[Lldb-commits] [lldb] [LLDB][Data Formatters] Calculate average and total time for summary providers within lldb (PR #102708)

[Michael Buch via lldb-commits]

================
@@ -174,6 +177,86 @@ struct StatisticsOptions {
   std::optional<bool> m_include_transcript;
 };
 
+/// A class that represents statistics about a TypeSummaryProviders invocations
+class SummaryStatistics {
+public:
+  explicit SummaryStatistics(std::string name, std::string impl_type)
+      : m_total_time(), m_impl_type(impl_type), m_name(name),
+        m_summary_count(0) {}
+
+  std::string GetName() const { return m_name; };
+  double GetTotalTime() const { return m_total_time.get().count(); }
+
+  uint64_t GetSummaryCount() const {
+    return m_summary_count.load(std::memory_order_relaxed);
+  }
+
+  StatsDuration &GetDurationReference() { return m_total_time; };
+
+  std::string GetSummaryKindName() const { return m_impl_type; }
+
+  llvm::json::Value ToJSON() const;
+
+  void IncrementSummaryCount() {
+    m_summary_count.fetch_add(1, std::memory_order_relaxed);
+  }
+
+private:
+  lldb_private::StatsDuration m_total_time;
+  std::string m_impl_type;
+  std::string m_name;
+  std::atomic<uint64_t> m_summary_count;
+};
+
+/// A class that wraps a std::map of SummaryStatistics objects behind a mutex.
+class SummaryStatisticsCache {
+public:
+  /// Basic RAII class to increment the summary count when the call is complete.
+  /// In the future this can be extended to collect information about the
+  /// elapsed time for a single request.
+  class SummaryInvocation {
+  public:
+    SummaryInvocation(SummaryStatistics &summary, SummaryStatisticsCache &cache)
+        : m_provider_key(summary.GetName()), m_cache(cache),
+          m_elapsed_time(summary.GetDurationReference()) {}
+    ~SummaryInvocation() { m_cache.OnInvoked(m_provider_key); }
+
+    /// Delete the copy constructor and assignment operator to prevent
+    /// accidental double counting.
+    /// @{
+    SummaryInvocation(const SummaryInvocation &) = delete;
+    SummaryInvocation &operator=(const SummaryInvocation &) = delete;
+    /// @}
+
+  private:
+    std::string m_provider_key;
+    SummaryStatisticsCache &m_cache;
+    ElapsedTime m_elapsed_time;
+  };
+
+  /// Get the SummaryStatistics object for a given provider name, or insert
+  /// if statistics for that provider is not in the map.
+  SummaryStatisticsCache::SummaryInvocation
+  GetSummaryStatisticsForProviderName(lldb_private::TypeSummaryImpl &provider) {
+    std::lock_guard<std::mutex> guard(m_map_mutex);
+    auto pair = m_summary_stats_map.try_emplace(
+        provider.GetName(), provider.GetName(), provider.GetSummaryKindName());
+
+    return SummaryInvocation(pair.first->second, *this);
+  }
+
+  llvm::json::Value ToJSON();
+
+private:
+  /// Called when Summary Invocation is destructed.
+  void OnInvoked(std::string provider_name) noexcept {
+    // .at give us a const reference, and [provider_name] = will give us a copy
+    m_summary_stats_map.find(provider_name)->second.IncrementSummaryCount();
----------------
Michael137 wrote:

This needs to happen under a lock since `GetSummaryStatisticsForProviderName` mutates the map, while this reads from it. Also, I see you're not updating the elapsed time. Is that intentional?

Also, can we assert that `find` isn't `m_summary_stats_map.end()`?

https://github.com/llvm/llvm-project/pull/102708