/* connection_type.c - python interface to connection objects
 *
 * Copyright (C) 2003-2010 Federico Di Gregorio <fog@debian.org>
 *
 * This file is part of psycopg.
 *
 * psycopg2 is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link this program with the OpenSSL library (or with
 * modified versions of OpenSSL that use the same license as OpenSSL),
 * and distribute linked combinations including the two.
 *
 * You must obey the GNU Lesser General Public License in all respects for
 * all of the code used other than OpenSSL.
 *
 * psycopg2 is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 */

#define PSYCOPG_MODULE
#include "psycopg/psycopg.h"

#include "psycopg/connection.h"
#include "psycopg/cursor.h"
#include "psycopg/pqpath.h"
#include "psycopg/lobject.h"
#include "psycopg/green.h"
#include "psycopg/xid.h"

#include <string.h>
#include <ctype.h>


/** DBAPI methods **/

/* cursor method - allocate a new cursor */

#define psyco_conn_cursor_doc \
"cursor(cursor_factory=extensions.cursor) -- new cursor\n\n"                \
"Return a new cursor.\n\nThe ``cursor_factory`` argument can be used to\n"  \
"create non-standard cursors by passing a class different from the\n"       \
"default. Note that the new class *should* be a sub-class of\n"             \
"`extensions.cursor`.\n\n"                                                  \
":rtype: `extensions.cursor`"

static PyObject *
psyco_conn_cursor(connectionObject *self, PyObject *args, PyObject *keywds)
{
    const char *name = NULL;
    PyObject *obj, *factory = NULL;

    static char *kwlist[] = {"name", "cursor_factory", NULL};

    if (!PyArg_ParseTupleAndKeywords(args, keywds, "|sO", kwlist,
                                     &name, &factory)) {
        return NULL;
    }

    EXC_IF_CONN_CLOSED(self);

    if (self->status != CONN_STATUS_READY &&
        self->status != CONN_STATUS_BEGIN &&
        self->status != CONN_STATUS_PREPARED) {
        PyErr_SetString(OperationalError,
                        "asynchronous connection attempt underway");
        return NULL;
    }

    if (name != NULL && self->async == 1) {
        PyErr_SetString(ProgrammingError,
                        "asynchronous connections "
                        "cannot produce named cursors");
        return NULL;
    }

    Dprintf("psyco_conn_cursor: new cursor for connection at %p", self);
    Dprintf("psyco_conn_cursor:     parameters: name = %s", name);

    if (factory == NULL) factory = (PyObject *)&cursorType;
    if (name)
        obj = PyObject_CallFunction(factory, "Os", self, name);
    else
        obj = PyObject_CallFunctionObjArgs(factory, self, NULL);

    if (obj == NULL) return NULL;
    if (PyObject_IsInstance(obj, (PyObject *)&cursorType) == 0) {
        PyErr_SetString(PyExc_TypeError,
            "cursor factory must be subclass of psycopg2._psycopg.cursor");
        Py_DECREF(obj);
        return NULL;
    }

    Dprintf("psyco_conn_cursor: new cursor at %p: refcnt = "
        FORMAT_CODE_PY_SSIZE_T,
        obj, Py_REFCNT(obj)
      );
    return obj;
}


/* close method - close the connection and all related cursors */

#define psyco_conn_close_doc "close() -- Close the connection."

static PyObject *
psyco_conn_close(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);

    Dprintf("psyco_conn_close: closing connection at %p", self);
    conn_close(self);
    Dprintf("psyco_conn_close: connection at %p closed", self);

    Py_INCREF(Py_None);
    return Py_None;
}


/* commit method - commit all changes to the database */

#define psyco_conn_commit_doc "commit() -- Commit all changes to database."

static PyObject *
psyco_conn_commit(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, commit);
    EXC_IF_TPC_BEGIN(self, commit);

    if (conn_commit(self) < 0)
        return NULL;

    Py_INCREF(Py_None);
    return Py_None;
}


/* rollback method - roll back all changes done to the database */

#define psyco_conn_rollback_doc \
"rollback() -- Roll back all changes done to database."

static PyObject *
psyco_conn_rollback(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, rollback);
    EXC_IF_TPC_BEGIN(self, rollback);

    if (conn_rollback(self) < 0)
        return NULL;

    Py_INCREF(Py_None);
    return Py_None;
}


#define psyco_conn_xid_doc \
"xid(format_id, gtrid, bqual) -- create a transaction identifier."

static PyObject *
psyco_conn_xid(connectionObject *self, PyObject *args, PyObject *kwargs)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_TPC_NOT_SUPPORTED(self);

    return PyObject_Call((PyObject *)&XidType, args, kwargs);
}


#define psyco_conn_tpc_begin_doc \
"tpc_begin(xid) -- begin a TPC transaction with given transaction ID xid."

static PyObject *
psyco_conn_tpc_begin(connectionObject *self, PyObject *args)
{
    PyObject *rv = NULL;
    XidObject *xid = NULL;
    PyObject *oxid;

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, tpc_begin);
    EXC_IF_TPC_NOT_SUPPORTED(self);
    EXC_IF_IN_TRANSACTION(self, tpc_begin);

    if (!PyArg_ParseTuple(args, "O", &oxid)) {
        goto exit;
    }

    if (NULL == (xid = xid_ensure(oxid))) {
        goto exit;
    }

    /* two phase commit and autocommit make no point */
    if (self->autocommit) {
        PyErr_SetString(ProgrammingError,
            "tpc_begin can't be called in autocommit mode");
        goto exit;
    }

    if (conn_tpc_begin(self, xid) < 0) {
        goto exit;
    }

    Py_INCREF(Py_None);
    rv = Py_None;

exit:
    Py_XDECREF(xid);
    return rv;
}


#define psyco_conn_tpc_prepare_doc \
"tpc_prepare() -- perform the first phase of a two-phase transaction."

static PyObject *
psyco_conn_tpc_prepare(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, tpc_prepare);
    EXC_IF_TPC_PREPARED(self, tpc_prepare);

    if (NULL == self->tpc_xid) {
        PyErr_SetString(ProgrammingError,
            "prepare must be called inside a two-phase transaction");
        return NULL;
    }

    if (0 > conn_tpc_command(self, "PREPARE TRANSACTION", self->tpc_xid)) {
        return NULL;
    }

    /* transaction prepared: set the state so that no operation
     * can be performed until commit. */
    self->status = CONN_STATUS_PREPARED;

    Py_INCREF(Py_None);
    return Py_None;
}


/* the type of conn_commit/conn_rollback */
typedef int (*_finish_f)(connectionObject *self);

/* Implement tpc_commit/tpc_rollback.
 *
 * This is a common framework performing the chechs and state manipulation
 * common to the two functions.
 *
 * Parameters are:
 * - self, args: passed by Python
 * - opc_f: the function to call in case of one-phase commit/rollback
 *          one of conn_commit/conn_rollback
 * - tpc_cmd: the command to execute for a two-phase commit/rollback
 *
 * The function can be called in three cases:
 * - If xid is specified, the status must be "ready";
 *   issue the commit/rollback prepared.
 * - if xid is not specified and status is "begin" with a xid,
 *   issue a normal commit/rollback.
 * - if xid is not specified and status is "prepared",
 *   issue the commit/rollback prepared.
 */
static PyObject *
_psyco_conn_tpc_finish(connectionObject *self, PyObject *args,
    _finish_f opc_f, char *tpc_cmd)
{
    PyObject *oxid = NULL;
    XidObject *xid = NULL;
    PyObject *rv = NULL;

    if (!PyArg_ParseTuple(args, "|O", &oxid)) { goto exit; }

    if (oxid) {
        if (!(xid = xid_ensure(oxid))) { goto exit; }
    }

    if (xid) {
        /* committing/aborting a recovered transaction. */
        if (self->status != CONN_STATUS_READY) {
            PyErr_SetString(ProgrammingError,
                "tpc_commit/tpc_rollback with a xid "
                "must be called outside a transaction");
            goto exit;
        }
        if (0 > conn_tpc_command(self, tpc_cmd, xid)) {
            goto exit;
        }
    } else {
        /* committing/aborting our own transaction. */
        if (!self->tpc_xid) {
            PyErr_SetString(ProgrammingError,
                "tpc_commit/tpc_rollback with no parameter "
                "must be called in a two-phase transaction");
            goto exit;
        }

        switch (self->status) {
          case CONN_STATUS_BEGIN:
            if (0 > opc_f(self)) { goto exit; }
            break;

          case CONN_STATUS_PREPARED:
            if (0 > conn_tpc_command(self, tpc_cmd, self->tpc_xid)) {
                goto exit;
            }
            break;

          default:
            PyErr_SetString(InterfaceError,
                "unexpected state in tpc_commit/tpc_rollback");
            goto exit;
        }

        Py_CLEAR(self->tpc_xid);

        /* connection goes ready */
        self->status = CONN_STATUS_READY;
    }

    Py_INCREF(Py_None);
    rv = Py_None;

exit:
    Py_XDECREF(xid);
    return rv;
}

#define psyco_conn_tpc_commit_doc \
"tpc_commit([xid]) -- commit a transaction previously prepared."

static PyObject *
psyco_conn_tpc_commit(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, tpc_commit);
    EXC_IF_TPC_NOT_SUPPORTED(self);

    return _psyco_conn_tpc_finish(self, args,
                                  conn_commit, "COMMIT PREPARED");
}

#define psyco_conn_tpc_rollback_doc \
"tpc_rollback([xid]) -- abort a transaction previously prepared."

static PyObject *
psyco_conn_tpc_rollback(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, tpc_rollback);
    EXC_IF_TPC_NOT_SUPPORTED(self);

    return _psyco_conn_tpc_finish(self, args,
                                  conn_rollback, "ROLLBACK PREPARED");
}

#define psyco_conn_tpc_recover_doc \
"tpc_recover() -- returns a list of pending transaction IDs."

static PyObject *
psyco_conn_tpc_recover(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, tpc_recover);
    EXC_IF_TPC_PREPARED(self, tpc_recover);
    EXC_IF_TPC_NOT_SUPPORTED(self);

    return conn_tpc_recover(self);
}


#ifdef PSYCOPG_EXTENSIONS


/* parse a python object into one of the possible isolation level values */

extern const IsolationLevel conn_isolevels[];

static const char *
_psyco_conn_parse_isolevel(connectionObject *self, PyObject *pyval)
{
    const IsolationLevel *isolevel = NULL;

    Py_INCREF(pyval);   /* for ensure_bytes */

    /* parse from one of the level constants */
    if (PyInt_Check(pyval)) {
        long level = PyInt_AsLong(pyval);
        if (level == -1 && PyErr_Occurred()) { goto exit; }
        if (level < 1 || level > 4) {
            PyErr_SetString(PyExc_ValueError,
                "isolation_level must be between 1 and 4");
            goto exit;
        }

        isolevel = conn_isolevels + level;
    }

    /* parse from the string -- this includes "default" */
    else {
        isolevel = conn_isolevels;
        while ((++isolevel)->name) {
            if (!(pyval = psycopg_ensure_bytes(pyval))) {
                goto exit;
            }
            if (0 == strcasecmp(isolevel->name, Bytes_AS_STRING(pyval))) {
                break;
            }
        }
        if (!isolevel->name) {
            char msg[256];
            snprintf(msg, sizeof(msg),
                "bad value for isolation_level: '%s'", Bytes_AS_STRING(pyval));
            PyErr_SetString(PyExc_ValueError, msg);
        }
    }

    /* use only supported levels on older PG versions */
    if (isolevel && self->server_version < 80000) {
        if (isolevel->value == 1 || isolevel->value == 3) {
            ++isolevel;
        }
    }

exit:
    Py_XDECREF(pyval);

    return isolevel ? isolevel->name : NULL;
}

/* convert True/False/"default" into a C string */

static const char *
_psyco_conn_parse_onoff(PyObject *pyval)
{
    int istrue = PyObject_IsTrue(pyval);
    if (-1 == istrue) { return NULL; }
    if (istrue) {
        int cmp;
        PyObject *pydef;
        if (!(pydef = Text_FromUTF8("default"))) { return NULL; }
        cmp = PyObject_RichCompareBool(pyval, pydef, Py_EQ);
        Py_DECREF(pydef);
        if (-1 == cmp) { return NULL; }
        return cmp ? "default" : "on";
    }
    else {
        return "off";
    }
}

/* set_session - set default transaction characteristics */

#define psyco_conn_set_session_doc \
"set_session(...) -- Set one or more parameters for the next transactions.\n\n" \
"Accepted arguments are 'isolation_level', 'readonly', 'deferrable', 'autocommit'."

static PyObject *
psyco_conn_set_session(connectionObject *self, PyObject *args, PyObject *kwargs)
{
    PyObject *isolevel = Py_None;
    PyObject *readonly = Py_None;
    PyObject *deferrable = Py_None;
    PyObject *autocommit = Py_None;

    const char *c_isolevel = NULL;
    const char *c_readonly = NULL;
    const char *c_deferrable = NULL;
    int c_autocommit = self->autocommit;

    static char *kwlist[] =
        {"isolation_level", "readonly", "deferrable", "autocommit", NULL};

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, set_session);
    EXC_IF_IN_TRANSACTION(self, set_session);

    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|OOOO", kwlist,
            &isolevel, &readonly, &deferrable, &autocommit)) {
        return NULL;
    }

    if (Py_None != isolevel) {
        if (!(c_isolevel = _psyco_conn_parse_isolevel(self, isolevel))) {
            return NULL;
        }
    }

    if (Py_None != readonly) {
        if (!(c_readonly = _psyco_conn_parse_onoff(readonly))) {
            return NULL;
        }
    }
    if (Py_None != deferrable) {
        if (self->server_version < 90100) {
            PyErr_SetString(ProgrammingError,
                "the 'deferrable' setting is only available"
                " from PostgreSQL 9.1");
            return NULL;
        }
        if (!(c_deferrable = _psyco_conn_parse_onoff(deferrable))) {
            return NULL;
        }
    }
    if (Py_None != autocommit) {
        c_autocommit = PyObject_IsTrue(autocommit);
        if (-1 == c_autocommit) { return NULL; }
    }

    if (0 != conn_set_session(self,
            c_isolevel, c_readonly, c_deferrable, c_autocommit)) {
        return NULL;
    }

    Py_INCREF(Py_None);
    return Py_None;
}


#define psyco_conn_autocommit_doc \
"set or return the autocommit status."

static PyObject *
psyco_conn_autocommit_get(connectionObject *self)
{
    PyObject *ret;
    ret = self->autocommit ? Py_True : Py_False;
    Py_INCREF(ret);
    return ret;
}

static PyObject *
_psyco_conn_autocommit_set_checks(connectionObject *self)
{
    /* wrapper to use the EXC_IF macros.
     * return NULL in case of error, else whatever */
    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, autocommit);
    EXC_IF_IN_TRANSACTION(self, autocommit);
    return Py_None;     /* borrowed */
}

static int
psyco_conn_autocommit_set(connectionObject *self, PyObject *pyvalue)
{
    int value;

    if (!_psyco_conn_autocommit_set_checks(self)) { return -1; }
    if (-1 == (value = PyObject_IsTrue(pyvalue))) { return -1; }
    if (0 != conn_set_autocommit(self, value)) { return -1; }

    return 0;
}


/* isolation_level - return the current isolation level */

static PyObject *
psyco_conn_isolation_level_get(connectionObject *self)
{
    int rv = conn_get_isolation_level(self);
    if (-1 == rv) { return NULL; }
    return PyInt_FromLong((long)rv);
}


/* set_isolation_level method - switch connection isolation level */

#define psyco_conn_set_isolation_level_doc \
"set_isolation_level(level) -- Switch isolation level to ``level``."

static PyObject *
psyco_conn_set_isolation_level(connectionObject *self, PyObject *args)
{
    int level = 1;

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, set_isolation_level);
    EXC_IF_TPC_PREPARED(self, set_isolation_level);

    if (!PyArg_ParseTuple(args, "i", &level)) return NULL;

    if (level < 0 || level > 4) {
        PyErr_SetString(PyExc_ValueError,
            "isolation level must be between 0 and 4");
        return NULL;
    }

    if (conn_switch_isolation_level(self, level) < 0) {
        return NULL;
    }

    Py_INCREF(Py_None);
    return Py_None;
}

/* set_client_encoding method - set client encoding */

#define psyco_conn_set_client_encoding_doc \
"set_client_encoding(encoding) -- Set client encoding to ``encoding``."

static PyObject *
psyco_conn_set_client_encoding(connectionObject *self, PyObject *args)
{
    const char *enc;
    PyObject *rv = NULL;

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, set_client_encoding);
    EXC_IF_TPC_PREPARED(self, set_client_encoding);

    if (!PyArg_ParseTuple(args, "s", &enc)) return NULL;

    if (conn_set_client_encoding(self, enc) == 0) {
        Py_INCREF(Py_None);
        rv = Py_None;
    }
    return rv;
}

/* get_transaction_status method - Get backend transaction status */

#define psyco_conn_get_transaction_status_doc \
"get_transaction_status() -- Get backend transaction status."

static PyObject *
psyco_conn_get_transaction_status(connectionObject *self, PyObject *args)
{
    EXC_IF_CONN_CLOSED(self);

    return PyInt_FromLong((long)PQtransactionStatus(self->pgconn));
}

/* get_parameter_status method - Get server parameter status */

#define psyco_conn_get_parameter_status_doc \
"get_parameter_status(parameter) -- Get backend parameter status.\n\n" \
"Potential values for ``parameter``:\n" \
"  server_version, server_encoding, client_encoding, is_superuser,\n" \
"  session_authorization, DateStyle, TimeZone, integer_datetimes,\n" \
"  and standard_conforming_strings\n" \
"If server did not report requested parameter, None is returned.\n\n" \
"See libpq docs for PQparameterStatus() for further details."

static PyObject *
psyco_conn_get_parameter_status(connectionObject *self, PyObject *args)
{
    const char *param = NULL;
    const char *val = NULL;

    EXC_IF_CONN_CLOSED(self);

    if (!PyArg_ParseTuple(args, "s", &param)) return NULL;

    val = PQparameterStatus(self->pgconn, param);
    if (!val) {
        Py_INCREF(Py_None);
        return Py_None;
    }
    return conn_text_from_chars(self, val);
}


/* lobject method - allocate a new lobject */

#define psyco_conn_lobject_doc \
"lobject(oid=0, mode=0, new_oid=0, new_file=None,\n"                        \
"       lobject_factory=extensions.lobject) -- new lobject\n\n"             \
"Return a new lobject.\n\nThe ``lobject_factory`` argument can be used\n"   \
"to create non-standard lobjects by passing a class different from the\n"   \
"default. Note that the new class *should* be a sub-class of\n"             \
"`extensions.lobject`.\n\n"                                                 \
":rtype: `extensions.lobject`"

static PyObject *
psyco_conn_lobject(connectionObject *self, PyObject *args, PyObject *keywds)
{
    Oid oid=InvalidOid, new_oid=InvalidOid;
    char *new_file = NULL;
    const char *smode = "";
    PyObject *factory = (PyObject *)&lobjectType;
    PyObject *obj;

    static char *kwlist[] = {"oid", "mode", "new_oid", "new_file",
                             "cursor_factory", NULL};

    if (!PyArg_ParseTupleAndKeywords(args, keywds, "|izizO", kwlist,
                                     &oid, &smode, &new_oid, &new_file,
                                     &factory)) {
        return NULL;
    }

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, lobject);
    EXC_IF_GREEN(lobject);
    EXC_IF_TPC_PREPARED(self, lobject);

    Dprintf("psyco_conn_lobject: new lobject for connection at %p", self);
    Dprintf("psyco_conn_lobject:     parameters: oid = %d, mode = %s",
            oid, smode);
    Dprintf("psyco_conn_lobject:     parameters: new_oid = %d, new_file = %s",
            new_oid, new_file);

    if (new_file)
        obj = PyObject_CallFunction(factory, "Oisis",
            self, oid, smode, new_oid, new_file);
    else
        obj = PyObject_CallFunction(factory, "Oisi",
            self, oid, smode, new_oid);

    if (obj == NULL) return NULL;
    if (PyObject_IsInstance(obj, (PyObject *)&lobjectType) == 0) {
        PyErr_SetString(PyExc_TypeError,
            "lobject factory must be subclass of psycopg2._psycopg.lobject");
        Py_DECREF(obj);
        return NULL;
    }

    Dprintf("psyco_conn_lobject: new lobject at %p: refcnt = "
            FORMAT_CODE_PY_SSIZE_T,
            obj, Py_REFCNT(obj));
    return obj;
}

/* get the current backend pid */

#define psyco_conn_get_backend_pid_doc \
"get_backend_pid() -- Get backend process id."

static PyObject *
psyco_conn_get_backend_pid(connectionObject *self)
{
    EXC_IF_CONN_CLOSED(self);

    return PyInt_FromLong((long)PQbackendPID(self->pgconn));
}

/* reset the currect connection */

#define psyco_conn_reset_doc \
"reset() -- Reset current connection to defaults."

static PyObject *
psyco_conn_reset(connectionObject *self)
{
    int res;

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_CONN_ASYNC(self, reset);

    if (pq_reset(self) < 0)
        return NULL;

    res = conn_setup(self, self->pgconn);
    if (res < 0)
        return NULL;

    Py_INCREF(Py_None);
    return Py_None;
}

static PyObject *
psyco_conn_get_exception(PyObject *self, void *closure)
{
    PyObject *exception = *(PyObject **)closure;

    Py_INCREF(exception);
    return exception;
}

static PyObject *
psyco_conn_poll(connectionObject *self)
{
    int res;

    EXC_IF_CONN_CLOSED(self);

    res = conn_poll(self);
    if (res != PSYCO_POLL_ERROR || !PyErr_Occurred()) {
        return PyInt_FromLong(res);
    } else {
        /* There is an error and an exception is already in place */
        return NULL;
    }
}


/* extension: fileno - return the file descriptor of the connection */

#define psyco_conn_fileno_doc \
"fileno() -> int -- Return file descriptor associated to database connection."

static PyObject *
psyco_conn_fileno(connectionObject *self)
{
    long int socket;

    EXC_IF_CONN_CLOSED(self);

    socket = (long int)PQsocket(self->pgconn);

    return PyInt_FromLong(socket);
}


/* extension: isexecuting - check for asynchronous operations */

#define psyco_conn_isexecuting_doc                           \
"isexecuting() -> bool -- Return True if the connection is " \
 "executing an asynchronous operation."

static PyObject *
psyco_conn_isexecuting(connectionObject *self)
{
    /* synchronous connections will always return False */
    if (self->async == 0) {
        Py_INCREF(Py_False);
        return Py_False;
    }

    /* check if the connection is still being built */
    if (self->status != CONN_STATUS_READY) {
        Py_INCREF(Py_True);
        return Py_True;
    }

    /* check if there is a query being executed */
    if (self->async_cursor != NULL) {
        Py_INCREF(Py_True);
        return Py_True;
    }

    /* otherwise it's not executing */
    Py_INCREF(Py_False);
    return Py_False;
}


/* extension: cancel - cancel the current operation */

#define psyco_conn_cancel_doc                           \
"cancel() -- cancel the current operation"

static PyObject *
psyco_conn_cancel(connectionObject *self)
{
    char errbuf[256];

    EXC_IF_CONN_CLOSED(self);
    EXC_IF_TPC_PREPARED(self, cancel);

    /* do not allow cancellation while the connection is being built */
    Dprintf("psyco_conn_cancel: cancelling with key %p", self->cancel);
    if (self->status != CONN_STATUS_READY &&
        self->status != CONN_STATUS_BEGIN) {
        PyErr_SetString(OperationalError,
                        "asynchronous connection attempt underway");
        return NULL;
    }

    if (PQcancel(self->cancel, errbuf, sizeof(errbuf)) == 0) {
        Dprintf("psyco_conn_cancel: cancelling failed: %s", errbuf);
        PyErr_SetString(OperationalError, errbuf);
        return NULL;
    }
    Py_INCREF(Py_None);
    return Py_None;
}

#endif  /* PSYCOPG_EXTENSIONS */


/** the connection object **/


/* object method list */

static struct PyMethodDef connectionObject_methods[] = {
    {"cursor", (PyCFunction)psyco_conn_cursor,
     METH_VARARGS|METH_KEYWORDS, psyco_conn_cursor_doc},
    {"close", (PyCFunction)psyco_conn_close,
     METH_NOARGS, psyco_conn_close_doc},
    {"commit", (PyCFunction)psyco_conn_commit,
     METH_NOARGS, psyco_conn_commit_doc},
    {"rollback", (PyCFunction)psyco_conn_rollback,
     METH_NOARGS, psyco_conn_rollback_doc},
    {"xid", (PyCFunction)psyco_conn_xid,
     METH_VARARGS|METH_KEYWORDS, psyco_conn_xid_doc},
    {"tpc_begin", (PyCFunction)psyco_conn_tpc_begin,
     METH_VARARGS, psyco_conn_tpc_begin_doc},
    {"tpc_prepare", (PyCFunction)psyco_conn_tpc_prepare,
     METH_NOARGS, psyco_conn_tpc_prepare_doc},
    {"tpc_commit", (PyCFunction)psyco_conn_tpc_commit,
     METH_VARARGS, psyco_conn_tpc_commit_doc},
    {"tpc_rollback", (PyCFunction)psyco_conn_tpc_rollback,
     METH_VARARGS, psyco_conn_tpc_rollback_doc},
    {"tpc_recover", (PyCFunction)psyco_conn_tpc_recover,
     METH_NOARGS, psyco_conn_tpc_recover_doc},
#ifdef PSYCOPG_EXTENSIONS
    {"set_session", (PyCFunction)psyco_conn_set_session,
     METH_VARARGS|METH_KEYWORDS, psyco_conn_set_session_doc},
    {"set_isolation_level", (PyCFunction)psyco_conn_set_isolation_level,
     METH_VARARGS, psyco_conn_set_isolation_level_doc},
    {"set_client_encoding", (PyCFunction)psyco_conn_set_client_encoding,
     METH_VARARGS, psyco_conn_set_client_encoding_doc},
    {"get_transaction_status", (PyCFunction)psyco_conn_get_transaction_status,
     METH_NOARGS, psyco_conn_get_transaction_status_doc},
    {"get_parameter_status", (PyCFunction)psyco_conn_get_parameter_status,
     METH_VARARGS, psyco_conn_get_parameter_status_doc},
    {"get_backend_pid", (PyCFunction)psyco_conn_get_backend_pid,
     METH_NOARGS, psyco_conn_get_backend_pid_doc},
    {"lobject", (PyCFunction)psyco_conn_lobject,
     METH_VARARGS|METH_KEYWORDS, psyco_conn_lobject_doc},
    {"reset", (PyCFunction)psyco_conn_reset,
     METH_NOARGS, psyco_conn_reset_doc},
    {"poll", (PyCFunction)psyco_conn_poll,
     METH_NOARGS, psyco_conn_lobject_doc},
    {"fileno", (PyCFunction)psyco_conn_fileno,
     METH_NOARGS, psyco_conn_fileno_doc},
    {"isexecuting", (PyCFunction)psyco_conn_isexecuting,
     METH_NOARGS, psyco_conn_isexecuting_doc},
    {"cancel", (PyCFunction)psyco_conn_cancel,
     METH_NOARGS, psyco_conn_cancel_doc},
#endif
    {NULL}
};

/* object member list */

static struct PyMemberDef connectionObject_members[] = {
#ifdef PSYCOPG_EXTENSIONS
    {"closed", T_LONG, offsetof(connectionObject, closed), READONLY,
        "True if the connection is closed."},
    {"encoding", T_STRING, offsetof(connectionObject, encoding), READONLY,
        "The current client encoding."},
    {"notices", T_OBJECT, offsetof(connectionObject, notice_list), READONLY},
    {"notifies", T_OBJECT, offsetof(connectionObject, notifies), READONLY},
    {"dsn", T_STRING, offsetof(connectionObject, dsn), READONLY,
        "The current connection string."},
    {"async", T_LONG, offsetof(connectionObject, async), READONLY,
        "True if the connection is asynchronous."},
    {"status", T_INT,
        offsetof(connectionObject, status), READONLY,
        "The current transaction status."},
    {"string_types", T_OBJECT, offsetof(connectionObject, string_types), READONLY,
        "A set of typecasters to convert textual values."},
    {"binary_types", T_OBJECT, offsetof(connectionObject, binary_types), READONLY,
        "A set of typecasters to convert binary values."},
    {"protocol_version", T_INT,
        offsetof(connectionObject, protocol), READONLY,
        "Protocol version used for this connection. Currently always 3."},
    {"server_version", T_INT,
        offsetof(connectionObject, server_version), READONLY,
        "Server version."},
#endif
    {NULL}
};

#define EXCEPTION_GETTER(exc) \
    { #exc, psyco_conn_get_exception, NULL, exc ## _doc, &exc }

static struct PyGetSetDef connectionObject_getsets[] = {
    /* DBAPI-2.0 extensions (exception objects) */
    EXCEPTION_GETTER(Error),
    EXCEPTION_GETTER(Warning),
    EXCEPTION_GETTER(InterfaceError),
    EXCEPTION_GETTER(DatabaseError),
    EXCEPTION_GETTER(InternalError),
    EXCEPTION_GETTER(OperationalError),
    EXCEPTION_GETTER(ProgrammingError),
    EXCEPTION_GETTER(IntegrityError),
    EXCEPTION_GETTER(DataError),
    EXCEPTION_GETTER(NotSupportedError),
#ifdef PSYCOPG_EXTENSIONS
    { "autocommit",
        (getter)psyco_conn_autocommit_get,
        (setter)psyco_conn_autocommit_set,
        psyco_conn_autocommit_doc },
    { "isolation_level",
        (getter)psyco_conn_isolation_level_get,
        (setter)NULL,
        "The current isolation level." },
#endif
    {NULL}
};
#undef EXCEPTION_GETTER

/* initialization and finalization methods */

static int
connection_setup(connectionObject *self, const char *dsn, long int async)
{
    char *pos;
    int res = -1;

    Dprintf("connection_setup: init connection object at %p, "
	    "async %ld, refcnt = " FORMAT_CODE_PY_SSIZE_T,
            self, async, Py_REFCNT(self)
      );

    if (!(self->dsn = strdup(dsn))) {
        PyErr_NoMemory();
        goto exit;
    }
    if (!(self->notice_list = PyList_New(0))) { goto exit; }
    if (!(self->notifies = PyList_New(0))) { goto exit; }
    self->async = async;
    self->status = CONN_STATUS_SETUP;
    self->async_status = ASYNC_DONE;
    if (!(self->string_types = PyDict_New())) { goto exit; }
    if (!(self->binary_types = PyDict_New())) { goto exit; }
    /* other fields have been zeroed by tp_alloc */

    pthread_mutex_init(&(self->lock), NULL);

    if (conn_connect(self, async) != 0) {
        Dprintf("connection_init: FAILED");
        goto exit;
    }
    else {
        Dprintf("connection_setup: good connection object at %p, refcnt = "
            FORMAT_CODE_PY_SSIZE_T,
            self, Py_REFCNT(self)
          );
        res = 0;
    }

    /* here we obfuscate the password even if there was a connection error */
    pos = strstr(self->dsn, "password");
    if (pos != NULL) {
        for (pos = pos+9 ; *pos != '\0' && *pos != ' '; pos++)
            *pos = 'x';
    }

exit:
    return res;
}

static void
connection_dealloc(PyObject* obj)
{
    connectionObject *self = (connectionObject *)obj;

    if (self->weakreflist) {
        PyObject_ClearWeakRefs(obj);
    }

    PyObject_GC_UnTrack(self);

    if (self->closed == 0) conn_close(self);

    conn_notice_clean(self);

    if (self->dsn) free(self->dsn);
    PyMem_Free(self->encoding);
    PyMem_Free(self->codec);
    if (self->critical) free(self->critical);

    Py_CLEAR(self->tpc_xid);
    Py_CLEAR(self->async_cursor);
    Py_CLEAR(self->notice_list);
    Py_CLEAR(self->notice_filter);
    Py_CLEAR(self->notifies);
    Py_CLEAR(self->string_types);
    Py_CLEAR(self->binary_types);

    pthread_mutex_destroy(&(self->lock));

    Dprintf("connection_dealloc: deleted connection object at %p, refcnt = "
        FORMAT_CODE_PY_SSIZE_T,
        obj, Py_REFCNT(obj)
      );

    Py_TYPE(obj)->tp_free(obj);
}

static int
connection_init(PyObject *obj, PyObject *args, PyObject *kwds)
{
    const char *dsn;
    long int async = 0;
    static char *kwlist[] = {"dsn", "async", NULL};

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "s|l", kwlist, &dsn, &async))
        return -1;

    return connection_setup((connectionObject *)obj, dsn, async);
}

static PyObject *
connection_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    return type->tp_alloc(type, 0);
}

static void
connection_del(PyObject* self)
{
    PyObject_GC_Del(self);
}

static PyObject *
connection_repr(connectionObject *self)
{
    return PyString_FromFormat(
        "<connection object at %p; dsn: '%s', closed: %ld>",
        self, self->dsn, self->closed);
}

static int
connection_traverse(connectionObject *self, visitproc visit, void *arg)
{
    Py_VISIT((PyObject *)(self->tpc_xid));
    Py_VISIT(self->async_cursor);
    Py_VISIT(self->notice_list);
    Py_VISIT(self->notice_filter);
    Py_VISIT(self->notifies);
    Py_VISIT(self->string_types);
    Py_VISIT(self->binary_types);
    return 0;
}


/* object type */

#define connectionType_doc \
"connection(dsn, ...) -> new connection object\n\n" \
":Groups:\n" \
"  * `DBAPI-2.0 errors`: Error, Warning, InterfaceError,\n" \
"    DatabaseError, InternalError, OperationalError,\n" \
"    ProgrammingError, IntegrityError, DataError, NotSupportedError"

PyTypeObject connectionType = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "psycopg2._psycopg.connection",
    sizeof(connectionObject),
    0,
    connection_dealloc, /*tp_dealloc*/
    0,          /*tp_print*/
    0,          /*tp_getattr*/
    0,          /*tp_setattr*/
    0,          /*tp_compare*/
    (reprfunc)connection_repr, /*tp_repr*/
    0,          /*tp_as_number*/
    0,          /*tp_as_sequence*/
    0,          /*tp_as_mapping*/
    0,          /*tp_hash */

    0,          /*tp_call*/
    (reprfunc)connection_repr, /*tp_str*/
    0,          /*tp_getattro*/
    0,          /*tp_setattro*/
    0,          /*tp_as_buffer*/

    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
        Py_TPFLAGS_HAVE_WEAKREFS,
                /*tp_flags*/
    connectionType_doc, /*tp_doc*/

    (traverseproc)connection_traverse, /*tp_traverse*/
    0,          /*tp_clear*/

    0,          /*tp_richcompare*/
    offsetof(connectionObject, weakreflist), /* tp_weaklistoffset */

    0,          /*tp_iter*/
    0,          /*tp_iternext*/

    /* Attribute descriptor and subclassing stuff */

    connectionObject_methods, /*tp_methods*/
    connectionObject_members, /*tp_members*/
    connectionObject_getsets, /*tp_getset*/
    0,          /*tp_base*/
    0,          /*tp_dict*/

    0,          /*tp_descr_get*/
    0,          /*tp_descr_set*/
    0,          /*tp_dictoffset*/

    connection_init, /*tp_init*/
    0, /*tp_alloc  will be set to PyType_GenericAlloc in module init*/
    connection_new, /*tp_new*/
    (freefunc)connection_del, /*tp_free  Low-level free-memory routine */
    0,          /*tp_is_gc For PyObject_IS_GC */
    0,          /*tp_bases*/
    0,          /*tp_mro method resolution order */
    0,          /*tp_cache*/
    0,          /*tp_subclasses*/
    0           /*tp_weaklist*/
};
