From: Lou Woods <lou.wo...@oarcorp.com>
Changed the POSIX message queue thread release order from
FIFO to priority per the Open Group Specification.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html
closes #3791.
---
cpukit/posix/src/mqueueopen.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/cpukit/posix/src/mqueueopen.c b/cpukit/posix/src/mqueueopen.c
index 4bb8025..f613002 100644
--- a/cpukit/posix/src/mqueueopen.c
+++ b/cpukit/posix/src/mqueueopen.c
@@ -90,16 +90,22 @@ static mqd_t _POSIX_Message_queue_Create(
the_mq->oflag = oflag;
/*
- * NOTE: That thread blocking discipline should be based on the
- * current scheduling policy.
+ * NOTE: That thread blocking discipline is priority based on text from the
+ * Open Group cited below. This is not a new requirement and was present
+ * in the 1997 specification.
*
- * Joel: Cite POSIX or OpenGroup on above statement so we can determine
- * if it is a real requirement.
+ * mq_receive() Description Paragraph 4:
+ * If more than one thread is waiting to receive a message when a message
+ * arrives at an empty queue and the Priority Scheduling option is
+ * supported, then the thread of highest priority that has been waiting
+ * the longest shall be selected to receive the message.
+ * http://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html
+ * The Open Group Base Specifications Issue 7, 2018 edition
*/
if (
!_CORE_message_queue_Initialize(
&the_mq->Message_queue,
- CORE_MESSAGE_QUEUE_DISCIPLINES_FIFO,
+ CORE_MESSAGE_QUEUE_DISCIPLINES_PRIORITY,
attr->mq_maxmsg,
attr->mq_msgsize
)
--
1.8.3.1
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