Make logging output file name configurable (#233)

* Make log file name configurable

README.md

@@ -109,14 +109,16 @@ The `prmon` binary is invoked with the following arguments:
 
 ```sh
 prmon [--pid PPP] [--filename prmon.txt] [--json-summary prmon.json] \
-      [--interval 30] [--suppress-hw-info] [--units] [--netdev DEV] \
+      [--log-filename prmon.log] [--interval 30] \
+      [--suppress-hw-info] [--units] [--netdev DEV] \
       [--disable MON1] [--level LEV] [--level MON:LEV]\
       [-- prog arg arg ...]
 ```
 
 * `--pid` the 'mother' PID to monitor (all children in the same process tree are monitored as well)
 * `--filename` output file for time-stamped monitored values
 * `--json-summmary` output file for summary data written in JSON format
+* `--log-filename` output file for log messages
 * `--interval` time, in seconds, between monitoring snapshots
 * `--suppress-hw-info` flag that turns-off hardware information collection
 * `--units` add information on units for each metric to JSON file
@@ -165,6 +167,9 @@ with the current summary values. Use the `--units` option to see exactly
 which units are used for each metric (the value of `1` for a unit means
 it is a pure number).
 
+In the `log-filename` output file, log messages (e.g., errors, warnings etc.)
+are written.
+
 Monitoring of CPU, I/O and memory is reliably accurate, at least to within
 the sampling time. Monitoring of network I/O is **not reliable** unless the
 monitored process is isolated from other processes performing network I/O

package/src/MessageBase.h

@@ -9,10 +9,8 @@
 
 // Global sinks
 
-static const std::shared_ptr<spdlog::sinks::stdout_color_sink_st> c_sink{
-    std::make_shared<spdlog::sinks::stdout_color_sink_st>()};
-static const std::shared_ptr<spdlog::sinks::basic_file_sink_st> f_sink{
-    std::make_shared<spdlog::sinks::basic_file_sink_st>("prmon.log", true)};
+extern std::shared_ptr<spdlog::sinks::stdout_color_sink_st> c_sink;
+extern std::shared_ptr<spdlog::sinks::basic_file_sink_st> f_sink;
 
 // Map from monitor to logging level
 

package/src/prmon.cpp

@@ -31,6 +31,9 @@
 #include "utils.h"
 #include "wallmon.h"
 
+std::shared_ptr<spdlog::sinks::stdout_color_sink_st> c_sink;
+std::shared_ptr<spdlog::sinks::basic_file_sink_st> f_sink;
+
 bool prmon::sigusr1 = false;
 
 int ProcessMonitor(const pid_t mpid, const std::string filename,
@@ -229,22 +232,16 @@ int main(int argc, char* argv[]) {
   // Set defaults
   const char* default_filename = "prmon.txt";
   const char* default_json_summary = "prmon.json";
+  const char* default_log_filename = "prmon.log";
   const unsigned int default_interval = 30;
   const bool default_store_hw_info = true;
   const bool default_store_unit_info = false;
 
-  // Set up global default logger
-  spdlog::sinks_init_list s_list = {c_sink, f_sink};
-  auto logger =
-      std::make_shared<spdlog::logger>("prmon", s_list.begin(), s_list.end());
-  logger->set_level(spdlog::level::warn);
-  logger->flush_on(spdlog::level::warn);
-  spdlog::set_default_logger(logger);
-
   pid_t pid = -1;
   bool got_pid = false;
   std::string filename{default_filename};
   std::string jsonSummary{default_json_summary};
+  std::string logFileName{default_log_filename};
   std::vector<std::string> netdevs{};
   std::vector<std::string> disabled_monitors{};
   unsigned int interval{default_interval};
@@ -256,6 +253,7 @@ int main(int argc, char* argv[]) {
       {"pid", required_argument, NULL, 'p'},
       {"filename", required_argument, NULL, 'f'},
       {"json-summary", required_argument, NULL, 'j'},
+      {"log-filename", required_argument, NULL, 'o'},
       {"interval", required_argument, NULL, 'i'},
       {"disable", required_argument, NULL, 'd'},
       {"suppress-hw-info", no_argument, NULL, 's'},
@@ -266,7 +264,7 @@ int main(int argc, char* argv[]) {
       {0, 0, 0, 0}};
 
   int c;
-  while ((c = getopt_long(argc, argv, "-p:f:j:i:d:sun:h:l:", long_options,
+  while ((c = getopt_long(argc, argv, "-p:f:j:o:i:d:sun:h:l:", long_options,
                           NULL)) != -1) {
     switch (char(c)) {
       case 'p':
@@ -279,6 +277,9 @@ int main(int argc, char* argv[]) {
       case 'j':
         jsonSummary = optarg;
         break;
+      case 'o':
+        logFileName = optarg;
+        break;
       case 'i':
         interval = std::stoi(optarg);
         break;
@@ -303,7 +304,7 @@ int main(int argc, char* argv[]) {
         processLevel(std::string(optarg));
         break;
       default:
-        spdlog::error("Use '--help' for usage ");
+        std::cerr << "Use '--help' for usage " << std::endl;
         return 1;
     }
   }
@@ -325,6 +326,8 @@ int main(int argc, char* argv[]) {
         << default_filename << ")\n"
         << "[--json-summary, -j FILE] Filename for JSON summary (default "
         << default_json_summary << ")\n"
+        << "[--log-filename, -o FILE] Filename for logging (default "
+        << default_log_filename << ")\n"
         << "[--interval, -i TIME]     Seconds between samples (default "
         << default_interval << ")\n"
         << "[--suppress-hw-info, -s]  Disable hardware information (default "
@@ -382,8 +385,13 @@ int main(int argc, char* argv[]) {
     return EXIT_FAILURE;
   }
 
-  // Now that we know given level option is valid, update the level of the
-  // global logger
+  // Set up the global logger
+  c_sink = std::make_shared<spdlog::sinks::stdout_color_sink_st>();
+  f_sink =
+      std::make_shared<spdlog::sinks::basic_file_sink_st>(logFileName, true);
+  spdlog::sinks_init_list s_list = {c_sink, f_sink};
+  auto logger =
+      std::make_shared<spdlog::logger>("prmon", s_list.begin(), s_list.end());
   logger->set_level(global_logging_level);
   logger->flush_on(global_logging_level);
   spdlog::set_default_logger(logger);

package/tests/test_fields.cpp

@@ -29,6 +29,11 @@
 const std::string base_path = TO_STRING(PRMON_SOURCE_DIR);
 const std::string prmon_path = base_path + "/package/prmon";
 
+std::shared_ptr<spdlog::sinks::stdout_color_sink_st> c_sink{
+    std::make_shared<spdlog::sinks::stdout_color_sink_st>()};
+std::shared_ptr<spdlog::sinks::basic_file_sink_st> f_sink{
+    std::make_shared<spdlog::sinks::basic_file_sink_st>("prmon.log", true)};
+
 bool prmon::sigusr1 = false;
 
 int run_prmon(const std::vector<std::string>& disabled_monitors) {

package/tests/test_values.cpp

@@ -21,6 +21,11 @@ const std::vector<pid_t> mother_pid{1729};
 
 const std::string base_path = TO_STRING(TESTS_SOURCE_DIR);
 
+std::shared_ptr<spdlog::sinks::stdout_color_sink_st> c_sink{
+    std::make_shared<spdlog::sinks::stdout_color_sink_st>()};
+std::shared_ptr<spdlog::sinks::basic_file_sink_st> f_sink{
+    std::make_shared<spdlog::sinks::basic_file_sink_st>("prmon.log", true)};
+
 bool prmon::sigusr1 = false;
 
 TEST(IomonTest, IomonMonitonicityTestFixed) {