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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/include/usr/util/impl/threadpool.H $ */
/* */
/* OpenPOWER HostBoot Project */
/* */
/* COPYRIGHT International Business Machines Corp. 2012,2014 */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); */
/* you may not use this file except in compliance with the License. */
/* You may obtain a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or */
/* implied. See the License for the specific language governing */
/* permissions and limitations under the License. */
/* */
/* IBM_PROLOG_END_TAG */
#ifndef __UTIL_IMPL_THREADPOOL_H
#define __UTIL_IMPL_THREADPOOL_H
/** @file threadpool.H
*
* Contains the (mostly) untemplatized implementation details of the
* threadpool.
*
* The idea is that Util::ThreadPool is a templatized class to give the
* user flexibility but most of the details are implemented in a
* non-templatized way to conserve space. When Util::ThreadPool<T> is
* instantiated there is only a small amount of code that is unique to T.
*/
#include <list>
#include <algorithm>
#include <sys/sync.h>
#include <sys/task.h>
namespace Util
{
namespace __Util_ThreadPool_Impl
{
/**
* Export the container types used in the internal ThreadPool
* implementation.
*
* The ThreadPoolImpl here is going to operate on a container of void*'s,
* but the templatized code is going to assume it is operating on a
* container of T*'s. Since an iterator<void*> and iterator<T*> have the
* same behavior, we provide this template here so that the real
* ThreadPool can use the same iterators by typename without knowing if
* they are stored in a list, vector, etc.
*/
template <typename _T>
struct ThreadPoolImplContainer
{
typedef std::list<_T*> worklist_t;
typedef typename std::list<_T*>::iterator worklist_itr_t;
};
/**
* Internal implementation of the thread pool.
*/
class ThreadPoolImpl
{
public:
/** Worklist container type. */
typedef ThreadPoolImplContainer<void>::worklist_t worklist_t;
/** Worklist container iterator type. */
typedef ThreadPoolImplContainer<void>::worklist_itr_t
worklist_itr_t;
/** Typedef of function pointer passed to "start". */
typedef void*(*start_fn_t)(void*);
/** Typedef of function poitner passed to "remove". */
typedef
worklist_itr_t(*order_fn_t)(worklist_itr_t, worklist_itr_t);
/** Simple constructor, call __init to avoid the in-charge and
* not-in-charge construction costs. */
ThreadPoolImpl() { __init(); };
protected:
/** Initialize the object. */
void __init();
/** Insert a work-item onto the work-queue. */
void __insert(void*);
/** Remove the next work item from the work-queue.
*
* Called by worker threads to find the next piece of work.
*
* @param[in] fn - Function to use to order the work by
* priority.
*/
void* __remove(order_fn_t fn);
/** Start the thread-pool.
*
* @param[in] fn - Function to use as the thread entry-point.
* @param[in] instance - "this" to pass to worker threads.
*/
void __start(start_fn_t fn, void* instance);
/** Stop the thread-pool. */
void __shutdown();
/** Outstanding work-list. */
worklist_t iv_worklist;
/** Mutex to protect insert / remove. */
mutex_t iv_mutex;
/** Condition variable to block on empty. */
sync_cond_t iv_condvar;
/** List of worker threads created, to use for joining on
* shutdown */
std::list<tid_t> iv_children;
/** State of object. */
bool iv_shutdown;
};
/** Prototype of 'search' functor against a threadpool. */
template <typename _T, bool nonfifo> struct ThreadPoolWorklistSearch;
/**
* Template specialization of the threadpool search functor for FIFO order.
*/
template <typename _T>
struct ThreadPoolWorklistSearch<_T, false>
{
/**
* Returns the next workitem out of a threadpool list.
*
* Since this is the FIFO specialization, this should just return
* the next item in the list.
*
* @param[in] begin - Iterator to the beginning of the list.
* @param[in] end - Iterator to the end of the list.
*
* @return begin
*/
static typename ThreadPoolImplContainer<_T>::worklist_itr_t
search(typename ThreadPoolImplContainer<_T>::worklist_itr_t begin,
typename ThreadPoolImplContainer<_T>::worklist_itr_t end)
{
return begin;
}
};
/**
* Functor which performs (*a < *b).
*
* Since the items in a worklist are (WorkItem*)'s, they need to be
* dereferenced prior to comparison. This functor performs the
* dereference and comparison operation.
*/
template <typename _T>
struct DerefLessCompare
{
bool operator()(_T* a, _T* b)
{
return ((*a) < (*b));
}
};
/**
* Template specialiation of the threadpool search functor for non-FIFO
* order.
*/
template <typename _T>
struct ThreadPoolWorklistSearch<_T, true>
{
/**
* Returns the next workitem out of a threadpool list.
*
* Since this is the non-FIFO specialization, this should return the
* minimum workitem.
*
* @param[in] begin - Iterator to the beginning of the list.
* @param[in] end - Iterator to the end of the list.
*
* @return Iterator pointing to the minimum entry in the list.
*/
static typename ThreadPoolImplContainer<_T>::worklist_itr_t
search(typename ThreadPoolImplContainer<_T>::worklist_itr_t begin,
typename ThreadPoolImplContainer<_T>::worklist_itr_t end)
{
return std::min_element(begin,end,
DerefLessCompare<_T>());
}
};
};
};
#endif
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