changed the scheduler to reset the return value of the wait context of a semaphore group forcibly to a singaled semaphore.

added the waitWithTimeout method to a semaphore group

moo/kernel/Process.moo

@@ -79,8 +79,12 @@ class Semaphore(Object)
 TODO: timed wait...
 	method waitWithTimeout: seconds
 	{
-		<primitive: #_semaphore_wait>
-		self primitiveFailed
+		| s |
+		s := Semaphore new.
+		Processor signal: s after: seconds.
+		self waitWithTimedSemaphore: s.
+
+		if (self.
 	}
 
 	method waitWithTimeout: seconds and: nanoSeconds
@@ -89,6 +93,7 @@ TODO: timed wait...
 		self primitiveFailed
 	}
 *)
+
 	method critical: aBlock
 	{
 		self wait.
@@ -194,7 +199,6 @@ class SemaphoreGroup(Object)
 	    size := 0,
 	    pos := 0,
 	    semarr := nil.
-	var(#get,#set) signaledSemaphore := nil.
 
 (* TODO: good idea to a shortcut way to prohibit a certain method in the heirarchy chain?
 
@@ -250,6 +254,36 @@ method(#class,#abstract) xxx. => method(#class) xxx { self subclassResponsibilit
 	}
 
 	method(#primitive) wait.
+
+	method waitWithTimeout: seconds
+	{
+		| s r |
+
+		## create an internal semaphore for timeout notification.
+		s := Semaphore new. 
+
+		## grant the partial membership to the internal semaphore.
+		## it's partial because it's not added to self.semarr.
+		s _group: self. 
+
+		## arrange the processor to notify upon timeout.
+		Processor signal: s after: seconds. 
+
+		## wait on the semaphore group.
+		r := self wait.
+
+		## if the internal semaphore has been signaled, 
+		## arrange to return nil to indicate timeout.
+		if (r == s) { r := nil }.
+
+		## nullify the membership
+		s _group: nil. 
+
+		## cancel the notification arrangement in case it didn't time out.
+		Processor unsignal: s.
+
+		^r.
+	} 
 }
 
 class SemaphoreHeap(Object)

moo/lib/exec.c

@@ -214,7 +214,6 @@ static MOO_INLINE int prepare_to_alloc_pid (moo_t* moo)
 	moo->proc_map = tmp;
 	moo->proc_map_capa = new_capa;
 
-
 	return 0;
 }
 
@@ -745,8 +744,15 @@ static moo_oop_process_t signal_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
 			unchain_from_semaphore (moo, proc);
 			resume_process (moo, proc);
 
-			/* store the last signaled semaphore into the semaphore group */
-			semgrp->sigsem = sem; 
+			/* the waiting process has been suspended after a waiting
+			 * primitive function in Semaphore or SemaphoreGroup.
+			 * the top of the stack of the process must hold the temporary 
+			 * return value set by await_semaphore() or await_semaphore_group().
+			 * change the return value forcibly to the actual signaled 
+			 * semaphore */
+			MOO_ASSERT (moo, MOO_OOP_TO_SMOOI(proc->sp) < (moo_ooi_t)(MOO_OBJ_GET_SIZE(proc) - MOO_PROCESS_NAMED_INSTVARS));
+			proc->slot[MOO_OOP_TO_SMOOI(proc->sp)] = (moo_oop_t)sem;
+
 			return proc;
 		}
 	}
@@ -790,7 +796,7 @@ static moo_oop_process_t signal_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
 	}
 }
 
-static MOO_INLINE int await_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
+static MOO_INLINE void await_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
 {
 /* TODO: support timeout */
 	moo_oop_process_t proc;
@@ -831,10 +837,12 @@ static MOO_INLINE int await_semaphore (moo_t* moo, moo_oop_semaphore_t sem)
 		MOO_ASSERT (moo, moo->processor->active != proc);
 	}
 
+#if 0
 	return 0;
+#endif
 }
 
-static MOO_INLINE moo_oop_t await_semaphore_group (moo_t* moo, moo_oop_semaphore_group_t semgrp)
+static MOO_INLINE moo_oop_t await_semaphore_group (moo_t* moo, moo_oop_semaphore_group_t semgrp, const moo_ntime_t* tmout)
 {
 /* TODO: support timeout and wait all */
 	/* wait for one of semaphores in the group to be signaled */
@@ -859,13 +867,22 @@ static MOO_INLINE moo_oop_t await_semaphore_group (moo_t* moo, moo_oop_semaphore
 			count--;
 			sem->count = MOO_SMOOI_TO_OOP(count);
 			semgrp->pos = MOO_SMOOI_TO_OOP(sempos); /* position of the last inspected semaphore */
-			semgrp->sigsem = sem; /* remember the last signaled semaphore */
 			return (moo_oop_t)sem;
 		}
 	}
 
 	/* no semaphores have been signaled. suspend the current process
 	 * until the at least one of them is signaled */
+
+#if 0
+	if (tmout)
+	{
+		/* create an internal semaphore for timeout signaling */
+/* TODO: */
+		if (add_to_sem_heap (moo, tmout_sem) <= -1) return MOO_PF_HARD_FAILURE;
+	}
+#endif
+
 	proc = moo->processor->active;
 
 	/* suspend the active process */
@@ -2471,22 +2488,25 @@ static moo_pfrc_t pf_semaphore_wait (moo_t* moo, moo_ooi_t nargs)
 	 * await_semaphore() may switch the active process and the stack
 	 * manipulation macros target at the active process. i'm not supposed
 	 * to change the return value of a new active process. */
-
 	MOO_STACK_SETRETTORCV (moo, nargs);
 
+#if 0
 	if (await_semaphore (moo, (moo_oop_semaphore_t)rcv) <= -1)
 	{
 		/* i must switch the top because the return value has been set already */
 		MOO_STACK_SETTOP (moo, MOO_ERROR_TO_OOP(moo->errnum));
 		return MOO_PF_SUCCESS;
 	}
+#else
+	await_semaphore (moo, (moo_oop_semaphore_t)rcv);
+#endif
 
 	return MOO_PF_SUCCESS;
 }
 
 static moo_pfrc_t pf_semaphore_group_wait (moo_t* moo, moo_ooi_t nargs)
 {
-	moo_oop_t rcv;
+	moo_oop_t rcv, sem;
 
 	rcv = MOO_STACK_GETRCV(moo, nargs);
 	MOO_PF_CHECK_RCV (moo, MOO_CLASSOF(moo,rcv) == moo->_semaphore_group);
@@ -2500,7 +2520,17 @@ static moo_pfrc_t pf_semaphore_group_wait (moo_t* moo, moo_ooi_t nargs)
 	 * the stack from this moment on. */
 	MOO_STACK_SETRETTORCV (moo, nargs);
 
-	await_semaphore_group (moo, (moo_oop_semaphore_group_t)rcv);
+	sem = await_semaphore_group (moo, (moo_oop_semaphore_group_t)rcv, MOO_NULL);
+	if (sem != moo->_nil)
+	{
+		/* there was a singaled semaphore. the active process won't get
+		 * suspended. change the return value of the current process
+		 * forcibly to the signaled semaphore */
+		MOO_STACK_SETTOP (moo, sem);
+	}
+
+	/* the return value will get changed to an actual semaphore signaled
+	 * when the semaphore is signaled. see signal_semaphore() */
 	return MOO_PF_SUCCESS;
 }
 
@@ -4763,7 +4793,7 @@ static MOO_INLINE int switch_process_if_needed (moo_t* moo)
 			do
 			{
 				vm_gettime (moo, &now);
-				now.sec += 3;
+				now.sec += 3; /* TODO: use a configured value? */
 				vm_muxwait (moo, &now);
 			}
 			while (moo->processor->active == moo->nil_process && !moo->abort_req);

moo/lib/moo.h

@@ -752,7 +752,7 @@ typedef struct moo_process_t* moo_oop_process_t;
 typedef struct moo_semaphore_t moo_semaphore_t;
 typedef struct moo_semaphore_t* moo_oop_semaphore_t;
 
-#define MOO_SEMAPHORE_GROUP_NAMED_INSTVARS 6
+#define MOO_SEMAPHORE_GROUP_NAMED_INSTVARS 5
 typedef struct moo_semaphore_group_t moo_semaphore_group_t;
 typedef struct moo_semaphore_group_t* moo_oop_semaphore_group_t;
 
@@ -833,7 +833,6 @@ struct moo_semaphore_group_t
 	moo_oop_t size; /* SmallInteger */
 	moo_oop_t pos; /* current processing position */
 	moo_oop_oop_t semarr; /* Array of Semaphores */
-	moo_oop_semaphore_t sigsem; /* Last signaled semaphore */
 };
 
 #define MOO_PROCESS_SCHEDULER_NAMED_INSTVARS 9