src/meta/meta_state_service.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.
 */

#pragma once

#include <functional>
#include <memory>
#include <string>
#include <vector>

#include "runtime/task/future_types.h"
#include "runtime/task/task.h"
#include "runtime/task/task_code.h"
#include "utils/autoref_ptr.h"
#include "utils/blob.h"
#include "utils/error_code.h"

namespace dsn {
class task_tracker;

namespace dist {
typedef std::function<void(error_code ec, const blob &val)> err_value_callback;
typedef future_task<error_code, blob> err_value_future;
typedef dsn::ref_ptr<err_value_future> err_value_future_ptr;

typedef std::function<void(error_code ec, const std::vector<std::string> &ret_strv)>
    err_stringv_callback;
typedef future_task<error_code, std::vector<std::string>> err_stringv_future;
typedef dsn::ref_ptr<err_stringv_future> err_stringv_future_ptr;

// The interface of the reliable meta state service.
// It is usually for storing meta state of dist systems, such as membership.
class meta_state_service
{
public:
    template <typename T>
    static meta_state_service *create()
    {
        return new T();
    }

    typedef meta_state_service *(*factory)();

public:
    /* providers should implement this to support transaction */
    class transaction_entries
    {
    public:
        virtual ~transaction_entries() {}
        virtual error_code create_node(const std::string &node, const blob &value = blob()) = 0;
        virtual error_code delete_node(const std::string &node) = 0;
        virtual error_code set_data(const std::string &node, const blob &value = blob()) = 0;

        virtual error_code get_result(unsigned int entry_index) = 0;
    };

public:
    virtual ~meta_state_service() {}
    /*
     * initialization work
     */
    virtual error_code initialize(const std::vector<std::string> &args) = 0;

    /*
     * finalize work
     */
    virtual error_code finalize() = 0;

    /*
     * create a transaction_entries structure
     * capacity: the maximum entries the structure can hold
     */
    virtual std::shared_ptr<transaction_entries> new_transaction_entries(unsigned int capacity) = 0;

    /*
     * submit transaction, it should be all succeeded or all failed
     * cb_code: the task code specifies where to execute the callback
     * cb_transaction: callback, ec to indicate success or failure reason
     * tracker: to track (wait/cancel) whether the callback is executed
     */
    virtual task_ptr submit_transaction(const std::shared_ptr<transaction_entries> &entries,
                                        task_code cb_code,
                                        const err_callback &cb_transaction,
                                        dsn::task_tracker *tracker = nullptr) = 0;

    /*
     * create a dir node
     * node: the dir name with full path
     * cb_code: the task code specifies where to execute the callback
     * cb_create: create callback, ec to indicate success or failure reason
     * value: the data value to store in the node
     * tracker: to track (wait/cancel) whether the callback is executed
     */
    virtual task_ptr create_node(const std::string &node,
                                 task_code cb_code,
                                 const err_callback &cb_create,
                                 const blob &value = blob(),
                                 dsn::task_tracker *tracker = nullptr) = 0;
    /*
     * delete a dir, the directory may be empty or not
     * node: the dir name with full path
     * recursively_delete: true for recursively delete non-empty node,
     *                     false for failure
     * cb_code: the task code specifies where to execute the callback
     * cb_delete: delete callback, ec to indicate success or failure reason
     */
    virtual task_ptr delete_node(const std::string &node,
                                 bool recursively_delete,
                                 task_code cb_code,
                                 const err_callback &cb_delete,
                                 dsn::task_tracker *tracker = nullptr) = 0;
    /*
     * check if the node dir exists
     * node: the dir name with full path
     * cb_code: the task code specifies where to execute the callback
     * cb_exist: callback to indicate the check result
     */
    virtual task_ptr node_exist(const std::string &node,
                                task_code cb_code,
                                const err_callback &cb_exist,
                                dsn::task_tracker *tracker = nullptr) = 0;
    /*
     * get the data in node
     * node: dir name with full path
     * cb_code: the task code specifies where to execute the callback
     * cb_get_data: callback. If success, ec indicate the success and
     *              node data is returned in ret_str
     *              or-else user get the fail reason in ec
     */
    virtual task_ptr get_data(const std::string &node,
                              task_code cb_code,
                              const err_value_callback &cb_get_data,
                              dsn::task_tracker *tracker = nullptr) = 0;
    /*
     * set the data of the node
     * node: dir name with full path
     * value: the value
     * cb_code: the task code specifies where to execute the callback
     * cb_set_data: the callback to indicate the set result
     */
    virtual task_ptr set_data(const std::string &node,
                              const blob &value,
                              task_code cb_code,
                              const err_callback &cb_set_data,
                              dsn::task_tracker *tracker = nullptr) = 0;
    /*
     * get all childrens of a node
     * node: dir name with full path
     * cb_code: the task code specifies where to execute the callback
     * cb_get_children: if success, ret_strv store the node names of children
     */
    virtual task_ptr get_children(const std::string &node,
                                  task_code cb_code,
                                  const err_stringv_callback &cb_get_children,
                                  dsn::task_tracker *tracker = nullptr) = 0;
};
}
}