MT#65612 RegThread: use `run_cond.wait_for()` instead of sleeping

Instead of blindly sleeping, use the `run_cond.wait_for()`
for the case, when AmThread sends `.notify_all()` upon stopping.
Hence we don't have to block the whole thread for 10 seconds if
suddenly the `stop()` is requested by AmThread at the very beginning
of the sleep.

Add a dedicated `RegThread::wait_or_stop()` wrapper to handle this.

Also differentiate whether the `RegThread::wait_or_stop()` returns
due to timer exceed or there was an actual thread stop requested.
Act accordingly during the `run()` execution.

Change-Id: I1e603c462af983e633c811d10ed2d0ac506f46d3

apps/reg_agent/RegistrationAgent.cpp

@@ -31,6 +31,7 @@
 #include "sems.h"
 #include "log.h"
 
+#include <chrono>
 #include <unistd.h>
 #include "ampi/SIPRegistrarClientAPI.h"
 
@@ -115,7 +116,6 @@ AmSession* RegistrationAgentFactory::onInvite(const AmSipRequest& req, const str
   return NULL;
 }
 
-
 void RegThread::add_reg(const RegInfo& ri) {
   registrations.push_back(ri);
 }
@@ -176,12 +176,30 @@ bool RegThread::check_registration(const RegInfo& ri) {
   return false;
 }
 
+/**
+ * true  => stop was requested
+ * false => timeout elapsed normally
+ */
+bool RegThread::wait_or_stop(unsigned int seconds)
+{
+  /* it should use the same mutex that protects the condition */
+  std::unique_lock<std::mutex> l(run_mut);
+
+  /* wait for `run_cond.notify_all()` / `notify_one()` or timeout */
+  return run_cond.wait_for(
+    l,
+    std::chrono::seconds(seconds),
+    [this] { return stop_requested_unlocked(); });
+}
 
 void RegThread::run() {
   DBG("registrar client started.\n");
 
-  /* wait for sems to completely start up */
-  sleep(2);
+  /* wait for sems to completely start up, but allow clean shutdown */
+  if (wait_or_stop(2)) {
+    DBG("Stop was requested, return..\n");
+    return;
+  }
 
   while (!stop_requested())
   {
@@ -196,7 +214,11 @@ void RegThread::run() {
         create_registration(*it);
       }
     }
-    sleep(10); /* 10 seconds */
+    /* wait until next retry interval, or exit immediately on stop() */
+    if (wait_or_stop(10)) {
+      DBG("Stop was requested, return..\n");
+      break;
+    }
   }
 }
 

apps/reg_agent/RegistrationAgent.h

@@ -57,6 +57,7 @@ class RegThread : public AmThread {
   void run();
   void on_stop();
  public:
+  bool wait_or_stop(unsigned int seconds);
   void add_reg(const RegInfo& ri);
   void postEvent(AmEvent* ev);
 };