volksdata_lua/src/lua_store.c

#include "lua_volksdata.h"


static int l_store_new (lua_State *L)
{
    const VOLK_StoreType store_type = luaL_checkinteger (L, 1);
    const char *id = luaL_optstring (L, 2, NULL);
    const bool clear = lua_toboolean (L, 3);

    VOLK_Store **store_p = lua_newuserdatauv (L, sizeof (*store_p), 1);
    luaL_getmetatable (L, "VOLK.Store");
    lua_setmetatable (L, -2);

    // Set up the store if a function for that is defined.
    if (clear) log_info ("Clearing old store.");
    *store_p = VOLK_store_new (store_type, id, 0, clear);
    LUA_NLCHECK (*store_p, "Error creating back end store.");

    return 1;
}


// This can be called automatically by te garbage collector, or manually.
// It is idempotent.
static int l_store_gc (lua_State *L)
{
    VOLK_Store **sp = luaL_checkudata(L, 1, "VOLK.Store");
    LOG_DEBUG ("Garbage collecting store @%p.", *sp);

    VOLK_store_free (*sp);
    *sp = NULL;

    return 0;
}


static int l_store_size (lua_State *L)
{
    const VOLK_Store **store_p = luaL_checkudata (L, 1, "VOLK.Store");
    lua_pushinteger (L, VOLK_store_size (*store_p));

    return 1;
}


static int l_store_tostring (lua_State *L)
{
    const VOLK_Store *store = *(VOLK_Store **) luaL_checkudata (
            L, 1, "VOLK.Store");
    lua_pushfstring (
            L, "VOLK.Store @%p <%s>: %s",
            store,
            VOLK_store_type_label (store->type),
            store->id);

    return 1;
}


// TODO add transaction handling.


static const luaL_Reg store_lib_fn [] = {
    {"new", l_store_new},

    {NULL}
};


static const luaL_Reg store_lib_meth [] = {
    {"__gc", l_store_gc},
    {"__len", l_store_size},
    {"__tostring", l_store_tostring},

    {"close", l_store_gc},

    {NULL}
};


static const LEnumConst store_enums[] = {
    {"HTABLE", VOLK_STORE_HTABLE},
    {"MDB", VOLK_STORE_MDB},

    {NULL, 0}
};


int luaopen_volksdata_store (lua_State *L)
{
    VOLK_init();  // This is idempotent: no problem calling it multiple times.
    luaL_newmetatable (L, "VOLK.Store");
    lua_pushvalue (L, -1);
    lua_setfield (L, -2, "__index");
    luaL_setfuncs (L, store_lib_meth, 0);

    luaL_newlib (L, store_lib_fn);
    push_int_const (L, store_enums);

    return 1;
}