process-cpp  3.0.0
A simple convenience library for handling processes in C++11.
linux_process_test.cpp
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1 /*
2  * Copyright © 2013 Canonical Ltd.
3  *
4  * This program is free software: you can redistribute it and/or modify it
5  * under the terms of the GNU Lesser General Public License version 3,
6  * as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11  * GNU Lesser General Public License for more details.
12  *
13  * You should have received a copy of the GNU Lesser General Public License
14  * along with this program. If not, see <http://www.gnu.org/licenses/>.
15  *
16  * Authored by: Thomas Voß <thomas.voss@canonical.com>
17  */
18 
19 #include <core/posix/fork.h>
21 
26 
27 #include <gtest/gtest.h>
28 
29 #include <map>
30 
31 TEST(LinuxProcess, accessing_proc_stats_works)
32 {
33  auto child = core::posix::fork(
34  [](){ while(true); return core::posix::exit::Status::success;},
36 
38  EXPECT_NO_THROW(child >> stat);
40 }
41 
42 TEST(LinuxProcess, accessing_proc_oom_score_works)
43 {
45  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score);
46 }
47 
48 TEST(LinuxProcess, accessing_proc_oom_score_adj_works)
49 {
51  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score_adj);
52 }
53 
54 namespace
55 {
56 // A custom predicate to evaluate values in /proc/pid/oom_score.
57 // The file contains the oom_score as calculated by the kernel and we are racing
58 // against the badness heuristics. However, we only accept values within an error
59 // margin of 10 as the test process does not extensively allocate memory, uses hw devices etc..
60 ::testing::AssertionResult is_approximately_equal(int a, int b)
61 {
62  static const int error_margin = 10;
63 
64  if (::abs(a-b) <= 10)
65  return ::testing::AssertionSuccess() << ::abs(a-b) << " <= " << error_margin;
66 
67  return ::testing::AssertionFailure() << ::abs(a-b) << " > " << error_margin;
68 }
69 }
70 
71 TEST(LinuxProcess, adjusting_proc_oom_score_adj_works)
72 {
74  {
76  };
77  EXPECT_NO_THROW(core::posix::this_process::instance() << oom_score_adj);
78  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score_adj);
80  oom_score_adj.value);
82  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score);
83  EXPECT_TRUE(is_approximately_equal(oom_score.value, core::posix::linux::proc::process::OomScoreAdj::max_value()));
84 }
85 
86 // For this test we assume that we are not privileged and that the test binary
87 // does not have CAP_SYS_RESOURCE capabilities.
88 TEST(LinuxProcess, adjusting_proc_oom_score_adj_to_privileged_values_only_works_if_root)
89 {
91  {
93  };
94  EXPECT_NO_THROW(core::posix::this_process::instance() << oom_score_adj);
95  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score_adj);
96 
97  // If we are running on virtualized builders or buildds we are running under a fakeroot environment.
98  // However, that environment does not give us the required privileges and capabilities to adjust OOM values
99  // as we like. At any rate, this check seems to be flaky and we just comment it out.
100  // EXPECT_NE(core::posix::linux::proc::process::OomScoreAdj::min_value(),
101  // oom_score_adj.value);
102 }
103 
104 TEST(LinuxProcess, trying_to_write_an_invalid_oom_score_adj_throws)
105 {
107  {
109  };
110 
112 }
113 
114 TEST(LinuxProcess, adjusting_proc_oom_adj_works)
115 {
117  {
119  };
120  EXPECT_NO_THROW(core::posix::this_process::instance() << oom_adj);
121  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_adj);
123  oom_adj.value);
125  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_score);
126  // This looks weird as we are comparing to OomScoreAdj as opposed to OomAdj.
127  // However, /proc/pid/oom_adj is deprecated as of linux 2.6.36 and the value
128  // reported in oom_score is in the scale of /proc/pid/oom_score_adj, i.e., [-1000, 1000].
129  EXPECT_TRUE(is_approximately_equal(oom_score.value, core::posix::linux::proc::process::OomScoreAdj::max_value()));
130 }
131 
132 // For this test we assume that we are not privileged and that the test binary
133 // does not have CAP_SYS_RESOURCE capabilities.
134 TEST(LinuxProcess, adjusting_proc_oom_adj_to_privileged_values_does_not_work)
135 {
137  {
139  };
140  EXPECT_NO_THROW(core::posix::this_process::instance() << oom_adj);
141  EXPECT_NO_THROW(core::posix::this_process::instance() >> oom_adj);
142 
143  // If we are running on virtualized builders or buildds we are running under a fakeroot environment.
144  // However, that environment does not give us the required privileges and capabilities to adjust OOM values
145  // as we like. At any rate, this check seems to be flaky and we just comment it out.
146  // EXPECT_NE(core::posix::linux::proc::process::OomAdj::min_value(),
147  // oom_adj.value);
148 }
149 
150 TEST(LinuxProcess, trying_to_write_an_invalid_oom_adj_throws)
151 {
153  {
155  };
156 
158 }
static int max_value()
Returns the maximum valid value.
Definition: oom_adj.cpp:50
static int min_value()
Returns the minimum valid value.
The Stat struct encapsulates status information about a process.
Definition: stat.h:41
EXPECT_ANY_THROW(auto death_observer=core::posix::ChildProcess::DeathObserver::create_once_with_signal_trap(trap))
CORE_POSIX_DLL_PUBLIC ChildProcess fork(const std::function< posix::exit::Status()> &main, const StandardStream &flags)
fork forks a new process and executes the provided main function in the newly forked process...
Definition: fork.cpp:57
int value
Current OomScore as calculated by the kernel.
Definition: oom_score.h:52
static int min_value()
Returns the minimum valid value.
Definition: oom_adj.cpp:45
CORE_POSIX_DLL_PUBLIC Process instance() noexcept(true)
Returns a Process instance corresponding to this process.
static int max_value()
Returns the maximum valid value.
TEST(LinuxProcess, accessing_proc_stats_works)