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/***************************************************************************
* lib/io/request_queue_impl_qwqr.cpp
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2002-2005 Roman Dementiev <dementiev@mpi-sb.mpg.de>
* Copyright (C) 2008, 2009 Andreas Beckmann <beckmann@cs.uni-frankfurt.de>
* Copyright (C) 2009 Johannes Singler <singler@ira.uka.de>
* Copyright (C) 2013 Timo Bingmann <tb@panthema.net>
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
**************************************************************************/
#include <algorithm>
#include <stxxl/bits/common/error_handling.h>
#include <stxxl/bits/io/request_queue_impl_qwqr.h>
#include <stxxl/bits/io/serving_request.h>
#include <stxxl/bits/parallel.h>
#if STXXL_STD_THREADS && STXXL_MSVC >= 1700
#include <windows.h>
#endif
#ifndef STXXL_CHECK_FOR_PENDING_REQUESTS_ON_SUBMISSION
#define STXXL_CHECK_FOR_PENDING_REQUESTS_ON_SUBMISSION 1
#endif
STXXL_BEGIN_NAMESPACE
struct file_offset_match : public std::binary_function<request_ptr, request_ptr, bool>
{
bool operator () (
const request_ptr& a,
const request_ptr& b) const
{
// matching file and offset are enough to cause problems
return (a->get_offset() == b->get_offset()) &&
(a->get_file() == b->get_file());
}
};
request_queue_impl_qwqr::request_queue_impl_qwqr(int n)
: m_thread_state(NOT_RUNNING), m_sem(0)
{
STXXL_UNUSED(n);
start_thread(worker, static_cast<void*>(this), m_thread, m_thread_state);
}
void request_queue_impl_qwqr::add_request(request_ptr& req)
{
if (req.empty())
STXXL_THROW_INVALID_ARGUMENT("Empty request submitted to disk_queue.");
if (m_thread_state() != RUNNING)
STXXL_THROW_INVALID_ARGUMENT("Request submitted to not running queue.");
if (!dynamic_cast<serving_request*>(req.get()))
STXXL_ERRMSG("Incompatible request submitted to running queue.");
if (req.get()->get_type() == request::READ)
{
#if STXXL_CHECK_FOR_PENDING_REQUESTS_ON_SUBMISSION
{
scoped_mutex_lock Lock(m_write_mutex);
if (std::find_if(m_write_queue.begin(), m_write_queue.end(),
bind2nd(file_offset_match(), req) _STXXL_FORCE_SEQUENTIAL)
!= m_write_queue.end())
{
STXXL_ERRMSG("READ request submitted for a BID with a pending WRITE request");
}
}
#endif
scoped_mutex_lock Lock(m_read_mutex);
m_read_queue.push_back(req);
}
else
{
#if STXXL_CHECK_FOR_PENDING_REQUESTS_ON_SUBMISSION
{
scoped_mutex_lock Lock(m_read_mutex);
if (std::find_if(m_read_queue.begin(), m_read_queue.end(),
bind2nd(file_offset_match(), req) _STXXL_FORCE_SEQUENTIAL)
!= m_read_queue.end())
{
STXXL_ERRMSG("WRITE request submitted for a BID with a pending READ request");
}
}
#endif
scoped_mutex_lock Lock(m_write_mutex);
m_write_queue.push_back(req);
}
m_sem++;
}
bool request_queue_impl_qwqr::cancel_request(request_ptr& req)
{
if (req.empty())
STXXL_THROW_INVALID_ARGUMENT("Empty request canceled disk_queue.");
if (m_thread_state() != RUNNING)
STXXL_THROW_INVALID_ARGUMENT("Request canceled to not running queue.");
if (!dynamic_cast<serving_request*>(req.get()))
STXXL_ERRMSG("Incompatible request submitted to running queue.");
bool was_still_in_queue = false;
if (req.get()->get_type() == request::READ)
{
scoped_mutex_lock Lock(m_read_mutex);
queue_type::iterator pos
= std::find(m_read_queue.begin(), m_read_queue.end(),
req _STXXL_FORCE_SEQUENTIAL);
if (pos != m_read_queue.end())
{
m_read_queue.erase(pos);
was_still_in_queue = true;
m_sem--;
}
}
else
{
scoped_mutex_lock Lock(m_write_mutex);
queue_type::iterator pos
= std::find(m_write_queue.begin(), m_write_queue.end(),
req _STXXL_FORCE_SEQUENTIAL);
if (pos != m_write_queue.end())
{
m_write_queue.erase(pos);
was_still_in_queue = true;
m_sem--;
}
}
return was_still_in_queue;
}
request_queue_impl_qwqr::~request_queue_impl_qwqr()
{
stop_thread(m_thread, m_thread_state, m_sem);
}
void* request_queue_impl_qwqr::worker(void* arg)
{
self* pthis = static_cast<self*>(arg);
bool write_phase = true;
for ( ; ; )
{
pthis->m_sem--;
if (write_phase)
{
scoped_mutex_lock WriteLock(pthis->m_write_mutex);
if (!pthis->m_write_queue.empty())
{
request_ptr req = pthis->m_write_queue.front();
pthis->m_write_queue.pop_front();
WriteLock.unlock();
//assert(req->get_reference_count()) > 1);
dynamic_cast<serving_request*>(req.get())->serve();
}
else
{
WriteLock.unlock();
pthis->m_sem++;
if (pthis->m_priority_op == WRITE)
write_phase = false;
}
if (pthis->m_priority_op == NONE || pthis->m_priority_op == READ)
write_phase = false;
}
else
{
scoped_mutex_lock ReadLock(pthis->m_read_mutex);
if (!pthis->m_read_queue.empty())
{
request_ptr req = pthis->m_read_queue.front();
pthis->m_read_queue.pop_front();
ReadLock.unlock();
STXXL_VERBOSE2("queue: before serve request has " << req->get_reference_count() << " references ");
//assert(req->get_reference_count() > 1);
dynamic_cast<serving_request*>(req.get())->serve();
STXXL_VERBOSE2("queue: after serve request has " << req->get_reference_count() << " references ");
}
else
{
ReadLock.unlock();
pthis->m_sem++;
if (pthis->m_priority_op == READ)
write_phase = true;
}
if (pthis->m_priority_op == NONE || pthis->m_priority_op == WRITE)
write_phase = true;
}
// terminate if it has been requested and queues are empty
if (pthis->m_thread_state() == TERMINATING) {
if ((pthis->m_sem--) == 0)
break;
else
pthis->m_sem++;
}
}
pthis->m_thread_state.set_to(TERMINATED);
#if STXXL_STD_THREADS && STXXL_MSVC >= 1700
// Workaround for deadlock bug in Visual C++ Runtime 2012 and 2013, see
// request_queue_impl_worker.cpp. -tb
ExitThread(NULL);
#else
return NULL;
#endif
}
STXXL_END_NAMESPACE
// vim: et:ts=4:sw=4
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