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