Multiple lua states per pattern

scripts/test.lua

@@ -0,0 +1,4 @@
+dispatch = function()
+
+	print 'argh'
+end

src/http/httpd_conf.c

@@ -16,6 +16,7 @@
 #include <util/log.h>
 #include <util/lua_util.h>
 #define PORT 8888
+#define DEFAULT_STATE_SIZE 3
 
 char *strdup(const char *s);
 
@@ -37,6 +38,8 @@ static struct mimetype json_mimetype = {"json", 4, "application/json", 16};
 
 static int load_scripts(httpd_conf_t *conf, lua_State *L) {
 	int i, entry, top, length, size;
+	int state_size;
+	lua_State *new_L;
 	const char *file, *mimetype, *pattern;
 	httpd_lua_state_t *states;
 	top = lua_gettop(L);
@@ -85,14 +88,14 @@ static int load_scripts(httpd_conf_t *conf, lua_State *L) {
 			size = lua_objlen(L, -1);
 			lua_pop(L, 1);
 			states[i].filename = strdup(file);
-			states[i].L = luaL_newstate();
-			luaL_openlibs(states[i].L);
-			luaL_loadfile(states[i].L, file);
+			new_L = luaL_newstate();
 
-			if (lua_eval(states[i].L) != 0) {
-				lua_close(states[i].L);
+			luaL_openlibs(new_L);
+			luaL_loadfile(new_L, file);
+
+			if (lua_eval(new_L) != 0) {
+				lua_close(new_L);
 				free((void*)states[i].filename);
-				states[i].L = NULL;
 				if (states[i].mimetype != mimetype) {
 					free((void*)states[i].mimetype);
 				}
@@ -101,6 +104,11 @@ static int load_scripts(httpd_conf_t *conf, lua_State *L) {
 				lua_pop(L, 1);
 				continue;
 			}
+			state_size = DEFAULT_STATE_SIZE;
+			states[i].idle_stack_size = state_size;
+			states[i].idle_state_top = 0;
+			states[i].idle_states = malloc(sizeof(lua_State*) * state_size);
+			states[i].idle_states[0] = new_L;
 
 			log_debug("%s is serving %s on %s", file, states[i].mimetype, states[i].pattern);
 			i += 1;

src/http/httpd_conf.h

@@ -18,8 +18,10 @@ typedef struct mimetype {
 
 typedef struct httpd_lua_state {
 	const char *pattern;
-	lua_State *L;
 	size_t pattern_size;
+	int idle_state_top;
+	int idle_stack_size;
+	lua_State **idle_states;
 	const char *filename;
 	const char *mimetype;
 } httpd_lua_state_t;

src/http/request_processor.c

@@ -71,14 +71,43 @@ static int send_header(FILE *fd, int status, const char *status_msg,
 
 }
 
+static lua_State *get_lua_state(httpd_lua_state_t *state) {
+	lua_State *L;
+	int stack_top;
+	stack_top = state->idle_state_top;
+	if (stack_top < 0) {
+		log_debug("Creating new state");
+		L = luaL_newstate();
+		luaL_openlibs(L);
+		luaL_loadfile(L, state->filename);
+		lua_eval(L);
+	} else {
+		L = state->idle_states[stack_top];
+		state->idle_state_top -= 1;
+	}
+	return L;
+}
+
+static void return_lua_state(httpd_lua_state_t *state, lua_State *L) {
+	int stack_top;
+	stack_top = state->idle_state_top;
+	if (stack_top-1 < state->idle_stack_size) {
+		stack_top += 1;
+		state->idle_states[stack_top] = L;
+		state->idle_state_top = stack_top;
+	} else {
+		lua_close(L);
+	}
+}
+
 static int http_lua_eval(http_parser *parser) {
 	struct http_conn_info *conn_info;
 	lua_State *L;
 	conn_info = (struct http_conn_info*)parser->data;
 
 	/* Send HTTP headers to client */
 	send_header(conn_info->client_fd, 200, "OK", conn_info->lua->mimetype);
-	L = conn_info->lua->L;
+	L = get_lua_state(conn_info->lua);
 	lua_settop(L, 0);
 	lua_getglobal(L, "dispatch");
 	lua_pushstring(L, conn_info->path);
@@ -91,6 +120,7 @@ static int http_lua_eval(http_parser *parser) {
 	default: lua_pushstring(L, "UNKNOWN");
 	}
 	lua_eval(L);
+	return_lua_state(conn_info->lua, L);
 	return 0;
 }
 
@@ -133,7 +163,7 @@ static int http_send_file(http_parser *parser) {
 	return 0;
 }
 
-static httpd_lua_state_t *get_lua_state(const httpd_conf_t *conf, const char* path) {
+static httpd_lua_state_t *get_script(const httpd_conf_t *conf, const char* path) {
 	httpd_lua_state_t *state;
 	state = conf->lua_states;
 	while (state != NULL && state->pattern != NULL) {
@@ -151,7 +181,7 @@ static int start_processing(http_parser *parser) {
 	httpd_lua_state_t *lua_state;
 	conn_info = (struct http_conn_info*)parser->data;
 
-	lua_state = get_lua_state(conn_info->conf, conn_info->path);
+	lua_state = get_script(conn_info->conf, conn_info->path);
 	log_debug("%s", conn_info->path);
 	if (lua_state != NULL) {
 		conn_info->type = 'L';