O(1) mrb_sym2name_len(); close #2591

instead of adding sym->name hash table, linear symbol table is added, and reduced name->sym hash table size.

include/mruby.h

@@ -165,7 +165,9 @@ typedef struct mrb_state {
   struct alloca_header *mems;
 
   mrb_sym symidx;
-  struct kh_n2s *name2sym;      /* symbol table */
+  struct kh_n2s *name2sym;      /* symbol hash */
+  struct symbol_name *symtbl;   /* symbol table */
+  size_t symcapa;
 
 #ifdef ENABLE_DEBUG
   void (*code_fetch_hook)(struct mrb_state* mrb, struct mrb_irep *irep, mrb_code *pc, mrb_value *regs);

mrbgems/mruby-symbol-ext/src/symbol.c

@@ -7,8 +7,6 @@ typedef struct symbol_name {
   const char *name;
 } symbol_name;
 
-KHASH_DECLARE(n2s, symbol_name, mrb_sym, TRUE)
-
 /*
  *  call-seq:
  *     Symbol.all_symbols    => array
@@ -27,16 +25,11 @@ KHASH_DECLARE(n2s, symbol_name, mrb_sym, TRUE)
 static mrb_value
 mrb_sym_all_symbols(mrb_state *mrb, mrb_value self)
 {
-  khiter_t k;
-  mrb_sym sym;
-  khash_t(n2s) *h = mrb->name2sym;
-  mrb_value ary = mrb_ary_new_capa(mrb, kh_size(h));
+  mrb_sym i, lim;
+  mrb_value ary = mrb_ary_new_capa(mrb, mrb->symidx);
 
-  for (k = kh_begin(h); k != kh_end(h); k++) {
-    if (kh_exist(h, k)) {
-      sym = kh_value(h, k);
-      mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
-    }
+  for (i=1, lim=mrb->symidx+1; i<lim; i++) {
+    mrb_ary_push(mrb, ary, mrb_symbol_value(i));
   }
 
   return ary;

src/symbol.c

@@ -20,21 +20,21 @@ typedef struct symbol_name {
 } symbol_name;
 
 static inline khint_t
-sym_hash_func(mrb_state *mrb, const symbol_name s)
+sym_hash_func(mrb_state *mrb, mrb_sym s)
 {
   khint_t h = 0;
-  size_t i;
-  const char *p = s.name;
+  size_t i, len = mrb->symtbl[s].len;;
+  const char *p = mrb->symtbl[s].name;
 
-  for (i=0; i<s.len; i++) {
+  for (i=0; i<len; i++) {
     h = (h << 5) - h + *p++;
   }
   return h;
 }
-#define sym_hash_equal(mrb,a, b) (a.len == b.len && memcmp(a.name, b.name, a.len) == 0)
+#define sym_hash_equal(mrb,a, b) (mrb->symtbl[a].len == mrb->symtbl[b].len && memcmp(mrb->symtbl[a].name, mrb->symtbl[b].name, mrb->symtbl[a].len) == 0)
 
-KHASH_DECLARE(n2s, symbol_name, mrb_sym, TRUE)
-KHASH_DEFINE (n2s, symbol_name, mrb_sym, TRUE, sym_hash_func, sym_hash_equal)
+KHASH_DECLARE(n2s, mrb_sym, mrb_sym, FALSE)
+KHASH_DEFINE (n2s, mrb_sym, mrb_sym, FALSE, sym_hash_func, sym_hash_equal)
 /* ------------------------------------------------------ */
 
 static void
@@ -49,31 +49,42 @@ static mrb_sym
 sym_intern(mrb_state *mrb, const char *name, size_t len, mrb_bool lit)
 {
   khash_t(n2s) *h = mrb->name2sym;
-  symbol_name sname;
+  symbol_name *sname = mrb->symtbl; /* symtbl[0] for working memory */
   khiter_t k;
   mrb_sym sym;
   char *p;
 
   sym_validate_len(mrb, len);
-  sname.lit = lit;
-  sname.len = (uint16_t)len;
-  sname.name = name;
-  k = kh_get(n2s, mrb, h, sname);
-  if (k != kh_end(h))
-    return kh_value(h, k);
+  if (sname) {
+    sname->lit = lit;
+    sname->len = (uint16_t)len;
+    sname->name = name;
+    k = kh_get(n2s, mrb, h, 0);
+    if (k != kh_end(h))
+      return kh_key(h, k);
+  }
 
+  /* registering a new symbol */
   sym = ++mrb->symidx;
+  if (mrb->symcapa < sym) {
+    if (mrb->symcapa == 0) mrb->symcapa = 100;
+    else mrb->symcapa *= 1.2;
+    mrb->symtbl = (symbol_name*)mrb_realloc(mrb, mrb->symtbl, sizeof(symbol_name)*(mrb->symcapa+1));
+  }
+  sname = &mrb->symtbl[sym];
+  sname->len = (uint16_t)len;
   if (lit) {
-    sname.name = name;
+    sname->name = name;
+    sname->lit = TRUE;
   }
   else {
     p = (char *)mrb_malloc(mrb, len+1);
     memcpy(p, name, len);
     p[len] = 0;
-    sname.name = (const char*)p;
+    sname->name = (const char*)p;
+    sname->lit = FALSE;
   }
-  k = kh_put(n2s, mrb, h, sname);
-  kh_value(h, k) = sym;
+  kh_put(n2s, mrb, h, sym);
 
   return sym;
 }
@@ -106,16 +117,16 @@ MRB_API mrb_value
 mrb_check_intern(mrb_state *mrb, const char *name, size_t len)
 {
   khash_t(n2s) *h = mrb->name2sym;
-  symbol_name sname = { 0 };
+  symbol_name *sname = mrb->symtbl;
   khiter_t k;
 
   sym_validate_len(mrb, len);
-  sname.len = (uint16_t)len;
-  sname.name = name;
+  sname->len = (uint16_t)len;
+  sname->name = name;
 
-  k = kh_get(n2s, mrb, h, sname);
+  k = kh_get(n2s, mrb, h, 0);
   if (k != kh_end(h)) {
-    return mrb_symbol_value(kh_value(h, k));
+    return mrb_symbol_value(kh_key(h, k));
   }
   return mrb_nil_value();
 }
@@ -136,37 +147,25 @@ mrb_check_intern_str(mrb_state *mrb, mrb_value str)
 MRB_API const char*
 mrb_sym2name_len(mrb_state *mrb, mrb_sym sym, mrb_int *lenp)
 {
-  khash_t(n2s) *h = mrb->name2sym;
-  khiter_t k;
-  symbol_name sname;
-
-  for (k = kh_begin(h); k != kh_end(h); k++) {
-    if (kh_exist(h, k)) {
-      if (kh_value(h, k) == sym) {
-        sname = kh_key(h, k);
-        if (lenp) *lenp = sname.len;
-        return sname.name;
-      }
-    }
+  if (sym == 0 || mrb->symidx < sym) {
+    return NULL;
   }
-  if (lenp) *lenp = 0;
-  return NULL;  /* missing */
+
+  if (lenp) *lenp = mrb->symtbl[sym].len;
+  return mrb->symtbl[sym].name;
 }
 
 void
 mrb_free_symtbl(mrb_state *mrb)
 {
-  khash_t(n2s) *h = mrb->name2sym;
-  khiter_t k;
+  mrb_sym i, lim;
 
-  for (k = kh_begin(h); k != kh_end(h); k++)
-    if (kh_exist(h, k)) {
-      symbol_name s = kh_key(h, k);
-
-      if (!s.lit) {
-        mrb_free(mrb, (char*)s.name);
-      }
+  for (i=1, lim=mrb->symidx+1; i<lim; i++) {
+    if (!mrb->symtbl[i].lit) {
+      mrb_free(mrb, (char*)mrb->symtbl[i].name);
     }
+  }
+  mrb_free(mrb, mrb->symtbl);
   kh_destroy(n2s, mrb, mrb->name2sym);
 }