Remove TimeLogManager and make TimeLogger singleton (#3494)

* Remove TimeLogManager and make TimeLogger monostate

* Static member initialization

* Switch from monostate to singleton

* Remove static member from monstate

* Add doc string

cpp/dolfinx/common/CMakeLists.txt

@@ -12,7 +12,6 @@ set(HEADERS_common
     ${CMAKE_CURRENT_SOURCE_DIR}/Table.h
     ${CMAKE_CURRENT_SOURCE_DIR}/Timer.h
     ${CMAKE_CURRENT_SOURCE_DIR}/TimeLogger.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/TimeLogManager.h
     ${CMAKE_CURRENT_SOURCE_DIR}/timing.h
     ${CMAKE_CURRENT_SOURCE_DIR}/utils.h
     PARENT_SCOPE
@@ -26,6 +25,5 @@ target_sources(
           ${CMAKE_CURRENT_SOURCE_DIR}/MPI.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/Table.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/TimeLogger.cpp
-          ${CMAKE_CURRENT_SOURCE_DIR}/TimeLogManager.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/timing.cpp
 )

cpp/dolfinx/common/TimeLogger.cpp

@@ -12,6 +12,13 @@
 using namespace dolfinx;
 using namespace dolfinx::common;
 
+//-----------------------------------------------------------------------------
+TimeLogger& TimeLogger::instance()
+{
+  static TimeLogger _instance{};
+  return _instance;
+}
+
 //-----------------------------------------------------------------------------
 void TimeLogger::register_timing(
     std::string task, std::chrono::duration<double, std::ratio<1>> time)

cpp/dolfinx/common/TimeLogger.h

@@ -16,21 +16,16 @@
 
 namespace dolfinx::common
 {
-/// Timer logging
+/// @brief Time logger maintaining data collected by Timer, if registered.
+///
+/// @note This is a monotstate, i.e. the data members are static and thus
+/// timings are aggregated into a single map.
 class TimeLogger
 {
 public:
-  /// Constructor
-  TimeLogger() = default;
-
-  // This class is used as a singleton and thus should not allow copies.
-  TimeLogger(const TimeLogger&) = delete;
-
-  // This class is used as a singleton and thus should not allow copies.
-  TimeLogger& operator=(const TimeLogger&) = delete;
-
-  /// Destructor
-  ~TimeLogger() = default;
+  /// @brief Singleton access.
+  /// @return Unique time logger object.
+  static TimeLogger& instance();
 
   /// Register timing (for later summary)
   void register_timing(std::string task,
@@ -58,6 +53,18 @@ class TimeLogger
   timings() const;
 
 private:
+  /// Constructor
+  TimeLogger() = default;
+
+  // This class is used as a singleton and thus should not allow copies.
+  TimeLogger(const TimeLogger&) = delete;
+
+  // This class is used as a singleton and thus should not allow copies.
+  TimeLogger& operator=(const TimeLogger&) = delete;
+
+  /// Destructor
+  ~TimeLogger() = default;
+
   // List of timings for tasks, map from string to (num_timings,
   // total_wall_time)
   std::map<std::string,

cpp/dolfinx/common/Timer.h

@@ -7,12 +7,13 @@
 
 #pragma once
 
-#include "TimeLogManager.h"
 #include <chrono>
 #include <optional>
 #include <stdexcept>
 #include <string>
 
+#include "TimeLogger.h"
+
 namespace dolfinx::common
 {
 /// @brief Timer for measuring and logging elapsed time durations.
@@ -56,7 +57,7 @@ class Timer
     if (_start_time.has_value() and _task.has_value())
     {
       _acc += T::now() - *_start_time;
-      TimeLogManager::logger().register_timing(*_task, _acc);
+      TimeLogger::instance().register_timing(*_task, _acc);
     }
   }
 
@@ -121,7 +122,7 @@ class Timer
 
     if (_task.has_value())
     {
-      TimeLogManager::logger().register_timing(*_task, _acc);
+      TimeLogger::instance().register_timing(*_task, _acc);
       _task = std::nullopt;
     }
   }

cpp/dolfinx/common/timing.cpp

@@ -6,31 +6,30 @@
 
 #include "timing.h"
 #include "Table.h"
-#include "TimeLogManager.h"
 #include "TimeLogger.h"
 #include "Timer.h"
 
 //-----------------------------------------------------------------------
 dolfinx::Table dolfinx::timing_table()
 {
-  return dolfinx::common::TimeLogManager::logger().timing_table();
+  return dolfinx::common::TimeLogger::instance().timing_table();
 }
 //-----------------------------------------------------------------------------
 void dolfinx::list_timings(MPI_Comm comm, Table::Reduction reduction)
 {
-  dolfinx::common::TimeLogManager::logger().list_timings(comm, reduction);
+  dolfinx::common::TimeLogger::instance().list_timings(comm, reduction);
 }
 //-----------------------------------------------------------------------------
 std::pair<int, std::chrono::duration<double, std::ratio<1>>>
 dolfinx::timing(std::string task)
 {
-  return dolfinx::common::TimeLogManager::logger().timing(task);
+  return dolfinx::common::TimeLogger::instance().timing(task);
 }
 //-----------------------------------------------------------------------------
 std::map<std::string,
          std::pair<int, std::chrono::duration<double, std::ratio<1>>>>
 dolfinx::timings()
 {
-  return dolfinx::common::TimeLogManager::logger().timings();
+  return dolfinx::common::TimeLogger::instance().timings();
 }
 //-----------------------------------------------------------------------------