Bug fix for superslab meta-data (#302)

* Replace time measuring macro

The DO_TIME macro was used originally to get performance numbers. The
macro makes tests hard to debug. This commit replaces it with a proper
C++ class with destructor.

* Bug fix

If the superslab meta data is large, then the calculation for the
sizeclasses that could use the short slab was incorrect.  This fixes
that calculation.

Co-authored-by: Nathaniel Wesley Filardo <nfilardo@microsoft.com>

src/test/measuretime.h

@@ -3,12 +3,19 @@
 #include <chrono>
 #include <iomanip>
 #include <iostream>
+#include <sstream>
 
-#define DO_TIME(name, code) \
-  { \
-    auto start__ = std::chrono::high_resolution_clock::now(); \
-    code auto finish__ = std::chrono::high_resolution_clock::now(); \
-    auto diff__ = finish__ - start__; \
-    std::cout << name << ": " << std::setw(12) << diff__.count() << " ns" \
-              << std::endl; \
+class MeasureTime : public std::stringstream
+{
+  std::chrono::time_point<std::chrono::high_resolution_clock> start =
+    std::chrono::high_resolution_clock::now();
+
+public:
+  ~MeasureTime()
+  {
+    auto finish = std::chrono::high_resolution_clock::now();
+    auto diff = finish - start;
+    std::cout << str() << ": " << std::setw(12) << diff.count() << " ns"
+              << std::endl;
   }
+};

src/test/perf/contention/contention.cc

@@ -1,4 +1,3 @@
-#include "test/measuretime.h"
 #include "test/opt.h"
 #include "test/setup.h"
 #include "test/usage.h"

src/test/perf/external_pointer/externalpointer.cc

@@ -64,7 +64,9 @@ namespace test
 #endif
     setup(r, alloc);
 
-    DO_TIME("External pointer queries ", {
+    {
+      MeasureTime m;
+      m << "External pointer queries ";
       for (size_t i = 0; i < iterations; i++)
       {
         size_t rand = (size_t)r.next();
@@ -77,7 +79,7 @@ namespace test
         if (calced_external != external_ptr)
           abort();
       }
-    });
+    }
 
     teardown(alloc);
   }

src/test/perf/low_memory/low-memory.cc

@@ -1,6 +1,5 @@
 #include <iostream>
 #include <snmalloc.h>
-#include <test/measuretime.h>
 #include <test/opt.h>
 #include <test/setup.h>
 #include <unordered_set>

src/test/perf/singlethread/singlethread.cc

@@ -10,54 +10,55 @@ void test_alloc_dealloc(size_t count, size_t size, bool write)
 {
   auto* alloc = ThreadAlloc::get();
 
-  DO_TIME(
-    "Count: " << std::setw(6) << count << ", Size: " << std::setw(6) << size
-              << ", ZeroMem: " << (zero_mem == YesZero) << ", Write: " << write,
+  {
+    MeasureTime m;
+    m << "Count: " << std::setw(6) << count << ", Size: " << std::setw(6)
+      << size << ", ZeroMem: " << (zero_mem == YesZero) << ", Write: " << write;
+
+    std::unordered_set<void*> set;
+
+    // alloc 1.5x objects
+    for (size_t i = 0; i < ((count * 3) / 2); i++)
     {
-      std::unordered_set<void*> set;
+      void* p = alloc->alloc<zero_mem>(size);
+      SNMALLOC_CHECK(set.find(p) == set.end());
 
-      // alloc 1.5x objects
-      for (size_t i = 0; i < ((count * 3) / 2); i++)
-      {
-        void* p = alloc->alloc<zero_mem>(size);
-        SNMALLOC_CHECK(set.find(p) == set.end());
+      if (write)
+        *(int*)p = 4;
 
-        if (write)
-          *(int*)p = 4;
+      set.insert(p);
+    }
 
-        set.insert(p);
-      }
+    // free 0.25x of the objects
+    for (size_t i = 0; i < (count / 4); i++)
+    {
+      auto it = set.begin();
+      void* p = *it;
+      alloc->dealloc(p, size);
+      set.erase(it);
+      SNMALLOC_CHECK(set.find(p) == set.end());
+    }
 
-      // free 0.25x of the objects
-      for (size_t i = 0; i < (count / 4); i++)
-      {
-        auto it = set.begin();
-        void* p = *it;
-        alloc->dealloc(p, size);
-        set.erase(it);
-        SNMALLOC_CHECK(set.find(p) == set.end());
-      }
+    // alloc 1x objects
+    for (size_t i = 0; i < count; i++)
+    {
+      void* p = alloc->alloc<zero_mem>(size);
+      SNMALLOC_CHECK(set.find(p) == set.end());
 
-      // alloc 1x objects
-      for (size_t i = 0; i < count; i++)
-      {
-        void* p = alloc->alloc<zero_mem>(size);
-        SNMALLOC_CHECK(set.find(p) == set.end());
+      if (write)
+        *(int*)p = 4;
 
-        if (write)
-          *(int*)p = 4;
+      set.insert(p);
+    }
 
-        set.insert(p);
-      }
-
-      // free everything
-      while (!set.empty())
-      {
-        auto it = set.begin();
-        alloc->dealloc(*it, size);
-        set.erase(it);
-      }
-    });
+    // free everything
+    while (!set.empty())
+    {
+      auto it = set.begin();
+      alloc->dealloc(*it, size);
+      set.erase(it);
+    }
+  }
 
   current_alloc_pool()->debug_check_empty();
 }