/*
This file is part of TALER
Copyright (C) 2014-2017 Taler Systems SA
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, see
*/
/**
* @file taler-exchange-httpd_db.c
* @brief Generic database operations for the exchange.
* @author Christian Grothoff
*/
#include "platform.h"
#include
#include
#include
#include "taler_json_lib.h"
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_responses.h"
/**
* How often should we retry a transaction before giving up
* (for transactions resulting in serialization/dead locks only).
*
* The current value is likely too high for production. We might want to
* benchmark good values once we have a good database setup. The code is
* expected to work correctly with any positive value, albeit inefficiently if
* we too aggressively force clients to retry the HTTP request merely because
* we have database serialization issues.
*/
#define MAX_TRANSACTION_COMMIT_RETRIES 100
/**
* Ensure coin is known in the database, and handle conflicts and errors.
*
* @param coin the coin to make known
* @param connection MHD request context
* @param session database session and transaction to use
* @param[out] mhd_ret set to MHD status on error
* @return transaction status, negative on error (@a mhd_ret will be set in this case)
*/
enum GNUNET_DB_QueryStatus
TEH_make_coin_known (const struct TALER_CoinPublicInfo *coin,
struct MHD_Connection *connection,
struct TALER_EXCHANGEDB_Session *session,
MHD_RESULT *mhd_ret)
{
enum TALER_EXCHANGEDB_CoinKnownStatus cks;
/* make sure coin is 'known' in database */
cks = TEH_plugin->ensure_coin_known (TEH_plugin->cls,
session,
coin);
switch (cks)
{
case TALER_EXCHANGEDB_CKS_ADDED:
return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
case TALER_EXCHANGEDB_CKS_PRESENT:
return GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
case TALER_EXCHANGEDB_CKS_SOFT_FAIL:
return GNUNET_DB_STATUS_SOFT_ERROR;
case TALER_EXCHANGEDB_CKS_HARD_FAIL:
*mhd_ret
= TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_STORE_FAILED,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
case TALER_EXCHANGEDB_CKS_CONFLICT:
break;
}
{
struct TALER_EXCHANGEDB_TransactionList *tl;
enum GNUNET_DB_QueryStatus qs;
qs = TEH_plugin->get_coin_transactions (TEH_plugin->cls,
session,
&coin->coin_pub,
GNUNET_NO,
&tl);
if (0 > qs)
{
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mhd_ret = TALER_MHD_reply_with_error (
connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_FETCH_FAILED,
NULL);
return qs;
}
*mhd_ret
= TEH_RESPONSE_reply_coin_insufficient_funds (
connection,
TALER_EC_EXCHANGE_GENERIC_COIN_CONFLICTING_DENOMINATION_KEY,
&coin->coin_pub,
tl);
TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
tl);
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
/**
* Run a database transaction for @a connection.
* Starts a transaction and calls @a cb. Upon success,
* attempts to commit the transaction. Upon soft failures,
* retries @a cb a few times. Upon hard or persistent soft
* errors, generates an error message for @a connection.
*
* @param connection MHD connection to run @a cb for, can be NULL
* @param name name of the transaction (for debugging)
* @param[out] mhd_ret set to MHD response code, if transaction failed;
* NULL if we are not running with a @a connection and thus
* must not queue MHD replies
* @param cb callback implementing transaction logic
* @param cb_cls closure for @a cb, must be read-only!
* @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
*/
enum GNUNET_GenericReturnValue
TEH_DB_run_transaction (struct MHD_Connection *connection,
const char *name,
MHD_RESULT *mhd_ret,
TEH_DB_TransactionCallback cb,
void *cb_cls)
{
struct TALER_EXCHANGEDB_Session *session;
if (NULL != mhd_ret)
*mhd_ret = -1; /* set to invalid value, to help detect bugs */
if (NULL == (session = TEH_plugin->get_session (TEH_plugin->cls)))
{
GNUNET_break (0);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_SETUP_FAILED,
NULL);
return GNUNET_SYSERR;
}
for (unsigned int retries = 0;
retries < MAX_TRANSACTION_COMMIT_RETRIES;
retries++)
{
enum GNUNET_DB_QueryStatus qs;
if (GNUNET_OK !=
TEH_plugin->start (TEH_plugin->cls,
session,
name))
{
GNUNET_break (0);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_START_FAILED,
NULL);
return GNUNET_SYSERR;
}
qs = cb (cb_cls,
connection,
session,
mhd_ret);
if (0 > qs)
TEH_plugin->rollback (TEH_plugin->cls,
session);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
return GNUNET_SYSERR;
if (0 <= qs)
qs = TEH_plugin->commit (TEH_plugin->cls,
session);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
{
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_COMMIT_FAILED,
NULL);
return GNUNET_SYSERR;
}
/* make sure callback did not violate invariants! */
GNUNET_assert ( (NULL == mhd_ret) ||
(-1 == *mhd_ret) );
if (0 <= qs)
return GNUNET_OK;
}
TALER_LOG_ERROR ("Transaction `%s' commit failed %u times\n",
name,
MAX_TRANSACTION_COMMIT_RETRIES);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_SOFT_FAILURE,
NULL);
return GNUNET_SYSERR;
}
/* end of taler-exchange-httpd_db.c */