add semaphore for mainthread api

Author: cloudwu

src/ltask.c

@@ -26,6 +26,7 @@
 #include "logqueue.h"
 #include "systime.h"
 #include "threadsig.h"
+#include "semaphore.h"
 
 LUAMOD_API int luaopen_ltask(lua_State *L);
 LUAMOD_API int luaopen_ltask_bootstrap(lua_State *L);
@@ -52,23 +53,23 @@ LUAMOD_API int luaopen_ltask_root(lua_State *L);
 
 struct mainthread_session {
 	atomic_int srv;
-	struct cond ev;
+	struct sem ev;
 	int status;
 };
 
 static void
 mainthread_init(struct mainthread_session *mt) {
 	atomic_int_init(&mt->srv, 0);
 	mt->status = MAINTHREAD_STATUS_NONE;
-	cond_create(&mt->ev);
+	sem_init(&mt->ev);
 }
 
 static void
 mainthread_deinit(struct mainthread_session *mt) {
 	assert(mt->status == MAINTHREAD_STATUS_NONE || mt->status == MAINTHREAD_STATUS_YIELD);
 	atomic_int_store(&mt->srv, 0);
 	mt->status = MAINTHREAD_STATUS_INVALID;
-	cond_release(&mt->ev);
+	sem_deinit(&mt->ev);
 }
 
 static inline int
@@ -78,8 +79,7 @@ mainthread_current(struct mainthread_session *mt, service_id id) {
 
 static inline void
 mainthread_trigger(struct mainthread_session *mt) {
-	cond_trigger_begin(&mt->ev);
-	cond_trigger_end(&mt->ev, 1);
+	sem_release(&mt->ev);
 }
 
 struct ltask {
@@ -1153,11 +1153,13 @@ lmainthread_wait(lua_State *L) {
 	if (mt->status != MAINTHREAD_STATUS_NONE && mt->status != MAINTHREAD_STATUS_READY)
 		return luaL_error(L, "mainthread in use");
 	struct service_pool * P = task->services;
+	int inf = !lua_toboolean(L, 1);
 	int finish = 0;
 	do {
-		cond_wait_begin(&mt->ev);
-		cond_wait(&mt->ev);
-		cond_wait_end(&mt->ev);
+		if (sem_acquire(&mt->ev, inf)) {
+			lua_pushboolean(L, 1);	// fail
+			return 1;
+		}
 		if (mt->status != MAINTHREAD_STATUS_READY)
 			luaL_error(L, "mainthread not ready");
 
@@ -1196,7 +1198,8 @@ lmainthread_wait(lua_State *L) {
 		schedule_back(task, id);
 		mt->status = MAINTHREAD_STATUS_NONE;
 	} while (!finish);
-	atomic_int_store(&mt->srv, 0);	return 0;
+	atomic_int_store(&mt->srv, 0);
+	return 0;
 }
 
 LUAMOD_API int

src/semaphore.h

@@ -0,0 +1,36 @@
+#ifndef ltask_semaphore_h
+#define ltask_semaphore_h
+
+#include "cond.h"
+
+struct sem {
+	struct cond c;
+};
+
+static inline void
+sem_init(struct sem *s) {
+	cond_create(&s->c);
+}
+
+static inline void
+sem_deinit(struct sem *s) {
+	cond_release(&s->c);
+}
+
+static inline int
+sem_acquire(struct sem *s, int inf) {
+	// ignore inf, always wait inf
+	cond_wait_begin(&s->c);
+	cond_wait(&s->c);
+	cond_wait_end(&s->c);
+	// fail would return -1 (inf == 0)
+	return 0;
+}
+
+static inline void
+sem_release(struct sem *s) {
+	cond_trigger_begin(&s->c);
+	cond_trigger_end(&s->c, 1);
+}
+
+#endif