preload_context.hpp

/*
  Copyright 2018-2019, Barcelona Supercomputing Center (BSC), Spain
  Copyright 2015-2019, Johannes Gutenberg Universitaet Mainz, Germany

  This software was partially supported by the
  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).

  This software was partially supported by the
  ADA-FS project under the SPPEXA project funded by the DFG.

  SPDX-License-Identifier: MIT
*/

#ifndef GEKKOFS_PRELOAD_CTX_HPP
#define GEKKOFS_PRELOAD_CTX_HPP

#include <hermes.hpp>
#include <map>
#include <mercury.h>
#include <memory>
#include <vector>
#include <string>

#include <bitset>

/* Forward declarations */
class OpenFileMap;
class Distributor;

namespace gkfs { namespace log {
    struct logger;
}}


struct FsConfig {
    // configurable metadata
    bool atime_state;
    bool mtime_state;
    bool ctime_state;
    bool link_cnt_state;
    bool blocks_state;

    uid_t uid;
    gid_t gid;

    std::string rootdir;

};

enum class RelativizeStatus {
    internal,
    external,
    fd_unknown,
    fd_not_a_dir
};

class PreloadContext {

    static auto constexpr MIN_INTERNAL_FD = MAX_OPEN_FDS - MAX_INTERNAL_FDS;
    static auto constexpr MAX_USER_FDS = MIN_INTERNAL_FD;

    private:
    PreloadContext();

    std::shared_ptr<OpenFileMap> ofm_;
    std::shared_ptr<Distributor> distributor_;
    std::shared_ptr<FsConfig> fs_conf_;

    std::string cwd_;
    std::vector<std::string> mountdir_components_;
    std::string mountdir_;

    std::vector<hermes::endpoint> hosts_;
    uint64_t local_host_id_;

    bool interception_enabled_;

    std::bitset<MAX_INTERNAL_FDS> internal_fds_;
    mutable std::mutex internal_fds_mutex_;
    bool internal_fds_must_relocate_;
    std::bitset<MAX_USER_FDS> protected_fds_;

    public:
    static PreloadContext* getInstance() {
        static PreloadContext instance;
        return &instance;
    }

    PreloadContext(PreloadContext const&) = delete;
    void operator=(PreloadContext const&) = delete;

    void init_logging();
    void mountdir(const std::string& path);
    const std::string& mountdir() const;
    const std::vector<std::string>& mountdir_components() const;

    void cwd(const std::string& path);
    const std::string& cwd() const;

    const std::vector<hermes::endpoint>& hosts() const;
    void hosts(const std::vector<hermes::endpoint>& addrs);
    void clear_hosts();


    uint64_t local_host_id() const;
    void local_host_id(uint64_t id);

    RelativizeStatus relativize_fd_path(int dirfd,
                                        const char * raw_path,
                                        std::string& relative_path,
                                        bool resolve_last_link = true) const;

    bool relativize_path(const char * raw_path, std::string& relative_path, bool resolve_last_link = true) const;
    const std::shared_ptr<OpenFileMap>& file_map() const;

    void distributor(std::shared_ptr<Distributor> distributor);
    std::shared_ptr<Distributor> distributor() const;
    const std::shared_ptr<FsConfig>& fs_conf() const;

    void enable_interception();
    void disable_interception();
    bool interception_enabled() const;

    int register_internal_fd(int fd);
    void unregister_internal_fd(int fd);
    bool is_internal_fd(int fd) const;

    void protect_user_fds();
    void unprotect_user_fds(); 
};


#endif //GEKKOFS_PRELOAD_CTX_HPP