);
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start = pos = hash & (t->alloc-1);
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for (;;) {
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struct iv_elem *slot = &t->table[pos];
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if (slot->key == sym) {
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slot->val = val;
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if (keys[pos] == sym) {
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vals[pos] = val;
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return;
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}
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else if (slot_empty_p(slot)) {
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else if (slot_empty_p(keys[pos], vals[pos])) {
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t->size++;
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slot->key = sym;
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slot->val = val;
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keys[pos] = sym;
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vals[pos] = val;
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return;
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}
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else if (!dslot && mrb_undef_p(slot->val)) { /* deleted */
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dslot = slot;
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else if (dpos < 0 && mrb_undef_p(vals[pos])) { /* deleted */
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dpos = pos;
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}
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pos = (pos+1) & (t->alloc-1);
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if (pos == start) { /* not found */
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if (dslot) {
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if (dpos >= 0) {
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t->size++;
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dslot->key = sym;
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dslot->val = val;
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keys[dpos] = sym;
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vals[dpos] = val;
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return;
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}
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/* no room */
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iv_rehash(mrb, t);
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keys = (mrb_sym*)&t->ptr[t->alloc];
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vals = t->ptr;
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start = pos = hash & (t->alloc-1);
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}
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}
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@@ -121,16 +119,16 @@ iv_get(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
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if (t->alloc == 0) return FALSE;
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if (t->size == 0) return FALSE;
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mrb_sym *keys = (mrb_sym*)&t->ptr[t->alloc];
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mrb_value *vals = t->ptr;
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hash = kh_int_hash_func(mrb, sym);
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start = pos = hash & (t->alloc-1);
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for (;;) {
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struct iv_elem *slot = &t->table[pos];
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if (slot->key == sym) {
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if (vp) *vp = slot->val;
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if (keys[pos] == sym) {
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if (vp) *vp = vals[pos];
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return TRUE;
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}
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else if (slot_empty_p(slot)) {
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else if (slot_empty_p(keys[pos], vals[pos])) {
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return FALSE;
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}
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pos = (pos+1) & (t->alloc-1);
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@@ -150,19 +148,19 @@ iv_del(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
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if (t->alloc == 0) return FALSE;
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if (t->size == 0) return FALSE;
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mrb_sym *keys = (mrb_sym*)&t->ptr[t->alloc];
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mrb_value *vals = t->ptr;
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hash = kh_int_hash_func(mrb, sym);
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start = pos = hash & (t->alloc-1);
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for (;;) {
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struct iv_elem *slot = &t->table[pos];
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if (slot->key == sym) {
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if (vp) *vp = slot->val;
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if (keys[pos] == sym) {
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if (vp) *vp = vals[pos];
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t->size--;
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slot->key = 0;
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slot->val = mrb_undef_value();
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keys[pos] = 0;
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vals[pos] = mrb_undef_value();
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return TRUE;
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}
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else if (slot_empty_p(slot)) {
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else if (slot_empty_p(keys[pos], vals[pos])) {
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return FALSE;
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}
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pos = (pos+1) & (t->alloc-1);
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@@ -182,11 +180,11 @@ iv_foreach(mrb_state *mrb, iv_tbl *t, mrb_iv_foreach_func *func, void *p)
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if (t->alloc == 0) return;
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if (t->size == 0) return;
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mrb_sym *keys = (mrb_sym*)&t->ptr[t->alloc];
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mrb_value *vals = t->ptr;
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for (i=0; i<t->alloc; i++) {
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struct iv_elem *slot = &t->table[i];
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if (slot->key && !mrb_undef_p(slot->val)) {
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if ((*func)(mrb, slot->key, slot->val, p) != 0) {
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if (keys[i] && !mrb_undef_p(vals[i])) {
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if ((*func)(mrb, keys[i], vals[i], p) != 0) {
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return;
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}
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}
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@@ -213,12 +211,12 @@ iv_copy(mrb_state *mrb, iv_tbl *t)
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if (t->alloc == 0) return NULL;
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if (t->size == 0) return NULL;
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mrb_sym *keys = (mrb_sym*)&t->ptr[t->alloc];
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mrb_value *vals = t->ptr;
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t2 = iv_new(mrb);
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for (i=0; i<t->alloc; i++) {
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struct iv_elem *slot = &t->table[i];
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if (slot->key && !mrb_undef_p(slot->val)) {
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iv_put(mrb, t2, slot->key, slot->val);
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if (keys[i] && !mrb_undef_p(vals[i])) {
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iv_put(mrb, t2, keys[i], vals[i]);
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}
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}
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return t2;
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@@ -228,7 +226,7 @@ iv_copy(mrb_state *mrb, iv_tbl *t)
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static void
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iv_free(mrb_state *mrb, iv_tbl *t)
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{
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mrb_free(mrb, t->table);
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mrb_free(mrb, t->ptr);
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mrb_free(mrb, t);
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}
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@@ -1125,7 +1123,7 @@ mrb_obj_iv_tbl_memsize(mrb_value obj)
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{
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iv_tbl *t = mrb_obj_ptr(obj)->iv;
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if (t == NULL) return 0;
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return sizeof(iv_tbl) + t->alloc*sizeof(struct iv_elem);
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return sizeof(iv_tbl) + t->alloc*(sizeof(mrb_value)+sizeof(mrb_sym));
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}
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#define identchar(c) (ISALNUM(c) || (c) == '_' || !ISASCII(c))
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