aio_provider.h

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Microsoft Corporation
 * 
 * -=- Robust Distributed System Nucleus (rDSN) -=- 
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/*
 * Description:
 *     define the interface for disk operation provider 
 *
 * Revision history:
 *     Mar., 2015, @imzhenyu (Zhenyu Guo), first version
 *     xxxx-xx-xx, author, fix bug about xxx
 */

# pragma once

# include <dsn/tool-api/task.h>
# include <dsn/utility/dlib.h>

namespace dsn {

class disk_engine;
class service_node;
class task_worker_pool;
class task_queue;

# if defined(_WIN32)
# define DSN_INVALID_FILE_HANDLE ((dsn_handle_t)(uintptr_t)0)
# else
# define DSN_INVALID_FILE_HANDLE ((dsn_handle_t)(uintptr_t)-1)
# endif

//
// !!! all threads must be started with task::set_tls_dsn_context(null, provider->node());
//
class aio_provider
{
public:
    template <typename T> static aio_provider* create(disk_engine* disk, aio_provider* inner_provider)
    {
        return new T(disk, inner_provider);
    }

    typedef aio_provider* (*factory)(disk_engine*, aio_provider*);

public:
    DSN_API aio_provider(disk_engine* disk, aio_provider* inner_provider);
    virtual ~aio_provider() {}
    DSN_API service_node* node() const;

    // return DSN_INVALID_FILE_HANDLE if failed
    virtual dsn_handle_t open(const char* file_name, int flag, int pmode) = 0;
    virtual error_code   close(dsn_handle_t fh) = 0;
    virtual error_code   flush(dsn_handle_t fh) = 0;
    virtual void         aio(aio_task* aio) = 0;
    virtual disk_aio*    prepare_aio_context(aio_task*) = 0;

    virtual void start(io_modifer& ctx) = 0;

protected:
    DSN_API void complete_io(aio_task* aio, error_code err, uint32_t bytes, int delay_milliseconds = 0);

private:
    disk_engine *_engine;
};

} // end namespace