Support efficient offstack allocations optionally.

lpcap.c

@@ -534,4 +534,34 @@ int getcaptures (lua_State *L, const char *s, const char *r, int ptop) {
   return n;
 }
 
-
+#ifdef NO_ONSTACK_LIGHTUSERDATA
+#include <stdlib.h>
+#include <pthread.h>
+
+#if !defined(INITBACK)
+#define INITBACK        MAXBACK
+#endif
+
+static pthread_mutex_t stack_on_heap_for_lp_match_init_lock = PTHREAD_MUTEX_INITIALIZER;
+static int stack_on_heap_for_lp_match_initialized;
+static pthread_key_t stack_on_heap_for_lp_match;
+struct tls_heap_compensator *lpcap_get_offstack_compenstor() {
+  struct tls_heap_compensator *comp;
+  comp = pthread_getspecific(stack_on_heap_for_lp_match);
+  if(comp == NULL) {
+    comp = calloc(1, sizeof(*comp) + INITCAPSIZE + INITBACK);
+    comp->alloc_capsize = (unsigned char *)comp + sizeof(*comp);
+    comp->alloc_back = (unsigned char *)comp->alloc_capsize + INITCAPSIZE;
+    pthread_setspecific(stack_on_heap_for_lp_match, comp);
+  }
+  return comp;
+}
+void lpcap_initiailize_offstack_compensator() {
+  pthread_mutex_lock(&stack_on_heap_for_lp_match_init_lock);
+  if(!stack_on_heap_for_lp_match_initialized) {
+    stack_on_heap_for_lp_match_initialized = 1;
+    pthread_key_create(&stack_on_heap_for_lp_match, free);
+  }
+  pthread_mutex_unlock(&stack_on_heap_for_lp_match_init_lock);
+}
+#endif

lpcap.h

@@ -33,11 +33,20 @@ typedef struct CapState {
   int valuecached;  /* value stored in cache slot */
 } CapState;
 
-
 int runtimecap (CapState *cs, Capture *close, const char *s, int *rem);
 int getcaptures (lua_State *L, const char *s, const char *r, int ptop);
 int finddyncap (Capture *cap, Capture *last);
 
+#ifdef NO_ONSTACK_LIGHTUSERDATA
+struct tls_heap_compensator {
+  void *alloc_capsize;
+  void *alloc_back;
+};
+
+struct tls_heap_compensator *lpcap_get_offstack_compenstor(void);
+void lpcap_initiailize_offstack_compensator(void);
+#endif
+
 #endif
 
 

lptree.c

@@ -1148,7 +1148,12 @@ static size_t initposition (lua_State *L, size_t len) {
 ** Main match function
 */
 static int lp_match (lua_State *L) {
-  Capture *capture = calloc(INITCAPSIZE, sizeof(Capture));
+#ifdef NO_ONSTACK_LIGHTUSERDATA
+  struct tls_heap_compensator *comp = lpcap_get_offstack_compenstor();
+  Capture *capture = comp->alloc_capsize;
+#else
+  Capture capture[INITCAPSIZE];
+#endif
   const char *r;
   size_t l;
   int rv;
@@ -1166,7 +1171,6 @@ static int lp_match (lua_State *L) {
     return 1;
   }
   rv = getcaptures(L, s, r, ptop);
-  free(capture);
   return rv;
 }
 
@@ -1287,6 +1291,9 @@ static struct luaL_Reg metareg[] = {
 
 int luaopen_lpeg (lua_State *L);
 int luaopen_lpeg (lua_State *L) {
+#ifdef NO_ONSTACK_LIGHTUSERDATA
+  lpcap_initiailize_offstack_compensator();
+#endif
   luaL_newmetatable(L, PATTERN_T);
   lua_pushnumber(L, MAXBACK);  /* initialize maximum backtracking */
   lua_setfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);

lpvm.c

@@ -147,7 +147,12 @@ static int removedyncap (lua_State *L, Capture *capture,
 */
 const char *match (lua_State *L, const char *o, const char *s, const char *e,
                    Instruction *op, Capture *capture, int ptop) {
-  Stack *stackbase = calloc(INITBACK, sizeof(Stack));
+#ifdef NO_ONSTACK_LIGHTUSERDATA
+  struct tls_heap_compensator *comp = lpcap_get_offstack_compenstor();
+  Stack *stackbase = comp->alloc_back;
+#else
+  Stack stackbase[INITBACK];
+#endif
   Stack *stacklimit = stackbase + INITBACK;
   Stack *stack = stackbase;  /* point to first empty slot in stack */
   int capsize = INITCAPSIZE;
@@ -169,12 +174,10 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         assert(stack == getstackbase(L, ptop) + 1);
         capture[captop].kind = Cclose;
         capture[captop].s = NULL;
-        free(stackbase);
         return s;
       }
       case IGiveup: {
         assert(stack == getstackbase(L, ptop));
-        free(stackbase);
         return NULL;
       }
       case IRet: {
@@ -348,7 +351,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         p++;
         continue;
       }
-      default: assert(0); free(stackbase); return NULL;
+      default: assert(0); return NULL;
     }
   }
 }