extensions/browser/api/system_cpu/cpu_info_provider_linux.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "extensions/browser/api/system_cpu/cpu_info_provider.h"
   6
   7 #include <cstdio>
   8 #include <sstream>
   9
  10 #include "base/files/file_util.h"
  11 #include "base/format_macros.h"
  12
  13 namespace extensions {
  14
  15 namespace {
  16
  17 const char kProcStat[] = "/proc/stat";
  18
  19 }  // namespace
  20
  21 bool CpuInfoProvider::QueryCpuTimePerProcessor(
  22     std::vector<linked_ptr<api::system_cpu::ProcessorInfo>>* infos) {
  23   DCHECK(infos);
  24
  25   // WARNING: this method may return incomplete data because some processors may
  26   // be brought offline at runtime. /proc/stat does not report statistics of
  27   // offline processors. CPU usages of offline processors will be filled with
  28   // zeros.
  29   //
  30   // An example of output of /proc/stat when processor 0 and 3 are online, but
  31   // processor 1 and 2 are offline:
  32   //
  33   //   cpu  145292 20018 83444 1485410 995 44 3578 0 0 0
  34   //   cpu0 138060 19947 78350 1479514 570 44 3576 0 0 0
  35   //   cpu3 2033 32 1075 1400 52 0 1 0 0 0
  36   std::string contents;
  37   if (!base::ReadFileToString(base::FilePath(kProcStat), &contents))
  38     return false;
  39
  40   std::istringstream iss(contents);
  41   std::string line;
  42
  43   // Skip the first line because it is just an aggregated number of
  44   // all cpuN lines.
  45   std::getline(iss, line);
  46   while (std::getline(iss, line)) {
  47     if (line.compare(0, 3, "cpu") != 0)
  48       continue;
  49
  50     uint64 user = 0, nice = 0, sys = 0, idle = 0;
  51     uint32 pindex = 0;
  52     int vals =
  53         sscanf(line.c_str(),
  54                "cpu%" PRIu32 " %" PRIu64 " %" PRIu64 " %" PRIu64 " %" PRIu64,
  55                &pindex,
  56                &user,
  57                &nice,
  58                &sys,
  59                &idle);
  60     if (vals != 5 || pindex >= infos->size()) {
  61       NOTREACHED();
  62       return false;
  63     }
  64
  65     infos->at(pindex)->usage.kernel = static_cast<double>(sys);
  66     infos->at(pindex)->usage.user = static_cast<double>(user + nice);
  67     infos->at(pindex)->usage.idle = static_cast<double>(idle);
  68     infos->at(pindex)->usage.total =
  69         static_cast<double>(sys + user + nice + idle);
  70   }
  71
  72   return true;
  73 }
  74
  75 }  // namespace extensions