[metrics] Adjusted function names and documentation

lib/include/srslte/system/sys_metrics_processor.h

@@ -28,14 +28,13 @@
 
 namespace srslte {
 
-/// Process the data from the proc_stats_info.
+/// Process information from the system to create sys_metrics_t. The information is processed from the /proc/ system.
 class sys_metrics_processor
 {
-  /// Contains the information of a process.
+  /// Helper class used to parse the information from the /proc/[pid]/stats.
   struct proc_stats_info {
     proc_stats_info();
 
-    /// Parsed every field in /proc/[pid]/stats file.
     int           pid, ppid, pgrp, session, tty_nr, tpgid, exit_signal, processor, exit_code;
     unsigned      flags, rt_priority, policy;
     unsigned long minflt, cminflt, majflt, cmajflt, utime, stime, vsize, rsslim, startcode, endcode, startstack,
@@ -48,17 +47,18 @@ class sys_metrics_processor
   };
 
 public:
-  /// Performs a new measure and returns the values.
+  /// Measures and returns the system metrics.
   sys_metrics_t get_metrics();
 
 private:
-  /// Returns the cpu usage in %. current_query is the most recent proc_stats_info, and delta_time_in_seconds is the
-  /// elapsed time between the last measure and current in seconds.
-  /// NOTE: Returns -1.0f on error.
-  float cpu_usage(const proc_stats_info& current_query, float delta_time_in_seconds) const;
+  /// Calculates and returns the cpu usage in %. current_query is the most recent proc_stats_info, and
+  /// delta_time_in_seconds is the elapsed time between the last measure and current in seconds. NOTE: Returns -1.0f on
+  /// error.
+  float calculate_cpu_usage(const proc_stats_info& current_query, float delta_time_in_seconds) const;
 
-  /// Returns the memory usage in kB. First element is the real mem whereas the second is the virtual mem.
-  void mem_usage(sys_metrics_t& metrics) const;
+  /// Calculate the memory parameters and writes them in metrics.
+  /// NOTE: on error, metrics memory parameters are set to 0.
+  void calculate_mem_usage(sys_metrics_t& metrics) const;
 
 private:
   proc_stats_info                                    last_query;

lib/src/system/sys_metrics_processor.cpp

@@ -58,12 +58,12 @@ sys_metrics_t sys_metrics_processor::get_metrics()
   sys_metrics_t metrics;
 
   // Get the memory metrics.
-  mem_usage(metrics);
+  calculate_mem_usage(metrics);
 
   // Get the stats from the proc.
   proc_stats_info current_query;
   metrics.thread_count      = current_query.num_threads;
-  metrics.process_cpu_usage = cpu_usage(current_query, measure_interval_ms / 1000.f);
+  metrics.process_cpu_usage = calculate_cpu_usage(current_query, measure_interval_ms / 1000.f);
 
   // Update the last values.
   last_query_time = current_time;
@@ -72,7 +72,8 @@ sys_metrics_t sys_metrics_processor::get_metrics()
   return metrics;
 }
 
-float sys_metrics_processor::cpu_usage(const proc_stats_info& current_query, float delta_time_in_seconds) const
+float sys_metrics_processor::calculate_cpu_usage(const proc_stats_info& current_query,
+                                                 float                  delta_time_in_seconds) const
 {
   // Error current value has to be greater than last value.
   if (current_query.stime < last_query.stime || current_query.utime < last_query.utime) {
@@ -103,11 +104,26 @@ static unsigned read_memory_value_from_line(const std::string& line)
   return value;
 }
 
+/// Sets the memory parameters of the given metrics to zero.
+static void set_mem_to_zero(sys_metrics_t& metrics)
+{
+  metrics.process_realmem_kB    = 0;
+  metrics.process_virtualmem_kB = 0;
+  metrics.process_virtualmem    = 0;
+  metrics.process_realmem       = 0;
+  metrics.system_mem            = 0;
+}
+
 static void calculate_percentage_memory(sys_metrics_t& metrics)
 {
   std::ifstream file("/proc/meminfo");
   std::string   line;
 
+  if (!file) {
+    set_mem_to_zero(metrics);
+    return;
+  }
+
   // Total system's memory is in the first line.
   std::getline(file, line);
   unsigned long long total_mem_kB = read_memory_value_from_line(line);
@@ -123,11 +139,16 @@ static void calculate_percentage_memory(sys_metrics_t& metrics)
   metrics.system_mem         = (1.f - float(available_mem_kB) / float(total_mem_kB)) * 100.f;
 }
 
-void sys_metrics_processor::mem_usage(sys_metrics_t& metrics) const
+void sys_metrics_processor::calculate_mem_usage(sys_metrics_t& metrics) const
 {
   std::ifstream file("/proc/self/status");
   std::string   line;
 
+  if (!file) {
+    set_mem_to_zero(metrics);
+    return;
+  }
+
   while (std::getline(file, line)) {
     // Looks for Virtual memory.
     if (line.find("VmSize:") != std::string::npos) {