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Common: Remove ThreadPool class

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No longer needed.
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Stenzek 2023-11-06 20:52:06 +10:00
parent 5b00ffb6cb
commit 6f66460ec0
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5 changed files with 0 additions and 375 deletions
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14
CMakeModules/aarch64-cross-toolchain.cmake
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@ -1,14 +0,0 @@
# Source: https://github.com/stenzek/duckstation/issues/626#issuecomment-660718306
# Target system
SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_PROCESSOR aarch64)
SET(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_CROSSCOMPILING TRUE)
# Cross compiler
SET(CMAKE_C_COMPILER aarch64-linux-gnu-gcc)
SET(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)
set(CMAKE_LIBRARY_ARCHITECTURE aarch64-linux-gnu)
set(THREADS_PTHREAD_ARG "0" CACHE STRING "Result from TRY_RUN" FORCE)

14
CMakeModules/armv7-cross-toolchain.cmake
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@ -1,14 +0,0 @@
# Source: https://github.com/stenzek/duckstation/issues/626#issuecomment-660718306
# Target system
SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_PROCESSOR armv7l)
SET(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_CROSSCOMPILING TRUE)
# Cross compiler
SET(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)
SET(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)
set(CMAKE_LIBRARY_ARCHITECTURE arm-linux-gnueabihf)
set(THREADS_PTHREAD_ARG "0" CACHE STRING "Result from TRY_RUN" FORCE)

2
src/common/CMakeLists.txt
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@ -49,8 +49,6 @@ add_library(common
small_string.h
string_util.cpp
string_util.h
thirdparty/thread_pool.cpp
thirdparty/thread_pool.h
threading.cpp
threading.h
timer.cpp

111
src/common/thirdparty/thread_pool.cpp vendored
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@ -1,111 +0,0 @@
// From https://raw.githubusercontent.com/cbraley/threadpool/master/src/thread_pool.cc
#include "thread_pool.h"
#include <cassert>
namespace cb {
// static
unsigned int ThreadPool::GetNumLogicalCores() {
// TODO(cbraley): Apparently this is broken in some older stdlib
// implementations?
const unsigned int dflt = std::thread::hardware_concurrency();
if (dflt == 0) {
// TODO(cbraley): Return some error code instead.
return 16;
} else {
return dflt;
}
}
ThreadPool::~ThreadPool() {
// TODO(cbraley): The current thread could help out to drain the work_ queue
// faster - for example, if there is work that hasn't yet been scheduled this
// thread could "pitch in" to help finish faster.
{
std::lock_guard<std::mutex> scoped_lock(mu_);
exit_ = true;
}
condvar_.notify_all(); // Tell *all* workers we are ready.
for (std::thread& thread : workers_) {
thread.join();
}
}
void ThreadPool::Wait() {
std::unique_lock<std::mutex> lock(mu_);
if (!work_.empty()) {
work_done_condvar_.wait(lock, [this] { return work_.empty(); });
}
}
ThreadPool::ThreadPool(int num_workers)
: num_workers_(num_workers), exit_(false) {
assert(num_workers_ > 0);
// TODO(cbraley): Handle thread construction exceptions.
workers_.reserve(num_workers_);
for (int i = 0; i < num_workers_; ++i) {
workers_.emplace_back(&ThreadPool::ThreadLoop, this);
}
}
void ThreadPool::Schedule(std::function<void(void)> func) {
ScheduleAndGetFuture(std::move(func)); // We ignore the returned std::future.
}
void ThreadPool::ThreadLoop() {
// Wait until the ThreadPool sends us work.
while (true) {
WorkItem work_item;
int prev_work_size = -1;
{
std::unique_lock<std::mutex> lock(mu_);
condvar_.wait(lock, [this] { return exit_ || (!work_.empty()); });
// ...after the wait(), we hold the lock.
// If all the work is done and exit_ is true, break out of the loop.
if (exit_ && work_.empty()) {
break;
}
// Pop the work off of the queue - we are careful to execute the
// work_item.func callback only after we have released the lock.
prev_work_size = work_.size();
work_item = std::move(work_.front());
work_.pop();
}
// We are careful to do the work without the lock held!
// TODO(cbraley): Handle exceptions properly.
work_item.func(); // Do work.
if (work_done_callback_) {
work_done_callback_(prev_work_size - 1);
}
// Notify a condvar is all work is done.
{
std::unique_lock<std::mutex> lock(mu_);
if (work_.empty() && prev_work_size == 1) {
work_done_condvar_.notify_all();
}
}
}
}
int ThreadPool::OutstandingWorkSize() const {
std::lock_guard<std::mutex> scoped_lock(mu_);
return work_.size();
}
int ThreadPool::NumWorkers() const { return num_workers_; }
void ThreadPool::SetWorkDoneCallback(std::function<void(int)> func) {
work_done_callback_ = std::move(func);
}
} // namespace cb

234
src/common/thirdparty/thread_pool.h vendored
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@ -1,234 +0,0 @@
// From https://raw.githubusercontent.com/cbraley/threadpool/master/src/thread_pool.h
#ifndef SRC_THREAD_POOL_H_
#define SRC_THREAD_POOL_H_
// A simple thread pool class.
// Usage examples:
//
// {
// ThreadPool pool(16); // 16 worker threads.
// for (int i = 0; i < 100; ++i) {
// pool.Schedule([i]() {
// DoSlowExpensiveOperation(i);
// });
// }
//
// // `pool` goes out of scope here - the code will block in the ~ThreadPool
// // destructor until all work is complete.
// }
//
// // TODO(cbraley): Add examples with std::future.
#include <condition_variable>
#include <functional>
#include <future>
#include <mutex>
#include <queue>
#include <thread>
#include <vector>
// We want to use std::invoke if C++17 is available, and fallback to "hand
// crafted" code if std::invoke isn't available.
#if __cplusplus >= 201703L
#define INVOKE_MACRO(CALLABLE, ARGS_TYPE, ARGS) std::invoke(CALLABLE, std::forward<ARGS_TYPE>(ARGS)...)
#elif __cplusplus >= 201103L
// Update this with http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4169.html.
#define INVOKE_MACRO(CALLABLE, ARGS_TYPE, ARGS) CALLABLE(std::forward<ARGS_TYPE>(ARGS)...)
#else
#error ("C++ version is too old! C++98 is not supported.")
#endif
namespace cb {
class ThreadPool {
public:
// Create a thread pool with `num_workers` dedicated worker threads.
explicit ThreadPool(int num_workers);
// Default construction is disallowed.
ThreadPool() = delete;
// Get the number of logical cores on the CPU. This is implemented using
// std::thread::hardware_concurrency().
// https://en.cppreference.com/w/cpp/thread/thread/hardware_concurrency
static unsigned int GetNumLogicalCores();
// The `ThreadPool` destructor blocks until all outstanding work is complete.
~ThreadPool();
// No copying, assigning, or std::move-ing.
ThreadPool& operator=(const ThreadPool&) = delete;
ThreadPool(const ThreadPool&) = delete;
ThreadPool(ThreadPool&&) = delete;
ThreadPool& operator=(ThreadPool&&) = delete;
// Add the function `func` to the thread pool. `func` will be executed at some
// point in the future on an arbitrary thread.
void Schedule(std::function<void(void)> func);
// Add `func` to the thread pool, and return a std::future that can be used to
// access the function's return value.
//
// *** Usage example ***
// Don't be alarmed by this function's tricky looking signature - this is
// very easy to use. Here's an example:
//
// int ComputeSum(std::vector<int>& values) {
// int sum = 0;
// for (const int& v : values) {
// sum += v;
// }
// return sum;
// }
//
// ThreadPool pool = ...;
// std::vector<int> numbers = ...;
//
// std::future<int> sum_future = ScheduleAndGetFuture(
// []() {
// return ComputeSum(numbers);
// });
//
// // Do other work...
//
// std::cout << "The sum is " << sum_future.get() << std::endl;
//
// *** Details ***
// Given a callable `func` that returns a value of type `RetT`, this
// function returns a std::future<RetT> that can be used to access
// `func`'s results.
template <typename FuncT, typename... ArgsT>
auto ScheduleAndGetFuture(FuncT&& func, ArgsT&&... args)
-> std::future<decltype(INVOKE_MACRO(func, ArgsT, args))>;
// Wait for all outstanding work to be completed.
void Wait();
// Return the number of outstanding functions to be executed.
int OutstandingWorkSize() const;
// Return the number of threads in the pool.
int NumWorkers() const;
void SetWorkDoneCallback(std::function<void(int)> func);
private:
void ThreadLoop();
// Number of worker threads - fixed at construction time.
int num_workers_;
// The destructor sets `exit_` to true and then notifies all workers. `exit_`
// causes each thread to break out of their work loop.
bool exit_;
mutable std::mutex mu_;
// Work queue. Guarded by `mu_`.
struct WorkItem {
std::function<void(void)> func;
};
std::queue<WorkItem> work_;
// Condition variable used to notify worker threads that new work is
// available.
std::condition_variable condvar_;
// Worker threads.
std::vector<std::thread> workers_;
// Condition variable used to notify that all work is complete - the work
// queue has "run dry".
std::condition_variable work_done_condvar_;
// Whenever a work item is complete, we call this callback. If this is empty,
// nothing is done.
std::function<void(int)> work_done_callback_;
};
namespace impl {
// This helper class simply returns a std::function that executes:
// ReturnT x = func();
// promise->set_value(x);
// However, this is tricky in the case where T == void. The code above won't
// compile if ReturnT == void, and neither will
// promise->set_value(func());
// To workaround this, we use a template specialization for the case where
// ReturnT is void. If the "regular void" proposal is accepted, this could be
// simpler:
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0146r1.html.
// The non-specialized `FuncWrapper` implementation handles callables that
// return a non-void value.
template <typename ReturnT>
struct FuncWrapper {
template <typename FuncT, typename... ArgsT>
std::function<void()> GetWrapped(
FuncT&& func, std::shared_ptr<std::promise<ReturnT>> promise,
ArgsT&&... args) {
// TODO(cbraley): Capturing by value is inefficient. It would be more
// efficient to move-capture everything, but we can't do this until C++14
// generalized lambda capture is available. Can we use std::bind instead to
// make this more efficient and still use C++11?
return [promise, func, args...]() mutable {
promise->set_value(INVOKE_MACRO(func, ArgsT, args));
};
}
};
template <typename FuncT, typename... ArgsT>
void InvokeVoidRet(FuncT&& func, std::shared_ptr<std::promise<void>> promise,
ArgsT&&... args) {
INVOKE_MACRO(func, ArgsT, args);
promise->set_value();
}
// This `FuncWrapper` specialization handles callables that return void.
template <>
struct FuncWrapper<void> {
template <typename FuncT, typename... ArgsT>
std::function<void()> GetWrapped(FuncT&& func,
std::shared_ptr<std::promise<void>> promise,
ArgsT&&... args) {
return [promise, func, args...]() mutable {
INVOKE_MACRO(func, ArgsT, args);
promise->set_value();
};
}
};
} // namespace impl
template <typename FuncT, typename... ArgsT>
auto ThreadPool::ScheduleAndGetFuture(FuncT&& func, ArgsT&&... args)
-> std::future<decltype(INVOKE_MACRO(func, ArgsT, args))> {
using ReturnT = decltype(INVOKE_MACRO(func, ArgsT, args));
// We are only allocating this std::promise in a shared_ptr because
// std::promise is non-copyable.
std::shared_ptr<std::promise<ReturnT>> promise =
std::make_shared<std::promise<ReturnT>>();
std::future<ReturnT> ret_future = promise->get_future();
impl::FuncWrapper<ReturnT> func_wrapper;
std::function<void()> wrapped_func = func_wrapper.GetWrapped(
std::move(func), std::move(promise), std::forward<ArgsT>(args)...);
// Acquire the lock, and then push the WorkItem onto the queue.
{
std::lock_guard<std::mutex> scoped_lock(mu_);
WorkItem work;
work.func = std::move(wrapped_func);
work_.emplace(std::move(work));
}
condvar_.notify_one(); // Tell one worker we are ready.
return ret_future;
}
} // namespace cb
#undef INVOKE_MACRO
#endif // SRC_THREAD_POOL_H_