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// ==========================================================================
// SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2018, Knut Reinert, FU Berlin
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of Knut Reinert or the FU Berlin nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL KNUT REINERT OR THE FU BERLIN BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
//
// ==========================================================================
// Author: Rene Rahn <rene.rahn@fu-berlin.de>
// ==========================================================================
#ifndef INCLUDE_SEQAN_PARALLEL_PARALLEL_THREAD_POOL_H_
#define INCLUDE_SEQAN_PARALLEL_PARALLEL_THREAD_POOL_H_
#if defined(__linux__)
#include <sched.h>
#endif // defined(__linux__)
namespace seqan
{
// ============================================================================
// Forwards
// ============================================================================
// ============================================================================
// Tags, Classes, Enums
// ============================================================================
/*!
* @class ThreadPool
* @headerfile <seqan/parallel.h>
* @brief Handles a pool of concurrent <a href="http://en.cppreference.com/w/cpp/thread/thread">std::threads</a>.
* @signature class ThreadPool;
*
* This is a simple raii-wrapper class to manage a set of <tt>std::threads</tt>.
*/
class ThreadPool
{
public:
//-------------------------------------------------------------------------
// Constructor.
/*!
* @fn ThreadPool::ThreadPool
* @brief The constructor.
* @signature ThreadPool::TThreadPool() = default;
* @signature ThreadPool::TThreadPool(ThreadPool const &) = delete;
* @signature ThreadPool::TThreadPool(ThreadPool &&) = delete;
*
* Creates a new instance with an empty pool.
*/
ThreadPool() = default;
ThreadPool(ThreadPool const &) = delete;
ThreadPool(ThreadPool &&) = delete;
ThreadPool& operator=(ThreadPool const &) = delete;
ThreadPool& operator=(ThreadPool &&) = delete;
/*!
* @fn ThreadPool::~ThreadPool
* @brief The destructor.
* @signature ThreadPool::~ThreadPool()
*
* Safely destroys the thread pool instance by joining all registered threads.
* This is an implicit barrier for the owning thread.
*
* @warning If threads cannot be joined (e.g. dead lock) the destructor will wait forever.
*/
~ThreadPool()
{
for_each(std::begin(_mPool), std::end(_mPool),
[] (auto & t)
{
if (t.joinable())
t.join();
});
}
//-------------------------------------------------------------------------
// Private Member Variables.
std::deque<std::thread> _mPool;
};
// ============================================================================
// Metafunctions
// ============================================================================
// ============================================================================
// Functions
// ============================================================================
/*!
* @fn ThreadPool#spawn
* @brief Spawns a new thread and registers it in the thread pool.
* @headerfile <seqan/parallel.h>
*
* @signature void spawn(pool, callable, ...args);
* @param[in,out] pool The @link ThreadPool @endlink to register the new spawned thread in.
* @param[in] callable A callable object (e.g. functor or function) that should be executed by the spawned thread.
* @param args Any number of arguments passed to the callable object.
*
* Emplaces the thread in the <tt>pool</tt> and associates the thread with the callable by passing the <tt>args</tt>
* to the callable instance.
*
* @datarace This function is not thread safe. Concurrent invocations of this function for the same <tt>pool</tt> might
* result in undefined behavior.
*/
template <typename TCallable, typename ...TArgs>
inline void
spawn(ThreadPool & pool,
TCallable callable, TArgs && ...args)
{
pool._mPool.emplace_back(callable, std::forward<TArgs>(args)...);
}
/*!
* @fn ThreadPool#join
* @brief Explicit barrier over the pool.
* @headerfile <seqan/parallel.h>
*
* @signature void join(pool);
* @param[in,out] pool The @link ThreadPool @endlink to be joined.
*
* Allows the user to wait for all registered threads to be finished before the calling thread continues its execution.
*
* @datarace This function is not thread safe. Concurrent invocations of this function for the same <tt>pool</tt> might
* result in undefined behavior.
*/
inline void
join(ThreadPool & me)
{
for_each(std::begin(me._mPool), std::end(me._mPool),
[](auto & t)
{
if (t.joinable())
t.join();
});
}
/*!
* @fn ThreadPool#setCpuAffinity
* @brief Pins the spawned threads in a round-robin fashion.
* @headerfile <seqan/parallel.h>
*
* @signature void setCpuAffinity(pool, cpu, scale);
* @param[in,out] pool The @link ThreadPool @endlink to pin the threads for.
* @param[in] cpu The number of the first cpu to be pinned.
* @param[in] scale A scaling factor to
*
* Iterates over all threads registered in the pool and pins each of them to a cpu in a round-robin fashion.
* Using <tt>cpu</tt> and <tt>scale</tt> the cpu ids for pinning the threads can be configured dynamically.
* @section Possible implementation:
* @code{.cpp}
* cpu * scale % std::thread::hardware_concurrency();
* @endcode
*
* @note This function uses pthread functions on the native thread handle and is only available for linux platforms.
* On all other platforms this function is a no-op.
*
* @datarace This function is not thread safe. Concurrent invocations of this function for the same <tt>pool</tt> might
* result in undefined behavior.
*/
#if defined(__linux__)
inline bool
setCpuAffinity(ThreadPool & me, size_t firstCpu = 0, size_t const scale = 1)
{
SEQAN_ASSERT_GEQ(scale, static_cast<size_t>(1));
bool success{true};
for (auto & t : me._mPool)
{
// Create a cpu_set_t object representing a set of CPUs. Clear it and mark
// only CPU i as set.
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET((firstCpu * scale) % std::thread::hardware_concurrency(), &cpuset);
int rc = pthread_setaffinity_np(t.native_handle(),
sizeof(cpu_set_t), &cpuset);
success &= (rc == 0);
++firstCpu;
}
return success;
}
#else
inline bool
setCpuAffinity(ThreadPool & /*me*/, size_t /*firstCpu = 0*/, size_t const /*scale = 0*/)
{
return false;
}
#endif // defined(__linux__)
} // namespace seqan
#endif // INCLUDE_SEQAN_PARALLEL_PARALLEL_THREAD_POOL_H_
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