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Class mdbx::env_managed

ClassList > mdbx > env_managed

Managed database environment. More...

  • #include <mdbx.h++>

Inherits the following classes: mdbx::env

Classes

Type Name
struct create_parameters
Additional parameters for creating a new database.

Public Types inherited from mdbx::env

See mdbx::env

Type Name
enum int defrag_control
Control values returned by the defragmentation progress visitor.
typedef ::MDBX_defrag_result_t defrag_result
The result of database defragmentation, see MDBX_defrag_result_t .
enum unsigned durability
Durability level.
enum extra_runtime_option
MDBX environment extra runtime options.
typedef ::MDBX_envinfo info
Information about the environment.
enum unsigned mode
Operation mode.
enum remove_mode
Deletion modes for remove() .
typedef ::MDBX_stat stat
Statistics for a database in the MDBX environment.

Public Static Attributes inherited from mdbx::env

See mdbx::env

Type Name
durability half_synchronous_weak_last = durability::half\_synchronous\_weak\_last
durability lazy_weak_tail = /* multi line expression */
mode nested_transactions = /* multi line expression */
mode readonly = mode::readonly
durability robust_synchronous = /* multi line expression */
durability whole_fragile = /* multi line expression */
mode write_file_io = /* multi line expression */
mode write_mapped_io = /* multi line expression */

Public Functions

Type Name
void close (bool dont_sync=false)
Explicitly closes the environment and release the memory map.
constexpr env_managed () noexcept
Constructs an empty (not opened) managed environment.
env_managed (const ::mdbx::filesystem::path & pathname, const operate_parameters & params, bool accede=true)
Open existing database.
env_managed (const ::std::wstring & pathname, const operate_parameters & params, bool accede=true)
Open existing database (the operate_parameters overload for a wide-string path).
env_managed (const wchar_t * pathname, const operate_parameters & params, bool accede=true)
Open existing database (the operate_parameters overload for a wide-string path).
env_managed (const ::std::string & pathname, const operate_parameters & params, bool accede=true)
Open existing database (the operate_parameters overload for a narrow-string path).
env_managed (const char * pathname, const operate_parameters & params, bool accede=true)
Open existing database (the operate_parameters overload for a C-string path).
env_managed (const ::mdbx::filesystem::path & pathname, const create_parameters & create_params, const operate_parameters & operate_params, bool accede=true)
Create new or open existing database.
env_managed (const ::std::wstring & pathname, const create_parameters & create_params, const operate_parameters & operate_params, bool accede=true)
Create new or open existing database (wide-string path overload).
env_managed (const wchar_t * pathname, const create_parameters & create_params, const operate_parameters & operate_params, bool accede=true)
Create new or open existing database (wide-string path overload).
env_managed (const ::std::string & pathname, const create_parameters & create_params, const operate_parameters & operate_params, bool accede=true)
Create new or open existing database (narrow-string path overload).
env_managed (const char * pathname, const create_parameters & create_params, const operate_parameters & operate_params, bool accede=true)
Create new or open existing database (C-string path overload).
env_managed (env_managed &&) = default
Move constructor.
env_managed (const env_managed &) = delete
env_managed & operator= (env_managed && other) noexcept
Move assignment operator.
env_managed & operator= (const env_managed &) = delete
virtual ~env_managed ()

Public Functions inherited from mdbx::env

See mdbx::env

Type Name
env & copy (const ::mdbx::filesystem::path & destination, bool compactify, bool force_dynamic_size=false)
Make a copy (backup) of an existing environment to the specified path.
env & copy (const ::std::wstring & destination, bool compactify, bool force_dynamic_size=false)
Make a copy (backup) of an existing environment to the specified path.
env & copy (const wchar_t * destination, bool compactify, bool force_dynamic_size=false)
Make a copy (backup) of an existing environment to the specified path.
env & copy (const ::std::string & destination, bool compactify, bool force_dynamic_size=false)
Make a copy (backup) of an existing environment to the specified path.
env & copy (const char * destination, bool compactify, bool force_dynamic_size=false)
Make a copy (backup) of an existing environment to the specified path.
env & copy (filehandle fd, bool compactify, bool force_dynamic_size=false)
Copy an environment to the specified file descriptor.
size_t dbsize_max () const
Returns the maximal database size in bytes for the environment.
size_t dbsize_min () const
Returns the minimal database size in bytes for the environment.
constexpr env () noexcept
Constructs an empty (null) environment.
env (const env &) noexcept
Copy constructor.
env (env_managed &&) = delete
size_t get_pagesize () const
Returns pagesize of this MDBX environment.
const path_char * get_path () const
Return the path that was used for opening the environment.
const MDBX_env * handle () noexcept const
Returns the underlying C handle (read-only).
MDBX_env * handle () noexcept
Returns the underlying C handle.
bool is_cooperative () const
Checks whether the environment is cooperative, i.e. not exclusive.
bool is_empty () const
Checks whether the database is empty.
bool is_exclusive () const
Checks whether the environment is exclusive.
bool is_nested_transactions_available () const
Checks whether nested transactions are available.
bool is_pristine () const
Returns true for a freshly created database, butfalse if at least one transaction was committed.
bool is_readonly () const
Checks whether the environment is read-only.
bool is_readwrite () const
Checks whether the environment is read-write.
bool is_writemap () const
Checks whether the environment uses memory-mapped I/O for writes.
size_t key_max (key_mode mode) const
Returns the maximal key size in bytes for specified keys mode.
size_t key_min (key_mode mode) noexcept const
Returns the minimal key size in bytes for specified keys mode.
constexpr operator MDBX_env * () noexcept
Returns the underlying C handle.
constexpr operator const MDBX_env * () noexcept const
Returns the underlying C handle (read-only).
env & operator= (const env &) noexcept
Copy assignment operator.
env & operator= (env_managed &&) = delete
bool poll_sync_to_disk ()
Performs non-blocking polling of sync-to-disk thresholds.
env & set_sync_period (const duration & period)
Sets relative period since the last unsteady commit to force flush the data buffers to disk, for non-sync durability modes.
duration sync_period () const
Gets relative period since the last unsteady commit that used to force flush the data buffers to disk, for non-sync durability modes.
size_t transaction_size_max () const
Returns the maximal write transaction size (i.e. limit for summary volume of dirty pages) in bytes.
size_t value_max (value_mode mode) const
Returns the maximal value size in bytes for specified values mode.
size_t value_min (value_mode mode) noexcept const
Returns the minimal value size in bytes for specified values mode.

Public Static Functions

Type Name
env_managed open_for_recovery (const char * pathname, unsigned target_meta, bool writeable, unsigned max_maps=2)
Opens an environment instance using a specific meta-page for checking and recovery.
env_managed open_for_recovery (const ::std::string & pathname, unsigned target_meta, bool writeable, unsigned max_maps=2)
Opens an environment instance using a specific meta-page for checking and recovery.
env_managed open_for_recovery (const ::mdbx::filesystem::path & pathname, unsigned target_meta, bool writeable, unsigned max_maps=2)
Opens an environment instance using a specific meta-page for checking and recovery.
env_managed open_for_recovery (const wchar_t * pathname, unsigned target_meta, bool writeable, unsigned max_maps=2)
Opens an environment instance using a specific meta-page for checking and recovery.
env_managed open_for_recovery (const ::std::wstring & pathname, unsigned target_meta, bool writeable, unsigned max_maps=2)
Opens an environment instance using a specific meta-page for checking and recovery.

Public Static Functions inherited from mdbx::env

See mdbx::env

Type Name
size_t default_pagesize () noexcept
Returns default page size for current system/platform.
MDBX_NODISCARD info get_preopen_snapinfo (const ::std::wstring & pathname, MDBX_preopen_flags mode=MDBX_PREOPEN_PROPERLY)
Provides information about a database, including meta-page and geometry, without opening it.
MDBX_NODISCARD info get_preopen_snapinfo (const wchar_t * pathname, MDBX_preopen_flags mode=MDBX_PREOPEN_PROPERLY)
Provides information about a database, including meta-page and geometry, without opening it.
bool remove (const ::mdbx::filesystem::path & pathname, const remove_mode mode=just_remove)
Removes the environment's files in a proper and multiprocess-safe way.
bool remove (const ::std::wstring & pathname, const remove_mode mode=just_remove)
Removes the environment's files in a proper and multiprocess-safe way.
bool remove (const wchar_t * pathname, const remove_mode mode=just_remove)
Removes the environment's files in a proper and multiprocess-safe way.
bool remove (const ::std::string & pathname, const remove_mode mode=just_remove)
Removes the environment's files in a proper and multiprocess-safe way.
bool remove (const char * pathname, const remove_mode mode=just_remove)
Removes the environment's files in a proper and multiprocess-safe way.

Protected Attributes inherited from mdbx::env

See mdbx::env

Type Name
MDBX_env * handle_ = {nullptr}
The underlying C environment handle, null for an empty instance.

Detailed Description

As other managed classes, env_managed destroys the represented underlying object from the own class destructor, but disallows copying and assignment for instances.

An environment supports multiple key-value tables (aka key-value spaces or maps), all residing in the same shared-memory mapped file.

Public Functions Documentation

function close

Explicitly closes the environment and release the memory map. 

void mdbx::env_managed::close (
    bool dont_sync=false
)

Only a single thread may call this function. All transactions, tables, and cursors must already be closed before calling this function. Attempts to use any such handles after calling this function will cause a SIGSEGV. The environment handle will be freed and must not be used again after this call.

Parameters:

  • dont_sync The dont_sync flag, if non-zero the last checkpoint will be kept "as is" and may be still "weak" in the env::durability::lazy_weak_tail or env::durability::whole_fragile modes. Such "weak" checkpoint will be ignored on opening next time, and transactions since the last non-weak checkpoint (meta-page update) will rolledback for consistency guarantee.

function env_managed [2/14]

Constructs an empty (not opened) managed environment. 

constexpr mdbx::env_managed::env_managed () noexcept

function env_managed [3/14]

Open existing database. 

mdbx::env_managed::env_managed (
    const ::mdbx::filesystem::path & pathname,
    const operate_parameters & params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with, instead of failing on a mismatch.

Exception:

function env_managed [4/14]

Open existing database (the operate_parameters overload for a wide-string path).

mdbx::env_managed::env_managed (
    const ::std::wstring & pathname,
    const operate_parameters & params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [5/14]

Open existing database (the operate_parameters overload for a wide-string path).

explicit mdbx::env_managed::env_managed (
    const wchar_t * pathname,
    const operate_parameters & params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [6/14]

Open existing database (the operate_parameters overload for a narrow-string path).

mdbx::env_managed::env_managed (
    const ::std::string & pathname,
    const operate_parameters & params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [7/14]

Open existing database (the operate_parameters overload for a C-string path).

explicit mdbx::env_managed::env_managed (
    const char * pathname,
    const operate_parameters & params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [8/14]

Create new or open existing database. 

mdbx::env_managed::env_managed (
    const ::mdbx::filesystem::path & pathname,
    const create_parameters & create_params,
    const operate_parameters & operate_params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • create_params The create parameters, see create_parameters.
  • operate_params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with, instead of failing on a mismatch.

Exception:

function env_managed [9/14]

Create new or open existing database (wide-string path overload). 

mdbx::env_managed::env_managed (
    const ::std::wstring & pathname,
    const create_parameters & create_params,
    const operate_parameters & operate_params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • create_params The create parameters, see create_parameters.
  • operate_params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [10/14]

Create new or open existing database (wide-string path overload). 

explicit mdbx::env_managed::env_managed (
    const wchar_t * pathname,
    const create_parameters & create_params,
    const operate_parameters & operate_params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • create_params The create parameters, see create_parameters.
  • operate_params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [11/14]

Create new or open existing database (narrow-string path overload). 

mdbx::env_managed::env_managed (
    const ::std::string & pathname,
    const create_parameters & create_params,
    const operate_parameters & operate_params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • create_params The create parameters, see create_parameters.
  • operate_params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [12/14]

Create new or open existing database (C-string path overload). 

explicit mdbx::env_managed::env_managed (
    const char * pathname,
    const create_parameters & create_params,
    const operate_parameters & operate_params,
    bool accede=true
)

Parameters:

  • pathname The path to the database.
  • create_params The create parameters, see create_parameters.
  • operate_params The operate parameters, see operate_parameters.
  • accede Open with the parameters the database was created with.

Exception:

function env_managed [13/14]

Move constructor. 

mdbx::env_managed::env_managed (
    env_managed &&
) = default

function env_managed [14/14]

mdbx::env_managed::env_managed (
    const env_managed &
) = delete

function operator=

Move assignment operator. 

env_managed & mdbx::env_managed::operator= (
    env_managed && other
) noexcept

Parameters:

  • other The source managed environment to be moved from.

Returns:

A reference to this instance.

function operator=

env_managed & mdbx::env_managed::operator= (
    const env_managed &
) = delete

function ~env_managed

virtual mdbx::env_managed::~env_managed ()

Public Static Functions Documentation

function open_for_recovery [1/5]

Opens an environment instance using a specific meta-page for checking and recovery. 

static env_managed mdbx::env_managed::open_for_recovery (
    const char * pathname,
    unsigned target_meta,
    bool writeable,
    unsigned max_maps=2
)

Creates a new environment and opens it in the recovery mode, bypassing the regular consistency checks. Mostly an internal API for the mdbx_chk utility and subject to change; use only when you know what you are doing. The opened environment may be used e.g. with env::chk() and env::turn_for_recovery().

Parameters:

  • pathname The path to the database file.
  • target_meta The number of the meta-page to use (0..2), or any value for the default behavior.
  • writeable Whether to open in read-write mode.
  • max_maps The maximum number of named tables/maps, must be set before opening; zero means the library default. The recovery tooling uses 2 (MainDB+GC).

Returns:

The opened managed environment.

See also: mdbx_env_open_for_recovery()

function open_for_recovery [2/5]

Opens an environment instance using a specific meta-page for checking and recovery. 

static env_managed mdbx::env_managed::open_for_recovery (
    const ::std::string & pathname,
    unsigned target_meta,
    bool writeable,
    unsigned max_maps=2
)

Parameters:

  • pathname The path to the database file.
  • target_meta The number of the meta-page to use (0..2), or any value for the default behavior.
  • writeable Whether to open in read-write mode.
  • max_maps The maximum number of named tables/maps.

Returns:

The opened managed environment.

function open_for_recovery [3/5]

Opens an environment instance using a specific meta-page for checking and recovery. 

static env_managed mdbx::env_managed::open_for_recovery (
    const ::mdbx::filesystem::path & pathname,
    unsigned target_meta,
    bool writeable,
    unsigned max_maps=2
)

Parameters:

  • pathname The path to the database file.
  • target_meta The number of the meta-page to use (0..2), or any value for the default behavior.
  • writeable Whether to open in read-write mode.
  • max_maps The maximum number of named tables/maps.

Returns:

The opened managed environment.

function open_for_recovery [4/5]

Opens an environment instance using a specific meta-page for checking and recovery. 

static env_managed mdbx::env_managed::open_for_recovery (
    const wchar_t * pathname,
    unsigned target_meta,
    bool writeable,
    unsigned max_maps=2
)

Parameters:

  • pathname The path to the database file.
  • target_meta The number of the meta-page to use (0..2), or any value for the default behavior.
  • writeable Whether to open in read-write mode.
  • max_maps The maximum number of named tables/maps.

Returns:

The opened managed environment.

function open_for_recovery [5/5]

Opens an environment instance using a specific meta-page for checking and recovery. 

static env_managed mdbx::env_managed::open_for_recovery (
    const ::std::wstring & pathname,
    unsigned target_meta,
    bool writeable,
    unsigned max_maps=2
)

Parameters:

  • pathname The path to the database file.
  • target_meta The number of the meta-page to use (0..2), or any value for the default behavior.
  • writeable Whether to open in read-write mode.
  • max_maps The maximum number of named tables/maps.

Returns:

The opened managed environment.

The documentation for this class was generated from the following file mdbx.h++