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 "chrome/browser/extensions/api/system_cpu/cpu_info_provider.h"
6
7 #include <cstdio>
8 #include <sstream>
9
10 #include "base/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
QueryCpuTimePerProcessor(std::vector<linked_ptr<api::system_cpu::ProcessorInfo>> * infos)21 bool CpuInfoProvider::QueryCpuTimePerProcessor(
22 std::vector<linked_ptr<api::system_cpu::ProcessorInfo> >* infos) {
23 DCHECK(infos);
24
25 std::string contents;
26 if (!base::ReadFileToString(base::FilePath(kProcStat), &contents))
27 return false;
28
29 std::istringstream iss(contents);
30 std::string line;
31
32 // Skip the first line because it is just an aggregated number of
33 // all cpuN lines.
34 std::getline(iss, line);
35 size_t i = 0;
36 while (std::getline(iss, line)) {
37 if (line.compare(0, 3, "cpu") != 0)
38 continue;
39
40 // The number of entries in /proc/stat may mismatch the size of infos
41 // because the number of online processors may change after the value has
42 // been decided in CpuInfoProvider::QueryInfo().
43 //
44 // TODO(jchuang): fix the fail case by using the number of configured
45 // processors instead of online processors.
46 if (i == infos->size()) {
47 LOG(ERROR) << "Got more entries in /proc/stat than online CPUs";
48 return false;
49 }
50
51 uint64 user = 0, nice = 0, sys = 0, idle = 0;
52 int vals = sscanf(line.c_str(), "%*s %"PRIu64" %"PRIu64" %"PRIu64" %"PRIu64,
53 &user, &nice, &sys, &idle);
54 DCHECK_EQ(4, vals);
55
56 infos->at(i)->usage.kernel = static_cast<double>(sys);
57 infos->at(i)->usage.user = static_cast<double>(user + nice);
58 infos->at(i)->usage.idle = static_cast<double>(idle);
59 infos->at(i)->usage.total = static_cast<double>(sys + user + nice + idle);
60 ++i;
61 }
62 if (i < infos->size()) {
63 LOG(ERROR) << "Got fewer entries in /proc/stat than online CPUs";
64 return false;
65 }
66
67 return true;
68 }
69
70 } // namespace extensions
71