ms: Add is_idle() method to GprsMs::Guard

Currently there is no simple way to determine, whether the MS object
protected by a guard will continue to exist after the guard object is
destroyed.

This patch adds a is_idle() method that will return true if the MS
object is just kept by the guard from being idle. In that case, the
MS object would either be deleted or return true for
GprsMs::is_idle() after the guard's destruction, provided that no
TBF attachment took place in between.

Sponsored-by: On-Waves ehf

src/gprs_ms.cpp

@@ -62,6 +62,14 @@ GprsMs::Guard::~Guard()
 		m_ms->unref();
 }
 
+bool GprsMs::Guard::is_idle() const
+{
+	if (!m_ms)
+		return true;
+
+	return !m_ms->m_ul_tbf && !m_ms->m_dl_tbf && m_ms->m_ref == 1;
+}
+
 void GprsMs::timeout(void *priv_)
 {
 	GprsMs *ms = static_cast<GprsMs *>(priv_);

src/gprs_ms.h

@@ -51,6 +51,8 @@ public:
 		Guard(GprsMs *ms);
 		~Guard();
 
+		bool is_idle() const;
+
 		private:
 		GprsMs * const m_ms;
 	};