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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/threading/platform_thread_internal_posix.h"
#include <errno.h>
#include <sys/resource.h>
#include <ostream>
#include "base/containers/adapters.h"
#include "base/logging.h"
#include "base/notimplemented.h"
namespace base::internal {
ThreadType NiceValueToThreadTypeForTest(int nice_value) {
// Try to find a priority that best describes |nice_value|. If there isn't
// an exact match, this method returns the closest priority whose nice value
// is higher (lower priority) than |nice_value|.
for (const auto& pair : kThreadTypeToNiceValueMapForTest) {
if (pair.nice_value >= nice_value) {
return pair.priority;
}
}
// Reaching here means |nice_value| is more than any of the defined
// priorities. The lowest priority is suitable in this case.
return ThreadType::kBackground;
}
int GetCurrentThreadNiceValue() {
return GetThreadNiceValue(PlatformThreadId{0});
}
int GetThreadNiceValue(PlatformThreadId id) {
// Need to clear errno before calling getpriority():
// http://man7.org/linux/man-pages/man2/getpriority.2.html
errno = 0;
int nice_value = getpriority(PRIO_PROCESS, static_cast<id_t>(id.raw()));
if (errno != 0) {
DVPLOG(1) << "Failed to get nice value of thread ("
<< PlatformThread::CurrentId() << ")";
return 0;
}
return nice_value;
}
bool SetThreadNiceFromType(PlatformThreadId thread_id, ThreadType thread_type) {
// setpriority(2) should change the whole thread group's (i.e. process)
// priority. However, as stated in the bugs section of
// http://man7.org/linux/man-pages/man2/getpriority.2.html: "under the current
// Linux/NPTL implementation of POSIX threads, the nice value is a per-thread
// attribute". Also, 0 is preferred to the current thread id since it is
// equivalent but makes sandboxing easier (https://crbug.com/399473).
pid_t syscall_tid =
thread_id == PlatformThread::CurrentId() ? 0 : thread_id.raw();
const int nice_setting = internal::ThreadTypeToNiceValue(thread_type);
if (setpriority(PRIO_PROCESS, static_cast<id_t>(syscall_tid), nice_setting)) {
DVPLOG(1) << "Failed to set nice value of thread " << thread_id << " to "
<< nice_setting;
return false;
}
return true;
}
} // namespace base::internal
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