fixed situations where local host name cache is repatedly created and destroyed

src/ca/cac.cpp

@@ -126,6 +126,7 @@ cac::cac (
     epicsMutex & mutualExclusionIn, 
     epicsMutex & callbackControlIn, 
     cacContextNotify & notifyIn ) :
+    _refLocalHostName ( localHostNameCache.getReference () ),
     programBeginTime ( epicsTime::getCurrent() ),
     connTMO ( CA_CONN_VERIFY_PERIOD ),
     mutex ( mutualExclusionIn ),

src/ca/cac.h

@@ -36,6 +36,7 @@
 #include "epicsTimer.h"
 #include "epicsEvent.h"
 #include "freeList.h"
+#include "localHostName.h"
 
 #ifdef cach_restore_epicsExportSharedSymbols
 #   define epicsExportSharedSymbols
@@ -212,8 +213,10 @@ public:
     static unsigned highestPriorityLevelBelow ( unsigned priority );
     void destroyIIU ( tcpiiu & iiu ); 
 
+    const char * pLocalHostName ();
+    
 private:
-    localHostName hostNameCache;
+    epicsSingleton < localHostName > :: reference _refLocalHostName;
     chronIntIdResTable < nciu > chanTable;
     //
     // !!!! There is at this point no good reason
@@ -434,5 +437,10 @@ inline nciu * cac::lookupChannel (
     return this->chanTable.lookup ( idIn );
 }
 
+inline const char * cac :: pLocalHostName ()
+{
+    return _refLocalHostName->pointer ();
+}
+
 #endif // ifdef cach
 

src/ca/cacChannel.cpp

@@ -32,6 +32,18 @@
 #include "localHostName.h"
 #include "cacIO.h"
 
+class CACChannelPrivate {
+public:
+    CACChannelPrivate ();
+    unsigned getHostName ( char * pBuf, unsigned bufLength );
+    const char * pHostName ();
+private:
+    epicsSingleton < localHostName > :: reference
+        _refLocalHostName;
+};
+    
+static epicsThreadOnceId cacChannelIdOnce = EPICS_THREAD_ONCE_INIT;
+
 const cacChannel::priLev cacChannel::priorityMax = 99u;
 const cacChannel::priLev cacChannel::priorityMin = 0u;
 const cacChannel::priLev cacChannel::priorityDefault = priorityMin;
@@ -80,15 +92,40 @@ bool cacChannel::connected (
     return true;
 }
 
+CACChannelPrivate :: 
+    CACChannelPrivate() :
+    _refLocalHostName ( localHostNameCache.getReference () )
+{
+}
+
+inline unsigned CACChannelPrivate :: 
+    getHostName ( char * pBuf, unsigned bufLength )
+{
+    return _refLocalHostName->getName ( pBuf, bufLength );
+}
+    
+inline const char * CACChannelPrivate :: 
+    pHostName ()
+{
+    return _refLocalHostName->pointer ();
+}
+
+static CACChannelPrivate * pCACChannelPrivate = 0;
+    
+// runs once only for each process
+extern "C" void cacChannelSetup ( void * )
+{
+    pCACChannelPrivate = new CACChannelPrivate ();
+}
+
 // the default is to assume that it is a locally hosted channel
 unsigned cacChannel::getHostName ( 
     epicsGuard < epicsMutex > &,
     char * pBuf, unsigned bufLength ) const throw ()
 {
     if ( bufLength ) {
-        epicsSingleton < localHostName >::reference 
-                ref ( localHostNameAtLoadTime.getReference () );
-        return ref->getName ( pBuf, bufLength );
+        epicsThreadOnce ( & cacChannelIdOnce, cacChannelSetup, 0);
+        return pCACChannelPrivate->getHostName ( pBuf, bufLength );
     }
     return 0u;
 }
@@ -97,9 +134,8 @@ unsigned cacChannel::getHostName (
 const char * cacChannel::pHostName (
     epicsGuard < epicsMutex > & ) const throw ()
 {
-    epicsSingleton < localHostName >::reference 
-            ref ( localHostNameAtLoadTime.getReference () );
-    return ref->pointer ();
+    epicsThreadOnce ( & cacChannelIdOnce, cacChannelSetup, 0);
+    return pCACChannelPrivate->pHostName ();
 }
 
 cacContext::~cacContext () {}

src/ca/cacIO.h

@@ -56,7 +56,6 @@
 #include "epicsMutex.h"
 #include "epicsGuard.h"
 #include "epicsThread.h"
-#include "epicsSingleton.h"
 
 #ifdef cacIOh_restore_epicsExportSharedSymbols
 #   define epicsExportSharedSymbols

src/ca/localHostName.cpp

@@ -23,7 +23,7 @@
 
 #include "localHostName.h"
 
-epicsSingleton < localHostName > localHostNameAtLoadTime;
+epicsSingleton < localHostName > localHostNameCache;
 
 localHostName::localHostName () :
     attachedToSockLib ( osiSockAttach () != 0 ), length ( 0u )

src/ca/localHostName.h

@@ -48,7 +48,7 @@ private:
     char cache [128];
 };
 
-extern epicsSingleton < localHostName > localHostNameAtLoadTime;
+extern epicsSingleton < localHostName > localHostNameCache;
 
 inline unsigned localHostName::nameLength () const
 {

src/ca/tcpiiu.cpp

@@ -1259,10 +1259,8 @@ void tcpiiu::hostNameSetRequest ( epicsGuard < epicsMutex > & guard ) // X aCC 4
     if ( ! CA_V41 ( this->minorProtocolVersion ) ) {
         return;
     }
-
-    epicsSingleton < localHostName >::reference 
-            ref ( localHostNameAtLoadTime.getReference () );
-    const char * pName = ref->pointer ();
+    
+    const char * pName = this->cacRef.pLocalHostName ();
     unsigned size = strlen ( pName ) + 1u;
     unsigned postSize = CA_MESSAGE_ALIGN ( size );
     assert ( postSize < 0xffff );

src/ca/virtualCircuit.h

@@ -51,7 +51,6 @@ struct caHdrLargeArray {
     ca_uint16_t m_cmmd;         // operation to be performed 
 };
 
-class hostNameCache;
 class ipAddrToAsciiEngine;
 
 class tcpRecvThread : private epicsThreadRunable {