Add more information to the log timer dump

[aadsm]

Summary

The log timer dump is showing the time of the function itself minus any function that is called from this one that also happens to be timed. However, this is really not obvious and it also makes it hard to understand the time spent in total and also which children are actually taking the time.
To get a better reading of the timer dump I added the total, children (which I abbreviated to child) and also the hit count. I used these timers to figure out a performance issue and only after adding this things were more clear to me.

It looks like this:

(lldb) log timer dump
35.447713617 sec (total: 35.449s; child: 0.001s; count: 1374) for void SymbolFileDWARF::Index()
29.717921481 sec (total: 29.718s; child: 0.000s; count: 8230500) for const lldb_private::ConstString &lldb_private::Mangled::GetDemangledName(lldb::LanguageType) const
21.049508865 sec (total: 24.683s; child: 3.633s; count: 1399) for void lldb_private::Symtab::InitNameIndexes()
...

lldb/include/lldb/Utility/Timer.h

public:
   class Category {
   public:
     explicit Category(const char *category_name);
 
   private:
     friend class Timer;
     const char *m_name;
     std::atomic<uint64_t> m_nanos;
+    std::atomic<uint64_t> m_nanos_total;
+    std::atomic<uint64_t> m_nanos_child;
+    std::atomic<uint64_t> m_count;
     std::atomic<Category *> m_next;
 
     DISALLOW_COPY_AND_ASSIGN(Category);
   };
 
   /// Default constructor.
   Timer(Category &category, const char *format, ...)
       __attribute__((format(printf, 3, 4)));

lldb/source/Utility/Timer.cpp

 
 static TimerStack &GetTimerStackForCurrentThread() {
   static thread_local TimerStack g_stack;
   return g_stack;
 }
 
 Timer::Category::Category(const char *cat) : m_name(cat) {
   m_nanos.store(0, std::memory_order_release);
+  m_nanos_total.store(0, std::memory_order_release);
+  m_nanos_child.store(0, std::memory_order_release);
+  m_count.store(0, std::memory_order_release);
   Category *expected = g_categories;
   do {
     m_next = expected;
   } while (!g_categories.compare_exchange_weak(expected, this));
 }
 
 void Timer::SetQuiet(bool value) { g_quiet = value; }
 
Timer::~Timer() {
 
   assert(stack.back() == this);
   stack.pop_back();
   if (!stack.empty())
     stack.back()->ChildDuration(total_dur);
 
   // Keep total results for each category so we can dump results.
   m_category.m_nanos += std::chrono::nanoseconds(timer_dur).count();
+  m_category.m_nanos_total += std::chrono::nanoseconds(total_dur).count();
+  m_category.m_nanos_child +=
+      std::chrono::nanoseconds(m_child_duration).count();
+  m_category.m_count++;
 }
 
 void Timer::SetDisplayDepth(uint32_t depth) { g_display_depth = depth; }
 
 /* binary function predicate:
  * - returns whether a person is less than another person
  */
 
-typedef std::pair<const char *, uint64_t> TimerEntry;
+struct Stats {
+  uint64_t nanos;
+  uint64_t nanos_total;
+  uint64_t nanos_child;
+  uint64_t count;
+};
+typedef std::pair<const char *, Stats> TimerEntry;
 
 static bool CategoryMapIteratorSortCriterion(const TimerEntry &lhs,
                                              const TimerEntry &rhs) {
-  return lhs.second > rhs.second;
+  return lhs.second.nanos > rhs.second.nanos;
 }
 
 void Timer::ResetCategoryTimes() {
-  for (Category *i = g_categories; i; i = i->m_next)
+  for (Category *i = g_categories; i; i = i->m_next) {
     i->m_nanos.store(0, std::memory_order_release);
+    i->m_nanos_total.store(0, std::memory_order_release);
+    i->m_nanos_child.store(0, std::memory_order_release);
+    i->m_count.store(0, std::memory_order_release);
+  }
 }
 
 void Timer::DumpCategoryTimes(Stream *s) {
   std::vector<TimerEntry> sorted;
   for (Category *i = g_categories; i; i = i->m_next) {
     uint64_t nanos = i->m_nanos.load(std::memory_order_acquire);
+    uint64_t nanos_total = i->m_nanos_total.load(std::memory_order_acquire);
+    uint64_t nanos_child = i->m_nanos_child.load(std::memory_order_acquire);
+    uint64_t count = i->m_count.load(std::memory_order_acquire);
+    Stats stats{nanos, nanos_total, nanos_child, count};
     if (nanos)
-      sorted.push_back(std::make_pair(i->m_name, nanos));
+      sorted.push_back(std::make_pair(i->m_name, stats));
   }
   if (sorted.empty())
     return; // Later code will break without any elements.
 
   // Sort by time
   llvm::sort(sorted.begin(), sorted.end(), CategoryMapIteratorSortCriterion);
 
   for (const auto &timer : sorted)
-    s->Printf("%.9f sec for %s\n", timer.second / 1000000000., timer.first);
+    s->Printf("%.9f sec (total: %.3fs; child: %.3fs; count: %llu) for %s\n",
+              timer.second.nanos / 1000000000.,
+              timer.second.nanos_total / 1000000000.,
+              timer.second.nanos_child / 1000000000., timer.second.count,
+              timer.first);
 }

lldb/unittests/Utility/TimerTest.cpp

Timer::ResetCategoryTimes();
     std::this_thread::sleep_for(std::chrono::milliseconds(100));
     static Timer::Category tcat2("CAT2");
     Timer t2(tcat2, ".");
     std::this_thread::sleep_for(std::chrono::milliseconds(10));
   }
   StreamString ss;
   Timer::DumpCategoryTimes(&ss);
   double seconds1, seconds2;
-  ASSERT_EQ(2, sscanf(ss.GetData(), "%lf sec for CAT1%*[\n ]%lf sec for CAT2",
+  ASSERT_EQ(2, sscanf(ss.GetData(),
+                      "%lf sec (total: %*lfs; child: %*lfs; count: %*d) for "
+                      "CAT1%*[\n ]%lf sec for CAT2",
                       &seconds1, &seconds2))
       << "String: " << ss.GetData();
   EXPECT_LT(0.01, seconds1);
   EXPECT_GT(1, seconds1);
   EXPECT_LT(0.001, seconds2);
   EXPECT_GT(0.1, seconds2);
 }
+
+TEST(TimerTest, CategoryTimesStats) {
+  Timer::ResetCategoryTimes();
+  {
+    static Timer::Category tcat1("CAT1");
+    Timer t1(tcat1, ".");
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    static Timer::Category tcat2("CAT2");
+    Timer t2(tcat2, ".");
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+    Timer t3(tcat2, ".");
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+  }
+  // Example output:
+  // 0.102982273 sec (total: 0.126s; child: 0.023s; count: 1) for CAT1
+  // 0.023058228 sec (total: 0.036s; child: 0.012s; count: 2) for CAT2
+  StreamString ss;
+  Timer::DumpCategoryTimes(&ss);
+  double seconds1, total1, child1, seconds2;
+  int count1, count2;
+  ASSERT_EQ(
+      6, sscanf(ss.GetData(),
+                "%lf sec (total: %lfs; child: %lfs; count: %d) for CAT1%*[\n "
+                "]%lf sec (total: %*lfs; child: %*lfs; count: %d) for CAT2",
+                &seconds1, &total1, &child1, &count1, &seconds2, &count2))
+      << "String: " << ss.GetData();
+  EXPECT_GT(total1 - child1, seconds1 - 0.001);
+  EXPECT_LT(total1 - child1, seconds1 + 0.001);
+  EXPECT_EQ(1, count1);
+  EXPECT_GT(child1, seconds2 - 0.001);
+  EXPECT_LT(child1, seconds2 + 0.001);
+  EXPECT_EQ(2, count2);
+}