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

[Jacob Lalonde via lldb-commits]

================
@@ -174,6 +176,83 @@ struct StatisticsOptions {
   std::optional<bool> m_include_transcript;
 };
 
+/// A class that represents statistics about a TypeSummaryProviders invocations
+class SummaryStatistics {
+public:
+  SummaryStatistics() = default;
+  SummaryStatistics(lldb_private::ConstString name) : 
+    m_total_time(), m_name(name), m_summary_count(0) {}
+
+  SummaryStatistics(const SummaryStatistics &&rhs)
+      : m_total_time(), m_name(rhs.m_name), m_summary_count(rhs.m_summary_count.load(std::memory_order_relaxed)) {}
+
+  lldb_private::ConstString GetName() const { return m_name; };
+  double GetAverageTime() const {
+    return m_total_time.get().count() / m_summary_count.load(std::memory_order_relaxed);
+  }
+
+  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;
+  }
+
+  llvm::json::Value ToJSON() const;
+
+  // 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) : m_summary(summary) {}
+    ~SummaryInvocation() {
+      m_summary.OnInvoked();
+    }
+  private:
+    SummaryStatistics &m_summary;
+  };
+
+private:
+  /// Called when Summary Invocation is destructed.
+  void OnInvoked() {
+    m_summary_count.fetch_add(1, std::memory_order_relaxed);
+  }
+
+  lldb_private::StatsDuration m_total_time;
+  lldb_private::ConstString 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:
+  SummaryStatisticsCache() = default;
+  /// Get the SummaryStatistics object for a given provider name, or insert
+  /// if statistics for that provider is not in the map.
+  lldb_private::SummaryStatistics &GetSummaryStatisticsForProviderName(lldb_private::ConstString summary_provider_name) {
+    m_map_mutex.lock();
+    if (m_summary_stats_map.count(summary_provider_name) == 0) {
+      m_summary_stats_map.emplace(summary_provider_name, SummaryStatistics(summary_provider_name));
+    }
+
+    SummaryStatistics &summary_stats = m_summary_stats_map.at(summary_provider_name);
+    m_map_mutex.unlock();
+    return summary_stats;
+  }
+
+  llvm::json::Value ToJSON();
+
+private:
+  std::map<lldb_private::ConstString, lldb_private::SummaryStatistics> m_summary_stats_map;
----------------
Jlalond wrote:

I originally picked `map` instead of `unordered_map` because I thought the user may want to know the order in which their summary providers were called, but it's only for the first time, so I'm not sure that's worth the lookup time cost

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