#722 Adding Host Name in Reporting (#733)

* Adding Host Name and test

* Addressing Review Comments

* Adding Test for JSON Reporter

* Adding HOST_NAME_MAX for MacOS systems

* Adding Explaination for MacOS HOST_NAME_MAX Addition

* Addressing Peer Review Comments

* Adding codecvt in windows header guard

* Changing name SystemInfo and adding empty message incase host name fetch fails

* Adding Comment on Struct SystemInfo

include/benchmark/benchmark.h

@@ -1293,6 +1293,15 @@ struct CPUInfo {
   BENCHMARK_DISALLOW_COPY_AND_ASSIGN(CPUInfo);
 };
 
+//Adding Struct for System Information
+struct SystemInfo {
+  std::string name;
+  static const SystemInfo& Get();
+ private:
+  SystemInfo();
+  BENCHMARK_DISALLOW_COPY_AND_ASSIGN(SystemInfo);
+};
+
 // Interface for custom benchmark result printers.
 // By default, benchmark reports are printed to stdout. However an application
 // can control the destination of the reports by calling
@@ -1302,6 +1311,7 @@ class BenchmarkReporter {
  public:
   struct Context {
     CPUInfo const& cpu_info;
+    SystemInfo const& sys_info;
     // The number of chars in the longest benchmark name.
     size_t name_field_width;
     static const char* executable_name;

src/json_reporter.cc

@@ -77,6 +77,8 @@ bool JSONReporter::ReportContext(const Context& context) {
   std::string walltime_value = LocalDateTimeString();
   out << indent << FormatKV("date", walltime_value) << ",\n";
 
+  out << indent << FormatKV("host_name", context.sys_info.name) << ",\n";
+
   if (Context::executable_name) {
     // windows uses backslash for its path separator,
     // which must be escaped in JSON otherwise it blows up conforming JSON

src/reporter.cc

@@ -79,7 +79,8 @@ void BenchmarkReporter::PrintBasicContext(std::ostream *out,
 // No initializer because it's already initialized to NULL.
 const char *BenchmarkReporter::Context::executable_name;
 
-BenchmarkReporter::Context::Context() : cpu_info(CPUInfo::Get()) {}
+BenchmarkReporter::Context::Context()
+    : cpu_info(CPUInfo::Get()), sys_info(SystemInfo::Get()) {}
 
 std::string BenchmarkReporter::Run::benchmark_name() const {
   std::string name = run_name;

src/sysinfo.cc

@@ -19,6 +19,7 @@
 #undef StrCat  // Don't let StrCat in string_util.h be renamed to lstrcatA
 #include <versionhelpers.h>
 #include <windows.h>
+#include <codecvt>
 #else
 #include <fcntl.h>
 #ifndef BENCHMARK_OS_FUCHSIA
@@ -52,6 +53,7 @@
 #include <limits>
 #include <memory>
 #include <sstream>
+#include <locale>
 
 #include "check.h"
 #include "cycleclock.h"
@@ -366,6 +368,35 @@ std::vector<CPUInfo::CacheInfo> GetCacheSizes() {
 #endif
 }
 
+std::string GetSystemName() {
+#if defined(BENCHMARK_OS_WINDOWS)
+  std::string str;
+  const unsigned COUNT = MAX_COMPUTERNAME_LENGTH+1;
+  TCHAR  hostname[COUNT] = {'\0'};
+  DWORD DWCOUNT = COUNT;
+  if (!GetComputerName(hostname, &DWCOUNT))
+    return std::string("");
+#ifndef UNICODE
+  str = std::string(hostname, DWCOUNT);
+#else
+  //Using wstring_convert, Is deprecated in C++17
+  using convert_type = std::codecvt_utf8<wchar_t>;
+  std::wstring_convert<convert_type, wchar_t> converter;
+  std::wstring wStr(hostname, DWCOUNT);
+  str = converter.to_bytes(wStr);
+#endif
+  return str;
+#else // defined(BENCHMARK_OS_WINDOWS)
+#ifdef BENCHMARK_OS_MACOSX //Mac Doesnt have HOST_NAME_MAX defined
+#define HOST_NAME_MAX 64
+#endif
+  char hostname[HOST_NAME_MAX];
+  int retVal = gethostname(hostname, HOST_NAME_MAX);
+  if (retVal != 0) return std::string("");
+  return std::string(hostname);
+#endif // Catch-all POSIX block.
+}
+
 int GetNumCPUs() {
 #ifdef BENCHMARK_HAS_SYSCTL
   int NumCPU = -1;
@@ -609,4 +640,11 @@ CPUInfo::CPUInfo()
       scaling_enabled(CpuScalingEnabled(num_cpus)),
       load_avg(GetLoadAvg()) {}
 
+
+const SystemInfo& SystemInfo::Get() {
+  static const SystemInfo* info = new SystemInfo();
+  return *info;
+}
+
+SystemInfo::SystemInfo() : name(GetSystemName()) {}
 }  // end namespace benchmark

test/reporter_output_test.cc

@@ -23,6 +23,7 @@ static int AddContextCases() {
            {{"^\\{", MR_Default},
             {"\"context\":", MR_Next},
             {"\"date\": \"", MR_Next},
+            {"\"host_name\":", MR_Next},
             {"\"executable\": \".*(/|\\\\)reporter_output_test(\\.exe)?\",",
              MR_Next},
             {"\"num_cpus\": %int,$", MR_Next},