plluaspi.c

/*
 * plluaspi.c: PL/Lua SPI
 * Author: Luis Carvalho <lexcarvalho at gmail.com>
 * Please check copyright notice at the bottom of pllua.h
 * $Id: plluaspi.c,v 1.19 2008/03/31 22:57:45 carvalho Exp $
 */

#include "pllua.h"
#include "pllua_xact_cleanup.h"
#include "pllua_errors.h"

#ifndef SPI_prepare_cursor
#define SPI_prepare_cursor(cmd, nargs, argtypes, copts) \
  SPI_prepare(cmd, nargs, argtypes)
#endif

#define SPI_plan void
static const char PLLUA_BUFFER[] = "luaP_Buffer";
static const char PLLUA_TUPTABLE[] = "luaP_Tuptable";
static const char PLLUA_TUPLEMT[] = "tuple";
static const char PLLUA_P_TUPLEMT[] = "ptuple";
static const char PLLUA_PLANMT[] = "plan";
static const char PLLUA_CURSORMT[] = "cursor";
static const char PLLUA_TUPTABLEMT[] = "tupletable";

#include "rtupdesc.h"

typedef struct luaP_Tuple {
  int changed;
  Oid relid;
  HeapTuple tuple;
  TupleDesc tupdesc;
  Datum *value;
  bool *null;
  RTupDesc *rtupdesc;
} luaP_Tuple;

typedef struct luaP_Tuptable {
  int size;
  Portal cursor;
  SPITupleTable *tuptable;
  TupleDesc tupdesc;
  RTupDesc *rtupdesc;
} luaP_Tuptable;

typedef struct luaP_Cursor {
  Portal cursor;
  RTupDesc *rtupdesc;
  void *tupleQueue;
  void *resptr;
} luaP_Cursor;

typedef struct luaP_Plan {
  int nargs;
  int issaved;
  SPI_plan *plan;
  Oid type[1];
} luaP_Plan;


/* ======= Utils ======= */

static int luaP_typeerror (lua_State *L, int narg, const char *tname) {
  const char *msg = lua_pushfstring(L, "%s expected, got %s",
      tname, luaL_typename(L, narg));
  return luaL_argerror(L, narg, msg);
}

#define luaP_getfield(L, s) \
  lua_pushlightuserdata((L), (void *)(s)); \
  lua_rawget((L), LUA_REGISTRYINDEX)

static void luaP_newmetatable (lua_State *L, const char *tname) {
  lua_newtable(L);
  lua_pushlightuserdata(L, (void *) tname);
  lua_pushvalue(L, -2);
  lua_rawset(L, LUA_REGISTRYINDEX);
}

void *luaP_toudata (lua_State *L, int ud, const char *tname) {
  void *p = lua_touserdata(L, ud);
  if (p != NULL) { /* value is userdata? */
    if (lua_getmetatable(L, ud)) { /* does it have a metatable? */
      luaP_getfield(L, tname); /* get metatable */
      if (lua_rawequal(L, -1, -2)) { /* MTs match? */
        lua_pop(L, 2); /* MTs */
        return p;
      }
    }
  }
  return NULL;
}

static void *luaP_checkudata (lua_State *L, int ud, const char *tname) {
  void *p = luaP_toudata(L, ud, tname);
  if (p == NULL) luaP_typeerror(L, ud, tname);
  return p;
}

void luaP_pushdesctable (lua_State *L, TupleDesc desc) {
  int i;
  lua_newtable(L);
  for (i = 0; i < desc->natts; i++) {
    lua_pushstring(L, NameStr(desc->attrs[i]->attname));
    lua_pushinteger(L, i);
    lua_rawset(L, -3); /* t[att] = i */
  }
}

static void luaP_pushtuple_cmn (lua_State *L, HeapTuple tuple,
                      int readonly, RTupDesc* rtupdesc) {
    luaP_Tuple *t;
    TupleDesc tupleDesc;
    int i, n;

    BEGINLUA;
    tupleDesc = rtupdesc->tupdesc;
    n = tupleDesc->natts;

    t = lua_newuserdata(L, sizeof(luaP_Tuple)
                        + n * (sizeof(Datum) + sizeof(bool)));

    t->value = (Datum *) (t + 1);
    t->null = (bool *) (t->value + n);
    t->rtupdesc = rtupdesc_ref(rtupdesc);
    for (i = 0; i < n; i++) {

        bool isnull;
        t->value[i] = heap_getattr(tuple, tupleDesc->attrs[i]->attnum, tupleDesc,
                                   &isnull);
        t->null[i] = isnull;
    }

    if (readonly) {
        t->changed = -1;
    }
    else {
        t->changed = 0;
    }

    t->tupdesc = 0;

    t->relid = 0;
    t->tuple = tuple;
    luaP_getfield(L, PLLUA_TUPLEMT);
    lua_setmetatable(L, -2);
    ENDLUAV(1);
}
static luaP_Tuple* luaP_PTuple_rawctr(lua_State * L, HeapTuple tuple, int readonly, RTupDesc* rtupdesc);
static luaP_Tuple* luaP_pushPTuple(lua_State * L, size_t size, luaP_Tuple *ptr);
#define LUAP_pushtuple_from_ptr(L,t) luaP_pushPTuple(L,0,t)

void
luaP_pushrecord(lua_State *L, Datum record){
	HeapTupleHeader	header = DatumGetHeapTupleHeader(record);
	TupleDesc tupdesc;
	HeapTupleData tuple;
	RTupDesc *shared_desc;

	PG_TRY();
	{
		tupdesc = lookup_rowtype_tupdesc(HeapTupleHeaderGetTypeId(header),
						 HeapTupleHeaderGetTypMod(header));
		/* Build a temporary HeapTuple control structure */
		tuple.t_len = HeapTupleHeaderGetDatumLength(header);
		ItemPointerSetInvalid(&(tuple.t_self));
		tuple.t_tableOid = InvalidOid;
		tuple.t_data = header;

		shared_desc = rtupdesc_ctor(L, tupdesc);
		luaP_pushtuple_cmn(L, &tuple, true, shared_desc);
		rtupdesc_unref(shared_desc);

		ReleaseTupleDesc(tupdesc);
	}
	PG_CATCH();
	{
		luaL_error(L, "record to lua error");
	}
	PG_END_TRY();
}

////////////////////////////////////////////////////////////////////////////////
#define FETCH_CSR_Q 50
#define TUPLE_QUEUE_SIZE FETCH_CSR_Q + 1
typedef struct {
int head, tail;
luaP_Tuple* data[TUPLE_QUEUE_SIZE];
} TupleQueue, *TupleQueuePtr;

static TupleQueuePtr tq_initQueue(lua_State *L) {
    TupleQueuePtr qp;
    MTOLUA(L);
    qp = (TupleQueuePtr) palloc(sizeof(TupleQueue));
    MTOPG;
    qp -> head = qp -> tail = 0;
    return qp;
}
static int tq_isempty(TupleQueuePtr Q) {
    return (Q -> head == Q -> tail);
}

static void tq_enqueue(TupleQueuePtr Q, luaP_Tuple* n) {
    if (Q -> tail == TUPLE_QUEUE_SIZE - 1)
        Q -> tail = 0;
    else
        ++(Q -> tail);
    if (Q -> tail == Q -> head) { //Queue is full
        return;
    }
    Q -> data[Q -> tail] = n;
}

static luaP_Tuple* tq_dequeue(TupleQueuePtr Q) {
    if (tq_isempty(Q)) {
        return NULL;
    }
    if (Q -> head == TUPLE_QUEUE_SIZE - 1)
        Q -> head = 0;
    else
        ++(Q -> head);
    return Q -> data[Q -> head];
}
#undef TUPLE_QUEUE_SIZE

static int luaP_rowsaux (lua_State *L) {
    luaP_Cursor *c;
    luaP_Tuple* t;
    unsigned int i;
    uint32		processed = 0;

    BEGINLUA;
    c = (luaP_Cursor *) lua_touserdata(L, lua_upvalueindex(1));

    if (c->tupleQueue && tq_isempty(c->tupleQueue)){
        pfree(c->tupleQueue);
        c->tupleQueue = NULL;
    }

    if (c->tupleQueue == NULL){


    PLLUA_PG_CATCH_RETHROW(
      SPI_cursor_fetch(c->cursor, 1, FETCH_CSR_Q);
		);

        if (SPI_processed == 0){
            SPI_freetuptable(SPI_tuptable);
            c->rtupdesc = rtupdesc_unref(c->rtupdesc);
            c->resptr = unregister_resource(c->resptr);
            SPI_cursor_close(c->cursor);
            c->cursor = NULL;
            lua_pushnil(L);
            ENDLUAV(1);
            return 1;
        }
        if(c->rtupdesc == NULL){
            c->rtupdesc = rtupdesc_ctor(L,SPI_tuptable->tupdesc);
        }
        c->tupleQueue = tq_initQueue(L);
        for (i = 0; i < SPI_processed; i++)
        {
            HeapTuple	tuple = SPI_tuptable->vals[i];
            t = luaP_PTuple_rawctr(L, tuple, 1, c->rtupdesc);
            tq_enqueue(c->tupleQueue, t);
            processed++;
        }
        SPI_freetuptable(SPI_tuptable);

    }

    t = tq_dequeue(c->tupleQueue);

    LUAP_pushtuple_from_ptr(L, t);

    ENDLUAV(1);
    return 1;
}
#undef FETCH_CSR_Q

////////////////////////////////////////////////////////////////////////////////


/* ======= Buffer ======= */

luaP_Buffer *luaP_getbuffer (lua_State *L, int n) {
  int i;
  luaP_Buffer *b;
  luaP_getfield(L, PLLUA_BUFFER);
  b = (luaP_Buffer *) lua_touserdata(L, -1);
  lua_pop(L, 1);
  if (b == NULL || n > b->size) { /* resize? */
    lua_pushlightuserdata(L, (void *) PLLUA_BUFFER);
    b = (luaP_Buffer *) lua_newuserdata(L, sizeof(luaP_Buffer)
        + n * (sizeof(Datum) + sizeof(char)));
    b->size = n;
    b->value = (Datum *) (b + 1);
    b->null = (char *) (b->value + n);
    lua_rawset(L, LUA_REGISTRYINDEX);
  }
  for (i = 0; i < n; i++) {
    b->value[i] = 0;
    b->null[i] = 'n';
  }
  return b;
}

static void luaP_fillbuffer (lua_State *L, int pos, Oid *type,
    luaP_Buffer *b) {
  lua_pushnil(L);
  while (lua_next(L, pos)) {
    int k = lua_tointeger(L, -2);
    if (k > 0) {
      bool isnull;
      k--; /* zero based */
      b->value[k] = luaP_todatum(L, type[k], 0, &isnull, -1);
      b->null[k] = (isnull) ? 'n' : ' ';
    }
    lua_pop(L, 1);
  }
}

static void cursor_cleanup_p(void *d, int gccall){
    luaP_Cursor *c = (luaP_Cursor *)d;
    if (c->tupleQueue){
        luaP_Tuple* t = tq_dequeue(c->tupleQueue);
        while(t){
            pfree(t);
            t = tq_dequeue(c->tupleQueue);
        }
        c->tupleQueue  = NULL;

        c->rtupdesc = rtupdesc_unref(c->rtupdesc);
    }
    if (gccall == 0)
        c->resptr = NULL;//if garbage collected
    else
        c->resptr = unregister_resource(c->resptr);//transaction end
}

static void cursor_cleanup(void *d){
    cursor_cleanup_p(d,0);
}

static int luaP_cursorgc (lua_State *L) {
    luaP_Cursor *c = (luaP_Cursor *) lua_touserdata(L, 1);
    if (c->tupleQueue){
        cursor_cleanup_p(c, 1);

        if (PortalIsValid(c->cursor) && (c->cursor->status == PORTAL_READY)){
            c->resptr = unregister_resource(c->resptr);
            SPI_cursor_close(c->cursor);
        }
    }
    return 0;
}
/* ======= Tuple ======= */
static int luaP_tuplegc (lua_State *L) {
    luaP_Tuple *t = (luaP_Tuple *) lua_touserdata(L, 1);
    rtupdesc_unref(t->rtupdesc);
    return 0;
}
static luaP_Tuple* luaP_PTuple_rawctr(lua_State * L, HeapTuple tuple, int readonly, RTupDesc* rtupdesc){
    luaP_Tuple *t;
    TupleDesc tupleDesc;
    int i, n;

    tupleDesc = rtupdesc->tupdesc;
    n = tupleDesc->natts;
    MTOLUA(L);
    t = palloc(sizeof(luaP_Tuple) + n * (sizeof(Datum) + sizeof(bool)));
    MTOPG;
    t->value = (Datum *) (t + 1);
    t->null = (bool *) (t->value + n);
    t->rtupdesc = rtupdesc_ref(rtupdesc);
    for (i = 0; i < n; i++) {
        bool isnull;
        t->value[i] = heap_getattr(tuple, tupleDesc->attrs[i]->attnum, tupleDesc,
                                   &isnull);
        t->null[i] = isnull;
    }

    if (readonly) {
        t->changed = -1;
    }
    else {
        t->changed = 0;
    }

    t->tupdesc = 0;

    t->relid = 0;
    t->tuple = tuple;
    return t;
}

static luaP_Tuple* luaP_pushPTuple(lua_State * L, size_t size, luaP_Tuple *ptr)
{
    luaP_Tuple ** udata = (luaP_Tuple **)lua_newuserdata(L, sizeof(luaP_Tuple *));
    if (ptr == NULL){
        MTOLUA(L);
        *udata = palloc(size);
        MTOPG;
    }else{
        *udata = ptr;
    }
    luaP_getfield(L, PLLUA_P_TUPLEMT);
    lua_setmetatable(L, -2);
    return *udata;
}

static int luaP_p_tuplegc (lua_State *L) {
    luaP_Tuple *t = *(luaP_Tuple **) lua_touserdata(L, 1);
    rtupdesc_unref(t->rtupdesc);
    pfree(t);
    return 0;
}

static int luaP_p_tupleindex (lua_State *L) {
    const char *name;
    int i =-1;
    int idx = -1;
    luaP_Tuple *t = *(luaP_Tuple **) lua_touserdata(L, 1);

    if (lua_type(L, 2) == LUA_TNUMBER){
        i = (int)lua_tonumber(L, 2);
        if (t->rtupdesc){
            TupleDesc tupleDesc = rtupdesc_gettup(t->rtupdesc);
            i= i-1; //Lua[1] == C[0]
            if (tupleDesc == NULL){
                ereport(WARNING, (errmsg("access to lost tuple desc at index %i", i+1)));
                lua_pushnil(L);
                return 1;
            }
            if ((i >= 0)&&(i < tupleDesc->natts)) {
                if (!t->null[i])
                    luaP_pushdatum(L, t->value[i], tupleDesc->attrs[i]->atttypid);
                else lua_pushnil(L);
            }
            else {
                //ereport(WARNING, (errmsg("tuple has no field at index %i", i+1)));
                //lua_pushnil(L);
                return luaL_error(L, "tuple has no field at index %d", i+1);
            }
            return 1;
        }
        lua_pushnil(L);
        return 1;
    }

    name = luaL_checkstring(L, 2);

    if (t->rtupdesc){
        TupleDesc tupleDesc = rtupdesc_gettup(t->rtupdesc);
        if (tupleDesc == NULL){
            ereport(WARNING, (errmsg("access to lost tuple desc at  '%s'", name)));
            lua_pushnil(L);
            return 1;
        }
        for (i = 0; i< tupleDesc->natts; ++i){

            if (strcmp(NameStr(tupleDesc->attrs[i]->attname),name) == 0){
                idx = i;
                break;
            }
        }
        i = idx;
        if (i >= 0) {
            if (!t->null[i])
                luaP_pushdatum(L, t->value[i], tupleDesc->attrs[i]->atttypid);
            else lua_pushnil(L);
        }
        else {
            //ereport(WARNING, (errmsg("tuple has no field '%s'", name)));
            //lua_pushnil(L);
            return luaL_error(L, "tuple has no field '%s'", name);

        }
        return 1;
    }
    lua_pushnil(L);
    return 1;
}

static int luaP_tupleindex (lua_State *L) {
  luaP_Tuple *t = (luaP_Tuple *) lua_touserdata(L, 1);
  const char *name = luaL_checkstring(L, 2);
  int i =-1;
  int idx = -1;
  if (t->rtupdesc){
      TupleDesc tupleDesc = rtupdesc_gettup(t->rtupdesc);
      if (tupleDesc == NULL){
          ereport(WARNING, (errmsg("access to lost tuple desc at  '%s'", name)));
          lua_pushnil(L);
          return 1;
      }
      for (i = 0; i< tupleDesc->natts; ++i){

          if (strcmp(NameStr(tupleDesc->attrs[i]->attname),name) == 0){
              idx = i;
              break;
          }
      }
      i = idx;
      if (i >= 0) {
          if (!t->null[i])
            luaP_pushdatum(L, t->value[i], tupleDesc->attrs[i]->atttypid);
          else lua_pushnil(L);
      }
      else {
          ereport(WARNING, (errmsg("tuple has no field '%s'", name)));
          lua_pushnil(L);
      }
      return 1;
  }
  //triggers data


  lua_push_oidstring(L, (int) t->relid);
  lua_rawget(L, LUA_REGISTRYINDEX);
  lua_getfield(L, -1, name);
  i = luaL_optinteger(L, -1, -1);


  if (i >= 0) {
      if (!t->null[i])
        luaP_pushdatum(L, t->value[i], t->tupdesc->attrs[i]->atttypid);
      else lua_pushnil(L);
  }
  else lua_pushnil(L);
  return 1;
}

static int luaP_tuplenewindex (lua_State *L) {
  luaP_Tuple *t = (luaP_Tuple *) lua_touserdata(L, 1);
  const char *name = luaL_checkstring(L, 2);
  int i;
  if (t->changed == -1) /* read-only? */
    return luaL_error(L, "tuple is read-only");
  lua_push_oidstring(L, (int) t->relid);
  lua_rawget(L, LUA_REGISTRYINDEX);
  lua_getfield(L, -1, name);
  i = luaL_optinteger(L, -1, -1);
  lua_settop(L, 3);
  if (i >= 0) { /* found? */
    bool isnull;
    t->value[i] = luaP_todatum(L, t->tupdesc->attrs[i]->atttypid,
        t->tupdesc->attrs[i]->atttypmod, &isnull, -1);
    t->null[i] = isnull;
    t->changed = 1;
  }
  else
    return luaL_error(L, "column not found in relation: '%s'", name);
  return 0;
}

static int luaP_tupletostring (lua_State *L) {
  lua_pushfstring(L, "%s: %p", PLLUA_TUPLEMT, lua_touserdata(L, 1));
  return 1;
}

void luaP_pushtuple_trg (lua_State *L, TupleDesc desc, HeapTuple tuple,
                     Oid relid, int readonly) {
    luaP_Tuple *t;
    int i, n;

    BEGINLUA;

    n = desc->natts;

    t = lua_newuserdata(L, sizeof(luaP_Tuple)
                        + n * (sizeof(Datum) + sizeof(bool)));
    if (readonly) {
        t->changed = -1;
    }
    else {
        t->changed = 0;
    }

    t->value = (Datum *) (t + 1);
    t->null = (bool *) (t->value + n);

    t->rtupdesc = 0;
    for (i = 0; i < n; i++) {
        bool isnull;
        t->value[i] = heap_getattr(tuple, desc->attrs[i]->attnum, desc,
                                   &isnull);
        t->null[i] = isnull;
    }

    t->tupdesc = desc;
    t->relid = relid;
    t->tuple = tuple;
    luaP_getfield(L, PLLUA_TUPLEMT);
    lua_setmetatable(L, -2);
    ENDLUAV(1);
}


/* adapted from SPI_modifytuple */
static HeapTuple luaP_copytuple (luaP_Tuple *t) {
  HeapTuple tuple = heap_form_tuple(t->tupdesc, t->value, t->null);
  /* copy identification info */
  tuple->t_data->t_ctid = t->tuple->t_data->t_ctid;
  tuple->t_self = t->tuple->t_self;
  tuple->t_tableOid = t->tuple->t_tableOid;
  if (t->tupdesc->tdhasoid)
    HeapTupleSetOid(tuple, HeapTupleGetOid(t->tuple));
  return SPI_copytuple(tuple); /* in upper mem context */
}

static luaP_Tuple *luaP_checktuple (lua_State *L, int pos) {
  luaP_Tuple *t = (luaP_Tuple *) lua_touserdata(L, pos);
  if (t != NULL) {
    if (lua_getmetatable(L, pos)) {
      luaP_getfield(L, PLLUA_TUPLEMT);
      if (!lua_rawequal(L, -1, -2)) /* not tuple? */
        t = NULL;
      lua_pop(L, 2); /* metatables */
    }
  }
  return t;
}

/* tuple on top of stack */
HeapTuple luaP_totuple (lua_State *L) {
  luaP_Tuple *t = luaP_checktuple(L, -1);
  if (t == NULL) return NULL; /* not a tuple */
  return (t->changed == 1) ? luaP_copytuple(t) : t->tuple;
}

/* tuple on top of stack */
HeapTuple luaP_casttuple (lua_State *L, TupleDesc tupdesc) {
  luaP_Tuple *t = luaP_checktuple(L, -1);
  int i;
  luaP_Buffer *b;
  if (t == NULL) return NULL; /* not a tuple */
  lua_push_oidstring(L, (int) t->relid);
  lua_rawget(L, LUA_REGISTRYINDEX); /* tuple desc table */
  b = luaP_getbuffer(L, tupdesc->natts);
  for (i = 0; i < tupdesc->natts; i++) {
    int j;
    lua_getfield(L, -1, NameStr(tupdesc->attrs[i]->attname));
    j = luaL_optinteger(L, -1, -1);
    if (j >= 0) {
      if (t->changed == -1) /* read-only? */
        b->value[i] = heap_getattr(t->tuple,
            t->tupdesc->attrs[j]->attnum, t->tupdesc, b->null + i);
      else {
        b->value[i] = t->value[j];
        b->null[i] = t->null[j];
      }
    }
    lua_pop(L, 1);
  }
  lua_pop(L, 1); /* desc table */
  return heap_form_tuple(tupdesc, b->value, b->null);
}

/* ======= TupleTable ======= */

static void luaP_pushtuptable (lua_State *L, Portal cursor) {
    luaP_Tuptable *t;

    BEGINLUA;

    luaP_getfield(L, PLLUA_TUPTABLE);
    t = (luaP_Tuptable *) lua_touserdata(L, -1);
    if (t == NULL) { /* not initialized? */
        lua_pop(L, 1);
        t = (luaP_Tuptable *) lua_newuserdata(L, sizeof(luaP_Tuptable));
        t->rtupdesc = 0;

        luaP_getfield(L, PLLUA_TUPTABLEMT);
        lua_setmetatable(L, -2);
        lua_pushlightuserdata(L, (void *) PLLUA_TUPTABLE);
        lua_pushvalue(L, -2); /* tuptable */
        lua_rawset(L, LUA_REGISTRYINDEX);
    }
    t->size = SPI_processed;
    t->tuptable = SPI_tuptable;
    t->rtupdesc = rtupdesc_ctor(L,SPI_tuptable->tupdesc);

    if (cursor == NULL || (cursor != NULL && t->cursor != cursor)) {
        t->cursor = cursor;
    }

    /* reset tuptable env */
    lua_newtable(L); /* env */
    lua_setuservalue(L, -2);
    ENDLUAV(1);
}

static int luaP_tuptableindex (lua_State *L) {
  luaP_Tuptable *t = (luaP_Tuptable *) lua_touserdata(L, 1);
  int k = lua_tointeger(L, 2);

  if (k == 0) { /* attributes? */

      lua_pushnil(L);
    }
  else if (k > 0 && k <= t->size) {
      lua_getuservalue(L, 1);
      lua_rawgeti(L, -1, k);
      if (lua_isnil(L, -1)) { /* not interned? */
          lua_pop(L, 1); /* nil */

          luaP_pushtuple_cmn(L, t->tuptable->vals[k - 1],
              1, t->rtupdesc);

          lua_pushvalue(L, -1);

          lua_rawseti(L, -3, k);
        }
    }else{
      lua_pushnil(L);
    }
  return 1;
}

static int luaP_tuptablelen (lua_State *L) {
  luaP_Tuptable *t = (luaP_Tuptable *) lua_touserdata(L, 1);
  lua_pushinteger(L, t->size);
  return 1;
}

static int luaP_tuptablegc (lua_State *L) {
  //in case SELECT * FROM get_rows('name'); not sure if collected...
  luaP_Tuptable *t = (luaP_Tuptable *) lua_touserdata(L, 1);
  rtupdesc_unref(t->rtupdesc);
  SPI_freetuptable(t->tuptable);
  return 0;
}

static int luaP_tuptabletostring (lua_State *L) {
  lua_pushfstring(L, "%s: %p", PLLUA_TUPTABLEMT, lua_touserdata(L, 1));
  return 1;
}


/* ======= Cursor ======= */

void luaP_pushcursor (lua_State *L, Portal cursor) {

  luaP_Cursor *c = (luaP_Cursor *) lua_newuserdata(L, sizeof(luaP_Cursor));
  c->cursor = cursor;
  c->rtupdesc = NULL;
  c->tupleQueue = NULL;
  c->resptr = register_resource(c, cursor_cleanup);
  luaP_getfield(L, PLLUA_CURSORMT);
  lua_setmetatable(L, -2);
}

Portal luaP_tocursor (lua_State *L, int pos) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, pos, PLLUA_CURSORMT);
  return c->cursor;
}

static int luaP_cursortostring (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) lua_touserdata(L, 1);
  lua_pushfstring(L, "%s: %p [%s]", PLLUA_CURSORMT, c, c->cursor->name);
  return 1;
}

static int luaP_cursorfetch (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, 1, PLLUA_CURSORMT);
#if LUA_VERSION_NUM >= 503
  SPI_cursor_fetch(c->cursor, 1, luaL_optinteger(L, 2, FETCH_ALL));
#else
  SPI_cursor_fetch(c->cursor, 1, luaL_optlong(L, 2, FETCH_ALL));
#endif
  if (SPI_processed > 0) /* any rows? */
    luaP_pushtuptable(L, c->cursor);
  else
    lua_pushnil(L);
  return 1;
}

static int luaP_cursormove (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, 1, PLLUA_CURSORMT);
#if LUA_VERSION_NUM >= 503
  SPI_cursor_move(c->cursor, 1, luaL_optinteger(L, 2, 0));
#else
  SPI_cursor_move(c->cursor, 1, luaL_optlong(L, 2, 0));
#endif
  return 0;
}

#if PG_VERSION_NUM >= 80300
static int luaP_cursorposfetch (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, 1, PLLUA_CURSORMT);
  FetchDirection fd = (lua_toboolean(L, 3)) ? FETCH_RELATIVE : FETCH_ABSOLUTE;
#if LUA_VERSION_NUM >= 503
  SPI_scroll_cursor_fetch(c->cursor, fd, luaL_optinteger(L, 2, FETCH_ALL));
#else
  SPI_scroll_cursor_fetch(c->cursor, fd, luaL_optlong(L, 2, FETCH_ALL));
#endif
  if (SPI_processed > 0) /* any rows? */
    luaP_pushtuptable(L, c->cursor);
  else
    lua_pushnil(L);
  return 1;
}

static int luaP_cursorposmove (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, 1, PLLUA_CURSORMT);
  FetchDirection fd = (lua_toboolean(L, 3)) ? FETCH_RELATIVE : FETCH_ABSOLUTE;
#if LUA_VERSION_NUM >= 503
  SPI_scroll_cursor_move(c->cursor, fd, luaL_optinteger(L, 2, 0));
#else
  SPI_scroll_cursor_move(c->cursor, fd, luaL_optlong(L, 2, 0));
#endif
  return 0;
}
#endif


static int luaP_cursorclose (lua_State *L) {
  luaP_Cursor *c = (luaP_Cursor *) luaP_checkudata(L, 1, PLLUA_CURSORMT);
  //c->resptr is null, cursor registered if used as upvalue
  c->resptr = unregister_resource(c->resptr);
  SPI_cursor_close(c->cursor);
  return 0;
}


/* ======= Plan ======= */

static int luaP_plangc (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) lua_touserdata(L, 1);
  if (p->issaved) SPI_freeplan(p->plan);
  return 0;
}

static int luaP_plantostring (lua_State *L) {
  lua_pushfstring(L, "plan: %p", lua_touserdata(L, 1));
  return 1;
}


static int luaP_executeplan (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) luaP_checkudata(L, 1, PLLUA_PLANMT);
  bool ro = (bool) lua_toboolean(L, 3);
#if LUA_VERSION_NUM >= 503
  long c = luaL_optinteger(L, 4, 0);
#else
  long c = luaL_optlong(L, 4, 0);
#endif
  int result = -1;
  Datum *values = NULL;
  char *nulls = NULL;


    if (p->nargs > 0) {
        luaP_Buffer *b;
        if (lua_type(L, 2) != LUA_TTABLE) luaP_typeerror(L, 2, "table");
        b = luaP_getbuffer(L, p->nargs);
        luaP_fillbuffer(L, 2, p->type, b);
        values = b->value;
        nulls = b->null;

    }

  PLLUA_PG_CATCH_RETHROW(
    result = SPI_execute_plan(p->plan, values, nulls, ro, c);
  );

  if (result < 0)
    return luaL_error(L, "SPI_execute_plan error: %d", result);
  if (((result == SPI_OK_SELECT)
       ||(result == SPI_OK_UPDATE_RETURNING)
       ||(result == SPI_OK_INSERT_RETURNING)
       ||(result == SPI_OK_DELETE_RETURNING)
       )&& SPI_processed > 0) /* any rows? */
    luaP_pushtuptable(L, NULL);
  else
    lua_pushnil(L);
  return 1;
}

static int luaP_saveplan (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) luaP_checkudata(L, 1, PLLUA_PLANMT);
  PLLUA_PG_CATCH_RETHROW(
    p->plan = SPI_saveplan(p->plan);
  );
  switch (SPI_result) {
    case SPI_ERROR_ARGUMENT:
      return luaL_error(L, "null plan to be saved");
    case SPI_ERROR_UNCONNECTED:
      return luaL_error(L, "unconnected procedure");
  }
  p->issaved = 1;
  return 1;
}

static int luaP_issavedplan (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) luaP_checkudata(L, 1, PLLUA_PLANMT);
  lua_pushboolean(L, p->issaved);
  return 1;
}

static int luaP_getcursorplan (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) luaP_checkudata(L, 1, PLLUA_PLANMT);
  bool ro = (bool) lua_toboolean(L, 3);
  const char *name = lua_tostring(L, 4);
  Portal cursor = NULL;
  Datum *values = NULL;
  char *nulls = NULL;
  if (SPI_is_cursor_plan(p->plan)) {
    if (p->nargs > 0) {
      luaP_Buffer *b;
      if (lua_type(L, 2) != LUA_TTABLE) luaP_typeerror(L, 2, "table");
      b = luaP_getbuffer(L, p->nargs);
      luaP_fillbuffer(L, 2, p->type, b);
      values = b->value;
      nulls = b->null;
    }
    PLLUA_PG_CATCH_RETHROW(
      cursor = SPI_cursor_open(name, p->plan, values, nulls, ro);
    );
    if (cursor == NULL)
      return luaL_error(L, "error opening cursor");
    luaP_pushcursor(L, cursor);
  }
  else lua_pushnil(L);
  return 1;
}

static int luaP_rowsplan (lua_State *L) {
  luaP_Plan *p = (luaP_Plan *) luaP_checkudata(L, 1, PLLUA_PLANMT);
  Portal cursor = NULL;
  Datum *values = NULL;
  char *nulls = NULL;
  if (!SPI_is_cursor_plan(p->plan))
    return luaL_error(L, "Plan is not iterable");
  if (p->nargs > 0) {
    luaP_Buffer *b;
    if (lua_type(L, 2) != LUA_TTABLE) luaP_typeerror(L, 2, "table");
    b = luaP_getbuffer(L, p->nargs);
    luaP_fillbuffer(L, 2, p->type, b);
    values = b->value;
    nulls = b->null;
  }
  PLLUA_PG_CATCH_RETHROW(
    cursor = SPI_cursor_open(NULL, p->plan, values, nulls, 1);
  );

  if (cursor == NULL)
    return luaL_error(L, "error opening cursor");
  luaP_pushcursor(L, cursor);
  lua_pushboolean(L, 0); /* not inited */
  lua_pushcclosure(L, luaP_rowsaux, 2);
  return 1;
}


/* ======= SPI ======= */
static int luaP_prepare (lua_State *L) {
    int nargs, cursoropt;
    const char *q = luaL_checkstring(L, 1);

    luaP_Plan *p;
    if (lua_isnoneornil(L, 2)) nargs = 0;
    else {
        if (lua_type(L, 2) != LUA_TTABLE) luaP_typeerror(L, 2, "table");
        nargs = lua_rawlen(L, 2);
    }
    cursoropt = luaL_optinteger(L, 3, 0);
    (void)cursoropt;
    p = (luaP_Plan *) lua_newuserdata(L,
                                      sizeof(luaP_Plan) + nargs * sizeof(Oid));
    p->issaved = 0;
    p->nargs = nargs;
    if (nargs > 0) { /* read types? */
        lua_pushnil(L);
        while (lua_next(L, 2)) {
            int k = lua_tointeger(L, -2);
            if (k > 0) {
                const char *s = luaL_checkstring(L, -1);
                Oid type = pg_to_regtype(s);
                if (type == InvalidOid)
                    return luaL_error(L, "invalid type to plan: %s", s);
                p->type[k - 1] = type;
            }
            lua_pop(L, 1);
        }
    }
    PLLUA_PG_CATCH_RETHROW(
        p->plan = SPI_prepare_cursor(q, nargs, p->type, cursoropt);
    );
    if (SPI_result < 0)
        return luaL_error(L, "SPI_prepare error: %d", SPI_result);
    luaP_getfield(L, PLLUA_PLANMT);
    lua_setmetatable(L, -2);
    return 1;
}

static int luaP_execute (lua_State *L) {
  int result = -1;
  PLLUA_PG_CATCH_RETHROW(
    result = SPI_execute(luaL_checkstring(L, 1),
                         (bool) lua_toboolean(L, 2),
#if LUA_VERSION_NUM >= 503
                         luaL_optinteger(L, 3, 0));
#else
                         luaL_optlong(L, 3, 0));
#endif
  );
  if (result < 0)
    return luaL_error(L, "SPI_execute_plan error: %d", result);
  if (result == SPI_OK_SELECT && SPI_processed > 0) /* any rows? */
    luaP_pushtuptable(L, NULL);
  else
    lua_pushnil(L);
  return 1;
}

/* returns cursor */
static int luaP_find (lua_State *L) {
  Portal cursor = SPI_cursor_find(luaL_checkstring(L, 1));
  if (cursor != NULL) luaP_pushcursor(L, cursor);
  else lua_pushnil(L);
  return 1;
}

static int luaP_rows (lua_State *L) {
  Portal cursor;
  PLLUA_PG_CATCH_RETHROW(
      SPI_plan *p = SPI_prepare_cursor(luaL_checkstring(L, 1), 0, NULL, 0);
      if (SPI_result < 0)
        return luaL_error(L, "SPI_prepare error: %d", SPI_result);
      if (!SPI_is_cursor_plan(p))
        return luaL_error(L, "Statement is not iterable");
      cursor = SPI_cursor_open(NULL, p, NULL, NULL, 1);
      SPI_freeplan(p);
      if (cursor == NULL)
        return luaL_error(L, "error opening cursor");
      luaP_pushcursor(L, cursor);
      lua_pushboolean(L, 0); /* not inited */
      lua_pushcclosure(L, luaP_rowsaux, 2);
  );
  return 1;
}


/* ======= luaP_registerspi ======= */

static const luaL_Reg luaP_Plan_funcs[] = {
  {"execute", luaP_executeplan},
  {"save", luaP_saveplan},
  {"issaved", luaP_issavedplan},
  {"getcursor", luaP_getcursorplan},
  {"rows", luaP_rowsplan},
  {NULL, NULL}
};

static const luaL_Reg luaP_Cursor_funcs[] = {
  {"fetch", luaP_cursorfetch},
  {"move", luaP_cursormove},
#if PG_VERSION_NUM >= 80300
  {"posfetch", luaP_cursorposfetch},
  {"posmove", luaP_cursorposmove},
#endif
  {"close", luaP_cursorclose},
  {NULL, NULL}
};

static const luaL_Reg luaP_SPI_funcs[] = {
  {"prepare", luaP_prepare},
  {"execute", luaP_execute},
  {"find", luaP_find},
  {"rows", luaP_rows},
  {NULL, NULL}
};

static const luaL_Reg luaP_Tuple_mt[] = {
  {"__index", luaP_tupleindex},
  {"__newindex", luaP_tuplenewindex},
  {"__tostring", luaP_tupletostring},
  {"__gc", luaP_tuplegc},
  {NULL, NULL}
};

static const luaL_Reg luaP_p_Tuple_mt[] = {
  {"__index", luaP_p_tupleindex},
  //{"__newindex", luaP_tuplenewindex},
  //{"__tostring", luaP_tupletostring},
  {"__gc", luaP_p_tuplegc},
  {NULL, NULL}
};

static const luaL_Reg luaP_Tuptable_mt[] = {
  {"__index", luaP_tuptableindex},
  {"__len", luaP_tuptablelen},
  {"__tostring", luaP_tuptabletostring},
  {"__gc", luaP_tuptablegc},
  {NULL, NULL}
};

static const luaL_Reg luaP_Cursor_mt[] = {
  {"__tostring", luaP_cursortostring},
  {"__gc", luaP_cursorgc},
  {NULL, NULL}
};

static const luaL_Reg luaP_Plan_mt[] = {
  {"__gc", luaP_plangc},
  {"__tostring", luaP_plantostring},
  {NULL, NULL}
};

void luaP_registerspi (lua_State *L) {
  /* tuple */
  luaP_newmetatable(L, PLLUA_TUPLEMT);
  luaP_register(L, luaP_Tuple_mt);
  lua_pop(L, 1);
  /* ptuple */
  luaP_newmetatable(L, PLLUA_P_TUPLEMT);
  luaP_register(L, luaP_p_Tuple_mt);
  lua_pop(L, 1);
  /* tuptable */
  luaP_newmetatable(L, PLLUA_TUPTABLEMT);
  luaP_register(L, luaP_Tuptable_mt);
  lua_pop(L, 1);
  /* cursor */
  luaP_newmetatable(L, PLLUA_CURSORMT);
  lua_newtable(L);
  luaP_register(L, luaP_Cursor_funcs);
  lua_setfield(L, -2, "__index");
  luaP_register(L, luaP_Cursor_mt);
  lua_pop(L, 1);
  /* plan */
  luaP_newmetatable(L, PLLUA_PLANMT);
  lua_newtable(L);
  luaP_register(L, luaP_Plan_funcs);
  lua_setfield(L, -2, "__index");
  luaP_register(L, luaP_Plan_mt);
  lua_pop(L, 1);
  /* SPI */
  lua_newtable(L);
#if PG_VERSION_NUM >= 80300
  lua_newtable(L); /* cursor options */
  lua_pushinteger(L, CURSOR_OPT_BINARY);
  lua_setfield(L, -2, "binary");
  lua_pushinteger(L, CURSOR_OPT_SCROLL);
  lua_setfield(L, -2, "scroll");
  lua_pushinteger(L, CURSOR_OPT_NO_SCROLL);
  lua_setfield(L, -2, "noscroll");
  lua_pushinteger(L, CURSOR_OPT_INSENSITIVE);
  lua_setfield(L, -2, "insensitive");
  lua_pushinteger(L, CURSOR_OPT_HOLD); /* ignored */
  lua_setfield(L, -2, "hold");
  lua_pushinteger(L, CURSOR_OPT_FAST_PLAN);
  lua_setfield(L, -2, "fastplan");
  lua_setfield(L, -2, "option");
#endif
  luaP_register(L, luaP_SPI_funcs);
}