fix 'pva' provider registration during static linking

Move 'pva' provider registration into registry singleton
construction to ensure that it is done.

src/factory/ChannelAccessFactory.cpp

@@ -9,6 +9,7 @@
 
 #include <osiSock.h>
 #include <epicsThread.h>
+#include <epicsSignal.h>
 
 #include <pv/lock.h>
 #include <pv/noDefaultMethods.h>
@@ -18,6 +19,7 @@
 
 #define epicsExportSharedSymbols
 #include <pv/pvAccess.h>
+#include <pv/clientContextImpl.h>
 #include <pv/factory.h>
 #include "pv/codec.h"
 #include <pv/serverContextImpl.h>
@@ -161,7 +163,12 @@ epicsThreadOnceId providerRegOnce = EPICS_THREAD_ONCE_INIT;
 
 void providerRegInit(void*)
 {
+    epicsSignalInstallSigAlarmIgnore();
+    epicsSignalInstallSigPipeIgnore();
+
     providerRegGbl = new providerRegGbl_t;
+    providerRegGbl->clients->add("pva", createClientProvider);
+
     registerRefCounter("ServerContextImpl", &ServerContextImpl::num_instances);
     registerRefCounter("ServerChannel", &ServerChannel::num_instances);
     registerRefCounter("BlockingTCPTransportCodec", &detail::BlockingTCPTransportCodec::num_instances);

src/pva/clientFactory.cpp

@@ -6,60 +6,17 @@
 
 #include <string>
 
-#include <epicsSignal.h>
-#include <epicsExit.h>
 #include <pv/lock.h>
 
 #define epicsExportSharedSymbols
-#include <pv/logger.h>
 #include <pv/clientFactory.h>
-#include <pv/clientContextImpl.h>
 
 using namespace epics::pvData;
 using namespace epics::pvAccess;
 
-static
-void pva_factory_cleanup(void*)
-{
-    try {
-        ChannelProviderRegistry::clients()->remove("pva");
-    } catch(std::exception& e) {
-        LOG(logLevelWarn, "Error when unregister \"pva\" factory");
-    }
-}
-
 void ClientFactory::start()
 {
-    epicsSignalInstallSigAlarmIgnore();
-    epicsSignalInstallSigPipeIgnore();
-
-    if(ChannelProviderRegistry::clients()->add("pva", createClientProvider, false))
-        epicsAtExit(&pva_factory_cleanup, NULL);
+    // 'pva' registration in ChannelAccessFactory.cpp
 }
 
-void ClientFactory::stop()
-{
-    // unregister now done with exit hook
-}
-
-// automatically register on load
-namespace {
-struct pvaloader
-{
-    pvaloader() {
-        ClientFactory::start();
-    }
-} pvaloaderinstance;
-} // namespace
-
-// perhaps useful during dynamic loading?
-extern "C" {
-void registerClientProvider_pva()
-{
-    try {
-        ClientFactory::start();
-    } catch(std::exception& e){
-        std::cerr<<"Error loading pva: "<<e.what()<<"\n";
-    }
-}
-} // extern "C"
+void ClientFactory::stop() {}