more getme.cpp

documentation/Doxyfile

@@ -877,7 +877,7 @@ EXCLUDE_SYMBOLS        =
 # that contain example code fragments that are included (see the \include
 # command).
 
-EXAMPLE_PATH           = 
+EXAMPLE_PATH           = ../examples
 
 # If the value of the EXAMPLE_PATH tag contains directories, you can use the
 # EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp and

documentation/Makefile

@@ -1,5 +1,5 @@
 
-all: gen commit
+all: gen
 
 clean:
 	rm -rf doxygen_sqlite3.db html
@@ -7,7 +7,7 @@ clean:
 gen:
 	doxygen
 
-commit:
+commit: gen
 	touch html/.nojekyll
 	./commit-gh.sh documentation/html/ html/.nojekyll html/*.* html/search/*.*
 

documentation/examples.h

@@ -0,0 +1,10 @@
+/**
+
+@page examples_getme Client Get Example
+
+This example demonstrates a client which issues a Get operation on startup,
+and again each time a channel becomes Connected.
+
+@include getme.cpp
+
+*/

documentation/mainpage.h

@@ -12,6 +12,10 @@ See pv/pvAccess.h
 
 See the @ref providers page.
 
+Examples
+
+- @ref examples_getme
+
 */
 
 #endif /* MAINPAGE_H */

examples/getme.cpp

@@ -1,12 +1,23 @@
 
 #include <set>
+#include <vector>
+#include <string>
 #include <exception>
 
+#if !defined(_WIN32)
+#include <signal.h>
+#define USE_SIGNAL
+#endif
+
+#include <epicsExit.h>
 #include <epicsEvent.h>
 
+//! [Headers]
 #include <pv/configuration.h>
 #include <pv/pvAccess.h>
 #include <pv/clientFactory.h>
+#include <pv/caProvider.h>
+//! [Headers]
 
 namespace pvd = epics::pvData;
 namespace pva = epics::pvAccess;
@@ -15,6 +26,19 @@ namespace {
 
 epicsEvent done;
 
+#ifdef USE_SIGNAL
+void alldone(int num)
+{
+    (void)num;
+    done.signal();
+}
+#endif
+
+void onthewayout(void* arg) {
+    (void)arg;
+    std::cout<<"Done\n";
+}
+
 struct ChanReq : public pva::ChannelRequester
 {
     virtual ~ChanReq() {}
@@ -22,7 +46,9 @@ struct ChanReq : public pva::ChannelRequester
     virtual std::string getRequesterName() { return "ChanReq"; }
 
     virtual void channelCreated(const epics::pvData::Status& status,
-                                pva::Channel::shared_pointer const & channel) {
+                                pva::Channel::shared_pointer const & channel)
+    {
+        // called once, recursively during ChannelProvider::createChannel()
         if(!status.isSuccess()) {
             std::cout<<"Oops Connect: "<<status<<"\n";
         } else {
@@ -31,13 +57,15 @@ struct ChanReq : public pva::ChannelRequester
     }
 
     virtual void channelStateChange(pva::Channel::shared_pointer const & channel,
-                                    pva::Channel::ConnectionState connectionState) {
+                                    pva::Channel::ConnectionState connectionState)
+    {
+        // Called for each connect/disconnect event, and on shutdown (destroy)
         switch(connectionState) {
         case pva::Channel::NEVER_CONNECTED:
         case pva::Channel::CONNECTED:
         case pva::Channel::DISCONNECTED:
         case pva::Channel::DESTROYED:
-            std::cout<<channel->getChannelName()<<" "<<pva::Channel::ConnectionStateNames[connectionState]<<"\n";
+            std::cout<<"CHANNEL "<<channel->getChannelName()<<" "<<pva::Channel::ConnectionStateNames[connectionState]<<"\n";
             break;
 
         default:
@@ -57,20 +85,29 @@ struct GetReq : public pva::ChannelGetRequester
         pva::ChannelGet::shared_pointer const & channelGet,
         pvd::Structure::const_shared_pointer const & structure)
     {
+        // Called each time get operation becomes "ready" (channel connected)
         if(status.isSuccess()) {
-            std::cout<<"Get request"<<channelGet->getChannel()->getChannelName()<<"\n";
+            std::cout<<"Get execute "<<channelGet->getChannel()->getChannelName()<<"\n";
+            // can now execute the get operation
             channelGet->get();
         } else {
             std::cout<<"Oops GetConnect: "<<channelGet->getChannel()->getChannelName()<<" "<<status<<"\n";
         }
     }
 
+    virtual void channelDisconnect(bool destroy) {
+        // Called each time operation becomes no "ready" (channel disconnected)
+        // same as channelStateChange() for DISCONNECTED and DESTROYED
+        std::cout<<"Get disconnected\n";
+    }
+
     virtual void getDone(
         const epics::pvData::Status& status,
         pva::ChannelGet::shared_pointer const & channelGet,
         pvd::PVStructure::shared_pointer const & pvStructure,
         pvd::BitSet::shared_pointer const & bitSet)
     {
+        // when execution completes
         if(status.isSuccess()) {
             pvd::PVFieldPtr valfld(pvStructure->getSubField("value"));
             if(!valfld)
@@ -86,33 +123,75 @@ struct GetReq : public pva::ChannelGetRequester
 
 int main(int argc, char *argv[]) {
     try {
-        // an empty structure
-        pvd::PVStructurePtr pvReq(pvd::getPVDataCreate()->createPVStructure(
-                                      pvd::getFieldCreate()->createFieldBuilder()->createStructure()
-                                      ));
+        std::string providerName("pva");
+        typedef std::vector<std::string> pvs_t;
+        pvs_t pvs;
+
+        for(int i=1; i<argc; i++) {
+            if(argv[i][0]=='-') {
+                if(strcmp(argv[i], "-P")==0 || strcmp(argv[i], "--provider")==0) {
+                    if(i<argc-1) {
+                        providerName = argv[i+1];
+                    } else {
+                        std::cerr << "--provider requires value\n";
+                        return 1;
+                    }
+                } else {
+                    std::cerr<<"Unknown argument: "<<argv[i]<<"\n";
+                }
+
+            } else {
+                pvs.push_back(argv[i]);
+            }
+
+        }
+
+        epicsAtExit(&onthewayout, 0);
+
+#ifdef USE_SIGNAL
+        signal(SIGINT, alldone);
+        signal(SIGTERM, alldone);
+        signal(SIGQUIT, alldone);
+#endif
+
+        // build "pvRequest" which asks for all fields
+        pvd::PVStructure::shared_pointer pvReq(pvd::createRequest("field()"));
+
+        // explicitly select configuration from process environment
         pva::Configuration::shared_pointer conf(pva::ConfigurationBuilder()
                                                 .push_env()
                                                 .build());
 
+        // add "pva" provider to registry
         pva::ClientFactory::start();
+        // add "ca" provider to registry
+        pva::ca::CAClientFactory::start();
 
-        pva::ChannelProvider::shared_pointer provider(pva::getChannelProviderRegistry()->createProvider("pva", conf));
+        std::cout<<"Use provider: "<<providerName<<"\n";
+        pva::ChannelProvider::shared_pointer provider(pva::getChannelProviderRegistry()->createProvider(providerName, conf));
         if(!provider)
             throw std::logic_error("pva provider not registered");
 
+        // need to store references to keep get (and channel) from being closed
         typedef std::set<pva::ChannelGet::shared_pointer> gets_t;
         gets_t gets;
 
+        // as we have no channel or operation specific data,
+        // use the same requesters for all PVs
         pva::ChannelRequester::shared_pointer chanreq(new ChanReq);
         pva::ChannelGetRequester::shared_pointer getreq(new GetReq);
 
-        for(int i=1; i<argc; i++) {
-            if(argv[i][0]=='-') continue;
-            pva::Channel::shared_pointer chan(provider->createChannel(argv[i], chanreq));
+        for(pvs_t::const_iterator it=pvs.begin(); it!=pvs.end(); ++it) {
+            const std::string& pv = *it;
+
+            pva::Channel::shared_pointer chan(provider->createChannel(pv, chanreq));
             // if !chan then channelCreated() called with error status
             if(!chan) continue;
 
+            // no need to wait for connection
+
             pva::ChannelGet::shared_pointer op(chan->createChannelGet(getreq, pvReq));
+            // if !op then channelGetConnect() called with error status
             if(!op) continue;
 
             gets.insert(op);