Avoid compilation errors in the ResourceMonitor on non-Linux platforms

Author: victorreijgwart

library/cpp/include/wavemap/core/utils/profile/resource_monitor.h

@@ -144,10 +144,10 @@ class ResourceMonitor {
   bool running_ = false;
 
   /// @brief Stores the CPU time at the start of the current episode.
-  timespec episode_start_cpu_time_{};
+  std::timespec episode_start_cpu_time_{};
 
   /// @brief Stores the wall clock time at the start of the current episode.
-  timespec episode_start_wall_time_{};
+  std::timespec episode_start_wall_time_{};
 
   /// @brief Stores the CPU time duration of the last completed episode.
   Duration last_episode_cpu_duration_{};
@@ -168,7 +168,8 @@ class ResourceMonitor {
    * @param stop The ending POSIX timestamp.
    * @return The computed duration as a wavemap::Duration.
    */
-  static Duration computeDuration(const timespec& start, const timespec& stop);
+  static Duration computeDuration(const std::timespec& start,
+                                  const std::timespec& stop);
 };
 
 }  // namespace wavemap

library/cpp/src/core/utils/profile/resource_monitor.cc

@@ -2,7 +2,17 @@
 
 #include <fstream>
 #include <iomanip>
+#include <optional>
 #include <sstream>
+#include <string>
+
+// Borrowed from BOOST_HAS_CLOCK_GETTIME
+// NOTE: This is predicated on _POSIX_TIMERS (also on _XOPEN_REALTIME
+//       but at least one platform - linux - defines that flag without
+//       defining clock_gettime):
+#if (defined(_POSIX_TIMERS) && (_POSIX_TIMERS + 0 >= 0))
+#define HAS_CLOCK_GETTIME
+#endif
 
 namespace wavemap {
 void ResourceMonitor::start() {
@@ -11,8 +21,13 @@ void ResourceMonitor::start() {
     return;
   }
 
+#ifdef HAS_CLOCK_GETTIME
   clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &episode_start_cpu_time_);
   clock_gettime(CLOCK_MONOTONIC, &episode_start_wall_time_);
+#else
+  LOG(WARNING) << "Measuring CPU time has not yet been implemented for the "
+                  "current platform.";
+#endif
   running_ = true;
 }
 
@@ -22,10 +37,15 @@ void ResourceMonitor::stop() {
     return;
   }
 
-  timespec episode_stop_cpu_time{};
-  timespec episode_stop_wall_time{};
+  std::timespec episode_stop_cpu_time{};
+  std::timespec episode_stop_wall_time{};
+#ifdef HAS_CLOCK_GETTIME
   clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &episode_stop_cpu_time);
   clock_gettime(CLOCK_MONOTONIC, &episode_stop_wall_time);
+#else
+  LOG(WARNING) << "Measuring CPU time has not yet been implemented for the "
+                  "current platform.";
+#endif
   running_ = false;
 
   last_episode_cpu_duration_ =
@@ -95,8 +115,8 @@ std::string ResourceMonitor::getTotalResourceUsageStats() const {
   return oss.str();
 }
 
-Duration ResourceMonitor::computeDuration(const timespec& start,
-                                          const timespec& stop) {
+Duration ResourceMonitor::computeDuration(const std::timespec& start,
+                                          const std::timespec& stop) {
   return std::chrono::seconds(stop.tv_sec - start.tv_sec) +
          std::chrono::nanoseconds(stop.tv_nsec - start.tv_nsec);
 }