1 files changed, 38 insertions, 32 deletions

diff --git a/src/core/msgqueue.c b/src/core/msgqueue.c
index efa0bb72..41127c50 100644
--- a/src/core/msgqueue.c
+++ b/src/core/msgqueue.c
@@ -26,6 +26,7 @@ struct nni_msgqueue {
 	int		mq_put;
 	int		mq_closed;
 	int		mq_rwait;       // readers waiting (unbuffered)
+	int		mq_wwait;
 	nni_msg **	mq_msgs;
 };
 
@@ -136,6 +137,8 @@ int
 nni_msgqueue_put_impl(nni_msgqueue *mq, nni_msg *msg,
     nni_time expire, nni_signal *signal)
 {
+	int rv;
+
 	nni_mutex_enter(&mq->mq_lock);
 
 	for (;;) {
@@ -151,7 +154,9 @@ nni_msgqueue_put_impl(nni_msgqueue *mq, nni_msg *msg,
 		}
 
 		// unbuffered, room for one, and a reader waiting?
-		if (mq->mq_rwait && (mq->mq_len == mq->mq_cap)) {
+		if (mq->mq_rwait &&
+		    (mq->mq_cap == 0) &&
+		    (mq->mq_len == mq->mq_cap)) {
 			break;
 		}
 
@@ -167,14 +172,14 @@ nni_msgqueue_put_impl(nni_msgqueue *mq, nni_msg *msg,
 			return (NNG_EAGAIN);
 		}
 
-		// timedout?
-		if (expire <= nni_clock()) {
+		// not writeable, so wait until something changes
+		mq->mq_wwait++;
+		rv = nni_cond_waituntil(&mq->mq_writeable, expire);
+		mq->mq_wwait--;
+		if (rv == NNG_ETIMEDOUT) {
 			nni_mutex_exit(&mq->mq_lock);
 			return (NNG_ETIMEDOUT);
 		}
-
-		// not writeable, so wait until something changes
-		(void) nni_cond_waituntil(&mq->mq_writeable, expire);
 	}
 
 	// Writeable!  Yay!!
@@ -185,8 +190,8 @@ nni_msgqueue_put_impl(nni_msgqueue *mq, nni_msg *msg,
 		mq->mq_put = 0;
 	}
 	mq->mq_len++;
-	if (mq->mq_len == 1) {
-		nni_cond_signal(&mq->mq_readable);
+	if (mq->mq_rwait) {
+		nni_cond_broadcast(&mq->mq_readable);
 	}
 	nni_mutex_exit(&mq->mq_lock);
 	return (0);
@@ -197,49 +202,50 @@ static int
 nni_msgqueue_get_impl(nni_msgqueue *mq, nni_msg **msgp,
     nni_time expire, nni_signal *signal)
 {
+	int rv;
+
 	nni_mutex_enter(&mq->mq_lock);
 
-	while ((!mq->mq_closed) && (mq->mq_len == 0) && (*signal == 0)) {
-		if (expire <= nni_clock()) {
-			nni_mutex_exit(&mq->mq_lock);
-			if (expire == NNI_TIME_ZERO) {
-				return (NNG_EAGAIN);
-			}
-			return (NNG_ETIMEDOUT);
-		}
-		mq->mq_rwait++;
-		if (mq->mq_cap == 0) {
-			// If a writer is blocked, unblock him.
-			nni_cond_signal(&mq->mq_writeable);
+	for (;;) {
+		// always prefer to deliver data if its there
+		if (mq->mq_len != 0) {
+			break;
 		}
-		(void) nni_cond_waituntil(&mq->mq_readable, expire);
-		mq->mq_rwait--;
-	}
-
-	// If there is any data left in the message queue, we will still
-	// provide it, so that the reader can drain.
-	if (mq->mq_len == 0) {
 		if (mq->mq_closed) {
-			nni_cond_signal(&mq->mq_drained);
 			nni_mutex_exit(&mq->mq_lock);
 			return (NNG_ECLOSED);
 		}
-
+		if (expire == NNI_TIME_ZERO) {
+			nni_mutex_exit(&mq->mq_lock);
+			return (NNG_EAGAIN);
+		}
 		if (*signal) {
-			// We are being interrupted.
 			nni_mutex_exit(&mq->mq_lock);
 			return (NNG_EINTR);
 		}
+		if ((mq->mq_cap == 0) & (mq->mq_wwait)) {
+			// let a write waiter know we are ready
+			nni_cond_broadcast(&mq->mq_writeable);
+		}
+		mq->mq_rwait++;
+		rv = nni_cond_waituntil(&mq->mq_readable, expire);
+		mq->mq_rwait--;
+		if (rv == NNG_ETIMEDOUT) {
+			nni_mutex_exit(&mq->mq_lock);
+			return (NNG_ETIMEDOUT);
+		}
 	}
 
+	// Readable!  Yay!!
+
 	*msgp = mq->mq_msgs[mq->mq_get];
 	mq->mq_len--;
 	mq->mq_get++;
 	if (mq->mq_get == mq->mq_alloc) {
 		mq->mq_get = 0;
 	}
-	if (mq->mq_len == (mq->mq_cap - 1)) {
-		nni_cond_signal(&mq->mq_writeable);
+	if (mq->mq_wwait) {
+		nni_cond_broadcast(&mq->mq_writeable);
 	}
 	nni_mutex_exit(&mq->mq_lock);
 	return (0);