add ticker example

example/ticker.cpp

@@ -0,0 +1,110 @@
+/**
+ * Copyright - See the COPYRIGHT that is included with this distribution.
+ * pvxs is distributed subject to a Software License Agreement found
+ * in file LICENSE that is included with this distribution.
+ */
+/**
+ * Serves a single integer PV which increments at a pre-defined rate.
+ */
+
+#include <iostream>
+
+#include <epicsTime.h>
+#include <epicsStdlib.h>
+#include <epicsEvent.h>
+
+#include <pvxs/sharedpv.h>
+#include <pvxs/server.h>
+#include <pvxs/nt.h>
+#include <pvxs/log.h>
+#include <pvxs/util.h>
+
+using namespace pvxs;
+
+int main(int argc, char* argv[])
+{
+    double delay = 1.0;
+
+    if(argc<=1) {
+        std::cerr<<"Usage: "<<argv[0]<<" <pvname> [rateHz]\n";
+        return 1;
+    }
+
+    if(argc>=3) {
+        double rate = 0.0;
+
+        if(epicsParseDouble(argv[2], &rate, nullptr) || rate<=0.0) {
+            std::cerr<<"Rate must be a positive number, not "<<argv[2]<<"\n";
+            return 1;
+        }
+
+        delay = 1.0/rate;
+    }
+
+    // Read $PVXS_LOG from process environment and update
+    // logging configuration.  eg.
+    //    export PVXS_LOG=*=DEBUG
+    // makes a lot of noise.
+    logger_config_env();
+
+    // Must provide a data type for the mailbox.
+    // Use pre-canned definition of scalar with meta-data
+    Value initial = nt::NTScalar{TypeCode::UInt32}.create();
+
+    // (optional) Provide an initial value
+    initial["value"] = 0u;
+    initial["alarm.severity"] = 0;
+    initial["alarm.status"] = 0;
+    initial["alarm.message"] = "";
+
+    // Actually creating the mailbox PV.
+    // buildMailbox() installs a default onPut() handler which
+    // stores whatever a client sends (subject to our data type).
+    server::SharedPV pv(server::SharedPV::buildReadonly());
+
+    // Associate a data type (and maybe initial value) with this PV
+    pv.open(initial);
+
+    // Build server which will server this PV
+    // Configure using process environment.
+    server::Server serv = server::Config::from_env()
+            .build()
+            .addPV(argv[1], pv);
+
+    // (optional) Print the configuration this server is using
+    // with any auto-address list expanded.
+    std::cout<<"Effective config\n"<<serv.config();
+
+    // event used to signal exit, and for delay timer
+    epicsEvent done;
+
+    // connect to SIGINT/SIGTERM to break from main loop
+    SigInt handle([&done]() {
+        done.trigger();
+    });
+
+    // Start server in background
+    serv.start();
+
+    std::cout<<"Running\n";
+
+    uint32_t count = 0u;
+
+    while(!done.wait(delay)) {
+        auto val = initial.cloneEmpty();
+
+        val["value"] = count++;
+
+        pv.post(std::move(val));
+
+        std::cout<<"Count "<<count<<"\n";
+    }
+
+    // (optional) explicitly stop server.
+    // Implied when 'serv' goes out of scope
+    serv.stop();
+
+    std::cout<<"Done\n";
+
+    return 0;
+}