text: // Copyright 2010, Shuo Chen.  All rights reserved.
  // http://code.google.com/p/muduo/
  //
  // Use of this source code is governed by a BSD-style license
  // that can be found in the License file.
  
  // Author: Shuo Chen (chenshuo at chenshuo dot com)
  //
  
  #include "process_info.h"
  #include "current_thread.h"
  #include "file_util.h"
  
  #include <algorithm>
  
  #include <assert.h>
  #include <dirent.h>
  #include <pwd.h>
  #include <stdio.h> // snprintf
  #include <stdlib.h>
  #include <unistd.h>
  #include <sys/resource.h>
  #include <sys/times.h>
  #include <string>
  
  namespace base {
  namespace detail {
  __thread int t_numOpenedFiles = 0;
  int fdDirFilter(const struct dirent *d) {
    if (::isdigit(d->d_name[0])) {
      ++t_numOpenedFiles;
    }
    return 0;
  }
  
  __thread std::vector<pid_t> *t_pids = NULL;
  int taskDirFilter(const struct dirent *d) {
    if (::isdigit(d->d_name[0])) {
      t_pids->push_back(atoi(d->d_name));
    }
    return 0;
  }
  
  int scanDir(const char *dirpath, int (*filter)(const struct dirent *)) {
    struct dirent **namelist = NULL;
    int result = ::scandir(dirpath, &namelist, filter, alphasort);
    assert(namelist == NULL);
    return result;
  }
  
  Timestamp g_startTime = Timestamp::now();
  // assume those won't change during the life time of a process.
  int g_clockTicks = static_cast<int>(::sysconf(_SC_CLK_TCK));
  int g_pageSize = static_cast<int>(::sysconf(_SC_PAGE_SIZE));
  }
  }
  
  using namespace base;
  using namespace base::detail;
  
  pid_t ProcessInfo::pid() { return ::getpid(); }
  
  std::string ProcessInfo::pidString() {
    char buf[32];
    snprintf(buf, sizeof buf, "%d", pid());
    return buf;
  }
  
  uid_t ProcessInfo::uid() { return ::getuid(); }
  
  std::string ProcessInfo::username() {
    struct passwd pwd;
    struct passwd *result = NULL;
    char buf[8192];
    const char *name = "unknownuser";
  
    getpwuid_r(uid(), &pwd, buf, sizeof buf, &result);
    if (result) {
      name = pwd.pw_name;
    }
    return name;
  }
  
  uid_t ProcessInfo::euid() { return ::geteuid(); }
  
  Timestamp ProcessInfo::startTime() { return g_startTime; }
  
  int ProcessInfo::clockTicksPerSecond() { return g_clockTicks; }
  
  int ProcessInfo::pageSize() { return g_pageSize; }
  
  bool ProcessInfo::isDebugBuild() {
  #ifdef NDEBUG
    return false;
  #else
    return true;
  #endif
  }
  
  std::string ProcessInfo::hostname() {
    // HOST_NAME_MAX 64
    // _POSIX_HOST_NAME_MAX 255
    char buf[256];
    if (::gethostname(buf, sizeof buf) == 0) {
      buf[sizeof(buf) - 1] = '\0';
      return buf;
    } else {
      return "unknownhost";
    }
  }
  
  std::string ProcessInfo::procname() { return procname(procStat()).as_string(); }
  
  StringPiece ProcessInfo::procname(const std::string &stat) {
    StringPiece name;
    size_t lp = stat.find('(');
    size_t rp = stat.rfind(')');
    if (lp != std::string::npos && rp != std::string::npos && lp < rp) {
      name.set(stat.data() + lp + 1, static_cast<int>(rp - lp - 1));
    }
    return name;
  }
  
  std::string ProcessInfo::procStatus() {
    std::string result;
    FileUtil::readFile("/proc/self/status", 65536, &result);
    return result;
  }
  
  std::string ProcessInfo::procStat() {
    std::string result;
    FileUtil::readFile("/proc/self/stat", 65536, &result);
    return result;
  }
  
  std::string ProcessInfo::threadStat() {
    char buf[64];
    snprintf(buf, sizeof buf, "/proc/self/task/%d/stat", CurrentThread::tid());
    std::string result;
    FileUtil::readFile(buf, 65536, &result);
    return result;
  }
  
  std::string ProcessInfo::exePath() {
    std::string result;
    char buf[1024];
    ssize_t n = ::readlink("/proc/self/exe", buf, sizeof buf);
    if (n > 0) {
      result.assign(buf, n);
    }
    return result;
  }
  
  int ProcessInfo::openedFiles() {
    t_numOpenedFiles = 0;
    scanDir("/proc/self/fd", fdDirFilter);
    return t_numOpenedFiles;
  }
  
  int ProcessInfo::maxOpenFiles() {
    struct rlimit rl;
    if (::getrlimit(RLIMIT_NOFILE, &rl)) {
      return openedFiles();
    } else {
      return static_cast<int>(rl.rlim_cur);
    }
  }
  
  ProcessInfo::CpuTime ProcessInfo::cpuTime() {
    ProcessInfo::CpuTime t;
    struct tms tms;
    if (::times(&tms) >= 0) {
      const double hz = static_cast<double>(clockTicksPerSecond());
      t.userSeconds = static_cast<double>(tms.tms_utime) / hz;
      t.systemSeconds = static_cast<double>(tms.tms_stime) / hz;
    }
    return t;
  }
  
  int ProcessInfo::numThreads() {
    int result = 0;
    std::string status = procStatus();
    size_t pos = status.find("Threads:");
    if (pos != std::string::npos) {
      result = ::atoi(status.c_str() + pos + 8);
    }
    return result;
  }
  
  std::vector<pid_t> ProcessInfo::threads() {
    std::vector<pid_t> result;
    t_pids = &result;
    scanDir("/proc/self/task", taskDirFilter);
    t_pids = NULL;
    std::sort(result.begin(), result.end());
    return result;
  }
  