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#ifndef CAFFE2_UTILS_THREADPOOL_H_
#define CAFFE2_UTILS_THREADPOOL_H_
#include "ThreadPoolCommon.h"
#include <atomic>
#include <functional>
#include <memory>
#include <mutex>
#include <vector>
#include "caffe2/core/common.h"
//
// A work-stealing threadpool loosely based off of pthreadpool
//
namespace caffe2 {
struct Task;
class WorkersPool;
constexpr size_t kCacheLineSize = 64;
// A threadpool with the given number of threads.
// NOTE: the kCacheLineSize alignment is present only for cache
// performance, and is not strictly enforced (for example, when
// the object is created on the heap). Thus, in order to avoid
// misaligned intrinsics, no SSE instructions shall be involved in
// the ThreadPool implementation.
// Note: alignas is disabled because some compilers do not deal with
// CAFFE2_API and alignas annotations at the same time.
class CAFFE2_API /*alignas(kCacheLineSize)*/ ThreadPool {
public:
static std::unique_ptr<ThreadPool> defaultThreadPool();
ThreadPool(int numThreads);
~ThreadPool();
// Returns the number of threads currently in use
int getNumThreads() const;
void setNumThreads(size_t numThreads);
// Sets the minimum work size (range) for which to invoke the
// threadpool; work sizes smaller than this will just be run on the
// main (calling) thread
void setMinWorkSize(size_t size);
size_t getMinWorkSize() const {
return minWorkSize_;
}
void run(const std::function<void(int, size_t)>& fn, size_t range);
// Run an arbitrary function in a thread-safe manner accessing the Workers
// Pool
void withPool(const std::function<void(WorkersPool*)>& fn);
private:
static size_t defaultNumThreads_;
mutable std::mutex executionMutex_;
size_t minWorkSize_;
std::atomic_size_t numThreads_;
std::shared_ptr<WorkersPool> workersPool_;
std::vector<std::shared_ptr<Task>> tasks_;
};
} // namespace caffe2
#endif // CAFFE2_UTILS_THREADPOOL_H_
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