From a63f6ea6caca9a2ab5bab2f44f7bd1caba816315 Mon Sep 17 00:00:00 2001
From: Bin Qian <bin.qian@windriver.com>
Date: Fri, 12 Oct 2018 08:34:36 -0400
Subject: [PATCH] Add idle time to worker thread

Adding 50ms idle time in worker thread loop.
This is to fix sm taking 100% cpu for a busy loop.

Closes-Bug 1797438

Change-Id: Ia41acfab86c0188ceb5c80822010376977c6fc74
Signed-off-by: Bin Qian <bin.qian@windriver.com>
---
 .../sm-1.0.0/src/sm_worker_thread.cpp         | 20 ++++++++++++++++---
 service-mgmt/sm-1.0.0/src/sm_worker_thread.h  |  1 -
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/service-mgmt/sm-1.0.0/src/sm_worker_thread.cpp b/service-mgmt/sm-1.0.0/src/sm_worker_thread.cpp
index 8d5daeb0..93821548 100644
--- a/service-mgmt/sm-1.0.0/src/sm_worker_thread.cpp
+++ b/service-mgmt/sm-1.0.0/src/sm_worker_thread.cpp
@@ -8,6 +8,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
+#include <time.h>
 #include "sm_util_types.h"
 #include "sm_debug.h"
 
@@ -84,7 +85,7 @@ SmErrorT SmWorkerThread::go()
     }
 
     this->_thread_created = true;
-    if( 0 != sem_init(&this->_sem, 0, MAX_QUEUED_ACTIONS) )
+    if( 0 != sem_init(&this->_sem, 0, 0) )
     {
         DPRINTFE("Cannot init semaphore");
         return SM_FAILED;
@@ -147,9 +148,22 @@ void SmWorkerThread::add_priority_action(SmAction& action)
 // ****************************************************************************
 void SmWorkerThread::thread_run()
 {
+    int wait_interval_ns = 50*1000000; //50 ms
+    int ns_to_sec = 1000000000;
+    struct timespec wait_time;
+
     while(this->_goon)
     {
-        if(0 == sem_trywait(&this->_sem))
+        clock_gettime(CLOCK_REALTIME, &wait_time);
+
+        wait_time.tv_nsec += wait_interval_ns;
+        if(wait_time.tv_nsec > ns_to_sec -1)
+        {
+            wait_time.tv_nsec -= ns_to_sec;
+            wait_time.tv_sec ++;
+        }
+
+        if(0 ==  sem_timedwait(&this->_sem, &wait_time))
         {
             SmAction* action = NULL;
             if(!this->_priority_queue.empty())
@@ -165,7 +179,7 @@ void SmWorkerThread::thread_run()
             {
                 action->action();
             }
-        }else if(EAGAIN != errno)
+        }else if(ETIMEDOUT != errno)
         {
             DPRINTFE("Semaphore wait failed. Error %d", errno);
         }
diff --git a/service-mgmt/sm-1.0.0/src/sm_worker_thread.h b/service-mgmt/sm-1.0.0/src/sm_worker_thread.h
index 49ed2547..06028a69 100644
--- a/service-mgmt/sm-1.0.0/src/sm_worker_thread.h
+++ b/service-mgmt/sm-1.0.0/src/sm_worker_thread.h
@@ -11,7 +11,6 @@
 #include <pthread.h>
 #include <semaphore.h>
 
-#define MAX_QUEUED_ACTIONS 24
 // ****************************************************************************
 // SmAction interface, action to process in a worker thread
 // ****************************************************************************