1// Copyright 2017 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15// This file includes routines to find out characteristics
16// of the machine a program is running on. It is undoubtedly
17// system-dependent.
18
19// Functions listed here that accept a pid_t as an argument act on the
20// current process if the pid_t argument is 0
21// All functions here are thread-hostile due to file caching unless
22// commented otherwise.
23
24#ifndef ABSL_BASE_INTERNAL_SYSINFO_H_
25#define ABSL_BASE_INTERNAL_SYSINFO_H_
26
27#ifndef _WIN32
28#include <sys/types.h>
29#else
30#include <intsafe.h>
31#endif
32
33#include "absl/base/port.h"
34
35namespace absl {
36namespace base_internal {
37
38// Nominal core processor cycles per second of each processor. This is _not_
39// necessarily the frequency of the CycleClock counter (see cycleclock.h)
40// Thread-safe.
41double NominalCPUFrequency();
42
43// Number of logical processors (hyperthreads) in system. Thread-safe.
44int NumCPUs();
45
46// Return the thread id of the current thread, as told by the system.
47// No two currently-live threads implemented by the OS shall have the same ID.
48// Thread ids of exited threads may be reused. Multiple user-level threads
49// may have the same thread ID if multiplexed on the same OS thread.
50//
51// On Linux, you may send a signal to the resulting ID with kill(). However,
52// it is recommended for portability that you use pthread_kill() instead.
53#ifdef _WIN32
54// On Windows, process id and thread id are of the same type according to
55// the return types of GetProcessId() and GetThreadId() are both DWORD.
56using pid_t = DWORD;
57#endif
58pid_t GetTID();
59
60} // namespace base_internal
61} // namespace absl
62
63#endif // ABSL_BASE_INTERNAL_SYSINFO_H_
64