lmdb::basic_table< K, V > Struct Template Reference

Helper for grouping typical LMDB DBI options when key and value are fixed types. More...

#include <table.h>

Inheritance diagram for lmdb::basic_table< K, V >:

Collaboration diagram for lmdb::basic_table< K, V >:

Public Types
using	key_type = K
using	value_type = V

Public Member Functions
constexpr	basic_table (const char *name, unsigned flags=0, MDB_cmp_func value_cmp=nullptr) noexcept
Public Member Functions inherited from lmdb::table
expect< MDB_dbi >	open (MDB_txn &write_txn) const noexcept

Static Public Member Functions
static constexpr unsigned	compute_flags (const unsigned flags) noexcept
template<typename U, typename F = U, std::size_t offset = 0>
static expect< F >	get_value (MDB_val value) noexcept
template<typename D>
static expect< key_stream< K, V, D > >	get_key_stream (std::unique_ptr< MDB_cursor, D > cur) noexcept
template<typename D>
static expect< value_stream< V, D > >	get_value_stream (K const &key, std::unique_ptr< MDB_cursor, D > cur) noexcept

Additional Inherited Members
Public Attributes inherited from lmdb::table
char const *const	name
const unsigned	flags
MDB_cmp_func *const	key_cmp
MDB_cmp_func *const	value_cmp

Detailed Description

template<typename K, typename V>
struct lmdb::basic_table< K, V >

Helper for grouping typical LMDB DBI options when key and value are fixed types.

Definition at line 27 of file table.h.

Member Typedef Documentation

key_type

template<typename K, typename V>

using lmdb::basic_table< K, V >::key_type = K

Definition at line 29 of file table.h.

value_type

template<typename K, typename V>

using lmdb::basic_table< K, V >::value_type = V

Definition at line 30 of file table.h.

Constructor & Destructor Documentation

basic_table()

template<typename K, typename V>

lmdb::basic_table< K, V >::basic_table ( const char * name, unsigned flags = 0, MDB_cmp_func value_cmp = nullptr )

inlineexplicitconstexprnoexcept

Definition at line 38 of file table.h.

          : table{name, compute_flags(flags), &lmdb::less<lmdb::native_type<K>>, value_cmp}
        {}

Here is the call graph for this function:

Member Function Documentation

compute_flags()

template<typename K, typename V>

constexpr unsigned lmdb::basic_table< K, V >::compute_flags ( const unsigned flags )

inlinestaticconstexprnoexcept

Returns

Additional LMDB flags based on flags value.

Definition at line 33 of file table.h.

        {
            return flags | ((flags & MDB_DUPSORT) ? MDB_DUPFIXED : 0);
        }

Here is the caller graph for this function:

get_key_stream()

template<typename K, typename V>

template<typename D>

expect< key_stream< K, V, D > > lmdb::basic_table< K, V >::get_key_stream ( std::unique_ptr< MDB_cursor, D > cur )

inlinestaticnoexcept

Precondition

cur != nullptr.

Parameters

cur	Active cursor on table. Returned in object on success, otherwise destroyed.

Returns

A handle to the first key/value in the table linked to cur or an empty key_stream.

Definition at line 78 of file table.h.

        {
            ELECTRONEUM_PRECOND(cur != nullptr);
 
            MDB_val key;
            MDB_val value;
            const int err = mdb_cursor_get(cur.get(), &key, &value, MDB_FIRST);
            if (err)
            {
                if (err != MDB_NOTFOUND)
                    return {lmdb::error(err)};
                cur.reset(); // return empty set
            }
            return key_stream<K, V, D>{std::move(cur)};
        }

Here is the call graph for this function:

get_value()

template<typename K, typename V>

template<typename U, typename F = U, std::size_t offset = 0>

expect< F > lmdb::basic_table< K, V >::get_value ( MDB_val value )

inlinestaticnoexcept

Template Parameters

U	must be same as V; used for sanity checking.
F	is the type within U that is being extracted.
offset	to F within U.

Note

If using F and offset to retrieve a specific field, use ELECTRONEUM_FIELD macro in src/lmdb/util.h which calculates the offset automatically.

Returns

Value of type F at offset within value which has type U.

Definition at line 55 of file table.h.

        {
            static_assert(std::is_same<U, V>(), "bad ELECTRONEUM_FIELD?");
            static_assert(std::is_pod<F>(), "F must be POD");
            static_assert(sizeof(F) + offset <= sizeof(U), "bad field type and/or offset");
 
            if (value.mv_size != sizeof(U))
                return {lmdb::error(MDB_BAD_VALSIZE)};
 
            F out;
            std::memcpy(std::addressof(out), static_cast<char*>(value.mv_data) + offset, sizeof(out));
            return out;
        }

get_value_stream()

template<typename K, typename V>

template<typename D>

expect< value_stream< V, D > > lmdb::basic_table< K, V >::get_value_stream ( K const & key, std::unique_ptr< MDB_cursor, D > cur )

inlinestaticnoexcept

Precondition

cur != nullptr.

Parameters

cur	Active cursor on table. Returned in object on success, otherwise destroyed.

Returns

A handle to the first value at key in the table linked to cur or an empty value_stream.

Definition at line 103 of file table.h.

        {
            ELECTRONEUM_PRECOND(cur != nullptr);
 
            MDB_val key_bytes = lmdb::to_val(key);
            MDB_val value;
            const int err = mdb_cursor_get(cur.get(), &key_bytes, &value, MDB_SET);
            if (err)
            {
                if (err != MDB_NOTFOUND)
                    return {lmdb::error(err)};
                cur.reset(); // return empty set
            }
            return value_stream<V, D>{std::move(cur)};
        }

Here is the call graph for this function:

---

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

• /home/abuild/rpmbuild/BUILD/electroneum-5.1.3.1-build/electroneum-5.1.3.1/src/lmdb/table.h