From c4f5756c82d7bbb5a5e70d9aad0d2c497d956a17 Mon Sep 17 00:00:00 2001
From: Lee Ballard <ballle98@gmail.com>
Date: Mon, 11 Feb 2019 12:23:29 -0600
Subject: [PATCH] #8: replace busy polling with pthread_cond_wait

---
 aq_programmer.c | 51 ++++++++++++++++++++++++++++++++-----------------
 aqualink.h      |  4 ++++
 aqualinkd.c     |  4 ++++
 3 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/aq_programmer.c b/aq_programmer.c
index db31647..52c196c 100644
--- a/aq_programmer.c
+++ b/aq_programmer.c
@@ -393,24 +393,35 @@ void waitForSingleThreadOrTerminate(struct programmingThreadCtrl *threadCtrl, pr
     pthread_exit(0);
   }
 
-
-
-  // :TODO: use a mutex or semaphore instead of polling
-  while ( (threadCtrl->aq_data->active_thread.thread_id != 0) && ( i++ <= tries) ) {
-    logMessage (LOG_DEBUG, "Thread %d,%p (%s) sleeping, waiting for thread %d,%p (%s) to finish\n",
-                type, &threadCtrl->thread_id, ptypeName(type),
-                threadCtrl->aq_data->active_thread.ptype, threadCtrl->aq_data->active_thread.thread_id, ptypeName(threadCtrl->aq_data->active_thread.ptype));
-    sleep(waitTime);
-  }
   
-  if (i >= tries) {
-    logMessage (LOG_ERR, "Thread %d,%p timeout waiting for thread %d,%p to finish\n",
-                type, &threadCtrl->thread_id, threadCtrl->aq_data->active_thread.ptype,
-                threadCtrl->aq_data->active_thread.thread_id);
-    free(threadCtrl);
-    pthread_exit(0);
-  }
- 
+  int ret;
+  struct timespec max_wait;
+  clock_gettime(CLOCK_REALTIME, &max_wait);
+  max_wait.tv_sec += 30;
+
+  pthread_mutex_lock(&threadCtrl->aq_data->mutex);
+  while (threadCtrl->aq_data->active_thread.thread_id != 0)
+    {
+      logMessage (LOG_DEBUG, "Thread %d,%p (%s) sleeping, waiting for thread %d,%p (%s) to finish\n",
+                  type, &threadCtrl->thread_id, ptypeName(type),
+                  threadCtrl->aq_data->active_thread.ptype, threadCtrl->aq_data->active_thread.thread_id, ptypeName(threadCtrl->aq_data->active_thread.ptype));
+      if ((ret = pthread_cond_timedwait(&threadCtrl->aq_data->thread_finished_cond,
+                                        &threadCtrl->aq_data->mutex, &max_wait)))
+        {
+          logMessage (LOG_ERR, "Thread %d,%p err %s waiting for thread %d,%p to finish\n",
+                      type, &threadCtrl->thread_id, strerror(ret),
+                      threadCtrl->aq_data->active_thread.ptype,
+                      threadCtrl->aq_data->active_thread.thread_id);
+
+          if ((ret = pthread_mutex_unlock(&threadCtrl->aq_data->mutex)))
+            {
+              logMessage (LOG_ERR, "waitForSingleThreadOrTerminate mutex unlock ret %s\n", strerror(ret));
+            }
+          free(threadCtrl);
+          pthread_exit(0);
+        }
+    }
+
   threadCtrl->aq_data->active_thread.thread_id = &threadCtrl->thread_id;
   threadCtrl->aq_data->active_thread.ptype = type;
 
@@ -420,11 +431,14 @@ void waitForSingleThreadOrTerminate(struct programmingThreadCtrl *threadCtrl, pr
               threadCtrl->aq_data->active_thread.ptype,
               threadCtrl->aq_data->active_thread.thread_id,
               ptypeName(threadCtrl->aq_data->active_thread.ptype));
+  pthread_mutex_unlock(&threadCtrl->aq_data->mutex);
 }
 
 void cleanAndTerminateThread(struct programmingThreadCtrl *threadCtrl)
 {
   struct timespec elapsed;
+
+  pthread_mutex_lock(&threadCtrl->aq_data->mutex);
   clock_gettime(CLOCK_REALTIME, &threadCtrl->aq_data->last_active_time);
   timespec_subtract(&elapsed, &threadCtrl->aq_data->last_active_time, &threadCtrl->aq_data->start_active_time);
   logMessage(LOG_DEBUG, "Thread %d,%p (%s) finished in %d.%03ld sec\n",
@@ -437,6 +451,9 @@ void cleanAndTerminateThread(struct programmingThreadCtrl *threadCtrl)
   // delay(500);
   threadCtrl->aq_data->active_thread.thread_id = 0;
   threadCtrl->aq_data->active_thread.ptype = AQP_NULL;
+  pthread_cond_signal(&threadCtrl->aq_data->thread_finished_cond);
+  pthread_mutex_unlock(&threadCtrl->aq_data->mutex);
+
   threadCtrl->thread_id = 0;
   free(threadCtrl);
   pthread_exit(0);
diff --git a/aqualink.h b/aqualink.h
index 9a074b8..fec108e 100644
--- a/aqualink.h
+++ b/aqualink.h
@@ -4,6 +4,8 @@
 
 #include <pthread.h>
 #include <stdbool.h>
+#include <pthread.h>
+
 #include "aq_serial.h"
 #include "aq_programmer.h"
 
@@ -117,6 +119,8 @@ struct aqualinkdata
   //bool ar_swg_connected;
   struct timespec last_active_time;
   struct timespec start_active_time;
+  pthread_mutex_t mutex;
+  pthread_cond_t thread_finished_cond;
 };
 
 
diff --git a/aqualinkd.c b/aqualinkd.c
index 4737f8e..e53f848 100644
--- a/aqualinkd.c
+++ b/aqualinkd.c
@@ -1029,6 +1029,7 @@ void main_loop()
   int i;
   //int delayAckCnt = 0;
 
+
   // NSF need to find a better place to init this.
   //_aqualink_data.aq_command = 0x00;
   _aqualink_data.simulate_panel = false;
@@ -1066,6 +1067,9 @@ void main_loop()
 
   clock_gettime(CLOCK_REALTIME, &_aqualink_data.last_active_time);
 
+  pthread_mutex_init(&_aqualink_data.mutex, NULL);
+  pthread_cond_init(&_aqualink_data.thread_finished_cond, NULL);
+
   if (!start_net_services(&mgr, &_aqualink_data, &_config_parameters))
   {
     logMessage(LOG_ERR, "Can not start webserver on port %s.\n", _config_parameters.socket_port);