installed event rate test

src/ca/caEventRate.cpp

@@ -0,0 +1,78 @@
+
+
+#include "cadef.h"
+
+#include <stdio.h>
+#include <limits.h>
+
+#include "cadef.h"
+#include "dbDefs.h"
+#include "tsStamp.h"
+
+/*
+ * event_handler()
+ */
+void eventCallBack ( struct event_handler_args args )
+{
+    unsigned *pCount = static_cast < unsigned * > ( args.usr );
+    (*pCount)++;
+}
+
+
+/*
+ * cam ()
+ */
+void caEventRate ( const char *pName )
+{
+    static const double initialSamplePeriod = 1.0;
+    static const double maxSamplePeriod = 60.0;
+
+    chid chan;
+    int status = ca_search ( pName,  &chan );
+    SEVCHK(status, NULL);
+
+    unsigned eventCount = 0u;
+    status = ca_add_event ( DBR_FLOAT, chan, eventCallBack, &eventCount, NULL);
+    SEVCHK ( status, __FILE__ );
+
+    status = ca_pend_io ( 10.0 );
+    if ( status != ECA_NORMAL ) {
+        printf ( "%s not found\n", pName );
+        return;
+    }
+
+    // let the first one go by 
+    while ( eventCount < 1u ) {
+        status = ca_pend_event ( 0.01 );
+        if ( status != ECA_TIMEOUT ) {
+            SEVCHK ( status, NULL );
+        }
+    }
+
+    double samplePeriod = initialSamplePeriod;
+    while ( true ) {
+        unsigned nEvents, lastEventCount, curEventCount;
+
+        lastEventCount = eventCount;
+        status = ca_pend_event ( samplePeriod );
+        curEventCount = eventCount;
+        if ( status != ECA_TIMEOUT ) {
+            SEVCHK ( status, NULL );
+        }
+
+        if ( curEventCount >= lastEventCount ) {
+            nEvents = curEventCount - lastEventCount;
+        }
+        else {
+            nEvents = ( UINT_MAX - lastEventCount ) + curEventCount +1u;
+        }
+
+        printf ( "CA Channel \"%s\" is producing %g subscription update events per second.\n", 
+            pName, nEvents / samplePeriod );
+
+        if ( samplePeriod < maxSamplePeriod ) {
+            samplePeriod += samplePeriod;
+        }
+    }
+}
+