mirror of
https://github.com/slsdetectorgroup/slsDetectorPackage.git
synced 2026-06-27 21:29:20 +02:00
Erik Fröjdh
100 lines
3.0 KiB
C++
100 lines
3.0 KiB
C++
// SPDX-License-Identifier: LGPL-3.0-or-other
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// Copyright (C) 2021 Contributors to the SLS Detector Package
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#pragma once
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/**
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* @file thread_utils.h
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* @short Portable per-thread identifier for diagnostics/logging.
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*
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* Returns a unique-within-process thread id of the calling thread:
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* - Linux, glibc >= 2.30: the system gettid() (pid_t).
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* - Linux, glibc < 2.30: syscall(SYS_gettid) (long, cast to pid_t).
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* - macOS: pthread_threadid_np() (uint64_t, truncated to pid_t).
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*
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* The macOS kernel thread id is 64-bit. To stay drop-in compatible with the
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* existing call sites that store the result in pid_t (e.g. ThreadObject::
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* threadId, ClientInterface::parentThreadId / tcpThreadId), we truncate to
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* pid_t. The value is used for diagnostics only and is still unique enough
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* within a single process.
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*/
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#include <condition_variable>
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#include <mutex>
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#include <sys/types.h> // pid_t
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#if defined(__APPLE__)
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#include <cstdint>
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#include <pthread.h>
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#elif defined(__linux__)
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#include <unistd.h>
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#if !defined(__GLIBC__) || \
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!(__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 30))
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#include <sys/syscall.h>
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#endif
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#endif
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namespace sls {
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inline pid_t getThreadId() noexcept {
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#if defined(__APPLE__)
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std::uint64_t tid = 0;
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pthread_threadid_np(nullptr, &tid);
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return static_cast<pid_t>(tid);
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#elif defined(__GLIBC__) && \
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(__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 30))
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return ::gettid();
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#else
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return static_cast<pid_t>(::syscall(SYS_gettid));
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#endif
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}
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/**
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* Minimal C++17 backport of the subset of std::counting_semaphore /
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* std::binary_semaphore used in this project. API matches the C++20 std types
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* (acquire / try_acquire / release with optional update count) so call sites
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* can switch to <semaphore> verbatim once the project moves to C++20. Built
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* on std::mutex + std::condition_variable; therefore NOT async-signal-safe,
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* do not call release() from a signal handler.
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*/
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class counting_semaphore {
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public:
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explicit counting_semaphore(int desired) : count_(desired) {}
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counting_semaphore(const counting_semaphore &) = delete;
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counting_semaphore &operator=(const counting_semaphore &) = delete;
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void acquire() {
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std::unique_lock<std::mutex> lk(mtx_);
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cv_.wait(lk, [this] { return count_ > 0; });
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--count_;
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}
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bool try_acquire() noexcept {
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std::lock_guard<std::mutex> lk(mtx_);
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if (count_ == 0)
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return false;
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--count_;
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return true;
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}
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void release(int update = 1) {
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{
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std::lock_guard<std::mutex> lk(mtx_);
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count_ += update;
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}
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if (update == 1)
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cv_.notify_one();
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else
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cv_.notify_all();
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}
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private:
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std::mutex mtx_;
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std::condition_variable cv_;
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int count_;
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};
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using binary_semaphore = counting_semaphore;
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} // namespace sls
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