// Copyright 2017 The Abseil Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // // This file includes routines to find out characteristics // of the machine a program is running on. It is undoubtedly // system-dependent. // Functions listed here that accept a pid_t as an argument act on the // current process if the pid_t argument is 0 // All functions here are thread-hostile due to file caching unless // commented otherwise. #ifndef ABSL_BASE_INTERNAL_SYSINFO_H_ #define ABSL_BASE_INTERNAL_SYSINFO_H_ #ifndef _WIN32 #include <sys/types.h> #endif #include <cstdint> #include "absl/base/config.h" #include "absl/base/port.h" namespace absl { ABSL_NAMESPACE_BEGIN namespace base_internal { // Nominal core processor cycles per second of each processor. This is _not_ // necessarily the frequency of the CycleClock counter (see cycleclock.h) // Thread-safe. double NominalCPUFrequency(); // Number of logical processors (hyperthreads) in system. Thread-safe. int NumCPUs(); // Return the thread id of the current thread, as told by the system. // No two currently-live threads implemented by the OS shall have the same ID. // Thread ids of exited threads may be reused. Multiple user-level threads // may have the same thread ID if multiplexed on the same OS thread. // // On Linux, you may send a signal to the resulting ID with kill(). However, // it is recommended for portability that you use pthread_kill() instead. #ifdef _WIN32 // On Windows, process id and thread id are of the same type according to the // return types of GetProcessId() and GetThreadId() are both DWORD, an unsigned // 32-bit type. using pid_t = uint32_t; #endif pid_t GetTID(); // Like GetTID(), but caches the result in thread-local storage in order // to avoid unnecessary system calls. Note that there are some cases where // one must call through to GetTID directly, which is why this exists as a // separate function. For example, GetCachedTID() is not safe to call in // an asynchronous signal-handling context nor right after a call to fork(). pid_t GetCachedTID(); } // namespace base_internal ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_BASE_INTERNAL_SYSINFO_H_