Experimental Physics and
Industrial Control System

Hello Margaret,

This is mantis entry 239.

The issue you have discovered occurs only when calling ca_context_create
(a.k.a. ca_task_initialize) from your C++ file scope object's constructor.

The static variable "ca_client_context::defaultServiceInstallMutex" is also
file scope, and this implies that it's constructor along with the
constructor of your device_attr_stubs both run before main() is called.

Which file scope constructor runs first is very C++ compiler implementation
dependent.

Let me know if the attached patch resolves your troubles.

Jeff

cvs diff -u -wb -i -- ca_client_context.cpp oldAccess.h (in directory
D:\users\hill\R3.14.dll_hell_fix\epics\base\src\ca\)
Index: ca_client_context.cpp
===================================================================
RCS file:
/net/phoebus/epicsmgr/cvsroot/epics/base/src/ca/ca_client_context.cpp,v
retrieving revision 1.9.2.18
diff -c -u -w -b -i -r1.9.2.18 ca_client_context.cpp
cvs diff: conflicting specifications of output style
--- ca_client_context.cpp	13 Apr 2005 17:28:13 -0000	1.9.2.18
+++ ca_client_context.cpp	17 Feb 2006 22:22:11 -0000
@@ -47,6 +47,7 @@
 {
     epicsThreadPrivateDelete ( caClientCallbackThreadId );
     caClientCallbackThreadId = 0;
+    delete ca_client_context::pDefaultServiceInstallMutex;
 }
 
 // runs once only for each process
@@ -54,13 +55,14 @@
 {
     caClientCallbackThreadId = epicsThreadPrivateCreate ();
     assert ( caClientCallbackThreadId );
+    ca_client_context::pDefaultServiceInstallMutex = new epicsMutex;
     epicsAtExit ( cacExitHandler,0 );
 }
 
 extern epicsThreadPrivateId caClientContextId;
 
 cacService * ca_client_context::pDefaultService = 0;
-epicsMutex ca_client_context::defaultServiceInstallMutex;
+epicsMutex * ca_client_context::pDefaultServiceInstallMutex;
 
 ca_client_context::ca_client_context ( bool enablePreemptiveCallback ) :
     ca_exception_func ( 0 ), ca_exception_arg ( 0 ), 
@@ -77,9 +79,7 @@
 
     epicsThreadOnce ( & cacOnce, cacOnceFunc, 0 );
 
-    {
-        // this wont consistently work if called from file scope
constructor
-        epicsGuard < epicsMutex > guard (
ca_client_context::defaultServiceInstallMutex );
+    epicsGuard < epicsMutex > guard (
*ca_client_context::pDefaultServiceInstallMutex );
         if ( ca_client_context::pDefaultService ) {
             this->pServiceContext.reset (
                 & ca_client_context::pDefaultService->contextCreate ( 
@@ -88,7 +88,6 @@
         else {
             this->pServiceContext.reset ( new cac ( this->mutex,
this->cbMutex, *this ) );
         }
-    }
 
     this->sock = epicsSocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
     if ( this->sock == INVALID_SOCKET ) {
@@ -734,8 +733,9 @@
 
 void ca_client_context::installDefaultService ( cacService & service )
 {
-    // this wont consistently work if called from file scope constructor
-    epicsGuard < epicsMutex > guard (
ca_client_context::defaultServiceInstallMutex );
+    epicsThreadOnce ( & cacOnce, cacOnceFunc, 0 );
+
+    epicsGuard < epicsMutex > guard (
*ca_client_context::pDefaultServiceInstallMutex );
     if ( ca_client_context::pDefaultService ) {
         throw std::logic_error
             ( "CA in-memory service already installed and can't be
replaced");
Index: oldAccess.h
===================================================================
RCS file: /net/phoebus/epicsmgr/cvsroot/epics/base/src/ca/oldAccess.h,v
retrieving revision 1.47.2.14
diff -c -u -w -b -i -r1.47.2.14 oldAccess.h
cvs diff: conflicting specifications of output style
--- oldAccess.h	19 Oct 2004 20:48:51 -0000	1.47.2.14
+++ oldAccess.h	17 Feb 2006 22:07:21 -0000
@@ -286,6 +286,9 @@
     void operator delete ( void * );
 };
 
+extern "C" void cacOnceFunc ( void * );
+extern "C" void cacExitHandler ( void *);
+
 struct ca_client_context : public cacContextNotify
 {
 public:
@@ -412,8 +415,10 @@
 	ca_client_context ( const ca_client_context & );
 	ca_client_context & operator = ( const ca_client_context & );
 
+	friend void cacOnceFunc ( void * );
+	friend void cacExitHandler ( void *);
     static cacService * pDefaultService;
-    static epicsMutex defaultServiceInstallMutex;
+    static epicsMutex * pDefaultServiceInstallMutex;
 };
 
 int fetchClientContext ( ca_client_context * * ppcac );

***** CVS exited normally with code 1 *****

References:

segmentation fault in ca_task_initialize running in Linux Margaret Votava

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