Field de-duplication performance test

testApp/pv/Makefile

@@ -65,3 +65,6 @@ TESTS += testFieldBuilder
 TESTPROD_HOST += testValueBuilder
 testValueBuilder_SRCS += testValueBuilder.cpp
 TESTS += testValueBuilder
+
+TESTPROD_Linux += performstruct
+performstruct_SRCS += performstruct.cpp

testApp/pv/performstruct.cpp

@@ -0,0 +1,115 @@
+// Attempt to qualtify the effects of de-duplication on the time need to allocate a PVStructure
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+#include <math.h>
+
+#include <testMain.h>
+#include <epicsUnitTest.h>
+
+#include <pv/current_function.h>
+#include <pv/pvData.h>
+#include <pv/standardField.h>
+
+namespace {
+
+namespace pvd = epics::pvData;
+
+struct TimeIt {
+    struct timespec m_start;
+    double sum, sum2;
+    size_t count;
+    TimeIt() { reset(); }
+    void reset() {
+        sum = sum2 = 0.0;
+        count = 0;
+    }
+    void start() {
+        clock_gettime(CLOCK_MONOTONIC, &m_start);
+    }
+    void end() {
+        struct timespec end;
+        clock_gettime(CLOCK_MONOTONIC, &end);
+        double diff = (end.tv_sec-m_start.tv_sec) + (end.tv_nsec-m_start.tv_nsec)*1e-9;
+        sum += diff;
+        sum2 += diff*diff;
+        count++;
+    }
+    void report(const char *unit ="s", double mult=1.0) const {
+        double mean = sum/count;
+        double mean2 = sum2/count;
+        double std = sqrt(mean2 - mean*mean);
+        printf("# %zu sample   %f +- %f %s\n", count, mean/mult, std/mult, unit);
+    }
+};
+
+void buildMiss()
+{
+    testDiag("%s", CURRENT_FUNCTION);
+    TimeIt record;
+
+    pvd::FieldCreatePtr create(pvd::getFieldCreate());
+    pvd::StandardFieldPtr standard(pvd::getStandardField());
+
+    for(size_t i=0; i<1000; i++) {
+        // unique name each time to (partially) defeat caching
+        char buf[10];
+        sprintf(buf, "field%zu", i);
+
+        record.start();
+
+        pvd::FieldConstPtr fld(create->createFieldBuilder()
+                               ->setId(buf)
+                               ->add("value", pvd::pvInt)
+                               ->addNestedStructure(buf)
+                                   ->add("value", pvd::pvString)
+                               ->endNested()
+                               ->add("display", standard->display())
+                               ->createStructure());
+        record.end();
+    }
+
+    record.report("us", 1e-6);
+}
+
+void buildHit()
+{
+    testDiag("%s", CURRENT_FUNCTION);
+    TimeIt record;
+
+    pvd::FieldCreatePtr create(pvd::getFieldCreate());
+    pvd::StandardFieldPtr standard(pvd::getStandardField());
+
+    pvd::FieldConstPtr fld(create->createFieldBuilder()
+                           ->add("value", pvd::pvInt)
+                           ->addNestedStructure("foo")
+                               ->add("field", pvd::pvString)
+                           ->endNested()
+                           ->add("display", standard->display())
+                           ->createStructure());
+
+    for(size_t i=0; i<1000; i++) {
+
+        record.start();
+
+        pvd::FieldConstPtr fld(create->createFieldBuilder()
+                               ->add("value", pvd::pvInt)
+                               ->addNestedStructure("foo")
+                                   ->add("field", pvd::pvString)
+                               ->endNested()
+                               ->add("display", standard->display())
+                               ->createStructure());
+        record.end();
+    }
+
+    record.report("us", 1e-6);
+}
+
+} // namespace
+
+MAIN(performStruct) {
+    testPlan(0);
+    buildMiss();
+    buildHit();
+    return testDone();
+}