Information about an available key value store implementation. More...

#include "kvstore.hpp"

Public Types
enum	bitfield__features : unsigned { none = 1U << 0U , shared_memory = 1U << 1U , history = 1U << 2U , stable_values = 1U << 3U , stable_keys = 1U << 4U , update_deltas = 1U << 5U , atomic_snapshots = 1U << 6U , atomic_transactions = 1U << 7U }
	Features requested, or provided by, this store. More...

using	uri_type = std::basic_string< char >
	The type of the UTF-8 URI used by this store.

using	extent_type = llfio::file_handle::extent_type
	The value extent type used by this store.

using	size_type = llfio::file_handle::size_type
	The memory extent type used by this store.

using	handle_type = llfio::file_handle
	The handle type used by this store.

using	mode = handle_type::mode
	The mode used by this store.

using	creation = handle_type::creation
	The creation used by this store.

using	caching = handle_type::caching
	The kernel caching used by this store.

Public Attributes
const char *	name
	The name of this store implementation.

size_type	min_key_size
	The minimum key size, in bytes, supported.

size_type	max_key_size
	The maximum key size, in bytes, supported.

extent_type	min_value_size
	The minimum value size, in bytes, supported.

extent_type	max_value_size

features	features
	The features this store implementation provides.

int(*	score )(const uri_type &uri, handle_type::mode, handle_type::creation creation)

result< basic_key_value_store >(*	create )(const basic_key_value_store::uri_type &uri, size_type key_size, features _features, mode _mode, creation _creation, caching _caching)

Detailed Description

Information about an available key value store implementation.

Member Enumeration Documentation

◆ bitfield__features

enum kvstore_v1_xxx::basic_key_value_store_info::bitfield__features : unsigned

Features requested, or provided by, this store.

Enumerator
none	Bare key-value store. Very likely to choose a hardware implementation, if one is available.
shared_memory	Use a single shared memory region for storage. Note that keys and value sizes freeze after URI fetch.
history	A certain amount of history of previous valid states of the store is kept such that a previously valid state can always be restored after sudden power loss.
stable_values	Updates do not appear to modify any pinned value.
stable_keys	Updates do not appear to remove any pinned keys.
update_deltas	In-place partial updates are recorded as change deltas.
atomic_snapshots	The ability to pin the value of more than one key in an atomic snapshot.
atomic_transactions	The ability to update many items with dependencies on other items as a single, all-or-nothing, change.

   {
     none = 1U << 0U,                //!< Bare key-value store. Very likely to choose a hardware implementation, if one is available.
     shared_memory = 1U << 1U,       //!< Use a single shared memory region for storage. Note that keys and value sizes freeze after URI fetch.
     history = 1U << 2U,             //!< A certain amount of history of previous valid states of the store is kept such that a previously valid state can always be restored after sudden power loss.
     stable_values = 1U << 3U,       //!< Updates do not appear to modify any pinned value.
     stable_keys = 1U << 4U,         //!< Updates do not appear to remove any pinned keys.
     update_deltas = 1U << 5U,       //!< In-place partial updates are recorded as change deltas.
     atomic_snapshots = 1U << 6U,    //!< The ability to pin the value of more than one key in an atomic snapshot.
     atomic_transactions = 1U << 7U  //!< The ability to update many items with dependencies on other items as a single, all-or-nothing, change.
   }

Member Data Documentation

◆ create

result<basic_key_value_store>(* kvstore_v1_xxx::basic_key_value_store_info::create) (const basic_key_value_store::uri_type &uri, size_type key_size, features _features, mode _mode, creation _creation, caching _caching)

Construct a store implementation.

◆ max_value_size

extent_type kvstore_v1_xxx::basic_key_value_store_info::max_value_size

The maximum value size, in bytes, supported.

◆ score

int(* kvstore_v1_xxx::basic_key_value_store_info::score) (const uri_type &uri, handle_type::mode, handle_type::creation creation)

Examine the specified URI for suitability for this store implementation. Zero means that the URI location is suitable, but the format at that location is not compatible. Negative means the URI location is not possible. Higher positive scores outrank other positive scores.

The documentation for this struct was generated from the following file:

include/kvstore/kvstore.hpp

Public Types