linuxaio_request.cpp

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/***************************************************************************
 * lib/io/linuxaio_request.cpp
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2011 Johannes Singler <[email protected]>
 * Copyright (C) 2014 Timo Bingmann <[email protected]>
 *
 * 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 <stxxl/bits/io/linuxaio_request.h>

#if STXXL_HAVE_LINUXAIO_FILE

#include <stxxl/bits/io/disk_queues.h>
#include <stxxl/bits/verbose.h>
#include <stxxl/bits/common/error_handling.h>

#include <unistd.h>
#include <sys/syscall.h>

STXXL_BEGIN_NAMESPACE

void linuxaio_request::completed(bool posted, bool canceled)
{
 STXXL_VERBOSE_LINUXAIO("linuxaio_request[" << this << "] completed(" <<
 posted << "," << canceled << ")");

 if (!canceled)
 {
 if (m_type == READ)
 stats::get_instance()->read_finished();
 else
 stats::get_instance()->write_finished();
 }
 else if (posted)
 {
 if (m_type == READ)
 stats::get_instance()->read_canceled(m_bytes);
 else
 stats::get_instance()->write_canceled(m_bytes);
 }
 request_with_state::completed(canceled);
}

void linuxaio_request::fill_control_block()
{
 linuxaio_file* af = dynamic_cast<linuxaio_file*>(m_file);

 memset(&cb, 0, sizeof(cb));
 // indirection, so the I/O system retains a counting_ptr reference
 cb.aio_data = reinterpret_cast<__u64>(new request_ptr(this));
 cb.aio_fildes = af->file_des;
 cb.aio_lio_opcode = (m_type == READ) ? IOCB_CMD_PREAD : IOCB_CMD_PWRITE;
 cb.aio_reqprio = 0;
 cb.aio_buf = static_cast<__u64>((unsigned long)(m_buffer));
 cb.aio_nbytes = m_bytes;
 cb.aio_offset = m_offset;
}

//! Submits an I/O request to the OS
//! \returns false if submission fails
bool linuxaio_request::post()
{
 STXXL_VERBOSE_LINUXAIO("linuxaio_request[" << this << "] post()");

 fill_control_block();
 iocb* cb_pointer = &cb;
 // io_submit might considerable time, so we have to remember the current
 // time before the call.
 double now = timestamp();
 linuxaio_queue* queue = dynamic_cast<linuxaio_queue*>(
 disk_queues::get_instance()->get_queue(m_file->get_queue_id())
 );
 long success = syscall(SYS_io_submit, queue->get_io_context(), 1, &cb_pointer);
 if (success == 1)
 {
 if (m_type == READ)
 stats::get_instance()->read_started(m_bytes, now);
 else
 stats::get_instance()->write_started(m_bytes, now);
 }
 else if (success == -1 && errno != EAGAIN)
 STXXL_THROW_ERRNO(io_error, "linuxaio_request::post"
 " io_submit()");

 return success == 1;
}

//! Cancel the request
//!
//! Routine is called by user, as part of the request interface.
bool linuxaio_request::cancel()
{
 STXXL_VERBOSE_LINUXAIO("linuxaio_request[" << this << "] cancel()");

 if (!m_file) return false;

 request_ptr req(this);
 linuxaio_queue* queue = dynamic_cast<linuxaio_queue*>(
 disk_queues::get_instance()->get_queue(m_file->get_queue_id())
 );
 return queue->cancel_request(req);
}

//! Cancel already posted request
bool linuxaio_request::cancel_aio()
{
 STXXL_VERBOSE_LINUXAIO("linuxaio_request[" << this << "] cancel_aio()");

 if (!m_file) return false;

 io_event event;
 linuxaio_queue* queue = dynamic_cast<linuxaio_queue*>(
 disk_queues::get_instance()->get_queue(m_file->get_queue_id())
 );
 long result = syscall(SYS_io_cancel, queue->get_io_context(), &cb, &event);
 if (result == 0) //successfully canceled
 queue->handle_events(&event, 1, true);
 return result == 0;
}

STXXL_END_NAMESPACE

#endif // #if STXXL_HAVE_LINUXAIO_FILE
// vim: et:ts=4:sw=4