From bf1eac02dd0e17e7001568ac055811c7f224b69d Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Wed, 3 Jan 2024 22:48:49 +0100
Subject: [PATCH] Scheduler-test: binary search over continuous domain

- textbook implementation
- capture results from visited points
- average results form the last three points to damp statistic fluctuations
---
 tests/vault/gear/stress-test-rig.hpp | 103 +++++++++++++++++++++++++--
 wiki/thinkPad.ichthyo.mm             |  53 +++++++++++++-
 2 files changed, 148 insertions(+), 8 deletions(-)

diff --git a/tests/vault/gear/stress-test-rig.hpp b/tests/vault/gear/stress-test-rig.hpp
index b1573bd31..dc693ecc5 100644
--- a/tests/vault/gear/stress-test-rig.hpp
+++ b/tests/vault/gear/stress-test-rig.hpp
@@ -81,6 +81,7 @@
 #include "vault/gear/scheduler.hpp"
 #include "lib/time/timevalue.hpp"
 //#include "lib/iter-explorer.hpp"
+#include "lib/meta/function.hpp"
 #include "lib/format-string.hpp"
 #include "lib/format-cout.hpp"//////////////////////////TODO RLY?
 //#include "lib/util.hpp"
@@ -99,8 +100,8 @@ namespace gear {
 namespace test {
   
   using util::_Fmt;
-//  using util::min;
-//  using util::max;
+  using util::min;
+  using util::max;
 //  using util::isnil;
 //  using util::limited;
 //  using util::unConst;
@@ -115,7 +116,7 @@ namespace test {
 
 //  using std::string;
 //  using std::function;
-//  using std::make_pair;
+  using std::make_pair;
   using std::make_tuple;
 //  using std::forward;
 //  using std::string;
@@ -130,6 +131,71 @@ namespace test {
   
   namespace stress_test_rig {
     
+    template<class X, class P>
+    struct _ValidateBinarySearchFun
+      {
+        static_assert (not sizeof(P), "Functor unsuitable for binary search. "
+                                      "Expected signature pair<bool,X>(PAR)" );
+      };
+    template<class RES, class PAR>
+    struct _ValidateBinarySearchFun<std::pair<bool,RES>(PAR), PAR>
+      {
+        using Result = RES;
+      };
+    template<class FUN, typename PAR>
+    inline auto
+    make_binarySearchResults()
+    {
+      using Sig  = typename lib::meta::_Fun<FUN>::Sig;
+      using Res  = typename _ValidateBinarySearchFun<Sig,PAR>::Result;
+      using Data = std::vector<std::pair<bool, Res>>;
+      return Data{};
+    }
+    
+    template<class FUN, class CON, typename PAR>
+    inline auto
+    binarySearch_impl (FUN&& fun, CON results, PAR lower, PAR upper, PAR epsilon)
+    {
+      REQUIRE (lower <= upper);
+      while ((upper-lower) >= epsilon)
+        {
+          PAR div = (upper-lower) / 2;
+          results.emplace_back (fun(div));
+          bool hit = results.back().first;
+          if (hit)
+            upper = div;
+          else
+            lower = div;
+        }
+      return results;
+    }
+    
+    template<class FUN, typename PAR>
+    inline auto
+    binarySearch_inner (FUN&& fun, PAR lower, PAR upper, PAR epsilon)
+    {
+      auto results = make_binarySearchResults<FUN,PAR>();
+      return binarySearch_impl(forward<FUN> (fun), results, lower,upper,epsilon);
+    }
+    
+    template<class FUN, typename PAR>
+    inline auto
+    binarySearch_upper (FUN&& fun, PAR lower, PAR upper, PAR epsilon)
+    {
+      REQUIRE (lower <= upper);
+      auto results = make_binarySearchResults<FUN,PAR>();
+      results.emplace_back (fun(upper));
+      bool hit = results.back().first;
+      if (not hit)
+        {// the upper end breaks contract => search above
+          PAR len = (upper-lower);
+          lower = upper - len/10;
+          upper = lower + 14*len/10;
+        }
+      return binarySearch_impl(forward<FUN> (fun), results, lower,upper,epsilon);
+    }
+    
+    
     /**
      * Specific stress test scheme to determine the
      * »breaking point« where the Scheduler starts to slip
@@ -207,7 +273,30 @@ namespace test {
         Res
         conductBinarySearch (FUN&& runTestCase)
           {
-            UNIMPLEMENTED ("invoke a library implementation of binary search");
+            auto results = binarySearch_upper (forward<FUN> (runTestCase), 0.0, CONF::UPPER_STRESS, CONF::EPSILON);
+            uint s = results.size();
+            ENSURE (s >= 2);
+            Res res;
+            auto& [sf,pf,sdev,avgD,avgT,expT] = res;
+            // average data over the last three steps investigated for smoothing
+            uint points = min (results.size(), 3u);
+            for (uint i=results.size()-points; i<results.size(); ++i)
+              {
+                Res resx = results[i].second;
+                pf   += resx.percentOff;
+                sdev += resx.stdDev;
+                avgD += resx.avgDelta;
+                avgT += resx.avgTime;
+                expT += resx.expTime;
+              }
+            pf   /= points;
+            sdev /= points;
+            avgD /= points;
+            avgT /= points;
+            expT /= points;
+            // »breaking point« stress in the middle of the last interval
+            sf = (results[s-1].second.stressFac + results[s-2].second.stressFac) / 2;
+            return res;
           }
         
         
@@ -273,7 +362,7 @@ namespace test {
                                         {
                                           configureTest (testSetup, stressFac);
                                           auto res = runProbes (testSetup, stressFac);
-                                          return make_tuple (decideBreakPoint(res), res);
+                                          return make_pair (decideBreakPoint(res), res);
                                         };
             
             Res res = conductBinarySearch (move (performEvaluation));
@@ -294,7 +383,9 @@ namespace test {
       
       usec LOAD_BASE = 500us;
       uint CONCURRENCY = work::Config::getDefaultComputationCapacity();
-      double FAIL_LIMIT = 2.0;             ///< delta-limit when to count a run as failure
+      double EPSILON      = 0.01;          ///< error bound to abort binary search
+      double UPPER_STRESS = 0.6;           ///< starting point for the upper limit, likely to fail
+      double FAIL_LIMIT   = 2.0;           ///< delta-limit when to count a run as failure
       double TRIGGER_FAIL = 0.55;          ///< %-fact: criterion-1 failures above this rate
       double TRIGGER_SDEV = FAIL_LIMIT;    ///< in ms : criterion-2 standard derivation
       double TRIGGER_DELTA = 2*FAIL_LIMIT; ///< in ms : criterion-3 delta above this limit
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 58bcfc856..ea5cab807 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -107830,11 +107830,60 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node CREATED="1704237555914" ID="ID_1779084715" MODIFIED="1704237568213" TEXT="funktionale Konfigurations-Hooks"/>
 <node CREATED="1704237569280" ID="ID_227955379" MODIFIED="1704237574469" TEXT="Basis-Setup einmischen"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1704243593362" ID="ID_1513298833" MODIFIED="1704243606440" TEXT="Statistik-Berechnung integrieren">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1704243593362" ID="ID_1513298833" MODIFIED="1704316330671" TEXT="Statistik-Berechnung integrieren">
+<icon BUILTIN="button_ok"/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1704243607600" ID="ID_1968188887" MODIFIED="1704243618662" TEXT="Lib-Implementierung: bin&#xe4;re Suche">
 <icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1704316333600" ID="ID_198671243" MODIFIED="1704322903614" TEXT="Basis-Algo">
+<icon BUILTIN="button_ok"/>
+<node CREATED="1704316348241" ID="ID_118215771" MODIFIED="1704316368237" TEXT="Parameter-Range [lower, upper]"/>
+<node CREATED="1704316374393" ID="ID_1441038472" MODIFIED="1704317029516" TEXT="Invariante: test(lower) &#x2261; false &#x2227; test(upper)  &#x2261; true">
+<node BACKGROUND_COLOR="#ccb59b" COLOR="#6e2a38" CREATED="1704316425945" ID="ID_242995900" MODIFIED="1704317035203" TEXT="das wird Eingangs nicht gepr&#xfc;ft">
+<font ITALIC="true" NAME="SansSerif" SIZE="14"/>
+<icon BUILTIN="yes"/>
+</node>
+<node CREATED="1704317043838" ID="ID_1366116745" MODIFIED="1704317054641" TEXT="dann stellt es jede Iteration wieder her"/>
+</node>
+<node CREATED="1704316569022" ID="ID_1489985848" MODIFIED="1704316590391" TEXT="Vorgabe Such-Genauigkeit &#x3b5;">
+<node CREATED="1704316840481" ID="ID_1649502723" MODIFIED="1704316856915" TEXT="solange Intervall gr&#xf6;&#xdf;er, wird geteilt"/>
+<node CREATED="1704316870382" ID="ID_546344675" MODIFIED="1704316917969" TEXT="sonst wird die Intervallmitte zum Ergebnis"/>
+<node CREATED="1704316928158" ID="ID_208081940" MODIFIED="1704316942065" TEXT="&#x27f9; Fehler &lt; &#x3b5;"/>
+</node>
+<node CREATED="1704317059760" ID="ID_1022278502" MODIFIED="1704317061951" TEXT="Iteration">
+<node CREATED="1704317071234" ID="ID_731227047" MODIFIED="1704317076070" TEXT="Abbruch pr&#xfc;fen"/>
+<node CREATED="1704317076874" ID="ID_699422154" MODIFIED="1704317104362" TEXT="Intervall teilen: m"/>
+<node CREATED="1704317083038" ID="ID_1260760369" MODIFIED="1704317115617">
+<richcontent TYPE="NODE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      Mittelpunkt <b>auswerten</b>: test(m)
+    </p>
+  </body>
+</html>
+</richcontent>
+<node CREATED="1704317129562" ID="ID_160740709" MODIFIED="1704317166218" TEXT="true &#x27fc; [lower, m]"/>
+<node CREATED="1704317167008" ID="ID_227786504" MODIFIED="1704317178064" TEXT="false &#x27fc; [m, upper]"/>
+</node>
+</node>
+</node>
+<node CREATED="1704317215639" ID="ID_250813072" MODIFIED="1704317220333" TEXT="Einstiegs-Varianten">
+<node CREATED="1704317372561" ID="ID_902270424" MODIFIED="1704317376906" TEXT="lower pr&#xfc;fen">
+<node CREATED="1704317242076" ID="ID_540462019" MODIFIED="1704317358168" TEXT="true &#x27fc; Intervallverschiebung+Vergr&#xf6;&#xdf;erung &#x25bd;"/>
+<node CREATED="1704317389152" ID="ID_1595570689" MODIFIED="1704317398327" TEXT="sonst: upper pr&#xfc;fen"/>
+</node>
+<node CREATED="1704317230133" ID="ID_821454359" MODIFIED="1704317232648" TEXT="upper pr&#xfc;fen">
+<node CREATED="1704317242076" ID="ID_1523564757" MODIFIED="1704317363990" TEXT="false &#x27fc; Intervallverschiebung+Vergr&#xf6;&#xdf;erung &#x25b3;"/>
+<node CREATED="1704317412253" ID="ID_884069153" MODIFIED="1704317421832" TEXT="sonst Basis-Algo [lower, upper]"/>
+</node>
+</node>
+<node CREATED="1704317427155" ID="ID_366800456" MODIFIED="1704317431566" TEXT="Datensammlung">
+<node CREATED="1704317465350" ID="ID_1437456177" MODIFIED="1704317479448" TEXT="Ergebnistupel aller Auswertungen werden in einem Vector gesammelt"/>
+<node CREATED="1704317540235" ID="ID_696343908" MODIFIED="1704317608812" TEXT="man kann dann das letzte Ergebnis nehmen, oder mehrere mitteln"/>
+</node>
 </node>
 </node>
 </node>