adding file name rotation to stats output

src/Makefile.in

@@ -91,6 +91,7 @@ MERC_H += pkt_processing.h
 MERC_H += pcap_file_io.h
 MERC_H += pcap_reader.h
 MERC_H += rnd_pkt_drop.h
+MERC_H += rotator.h
 MERC_H += signal_handling.h
 
 MERC_OBJ = $(MERCC:%.cc=%.o) $(MERC:%.c=%.o)

src/control.h

@@ -9,6 +9,7 @@
 #include <unistd.h>
 #include <string>
 #include <atomic>
+#include "rotator.h"
 #include "libmerc/libmerc.h"
 
 class controller {
@@ -18,11 +19,12 @@ class controller {
  const char *stats_filename,
  size_t num_secs) :
  mc{merc_ctx},
- stats_file{stats_filename},
+ stats_file{stats_filename, ".json.gz"},
  num_secs_between_writes{num_secs},
  count{num_secs},
  controller_thread{},
- shutdown_requested{false}
+ shutdown_requested{false},
+ has_run_at_least_once{false}
  {
  if (mc == nullptr) {
  throw "error: null mercury context passed to control thread";
@@ -35,19 +37,22 @@ class controller {
  }
 
 private:
+
  mercury_context mc;
- std::string stats_file;
+ rotator stats_file;
  size_t num_secs_between_writes;
  size_t count;
  std::thread controller_thread;
  std::atomic<bool> shutdown_requested;
+ bool has_run_at_least_once;
 
  void run_tasks() {
  while (shutdown_requested.load() == false) {
  if (count == 0) {
  count = num_secs_between_writes;
- if (mercury_write_stats_data(mc, stats_file.c_str()) == false) {
- fprintf(stderr, "error: could not write stats file %s\n", stats_file.c_str());
+ const char *fname = stats_file.get_next_name();
+ if (mercury_write_stats_data(mc, fname) == false) {
+ fprintf(stderr, "error: could not write stats file %s\n", fname);
  }
  }
  --count;
@@ -64,6 +69,12 @@ class controller {
  if(controller_thread.joinable()) {
  controller_thread.join();
  }
+ if (!has_run_at_least_once) {
+ const char *fname = stats_file.get_current_name();
+ if (mercury_write_stats_data(mc, fname) == false) {
+ fprintf(stderr, "error: could not write stats file %s\n", fname);
+ }
+ }
  }
 
 };

src/mercury.c

@@ -541,7 +541,7 @@ int main(int argc, char *argv[]) {
 
  controller *ctl = nullptr;
  if (cfg.stats_filename) {
- ctl = new controller{mc, "mercury-stats.json.gz", 2};
+ ctl = new controller{mc, cfg.stats_filename, 30};
  }
 
  pthread_t output_thread;

src/rotator.h

@@ -0,0 +1,56 @@
+// rotator.h
+//
+// file name rotation
+
+#ifndef ROTATOR_H
+#define ROTATOR_H
+
+#include <string>
+
+class rotator {
+public:
+
+ rotator(const char *filename,
+ const char *filename_extension=nullptr) :
+ file_number{0},
+ base_name{filename},
+ extension{filename_extension},
+ file_name{filename}
+ {
+ file_name.append(extension);
+ }
+
+ const char *get_next_name() {
+ /*
+ * create filename that includes sequence number and date/timestamp
+ */
+ file_name = base_name;
+
+ char file_num[MAX_HEX];
+ snprintf(file_num, MAX_HEX, "%x", file_number++);
+ file_name.append("-").append(file_num);
+
+ char time_str[128];
+ struct timeval now;
+ gettimeofday(&now, NULL);
+ strftime(time_str, sizeof(time_str) - 1, "%Y-%m-%d-%H-%M-%S", localtime(&now.tv_sec));
+ file_name.append("-").append(time_str);
+
+ file_name.append(extension);
+
+ return file_name.c_str();
+ }
+
+ const char *get_current_name() const {
+ return file_name.c_str();
+ }
+
+private:
+ unsigned int file_number;
+ std::string base_name; // prefix common to all files
+ std::string extension; // extension, if any
+ std::string file_name; // name of current file
+
+};
+
+#endif // ROTATOR_H