class ugcs::vsm::File_processor

Overview

Processor for working with filesystem I/O. More…

#include <file_processor.h>

class File_processor: public ugcs::vsm::Request_context
{
public:
    // typedefs

    typedef std::shared_ptr<File_processor> Ptr;
    typedef std::weak_ptr<File_processor> Weak_ptr;
    typedef ugcs::vsm::Param_exception<Exception_dummy_struct,> Exception;
    typedef ugcs::vsm::Derived_exception<Exception, Not_found_exception_dummy_struct> Not_found_exception;
    typedef ugcs::vsm::Derived_exception<Exception, Permission_denied_exception_dummy_struct> Permission_denied_exception;
    typedef ugcs::vsm::Derived_exception<Exception, Already_exists_exception_dummy_struct> Already_exists_exception;

    // structs

    struct Already_exists_exception_dummy_struct;
    struct Exception_dummy_struct;
    struct Not_found_exception_dummy_struct;
    struct Permission_denied_exception_dummy_struct;

    // classes

    class Native_controller;
    class Stream;

    // methods

    template <typename... Args>
    static Ptr Create(Args&&... args);

    template <typename... Args>
    static Ptr Get_instance(Args&&... args);

    static FILE* Fopen_utf8(const std::string& name, const std::string& mode);
    static bool Rename_utf8(const std::string& old_name, const std::string& new_name);
    static bool Remove_utf8(const std::string& name);
    static int Access_utf8(const std::string& name, int mode);
    Stream::Ref Open(const std::string& name, const std::string& mode, bool maintain_pos = true);
};

// direct descendants

class Serial_processor;

Inherited Members

public:
    // typedefs

    typedef std::shared_ptr<Request_container> Ptr;
    typedef std::weak_ptr<Request_container> Weak_ptr;
    typedef std::shared_ptr<Request_context> Ptr;
    typedef std::weak_ptr<Request_context> Weak_ptr;

    // enums

    enum Type;

    // classes

    class Request;
    class Request_waiter;

    // methods

    template <typename... Args>
    static Ptr Create(Args&&... args);

    virtual Type Get_type() const;
    bool Check_type(Type mask);
    void Submit_request(Request::Ptr request);
    void Submit_request_locked(Request::Ptr request, Request_waiter::Locker locker);
    int Process_requests(int requests_limit = 0);
    int Process_requests(std::unique_lock<std::mutex>& lock, int requests_limit = 0);
    void Set_waiter(Request_waiter::Ptr waiter);
    Request_waiter::Ptr Get_waiter() const;
    const std::string& Get_name();
    void Enable();
    void Disable();
    bool Is_enabled() const;

    template <typename... Args>
    static Ptr Create(Args&&... args);

    virtual Type Get_type() const;
    Request_container(const std::string& name, Request_waiter::Ptr waiter = Request_waiter::Create());

Detailed Documentation

Processor for working with filesystem I/O.

It is mostly intended for working with special files such as mapped devices in asynchronous mode. It is not so useful for regular files so the user code can use <cstdio> functions for them (unless it does not need asynchronous file operations). Keep in mind that this processor provides asynchronous I/O but not concurrent. All operations for each stream are serialized and never executed in parallel. In case the client code issues concurrent requests it should be aware that file position can be unpredictably updated unless it is explicitly specified.

Typedefs

typedef std::shared_ptr<File_processor> Ptr

Pointer type.

typedef std::weak_ptr<File_processor> Weak_ptr

Pointer type.

typedef ugcs::vsm::Derived_exception<Exception, Not_found_exception_dummy_struct> Not_found_exception

Definition of a new exception type.

typedef ugcs::vsm::Derived_exception<Exception, Permission_denied_exception_dummy_struct> Permission_denied_exception

Definition of a new exception type.

typedef ugcs::vsm::Derived_exception<Exception, Already_exists_exception_dummy_struct> Already_exists_exception

Definition of a new exception type.

Methods

template <typename... Args>
static Ptr Create(Args&&... args)

Create an instance.

template <typename... Args>
static Ptr Get_instance(Args&&... args)

Get global or create new processor instance.

static FILE* Fopen_utf8(const std::string& name, const std::string& mode)

Platform independent method for opening a standard library file handle providing an UTF-8 encoded path and mode.

Parameters:

name	UTF-8 encoded file path to open.
mode	UTF-8 encoded access mode, see standard fopen() method.

Returns:

Valid file handle on success, or nullptr on failure.

static bool Rename_utf8(
    const std::string& old_name,
    const std::string& new_name
    )

Platform independent method for renaming a file providing UTF-8 encoded paths.

Parameters:

old_name	UTF-8 encoded old file name.
new_name	UTF-8 encoded new file name;

Returns:

true on success, false on failure.

static bool Remove_utf8(const std::string& name)

Platform independent method for removing a file providing UTF-8 encoded path.

static int Access_utf8(const std::string& name, int mode)

Platform independent method for checking file access permission providing UTF-8 file name.

Parameters:

name	UTF-8 encoded file name.
mode	Mode as in standard access() method.

Returns:

As in standard access() method.

Stream::Ref Open(
    const std::string& name,
    const std::string& mode,
    bool maintain_pos = true
    )

Open file.

Parameters:

name	File path.
mode	Opening mode similar to the corresponding argument for fopen() function. It supports “x” specifier and do not support “a” and “b” specifiers. All files are opened in binary mode. NOTE: In addition “rx” combination is supported and means create file in read-only mode if it does not exist.
maintain_pos	Indicates whether file position maintenance is required. It should be “false” for devices which do not support seeking. In this case file offset for all I/O operations will be set to zero. In case it is “true” the returned file stream will maintain current position accordingly to the number of bytes read or written.
Invalid_param_exception	if mode string is not valid.
Not_found_exception	if the specified path does not exist when it must exist based on provided opening mode.
Permission_denied_exception	if there is insufficient permissions for file creation.
Already_exists_exception	if new file creation requested (‘x’ specified in opening mode) but the file already exists.
Exception	in case of any other error returned by platform.

Returns:

Created file stream.

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struct ugcs::vsm::Exception::Va_list_overload

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struct ugcs::vsm::File_processor::Already_exists_exception_dummy_struct