From a570a5c17f089c383944c5e8eb8c63bec85bb317 Mon Sep 17 00:00:00 2001
From: cvs2svn <Unknown>
Date: Thu, 1 May 2003 23:18:33 +0000
Subject: [PATCH] This commit was manufactured by cvs2svn to create branch
 'B3.13'.

---
 src/ca/caEventRate.cpp | 134 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 src/ca/caEventRate.cpp

diff --git a/src/ca/caEventRate.cpp b/src/ca/caEventRate.cpp
new file mode 100644
index 000000000..be8f30360
--- /dev/null
+++ b/src/ca/caEventRate.cpp
@@ -0,0 +1,134 @@
+/*************************************************************************\
+* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
+*     National Laboratory.
+* Copyright (c) 2002 The Regents of the University of California, as
+*     Operator of Los Alamos National Laboratory.
+* EPICS BASE Versions 3.13.7
+* and higher are distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution. 
+\*************************************************************************/
+
+#include <stdio.h>
+#include <limits.h>
+#include <math.h>
+
+#include "cadef.h"
+#include "dbDefs.h"
+#include "epicsTime.h"
+#include "errlog.h"
+
+/*
+ * event_handler()
+ */
+extern "C" void eventCallBack ( struct event_handler_args args )
+{
+    unsigned *pCount = static_cast < unsigned * > ( args.usr );
+    (*pCount)++;
+}
+
+/*
+ * caEventRate ()
+ */
+void caEventRate ( const char *pName, unsigned count )
+{
+    unsigned i;
+    static const double initialSamplePeriod = 1.0;
+    static const double maxSamplePeriod = 60.0 * 5.0;
+
+    printf ( "Connecting to CA Channel \"%s\" %u times.", 
+                pName, count );
+    fflush ( stdout );
+
+    chid * pChidTable = new chid [ count ];
+    assert ( pChidTable );
+    epicsTime begin = epicsTime::getCurrent ();
+    for ( i = 0u; i < count; i++ ) {
+        int status = ca_search ( pName,  & pChidTable[i] );
+        SEVCHK ( status, NULL );
+    }
+
+    int status = ca_pend_io ( 10000.0 );
+    if ( status != ECA_NORMAL ) {
+        fprintf ( stderr, " not found.\n" );
+        return;
+    }
+    epicsTime end = epicsTime::getCurrent ();
+
+    printf ( " done(%f sec).\n", end - begin );
+
+    printf ( "Subscribing %u times.", count );
+    fflush ( stdout );
+
+    unsigned eventCount = 0u;
+    begin = epicsTime::getCurrent ();
+    for ( i = 0u; i < count; i++ ) {
+        status = ca_add_event ( DBR_FLOAT, 
+            pChidTable[i], eventCallBack, &eventCount, NULL);
+        SEVCHK ( status, __FILE__ );
+    }
+
+    status = ca_flush_io ();
+    SEVCHK ( status, __FILE__ );
+
+    end = epicsTime::getCurrent ();
+
+    printf ( " done(%f sec).\n", end - begin );
+        
+    printf ( "Waiting for initial value events." );
+    fflush ( stdout );
+
+    // let the first one go by 
+    begin = epicsTime::getCurrent ();
+    while ( eventCount < count ) {
+        status = ca_pend_event ( 0.01 );
+        if ( status != ECA_TIMEOUT ) {
+            SEVCHK ( status, NULL );
+        }
+    }
+    end = epicsTime::getCurrent ();
+
+    printf ( " done(%f sec).\n", end - begin );
+
+    double samplePeriod = initialSamplePeriod;
+    double X = 0.0;
+    double XX = 0.0;
+    unsigned N = 0u;
+    while ( true ) {
+        unsigned nEvents, lastEventCount, curEventCount;
+
+        epicsTime begin = epicsTime::getCurrent ();
+        lastEventCount = eventCount;
+        status = ca_pend_event ( samplePeriod );
+        curEventCount = eventCount;
+        epicsTime end = epicsTime::getCurrent ();
+        if ( status != ECA_TIMEOUT ) {
+            SEVCHK ( status, NULL );
+        }
+
+        if ( curEventCount >= lastEventCount ) {
+            nEvents = curEventCount - lastEventCount;
+        }
+        else {
+            nEvents = ( UINT_MAX - lastEventCount ) + curEventCount + 1u;
+        }
+
+        N++;
+
+        double period = end - begin;
+        double Hz = nEvents / period;
+
+        X += Hz;
+        XX += Hz * Hz;
+
+        double mean = X / N;
+        double stdDev = sqrt ( XX / N - mean * mean );
+
+        printf ( "CA Event Rate (Hz): current %g mean %g std dev %g\n", 
+            Hz, mean, stdDev );
+
+        if ( samplePeriod < maxSamplePeriod ) {
+            samplePeriod += samplePeriod;
+        }
+    }
+}
+